JP2020138139A - Photocatalytic material and method for manufacturing the same - Google Patents
Photocatalytic material and method for manufacturing the same Download PDFInfo
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- JP2020138139A JP2020138139A JP2019035519A JP2019035519A JP2020138139A JP 2020138139 A JP2020138139 A JP 2020138139A JP 2019035519 A JP2019035519 A JP 2019035519A JP 2019035519 A JP2019035519 A JP 2019035519A JP 2020138139 A JP2020138139 A JP 2020138139A
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Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
Landscapes
- Oxygen, Ozone, And Oxides In General (AREA)
- Catalysts (AREA)
Abstract
Description
本発明は、水の光分解反応を触媒する光触媒粒子を含む光触媒層が基板に固定化されてなる光触媒材及びその製造方法に関する。 The present invention relates to a photocatalytic material in which a photocatalytic layer containing photocatalytic particles for catalyzing a photocatalytic reaction of water is immobilized on a substrate, and a method for producing the same.
光応答型光触媒は光を利用可能な光触媒である。光応答型光触媒の中でも、太陽光に多く含まれる可視光線を利用可能な光触媒である可視光応答型光触媒が広く利用されている。この可視光応答型光触媒は、有機物の光分解や、水の光分解による水素製造への応用に期待されている。中でも、水素の製造を目的とした水分解用光触媒は、再生可能エネルギーを利用した水素製造方法に用いられる光触媒として注目されている。その結果、高い活性が得られる水分解用光触媒への要求が年々高まっている。 A photocatalyst is a photocatalyst that can use light. Among the photocatalysts, the visible light responsive photocatalyst, which is a photocatalyst capable of utilizing visible light contained in a large amount of sunlight, is widely used. This visible light responsive photocatalyst is expected to be applied to photodecomposition of organic substances and hydrogen production by photodecomposition of water. Among them, a photocatalyst for water decomposition for the purpose of producing hydrogen is attracting attention as a photocatalyst used in a hydrogen production method using renewable energy. As a result, the demand for photocatalysts for water splitting, which can obtain high activity, is increasing year by year.
光触媒を用いた水分解による水素製造技術として、光触媒粒子を基板に固定化した膜（光触媒層）の開発が進められてきている。例えば、特開２０１２−１８７５２０号公報（特許文献１）には、基材上に光触媒層を有する水分解用光触媒固定化物であって、光触媒層が窒化物又は酸窒化物である可視光応答型光半導体と、可視光応答型光半導体に担持された助触媒と、親水性無機材料とを含む、光触媒固定化物が例示されている。特許文献１によれば、親水性無機材料粒子を共存させることによって、光触媒層内に水が浸入し易くなり、光触媒層の内部においても光水分解反応を生じさせることができ、また、親水性表面によって生成ガスが光触媒層に付着し難くなる結果、生成ガスの気相中への拡散が促進されるため、反応効率が向上したとされている。 As a hydrogen production technique by water splitting using a photocatalyst, the development of a film (photocatalyst layer) in which photocatalyst particles are immobilized on a substrate has been promoted. For example, Japanese Patent Application Laid-Open No. 2012-187520 (Patent Document 1) describes a photocatalyst-immobilized product for water splitting having a photocatalyst layer on a substrate, and is a visible light responsive type in which the photocatalyst layer is a nitride or an acid nitride. A photocatalyst immobilized product containing a photosemiconductor, a cocatalyst supported on a visible light responsive photosemiconductor, and a hydrophilic inorganic material is exemplified. According to Patent Document 1, the coexistence of hydrophilic inorganic material particles facilitates the infiltration of water into the photocatalyst layer, can cause a photowater decomposition reaction inside the photocatalyst layer, and is hydrophilic. It is said that the surface makes it difficult for the produced gas to adhere to the photocatalyst layer, and as a result, the diffusion of the produced gas into the gas phase is promoted, so that the reaction efficiency is improved.
ＷＯ２０１４／０４６３０５号公報（特許文献２）には、基材と、基材に固定化されてなる光触媒層とを含んでなる光触媒材であって、光触媒層が、一次粒子径が１００ｎｍ以下である水素発生用可視光応答型光触媒粒子と、酸素発生用可視光応答型光触媒粒子とを含むものが例示されている。この例では、水素発生用可視光応答型光触媒粒子と酸素発生用可視光応答型光触媒粒子とが互いに接触している。 According to WO2014 / 046305 (Patent Document 2), a photocatalyst material including a base material and a photocatalyst layer immobilized on the base material, wherein the photocatalyst layer has a primary particle size of 100 nm or less. Examples include those containing visible light responsive photocatalyst particles for hydrogen generation and visible light responsive photocatalyst particles for oxygen generation. In this example, the visible light responsive photocatalyst particles for hydrogen generation and the visible light responsive photocatalyst particles for oxygen evolution are in contact with each other.
特開２０１７−１２４３９３号公報（特許文献３）には、基材と、基材に固定化されてなる光触媒層とを含んでなる光触媒材であって、光触媒層が、水素発生用可視光応答型の第１の光触媒粒子と、酸素発生用可視光応答型の第２の光触媒粒子と、特定のエネルギー準位を有する導電性粒子とを含むものが例示されている。この例では、光触媒層において、導電性粒子が第１の光触媒粒子と第２の光触媒粒子とに接続されるように配置され、導電性粒子により電気性に接続された第１の光触媒粒子および第２の光触媒粒子は高い光触媒活性を発現することが可能とされている。 Japanese Patent Application Laid-Open No. 2017-124393 (Patent Document 3) describes a photocatalyst material including a base material and a photocatalyst layer immobilized on the base material, wherein the photocatalyst layer is a visible light response for hydrogen generation. Examples include a first photocatalytic particle of the type, a second photocatalytic particle of the visible light responsive type for generating oxygen, and conductive particles having a specific energy level. In this example, in the photocatalyst layer, the first photocatalyst particles and the first photocatalyst particles are arranged so that the conductive particles are connected to the first photocatalyst particles and the second photocatalyst particles, and are electrically connected by the conductive particles. The photocatalytic particles of No. 2 are capable of exhibiting high photocatalytic activity.
特開２０１７−１５５３３２号公報（特許文献４）には、基板である第１導電体と、第１導電体上に配置された複数のピラー構造体を含み、かつ透明である第２導電体と、ピラー構造体の表面上に配置された、可視光光触媒を含む光触媒層とを含む光電極が例示されている。この例では、光電極を水分解の電極として利用する場合、光電極の光触媒層側の面がピラー構造体の形状を反映した凹凸形状を有することにより、水分解反応によって発生した気泡（水素又は酸素）が光電極外へ放出しやすいため、水分解反応の効率を高めることが可能とされている。しかしながら、この例では、光触媒層を担持するピラー構造体の凹凸形状を光触媒層に反映することにより、光電極構造中にマクロ的に凹凸形状の光触媒層を形成しているに過ぎない。つまり、この例では、光触媒層自体が凹凸形状を有しているわけではなく、また光触媒層の膜厚は一定である。 Japanese Unexamined Patent Publication No. 2017-155332 (Patent Document 4) includes a first conductor which is a substrate, and a second conductor which includes a plurality of pillar structures arranged on the first conductor and is transparent. , A photoelectrode including a photocatalyst layer containing a visible photocatalyst arranged on the surface of the pillar structure is exemplified. In this example, when the photoelectrode is used as an electrode for water splitting, the surface of the photoelectrode on the photocatalyst layer side has an uneven shape that reflects the shape of the pillar structure, so that bubbles (hydrogen or hydrogen or bubbles generated by the water splitting reaction) are generated. Since oxygen) is easily released to the outside of the photoelectrode, it is possible to improve the efficiency of the water splitting reaction. However, in this example, the concave-convex shape of the pillar structure supporting the photocatalyst layer is reflected in the photocatalyst layer, so that the photocatalyst layer having a macroscopically concave-convex shape is simply formed in the photocatalyst structure. That is, in this example, the photocatalyst layer itself does not have an uneven shape, and the film thickness of the photocatalyst layer is constant.
上で述べた従来技術において、特許文献４に記載された光電極は、凹凸形状を有する導電体の上に、一定の厚さで光触媒層を形成し、光触媒層の形状を間接的に凹凸形状としたものである。特許文献４では、光触媒層の構造（形状）を工夫することで、光触媒層の光触媒活性、つまり水素発生能の向上が試みられている。しかし、特許文献４の光電極は、対電極と電気的に接続されてリアクタを構成するものである。つまり、特許文献４の光電極は、水素または酸素のいずれかを生成するため、別途水素または酸素を生成可能な対極を必要とする点で、構造が複雑になる。引用文献４にあっては、水素および酸素双方を同一の表面で同時に生成することはそもそも考慮されておらず、また不可能である。 In the prior art described above, the photoelectrode described in Patent Document 4 forms a photocatalyst layer with a certain thickness on a conductor having an uneven shape, and indirectly changes the shape of the photocatalyst layer into an uneven shape. It is the one. In Patent Document 4, an attempt is made to improve the photocatalytic activity of the photocatalytic layer, that is, the hydrogen generating ability, by devising the structure (shape) of the photocatalytic layer. However, the photoelectrode of Patent Document 4 is electrically connected to the counter electrode to form a reactor. That is, since the photoelectrode of Patent Document 4 generates either hydrogen or oxygen, the structure is complicated in that a counter electrode capable of separately generating hydrogen or oxygen is required. In Cited Document 4, it is not considered or impossible to simultaneously generate both hydrogen and oxygen on the same surface.
一方、特許文献１〜３に記載された光触媒材は、基材に固定化された光触媒層の同一表面で水素と酸素とを同時に生成する光触媒システムである。これら特許文献では、光触媒層を構成する光触媒粒子の種類や物性（大きさ、電気化学的特性など）、光触媒粒子とともに光触媒層を形成する他の材料を工夫し、あるいは光触媒層における構成材料の配置を工夫することで、光触媒層の光触媒活性の向上が試みられている。 On the other hand, the photocatalyst materials described in Patent Documents 1 to 3 are photocatalyst systems that simultaneously generate hydrogen and oxygen on the same surface of a photocatalyst layer immobilized on a substrate. In these patent documents, the types and physical properties (size, electrochemical characteristics, etc.) of the photocatalyst particles constituting the photocatalyst layer, other materials forming the photocatalyst layer together with the photocatalyst particles are devised, or the constituent materials are arranged in the photocatalyst layer. Attempts have been made to improve the photocatalytic activity of the photocatalytic layer by devising.
しかし、光触媒層の同一表面で水素と酸素とを同時に生成する光触媒システムにおいては、光触媒が水の分解反応の活性化エネルギーを低下させるため、一旦発生した水素と酸素とが光触媒に接触することによって水が再生成される、いわゆる逆反応も起こりやすくなるという課題がある。この課題を解決するために、特許文献１では、基材上に製膜された水分解用光触媒層に親水性無機材料を含有させて生成ガスの拡散を促進させる技術が開示されているが、本発明者らの行った実験によれば、特許文献１に記載された技術では、水分解性能が期待通りに向上しないことが判明しており、その理由の一つとして、生成した水素ガスおよび／または酸素ガスが光触媒層の表面に滞留しやすいことが考えられる。 However, in a photocatalyst system that simultaneously produces hydrogen and oxygen on the same surface of the photocatalyst layer, the photocatalyst reduces the activation energy of the decomposition reaction of water, so that once generated hydrogen and oxygen come into contact with the photocatalyst. There is a problem that water is regenerated, that is, a so-called reverse reaction is likely to occur. In order to solve this problem, Patent Document 1 discloses a technique in which a hydrophilic inorganic material is contained in a photocatalyst layer for water splitting formed on a base material to promote diffusion of produced gas. According to the experiments conducted by the present inventors, it has been found that the water decomposition performance is not improved as expected by the technique described in Patent Document 1, and one of the reasons is the generated hydrogen gas and / Or it is considered that oxygen gas tends to stay on the surface of the photocatalyst layer.
本発明者らは、今般、光照射下で水を分解して水素および酸素を光触媒層の同一表面で同時に生成する光触媒材において、当該光触媒層自体のミクロ的な表面形状に着眼し、その表面形状を特定の凹凸形状とすることにより、水分解反応によって発生する水素又は酸素ガスを当該特定の凹凸形状の表面から効率的に採取することができるとともに、一旦発生した水素と酸素とが光触媒に接触することによって水が再生成される、いわゆる逆反応を抑制することができ、その結果、水を高効率に光分解することが可能となり、水素発生能を向上させることが可能となることを見出した。本発明は斯かる知見に基づくものである。 The present inventors have recently focused on the microscopic surface shape of the photocatalyst layer itself in a photocatalyst material that decomposes water under light irradiation to simultaneously generate hydrogen and oxygen on the same surface of the photocatalyst layer, and the surface thereof. By making the shape a specific concavo-convex shape, hydrogen or oxygen gas generated by the water splitting reaction can be efficiently collected from the surface of the specific concavo-convex shape, and the once generated hydrogen and oxygen become a photocatalyst. It is possible to suppress the so-called reverse reaction in which water is regenerated by contact, and as a result, it is possible to photodecompose water with high efficiency and improve the hydrogen generation ability. I found it. The present invention is based on such findings.
従って、本発明は、光照射下で水を分解して水素および酸素を光触媒層の同一表面で同時に生成する光触媒材であって、水分解反応によって発生する水素又は酸素を、逆反応を抑制しながら効率的に採取することが可能であり、とりわけ水素発生能が高められた光触媒材の提供をその目的としている。 Therefore, the present invention is a photocatalytic material that decomposes water under light irradiation to simultaneously generate hydrogen and oxygen on the same surface of the photocatalytic layer, and suppresses the reverse reaction of hydrogen or oxygen generated by the water decomposition reaction. However, the purpose is to provide a photocatalytic material that can be efficiently collected and has an enhanced hydrogen generating ability.
そして、本発明による光触媒材は、
絶縁性の基板と、前記基板上に形成された光触媒層とを備えてなり、
前記光触媒層が、水の光分解反応を触媒する光触媒粒子と、親水性バインダーとを含んでなる多孔質な層であり、かつ、複数の凹部および凸部を含む凹凸形状を有してなり、
前記光触媒層において、前記凸部と前記凹部との高低差が５μｍ以上１００μｍ以下であり、かつ、前記凸部の厚さが前記凹部の厚さよりも大である
ことを特徴とするものである。
The photocatalytic material according to the present invention is
It comprises an insulating substrate and a photocatalyst layer formed on the substrate.
The photocatalyst layer is a porous layer containing photocatalyst particles for catalyzing the photocatalytic reaction of water and a hydrophilic binder, and has an uneven shape including a plurality of concave portions and convex portions.
The photocatalyst layer is characterized in that the height difference between the convex portion and the concave portion is 5 μm or more and 100 μm or less, and the thickness of the convex portion is larger than the thickness of the concave portion.
本発明による光触媒材によれば、水分解反応によって発生する水素又は酸素を、逆反応を抑制しながら効率的に採取することが可能であり、とりわけ水素発生能が高められた光触媒材を得ることができる。 According to the photocatalytic material according to the present invention, hydrogen or oxygen generated by the water splitting reaction can be efficiently collected while suppressing the reverse reaction, and in particular, a photocatalytic material having an enhanced hydrogen generating ability can be obtained. Can be done.
定義
本明細書において、「光」とは、電磁波を意味する。「可視光」とは、人間の目で視認可能な波長の光を意味する。好ましくは、波長３８０ｎｍ以上の可視光線を含む光、より好ましくは、波長４２０ｎｍ以上の可視光線を含む光を意味する。また、可視光線を含む光としては、太陽光、集光してエネルギー密度を高めた集光太陽光、あるいはキセノンランプ、ハロゲンランプ、ナトリウムランプ、蛍光灯、発光ダイオード等の人工光源を光源として用いることが可能である。好ましくは、地球上に無尽蔵に降り注いでいる太陽光を光源として用いる。これにより、太陽光線の約６０％を占める紫外線（波長４２０ｎｍ以下）および可視光線（波長４２０〜７８０ｎｍ）を利用可能であり、水から水素及び酸素を効率的に取り出すことが可能となる。可視光線より波長の短いものを「紫外線」、長いものを「赤外線」という。
Definitions As used herein, "light" means electromagnetic waves. "Visible light" means light of a wavelength visible to the human eye. It preferably means light containing visible light having a wavelength of 380 nm or more, and more preferably light containing visible light having a wavelength of 420 nm or more. As the light including visible light, sunlight, condensed sunlight whose energy density is increased by condensing it, or an artificial light source such as a xenon lamp, a halogen lamp, a sodium lamp, a fluorescent lamp, or a light emitting diode is used as a light source. It is possible. Preferably, the inexhaustible amount of sunlight falling on the earth is used as a light source. As a result, ultraviolet rays (wavelength 420 nm or less) and visible light (wavelength 420 to 780 nm) that occupy about 60% of the sunlight can be used, and hydrogen and oxygen can be efficiently extracted from water. Those with shorter wavelengths than visible light are called "ultraviolet rays", and those with longer wavelengths are called "infrared rays".
本明細書において、「水素発生用可視光応答型光触媒粒子」とは、可視光による水の光分解反応により水素を発生可能な光触媒粒子を意味し、「酸素発生用可視光応答型光触媒粒子」とは、可視光による水の光分解反応により酸素を発生可能な光触媒粒子を意味する。 In the present specification, the "visible light responsive photocatalytic particle for hydrogen generation" means a photocatalyst particle capable of generating hydrogen by a photocatalytic reaction of water with visible light, and is "visible light responsive photocatalytic particle for oxygen generation". Means photocatalytic particles capable of generating oxygen by the photocatalytic reaction of water with visible light.
光触媒材
本発明による光触媒材の全体構成について図１を参照しつつ説明する。光触媒材１００は、絶縁性の基板２と、絶縁性の基板２に固定化されてなる光触媒層１とを含む。光触媒層１は、複数の凹部１２および凸部１１を含む凹凸形状を表面に有する。光触媒層１は、後記のとおり、凸部１１と凹部１２との高低差Ｄ１が所定範囲にあり、かつ、凸部１１の厚さＴ１１の平均値が凹部１２の厚さＴ１２の平均値よりも大であるとの特徴を有する。
With reference to Figure 1 the overall construction of a photocatalytic material by the photocatalyst material present invention will be described. The photocatalyst material 100 includes an insulating substrate 2 and a photocatalyst layer 1 immobilized on the insulating substrate 2. The photocatalyst layer 1 has an uneven shape on the surface including a plurality of concave portions 12 and convex portions 11. As described later, the photocatalyst layer 1 has a height difference D 1 between the convex portion 11 and the concave portion 12 within a predetermined range, and the average value of the thickness T 11 of the convex portion 11 is the average of the thickness T 12 of the concave portion 12. It has the characteristic that it is larger than the value.
