JP7069611B2 - Electrochemical cells and photosynthetic equipment - Google Patents

Electrochemical cells and photosynthetic equipment Download PDF

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JP7069611B2
JP7069611B2 JP2017176016A JP2017176016A JP7069611B2 JP 7069611 B2 JP7069611 B2 JP 7069611B2 JP 2017176016 A JP2017176016 A JP 2017176016A JP 2017176016 A JP2017176016 A JP 2017176016A JP 7069611 B2 JP7069611 B2 JP 7069611B2
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JP2019052340A (en
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直彦 加藤
康彦 竹田
真太郎 水野
達雄 深野
憲昭 杉本
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Toyota Central R&D Labs Inc
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Description

本発明は、電気化学セル及び光合成装置に関する。 The present invention relates to an electrochemical cell and a photosynthetic apparatus.

半導体を光吸収体、金属錯体を二酸化炭素還元触媒として、半導体から金属錯体へ励起電子が移動することによって反応が進行する人工光合成デバイスが開示されている。太陽光エネルギーのみを用いて水（Ｈ２Ｏ）から水素（Ｈ２）を、水（Ｈ２Ｏ）と二酸化炭素（ＣＯ２）から一酸化炭素（ＣＯ），ギ酸（ＨＣＯＯＨ），アルコール（ＣＨ３ＯＨ）等を合成する人工光合成のためには、酸化／還元触媒間に約２Ｖの電位差を印加することが必要である。 Disclosed is an artificial photosynthesis device in which a reaction proceeds by moving excited electrons from a semiconductor to a metal complex, using a semiconductor as a light absorber and a metal complex as a carbon dioxide reduction catalyst. Hydrogen (H 2 ) from water (H 2 O) and carbon monoxide (CO), formic acid (HCOOH), alcohol (CH) from water (H 2 O) and carbon dioxide (CO 2 ) using only solar energy. For artificial photosynthesis to synthesize 3 OH) and the like, it is necessary to apply a potential difference of about 2 V between the oxidation / reduction catalysts.

これを実現するために、アモルファスシリコン系３接合太陽電池（ａ－Ｓｉ ３Ｊ－ＳＣ）の両面に酸化／還元触媒が担持された光電極が用いられている（非特許文献１，２）。また、アモルファスシリコン系３接合太陽電池を用い、裏面（光入射面の反対側）に還元触媒を担持し、これと対向するように酸化触媒機能を持つ部材を含んだ酸化電極を配置して太陽電池の表面電極と接続した、いわば太陽電池と電気化学セルを一体化した人工光合成セルが用いられている（非特許文献３）。また、より高い効率を狙って、ＩＩＩ－Ｖ族化合物２接合太陽電池（ＩＩＩ－Ｖ ２Ｊ－ＳＣ）を用いた例もある（非特許文献４）。 In order to realize this, optical electrodes in which oxidation / reduction catalysts are supported on both sides of an amorphous silicon-based 3-junction solar cell (a-Si 3J-SC) are used (Non-Patent Documents 1 and 2). In addition, an amorphous silicon-based 3-junction solar cell is used, a reduction catalyst is supported on the back surface (opposite the light incident surface), and an oxidation electrode containing a member having an oxidation catalyst function is arranged so as to face the reduction catalyst. An artificial photosynthesis cell that integrates a solar cell and an electrochemical cell, which is connected to the surface electrode of the battery, is used (Non-Patent Document 3). In addition, there is also an example in which a III-V group compound 2-junction solar cell (III-V 2J-SC) is used for higher efficiency (Non-Patent Document 4).

S. Y. Reece, J. A. Hamel, K. Sung, T. D. Jarvi, A. J. Esswein, J. J. H. Pijpers, and D. G. Nocera, Science 334, 645 (2011)S. Y. Reece, J. A. Hamel, K. Sung, T. D. Jarvi, A. J. Esswein, J. J. H. Pijpers, and D. G. Nocera, Science 334, 645 (2011) T. Arai, S. Sato, and T. Morikawa, Energy Environ. Sci 8, 1998 (2015)T. Arai, S. Sato, and T. Morikawa, Energy Environ. Sci 8, 1998 (2015) J.-P. Becker, B. Turan, V. Smirnov, K. Welter, F. Urbain, J. Wolff, S. Haas and F. Finger, J. Mater. Chem. A 5, 4818 (2017)J.-P. Becker, B. Turan, V. Smirnov, K. Welter, F. Urbain, J. Wolff, S. Haas and F. Finger, J. Mater. Chem. A 5, 4818 (2017) G. Peharz, F. Dimroth, and U. Wittstadt, Int. J. Hydrogen Energy 32, 3248 (2007)G. Peharz, F. Dimroth, and U. Wittstadt, Int. J. Hydrogen Energy 32, 3248 (2007)

