JP2005199222A - Visible light active sulfide solid solution photocatalyst improved in activity efficiency and activity stability and producing hydrogen by optical decomposition of water and its manufacturing method - Google Patents
Visible light active sulfide solid solution photocatalyst improved in activity efficiency and activity stability and producing hydrogen by optical decomposition of water and its manufacturing method Download PDFInfo
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- YGANSGVIUGARFR-UHFFFAOYSA-N dipotassium dioxosilane oxo(oxoalumanyloxy)alumane oxygen(2-) Chemical compound [O--].[K+].[K+].O=[Si]=O.O=[Al]O[Al]=O YGANSGVIUGARFR-UHFFFAOYSA-N 0.000 description 1
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- 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
Abstract
Description
本発明は、活性特性及び活性安定性を改善した可視光活性硫化物固溶体系からなる光水分解触媒系及びその製造方法に関する。 The present invention relates to a photohydrolysis catalyst system comprising a visible light activated sulfide solid solution system with improved activity characteristics and activity stability, and a method for producing the same.
化石資源は無尽蔵とは言えないことから、これらを化学原料に振り向けることが資源の有効利用の観点から好ましい。また、地球温暖化などの環境問題などの観点から、ＣＯ２の発生を伴わないクリーンなエネルギーへの変換が熱望されている。また、石炭の燃焼の際にはＣＯ２の発生だけでなく、白雲母として石炭中に含まれている化合物からのフッ素の発生も有ると言われている。前記問題ないエネルギー供給手段として登場して来た原子力利用の発電技術も、燃料物質を製造する工程、及び使用後の処理において生成する物質の兵器としての使用などによる世界秩序の破壊が懸念されるという事態に至り、大きな問題を抱えることになった。このような中で、環境に優しく、安全性が高く、かつ設備コストも比較的かからないエネルギー資源の開発が望まれている。最近、風力発電に、無尽蔵なエネルギー資源の利用の観点、及び設備費も比較的小さいなどから、多くの投資が向けられている。また、太陽電池もクリーンで、利用性の高いエネルギーを生産することから、実用化され、かつ更に効率性の向上と、安定したエネルギー供給に向けて多数の研究が行われている。また、太陽光を利用するエネルギー変換技術として、光触媒を利用した水の光分解反応に興味が持たれている。ここで利用される水の光分解反応に活性を示す光触媒は、光吸収、電荷分離、表面での酸化還元反応といった機能を備えた高度な光機能材料であり、多くのものが提案されている。 Since fossil resources cannot be said to be inexhaustible, it is preferable to allocate them to chemical raw materials from the viewpoint of effective use of resources. In addition, from the viewpoint of environmental problems such as global warming, conversion to clean energy without generating CO 2 is eagerly desired. Further, it is said that not only the generation of CO 2 but also the generation of fluorine from a compound contained in the coal as muscovite when the coal is burned. The nuclear power generation technology that has emerged as a non-problematic energy supply means is also concerned about the destruction of the world order due to the use of substances produced in the process of manufacturing fuel materials and the processing after use as weapons. This led to a big problem. Under such circumstances, development of energy resources that are environmentally friendly, high in safety, and relatively low in equipment costs is desired. Recently, many investments have been directed to wind power generation because of its infinite use of energy resources and relatively low equipment costs. In addition, since solar cells produce clean and highly usable energy, they have been put into practical use, and many studies have been conducted for further improving efficiency and supplying stable energy. In addition, as an energy conversion technology using sunlight, there is an interest in water photolysis using a photocatalyst. The photocatalyst active in the photolysis reaction of water used here is an advanced photofunctional material having functions such as light absorption, charge separation, and surface oxidation-reduction reaction, and many have been proposed. .
前記太陽光エネルギーを有効利用して水を分解し水素を得る新しいエネルギーシステムの構築には、太陽光のほぼ９５％以上が可視光およびそれより長波長側領域であることの観点から、可視光応答性光触媒の開発が強く望まれている。しかしながら可視光照射下で水の分解に高効率な光触媒は未だ見出されていない。犠牲試薬存在下においては可視光を利用可能な２．４ｅＶのバンドギャップを持つＣｄＳが白金を担持することで、可視光照射下での水素生成反応に高活性を示す光触媒を構成できることがこれまでに報告されている（非特許文献１、２）。ＺｎＳは紫外光照射下ではあるがＰｔのような助触媒を担持しなくても水素生成反応に高活性を示す光触媒であることが知られている（非特許文献３、４）。このような中で、本発明者らのグループでは、これまでに金属イオンをドーピングしたＺｎＳ光触媒やＺｎＳ光触媒とＡｇＩｎＳ２またはＣｕＩｎＳ２との固溶体が可視光照射下で水素生成反応に高い活性を示すことに関して多くの報告をしている（非特許文献５−１０）。また、前記研究の中で、ＺｎＳにＡｇＩｎＳ２とＣｕＩｎＳ２を共に固溶することで、より長波長領域の可視光の利用が可能になることも報告した（非特許文献１１）。更に、他の硫化物光触媒として、ＺｎＳ類似のカルコパイラト型構造をもつＡｇＧａＳ２、層状構造のＮａＩｎＳ２も可視光照射下において犠牲試薬存在下で水素生成に高活性を示すことを報告してきた（非特許文献１２、１３）。しかし、これらの硫化物光触媒は、水素生成反応に高い活性を示すものの光触媒反応過程において徐々に失活してしまうという欠点がある。また、利用できる波長領域も満足できるものではない。 For the construction of a new energy system that effectively utilizes the solar energy to decompose water and obtain hydrogen, visible light is used from the viewpoint that almost 95% or more of sunlight is in the visible light and longer wavelength side region. Development of a responsive photocatalyst is strongly desired. However, a highly efficient photocatalyst for the decomposition of water under visible light irradiation has not yet been found. In the presence of a sacrificial reagent, CdS having a band gap of 2.4 eV that can use visible light supports platinum, so that a photocatalyst exhibiting high activity in the hydrogen generation reaction under visible light irradiation can be constructed so far. (Non-Patent Documents 1 and 2). ZnS is known to be a photocatalyst exhibiting high activity in the hydrogen generation reaction even when it does not carry a promoter such as Pt under ultraviolet light irradiation (Non-patent Documents 3 and 4). Under these circumstances, in our group, ZnS photocatalyst doped with metal ions or a solid solution of ZnS photocatalyst and AgInS 2 or CuInS 2 shows high activity in hydrogen generation reaction under visible light irradiation. Many reports have been made on this matter (Non-patent Documents 5-10). Further, the in studies, that together solid solution AgInS 2 and CuInS 2 to ZnS, also reported that it allows the use of visible light having a longer wavelength region (Non-Patent Document 11). Further, as another sulfide photocatalyst, AgGaS 2 with Karukopairato structure of ZnS similar to NaInS 2 layered structures have reported to exhibit high activity in hydrogen generation in the presence of a sacrificial reagent under visible light irradiation (non Patent Documents 12 and 13). However, although these sulfide photocatalysts exhibit high activity in the hydrogen generation reaction, there is a drawback that they are gradually deactivated during the photocatalytic reaction process. Also, the usable wavelength region is not satisfactory.