本発明による光触媒材は、絶縁性の基板２上に光触媒層１が形成され、光触媒層１の同一表面で水を直接水素と酸素に分解できるため、複雑なシステムを必要とせずに、水素および／または酸素を取り出すことが可能となる。 In the photocatalyst material according to the present invention, since the photocatalyst layer 1 is formed on the insulating substrate 2 and water can be directly decomposed into hydrogen and oxygen on the same surface of the photocatalyst layer 1, hydrogen and hydrogen and oxygen can be decomposed without requiring a complicated system. / Or oxygen can be taken out.
本発明による光触媒材は、光触媒層１の表面が少なくとも上述したような特定の凹凸形状を有するものとしたことにより、水を高効率に光分解可能であり、その結果、水素発生能を向上させることができる。その理由は定かではないが、以下のように予想される。ただし、以下の説明はあくまで仮定であって、本発明がその理論に拘束されることを意図するものではない。光触媒層１の表面が上述したような特定の凹凸形状を有することで、光触媒材が水と接した際、光触媒層の表面における水素ガス及び／又は酸素ガスの気泡の成長を、凹凸形状の傾斜面または垂直面により、抑制することができるものと考えられる。つまり、気泡が成長する前に、水素ガス及び／又は酸素ガスは、光触媒層の表面から速やかに離脱する。より具体的には、凸部表面で生成した水素及び／又は酸素ガスは、その傾斜表面で気泡が成長する際、気泡が上下対称な形状を取ることができず、表面での継続的な成長が難しくなることで、浮力により速やかに離脱することが可能となる。さらに、光触媒層の形状を、凸部の厚さを凹部の厚さよりも大とすることで、光触媒層の表面全体からバラツキなく水素および酸素を効率的に生成することが可能となる。例えば、凹凸表面を有する基板上に、均一な厚さで光触媒層を製膜して、基板の凹凸形状を反映した表面形状を有する光触媒層を形成する場合、凹凸を形成可能な基板の材質が限定されるといった懸念がある。あるいは、凹凸表面を有する基板は、表面への異物付着等により濡れ性が不均一になりやすくなり、形成される光触媒層において、被覆が不十分な部分（被覆不良部）が生じる懸念がある。このような場合、光触媒層の凸部において被覆不良部が発生する傾向が高く、その結果、基板全面に対する光触媒の被覆率が低下する。これに対して、本発明にあっては、光触媒層を、凸部の厚さを凹部の厚さよりも大きい形状とすることで、好適には、光触媒層の凸部の厚さを凹部の厚さよりも大とする形状を、基板の凹凸によらず、凸部と凹部を光触媒のみで形成することで、光触媒層における被覆不良部の発生を低減することが可能となり、結果的に水素および酸素の効率的な生成が可能となる。また、光触媒層を凸部の厚さが凹部の厚さよりも大きい形状とすることで、凹部よりも凸部でのガス生成が促進される。これにより、水素ガス及び／又は酸素ガスは効率的に系外に放出されるため、水分解により一旦発生した水素および酸素が反応して水を生成する逆反応を有効に防止することが可能となる。 In the photocatalyst material according to the present invention, since the surface of the photocatalyst layer 1 has at least a specific uneven shape as described above, water can be photodecomposed with high efficiency, and as a result, the hydrogen generation ability is improved. be able to. The reason is not clear, but it is expected as follows. However, the following description is only a hypothesis and is not intended to be bound by the theory of the present invention. By having the surface of the photocatalyst layer 1 having a specific uneven shape as described above, when the photocatalyst material comes into contact with water, the growth of bubbles of hydrogen gas and / or oxygen gas on the surface of the photocatalyst layer is prevented by the inclination of the uneven shape. It is considered that it can be suppressed by a plane or a vertical plane. That is, the hydrogen gas and / or the oxygen gas rapidly separate from the surface of the photocatalyst layer before the bubbles grow. More specifically, hydrogen and / or oxygen gas generated on the surface of the convex portion cannot take a vertically symmetrical shape when bubbles grow on the inclined surface, and continuously grow on the surface. By making it difficult, it becomes possible to quickly separate due to buoyancy. Further, by making the shape of the photocatalyst layer larger than the thickness of the concave portion, it is possible to efficiently generate hydrogen and oxygen from the entire surface of the photocatalyst layer without variation. For example, when a photocatalyst layer having a uniform thickness is formed on a substrate having an uneven surface to form a photocatalyst layer having a surface shape reflecting the uneven shape of the substrate, the material of the substrate capable of forming the unevenness is There is a concern that it will be limited. Alternatively, a substrate having an uneven surface tends to have non-uniform wettability due to foreign matter adhering to the surface, and there is a concern that an insufficiently coated portion (poor coating portion) may occur in the formed photocatalyst layer. In such a case, a poorly coated portion tends to occur in the convex portion of the photocatalyst layer, and as a result, the coverage ratio of the photocatalyst on the entire surface of the substrate decreases. On the other hand, in the present invention, the photocatalyst layer has a shape in which the thickness of the convex portion is larger than the thickness of the concave portion, so that the thickness of the convex portion of the photocatalyst layer is preferably the thickness of the concave portion. By forming the convex and concave portions only with the photocatalyst, regardless of the unevenness of the substrate, it is possible to reduce the occurrence of poorly coated portions in the photocatalyst layer, resulting in hydrogen and oxygen. Can be efficiently generated. Further, by forming the photocatalyst layer into a shape in which the thickness of the convex portion is larger than the thickness of the concave portion, gas generation in the convex portion is promoted rather than in the concave portion. As a result, hydrogen gas and / or oxygen gas is efficiently released to the outside of the system, so that it is possible to effectively prevent the reverse reaction in which hydrogen and oxygen once generated by water decomposition react to generate water. Become.
したがって、本発明による光触媒材は、光触媒層の表面が平滑である場合に比べて、光照射下で高い光触媒活性を発現することができ、高い効率で水を光分解することが可能となり、高い水素発生能を有する。換言すると、本発明による光触媒材は、光触媒層の表面に特定の凹凸形状が付与されているため、光触媒層の表面が平滑である場合に比べて、形状の相違のみにより、すなわち光触媒層を構成する光触媒粒子の種類や物性、光触媒粒子とともに光触媒層を形成する他の材料、光触媒層におけるこれら構成材料の配置、基材の材質や形状、あるいは照射光源波長などの諸条件を問わず、水素発生効率を向上させることが可能となる。 Therefore, the photocatalytic material according to the present invention can exhibit high photocatalytic activity under light irradiation as compared with the case where the surface of the photocatalytic layer is smooth, and can photodecompose water with high efficiency, which is high. Has the ability to generate hydrogen. In other words, since the photocatalyst material according to the present invention is provided with a specific uneven shape on the surface of the photocatalyst layer, the photocatalyst layer is formed only by the difference in shape as compared with the case where the surface of the photocatalyst layer is smooth. Hydrogen generation regardless of various conditions such as the type and physical properties of the photocatalyst particles, other materials that form the photocatalyst layer together with the photocatalyst particles, the arrangement of these constituent materials in the photocatalyst layer, the material and shape of the base material, or the wavelength of the irradiation light source. It is possible to improve efficiency.
光触媒層
凹凸形状
光触媒層１は、例えば図１に示すように、複数の凹部１２および凸部１１を含む凹凸形状を有する。本明細書において、「凹凸形状」とは、光触媒層の表面が平滑ではない形状を有することを意味する。例えば、凹凸形状の他、山型、波型、くし型およびピラー型などの非平滑表面形状を広く含む。凹凸形状は、規則的であってもよく、不規則であってもよい。なお、光触媒層の表面形状が、本明細書に記載の特定の凹凸形状、とりわけ後記の形状的特徴を有する凹凸形状である限りにおいて、基板の形状の影響の有無は問わない。すなわち、本発明は、基板の形状の影響を受けずに（例えば、表面が平滑な基板）、当該基板の上に特定の凹凸形状を有する光触媒層が形成されている態様を含む。
Photocatalytic layer
Concavo-convex shape The photocatalyst layer 1 has a concavo-convex shape including a plurality of concave portions 12 and convex portions 11, as shown in FIG. 1, for example. As used herein, the term "concavo-convex shape" means that the surface of the photocatalyst layer has a non-smooth shape. For example, in addition to the uneven shape, a wide range of non-smooth surface shapes such as chevron, wavy, comb and pillar shapes are included. The uneven shape may be regular or irregular. As long as the surface shape of the photocatalyst layer is a specific uneven shape described in the present specification, particularly an uneven shape having the shape characteristics described later, it does not matter whether or not the shape of the substrate has an effect. That is, the present invention includes an embodiment in which a photocatalyst layer having a specific uneven shape is formed on the substrate without being affected by the shape of the substrate (for example, a substrate having a smooth surface).
凸部と凹部との高低差
光触媒層１において、凸部１１と凹部１２との高低差Ｄ１は、５μｍ以上１００μｍ以下である。この形状的特徴により、光触媒層の表面における水素ガス及び／又は酸素ガスの気泡の成長を抑制し、水素ガス及び／又は酸素ガスを光触媒層の表面から速やかに離脱させることが可能となるとともに、水分解により一旦発生した水素および酸素が反応して再び水を生成する逆反応を防止することが可能となる。凸部１１と凹部１２との高低差Ｄ１は、５μｍ以上８０μｍ以下であることが好ましい。
Height difference between the convex portion and the concave portion In the photocatalyst layer 1, the height difference D 1 between the convex portion 11 and the concave portion 12 is 5 μm or more and 100 μm or less. Due to this shape feature, it is possible to suppress the growth of bubbles of hydrogen gas and / or oxygen gas on the surface of the photocatalyst layer, and to allow hydrogen gas and / or oxygen gas to be rapidly separated from the surface of the photocatalyst layer. It is possible to prevent the reverse reaction in which hydrogen and oxygen once generated by water decomposition react to generate water again. The height difference D 1 between the convex portion 11 and the concave portion 12 is preferably 5 μm or more and 80 μm or less.
本発明において、光触媒層における凸部と凹部との高低差Ｄ１は、例えば以下のように測定される。
レーザー顕微鏡に所定倍率の光学レンズを装着し、所定の視野にて光触媒層を観察し、光触媒層表面の三次元画像を得る。得られた画像において、任意に選択した５点の凸部の各頂点又は頂上部１１Ｓ（以下、「山頂点又は山頂部」ということもある）までの高さ（Ｈ１１Ｓ）を測定し、それらの平均値（Ｈ１１Ｓ０）を求める。また、得られた画像において、任意に選択した５点の凹部の各底点又は底部１２Ｂ（以下、「谷底点又は谷底部」ということもある）までの高さ（Ｈ１２Ｂ）を測定し、それらの平均値（Ｈ１２Ｂ０）を求める。Ｈ１１Ｓ０−Ｈ１２Ｂ０により、所定角の視野での光触媒層における凸部と凹部との高低差を求める。
上記の視野とは異なる視野でさらに幾つかの観察を行い、各視野での光触媒層における凸部と凹部との高低差を求める。異なる視野での光触媒層における凸部と凹部との高低差の平均値を、光触媒層における凸部と凹部との高低差とする。
In the present invention, the height difference D 1 between the convex portion and the concave portion in the photocatalyst layer is measured as follows, for example.
An optical lens having a predetermined magnification is attached to a laser microscope, the photocatalyst layer is observed in a predetermined field of view, and a three-dimensional image of the surface of the photocatalyst layer is obtained. In the obtained image, the height (H 11S ) to each apex or the summit 11S (hereinafter, also referred to as “mountain apex or summit”) of the five arbitrarily selected convex portions is measured, and they are measured. The average value of (H 11S0 ) is calculated . Further, in the obtained image, the height (H 12B ) to each bottom point or bottom 12B (hereinafter, also referred to as “valley bottom point or valley bottom”) of the five arbitrarily selected recesses is measured. The average value (H 12B0 ) of them is calculated. From H 11S0 to H 12B0 , the height difference between the convex portion and the concave portion in the photocatalyst layer in the visual field at a predetermined angle is obtained.
Some further observations are made in a field of view different from the above field of view, and the height difference between the convex portion and the concave portion in the photocatalyst layer in each visual field is obtained. The average value of the height difference between the convex portion and the concave portion in the photocatalyst layer in different fields of view is defined as the height difference between the convex portion and the concave portion in the photocatalyst layer.
凸部の厚さと凹部の厚さとの関係
光触媒層１において、凸部１１の厚さ（Ｔ１１）は凹部１２の厚さ（Ｔ１２）よりも大である。この形状的特徴により、光触媒層の表面における水素ガス及び／又は酸素ガスの気泡の成長を抑制し、水素ガス及び／又は酸素ガスを光触媒層の表面から速やかに離脱させることが可能となるとともに、水分解により一旦発生した水素および酸素が反応して再び水を生成する逆反応を防止することが可能となる。また、凸部の厚さが凹部の厚さよりも大である、すなわち凹部の厚さが凸部の厚さよりも小であることで、光の照射角度による凸部の影が凹部にできにくく、凹部にも光を効率的に照射することが可能となり、光触媒層の全面を有効に利用することが可能となる。さらに、凸部の厚さが凹部の厚さよりも大きいことで、基板の表面形状（例えば、凹凸）に左右されずに水分解反応を進行させることが可能となる。同時に、凸部の厚さが凹部の厚さよりも大きいことで、基材の凹凸に依存せずに水と光触媒との接触界面が大きくなるため、光触媒層内で生成する水素および酸素ガスが光触媒層の中から表面に拡散し易くなる。その結果、水素および酸素の逆反応を抑制することも可能となる。さらに、水素および酸素ガスが光触媒層の凹凸表面に拡散した際に生成する気泡の形状が、凹凸表面の斜面形状のため上下非対称となることで、気泡の成長が起こる前に浮力により、気泡の水中への離脱を促進することができる。さらに、光触媒層を凸部の厚さが凹部の厚さよりも大きい形状とすることで、光触媒層の表面全体からバラツキなく水素および酸素を効率的に生成することが可能となる。例えば、凹凸表面を有する基板上に、均一な厚さで光触媒層を製膜して、基板の凹凸形状を反映した表面形状を有する光触媒層を形成する場合、凹凸表面を有する基板は、表面への異物付着等により濡れ性が不均一になりやすく、形成される光触媒層において、被覆が不十分な部分（被覆不良部）が生じる懸念がある。このような場合、光触媒層の凸部において被覆不良部が発生する傾向が高く、その結果、基板全面に対する光触媒の被覆率が低下する。これに対して、本発明にあっては、光触媒層を、凸部の厚さが凹部の厚さよりも大きい形状とすることで、好適には、光触媒層の凸部の厚さを凹部の厚さよりも大とする形状を、基板の凹凸によらず、凸部と凹部を光触媒層のみで形成することで、光触媒層における被覆不良部の発生を低減させ、水素および酸素の効率的な生成が可能となるとともに、凹部よりも凸部でのガス生成が促進され、水素ガス及び／又は酸素ガスの効率的な系外への放出により、逆反応を有効に防止することが可能となる。
Relationship between the thickness of the convex portion and the thickness of the concave portion In the photocatalyst layer 1, the thickness of the convex portion 11 (T 11 ) is larger than the thickness of the concave portion 12 (T 12 ). Due to this shape feature, it is possible to suppress the growth of bubbles of hydrogen gas and / or oxygen gas on the surface of the photocatalyst layer, and to allow hydrogen gas and / or oxygen gas to be rapidly separated from the surface of the photocatalyst layer. It is possible to prevent the reverse reaction in which hydrogen and oxygen once generated by water decomposition react to generate water again. Further, since the thickness of the convex portion is larger than the thickness of the concave portion, that is, the thickness of the concave portion is smaller than the thickness of the convex portion, the shadow of the convex portion due to the irradiation angle of light is less likely to be formed on the concave portion. It is possible to efficiently irradiate the recesses with light, and it is possible to effectively use the entire surface of the photocatalyst layer. Further, since the thickness of the convex portion is larger than the thickness of the concave portion, the water splitting reaction can proceed regardless of the surface shape (for example, unevenness) of the substrate. At the same time, since the thickness of the convex portion is larger than the thickness of the concave portion, the contact interface between water and the photocatalyst becomes large regardless of the unevenness of the base material, so that the hydrogen and oxygen gas generated in the photocatalyst layer become the photocatalyst. It is easy to diffuse from the layer to the surface. As a result, it is possible to suppress the reverse reaction of hydrogen and oxygen. Furthermore, the shape of the bubbles generated when hydrogen and oxygen gas diffuses on the uneven surface of the photocatalyst layer becomes vertically asymmetric due to the slope shape of the uneven surface, and the buoyancy of the bubbles before the growth of the bubbles occurs. It can promote the withdrawal into the water. Further, by forming the photocatalyst layer into a shape in which the thickness of the convex portion is larger than the thickness of the concave portion, hydrogen and oxygen can be efficiently generated from the entire surface of the photocatalyst layer without variation. For example, when a photocatalyst layer having a uniform thickness is formed on a substrate having an uneven surface to form a photocatalyst layer having a surface shape reflecting the uneven shape of the substrate, the substrate having an uneven surface is transferred to the surface. Wetting properties tend to be non-uniform due to foreign matter adhering to the photocatalyst layer, and there is a concern that an insufficiently coated portion (poor coating portion) may occur in the formed photocatalyst layer. In such a case, a poorly coated portion tends to occur in the convex portion of the photocatalyst layer, and as a result, the coverage ratio of the photocatalyst on the entire surface of the substrate decreases. On the other hand, in the present invention, the photocatalyst layer has a shape in which the thickness of the convex portion is larger than the thickness of the concave portion, so that the thickness of the convex portion of the photocatalyst layer is preferably set to the thickness of the concave portion. By forming the convex and concave parts only with the photocatalyst layer, regardless of the unevenness of the substrate, the shape to be larger than that is reduced from the occurrence of poorly coated parts in the photocatalyst layer, and efficient generation of hydrogen and oxygen can be achieved. At the same time, gas generation is promoted at the convex portion rather than the concave portion, and the reverse reaction can be effectively prevented by the efficient release of hydrogen gas and / or oxygen gas to the outside of the system.