ところが、非特許文献１及び２では、３接合の太陽電池の両側に酸化触媒電極と還元電極を接合した構造が開示されている。還元電極には、ステンレススチールを用いており、還元電極側からは、酸化電極の水の酸化反応は目視で確認できない。したがって、還元電極側からは反応の不具合を確認することができない。一方、酸化電極側からは、透明導電膜付き（ＩＴＯ）ガラス基板上にナノ粒子触媒が形成されているため、水の酸化反応を確認できる。しかしながら、水溶液電解液と酸化電極を通過した光が太陽電池に照射されるため、太陽電池に照射される光強度が低下するため、変換効率が低くなる。 However, Non-Patent Documents 1 and 2 disclose a structure in which an oxidation catalyst electrode and a reduction electrode are bonded to both sides of a three-junction solar cell. Stainless steel is used for the reduction electrode, and the oxidation reaction of water in the oxidation electrode cannot be visually confirmed from the reduction electrode side. Therefore, it is not possible to confirm the defect of the reaction from the reduction electrode side. On the other hand, from the oxide electrode side, since the nanoparticle catalyst is formed on the glass substrate with a transparent conductive film (ITO), the oxidation reaction of water can be confirmed. However, since the light that has passed through the aqueous solution electrolytic solution and the oxide electrode is irradiated to the solar cell, the light intensity irradiated to the solar cell is lowered, so that the conversion efficiency is lowered.

また、非特許文献３及び４では、太陽電池は酸化電極と還元電極の外側にあり、水を通過せずに、直接太陽光が太陽電池に照射されるため、変換効率の低下はない。しかしながら、酸化電極、還元電極に不透明な金属電極を用いているため、電極の裏面からは水の酸化及び還元反応の様子を目視で確認できない。したがって、反応の不具合があっても、早急に確認できない欠点があった。 Further, in Non-Patent Documents 3 and 4, the solar cell is located outside the oxidation electrode and the reduction electrode, and the solar cell is directly irradiated with sunlight without passing through water, so that the conversion efficiency does not decrease. However, since an opaque metal electrode is used for the oxidation electrode and the reduction electrode, the state of water oxidation and reduction reaction cannot be visually confirmed from the back surface of the electrode. Therefore, even if there is a defect in the reaction, there is a drawback that it cannot be confirmed immediately.

本発明の１つの態様は、酸化触媒機能を持つ部材を含む酸化電極と、還元触媒機能を持つ部材を含む還元電極と、が対向して設置されており、前記酸化電極及び前記還元電極の少なくとも一方が透光性を有し、前記酸化電極と前記還元電極との間に電解液が導入されていることを特徴とする電気化学セルである。 In one aspect of the present invention, an oxidation electrode including a member having an oxidation catalyst function and a reduction electrode including a member having a reduction catalyst function are installed facing each other, and at least the oxidation electrode and the reduction electrode are installed. One is a light-transmitting electrochemical cell, which is characterized in that an electrolytic solution is introduced between the oxidizing electrode and the reducing electrode.

ここで、前記酸化電極及び前記還元電極の少なくとも一方の可視光波長領域における透過率が２０％以上であることが好適である。 Here, it is preferable that the transmittance in at least one of the oxidizing electrode and the reducing electrode in the visible light wavelength region is 20% or more.

また、前記酸化電極及び前記還元電極の間にバイアス電圧が印加されていることが好適である。 Further, it is preferable that a bias voltage is applied between the oxidation electrode and the reduction electrode.

本発明の別の態様は、上記電気化学セルを備え、前記酸化電極及び前記還元電極の間に太陽電池が電気的に接続されており、前記太陽電池によって前記バイアス電圧が印加されている光合成装置である。 Another aspect of the present invention is a photosynthetic device comprising the electrochemical cell, the solar cell is electrically connected between the oxidation electrode and the reduction electrode, and the bias voltage is applied by the solar cell. Is.