本発明の課題は、基本的には、より長波長の可視光で水分解活性を有し、更に前記光水分解活性の劣化を改善した組成（ＣｕＡｇ）ＸＩｎ２ＸＺｎ２（１−２Ｘ）Ｓ２（ここで、Ｘは０．１５±０．０２）で表される固溶体を提供することである。更に、前記光水分解活性を向上させた触媒を提供することである。前記基本特性の改善が如何にしたら実現できるか、最も基本に戻り前記固溶体の製造条件を見出すべく多くの製造条件を試行錯誤の実験を試みた。その中で、前記固溶体の製造工程における熱処理条件として、比較的低い温度と処理時間を長時間とすることにより、また、硫黄雰囲気中で熱処理することで、表面積を維持したまま結晶性のよい粒子が合成でき、Ｐｔ助触媒を用いた場合においても光水分解活性に改善が見られ、更に、助触媒としてＲｕを担持させることにより前記水素生成反応の活性が顕著に向上させることができることを発見し、前記課題を解決することができた。 The subject of the present invention is basically a composition (CuAg) X In 2X Zn 2 (1-2X) having water decomposition activity with visible light having a longer wavelength and further improving the degradation of the photowater decomposition activity. This is to provide a solid solution represented by S 2 (where X is 0.15 ± 0.02). Furthermore, it is providing the catalyst which improved the said photo-water decomposition activity. In order to find out how the improvement of the basic characteristics can be realized, the most basic conditions were tried and trial and error experiments were conducted to find out the manufacturing conditions of the solid solution. Among them, as a heat treatment condition in the manufacturing process of the solid solution, the particles having good crystallinity while maintaining the surface area by making the temperature relatively low and the treatment time long, and also by heat treatment in a sulfur atmosphere. It was discovered that even when Pt cocatalyst was used, the photohydrolysis activity was improved, and further, the activity of the hydrogen generation reaction could be significantly improved by supporting Ru as a cocatalyst. And the said subject was able to be solved.
本発明第１は、（１）温度８００℃±１５０℃の範囲及び処理時間３以上３７時間以下の範囲の組み合わせ条件の熱処理行程を含む合成条件で得られる（ＣｕＡｇ）ＸＩｎ２ＸＺｎ２（１−２Ｘ）Ｓ２（ここで、Ｘは０．１５±０．０２）の組成、ＢＥＴ等温吸着法の比表面積が０．９〜３．６ｍ２／ｇ、及びバンドギャップ２．０±０．１ｅＶの特性を有し、硫黄化合物を含む水溶液の光水分解により水素を生成する活性を有する硫化物固溶体からなる光触媒である。好ましくは、（２）熱処理を硫黄雰囲気中実施する前記（１）に記載の硫化物固溶体からなる光触媒であり、より好ましくは、（３）熱処理前に硫黄を焼成前の前駆体に対し１０±２重量％を添加する前記（２）に記載の硫化物固溶体からなる光触媒である。また、好ましくは、（４）熱処理の処理時間が昇温時間２．０以上１５時間以下の昇温時間を含み、全焼成時間が３時間以上３７時間以下の範囲である前記（１）、（２）または（３）に記載の硫化物固溶体からなる光触媒であり、より好ましくは、（５）Ｒｕ、Ｐｔ、ＲｈまたはＩｒ助触媒を担持させた前記（１）、（２）、（３）または（４）に記載の硫化物固溶体からなる光触媒であり、一層好ましくは、（６）（ＣｕＡｇ）ＸＩｎ２ＸＺｎ２（１−２Ｘ）Ｓ２固溶体及びＲｕ、Ｐｔ、ＲｈまたはＩｒの塩化物を硫化物固溶体光触媒水素生成光分解溶液に添加される少なくともＳＯ３ ２−イオンが存在する水溶液に添加し、前記硫化物固溶体光触媒水素生成反応を進行させる光照射による光電着により前記固溶体に助触媒を担持させた前記（５）に記載の光触媒である。また、好ましくは、（７）硫黄化合物を含む水溶液がＳＯ３ ２−とＳ２−イオンが存在する水溶液である前記（１）乃至（６）の１つである光触媒である。 The present invention first is (1) obtained in Synthesis conditions including heat treatment step of conditions the combination of range and treatment time 3 to 37 hours or less in the range of temperature of 800 ℃ ± 150 ℃ (CuAg) X In 2X Zn 2 (1-2X) S 2 (where X is 0.15 ± 0.02), the specific surface area of the BET isothermal adsorption method is 0.9 to 3.6 m 2 / g, and the band gap is 2.0 ±. It is a photocatalyst composed of a sulfide solid solution having a characteristic of 0.1 eV and having an activity of generating hydrogen by photohydrolysis of an aqueous solution containing a sulfur compound. Preferably, (2) the photocatalyst comprising the sulfide solid solution according to the above (1), wherein the heat treatment is performed in a sulfur atmosphere, and more preferably (3) 10 ±± of the sulfur before the heat treatment with respect to the precursor before firing. A photocatalyst comprising the sulfide solid solution according to (2), wherein 2% by weight is added. Preferably, (4) the heat treatment time includes a temperature rising time of 2.0 to 15 hours, and the total baking time is in the range of 3 to 37 hours (1), ( 2) or a photocatalyst comprising the sulfide solid solution according to (3), more preferably (5) the above (1), (2), (3) carrying Ru, Pt, Rh or Ir promoter Or a photocatalyst comprising the sulfide solid solution according to (4), more preferably (6) (CuAg) X In 2X Zn 2 (1-2X) S 2 solid solution and a chloride of Ru, Pt, Rh or Ir Is added to the aqueous solution containing at least SO 3 2- ion added to the sulfide solid solution photocatalyst hydrogen generation photodecomposition solution, and the solid solution is co-catalyzed by photo-irradiation by light irradiation to advance the sulfide solid solution photocatalyst hydrogen generation reaction. Carrying It was a photocatalyst according to (5). Preferably, (7) the photocatalyst is one of the above (1) to (6), wherein the aqueous solution containing a sulfur compound is an aqueous solution in which SO 3 2− and S 2− ions are present.