基板の表面を凹凸形状にして、この基材の表面上に、凸部の厚さが凹部の厚さと同等の光触媒層を形成することでも、光触媒層の表面に凹凸を形成することが理論上は可能であるが、本発明においては採用できない。それは、基板の凹凸形状を反映させて光触媒層に凹凸形状を付与しようとする場合、基板の凹凸形状よりも大きな凹凸形状を有する、あるいは、基板の凹凸形状よりも微細な凹凸形状を有する光触媒層を製膜することは、特に大面積の光触媒材を工業的に生産するためには適さないためである。また、基板の凹凸形状を反映させて光触媒層に凹凸形状を付与しようとする場合、光触媒粒子を含む多孔質膜の製膜時のレベリングによる表面平坦化や凹凸のバラツキを生じる懸念がある。これらのことを鑑みて、本発明では、凸部の厚さを凹部の厚さよりも大きくした光触媒層を、好ましくは光触媒層の凹凸形状よりも小さい凹凸形状、より好ましくは実質的には平面を備えた基板の上に、製膜することが望ましい。こうすることで、水素発生能が高い光触媒層を得ることができるとともに、表面における凹凸形状を再現良く製膜することができ、凹凸のバラツキを抑制することも可能となる。 Theoretically, it is possible to form irregularities on the surface of the photocatalyst layer by forming the surface of the substrate into an uneven shape and forming a photocatalyst layer having a convex portion having a thickness equal to that of the concave portion on the surface of the base material. Is possible, but cannot be adopted in the present invention. When it is intended to give the photocatalyst layer an uneven shape by reflecting the uneven shape of the substrate, the photocatalyst layer has an uneven shape larger than the uneven shape of the substrate or has a finer uneven shape than the uneven shape of the substrate. This is because forming a film is not particularly suitable for industrially producing a large-area photocatalytic material. Further, when trying to give the photocatalyst layer an uneven shape by reflecting the uneven shape of the substrate, there is a concern that the surface may be flattened or the unevenness may vary due to leveling during the formation of the porous film containing the photocatalyst particles. In view of these facts, in the present invention, the photocatalyst layer in which the thickness of the convex portion is larger than the thickness of the concave portion is preferably a concavo-convex shape smaller than the concavo-convex shape of the photocatalyst layer, more preferably substantially a flat surface. It is desirable to form a film on the provided substrate. By doing so, it is possible to obtain a photocatalyst layer having a high hydrogen generating ability, and it is possible to form a film with good reproduction of the uneven shape on the surface, and it is also possible to suppress the variation of the unevenness.
本発明において、凸部１１の厚さ（Ｔ１１）は、光触媒層１が有する複数の凸部１１の厚さの平均値である。光触媒層１が有する凸部１１各々の厚さは、基板２の表面から山頂点又は山頂部１１Ｓまでの距離の平均値である。また、凹部１２の厚さ（Ｔ１２）は、光触媒層１が有する複数の凹部１２の厚さの平均値である。光触媒層１が有する凹部１２各々の厚さは、基板２の表面から谷底点又は谷底部１２Ｂまでの距離の平均値である。図１では、Ｔ１１として、基板２の表面から山頂部１１Ｓまでの最小距離を、Ｔ１２として、基板２の表面から谷底点又は谷底部１２Ｂまでの最大距離を例示する。 In the present invention, the thickness of the convex portion 11 (T 11 ) is an average value of the thicknesses of the plurality of convex portions 11 of the photocatalyst layer 1. The thickness of each of the convex portions 11 of the photocatalyst layer 1 is an average value of the distances from the surface of the substrate 2 to the peak or the peak 11S. The thickness of the recess 12 (T 12 ) is an average value of the thicknesses of the plurality of recesses 12 of the photocatalyst layer 1. The thickness of each of the recesses 12 of the photocatalyst layer 1 is an average value of the distances from the surface of the substrate 2 to the valley bottom point or the valley bottom portion 12B. In FIG. 1, the minimum distance from the surface of the substrate 2 to the peak portion 11S is illustrated as T 11 , and the maximum distance from the surface of the substrate 2 to the valley bottom point or the valley bottom 12B is illustrated as T 12 .
光触媒における凸部および凹部の厚さは、例えば光触媒層（好ましくは光触媒材）の破断面の走査型電子顕微鏡（ＳＥＭ）観察により求めることができる。
具体的には、光触媒層を担持させた光触媒材の山頂部と谷底部を含む破断面をＳＥＭ観察（観察倍率：５００倍）することで、観察箇所５点の山頂部および谷底部それぞれの平均値から求めることができる。
The thickness of the protrusions and recesses in the photocatalyst can be determined, for example, by observing the fracture surface of the photocatalyst layer (preferably the photocatalyst material) with a scanning electron microscope (SEM).
Specifically, by SEM observation (observation magnification: 500 times) of the fracture surface including the peak and valley bottom of the photocatalyst material on which the photocatalyst layer is supported, the average of each of the peak and valley bottom of the five observation points. It can be calculated from the value.
本発明において、凸部１１の厚さ（Ｔ１１）は、５μｍ以上１２０μｍ以下であることが好ましい。凹部１２の厚さ（Ｔ１２）は、０．１μｍ以上２０μｍ以下であることが好ましい。 In the present invention, the thickness (T 11 ) of the convex portion 11 is preferably 5 μm or more and 120 μm or less. The thickness (T 12 ) of the recess 12 is preferably 0.1 μm or more and 20 μm or less.
なお、図１に示す態様では、基板２の表面は凹凸形状であるが、基板２の表面が平滑である場合、すなわち、基板２が光触媒層１に対して平面とみなせる場合、凸部１１の厚さ（Ｔ１１）は、凸部の高さの平均値（Ｈ１１Ｓ０）に等しい。同様に、凹部１２の厚さ（Ｔ１２）は、凹部の高さの平均値（Ｈ１２Ｂ０）に等しい。 In the embodiment shown in FIG. 1, the surface of the substrate 2 has an uneven shape, but when the surface of the substrate 2 is smooth, that is, when the substrate 2 can be regarded as a flat surface with respect to the photocatalyst layer 1, the convex portion 11 The thickness (T 11 ) is equal to the average value of the heights of the protrusions (H 11S0 ). Similarly, the thickness of the recess 12 (T 12 ) is equal to the average height of the recess (H 12B0 ).
凸部のピッチ
本発明において、光触媒層における凸部のピッチは、１０μｍを超え３０００μｍ以下であることが好ましい。ピッチが３０００μｍ以下であると、凹部に水素ガス及び／又は酸素ガスの気泡が保持され難くなり、水分解の逆反応を抑制することができる。また、ピッチが１０μｍより大であると、気泡のサイズ（好ましくは０．１〜１ｍｍ）に対して、光触媒層の凹凸形状が実質的に平面とみなされる可能性が低くなるため、気泡の成長を抑制することができ、水分解により発生した水素ガス及び／又は酸素ガスを光触媒層の表面から速やかに離脱させることができる。光触媒層における凸部のピッチは、２０μｍ以上２０００μｍ以下であることが好ましい。
Pitch of convex portion In the present invention, the pitch of the convex portion in the photocatalyst layer is preferably more than 10 μm and not more than 3000 μm. When the pitch is 3000 μm or less, it becomes difficult for hydrogen gas and / or oxygen gas bubbles to be retained in the recesses, and the reverse reaction of water decomposition can be suppressed. Further, when the pitch is larger than 10 μm, it is less likely that the uneven shape of the photocatalyst layer is considered to be substantially flat with respect to the size of the bubbles (preferably 0.1 to 1 mm), so that the growth of the bubbles Can be suppressed, and hydrogen gas and / or oxygen gas generated by water splitting can be rapidly separated from the surface of the photocatalyst layer. The pitch of the convex portions in the photocatalyst layer is preferably 20 μm or more and 2000 μm or less.
本発明において、光触媒層における凸部のピッチは、例えば以下のように測定される。
凸部と凹部との高低差の測定方法で得られた、ある視野での三次元画像において、任意に選択した複数の凸部の各頂点又は頂上部の間のピッチの平均値を求める。
上記の視野とは異なる視野でさらに幾つかの観察を行い、各視野での光触媒層における凸部のピッチを求める。異なる視野での光触媒層における凸部のピッチの平均値を、光触媒層における凸部のピッチとする。
In the present invention, the pitch of the convex portion in the photocatalyst layer is measured as follows, for example.
In a three-dimensional image in a certain field of view obtained by the method of measuring the height difference between the convex portion and the concave portion, the average value of the pitches between the vertices or the tops of a plurality of arbitrarily selected convex portions is obtained.
Some further observations are made in a field of view different from the above field of view, and the pitch of the convex portion in the photocatalyst layer in each field of view is obtained. The average value of the pitch of the convex portions in the photocatalyst layer in different fields of view is defined as the pitch of the convex portions in the photocatalyst layer.
算術平均高さ（Ｓａ）
本発明において、光触媒層の表面の算術平均高さ（Ｓａ）は、３．０μｍ以上２０μｍ以下であることが好ましい。算術平均高さ（Ｓａ）がこの範囲にあることにより、光触媒層の表面における水素ガス及び／又は酸素ガスの気泡の成長を抑制し、水素ガス及び／又は酸素ガスを光触媒層の表面から速やかに離脱させることが可能となるとともに、水分解により一旦発生した水素および酸素が反応して再び水を生成する逆反応を防止することが可能となる。光触媒層の表面の算術平均高さ（Ｓａ）は、３μｍ以上１０μｍ以下であることが、より好ましい。
Arithmetic mean height (Sa)
In the present invention, the arithmetic mean height (Sa) of the surface of the photocatalyst layer is preferably 3.0 μm or more and 20 μm or less. When the arithmetic average height (Sa) is in this range, the growth of bubbles of hydrogen gas and / or oxygen gas on the surface of the photocatalyst layer is suppressed, and hydrogen gas and / or oxygen gas is rapidly discharged from the surface of the photocatalyst layer. It is possible to separate the gas, and it is possible to prevent a reverse reaction in which hydrogen and oxygen once generated by water decomposition react to generate water again. It is more preferable that the arithmetic mean height (Sa) of the surface of the photocatalyst layer is 3 μm or more and 10 μm or less.
本発明において、光触媒層の表面の算術平均高さ（Ｓａ）は、例えば以下のように測定される。
凸部と凹部との高低差の測定方法で得られた、ある視野での三次元画像を用い、ＩＳＯ ２５１７８に準拠して、光触媒層の表面の算術平均高さ（Ｓａ）を求める。
上記の視野とは異なる視野でさらに幾つかの観察を行い、各視野での光触媒層の表面の算術平均高さ（Ｓａ）を求める。異なる視野での光触媒層の表面の算術平均高さ（Ｓａ）の平均値を、光触媒層の表面の算術平均高さ（Ｓａ）とする。
In the present invention, the arithmetic mean height (Sa) of the surface of the photocatalyst layer is measured, for example, as follows.
The arithmetic mean height (Sa) of the surface of the photocatalyst layer is determined according to ISO 25178 using a three-dimensional image in a certain field of view obtained by the method of measuring the height difference between the convex portion and the concave portion.
Some further observations are made in a field of view different from the above field of view, and the arithmetic mean height (Sa) of the surface of the photocatalyst layer in each field of view is obtained. The average value of the arithmetic mean height (Sa) of the surface of the photocatalyst layer in different fields of view is defined as the arithmetic mean height (Sa) of the surface of the photocatalyst layer.
多孔質構造
光触媒層１は、後記する光触媒粒子と親水性バインダーとを含んでなる多孔質膜である。したがって、光触媒層１は細孔６を有する（図２参照）。細孔６は、光触媒粒子などの粒子成分の間に配置される。細孔６を介し、光触媒層１の表面だけでなく、その内部に配置される光触媒粒子も、水及び光と接触することが可能となる。また、細孔６を介し、水や、光照射による水の光分解で生じた水素ガス及び酸素ガスが拡散可能とされる。細孔径は１ｎｍ以上１０μｍ以下であることが好ましい。
The porous structure photocatalyst layer 1 is a porous film including the photocatalyst particles described later and a hydrophilic binder. Therefore, the photocatalyst layer 1 has pores 6 (see FIG. 2). The pores 6 are arranged between particle components such as photocatalytic particles. Through the pores 6, not only the surface of the photocatalyst layer 1 but also the photocatalyst particles arranged inside the photocatalyst layer 1 can come into contact with water and light. Further, hydrogen gas and oxygen gas generated by photodecomposition of water and water by light irradiation can be diffused through the pores 6. The pore diameter is preferably 1 nm or more and 10 μm or less.
細孔径は、細孔分布測定により求めることができる。例えば、光触媒層を基板から剥離した粉末試料の、細孔分布測定装置（例えば、マイクロトラックベル社製“Ｂｅｌｓｏｒｐ ｍｉｎｉ”）を用いて測定される窒素ガスの吸着等温線から得られる微分細孔容積分布の最強ピーク値として、細孔径を求めることができる。 The pore diameter can be determined by measuring the pore distribution. For example, the differential pore volume obtained from the adsorption isotherm of nitrogen gas measured using a pore distribution measuring device (for example, "Belsorb mini" manufactured by Microtrac Bell) of a powder sample obtained by peeling the photocatalyst layer from the substrate. The pore diameter can be obtained as the strongest peak value of the distribution.
生成ガス
図２は、山型の凹凸形状を有する光触媒層において、凸部の頂点近くの一部を拡大した模式図である。光触媒層は、後記する光触媒粒子３および親水性バインダー４を含む。図２に示すように、光触媒層の表面が山型の凹凸形状を有することにより、光触媒材を水５と接触させた際、光触媒層の表面における生成ガス、すなわち水素ガス（Ｈ２）及び／又は酸素ガス（Ｏ２）の気泡の成長は、山型形状の傾斜面により、抑制されるものと考えられる。つまり、気泡が成長する前に、水素ガス（Ｈ２）及び／又は酸素ガス（Ｏ２）は、光触媒層の表面から速やかに離脱する。
本発明において、光触媒層の表面から離脱した生成ガスの気泡のサイズは、０．０１ｍｍ〜０．１ｍｍであることが好ましい。気泡のサイズは、例えば以下のように測定される。
光触媒材を水中に浸漬（水深２ｃｍ）させ、３００Ｗキセノンランプ（Ｃｅｒｍａｘ）を用いて紫外および可視光を光触媒層表面の５ｃｍ上方から照射する。光触媒層表面から生成する気泡を、レーザー顕微鏡（ＯＬＳ−５２００、オリンパス製、光学倍率５倍の光学レンズ装着）によって観察し、生成する気泡２０個の直径の平均値を気泡サイズとする。
The generated gas FIG. 2 is an enlarged schematic view of a part of the photocatalyst layer having a mountain-shaped uneven shape near the apex of the convex portion. The photocatalyst layer contains the photocatalyst particles 3 and the hydrophilic binder 4 described later. As shown in FIG. 2, since the surface of the photocatalyst layer has a chevron-shaped uneven shape, when the photocatalyst material is brought into contact with water 5, the generated gas on the surface of the photocatalyst layer, that is, hydrogen gas (H 2 ) and / Alternatively, it is considered that the growth of oxygen gas (O 2 ) bubbles is suppressed by the chevron-shaped inclined surface. That is, the hydrogen gas (H 2 ) and / or the oxygen gas (O 2 ) rapidly separate from the surface of the photocatalyst layer before the bubbles grow.
In the present invention, the size of the bubbles of the produced gas separated from the surface of the photocatalyst layer is preferably 0.01 mm to 0.1 mm. The size of the bubbles is measured, for example, as follows.
The photocatalyst material is immersed in water (water depth 2 cm), and ultraviolet and visible light are irradiated from 5 cm above the surface of the photocatalyst layer using a 300 W xenon lamp (Cermax). The bubbles generated from the surface of the photocatalyst layer are observed with a laser microscope (OLS-5200, manufactured by Olympus, equipped with an optical lens having an optical magnification of 5 times), and the average value of the diameters of the 20 generated bubbles is defined as the bubble size.
光触媒粒子
光触媒層１に含まれる光触媒粒子は、水の光分解反応を触媒可能なものであればよい。水の光分解反応を触媒可能な光触媒粒子である限りにおいて、任意の形状、大きさ、厚み等の物理的特性を有する光触媒粒子を用いることができる。光触媒粒子の形状は、例えば、粒状、板状、または針状であってよい。
Photocatalytic particles The photocatalytic particles contained in the photocatalyst layer 1 may be any particles capable of catalyzing the photocatalytic reaction of water. As long as the photocatalytic particles can catalyze the photocatalytic reaction of water, photocatalytic particles having physical properties such as an arbitrary shape, size, and thickness can be used. The shape of the photocatalyst particles may be, for example, granular, plate-like, or needle-like.
光触媒粒子の一次粒子径は、１０ｎｍ以上５０μｍ以下であることが好ましい。このような小さな粒径とすることで、光触媒粒子において、水と接触可能な単位重量当たりの表面積が大きくなる。これにより、水の還元又は酸化反応サイトが増加し、その結果、高効率な水素又は酸素発生が可能となる。 The primary particle size of the photocatalyst particles is preferably 10 nm or more and 50 μm or less. With such a small particle size, the surface area of the photocatalytic particles per unit weight that can come into contact with water is increased. This increases the reduction or oxidation reaction sites of water, resulting in highly efficient hydrogen or oxygen evolution.
光触媒粒子の平均一次粒子径は、走査型電子顕微鏡（例えば、ＳＵ−８２２０、日立ハイテク製）を用いて、倍率２０００倍、２μｍ角の視野で二次電子像を観察した際の結晶粒子２０個の円形近似による平均値として求めることができる。 The average primary particle size of the photocatalyst particles is 20 crystal particles when the secondary electron image is observed with a field of magnification of 2000 times and 2 μm square using a scanning electron microscope (for example, SU-8220, manufactured by Hitachi High-Tech). It can be obtained as an average value by circular approximation of.
本発明で用いられる光触媒粒子の具体例を以下に示す。本明細書では、後記のとおり、水分解の作用機序および光触媒粒子の光励起のされ方に応じて、光触媒粒子を、一段階励起により水を水素と酸素に光分解できる光触媒粒子、および二段階励起により水を光分解し水素あるいは酸素を生成できる光触媒粒子に分類分けし、この順で説明する。 Specific examples of the photocatalytic particles used in the present invention are shown below. In the present specification, as described later, the photocatalytic particles are photocatalytic particles that can photocatalyst water into hydrogen and oxygen by one-step excitation, and two-step photocatalytic particles, depending on the mechanism of action of water splitting and how the photocatalytic particles are photoexcited. The particles are classified into photocatalytic particles capable of photocatalyst water by excitation to generate hydrogen or oxygen, and will be described in this order.