ここで、前記電解液は、リン酸又はホウ酸緩衝水溶液であることが好適である。 Here, it is preferable that the electrolytic solution is a phosphoric acid or boric acid buffered aqueous solution.

また、前記還元電極は、二酸化炭素（ＣＯ２）に対する還元機能を有し、前記酸化電極は、水（Ｈ２Ｏ）を酸化して酸素（Ｏ２）を発生させる酸化機能を有することが好適である。 Further, it is preferable that the reducing electrode has a reducing function for carbon dioxide (CO 2 ), and the oxidizing electrode has an oxidizing function for oxidizing water (H 2 O) to generate oxygen (O 2 ). Is.

また、前記還元電極は、水（Ｈ２Ｏ）を還元して水素（Ｈ２）を発生させる酸化機能を有し、前記酸化電極は、水（Ｈ２Ｏ）を酸化して酸素（Ｏ２）を発生させる酸化機能を有することが好適である。 Further, the reducing electrode has an oxidizing function of reducing water (H 2 O) to generate hydrogen (H 2 ), and the oxidizing electrode oxidizes water (H 2 O) to oxygen (O 2 ). ) Is preferable to have an oxidizing function.

本発明によれば、透光性を有する酸化電極又は還元電極を備えた電気化学セル及び光合成装置を提供することができる。 According to the present invention, it is possible to provide an electrochemical cell and a photosynthetic apparatus provided with a light-transmitting oxide electrode or a reduction electrode.

本発明の実施の形態における光合成装置の構成を示す図である。It is a figure which shows the structure of the photosynthesis apparatus in embodiment of this invention. 本発明の実施の形態における還元電極の構成を示す図である。It is a figure which shows the structure of the reduction electrode in embodiment of this invention. 本発明の実施の形態における酸化電極の構成を示す図である。It is a figure which shows the structure of the oxide electrode in embodiment of this invention. 本発明の実施例における反応の測定結果を示す図である。It is a figure which shows the measurement result of the reaction in the Example of this invention. 本発明の実施例における光合成装置の電流－電圧特性を示す図である。It is a figure which shows the current-voltage characteristic of the photosynthesis apparatus in the Example of this invention. 本発明の実施例におけるギ酸の生成の測定結果を示す図である。It is a figure which shows the measurement result of the production of formic acid in the Example of this invention. 本発明の実施例における酸化電極の透過特性の測定結果を示す図である。It is a figure which shows the measurement result of the transmission characteristic of the oxide electrode in the Example of this invention.

本発明の実施の形態における光合成装置１００は、図１に示すように、還元電極１０２、酸化電極１０４、電解液１０６、太陽電池セル１０８、窓材１１０及び枠材１１２を含んで構成される。 As shown in FIG. 1, the photosynthetic apparatus 100 according to the embodiment of the present invention includes a reducing electrode 102, an oxidizing electrode 104, an electrolytic solution 106, a solar cell 108, a window material 110, and a frame material 112.

還元電極１０２は、還元反応によって物質を還元するために利用される電極である。還元電極１０２は、図２の断面模式図に示すように、基板１０、透明導電層１２、集電配線１４及び還元触媒１６を含んで構成される。なお、図２は模式図であり、各層の膜厚や幅等は実際のものとは異なっている。 The reduction electrode 102 is an electrode used for reducing a substance by a reduction reaction. As shown in the schematic cross-sectional view of FIG. 2, the reduction electrode 102 includes a substrate 10, a transparent conductive layer 12, a current collecting wiring 14, and a reduction catalyst 16. Note that FIG. 2 is a schematic diagram, and the film thickness, width, and the like of each layer are different from the actual ones.

基板１０は、還元電極１０２を構造的に支持する部材である。基板１０は、特に材料が限定されるものではないが、還元電極１０２を透光性を有するようにするには、例えば、ガラス基板やプラスチック等とすることが好適である。 The substrate 10 is a member that structurally supports the reduction electrode 102. The material of the substrate 10 is not particularly limited, but in order to make the reducing electrode 102 translucent, for example, a glass substrate, plastic, or the like is preferable.