本発明の第２は、（８）（ＣｕＡｇ）ＸＩｎ２ＸＺｎ２（１−２Ｘ）Ｓ２（ここで、Ｘは０．１５±０．０２）を温度８００℃±１５０℃の範囲及び処理時間３以上３７時間以下の範囲の組み合わせた処理条件で熱処理し、ＢＥＴ等温吸着法の比表面積が０．９ｍ２／ｇ以上３．６ｍ２／ｇ以上、及びバンドギャップ２．０±０．１ｅＶの特性を有し、硫黄化合物を含む水溶液の光水分解により水素を生成する活性を有する（ＣｕＡｇ）ＸＩｎ２ＸＺｎ２（１−２Ｘ）Ｓ２（ここで、Ｘは０．１５±０．０２）の組成の硫化物固溶体からなる光触媒を製造する方法である。好ましくは、（９）（ＣｕＡｇ）ＸＩｎ２ＸＺｎ２（１−２Ｘ）Ｓ２固溶体及びＲｕ、Ｐｔ、ＲｈまたはＩｒの塩化物を硫化物固溶体光触媒水素生成光分解溶液に添加される少なくともＳＯ３ ２−イオンが存在する水溶液に添加し、前記硫化物固溶体光触媒水素生成反応を進行させる光照射による光電着により前記固溶体にＲｕ、Ｐｔ、ＲｈまたはＩｒ担持させＲｕ、Ｐｔ、ＲｈまたはＩｒ担持（ＣｕＡｇ）ＸＩｎ２ＸＺｎ２（１−２Ｘ）Ｓ２固溶体からなる光触媒を製造する方法であり、より好ましくは、（１０）光電着による（ＣｕＡｇ）ＸＩｎ２ＸＺｎ２（１−２Ｘ）Ｓ２固溶体へＲｕ、Ｐｔ、ＲｈまたはＩｒ担持させる行程を前記固溶体光触媒によりＳＯ３ ２−とＳ２−イオンが存在する水溶液から水素生成光分解を実施する前工程または行程中で進行させる前記（９）に記載のＲｕ、Ｐｔ、ＲｈまたはＩｒ担持（ＣｕＡｇ）ＸＩｎ２ＸＺｎ２（１−２Ｘ）Ｓ２固溶体からなる光触媒を製造する方法である。 The second of the present invention, (8) (CuAg) X In 2X Zn 2 (1-2X) S 2 ( where, X is 0.15 ± 0.02) range and the processing temperature 800 ° C. ± 0.99 ° C. The Heat treatment is performed under combined treatment conditions in the range of 3 hours or more and 37 hours or less, the specific surface area of the BET isothermal adsorption method is 0.9 m 2 / g or more and 3.6 m 2 / g or more, and the band gap is 2.0 ± 0.1 eV. (CuAg) X In 2X Zn 2 (1-2X) S 2 (where X is 0.15 ± 0. 0), and has the activity of generating hydrogen by photohydrolysis of an aqueous solution containing a sulfur compound. This is a method for producing a photocatalyst comprising a sulfide solid solution having the composition (02). Preferably, (9) (CuAg) X In 2X Zn 2 (1-2X) S 2 solid solution and Ru, Pt, at least SO 3 added chlorides Rh or Ir sulfide solid solution photocatalyst hydrogen generation photolysis solution 2- sulfide solid solution photocatalyst is added to an aqueous solution, and the solid solution is supported by Ru, Pt, Rh, or Ir by photo-deposition by light irradiation to advance the hydrogen-catalyzed hydrogen generation reaction. Ru, Pt, Rh, or Ir is supported (CuAg ) X In 2X Zn 2 (1-2X) S 2 solid solution, more preferably, (10) (CuAg) X In 2X Zn 2 (1-2X) S 2 solid solution by photo-deposition to Ru, Pt, Rh or hydrogen generation optical branching stroke to Ir supported from an aqueous solution to the presence of SO 3 2-and S 2- ions by the solid solution photocatalyst In the method for producing Ru, Pt, and Rh or Ir supported (CuAg) X In 2X Zn 2 (1-2X) photocatalyst comprising S 2 solid solution according to (9) By proceeding in a previous step or step in carrying out the is there.
発明の効果として、６１５ｎｍまでの広い波長域の可視光を利用できる水の光分解水素生成触媒系を構築できたことを挙げることができる。高効率な水素生成による光エネルギー変換系としてこのような長波長域までの光を利用できる系が見出されたことは全く驚くべきことである。 As an effect of the invention, it can be mentioned that a water photolysis hydrogen generation catalyst system capable of using visible light in a wide wavelength range up to 615 nm could be constructed. It is quite surprising that a system that can use light up to such a long wavelength range has been found as a light energy conversion system by highly efficient hydrogen generation.