（一段階励起により水を水素と酸素に光分解できる光触媒粒子）
水素発生用可視光応答型光触媒粒子は、光学的バンドギャップを有する半導体粒子である。光触媒粒子が紫外光あるいは可視光を吸収することで、光触媒粒子におけるバンド間遷移等の電子遷移により、伝導帯あるいはバンドギャップ内に存在する電子アクセプター準位に励起電子を生じ、かつ価電子帯あるいはバンドギャップ内に存在する電子ドナー準位に励起正孔を生じる。一段階励起により水を水素と酸素に光分解できる光触媒粒子とは、この励起電子および励起正孔のそれぞれが反応対象物を還元および酸化することが可能な光触媒材料である。つまり、一段階励起により水を水素と酸素に光分解できる光触媒粒子は、例えば、紫外光あるいは可視光線を照射することで生成する励起電子が、水を還元して水素を、かつ、水を酸化して酸素を生成可能な光触媒材料である。この光触媒粒子の伝導帯あるいはバンドギャップ内に存在する電子アクセプター準位は、例えば、水の還元電位（０Ｖ ｖｓ．ＮＨＥ（標準水素電極電位）ａｔ ｐＨ＝０）よりも負な位置にあり、価電子帯あるいはバンドギャップ内に存在する電子ドナー準位は、例えば、水の酸化電位（＋１．２３Ｖ ｖｓ．ＮＨＥ（標準水素電極電位）ａｔ ｐＨ＝０）よりも正な位置にある。一段階励起により水を水素と酸素に光分解できる光触媒粒子の好ましい例としては、紫外応答型光触媒としては、ＴｉＯ２, ＳｒＴｉＯ３（Ｇａ３＋、Ｓｃ３＋、Ｙ３＋、Ａｌ３＋、Ｍｇ２＋等のドープ体を含む）、ＮａＴａＯ３（Ｌａ３＋等のドープ体を含む：）、Ｋ２Ｎｂ６Ｏ１７等の層状金属酸化物が挙げられ、可視光応答型光触媒としては、Ｒｈ３＋ドープＳｒＴｉＯ３（Ｓｂ５＋またはＬａ３＋の共ドープ体を含む）等の金属酸化物、ＧａＮ−ＺｎＯ固溶体やＭｇ２＋ドープＬａＴａＯ２Ｎ等の金属酸窒化物、金属酸硫化物等が好適に用いられるが、上記のバンド構造を満たし、水を一段階で分解して水素と酸素を生成するものであれば特に限定されない。
(Photocatalytic particles that can photoly decompose water into hydrogen and oxygen by one-step excitation)
The visible light responsive photocatalytic particles for hydrogen generation are semiconductor particles having an optical bandgap. When the photocatalyst particles absorb ultraviolet light or visible light, electron transitions such as band-to-band transitions in the photocatalyst particles generate excitation electrons at the electron acceptor level existing in the conduction band or band gap, and the valence band or the valence band or Excited holes are generated at the electron donor level existing in the band gap. Photocatalytic particles capable of photocatalytically decomposing water into hydrogen and oxygen by one-step excitation are photocatalytic materials in which each of these excited electrons and excited holes can reduce and oxidize the reaction object. That is, in the photocatalytic particles capable of photodegrading water into hydrogen and oxygen by one-step excitation, for example, excited electrons generated by irradiating ultraviolet light or visible light reduce water to oxidize hydrogen and oxidize water. It is a photocatalytic material capable of generating oxygen. The electron acceptor level existing in the conduction band or band gap of the photocatalyst particles is, for example, at a position more negative than the reduction potential of water (0V vs. NHE (standard hydrogen electrode potential) at pH = 0) and has a valence. The electron donor level existing in the electron band or band gap is, for example, at a position more positive than the oxidation potential of water (+1.23 V vs. NHE (standard hydrogen electrode potential) at pH = 0). Preferred examples of photocatalytic particles capable of photocatalyst water into hydrogen and oxygen by one-step excitation include TiO 2 , SrTIO 3 (Ga 3+ , Sc 3+ , Y 3+ , Al 3+ , Mg 2+, etc.) as ultraviolet-responsive photocatalysts. comprises doped body) :) containing NaTaO 3 (La 3+, etc. doped body, the layered metal oxides such as K 2 Nb 6 O 17, and examples of the visible-light-responsive photocatalyst, Rh 3+ doped SrTiO 3 ( sb 5+ or a co-doping of La 3+) metal oxide such as, GaN-ZnO solid solution or Mg 2+ doped LaTaO metal oxynitride such as 2 N, a metal oxysulfide, etc. are suitably used, the It is not particularly limited as long as it satisfies the band structure and decomposes water in one step to generate hydrogen and oxygen.
（二段階励起により水を光分解し水素あるいは酸素を生成できる光触媒粒子）
可視光応答型光触媒粒子
二段階励起により水を光分解し水素あるいは酸素を生成できる光触媒粒子とは、いわゆるＺスキームモデルで水を分解できる光触媒粒子をいう。Ｚスキームモデルでは、例えば可視光の照射により、水素生成用可視光応答型光触媒粒子が生成した励起電子が水を還元して水素を生成し、酸素生成用可視光応答型光触媒粒子が生成した励起正孔が水を酸化して酸素を生成する。二段階励起により水を光分解し水素あるいは酸素を生成できる光触媒粒子として、例えばＷＯ２０１４／０４６３０５号公報に記載のいわゆるＺスキーム型光触媒粒子が挙げられる。
(Photocatalytic particles capable of photodecomposing water to generate hydrogen or oxygen by two-step excitation)
Visible light-responsive photocatalytic particles Photocatalytic particles that can photocatalyst water to generate hydrogen or oxygen by two-step excitation are photocatalytic particles that can decompose water using the so-called Z scheme model. In the Z scheme model, for example, by irradiation with visible light, excited electrons generated by visible light responsive photocatalyst particles for hydrogen generation reduce water to generate hydrogen, and excitation generated by visible light responsive photocatalyst particles for oxygen generation. Holes oxidize water to produce oxygen. Examples of photocatalytic particles capable of photocatalyst water to generate hydrogen or oxygen by two-step excitation include so-called Z-scheme type photocatalytic particles described in WO2014 / 046305.
水素発生用可視光応答型光触媒粒子
水素発生用可視光応答型光触媒粒子は、光学的バンドギャップを有する半導体粒子である。水素発生用可視光応答型光触媒粒子が可視光を吸収することで、水素発生用可視光応答型光触媒粒子におけるバンド間遷移等の電子遷移により、伝導帯あるいはバンドギャップ内に存在する電子アクセプター準位に励起電子を生じ、かつ価電子帯あるいはバンドギャップ内に存在する電子ドナー準位に励起正孔を生じる。水素発生用可視光応答型光触媒粒子とは、この励起電子および励起正孔のそれぞれが反応対象物を還元および酸化することが可能な光触媒材料である。つまり、水素発生用可視光応答型光触媒粒子は、例えば、可視光線を照射することで生成する励起電子が、水を還元して水素を生成可能な光触媒材料である。水素発生用可視光応答型光触媒粒子の伝導帯あるいはバンドギャップ内に存在する電子アクセプター準位は、例えば、水の還元電位（０Ｖ ｖｓ．ＮＨＥ（標準水素電極電位）ａｔ ｐＨ＝０）よりも負な位置にある。また、水素発生用可視光応答型光触媒粒子の価電子帯あるいはバンドギャップ内に存在する電子ドナー準位は、例えば、第２の光触媒粒子の伝導帯位置よりも正な位置にある。
Visible light responsive photocatalyst particles for hydrogen generation Visible light responsive photocatalyst particles for hydrogen generation are semiconductor particles having an optical bandgap. When the visible light responsive photocatalyst particles for hydrogen generation absorb visible light, the electron acceptor level existing in the conduction band or band gap due to electron transitions such as band-to-band transitions in the visible light responsive photocatalyst particles for hydrogen generation. Generates excitation electrons in, and also generates excitation holes in the electron donor level existing in the valence band or bandgap. The visible light responsive photocatalytic particles for hydrogen generation are photocatalytic materials in which the excited electrons and the excited holes can each reduce and oxidize the reaction target. That is, the visible light-responsive photocatalytic particles for hydrogen generation are, for example, photocatalytic materials in which excited electrons generated by irradiating visible light can reduce water to generate hydrogen. The electron acceptor level existing in the conduction band or band gap of the visible light responsive photocatalyst particles for hydrogen generation is, for example, more negative than the reduction potential of water (0 V vs. NHE (standard hydrogen electrode potential) at pH = 0). It is in a good position. Further, the electron donor level existing in the valence band or band gap of the visible light responsive photocatalyst particles for hydrogen generation is, for example, at a position more positive than the conduction band position of the second photocatalyst particles.
水素発生用可視光応答型光触媒粒子の好ましい例としては、ＲｈドープＳｒＴｉＯ３（ＳｒＴｉ１−ｘＲｈｘＯ３：ｘ＝０．００２〜０．１）、ＩｒドープＳｒＴｉＯ３（ＳｒＴｉ１−ｘＩｒｘＯ３：ｘ＝０．００２〜０．１）、ＣｒドープＳｒＴｉＯ３（ＳｒＴｉ１−ｘＣｒｘＯ３：ｘ＝０．００２〜０．１）、Ｃｒ及びＴａドープＳｒＴｉＯ３（ＳｒＴｉ１−ｘ―ｙＣｒｘＴａｙＯ３：ｘ＝０．００２〜０．１、ｙ＝０．００２〜０．１）、Ｌａ及びＲｈドープＳｒＴｉＯ３（Ｓｒ１−ｘＬａｘＴｉ１―ｙＲｈｙＯ３：ｘ＝０．００５〜０．２、ｙ＝０．００５〜０．２）等の遷移金属あるいは貴金属の少なくとも１種類がドープされたペロブスカイト型ＳｒＴｉＯ３、Ｃｕ２Ｏ、ＣｕＯ、ＣａＦｅ２Ｏ４、ＮｉＯ、Ｂｉ２Ｏ３、ＢｉＯＸ（Ｘ＝Ｃｌ，Ｂｒ，Ｉ）、ＧａＮ−ＺｎＯ固溶体、ＬａＴｉＯ２Ｎ、ＢａＴａＯ２Ｎ、ＢａＮｂＯ２Ｎ、ＴａＯＮ、Ｔａ３Ｎ５、Ｇｅ３Ｎ４等の遷移金属あるいは典型金属を含有する酸窒化物あるいは窒化物、ＣｕＧａＳ２、ＣｕＩｎＳ２、Ｃｕ（Ｇａ，Ｉｎ）Ｓ２、ＣｕＧａＳｅ２、ＣｕＩｎＳｅ２、Ｃｕ（Ｇａ，Ｉｎ）Ｓｅ２、Ｃｕ２ＺｎＳｎＳ４（ＣＺＴＳ）、Ｃｕ２ＺｎＳｎ（Ｓ，Ｓｅ）４等のＧａ、Ｉｎ、Ａｌ等の典型金属を含む銅複合硫セレン化物、Ｌａ５Ｔｉ２ＣｕＳ５Ｏ７、Ｌａ５Ｔｉ２ＡｇＳ５Ｏ７、Ｌａ５Ｔｉ２ＣｕＳｅ５Ｏ７、Ｌａ５Ｔｉ２ＡｇＳｅ５Ｏ７等の酸硫セレン化物からなる群から選択される１種以上が挙げられる。 Preferred examples of visible light responsive photocatalyst particles for hydrogen generation are Rh-doped SrTIO 3 (SrTi 1-x Rh x O 3 : x = 0.002-0.1) and Ir-doped SrTiO 3 (SrTi 1-x Ir). x O3: x = 0.002 to 0.1), Cr-doped SrTIO 3 (SrTi 1-x Cr x O 3 : x = 0.002 to 0.1), Cr and Ta-doped SrTIO 3 (SrTi 1-x) -y Cr x Ta y O 3: x = 0.002~0.1, y = 0.002~0.1), La and Rh-doped SrTiO 3 (Sr 1-x La x Ti 1-y Rh y O 3 : Perovskite type SrTIO 3 , Cu 2 O, CuO, CaFe 2 O doped with at least one of a transition metal such as x = 0.005 to 0.2, y = 0.005 to 0.2) or a noble metal. 4 , NiO, Bi 2 O 3 , BiOX (X = Cl, Br, I), GaN-ZnO solid solution, LaTIO 2 N, BaTaO 2 N, BaNbO 2 N, TaON, Ta 3 N 5 , Ge 3 N 4, etc. Acid nitrides or nitrides containing transition metals or main group elements, CuGaS 2 , CuInS 2 , Cu (Ga, In) S 2 , CuGaSe 2 , CuInSe 2 , Cu (Ga, In) Se 2 , Cu 2 ZnSnS 4 ( CZTS), Cu 2 ZnSn (S, Se) 4, etc. Copper composite sulfur selenide containing typical metals such as Ga, In, Al, La 5 Ti 2 CuS 5 O 7 , La 5 Ti 2 AgS 5 O 7 , La One or more selected from the group consisting of acid sulfate selenium products such as 5 Ti 2 CuSe 5 O 7 and La 5 Ti 2 AgSe 5 O 7 can be mentioned.
酸素発生用可視光応答型光触媒粒子
酸素発生用可視光応答型光触媒粒子は、光学的バンドギャップを有する半導体粒子である。酸素発生用可視光応答型光触媒粒子が可視光を吸収することで、酸素発生用可視光応答型光触媒粒子におけるバンド間遷移等の電子遷移により、伝導帯に励起電子を生じ、かつ価電子帯に励起正孔が生じる。酸素発生用可視光応答型光触媒粒子とは、この励起電子および励起正孔のそれぞれが反応対象物を還元および酸化することが可能な光触媒材料である。つまり、酸素発生用可視光応答型光触媒粒子は、例えば、可視光線を照射することで生成する励起正孔が、水を酸化して酸素を生成可能な光触媒材料である。酸素発生用可視光応答型光触媒粒子の価電子帯は、例えば、水の酸化電位（＋１．２３Ｖ ｖｓ．ＮＨＥ（標準水素電極電位）ａｔ ｐＨ＝０）よりも正な位置にある。また、酸素発生用可視光応答型光触媒粒子の伝導帯は、例えば水素発生用可視光応答型光触媒粒子の価電子帯位置よりも負な位置にある。
Visible light responsive photocatalyst particles for oxygen generation Visible light responsive photocatalyst particles for oxygen evolution are semiconductor particles having an optical bandgap. When the visible light responsive photocatalyst particles for oxygen generation absorb visible light, excited electrons are generated in the conduction band and in the valence band due to electron transitions such as band-to-band transitions in the visible light responsive photocatalyst particles for oxygen generation. Excited holes are generated. Visible light-responsive photocatalytic particles for oxygen evolution are photocatalytic materials in which excited electrons and holes can each reduce and oxidize the reaction target. That is, the visible light-responsive photocatalytic particles for oxygen evolution are, for example, photocatalytic materials in which excited holes generated by irradiation with visible light can oxidize water to generate oxygen. The valence band of the visible light responsive photocatalytic particles for oxygen evolution is, for example, at a position more positive than the oxidation potential of water (+1.23 V vs. NHE (standard hydrogen electrode potential) at pH = 0). Further, the conduction band of the visible light responsive photocatalyst particles for oxygen generation is located at a position more negative than the valence band position of the visible light responsive photocatalyst particles for hydrogen generation, for example.
酸素発生用可視光応答型光触媒粒子の好ましい例としては、ＢｉＶＯ４、ＸドープＢｉＶＯ４（Ｘ：Ｍｏ，Ｗ）、ＳｎＮｂ２Ｏ６、ＷＯ３、Ｂｉ２ＷＯ６、Ｆｅ２ＴｉＯ５、Ｆｅ２Ｏ３、Ｂｉ２ＭｏＯ６、ＧａＮ−ＺｎＯ固溶体、ＬａＴｉＯ２Ｎ、ＢａＴａＯ２Ｎ、ＢａＮｂＯ２Ｎ、ＴａＯＮ、Ｔａ３Ｎ５、Ｇｅ３Ｎ４等の遷移金属あるいは典型金属を含有する酸窒化物あるいは窒化物からなる群から選択される一種以上が挙げられる。 Preferred examples of visible light responsive photocatalytic particles for oxygen generation are BiVO 4 , X-doped BiVO 4 (X: Mo, W), SnNb 2 O 6 , WO 3 , Bi 2 WO 6 , Fe 2 TiO 5 , Fe 2. Oxynitrides containing transition metals or typical metals such as O 3 , Bi 2 MoO 6 , GaN-ZnO solid solution, LaTIO 2 N, BaTaO 2 N, BaNbO 2 N, TaON, Ta 3 N 5 , Ge 3 N 4, etc. One or more selected from the group consisting of nitrides can be mentioned.
光触媒層中に含まれる固形分全体に対する光触媒粒子の含有割合は、１ｗｔ％以上９９ｗｔ％以下であることが好ましく、光触媒粒子の種類、形態などに応じて適宜決定すればよい。例えば、一段階励起により水を水素と酸素に光分解できる光触媒粒子の含有割合は５０ｗｔ％〜９０ｗｔ％であることが好ましく、二段階励起により水を光分解し水素あるいは酸素を生成できる光触媒粒子の含有割合は３０ｗｔ％〜９０ｗｔ％であることが好ましい。 The content ratio of the photocatalyst particles to the total solid content contained in the photocatalyst layer is preferably 1 wt% or more and 99 wt% or less, and may be appropriately determined according to the type and form of the photocatalyst particles. For example, the content ratio of the photocatalytic particles capable of photodecomposing water into hydrogen and oxygen by one-step excitation is preferably 50 wt% to 90 wt%, and the content of the photocatalytic particles capable of photocatalyst water by two-step excitation to generate hydrogen or oxygen. The content ratio is preferably 30 wt% to 90 wt%.
光触媒粒子の助触媒
本発明において、光触媒粒子の表面に助触媒を担持させることができる。これにより、水の還元および酸化反応が促進され、水素および酸素の生成効率が向上する。水素発生用可視光応答型光触媒粒子の助触媒としては、白金、ルテニウム、イリジウム、ロジウム等の金属粒子、これら金属粒子の酸化物または水酸化物、これら金属酸化物または水酸化物とＣｒ、Ｚｒ、Ｔａ、Ｔｉ、Ｓｉとの複合体を用いることがでる。助触媒を光触媒粒子１の表面に担持させることにより、水の還元反応における活性化エネルギーを減少させることが可能となるため、速やかな水素の発生が可能となる。酸素発生用可視光応答型光触媒粒子２０の助触媒としては、Ｍｎ、Ｆｅ、Ｃｏ、Ｉｒ、Ｒｕ、Ｎｉ等の金属、これらの金属を混合させた金属酸化物、金属水酸化物もしくは金属リン酸塩からなる粒子を用いることができる。
Cocatalyst of photocatalyst particles In the present invention, a cocatalyst can be supported on the surface of photocatalyst particles. This promotes the reduction and oxidation reactions of water and improves the efficiency of hydrogen and oxygen production. Examples of the cocatalyst of the visible light responsive photocatalyst particles for hydrogen generation include metal particles such as platinum, ruthenium, iridium, and rhodium, oxides or hydroxides of these metal particles, these metal oxides or hydroxides, and Cr, Zr. , Ta, Ti, Si and composites can be used. By supporting the cocatalyst on the surface of the photocatalyst particles 1, it is possible to reduce the activation energy in the reduction reaction of water, so that hydrogen can be rapidly generated. Examples of the cocatalyst of the visible light responsive photocatalyst particles 20 for oxygen generation include metals such as Mn, Fe, Co, Ir, Ru, and Ni, metal oxides obtained by mixing these metals, metal hydroxides, or metal phosphates. Particles made of salt can be used.