透明導電層１２は、還元電極１０２における集電を効果的にするために設けられる。透明導電層１２は、特に限定されるものではないが、酸化インジウム錫（ＩＴＯ）、フッ素ドープ酸化錫（ＦＴＯ）、酸化亜鉛（ＺｎＯ）等とすることが好適である。特に、熱的及び化学的な安定性を考慮するとフッ素ドープ酸化錫（ＦＴＯ）を用いることが好適である。 The transparent conductive layer 12 is provided in order to effectively collect current in the reducing electrode 102. The transparent conductive layer 12 is not particularly limited, but is preferably indium tin oxide (ITO), fluorine-doped tin oxide (FTO), zinc oxide (ZnO), or the like. In particular, considering thermal and chemical stability, it is preferable to use fluorine-doped tin oxide (FTO).

集電配線１４は、還元電極１０２における集電の効果を高めるために設けられる。すなわち、還元電極１０２を大面積化した場合、透明導電層１２のみでは還元電極１０２の全面において十分な反応を促進させるための導電性を確保できなくなるので、還元電極１０２の導電性を高めるために設けられる。集電配線１４は、例えば、間隔を置いて櫛形状に配置された線状のフィンガー電極と、フィンガー電極を更に集電するためのバス電極とを組み合わせた構成とすることができる。集電配線１４は、導電部１４ａ、第１シール部１４ｂ及び第２シール部１４ｃから構成することが好適である。導電部１４ａは、導電性の高い材料で構成され、金属を含む材料で構成することが好適である。例えば、銀（Ａｇ）、銅（Ｃｕ）等を含む材料で構成することが好適である。また、第１シール部１４ｂ及び第２シール部１４ｃは、導電部１４ａを化学的及び機械的に保護するために少なくとも導電部１４ａの一部を被覆するように設けられる。第１シール部１４ｂは、低融点のガラスコート材とすることができる。また、第２シール部１４ｃは、シリコーンゴム（脱オキシムタイプ、低分子シロキサン低減材、耐油・耐溶剤フロロシリコーン等）、ポリイソブチレン、ポリプロピレン、メタクリル（アクリル）、ポリカーボネート、フッ素樹脂（テフロン（登録商標））、エポキシ樹脂等の樹脂とすることができる。 The current collector wiring 14 is provided to enhance the effect of current collection on the reduction electrode 102. That is, when the area of the reduction electrode 102 is increased, the transparency for promoting a sufficient reaction cannot be ensured on the entire surface of the reduction electrode 102 only with the transparent conductive layer 12, so that the conductivity of the reduction electrode 102 can be increased. It will be provided. The current collecting wiring 14 can be configured by, for example, combining linear finger electrodes arranged in a comb shape at intervals and a bus electrode for further collecting current from the finger electrodes. The current collector wiring 14 is preferably composed of a conductive portion 14a, a first seal portion 14b, and a second seal portion 14c. The conductive portion 14a is made of a highly conductive material, and it is preferable that the conductive portion 14a is made of a material containing a metal. For example, it is preferably composed of a material containing silver (Ag), copper (Cu) and the like. Further, the first seal portion 14b and the second seal portion 14c are provided so as to cover at least a part of the conductive portion 14a in order to chemically and mechanically protect the conductive portion 14a. The first sealing portion 14b can be a glass coating material having a low melting point. The second seal portion 14c is made of silicone rubber (deoxime type, low molecular weight siloxane reducing material, oil resistant / solvent resistant fluorosilicone, etc.), polyisobutylene, polypropylene, methacryl (acrylic), polycarbonate, fluororesin (Teflon (registered trademark)). )), Resin such as epoxy resin can be used.

還元触媒１６は、還元触媒機能を有する材料を含んで構成される。還元触媒機能を有する材料は、例えば、白金（Ｐｔ）とすることができる。白金は、ナノコロイド溶液として集電配線１４が形成された透明導電層１２の表面上に担持することができる（例：国際特許公開ＷＯ２００５／０２３４６７Ａ１）。 The reduction catalyst 16 is configured to include a material having a reduction catalyst function. The material having a reduction catalytic function can be, for example, platinum (Pt). Platinum can be supported as a nano-colloidal solution on the surface of the transparent conductive layer 12 on which the current collector wiring 14 is formed (eg, International Patent Publication WO2005 / 023467A1).