先ず、本発明の評価機器、測定装置などを説明する。
Ａ．測定機器、実験装置の概要；
調製された硫黄固溶体類の分析；
１）硫化物固溶体の粉末の同定；Ｘ線回折(Rigaku；MiniFlex)による。
２）触媒の比表面積の測定；ＢＥＴ等温吸着法 (Coulter；SA3100) による。
３）紫外-可視-近赤外拡散反射スペクトル（ＤＲＳ）；紫外可視近赤外分光光度計(Jascow；UbestV-570)で測定。得られた拡散反射スペクトルは，Kubelka-Munk法により、吸収モードに変換
Ｂ．光触媒の活性測定：
１）図１に記載の、循環系Ｃ、発生水素ガス排気系Ｖ．Ｌ、発生ガス分析ガスクロマトグラフィーＧ、Ｃ、撹拌子ＭＸ、高温糟Ｔ．Ｂ、光源Ｌを配置した反応器Ｒ．Ｖを備えた閉鎖循環系。
２）水素生成光分解実験溶液；硫黄化合物を含む水溶液、好ましくは、ＳＯ３ ２−とＳ２−イオンが存在する水溶液、より好ましくは、還元剤であるＫ２ＳＯ３とＮａ２Ｓとの混合水溶液中（０．５Ｍ Ｋ２ＳＯ３＋０．１Ｍ Ｎａ２Ｓまたは、０．２５ＭＫ２ＳＯ３＋ ０．３５Ｍ Ｎａ２Ｓ）
３）生成した水素の定量；ガスクロマトグラフＧ．Ｃ(Shimazu; GC-8A, MS-5A column, TCD, Ar carrier)
４）光源Ｌ；３００ＷのＸｅ ランプ(ＩＬＣ technology；CERMAX LX-300)とCut-off filter (HOYA L42)を組み合わせた、４２０ｎｍより長波長の光源
５）太陽光シュミレーター（ＹＡＭＡＳＨＩＴＡ ＤＥＮＳＯ；ＹＳＳ−８０ＱＡ，ＡＭ１．５，１００ｍＷ／ｃｍ２）の光源を用いた活性の評価。（この場合、反応は開放系で行い、生成したガスは水上置換で定量した。）
First, an evaluation device, a measurement device, and the like of the present invention will be described.
A. Outline of measuring equipment and experimental equipment;
Analysis of prepared sulfur solid solutions;
1) Identification of sulfide solid solution powder; by X-ray diffraction (Rigaku; MiniFlex).
2) Measurement of specific surface area of catalyst; by BET isothermal adsorption method (Coulter; SA3100).
3) Ultraviolet-visible-near infrared diffuse reflectance spectrum (DRS); measured with an ultraviolet-visible near-infrared spectrophotometer (Jascow; UbestV-570). The obtained diffuse reflectance spectrum is converted into an absorption mode by the Kubelka-Munk method. Photocatalytic activity measurement:
1) Circulation system C, generated hydrogen gas exhaust system V. L, evolved gas analysis gas chromatography G, C, stirrer MX, high-temperature soot T. B, reactor R. with light source L. Closed circulatory system with V.
2) Hydrogen generation photolysis experimental solution; an aqueous solution containing a sulfur compound, preferably an aqueous solution containing SO 3 2− and S 2− ions, more preferably, K 2 SO 3 and Na 2 S as reducing agents. mixed solution (0.5M K 2 SO 3 + 0.1M Na 2 S or, 0.25MK 2 SO 3 + 0.35M Na 2 S)
3) Quantification of produced hydrogen; gas chromatograph G. C (Shimazu; GC-8A, MS-5A column, TCD, Ar carrier)
4) Light source L; 300 W Xe lamp (ILC technology; CERMAX LX-300) and Cut-off filter (HOYA L42) combined with a light source having a wavelength longer than 420 nm 5) Solar simulator (YAMASHITA DENSO; YSS-80QA, Evaluation of activity using a light source of AM 1.5, 100 mW / cm 2 ). (In this case, the reaction was carried out in an open system, and the generated gas was quantified by water replacement.)
硫黄固溶体の調製；
Ａ．（ＣｕＡｇ）０．１５Ｉｎ０．３Ｚｎ１．４Ｓ２固溶体の調製；
ＡｇＮＯ３（Tanaka Kikinzoku；９９．８％）１．９１ｇ、Ｉｎ（ＮＯ３）３・３．６Ｈ２Ｏ(Kojundo-kagaku；９９．９％)０．８２３−０．９０５ｇ（０−２０％過剰）,Ｚｎ（ＮＯ３）２・６Ｈ２Ｏ（Wako−Chemicals；９９．０％） ０．３２４ｇの混合水溶液１５０ｍＬ中にＣｕＣｌ（Kanto-kagaku；９５％ または その場で合成）１．１１ｇを添加した後、Ｈ２Ｓガスを導入して硫化物の沈殿を生成した。１５時間攪拌熟成した後、純水により濾過洗浄し、空気中で風乾させ、これを前駆体とした。得られた前駆体は後に示す表１−３に処理温度と処理時間〔（）内は昇温時間（ｈ）〕の熱処理条件で処理した。
表１−３では石英製アンプル中に真空封入して、また表２と３では、前駆体に硫黄を混合し、硫黄雰囲気中で熱処理した場合を示した。表３には、（ＣｕＩｎ）０．０９Ｚｎ１．８２Ｓ２固溶体及び（ＣｕＧａ）０．０９Ｚｎ１．８２Ｓ２固溶体について、対比のために記載した。
各表中にはバンドギャップ（ｅＶ）及びＨ２生成活性を、また、表１及び２には比表面積（ｍ２／ｇ）も記載した。
Preparation of sulfur solid solution;
A. Preparation of (CuAg) 0.15 In 0.3 Zn 1.4 S 2 solid solution;
AgNO 3 (Tanaka Kikinzoku; 99.8% ) 1.91g, In (NO 3) 3 · 3.6H 2 O (Kojundo-kagaku; 99.9%) 0.823-0.905g (0-20% excess ), Zn (NO 3) 2 · 6H 2 O (Wako-Chemicals; 99.0%) mixed solution 150mL during CuCl of 0.324g (Kanto-kagaku; 95%, or synthesized in situ) added 1.11g After that, H 2 S gas was introduced to form a sulfide precipitate. After stirring and aging for 15 hours, the solution was filtered and washed with pure water and air-dried in air to obtain a precursor. The obtained precursor was processed under the heat treatment conditions shown in Table 1-3, which will be described later, with the processing temperature and processing time [() is the temperature rising time (h)].