これら助触媒の平均一次粒子径は１０ｎｍ未満であることが好ましく、さらに好ましくは５ｎｍ以下である。平均一次粒子径を小さくすることにより、水素および酸素発生反応の活性点として効率的に機能させることができる。 The average primary particle size of these cocatalysts is preferably less than 10 nm, more preferably 5 nm or less. By reducing the average primary particle size, it can efficiently function as an active site for hydrogen and oxygen evolution reactions.
助触媒の平均一次粒子径は、光触媒粒子の平均一次粒子径の測定方法と同様の方法で求めることができる。すなわち、助触媒の平均一次粒子径は、走査型電子顕微鏡（例えば、ＳＵ−８２２０、日立ハイテク製）を用いて、倍率２０００倍、２μｍ角の視野で二次電子像を観察した際の結晶粒子２０個の円形近似による平均値として求めることができる。 The average primary particle size of the cocatalyst can be obtained by the same method as the method for measuring the average primary particle size of the photocatalyst particles. That is, the average primary particle size of the co-catalyst is the crystal particles when the secondary electron image is observed with a field of view of 2000 times magnification and 2 μm square using a scanning electron microscope (for example, SU-8220, manufactured by Hitachi High-Tech). It can be obtained as an average value by 20 circular approximations.
助触媒の濃度は、光触媒に対して、重量当たりの濃度（重量パーセント）として、０．０１〜５重量％が適している。助触媒の濃度をこの範囲内とすることで、助触媒としての効果が望ましく発揮され、あるいは、光触媒粒子の表面に助触媒が適量担持されているため、助触媒により光触媒の光吸収が阻害されるリスクが無い。 The concentration of the cocatalyst is preferably 0.01 to 5% by weight as the concentration per weight (% by weight) with respect to the photocatalyst. By setting the concentration of the co-catalyst within this range, the effect as a co-catalyst is desirablely exhibited, or because an appropriate amount of the co-catalyst is supported on the surface of the photocatalyst particles, the photocatalyst inhibits the light absorption of the photocatalyst. There is no risk of
親水性バインダー
光触媒層１は親水性バインダー４を含む。親水性バインダー４は、光触媒粒子３を結着して、光触媒層１、ひいては光触媒材１００の耐久性を向上させる。さらに、親水性バインダー４は、その親水性により、光触媒層１の内部で生成された水素ガス及び／又は酸素ガスの気泡の光触媒層１表面への移動を助ける。光触媒層１の表面に到達した水素ガス及び／又は酸素ガスの気泡は、上述したとおり、光触媒層１が有する特別な表面構造により、すなわち凹凸形状の傾斜面または垂直面により、気泡が成長する前に表面からスムーズに放出される。このように、本発明の光触媒材にあっては、光触媒層に含まれる親水性バインダーによる作用と、光触媒層の特定の表面形状による作用とが相まって発揮され、高い効率で水を光分解することが可能となり、高い水素発生能を有する。
Hydrophilic binder The photocatalyst layer 1 contains a hydrophilic binder 4. The hydrophilic binder 4 binds the photocatalyst particles 3 to improve the durability of the photocatalyst layer 1 and thus the photocatalyst material 100. Further, the hydrophilic binder 4 assists the movement of hydrogen gas and / or oxygen gas generated inside the photocatalyst layer 1 to the surface of the photocatalyst layer 1 due to its hydrophilicity. As described above, the hydrogen gas and / or oxygen gas bubbles that have reached the surface of the photocatalyst layer 1 are before the bubbles grow due to the special surface structure of the photocatalyst layer 1, that is, due to the uneven inclined surface or vertical surface. Is smoothly discharged from the surface. As described above, in the photocatalyst material of the present invention, the action of the hydrophilic binder contained in the photocatalyst layer and the action of the specific surface shape of the photocatalyst layer are exhibited in combination, and water is photodecomposed with high efficiency. It has a high ability to generate hydrogen.
親水性バインダーは、Ｓｉ、Ｔｉ、Ｚｒ、Ｔａ、Ｎｂ、Ｆｅ、Ｓｎ等の金属を含む酸化物、水酸化物または複合酸化物であることが好ましい。親水性バインダーは、光触媒層１が基板２に密に固定化された場合において、光触媒層表面の水接触角が２０度以下となるような親水性を有することが好ましい。 The hydrophilic binder is preferably an oxide containing a metal such as Si, Ti, Zr, Ta, Nb, Fe or Sn, a hydroxide or a composite oxide. The hydrophilic binder preferably has hydrophilicity such that the water contact angle on the surface of the photocatalyst layer is 20 degrees or less when the photocatalyst layer 1 is densely immobilized on the substrate 2.
親水性バインダーはいかなる形状であってもよく、例えば、粒状あるいは被膜状であってよい。ここで、親水性バインダーが被膜状であるとは、光触媒粒子表面上に、明確な粒界を有する粒子としてではなく、無定形の連続的な被膜として親水性バインダーが担持されている状態を表す。ただし、光触媒全面を親水性バインダー被膜が覆うと、光触媒活性表面が失われてしまうことから、親水性バインダーに被覆されていない光触媒表面も有することが重要である。光触媒粒子に担持された親水性バインダーが被膜状の場合、その厚さは１ｎｍ以上１００ｎｍ以下であることが好ましい。厚さは、たとえば、被膜表面を透過型電子顕微鏡観察にて観察した際の１０点の平均値として求めることができる。親水性バインダーが粒状の場合、その平均一次粒子径は１ｎｍ以上１０μｍ以下であることが好ましい。平均一次粒子径は、例えば、粒状物または被膜状物を、走査型電子顕微鏡（例えば、ＳＵ−８２２０、日立ハイテク製）を用いて、倍率２００００倍、２００ｎｍ角の視野で二次電子像を観察した際の結晶粒子１０個の円形近似による平均値として求めることができる。 The hydrophilic binder may have any shape, for example, granular or film-like. Here, the fact that the hydrophilic binder is in the form of a film means that the hydrophilic binder is supported on the surface of the photocatalyst particles as an amorphous continuous film, not as particles having clear grain boundaries. .. However, if the entire surface of the photocatalyst is covered with the hydrophilic binder film, the photocatalyst active surface is lost. Therefore, it is important to have a photocatalyst surface that is not coated with the hydrophilic binder. When the hydrophilic binder supported on the photocatalyst particles is in the form of a film, the thickness thereof is preferably 1 nm or more and 100 nm or less. The thickness can be determined, for example, as an average value of 10 points when the surface of the coating film is observed by a transmission electron microscope. When the hydrophilic binder is granular, its average primary particle size is preferably 1 nm or more and 10 μm or less. For the average primary particle size, for example, a granular or film-like material is observed with a scanning electron microscope (for example, SU-8220, manufactured by Hitachi High-Tech) at a magnification of 20000 times and a secondary electron image in a field of view of 200 nm square. It can be obtained as an average value by circular approximation of 10 crystal particles.
親水性バインダーが上述のような厚さ、平均一次粒子径を有することにより、光触媒層において、光触媒粒子に可視光を効果的に照射することが可能となる。また、光触媒層において、例えば、親水性バインダーと光触媒粒子とを良好に接触させることが可能となる。また、光触媒層に適切な細孔を形成することができる。 When the hydrophilic binder has the above-mentioned thickness and average primary particle diameter, it is possible to effectively irradiate the photocatalyst particles with visible light in the photocatalyst layer. Further, in the photocatalyst layer, for example, the hydrophilic binder and the photocatalyst particles can be brought into good contact with each other. In addition, appropriate pores can be formed in the photocatalyst layer.
本発明において、光触媒層は、光触媒粒子間における電気的接続点を減らさない程度の量の親水性バインダーを含むことが好ましい。また光触媒層は、光触媒粒子の光吸収を妨げない程度の量の親水性バインダーを含むことが好ましい。また親水性バインダーの含有量は、光触媒層に細孔を形成可能な範囲で適宜設定することが好ましい。光触媒層中に含まれる固形分全体に対する親水性バインダーの含有割合は、１ｗｔ％以上９９ｗｔ％以下であることが好ましい。例えば、親水性バインダーとしてＳｉＯ２粒子を用いる場合、その含有割合は１０ｗｔ％〜５０ｗｔ％であることが好ましい。 In the present invention, the photocatalyst layer preferably contains an amount of hydrophilic binder that does not reduce the electrical connection points between the photocatalyst particles. Further, the photocatalyst layer preferably contains an amount of hydrophilic binder that does not interfere with the light absorption of the photocatalyst particles. Further, the content of the hydrophilic binder is preferably set appropriately within a range in which pores can be formed in the photocatalyst layer. The content ratio of the hydrophilic binder to the total solid content contained in the photocatalyst layer is preferably 1 wt% or more and 99 wt% or less. For example, when SiO 2 particles are used as the hydrophilic binder, the content ratio thereof is preferably 10 wt% to 50 wt%.
導電性粒子
本発明において、光触媒層は導電性粒子を含んでいてもよい。導電性粒子は、水の光分解反応が効率的に起こることを可能にするものであればよい。例えば、特開２０１７−１２４３９３号公報に記載されるような、水素発生用可視光応答型光触媒粒子と、酸素発生用可視光応答型光触媒粒子との間に導電性粒子が接続された光触媒粒子にあっては、導電性粒子は、水素発生用可視光応答型光触媒粒子の価電子帯上端の電子エネルギー準位よりも負な位置であり酸素発生用可視光応答型光触媒粒子の伝導帯下端の電子エネルギー準位よりも正な位置にフェルミ準位を有しており、電子および正孔を貯蔵可能な、導電性を有する粒子である。このような導電性粒子を用いることで、電荷再結合反応により、水素発生用可視光応答型光触媒粒子内で生成した光励起正孔および酸素発生用可視光応答型光触媒粒子内で生成した光励起電子を消滅させ、水素発生用可視光応答型光触媒粒子の伝導帯で生成した光励起電子による水の還元反応の効率を高めることができるものと考えられる。その結果、光触媒材による水の光分解効率、水素発生能を向上させることができる。
Conductive Particles In the present invention, the photocatalyst layer may contain conductive particles. The conductive particles may be those that allow the photolysis reaction of water to occur efficiently. For example, as described in JP-A-2017-124393, a photocatalyst particle in which conductive particles are connected between a visible light responsive photocatalyst particle for hydrogen generation and a visible light responsive photocatalyst particle for oxygen generation. The conductive particles are at a position more negative than the electron energy level at the upper end of the valence band of the visible light responsive photocatalyst particles for hydrogen generation, and the electrons at the lower end of the conduction band of the visible light responsive photocatalyst particles for oxygen generation. It is a conductive particle that has a Fermi level at a position more positive than the energy level and can store electrons and holes. By using such conductive particles, photoexcited holes generated in the visible light responsive photocatalyst particles for hydrogen generation and photoexcited electrons generated in the visible light responsive photocatalyst particles for oxygen generation by the charge recombination reaction can be generated. It is considered that it can be extinguished and the efficiency of the reduction reaction of water by the photoexcited electrons generated in the conduction band of the visible light responsive photocatalytic particles for hydrogen generation can be increased. As a result, the photocatalytic efficiency of water and the ability to generate hydrogen by the photocatalytic material can be improved.
導電性粒子の好ましい材料の例として、金、銀、銅、ニッケル、ロジウム、パラジウム等の金属、カーボン材料、ＴｉＮ等の窒化物、ＴｉＣ等の炭化物、スズドープ酸化インジウム（ＩＴＯ）、金属（Ｂ，Ａｌ，Ｇａ）ドープ酸化亜鉛、フッ素ドープ酸化スズ、アンチモンドープ酸化スズ、酸化ルテニウム、酸化イリジウム、酸化ロジウム等の導電性の金属酸化物からなる群から選択される１種以上のものが挙げられる。これらの中でも、金、カーボン材料、ＩＴＯ、および金属（Ｂ，Ａｌ，Ｇａ）ドープ酸化亜鉛、酸化ルテニウム、酸化イリジウム等の導電性の金属酸化物からなる群から選択される１種以上のものがより好ましい。 Examples of preferable materials for conductive particles include metals such as gold, silver, copper, nickel, rhodium and palladium, carbon materials, nitrides such as TiN, carbides such as TiC, tin-doped indium oxide (ITO) and metals (B, Al, Ga) Examples thereof include one or more selected from the group consisting of conductive metal oxides such as doped zinc oxide, fluorine-doped tin oxide, antimony-doped tin oxide, ruthenium oxide, iridium oxide and rhodium oxide. Among these, one or more selected from the group consisting of gold, carbon materials, ITO, and conductive metal oxides such as metal (B, Al, Ga) -doped zinc oxide, ruthenium oxide, and iridium oxide. More preferred.
本発明において、導電性粒子が親水性バインダーを兼用してもよい。つまり、導電性粒子および光触媒粒子の材料がいずれも金属酸化物である場合、光触媒粒子と導電性粒子とは金属酸化物同士であるため、導電性粒子は優れたバインダー効果を得ることができ、導電性粒子と光触媒粒子との接触をより強固なものとすることができる。また、基板の材料としてガラス、アルミナ等の無機物、特に金属酸化物を用い、導電性粒子の材料も金属酸化物である場合、基板と導電性粒子との間で金属−酸素結合が形成される。そのため、導電性粒子と基板との密着性が向上する。その結果、光触媒材全体の機械的強度を向上させることが可能となる。よって、光触媒材が水素製造モジュールに搭載された場合において、光触媒層は、流水による負荷による光触媒粒子の脱離を抑制することができ、長期耐久性に優れた光触媒膜として機能することが可能となる。 In the present invention, the conductive particles may also serve as a hydrophilic binder. That is, when the materials of the conductive particles and the photocatalyst particles are both metal oxides, the photocatalyst particles and the conductive particles are metal oxides, so that the conductive particles can obtain an excellent binder effect. The contact between the conductive particles and the photocatalyst particles can be strengthened. Further, when an inorganic substance such as glass or alumina, particularly a metal oxide, is used as the material of the substrate and the material of the conductive particles is also a metal oxide, a metal-oxygen bond is formed between the substrate and the conductive particles. .. Therefore, the adhesion between the conductive particles and the substrate is improved. As a result, it is possible to improve the mechanical strength of the entire photocatalyst material. Therefore, when the photocatalyst material is mounted on the hydrogen production module, the photocatalyst layer can suppress the detachment of the photocatalyst particles due to the load due to running water, and can function as a photocatalyst film having excellent long-term durability. Become.
導電性粒子はいかなる形状であってもよく、例えば、粒状あるいは被膜状であってよい。ここで、導電性粒子が被膜状であるとは、光触媒粒子表面上に、明確な粒界を有する粒子としてではなく、無定形の連続的な被膜として導電性材料が担持されている状態を表す。ただし、光触媒全面を導電性粒子被膜が覆うと、光触媒活性表面が失われてしまうことから、導電性粒子に被覆されていない光触媒表面も有することが重要である。導電性粒子が被膜状の場合、その厚さは１ｎｍ以上１００ｎｍ以下であることが好ましい。厚さは、たとえば、被膜表面を透過型電子顕微鏡観察にて観察した際の１０点の平均値として求めることができる。導電性粒子が粒状の場合、その平均一次粒子径は１ｎｍ以上１０μｍ以下であることが好ましい。平均一次粒子径は、例えば、粒状物または被膜状物を、走査型電子顕微鏡（例えば、ＳＵ−８２２０、日立ハイテク製）を用いて、倍率２００００倍、２００ｎｍ角の視野で二次電子像を観察した際の結晶粒子１０個の円形近似による平均値として求めることができる。 The conductive particles may have any shape, for example, granular or film-like. Here, the fact that the conductive particles are in the form of a film means that the conductive material is supported on the surface of the photocatalyst particles not as particles having a clear grain boundary but as an amorphous continuous film. .. However, if the entire surface of the photocatalyst is covered with the conductive particle coating, the photocatalyst active surface is lost. Therefore, it is important to have a photocatalyst surface that is not coated with the conductive particles. When the conductive particles are in the form of a film, the thickness thereof is preferably 1 nm or more and 100 nm or less. The thickness can be determined, for example, as an average value of 10 points when the surface of the coating film is observed by a transmission electron microscope. When the conductive particles are granular, the average primary particle diameter is preferably 1 nm or more and 10 μm or less. For the average primary particle size, for example, a granular or film-like material is observed with a scanning electron microscope (for example, SU-8220, manufactured by Hitachi High-Tech) at a magnification of 20000 times and a secondary electron image in a field of view of 200 nm square. It can be obtained as an average value by circular approximation of 10 crystal particles.
光触媒層中に含まれる固形分全体に対する導電性粒子の含有割合は、１ｗｔ％以上９９ｗｔ％以下であることが好ましく、導電性粒子の種類、形態などに応じて適宜決定すればよい。例えば、導電性粒子としてＩＴＯを用いる場合、その含有割合は２ｗｔ％〜８０ｗｔ％であることが好ましい。 The content ratio of the conductive particles to the total solid content contained in the photocatalyst layer is preferably 1 wt% or more and 99 wt% or less, and may be appropriately determined according to the type and form of the conductive particles. For example, when ITO is used as the conductive particles, the content ratio thereof is preferably 2 wt% to 80 wt%.
中間層
本発明において、光触媒材１００は、基板２と光触媒層１との間に中間層をさらに含んでもよい。中間層は、基板２と光触媒層１との間に配置され、基板２及び光触媒層１のそれぞれと接続される。これによって、例えば、基板２と光触媒層１との間の密着性を向上させることができる。中間層は基板と同様に絶縁性である。中間層に用いられる材料としては、基板が樹脂基板である場合、シランカップリング剤、チタネートカップリング剤、リン酸カップリング剤等が挙げられる。
Intermediate layer In the present invention, the photocatalyst material 100 may further include an intermediate layer between the substrate 2 and the photocatalyst layer 1. The intermediate layer is arranged between the substrate 2 and the photocatalyst layer 1 and is connected to each of the substrate 2 and the photocatalyst layer 1. Thereby, for example, the adhesion between the substrate 2 and the photocatalyst layer 1 can be improved. The intermediate layer is insulating like the substrate. When the substrate is a resin substrate, examples of the material used for the intermediate layer include a silane coupling agent, a titanate coupling agent, and a phosphoric acid coupling agent.
基板
本発明による光触媒材に含まれる基板２は、その表面に光触媒層１を固定化し得る絶縁性基板であればよい。このような基板２の具体例としては、硬質の有機基板または無機基板が挙げられる。有機基板には、例えば、プラスチック基板が挙げられる。無機基板には、例えば、アルミナ基板などのセラミックス基板、ソーダライムガラス、ホウケイ酸ガラスなどのガラス基板、石英基板が挙げられる。基板２は、電気抵抗率が１０５Ω・ｃｍ以上であるものが好ましい。
Substrate The substrate 2 included in the photocatalyst material according to the present invention may be an insulating substrate capable of immobilizing the photocatalyst layer 1 on its surface. Specific examples of such a substrate 2 include a hard organic substrate or an inorganic substrate. Examples of the organic substrate include a plastic substrate. Examples of the inorganic substrate include a ceramic substrate such as an alumina substrate, a glass substrate such as soda lime glass and borosilicate glass, and a quartz substrate. Substrate 2, the electrical resistivity is what is preferably 10 5 Ω · cm or more.