酸化電極１０４は、酸化反応によって物質を酸化するために利用される電極である。酸化電極１０４は、図３の断面模式図に示すように、基板２０、透明導電層２２、集電配線２４及び酸化触媒２６を含んで構成される。なお、図３は模式図であり、各層の膜厚や幅等は実際のものとは異なっている。 The oxidation electrode 104 is an electrode used for oxidizing a substance by an oxidation reaction. As shown in the schematic cross-sectional view of FIG. 3, the oxidation electrode 104 includes a substrate 20, a transparent conductive layer 22, a current collecting wiring 24, and an oxidation catalyst 26. Note that FIG. 3 is a schematic diagram, and the film thickness, width, and the like of each layer are different from the actual ones.

基板２０は、酸化電極１０４を構造的に支持する部材である。基板２０は、特に材料が限定されるものではないが、酸化電極１０４を透光性を有するようにするには、例えば、ガラス基板やプラスチック等とすることが好適である。 The substrate 20 is a member that structurally supports the oxide electrode 104. The material of the substrate 20 is not particularly limited, but in order to make the oxide electrode 104 translucent, for example, a glass substrate, plastic, or the like is preferable.

透明導電層２２は、酸化電極１０４における集電を効果的にするために設けられる。透明導電層２２は、特に限定されるものではないが、酸化インジウム錫（ＩＴＯ）、フッ素ドープ酸化錫（ＦＴＯ）、酸化亜鉛（ＺｎＯ）等とすることが好適である。特に、熱的及び化学的な安定性を考慮するとフッ素ドープ酸化錫（ＦＴＯ）を用いることが好適である。 The transparent conductive layer 22 is provided in order to effectively collect current in the oxide electrode 104. The transparent conductive layer 22 is not particularly limited, but is preferably indium tin oxide (ITO), fluorine-doped tin oxide (FTO), zinc oxide (ZnO), or the like. In particular, considering thermal and chemical stability, it is preferable to use fluorine-doped tin oxide (FTO).

集電配線２４は、酸化電極１０４における集電の効果を高めるために設けられる。すなわち、酸化電極１０４を大面積化した場合、透明導電層２２のみでは酸化電極１０４の全面において十分な反応を促進させるための導電性を確保できなくなるので、酸化電極１０４の導電性を高めるために設けられる。集電配線２４は、例えば、間隔を置いて櫛形状に配置された線状のフィンガー電極と、フィンガー電極を更に集電するためのバス電極とを組み合わせた構成とすることができる。集電配線２４は、導電部２４ａ、第１シール部２４ｂ及び第２シール部２４ｃから構成することが好適である。導電部２４ａは、導電性の高い材料で構成され、金属を含む材料で構成することが好適である。例えば、銀（Ａｇ）、銅（Ｃｕ）等を含む材料で構成することが好適である。また、第１シール部２４ｂ及び第２シール部２４ｃは、導電部２４ａを化学的及び機械的に保護するために少なくとも導電部２４ａの一部を被覆するように設けられる。第１シール部２４ｂは、低融点のガラスコート材とすることができる。また、第２シール部２４ｃは、シリコーンゴム（脱オキシムタイプ、低分子シロキサン低減材、耐油・耐溶剤フロロシリコーン等）、ポリイソブチレン、ポリプロピレン、メタクリル（アクリル）、ポリカーボネート、フッ素樹脂（テフロン（登録商標））、エポキシ樹脂等の樹脂とすることができる。 The current collector wiring 24 is provided to enhance the effect of current collection on the oxide electrode 104. That is, when the area of the oxide electrode 104 is increased, the transparency for promoting a sufficient reaction cannot be ensured on the entire surface of the oxide electrode 104 only by the transparent conductive layer 22, so that the conductivity of the oxide electrode 104 can be increased. It will be provided. The current collecting wiring 24 can be configured by, for example, combining linear finger electrodes arranged in a comb shape at intervals and a bus electrode for further collecting current from the finger electrodes. The current collector wiring 24 is preferably composed of a conductive portion 24a, a first seal portion 24b, and a second seal portion 24c. The conductive portion 24a is made of a highly conductive material, and it is preferable that the conductive portion 24a is made of a material containing a metal. For example, it is preferably composed of a material containing silver (Ag), copper (Cu) and the like. Further, the first seal portion 24b and the second seal portion 24c are provided so as to cover at least a part of the conductive portion 24a in order to chemically and mechanically protect the conductive portion 24a. The first sealing portion 24b can be a glass coating material having a low melting point. The second seal portion 24c is made of silicone rubber (deoxime type, low molecular weight siloxane reducing material, oil resistant / solvent resistant fluorosilicone, etc.), polyisobutylene, polypropylene, methacryl (acrylic), polycarbonate, fluororesin (Teflon (registered trademark)). )), Resin such as epoxy resin can be used.