Table 1-3 shows a case where a vacuum ampule is enclosed in a quartz ampule, and Tables 2 and 3 show a case where sulfur is mixed with the precursor and heat-treated in a sulfur atmosphere. Table 3 shows the (CuIn) 0.09 Zn 1.82 S 2 solid solution and the (CuGa) 0.09 Zn 1.82 S 2 solid solution for comparison.
In each table, band gap (eV) and H 2 production activity are shown, and in Tables 1 and 2, specific surface area (m 2 / g) is also shown.
図２に熱処理条件７００℃（９７３Ｋ）で３５時間で得られた（ＣｕＡｇ）０．１５Ｉｎ０．３Ｚｎ１．４Ｓ２固溶体の拡散反射スペクトルを示した。 FIG. 2 shows a diffuse reflection spectrum of a (CuAg) 0.15 In 0.3 Zn 1.4 S 2 solid solution obtained in a heat treatment condition of 700 ° C. (973 K) in 35 hours.
Ｂ．表３に記載の比較実験用固溶体の調製；
１）（ＣｕＩｎ）０．０９Ｚｎ１．８２Ｓ２固溶体の調製；
Ｉｎ（ＮＯ３）３・５Ｈ２Ｏ（Kojundo-kagaku；９９．９９％）０．３５２ｇ、Ｚｎ（ＮＯ３）２・６Ｈ２Ｏ（Wako−Chemicals；９９．０％）０．３５２ｇ、ＣｕＣｌ（Kanto-kagaku；９５％ または その場で合成）０．０８９ｇを溶かした混合水溶液１５０ｍＬ中に、Ｈ２Ｓガスを導入して硫化物の沈殿を生成し、１５時間攪拌熟成した。その後は、（ＣｕＡｇ）０．１５Ｉｎ０．３Ｚｎ１．４Ｓ２固溶体の合成と同様の手順で行った。
２）（ＣｕＧａ）０．０９Ｚｎ１．８２Ｓ２固溶体の調製；
原料となる硫化物Ｃｕ２Ｓ（Kojundo-kagaku；９９％）０．０７６ｇ、 Ｇａ２Ｓ２（Kojundo-kagaku；９９．９９％）０．１１７ｇ（１０％過剰)、ＺｎＳ （Kojundo-kagaku；９９．９９９％）１．７７３ｇを混合した後、石英アンプル中に真空封入して９５０℃（１２２３Ｋ）で１０時間の熱処理を行った。
B. Preparation of solid solutions for comparative experiments as described in Table 3;
1) Preparation of (CuIn) 0.09 Zn 1.82 S 2 solid solution;
In (NO 3) 3 · 5H 2 O (Kojundo-kagaku; 99.99%) 0.352g, Zn (NO 3) 2 · 6H 2 O (Wako-Chemicals; 99.0%) 0.352g, CuCl ( Kanto-kagaku (95% or synthesized in situ) Into 150 mL of a mixed aqueous solution in which 0.089 g was dissolved, H 2 S gas was introduced to form a sulfide precipitate, and the mixture was aged and stirred for 15 hours. Thereafter, the same procedure as the synthesis of (CuAg) 0.15 In 0.3 Zn 1.4 S 2 solid solution was performed.
2) Preparation of (CuGa) 0.09 Zn 1.82 S 2 solid solution;
0.076 g of sulfide Cu 2 S (Kojundo-kagaku; 99%) as a raw material, 0.117 g (10% excess) of Ga 2 S 2 (Kojundo-kagaku; 99.99%), ZnS (Kojundo-kagaku; 99 .999%) 1.773 g was mixed, and then vacuum sealed in a quartz ampoule and heat-treated at 950 ° C. (1223 K) for 10 hours.
前記固溶体にＰｔ及びＲｕ助触媒を担持させた触媒の調製；
光生成した電荷の分離、酸化還元反応の反応場を分離することや速度論的因子を有利にさせるので、Ｐｔ、Ｒｕ、Ｒｈなどの貴金属を助触媒として担持させることは行われているが、光分解触媒系と助触媒との組み合わせの水の光分解における酸化還元反応に対する理論は確立されていない。このことは、これまでに見出されている水素生成反応に高活性を示す硫化物固溶体光触媒においても同様である。硫化物固溶体光触媒ではＰｔを助触媒として担持することで活性が飛躍的に向上することがわかっている。しかし、Ｐｔ以外の助触媒を担持させた場合の効果については、詳しく調べられていない。また、ＡｇＧａＳ２光触媒は、ＰｔではなくＲｈを助触媒として担持することで水素生成活性がより高くなることがわかっている（前記非特許文献１２）。そこで、（ＣｕＡｇ）０．１５Ｉｎ０．３Ｚｎ１．４Ｓ２固溶体をベースとして、先ずＰｔ助触媒の、そしてＲｕの助触媒の担持効果について調べた。これによりＲｈまたはＩｒ助触媒について類推した。
Preparation of a catalyst having Pt and Ru promoters supported on the solid solution;
Although separation of photogenerated charges, separation of the reaction field of redox reaction and kinetic factors are made advantageous, noble metals such as Pt, Ru, Rh are supported as promoters. No theory has been established for the redox reaction in the photolysis of water in the combination of photolysis catalyst system and cocatalyst. The same applies to sulfide solid solution photocatalysts that have been found to be highly active in the hydrogen production reaction. It has been found that the activity of the sulfide solid solution photocatalyst is dramatically improved by supporting Pt as a promoter. However, the effect of loading a promoter other than Pt has not been investigated in detail. In addition, it has been found that the AgGaS 2 photocatalyst has higher hydrogen generation activity by supporting Rh instead of Pt as a cocatalyst (Non-patent Document 12). Therefore, based on the (CuAg) 0.15 In 0.3 Zn 1.4 S 2 solid solution, first, the supporting effect of the Pt promoter and the Ru promoter was examined. This gave an analogy for Rh or Ir promoters.