絶縁性基板であることで、多種多様な部材を安価で用いることができる。さらには、例えば導電性基板で課題となる酸化還元反応あるいは水中での耐久性や酸化劣化の課題も低減できるため、耐久性のある光触媒材を得ることができる。 Since it is an insulating substrate, a wide variety of members can be used at low cost. Further, for example, the redox reaction, which is a problem in a conductive substrate, or the problem of durability and oxidative deterioration in water can be reduced, so that a durable photocatalyst material can be obtained.
基板２は、その表面に乾燥または焼成によって光触媒層１が固定化され得る形状を有するものであればよい。このような基板２の具体例としては、平滑表面を有する平板体（例えばガラス基板、アルミナ基板等）、あるいは表面多孔性の平板体（例えば陽極酸化アルミナ）、多孔体（例えばポーラスセラミックス）、繊維体（例えばガラスファイバー、炭素繊維）等を用いることができる。基板２の表面は、荒らされた粗面であることが好ましい。粗面であることにより、光触媒層１と基板２との密着性が向上する。粗度は、ＩＳＯ ２５１７８に準拠して求められる算術平均高さＳａが光触媒層表面のＳａよりも小さいことが好ましい。例えば、基板２の表面形状は、波打った形状、くし型の形状、繊維状、メッシュ状であってよい。また、基板２の大きさ、厚みは、その表面に光触媒層１が固定化可能である限り特に制限されない。 The substrate 2 may have a shape such that the photocatalyst layer 1 can be immobilized on the surface thereof by drying or firing. Specific examples of such a substrate 2 include a flat plate having a smooth surface (for example, a glass substrate, an alumina substrate, etc.), a flat plate having a porous surface (for example, anodized alumina), a porous body (for example, porous ceramics), and fibers. A body (for example, glass fiber, carbon fiber) or the like can be used. The surface of the substrate 2 is preferably a roughened rough surface. The rough surface improves the adhesion between the photocatalyst layer 1 and the substrate 2. As for the roughness, it is preferable that the arithmetic mean height Sa obtained in accordance with ISO 25178 is smaller than the Sa on the surface of the photocatalyst layer. For example, the surface shape of the substrate 2 may be a wavy shape, a comb shape, a fibrous shape, or a mesh shape. Further, the size and thickness of the substrate 2 are not particularly limited as long as the photocatalyst layer 1 can be immobilized on the surface thereof.
本発明において、基板２は、複数の凹部および凸部を含む凹凸形状を有し、光触媒層１における凸部と凹部との高低差Ｄ１が、基板２における凸部と凹部との高低差Ｄ２よりも大きいことが好ましい。このような形状的特徴により、光触媒層の表面における水素ガス及び／又は酸素ガスの気泡の成長を抑制し、水素ガス及び／又は酸素ガスを光触媒層の表面から速やかに離脱させることが可能となるとともに、水分解により一旦発生した水素および酸素が反応して再び水を生成する逆反応を防止することが可能となる。基板２における凸部と凹部との高低差Ｄ２は、０μｍを超え９０μｍ以下であることが好ましい。 In the present invention, the substrate 2 has a concave-convex shape including a plurality of concave portions and convex portions, and the height difference D 1 between the convex portion and the concave portion in the photocatalyst layer 1 is the height difference D between the convex portion and the concave portion in the substrate 2. It is preferably larger than 2 . Due to such a shape feature, it is possible to suppress the growth of bubbles of hydrogen gas and / or oxygen gas on the surface of the photocatalyst layer, and to quickly separate the hydrogen gas and / or oxygen gas from the surface of the photocatalyst layer. At the same time, it is possible to prevent a reverse reaction in which hydrogen and oxygen once generated by water decomposition react to generate water again. The height difference D 2 between the convex portion and the concave portion on the substrate 2 is preferably more than 0 μm and 90 μm or less.
基板２における凸部と凹部との高低差Ｄ２は、先に述べた光触媒層１における凸部と凹部との高低差Ｄ１と同様、例えば以下のように測定される。 The height difference D 2 between the convex portion and the concave portion on the substrate 2 is measured as follows, for example, similarly to the height difference D 1 between the convex portion and the concave portion in the photocatalyst layer 1 described above.
レーザー顕微鏡に所定倍率の光学レンズを装着し、所定の視野にて基板を観察し、基板表面の三次元画像を得る。得られた画像において、任意に選択した複数の凸部の各頂点又は頂上部までの高さを測定し、それらの平均値を求める。また、得られた画像において、任意に選択した複数の凹部の各底点又は底部までの高さを測定し、それらの平均値を求める。複数の凸部の各頂点又は頂上部までの高さの平均値から、複数の凹部の各底点又は底部までの高さの平均値を引いて、所定角の視野での基板における凸部と凹部との高低差を求める。 An optical lens having a predetermined magnification is attached to a laser microscope, the substrate is observed in a predetermined field of view, and a three-dimensional image of the surface of the substrate is obtained. In the obtained image, the height to each apex or apex of a plurality of arbitrarily selected convex portions is measured, and the average value thereof is obtained. Further, in the obtained image, the heights to the bottom points or the bottoms of a plurality of arbitrarily selected recesses are measured, and the average value thereof is obtained. The average value of the heights to the vertices or tops of the plurality of convex portions is subtracted from the average value of the heights to the bottom points or bottoms of the plurality of concave portions to obtain the convex portions on the substrate in the field of view at a predetermined angle. Find the height difference from the recess.
あるいは、走査型電子顕微鏡による観察でも基板２における凸部と凹部との高低差Ｄ２の高低差を測定することができる。例えば、光触媒材の破断面の走査型電子顕微鏡（例えば、ＳＵ−８２２０、日立ハイテク製）における二次電子像による断面観察により、倍率５００倍の視野で観察した際の膜断面における凸部と凹部の高低差を測定する。
上記の視野とは異なる視野５点の観察を行い、各視野での基板における凸部と凹部との高低差を求める。異なる視野での基板における凸部と凹部との高低差の平均値を、基板における凸部と凹部との高低差とする。
Alternatively, the height difference of the height difference D 2 between the convex portion and the concave portion on the substrate 2 can be measured by observation with a scanning electron microscope. For example, by observing the fracture surface of the photocatalyst material with a secondary electron image using a scanning electron microscope (for example, SU-8220, manufactured by Hitachi High-Tech), the protrusions and recesses in the film cross section when observed in a field of view at a magnification of 500 times. Measure the height difference of.
Five visual fields different from the above visual fields are observed, and the height difference between the convex portion and the concave portion on the substrate in each visual field is obtained. The average value of the height difference between the convex portion and the concave portion on the substrate in different fields of view is defined as the height difference between the convex portion and the concave portion on the substrate.
光触媒材の製造方法
本発明による光触媒材の製造方法としては、先ず、基板に、光触媒粒子と、親水性バインダーと、分散媒とを含む組成物を適用する。次いで、基板上に適用された前記組成物を乾燥し、組成物に有機物からなる増粘剤、結着剤、または造孔剤を含む場合は、さらに焼成して、光触媒層を形成する。
As a method for producing a photocatalyst material according to the production method the present invention photocatalyst material, first, a substrate, applying the photocatalyst particles, a hydrophilic binder, a composition comprising a dispersion medium. The composition applied onto the substrate is then dried, and if the composition contains an organic thickener, binder, or pore-forming agent, it is further fired to form a photocatalytic layer.
本発明において、光触媒粒子と親水性バインダーを分散媒中で分散させる方法として、光触媒粒子と親水性バインダーのそれぞれの粒子の表面に、水や有機溶媒などの溶媒あるいは分散剤を吸着させる方法を使用することができる。これにより、各粒子が一次粒子に近い形態で、安定に混合された状態を実現することが可能となる。つまり、光触媒粒子同士、あるいは親水性バインダー同士の凝集を抑制することができる。従って、光触媒層においては、例えば、光触媒粒子が親水性バインダーを介して近い距離で存在できる。そのため、水分解反応が促進され、水素の発生効率を高めることができる。分散方法としては、超音波照射、ボールミルおよびビーズミル等の機械分散法を用いることができる。なお、分散工程に際し、親水性バインダーの代わりに、その前駆体、具体的には、Ｓｉ、Ｔｉ、Ｚｒ、Ｔａ、Ｎｂ、Ｆｅ、Ｓｎ等の金属を含む酸化物、水酸化物または複合酸化物を形成可能な前駆体を用いてもよい。金属の代わりに、金属の塩を用いてもよい。 In the present invention, as a method of dispersing the photocatalyst particles and the hydrophilic binder in the dispersion medium, a method of adsorbing a solvent such as water or an organic solvent or a dispersant on the surface of each particle of the photocatalyst particles and the hydrophilic binder is used. can do. As a result, it is possible to realize a state in which each particle is stably mixed in a form close to that of the primary particle. That is, it is possible to suppress the aggregation of the photocatalytic particles or the hydrophilic binders. Therefore, in the photocatalyst layer, for example, the photocatalyst particles can exist at a short distance via the hydrophilic binder. Therefore, the water splitting reaction is promoted, and the hydrogen generation efficiency can be increased. As the dispersion method, a mechanical dispersion method such as ultrasonic irradiation, a ball mill and a bead mill can be used. In the dispersion step, instead of the hydrophilic binder, a precursor thereof, specifically, an oxide containing a metal such as Si, Ti, Zr, Ta, Nb, Fe, Sn, a hydroxide or a composite oxide A precursor capable of forming the above may be used. A metal salt may be used instead of the metal.
本発明において、分散媒としては、光触媒粒子と親水性バインダーを分散することが可能な溶媒を用いることができる。本発明の好ましい態様によれば、このような溶媒として、水あるいは有機溶媒を用いることができる。有機溶媒は乾燥し易いため水より好ましく、例えば、α―テルピネオールやブチルカルビトール等を用いることができる。 In the present invention, as the dispersion medium, a solvent capable of dispersing the photocatalytic particles and the hydrophilic binder can be used. According to a preferred embodiment of the present invention, water or an organic solvent can be used as such a solvent. The organic solvent is preferable to water because it dries easily, and for example, α-terpineol, butyl carbitol, and the like can be used.
本発明において、組成物には、添加剤として、分散剤、増粘剤、ｐＨ調整剤、または造孔剤を使用してもよい。造孔剤は、基材に適用された分散液を乾燥させ、その後焼成する際に、光触媒層から消失するような成分であることが好ましく、具体的には有機物であることが好ましい。これにより、得られる光触媒層を多孔質化することができる。造孔剤として、より好ましくは、ポリビニルブチラール、エチルセルロース、ポリアクリル系樹脂などのポリマーを用いることができる。 In the present invention, a dispersant, a thickener, a pH adjuster, or a pore-forming agent may be used as an additive in the composition. The pore-forming agent is preferably a component that disappears from the photocatalyst layer when the dispersion liquid applied to the base material is dried and then fired, and specifically, it is preferably an organic substance. Thereby, the obtained photocatalyst layer can be made porous. More preferably, a polymer such as polyvinyl butyral, ethyl cellulose, or a polyacrylic resin can be used as the pore-forming agent.
本発明にあっては、光触媒粒子と親水性バインダーとが分散された分散液を基板に適用する際に、光触媒層の表面に凹凸形状を形成するための作業が行われる。本発明において、分散液を基板へ適用する方法としては、スクリーン印刷法、樹脂型または金型を用いた転写法が好ましく利用される。スクリーン印刷法においては、光触媒層の表面に目的の凹凸形状を形成可能な形状を有するスクリーンメッシュ等を用いて、基板に分散液をスクリーン印刷することにより、光触媒層の表面に目的の凹凸形状を形成する。転写法においては、光触媒層の表面に目的の凹凸形状を形成可能な形状を有する樹脂型または金型を用いて、基板に分散液を転写することにより、光触媒層の表面に目的の凹凸形状を形成する。 In the present invention, when a dispersion liquid in which photocatalyst particles and a hydrophilic binder are dispersed is applied to a substrate, an operation for forming an uneven shape on the surface of the photocatalyst layer is performed. In the present invention, a screen printing method, a resin mold, or a transfer method using a mold is preferably used as a method for applying the dispersion liquid to the substrate. In the screen printing method, the desired uneven shape is formed on the surface of the photocatalyst layer by screen-printing the dispersion liquid on the substrate using a screen mesh or the like having a shape capable of forming the desired uneven shape on the surface of the photocatalyst layer. Form. In the transfer method, the desired uneven shape is formed on the surface of the photocatalyst layer by transferring the dispersion liquid to the substrate using a resin mold or a mold having a shape capable of forming the desired uneven shape on the surface of the photocatalyst layer. Form.
上記方法で凹凸形状を形成するために、組成物は適当な粘弾特性を有することが好ましく、ペースト状であることがより好ましい。 In order to form the uneven shape by the above method, the composition preferably has appropriate viscous properties, and more preferably paste-like.
本発明において、基板を前処理してもよい。前処理として、洗剤・研磨剤による洗浄、ブラストや化学処理による粗面化が挙げられる。また、光触媒層を後処理してもよい。後処理として、凹凸形状が形成された光触媒層に対して、エッチングによる多孔質化を行ってもよい。 In the present invention, the substrate may be pretreated. Pretreatment includes cleaning with detergent / abrasive and roughening by blasting or chemical treatment. Moreover, you may post-treat the photocatalyst layer. As a post-treatment, the photocatalyst layer having the uneven shape may be made porous by etching.
水分解用光触媒モジュール
本発明による水分解用光触媒モジュールは、上述の光触媒材を含む。本発明の好ましい態様によれば、本発明による水分解用光触媒モジュールは、概ね透明な光入射面を有し、モジュール内部に設置した光触媒材に光が入射する構造を有する。光源として、太陽光、ＬＥＤ、キセノンランプ、水銀灯を用いることができる。光入射面は、ガラスや透明樹脂製の窓であってもよい。また、本発明による水分解用光触媒モジュールは、光触媒材が常に水と接触可能なように、水を封入可能な密閉パネル形状を有している。また、本発明のより好ましい態様によれば、本発明による水分解用光触媒モジュールは、水分解反応の進行により減少する水を遂次的に追加供給可能な通水孔（水流入口、水流出口）等の機構をさらに有することが好ましい。例えば、水流出口は、発生した水素ガス及び／又は酸素ガスを分離するための手段に連結する孔として作用してもよい。このような構成の水分解光触媒モジュールとすることで、実用的に利用可能な水素を製造することが可能となる。
Photocatalyst module for water decomposition The photocatalyst module for water decomposition according to the present invention includes the above-mentioned photocatalyst material. According to a preferred embodiment of the present invention, the photocatalyst module for water splitting according to the present invention has a generally transparent photocatalytic surface and has a structure in which light is incident on a photocatalyst material installed inside the module. As a light source, sunlight, an LED, a xenon lamp, or a mercury lamp can be used. The light incident surface may be a window made of glass or a transparent resin. Further, the photocatalyst module for water decomposition according to the present invention has a closed panel shape in which water can be sealed so that the photocatalyst material can always come into contact with water. Further, according to a more preferable aspect of the present invention, the photocatalyst module for water splitting according to the present invention has water passage holes (water inlet, water outlet) capable of sequentially additionally supplying water which is reduced due to the progress of the water splitting reaction. It is preferable to further have a mechanism such as. For example, the water outlet may act as a hole connecting to a means for separating the generated hydrogen gas and / or oxygen gas. By using a water splitting photocatalyst module having such a configuration, it becomes possible to produce hydrogen that can be practically used.
水素製造システム
本発明による水素製造システムは、前記水分解用光触媒モジュールを含む。本発明の好ましい態様によれば、本発明による水素製造システムは、水の供給装置、水中の不純物をある程度除去するためのろ過装置、水分解光触媒モジュール、水素分離装置、および水素貯蔵装置からなるものである。水素分離装置は、爆発を抑制するため、酸素含有量を低下させる機能を有し、ゼオライト、炭素、またはシリカ等のガス分離膜を備える。このような構成の水素製造システムとすることで、再生可能エネルギーである太陽光と水から水素を実用的に製造可能なシステムを実現することが可能となる。
Hydrogen production system The hydrogen production system according to the present invention includes the photocatalyst module for water splitting. According to a preferred embodiment of the present invention, the hydrogen production system according to the present invention comprises a water supply device, a filtration device for removing impurities in water to some extent, a water splitting photocatalyst module, a hydrogen separation device, and a hydrogen storage device. Is. The hydrogen separation device has a function of lowering the oxygen content in order to suppress an explosion, and includes a gas separation membrane such as zeolite, carbon, or silica. By adopting a hydrogen production system having such a configuration, it is possible to realize a system capable of practically producing hydrogen from renewable energies such as sunlight and water.
以下の実施例によって本発明をさらに詳細に説明する。なお、本発明はこれらの実施例に限定されるものではない。 The present invention will be described in more detail by the following examples. The present invention is not limited to these examples.
実施例１
１−１．光触媒粒子の調製
１−１−１ ＡｌドープＳｒＴｉＯ ３ （ＳＴＯＡ）の合成
ＳｒＣｌ２（１５．８ｇ）、ＳｒＴｉＯ３（１．８ｇ）、Ａｌ２Ｏ３（２０．４ｍｇ）の混合粉末をメノウ乳鉢に入れ、１５分間すり潰し混合した。この粉末をるつぼに移し、電気炉で焼成した（昇温時間１１５分間、温度１１５０℃、１０ 時間焼成）。
焼成後のるつぼを室温まで放冷し、生成物とフラックス（ＳｒＣｌ２）の混合物である残留物を超純水で洗浄することでフラックスを溶解除去した後、乾燥機で乾燥（８０℃、終夜乾燥）させることで、ＳＴＯＡを得た。
Example 1
1-1. Preparation of photocatalytic particles
1-1-1 Synthesis of Al-doped SrTiO 3 (STOA) SrCl 2 (15.8 g), SrTiO 3 (1.8 g), Al 2 O 3 (20.4 mg) mixed powder was placed in an agate mortar for 15 minutes. Grinded and mixed. This powder was transferred to a crucible and fired in an electric furnace (heating time 115 minutes, temperature 1150 ° C., 10 hours firing).
The crucible after firing is allowed to cool to room temperature, and the residue, which is a mixture of the product and flux (SrCl 2 ), is washed with ultrapure water to dissolve and remove the flux, and then dried in a dryer (80 ° C, overnight). STOA was obtained by drying).