Ｐｔ助触媒の（ＣｕＡｇ）０．１５Ｉｎ０．３Ｚｎ１．４Ｓ２固溶体への担持は、前記水素生成光分解実験溶液混合水溶液（０．５Ｍ Ｋ２ＳＯ３＋０．１Ｍ Ｎａ２Ｓ）中にて光触媒反応中に光電着する処方により行った。表１に、Ｐｔ（０．５重量％）／（ＣｕＡｇ）０．１５Ｉｎ０．３Ｚｎ１．４Ｓ２固溶体触媒０．３ｇを添加し、前記水素生成光分解実験溶液を充填した図１に記載の閉鎖循環系において、前記光源として３００ＷのＸｅ ランプを用い、前記カットフィルターを介して４２０ｎｍより長波長側の光を照射して水素生成を測定した結果を示す。 The Pt cocatalyst supported on (CuAg) 0.15 In 0.3 Zn 1.4 S 2 solid solution was mixed with the hydrogen generation photolysis experimental solution mixed aqueous solution (0.5M K 2 SO 3 + 0.1M Na 2 S). It was carried out according to a formulation that photo-deposits during the photocatalytic reaction. 1 in which 0.3 g of Pt (0.5 wt%) / (CuAg) 0.15 In 0.3 Zn 1.4 S 2 solid solution catalyst was added and filled with the hydrogen generation photolysis experimental solution. In the closed circulation system described in 1), the result of measuring hydrogen generation by using a 300 W Xe lamp as the light source and irradiating light having a wavelength longer than 420 nm through the cut filter is shown.
前記従来の８５０℃（１１２３Ｋ）よりも低温の、７５０℃（１０２３Ｋ）（実験２），６５０℃（９２３Ｋ）（実験３）で熱処理した固溶体では、それぞれ表面積が大きくなった。表1の実験１−３では水素生成活性はより低温で合成するに従い、低下した。これは、低温の熱処理により、粒子サイズは小さくなるが、結晶性が低下してしまうことが原因でるものと考えられた。そこで低温熱処理においても、結晶性の高い粒子を得るために、熱処理時間を比較的長時間の２０時間（実験４）または３５時間（実験５）の熱処理を行った。その結果、表１から理解されるように、比較的大きな表面積を維持し、かつ水素生成活性が向上した。 In the solid solutions heat-treated at 750 ° C. (1023 K) (Experiment 2) and 650 ° C. (923 K) (Experiment 3), which are lower than the conventional 850 ° C. (1123 K), the surface area was increased. In Experiment 1-3 of Table 1, the hydrogen generation activity decreased as it was synthesized at a lower temperature. This was thought to be due to the decrease in crystallinity, although the particle size was reduced by low-temperature heat treatment. Therefore, in order to obtain particles having high crystallinity even in the low temperature heat treatment, heat treatment was performed for a relatively long heat treatment time of 20 hours (experiment 4) or 35 hours (experiment 5). As a result, as understood from Table 1, a relatively large surface area was maintained and the hydrogen generation activity was improved.
熱処理温度を比較的低下させ、比表面積の大きな（ＣｕＡｇ）ＸＩｎ２ＸＺｎ２（１−２Ｘ）Ｓ２固溶体を、焼成持の硫黄の消失を防ぐ硫黄雰囲気で熱処理して得たものの水素生成活性活性効果を測定した結果を表２に示す。 Heat treatment temperature relatively decreases the, big specific surface area (CuAg) X In 2X Zn 2 (1-2X) S 2 solid solution, baking lifting of those obtained by heat treatment at a sulfur atmosphere to prevent the loss of sulfur hydrogen generation activity The results of measuring the activity effect are shown in Table 2.
実験６と実験７−９との対比から、（ＣｕＡｇ）０．１５Ｉｎ０．３Ｚｎ１．４Ｓ２固溶体の前駆体に硫黄添加し、硫黄雰囲気中で熱処理することにより、比表面積は少し低下するが、Ｈ２生成活性が向上することが分かった。 From the comparison between Experiment 6 and Experiment 7-9, the specific surface area is slightly increased by adding sulfur to the precursor of (CuAg) 0.15 In 0.3 Zn 1.4 S 2 solid solution and heat-treating it in a sulfur atmosphere. reduced to, but it was found that H 2 generation activity is improved.
本発明の（ＣｕＡｇ）ＸＩｎ２ＸＺｎ２（１−２Ｘ）Ｓ２固溶体にＲｕ助触媒を担持させた場合の、助触媒Ｒｕと組み合わせた場合の水素生成活性に対する効果を調べた。Ｒｕを種々の熱処理条件により得られた固溶体光触媒に担持させ、それを用いて可視光照射下で水素生成反応を実施した場合のＨ２生成活性の測定結果を表３に示す。従来の熱処理条件〔８５０℃（１１２３Ｋ）で５時間〕で合成した（ＣｕＡｇ）０．１５Ｉｎ０．３Ｚｎ１．４Ｓ２固溶体光触媒(表３ の実験１０)では、図３に示す水素生成反応の経時変化のように、助触媒未担持でほとんど水素生成に活性を示さないが、Ｒｕを助触媒として担持することで、飛躍的に活性が向上することがわかった。反応初期での水素生成活性は５９２μｍｏｌ／ｈでありＰｔ担持の場合と同様に高い活性が得られた。しかし、反応初期で失活してしまい、反応５時間目以降では２４０μｍｏｌ／ｈと半分以下まで活性が低下してしまった。 The effect on the hydrogen generation activity when the Ru promoter was supported on the (CuAg) X In 2X Zn 2 (1-2X) S 2 solid solution of the present invention in combination with the promoter Ru was investigated. Table 3 shows the measurement results of the H 2 production activity when Ru is supported on a solid solution photocatalyst obtained under various heat treatment conditions and a hydrogen production reaction is carried out under irradiation with visible light. (CuAg) 0.15 In 0.3 Zn 1.4 S 2 solid solution photocatalyst (experiment 10 in Table 3) synthesized under conventional heat treatment conditions [850 ° C. (1123 K) for 5 hours] produces hydrogen as shown in FIG. It was found that, as with the change over time of the reaction, the cocatalyst was not loaded and showed little activity for hydrogen generation, but by loading Ru as a cocatalyst, the activity was dramatically improved. The hydrogen generation activity at the initial stage of the reaction was 592 μmol / h, and a high activity was obtained as in the case of carrying Pt. However, it was deactivated at the initial stage of the reaction, and after 5 hours of the reaction, the activity dropped to 240 μmol / h, which was less than half.