１−１−２ ＳＴＯＡ粒子へのＲｈＣｒＯ ｘ 助触媒の担持
１−１−１で得られたＳＴＯＡ（和光）をメノウ乳鉢ですり潰してから、蒸発皿に０．３ｇを入れて蒸留水（０．５ｍｌ）を加えて懸濁させた。一方、Ｎａ３［ＲｈＣｌ６］・ｎＨ２Ｏ（９．８ｍｇ）、Ｃｒ（ＮＯ３）６・９Ｈ２Ｏ（１１．５ｍｇ）を蒸留水（０．５ｍｌ）にそれぞれ溶かし、Ｒｈイオン含有溶液、Ｃｒイオン含有溶液を作製した。Ｒｈイオン含有溶液０．１ｍｌ、Ｃｒイオン含有溶液０．１ｍｌをＳＴＯＡ懸濁液に加えた。
次に、１００℃に加熱したホットプレート上に、上記懸濁液の入った蒸発皿をのせ、溶媒が蒸発するまで分散溶液を撹拌しながら加熱した。得られた粉末を磁性るつぼに移し、電気炉で焼成し、ＲｈＣｒＯｘ／ＳＴＯＡ粒子を得た（昇温時間３５分間、温度３５０℃、１ 時間焼成）。
1-1-2 Supporting RhCrO x cocatalyst on STOA particles The STOA (Wako) obtained in 1-1-1 was ground in an agate mortar, and then 0.3 g was added to an evaporating dish and distilled water (0. 5 ml) was added and suspended. On the other hand, dissolved Na 3 [RhCl 6] · nH 2 O (9.8mg), respectively Cr (NO 3) 6 · 9H 2 O (11.5mg) and distilled water (0.5 ml), Rh ion-containing solution, A Cr ion-containing solution was prepared. 0.1 ml of Rh ion-containing solution and 0.1 ml of Cr ion-containing solution were added to the STOA suspension.
Next, an evaporating dish containing the above suspension was placed on a hot plate heated to 100 ° C., and the dispersion solution was heated with stirring until the solvent evaporated. The obtained powder was transferred to a magnetic crucible and fired in an electric furnace to obtain RhCrO x / STOA particles (heating time 35 minutes, temperature 350 ° C., 1 hour firing).
１−２．光触媒材の作製
１−２−１ スクリーン印刷用ペースト（組成物）の作製
１−１−２で得られたＲｈＣｒＯｘ／ＳＴＯＡ粒子５ｇおよびイソプロピルアルコール分散シリカ粒子（日産化学製、“ＩＰＡ−ＳＴ−ＵＰ”）６．７ｇ（固形分１ｇ）および有機ビヒクル（綜研化学製、“ＳＰＢ−１”、アクリル樹脂＋α‐テルピネオール）４ｇを混合し、イソプロピルアルコールを蒸発留去することで印刷用ペーストを作製した。
1-2. Fabrication of photocatalytic material
1-2-1 Preparation of Screen Printing Paste (Composition) 5 g of RhCrO x / STOA particles and isopropyl alcohol-dispersed silica particles (manufactured by Nissan Chemical Co., Ltd., “IPA-ST-UP”) 6 obtained in 1-1-2. A printing paste was prepared by mixing 7 g (solid content 1 g) and 4 g of an organic vehicle (manufactured by Soken Kagaku Co., Ltd., “SPB-1”, acrylic resin + α-terpineol) and evaporating and distilling off isopropyl alcohol.
１−２−２ スクリーン印刷
１−２−１で得られたペーストを、ホウケイ酸ガラス基板（３０×３０×０．５５ｍｍ角）に、メッシュスクリーン（＃８０メッシュ：メッシュ線径８０μｍ、紗厚２２５μｍ、）を用いてスクリーン印刷により製膜（製膜面積２５ｍｍ角）し、１００℃で３０分乾燥後、３５０℃で４時間焼成することで、断面が山型の凹凸形状である光触媒層を作製し、実施例１の光触媒材を得た。
1-2-2 Screen printing The paste obtained in 1-2-1 is applied to a borosilicate glass substrate (30 x 30 x 0.55 mm square) on a mesh screen (# 80 mesh: mesh wire diameter 80 μm, gauze thickness 225 μm). ,) Is screen-printed (film-forming area 25 mm square), dried at 100 ° C. for 30 minutes, and then fired at 350 ° C. for 4 hours to produce a photocatalyst layer having a mountain-shaped uneven cross section. Then, the photocatalyst material of Example 1 was obtained.
実施例２
メッシュスクリーンを＃３２５メッシュ：メッシュ線径２８μｍ、紗厚７７μｍ、に変更した以外は実施例１と同様に作製して、実施例２の光触媒材を得た。
Example 2
A photocatalyst material of Example 2 was obtained by producing the same as in Example 1 except that the mesh screen was changed to # 325 mesh: mesh wire diameter 28 μm and gauze thickness 77 μm.
実施例３
スクリーン印刷の工程を以下の条件としたこと以外は実施例１と同様に作製して実施例３の光触媒材を得た。
１−２−１で得られたペーストを、ホウケイ酸ガラス基板（３０×３０×０．５５ｍｍ角）にメッシュスクリーン（＃３２５メッシュ：メッシュ線径２８μｍ、紗厚７７μｍ）を用いてスクリーン印刷により製膜（製膜面積２５ｍｍ角）し、１００℃で３０分乾燥させた。この膜上に、ドット型メッシュスクリーン（孔径３００μｍ、厚さ８５μｍ）でドットパターンを製膜した。最後に、３５０℃で４時間焼成することで、実施例３の光触媒材を作製した。
Example 3
A photocatalyst material of Example 3 was obtained by producing in the same manner as in Example 1 except that the screen printing step was set to the following conditions.
The paste obtained in 1-2-1 is produced by screen printing on a borosilicate glass substrate (30 × 30 × 0.55 mm square) using a mesh screen (# 325 mesh: mesh wire diameter 28 μm, gauze thickness 77 μm). A film (film-forming area 25 mm square) was formed and dried at 100 ° C. for 30 minutes. A dot pattern was formed on this film with a dot-type mesh screen (pore diameter 300 μm, thickness 85 μm). Finally, the photocatalyst material of Example 3 was prepared by firing at 350 ° C. for 4 hours.
実施例４
ドット型メッシュスクリーンを、孔径１０００μｍ、厚さ８５μｍのものに変えた以外は実施例３と同様に作製して、実施例４の光触媒材を得た。
Example 4
The dot-type mesh screen was produced in the same manner as in Example 3 except that the hole diameter was changed to 1000 μm and the thickness was 85 μm to obtain the photocatalyst material of Example 4.
実施例５
５−１．光触媒粒子の作製
５−１−１ 第１の光触媒粒子（3%RhドープSrTiO 3 粒子）の作製
3%RhドープSrTiO3(SrTi0.97Rh0.03O3)粒子を固相法により作製した。具体的には、SrCO3（和光純薬製，99.9%）、TiO2（高純度化学研究所製，99.99%）、およびRh2O3（和光純薬製）を1.05：0.97：0.03のモル比でアルミナ製乳鉢に入れ、メタノールを添加した後、２時間混合した。次いで、得られた混合物をアルミナ製るつぼに入れて、９００℃で１時間仮焼きした後、１０５０℃で１０時間本焼成した。焼成後、焼成体を室温まで放冷させた後、解砕して、3%RhドープSrTiO3(SrTi0.97Rh0.03O3)粒子からなる粉末を作製した。
Example 5
5-1. Preparation of photocatalytic particles
5-1-1 Preparation of first photocatalytic particles (3% Rh-doped SrTiO 3 particles)
3% Rh-doped SrTiO 3 (SrTi 0.97 Rh 0.03 O 3 ) particles were prepared by the solid phase method. Specifically, SrCO 3 (manufactured by Wako Pure Chemical Industries, 99.9%), TiO 2 (manufactured by High Purity Chemical Laboratory, 99.99%), and Rh 2 O 3 (manufactured by Wako Pure Chemical Industries, Ltd.) in a molar ratio of 1.05: 0.97: 0.03 The mixture was placed in an alumina mortar at a ratio, methanol was added, and the mixture was mixed for 2 hours. Next, the obtained mixture was placed in an alumina crucible and calcined at 900 ° C. for 1 hour, and then fired at 1050 ° C. for 10 hours. After firing, the fired body was allowed to cool to room temperature and then crushed to prepare a powder composed of 3% Rh-doped SrTiO 3 (SrTi 0.97 Rh 0.03 O 3 ) particles.
SEM観察により3%RhドープSrTiO3粒子（第１の光触媒粒子）の平均一次粒子径を算出した。具体的には、SEM（株式会社日立製作所製、“Ｓ−４１００”）により、倍率４００００倍で観察した際の結晶粒子５０個の円形近似による平均値を一次粒子径とした。その結果、3%RhドープSrTiO3粒子の平均一次粒子径は約500nmであった。
3%RhドープSrTiO3粒子のバンド位置は、Wang et al., J.Catal. 305-315, 328 (2015)を参照して以下のとおりとみなした。
価電子帯上端：-6.6eV (vs.真空準位)
伝導帯下端：-4.1eV (vs.真空準位)
なお、3%RhドープSrTiO3粒子における価電子帯上端とは、SrTiO3のバンドギャップ内に生じた、ドープされたRh3+由来のドナー軌道の上端に由来するものであると考えられる。
The average primary particle size of 3% Rh-doped SrTiO 3 particles (first photocatalytic particles) was calculated by SEM observation. Specifically, the primary particle diameter was defined as the average value obtained by circular approximation of 50 crystal particles when observed by SEM (manufactured by Hitachi, Ltd., “S-4100”) at a magnification of 40,000 times. As a result, the average primary particle size of the 3% Rh-doped SrTiO 3 particles was about 500 nm.
The band positions of the 3% Rh-doped SrTiO 3 particles were considered as follows with reference to Wang et al., J. Catal. 305-315, 328 (2015).
Upper end of valence band: -6.6eV (vs. Vacuum level)
Lower end of conduction band: -4.1eV (vs. Vacuum level)
The upper end of the valence band in the 3% Rh-doped SrTiO 3 particle is considered to be derived from the upper end of the donor orbit derived from the doped Rh 3+ generated in the band gap of SrTiO3.
５−１−２ 第２の光触媒粒子（CoOx担持BiVO 4 粒子）の作製
CoOxが担持されたBiVO4粒子を液固相法により作製した。具体的には、まず、K2CO3（関東化学製，99.5％）およびV2O5（和光純薬製，99.0％）をK：V=3.03：5 (mol比)になるようにメノウ乳鉢に入れ、エタノール(10mL)を添加した後30分間混合した。次いで、得られた混合物を磁性るつぼに入れて、電気炉にて大気中450℃で5時間焼成した。焼成後、焼成体を室温まで放冷させた後、解砕した。
5-1-2 Preparation of second photocatalytic particles (CoOx-supported BiVO 4 particles)
BiVO 4 particles carrying CoO x were prepared by the liquid solid phase method. Specifically, first, agate with K 2 CO 3 (manufactured by Kanto Chemical Co., Inc., 99.5%) and V 2 O 5 (manufactured by Wako Junyaku, 99.0%) so that K: V = 3.03: 5 (mol ratio). Placed in a mortar, ethanol (10 mL) was added and mixed for 30 minutes. The resulting mixture was then placed in a magnetic crucible and fired in an electric furnace at 450 ° C. for 5 hours. After firing, the fired body was allowed to cool to room temperature and then crushed.
得られた粉末を、100mlの水およびBi(NO3)3・5H2O（和光，99.9％）が入った300mL三角フラスコに入れて（Bi : V=1 :1）、70℃で10時間、攪拌子を用いて1500 rpmで撹拌した。得られた沈殿物を吸引濾過により回収して水洗浄を行った後、乾燥器にて60℃で12時間乾燥させて、BiVO4粉末を得た。 The resulting powder, 100 ml of water and Bi (NO 3) 3 · 5H 2 O ( Wako, 99.9%) was placed in the entered was 300mL Erlenmeyer flasks (Bi: V = 1: 1 ), 10 hours at 70 ° C. , Stirred at 1500 rpm using a stirrer. The obtained precipitate was collected by suction filtration, washed with water, and dried in a dryer at 60 ° C. for 12 hours to obtain BiVO 4 powder.
得られたBiVO4粉末0.5gを磁性るつぼに入れ、助触媒の原料としてCoOが0.5wt%になるように、Co(NO3)2（和光，99.5％）を磁性るつぼに入れ、純水を少量加えた。超音波でBiVO4粉末を十分に懸濁した後、湯浴で蒸発乾燥させた。最後に、電気炉にて大気中３００℃で２時間焼成した。これにより、酸素発生用助触媒としてCoOxが担持されたBiVO4粉末を作製した。 Put 0.5 g of the obtained BiVO 4 powder in a magnetic crucible, put Co (NO 3 ) 2 (Wako, 99.5%) in a magnetic crucible so that CoO becomes 0.5 wt% as a raw material for the cocatalyst, and add pure water. A small amount was added. The BiVO 4 powder was sufficiently suspended by ultrasonic waves, and then evaporated and dried in a hot water bath. Finally, it was fired in an electric furnace at 300 ° C. for 2 hours. As a result, a BiVO 4 powder carrying CoO x as an oxygen evolution co-catalyst was prepared.
SEM観察によりCoOxが担持されたBiVO4粒子（第２の光触媒粒子）の平均一次粒子径を算出した。その結果、平均一次粒子径は約500nmであった。
BiVO4のバンド位置は、Wang et al., J.Catal. 305-315, 328 (2015)を参照して以下のとおりとみなした。
価電子帯上端：-6.8eV(vs.真空準位)
伝導帯下端：-4.6eV(vs.真空準位)
By SEM observation, the average primary particle size of BiVO 4 particles (second photocatalytic particles) carrying CoO x was calculated. As a result, the average primary particle size was about 500 nm.
The band positions of BiVO 4 were considered as follows with reference to Wang et al., J. Catal. 305-315, 328 (2015).
Upper end of valence band: -6.8eV (vs. vacuum level)
Lower end of conduction band: -4.6eV (vs. Vacuum level)
５−２．光触媒材の作製
５−２−１ スクリーン印刷用ペースト（組成物）の作製
５−１−１で得られた第１の光触媒粒子と、５−１−２で得られた第２の光触媒粒子とを、１：１の割合で合計量が０．２ｇとなるように秤量した。これと、２−プロパノール分散ＩＴＯ粒子スラリー（ＩＴＯ組成：Ｉｎ１．８Ｓｎ０．２Ｏ３、ＩＴＯ一次粒子径：約２０ｎｍ）０．２５ｇ（固形分０．０５ｇ）と、有機分散媒０．７５ｇとを混合し、２−プロパノールを蒸発留去することで印刷用ペーストを作製した。なお、有機分散媒としては、α−テルピネオール（関東化学製）と、２−（２−ブトキシエトキシ）エタノール（和光純薬製）と、ポリアクリル樹脂（SPB-TE1、綜研化学製）とが、この順に重量比で、６２．５：１２．５：２５．０の割合で混合されたものを用いた。
5-2. Fabrication of photocatalytic material
Preparation of 5-2-1 Screen Printing Paste (Composition) The first photocatalytic particles obtained in 5-1-1 and the second photocatalyst particles obtained in 5-1-2 were combined with 1: Weighed at a ratio of 1 so that the total amount was 0.2 g. This, 2-propanol-dispersed ITO particle slurry (ITO composition: In 1.8 Sn 0.2 O 3 , ITO primary particle size: about 20 nm) 0.25 g (solid content 0.05 g), and an organic dispersion medium 0. A printing paste was prepared by mixing with 75 g and evaporating and distilling off 2-propanol. As the organic dispersion medium, α-terpineol (manufactured by Kanto Chemical Co., Inc.), 2- (2-butoxyethoxy) ethanol (manufactured by Wako Pure Chemical Industries, Ltd.), and polyacrylic resin (SPB-TE1, manufactured by Soken Chemical Co., Ltd.) are used. Those mixed in this order in a weight ratio of 62.5: 12.5: 25.0 were used.
５−２−２ スクリーン印刷
５−２−１で得られたペーストを、ホウケイ酸ガラス基板（３０×３０×０．５５ｍｍ角）に、メッシュスクリーン（＃８０メッシュ：メッシュ線径８０μｍ、紗厚２２５μｍ、）を用いてスクリーン印刷により製膜（製膜面積２５ｍｍ角）し、１００℃で３０分乾燥後、３５０℃で４時間焼成することで、断面が山形の凹凸形状である光触媒層を作製し、実施例５の光触媒材を得た。
5-2-2 Screen printing The paste obtained in 5-2-1 is applied to a borosilicate glass substrate (30 x 30 x 0.55 mm square) on a mesh screen (# 80 mesh: mesh wire diameter 80 μm, gauze thickness 225 μm). ,) Is screen-printed (film-forming area 25 mm square), dried at 100 ° C. for 30 minutes, and then fired at 350 ° C. for 4 hours to prepare a photocatalyst layer having a chevron-shaped uneven cross section. , The photocatalytic material of Example 5 was obtained.
実施例６
メッシュスクリーンを＃３２５メッシュ：メッシュ線径２８μｍ、紗厚７７μｍ、に変更した以外は実施例５と同様に作製して、実施例６の光触媒材を得た。
Example 6
A photocatalyst material of Example 6 was obtained by producing the same as in Example 5 except that the mesh screen was changed to # 325 mesh: mesh wire diameter 28 μm and gauze thickness 77 μm.
実施例７
スクリーン印刷の工程を以下の条件としたこと以外は実施例５と同様に作製して実施例７の光触媒材を得た。
５−２−１で得られたペーストを、ホウケイ酸ガラス基板（３０×３０×０．５５ｍｍ角）にメッシュスクリーン（＃３２５メッシュ：メッシュ線径２８μｍ、紗厚７７μｍ）を用いてスクリーン印刷により製膜（製膜面積２５ｍｍ角）し、１００℃で３０分乾燥させた。この膜上に、ドット型メッシュスクリーン（孔径３００μｍ、厚さ８５μｍ）でドットパターンを製膜した。最後に、３５０℃で４時間焼成することで、実施例７の光触媒材を作製した。
Example 7
A photocatalyst material of Example 7 was obtained by producing in the same manner as in Example 5 except that the screen printing step was set to the following conditions.
The paste obtained in 5-2-1 is produced by screen printing on a borosilicate glass substrate (30 × 30 × 0.55 mm square) using a mesh screen (# 325 mesh: mesh wire diameter 28 μm, gauze thickness 77 μm). A film (film-forming area 25 mm square) was formed and dried at 100 ° C. for 30 minutes. A dot pattern was formed on this film with a dot-type mesh screen (pore diameter 300 μm, thickness 85 μm). Finally, the photocatalyst material of Example 7 was prepared by firing at 350 ° C. for 4 hours.
比較例１
実施例１のスクリーン印刷の工程を、以下の条件としたこと以外は実施例１と同様に作製して比較例１の光触媒材を得た。
ホウケイ酸ガラス基板（３０×３０×０．５５ｍｍ角）に、メタルフレーム（３０ｍｍ×３０ｍｍ×２２５μｍのシートに２５ｍｍ角の開口を設けたもの）を置き、開口部に１−２−１で得られたペーストを適量のせ、メタルスキージで余分なペーストを除去した後、メタルフレームを除去した。これにより得られた製膜体を、１００℃で３０分乾燥後、３５０℃で４時間焼成することで、表面が平滑な光触媒層を備える比較例１の光触媒材を得た。
Comparative Example 1
The screen printing step of Example 1 was produced in the same manner as in Example 1 except that the following conditions were met, and a photocatalytic material of Comparative Example 1 was obtained.
A metal frame (a sheet of 30 mm x 30 mm x 225 μm with a 25 mm square opening) was placed on a borosilicate glass substrate (30 x 30 x 0.55 mm square), and the opening was obtained in 1-2-1. An appropriate amount of the paste was applied, excess paste was removed with a metal squeegee, and then the metal frame was removed. The film-formed body thus obtained was dried at 100 ° C. for 30 minutes and then fired at 350 ° C. for 4 hours to obtain a photocatalyst material of Comparative Example 1 having a photocatalyst layer having a smooth surface.
比較例２
実施例５のスクリーン印刷の工程を、比較例１に記載の条件としたこと以外は実施例５と同様に作製して、表面が平滑な光触媒層を備える比較例２の光触媒材を得た。
Comparative Example 2
The screen printing step of Example 5 was produced in the same manner as in Example 5 except that the conditions described in Comparative Example 1 were used to obtain a photocatalyst material of Comparative Example 2 having a photocatalyst layer having a smooth surface.
評価
１．光触媒層における凸部と凹部との高低差の測定
得られた光触媒材において、光触媒層における凸部と凹部との高低差を測定した。具体的には、レーザー顕微鏡（オリンパス製、ＯＬＳ２０００）に倍率１０倍の光学レンズを装着して、光触媒層（２．５ｃｍ角）における約１．３ｍｍ角の視野の観察を行い、光触媒層表面の三次元画像を得た。得られた画像において、任意に選択した５つの凸部の各頂点又は頂上部までの高さ（Ｈ１１Ｓ）を測定し、それらの平均値（Ｈ１１Ｓ０）を求めた。また、得られた画像において、任意に選択した５つの凹部の各底点又は底部までの高さ（Ｈ１２Ｂ）を測定し、それらの平均値（Ｈ１２Ｂ０）を求めた。Ｈ１１Ｓ０−Ｈ１２Ｂ０により、約１．３ｍｍ角の視野での光触媒層における凸部と凹部との高低差を求めた。
上記の視野とは異なる視野でさらに４つの観察を行い、各視野での光触媒層における凸部と凹部との高低差を求めた。合計５つの異なる視野での光触媒層における凸部と凹部との高低差の平均値を、光触媒層における凸部と凹部との高低差とした。
Evaluation
1. 1. Measurement of Height Difference between Convex and Concave in the Photocatalyst Layer In the obtained photocatalyst material, the height difference between the convex and concave portion in the photocatalyst layer was measured. Specifically, an optical lens having a magnification of 10 times is attached to a laser microscope (OLS2000 manufactured by Olympus) to observe a field of view of about 1.3 mm square in the photocatalyst layer (2.5 cm square), and the surface of the photocatalyst layer is observed. A three-dimensional image was obtained. In the obtained image, the height (H 11S ) to each apex or apex of the five arbitrarily selected convex portions was measured, and the average value (H 11S0 ) of them was obtained. Further, in the obtained image, the height (H 12B ) to the bottom point or the bottom of each of the five arbitrarily selected recesses was measured, and the average value (H 12B0 ) of them was determined. The height difference between the convex portion and the concave portion in the photocatalyst layer in a field of view of about 1.3 mm square was determined by H 11S0 −H 12B0 .
Four more observations were made in a field of view different from the above field of view, and the height difference between the convex portion and the concave portion in the photocatalyst layer in each visual field was determined. The average value of the height difference between the convex portion and the concave portion in the photocatalyst layer in a total of five different visual fields was defined as the height difference between the convex portion and the concave portion in the photocatalyst layer.
なお、得られた各光触媒材において、使用したホウケイ酸ガラス基板の表面は平滑である、すなわち、基板が光触媒層に対して平面とみなせるため、評価１．で求められた光触媒層における凸部の高さの平均値（Ｈ１１Ｓ０）を、光触媒層における凸部の厚さの平均値とみなした。同様に、評価１．で求められた光触媒層における凹部の高さの平均値（Ｈ１２Ｂ０）を、光触媒層における凹部の厚さの平均値とみなした。 In each of the obtained photocatalyst materials, the surface of the borosilicate glass substrate used was smooth, that is, the substrate could be regarded as a flat surface with respect to the photocatalyst layer. The average value (H 11S0 ) of the height of the convex portion in the photocatalyst layer obtained in 1 ) was regarded as the average value of the thickness of the convex portion in the photocatalyst layer. Similarly, evaluation 1. The average value of the heights of the recesses in the photocatalyst layer (H 12B0 ) obtained in 1 ) was regarded as the average value of the thicknesses of the recesses in the photocatalyst layer.
２．光触媒層における凸部のピッチの測定
評価１．で得られた三次元画像において、任意に選択した５つの凸部の各頂点又は頂上部の間のピッチの平均値を求め、約１．３ｍｍ角の視野での光触媒層における凸部のピッチとした。
上記の視野とは異なる視野でさらに４つの観察を行い、各視野での光触媒層における凸部のピッチを求めた。合計５つの異なる視野での光触媒層における凸部のピッチの平均値を、光触媒層における凸部のピッチとした。
2. 2. Measurement and evaluation of the pitch of the convex part in the photocatalyst layer 1. In the three-dimensional image obtained in the above, the average value of the pitches between the vertices or the apex of the five arbitrarily selected convex parts was obtained, and the pitch of the convex parts in the photocatalyst layer in a field of view of about 1.3 mm square was obtained. did.
Four more observations were made in a field of view different from the above field of view, and the pitch of the convex portion in the photocatalyst layer in each field of view was determined. The average value of the pitches of the convex portions in the photocatalyst layer in a total of five different fields of view was taken as the pitch of the convex portions in the photocatalyst layer.
３．光触媒層の表面の算術平均高さ（Ｓａ）の測定
評価１．で得られた三次元画像を用い、ＩＳＯ ２５１７８に準拠して、約１．３ｍｍ角の視野での光触媒層の表面の算術平均高さ（Ｓａ）を求めた。
上記の視野とは異なる視野でさらに４つの観察を行い、各視野での光触媒層の表面の算術平均高さ（Ｓａ）を求めた。合計５つの異なる視野での光触媒層の表面の算術平均高さ（Ｓａ）の平均値を、光触媒層の表面の算術平均高さ（Ｓａ）とした。
3. 3. Measurement and evaluation of the arithmetic mean height (Sa) on the surface of the photocatalyst layer 1. The arithmetic mean height (Sa) of the surface of the photocatalyst layer in a field of view of about 1.3 mm square was determined according to ISO 25178 using the three-dimensional image obtained in.
Four more observations were made in a field of view different from the above field of view, and the arithmetic mean height (Sa) of the surface of the photocatalyst layer in each field of view was determined. The average value of the arithmetic mean height (Sa) of the surface of the photocatalyst layer in a total of five different fields of view was taken as the arithmetic mean height (Sa) of the surface of the photocatalyst layer.
４．光触媒活性の測定
ホウケイ酸ガラス製上方照射用の窓付きのガラスフラスコに、光触媒材と、超純水１００ｍｌを入れて、反応溶液とした。この反応溶液を入れたガラスフラスコを閉鎖循環装置（幕張理化学製）に装着し、反応系内の雰囲気をアルゴン置換した（アルゴン圧：１０ｋＰａ）。アルミニウム製全反射板を装着した３００Ｗキセノンランプ（Ｃｅｒｍａｘ製、ＰＥ−３００ＢＦ）により、紫外および可視光をフラスコのホウケイ酸ガラス上部窓側から照射した。光照射した後５時間の、水が還元されて生成する水素の発生量および水が酸化されて生成する酸素の発生量を、ガスクロマトグラフ（島津製作所製、ＧＣ−８Ａ、ＴＣＤ検出器、ＭＳ−５Ａカラム）により経時的に調べた。
4. Measurement of photocatalytic activity A photocatalytic material and 100 ml of ultrapure water were placed in a glass flask made of borosilicate glass with a window for upward irradiation to prepare a reaction solution. A glass flask containing this reaction solution was mounted on a closed circulation device (manufactured by Makuhari Rikagaku), and the atmosphere in the reaction system was replaced with argon (argon pressure: 10 kPa). Ultraviolet and visible light was irradiated from the upper window side of the borosilicate glass of the flask by a 300 W xenon lamp (Cermax, PE-300BF) equipped with a total reflection plate made of aluminum. Gas chromatograph (manufactured by Shimadzu Corporation, GC-8A, TCD detector, MS-) shows the amount of hydrogen generated by reducing water and the amount of oxygen generated by oxidizing water for 5 hours after light irradiation. It was examined over time by a 5A column).
５．気泡の大きさの測定
光触媒材の表面から生成する気泡のサイズを以下の方法で測定した。レーザー顕微鏡（オリンパス製、ＯＬＳ２０００）に倍率１０倍の光学レンズを装着して、上記の光触媒活性評価において膜表面から連続的に生成する気泡に焦点を当てた条件で、光触媒層（２．５ｃｍ角）における約１．３ｍｍ角の視野の観察を行った。間欠撮影した観察写真５点における、膜表面から連続的に生成する気泡のサイズを測定し、観察された気泡サイズの平均値を算出した。
5. Measurement of bubble size The size of bubbles generated from the surface of the photocatalytic material was measured by the following method. A photocatalyst layer (2.5 cm square) under the condition that an optical lens with a magnification of 10 times is attached to a laser microscope (OLS2000 manufactured by Olympus) and the bubbles continuously generated from the film surface are focused in the above photocatalyst activity evaluation. ), The field of view of about 1.3 mm square was observed. The size of bubbles continuously generated from the film surface was measured at five observation photographs taken intermittently, and the average value of the observed bubble sizes was calculated.
結果
評価１〜４の結果は、表１に示されるとおりであった。
同一の基材および同一組成の光触媒層を備える、実施例１の光触媒材と比較例１の光触媒材を対比することにより、光触媒層の表面形状を、平滑形状から凹凸形状に変えるだけで、２倍程度の水素発生活性が得られることが確認された。
The results of result evaluations 1 to 4 were as shown in Table 1.
By comparing the photocatalyst material of Example 1 and the photocatalyst material of Comparative Example 1 having the same base material and the photocatalyst layer having the same composition, the surface shape of the photocatalyst layer is simply changed from a smooth shape to an uneven shape. It was confirmed that about twice the hydrogen generation activity was obtained.
実施例１および比較例１について、評価５の気泡の大きさを測定した。結果は、実施例１での気泡サイズは、平均５０μｍであり、比較例１の気泡サイズは、平均８００μｍであった。 For Example 1 and Comparative Example 1, the size of the bubbles in Evaluation 5 was measured. As a result, the bubble size in Example 1 was 50 μm on average, and the bubble size in Comparative Example 1 was 800 μm on average.
１００ 光触媒材
１ 光触媒層
１１ 凸部
１１Ｓ 凸部の頂点又は頂上部
１２ 凹部
１２Ｂ 凹部の底点又は底部
２ 絶縁性の基板
３ 光触媒粒子
４ 親水性バインダー
５ 水
６ 細孔
Ｔ１１ 凸部１１の厚さ
Ｔ１２ 凹部１２の厚さ
Ｄ１ 光触媒層における凸部と凹部との高低差
Ｄ２ 基板２における凸部と凹部との高低差
100 Photocatalyst material 1 Photocatalyst layer 11 Convex 11S Top or top of convex 12 Recess 12B Bottom or bottom of recess 2 Insulating substrate 3 Photocatalyst particles 4 Hydrophilic binder 5 Water 6 Pore T 11 Thickness of convex 11 T 12 Thickness of the concave portion 12 D 1 Height difference between the convex portion and the concave portion in the photocatalyst layer D 2 Height difference between the convex portion and the concave portion on the substrate 2
Claims (11)
前記光触媒層が、水の光分解反応を触媒する光触媒粒子と、親水性バインダーとを含んでなる多孔質な層であり、かつ、複数の凹部および凸部を含む凹凸形状を有してなり、
前記光触媒層において、前記凸部と前記凹部との高低差が５μｍ以上１００μｍ以下であり、かつ、前記凸部の厚さが前記凹部の厚さよりも大である
ことを特徴とする、光触媒材。 A photocatalyst material comprising an insulating substrate and a photocatalyst layer formed on the substrate.
The photocatalyst layer is a porous layer containing photocatalyst particles for catalyzing the photocatalytic reaction of water and a hydrophilic binder, and has an uneven shape including a plurality of concave portions and convex portions.
In the photocatalyst layer, the photocatalyst material is characterized in that the height difference between the convex portion and the concave portion is 5 μm or more and 100 μm or less, and the thickness of the convex portion is larger than the thickness of the concave portion.
前記光触媒層における凸部と凹部との高低差が、前記基板における凸部と凹部との高低差より大である、請求項１〜３のいずれか一項に記載の光触媒材。 The substrate has a concavo-convex shape including a plurality of concave portions and convex portions.
The photocatalyst material according to any one of claims 1 to 3, wherein the height difference between the convex portion and the concave portion in the photocatalyst layer is larger than the height difference between the convex portion and the concave portion in the substrate.
前記光触媒層が、水を光分解して水素ガス及び／又は酸素ガスを生成する反応を触媒する光触媒粒子と、親水性バインダーとを含んでなる多孔質な層であり、
前記光触媒層が、複数の凹部および凸部を含む凹凸形状を有してなり、
前記光触媒材が水と接したときに、前記光触媒層が前記凹凸形状を有することに起因して、前記水素ガス、前記酸素ガス、または前記水素ガスと前記酸素ガスとが混合されたものが、直径１００μｍ以下の気泡として、前記光触媒層の前記凹凸形状の表面から放出されることを特徴とする、光触媒材。 A photocatalyst material comprising an insulating substrate and a photocatalyst layer formed on the substrate.
The photocatalyst layer is a porous layer containing photocatalyst particles for catalyzing a reaction of photodecomposing water to generate hydrogen gas and / or oxygen gas, and a hydrophilic binder.
The photocatalyst layer has an uneven shape including a plurality of concave portions and convex portions.
When the photocatalyst material comes into contact with water, the hydrogen gas, the oxygen gas, or a mixture of the hydrogen gas and the oxygen gas is produced because the photocatalyst layer has the uneven shape. A photocatalyst material, which is emitted from the uneven surface of the photocatalyst layer as bubbles having a diameter of 100 μm or less.
絶縁性の基板上に、水を光分解して水素ガス及び／又は酸素ガスを生成する反応を触媒する光触媒粒子と、親水性バインダーと、分散媒とを含む組成物を適用する工程と、
前記基板上に適用された前記組成物を乾燥および焼成して光触媒層を形成する工程と
を少なくとも含んでなり、
前記光触媒層が、複数の凹部および凸部を含む凹凸形状を有してなり、
前記光触媒層における前記凸部と前記凹部との高低差が、５μｍ以上１００μｍ以下であり、
前記複数の凸部の各厚さの平均値が、前記複数の凹部の各厚さの平均値よりも大である
ことを特徴とする方法。 The method for producing a photocatalytic material according to any one of claims 1 to 6.
A step of applying a composition containing a photocatalytic particle, a hydrophilic binder, and a dispersion medium that catalyzes a reaction of photolyzing water to generate hydrogen gas and / or oxygen gas on an insulating substrate.
It comprises at least a step of drying and firing the composition applied on the substrate to form a photocatalyst layer.
The photocatalyst layer has an uneven shape including a plurality of concave portions and convex portions.
The height difference between the convex portion and the concave portion in the photocatalyst layer is 5 μm or more and 100 μm or less.
A method characterized in that the average value of each thickness of the plurality of convex portions is larger than the average value of each thickness of the plurality of concave portions.
The method according to claim 10, wherein the arithmetic mean height (Sa) of the substrate is smaller than the arithmetic mean height of the surface of the photocatalyst layer.
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|---|---|---|---|---|
| WO2022123644A1 (en) * | 2020-12-08 | 2022-06-16 | 日本電信電話株式会社 | Semiconductor photoelectrode and method for producing semiconductor photoelectrode |
| CN115337946A (en) * | 2021-05-15 | 2022-11-15 | 陕西青朗万城环保科技有限公司 | Process and device for manufacturing porous ceramic microwave catalyst |
| CN115869935A (en) * | 2021-09-30 | 2023-03-31 | 丰田自动车株式会社 | Semiconductor particles for water-splitting photocatalyst, photocatalyst formed of semiconductor particles, and synthesis method thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000279905A (en) * | 1998-02-06 | 2000-10-10 | Toto Ltd | Method of cleaning composite material and self-cleaning composite mechanism |
| JP2012011362A (en) * | 2010-07-05 | 2012-01-19 | Ngk Insulators Ltd | Composite-type photocatalyst |
| WO2014046305A1 (en) * | 2012-09-21 | 2014-03-27 | Toto株式会社 | Composite photocatalyst, and photocatalyst material |
| JP2016215159A (en) * | 2015-05-22 | 2016-12-22 | 日本電信電話株式会社 | Semiconductor photocatalytic film and oxide-reduction reactor |
| JP2017124393A (en) * | 2015-07-31 | 2017-07-20 | Toto株式会社 | Photocatalytic material and manufacturing method therefor |
-
2019
- 2019-02-28 JP JP2019035519A patent/JP7202527B2/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000279905A (en) * | 1998-02-06 | 2000-10-10 | Toto Ltd | Method of cleaning composite material and self-cleaning composite mechanism |
| JP2012011362A (en) * | 2010-07-05 | 2012-01-19 | Ngk Insulators Ltd | Composite-type photocatalyst |
| WO2014046305A1 (en) * | 2012-09-21 | 2014-03-27 | Toto株式会社 | Composite photocatalyst, and photocatalyst material |
| JP2016215159A (en) * | 2015-05-22 | 2016-12-22 | 日本電信電話株式会社 | Semiconductor photocatalytic film and oxide-reduction reactor |
| JP2017124393A (en) * | 2015-07-31 | 2017-07-20 | Toto株式会社 | Photocatalytic material and manufacturing method therefor |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022123644A1 (en) * | 2020-12-08 | 2022-06-16 | 日本電信電話株式会社 | Semiconductor photoelectrode and method for producing semiconductor photoelectrode |
| CN115337946A (en) * | 2021-05-15 | 2022-11-15 | 陕西青朗万城环保科技有限公司 | Process and device for manufacturing porous ceramic microwave catalyst |
| CN115869935A (en) * | 2021-09-30 | 2023-03-31 | 丰田自动车株式会社 | Semiconductor particles for water-splitting photocatalyst, photocatalyst formed of semiconductor particles, and synthesis method thereof |
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