Ｒｕの担持方法によるＨ２活性、特に失活特性に対する効果の考察；
通常、Ｒｕ助触媒の担持は、Ｋ２ＳＯ３とＮａ２Ｓの混合水溶液に必要量のＲｕＣｌ３水溶液（ＲｕＣｌ３は溶けていない）を添加し、光触媒反応中に触媒表面上に光電着させている。
しかし、濃度の高いＮａ２Ｓ水溶液中では、Ｒｕがしっかりと触媒上へ光電着されていない可能性が考えられる。そこで、あらかじめＫ２ＳＯ３水溶液中で光電着し、その後Ｎａ２Ｓを加えて反応を行った（表３、実験１１）。その結果を図４に示す。初期活性で比較すると、図３の通常の担持条件よりも活性は若干低下しているが、比較的高い活性で水素を生成し、通常の担持条件で見られるような反応初期での極端な失活が抑制されていた。
Consideration of the effect on the H 2 activity, particularly the deactivation characteristics, by the Ru loading method;
Usually, the Ru promoter is supported by adding a necessary amount of RuCl 3 aqueous solution (RuCl 3 is not dissolved) to a mixed aqueous solution of K 2 SO 3 and Na 2 S, and performing photo-adsorption on the catalyst surface during the photocatalytic reaction. ing.
However, in a high concentration Na 2 S aqueous solution, there is a possibility that Ru is not photo-adhered firmly onto the catalyst. Therefore, photo-deposition was carried out in advance in a K 2 SO 3 aqueous solution, and then reaction was performed by adding Na 2 S (Table 3, Experiment 11). The result is shown in FIG. When compared with the initial activity, the activity is slightly lower than the normal loading conditions in FIG. 3, but hydrogen is generated at a relatively high activity, resulting in an extreme loss at the initial stage of the reaction as seen under normal loading conditions. Life was suppressed.
次に、従来の合成条件(熱処理:８５０℃（１１２３Ｋ）、５時間)とは異なり、より低温で長時間で熱処理、または硫黄雰囲気中でより低温で熱処理して合成した固溶体光触媒に関しても、Ｒｕを同様の手順で担持して反応を行った。図５（表３、実験１２），６（表３、実験１３）に示すように、合成方法を改良しＲｕをあらかじめＫ２ＳＯ３水溶液中で光電着させた（ＣｕＡｇ）０．１５Ｉｎ０．３Ｚｎ１．４Ｓ２固溶体光触媒では、非常に高い活性で、失活せずに水素を生成することがわかった。このように高い活性を維持したまま水素を生成し続けることが可能な他の光触媒としては、Ｐｔを担持したＣｄＳのみ知られている。しかし、この触媒は有毒なＣｄを含むことからも、有害な物質を含まないＲｕを担持した（ＣｕＡｇ）０．１５Ｉｎ０．３Ｚｎ１．４Ｓ２固溶体光触媒の発見は、非常に興味深い。 Next, unlike conventional synthesis conditions (heat treatment: 850 ° C. (1123 K), 5 hours), a solid solution photocatalyst synthesized by heat treatment at a lower temperature for a longer time or heat treatment at a lower temperature in a sulfur atmosphere is also used for Ru. Was carried out in the same procedure to carry out the reaction. As shown in FIGS. 5 (Table 3, Experiment 12) and 6 (Table 3, Experiment 13), the synthesis method was improved, and Ru was previously photo-deposited in a K 2 SO 3 aqueous solution (CuAg) 0.15 In 0 .3 Zn 1.4 S 2 solid solution photocatalyst was found to produce hydrogen with very high activity and without deactivation. As another photocatalyst capable of continuously generating hydrogen while maintaining high activity in this way, only CdS carrying Pt is known. However, since this catalyst contains toxic Cd, the discovery of a (CuAg) 0.15 In 0.3 Zn 1.4 S 2 solid solution photocatalyst carrying Ru that does not contain harmful substances is very interesting.
次に、Ｒｕ助触媒の担持効果が、他の固溶体光触媒においても同じように発現するかを（ＣｕＩｎ）０．０９Ｚｎ１．８２Ｓ２固溶体（熱処理:８５０℃（１１２３Ｋ）、５時間)（表３、実験１５）および（ＣｕＧａ）０．０９Ｚｎ１．８２Ｓ２(熱処理：８５０℃（１１２３Ｋ ５時間)固溶体（表３、実験１６）について調べてみた。それぞれの水素生成反応の経時変化を図７，８に示す。ＲｕをあらかじめＫ２ＳＯ３水溶液中で光電着させたこれらの固溶体は、比較的定常的に水素を生成し続けることが可能であり、Ｒｕ助触媒の担持効果が発現することがわかった。水素生成活性は、（ＣｕＩｎ）０．０９Ｚｎ１．８２Ｓ２固溶体で７０６μｍｏｌ／ｈと高い活性を示した。
以上の結果から、Ｒｕを助触媒として担持することで、Ｐｔを助触媒として担持した場合と同様に、水素生成活性が飛躍的に向上することがわかった。
Next, whether the loading effect of the Ru cocatalyst appears in the same manner in other solid solution photocatalysts (CuIn) 0.09 Zn 1.82 S 2 solid solution (heat treatment: 850 ° C. (1123 K), 5 hours) ( Table 3, Experiment 15) and (CuGa) 0.09 Zn 1.82 S 2 (Heat treatment: 850 ° C. (1123 K, 5 hours) solid solution (Table 3, Experiment 16) were examined. 7 and 8. These solid solutions in which Ru has been photo-deposited in advance in a K 2 SO 3 aqueous solution can continue to generate hydrogen relatively stably, and the effect of supporting the Ru promoter is effective. The hydrogen generation activity of the (CuIn) 0.09 Zn 1.82 S 2 solid solution was as high as 706 μmol / h.
From the above results, it was found that by supporting Ru as a cocatalyst, the hydrogen generation activity is dramatically improved, as in the case of supporting Pt as a cocatalyst.
次に、Ｒｕ（０．５重量％）をあらかじめＫ２ＳＯ３水溶液中で光電着させた（ＣｕＡｇ）０．１５Ｉｎ０．３Ｚｎ１．４Ｓ２固溶体光触媒(熱処理：７００℃（９７３Ｋ ３５時間）による擬似太陽光照射下での水素生成反応の結果を図９に示す。擬似太陽光照射下においても比較的高い活性で水素を生成した（１０．３ｍＬ／ｈ）。４０時間の光照射でもほとんど失活せずに水素を生成し続けた。この水素生成反応に高い活性を示す（ＣｕＡｇ）０．１５Ｉｎ０．３Ｚｎ１．４Ｓ２固溶体光触媒の拡散反射スペクトルを図２に示す。この固溶体は、６１５ｎｍまでの幅広い可視光を利用することができる。吸収端から見積もられたバンドギャップは２．０ｅＶとなった。 Next, Ru (0.5 wt%) was photo-deposited in advance in a K 2 SO 3 aqueous solution (CuAg) 0.15 In 0.3 Zn 1.4 S 2 solid solution photocatalyst (heat treatment: 700 ° C. (973K 35 9 shows the result of the hydrogen generation reaction under simulated sunlight irradiation (time), and produced hydrogen with relatively high activity even under simulated sunlight irradiation (10.3 mL / h). However, it continued to produce hydrogen with almost no deactivation, and the diffuse reflection spectrum of the (CuAg) 0.15 In 0.3 Zn 1.4 S 2 solid solution photocatalyst showing high activity in this hydrogen production reaction is shown in FIG. This solid solution can utilize a wide range of visible light up to 615 nm, and the band gap estimated from the absorption edge is 2.0 eV.
本発明の活用例として、太陽光の大部分を構成する可視光、特に６１５ｎｍまでの可視光を利用できる、将来有望なクリーンなエネルギー系を構築できる水素の生成系を、クリーンなエネルギー変換系を設計できる極めて有望なエネルギー技術に適用できる。疑似太陽光照射下で得られた水素生成反応の安定性は、実用性を示すものである。 As an application example of the present invention, a hydrogen generation system capable of constructing a promising clean energy system that can use visible light that constitutes most of sunlight, particularly visible light up to 615 nm, and a clean energy conversion system. It can be applied to highly promising energy technologies that can be designed. The stability of the hydrogen production reaction obtained under simulated sunlight irradiation shows practicality.
Ｖ．Ｌ 真空ライン Ｇ 圧力計 Ｃ 循環器 Ｔ．Ｂ 高温槽 Ｓ スターラー
ＭＸ 撹拌子 Ｌ 可視光（λ＞４２０ｎｍ） Ｒ．Ｖ 反応容器
Ｌ．Ｃ リービッヒ冷却管 Ｇ．Ｃ ガスクロマトグラフィー
V. L Vacuum line G Pressure gauge C Circulator T. B High-temperature bath S Stirrer MX Stirrer L Visible light (λ> 420 nm) V reaction vessel C. Liebig cooling pipe C Gas chromatography
Claims (10)
The process of supporting Ru, Pt, Rh, or Ir on (CuAg) X In 2X Zn 2 (1-2X) S 2 solid solution by photo- deposition is carried out from an aqueous solution containing SO 3 2− and S 2− ions by the solid solution photocatalyst. producing Ru, Pt, and Rh or Ir supported (CuAg) X in 2X Zn 2 (1-2X) photocatalyst comprising S 2 solid solution according to generate photodecomposition to claim 9 by proceeding in a previous step or step in implementing Method.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007144304A (en) * | 2005-11-28 | 2007-06-14 | Tokyo Univ Of Science | Zns-cux solid solution photocatalyst showing high activity for hydrogen generation under sunlight irradiation from aqueous solution containing sulfur compound |
| CN100384739C (en) * | 2006-05-23 | 2008-04-30 | 南开大学 | ZnIn2S4 nano materials and their synthesis method and application |
| CN110302805A (en) * | 2019-07-16 | 2019-10-08 | 福建师范大学福清分校 | A kind of single layer composite visible light catalytic material and preparation method thereof |
| CN115090299A (en) * | 2022-07-25 | 2022-09-23 | 陕西科技大学 | ZnIn with sulfur defect 2 S 4 Preparation method of photocatalyst and application of photocatalyst in degrading antibiotics |
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2004
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007144304A (en) * | 2005-11-28 | 2007-06-14 | Tokyo Univ Of Science | Zns-cux solid solution photocatalyst showing high activity for hydrogen generation under sunlight irradiation from aqueous solution containing sulfur compound |
| CN100384739C (en) * | 2006-05-23 | 2008-04-30 | 南开大学 | ZnIn2S4 nano materials and their synthesis method and application |
| CN110302805A (en) * | 2019-07-16 | 2019-10-08 | 福建师范大学福清分校 | A kind of single layer composite visible light catalytic material and preparation method thereof |
| CN110302805B (en) * | 2019-07-16 | 2022-06-07 | 福建技术师范学院 | Single-layer composite visible light catalytic material and preparation method thereof |
| CN115090299A (en) * | 2022-07-25 | 2022-09-23 | 陕西科技大学 | ZnIn with sulfur defect 2 S 4 Preparation method of photocatalyst and application of photocatalyst in degrading antibiotics |
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