酸化触媒２６は、酸化触媒機能を有する材料を含んで構成される。酸化触媒機能を有する材料は、例えば、酸化イリジウム（ＩｒＯｘ）を含む材料とすることができる。酸化イリジウムは、ナノコロイド溶液として集電配線２４が形成された透明導電層２２の表面上に担持することができる(T.Arai et.al, Energy Environ. Sci 8, 1998 (2015))。 The oxidation catalyst 26 is composed of a material having an oxidation catalyst function. The material having an oxidation catalyst function can be, for example, a material containing iridium oxide (IrOx). Iridium oxide can be supported as a nanocolloidal solution on the surface of the transparent conductive layer 22 on which the current collector wiring 24 is formed (T. Arai et.al, Energy Environ. Sci 8, 1998 (2015)).

このように、本実施の形態では、還元電極１０２及び酸化電極１０４を可視光波長領域において透光性を有する構成とすることができる。ここで、可視光波長領域とは、４００ｎｍ以上７００ｎｍ以下の光の波長領域とする。また、可視光波長領域において透光性を有するとは、４００ｎｍ以上７００ｎｍ以下の光の波長領域において還元電極１０２及び酸化電極１０４に入射した光のうち少なくとも２０％以上を透過することを意味するものとする。 As described above, in the present embodiment, the reducing electrode 102 and the oxidizing electrode 104 can be configured to have translucency in the visible light wavelength region. Here, the visible light wavelength region is a wavelength region of light of 400 nm or more and 700 nm or less. Further, having translucency in the visible light wavelength region means that at least 20% or more of the light incident on the reduction electrode 102 and the oxidation electrode 104 is transmitted in the wavelength region of light of 400 nm or more and 700 nm or less. And.

なお、還元電極１０２及び酸化電極１０４の両方を可視光波長領域において透光性を有する構成とすることなく、少なくとも１つを可視光波長領域において透光性を有する構成とすればよい。この場合、還元電極１０２及び酸化電極１０４のうち透光性を持たないものは、従来の還元電極１０２又は酸化電極１０４とすればよい。還元電極１０２及び酸化電極１０４の少なくとも１つを可視光波長領域において透光性を有する構成とすることで、光合成装置１００における反応を目視で確認できるようになる。具体的には、反応の不具合を目視にて確認することができ、早急に対応できるようになる。 It should be noted that both the reducing electrode 102 and the oxidizing electrode 104 may not be configured to have translucency in the visible light wavelength region, but at least one may be configured to have translucency in the visible light wavelength region. In this case, of the reducing electrode 102 and the oxidizing electrode 104, those having no translucency may be the conventional reducing electrode 102 or the oxidizing electrode 104. By configuring at least one of the reducing electrode 102 and the oxidizing electrode 104 to have translucency in the visible light wavelength region, the reaction in the photosynthetic apparatus 100 can be visually confirmed. Specifically, it is possible to visually confirm the malfunction of the reaction, and it becomes possible to take immediate action.

本実施の形態における光合成装置１００は、還元電極１０２と酸化電極１０４を組み合わせて構成される。例えば、図１に示すように、還元電極１０２と酸化電極１０４を還元触媒１６及び酸化触媒２６が対向するように配置し、その間に反応物が溶解された電解液１０６を導入させる。反応物は、炭化化合物とすることができ、例えば、二酸化炭素（ＣＯ２）とすることができる。また、電解液は、リン酸緩衝水溶液やホウ酸緩衝水溶液とすることが好適である。具体的な構成例では、二酸化炭素（ＣＯ２）飽和リン酸緩衝液のタンクを設け、ポンプによって当該液を還元電極１０２と酸化電極１０４との間に設けられた間隙に供給し、還元反応によって生じたギ酸（ＨＣＯＯＨ）や酸素（Ｏ２）を外部の燃料タンクに回収する。 The photosynthetic apparatus 100 in the present embodiment is configured by combining a reducing electrode 102 and an oxidizing electrode 104. For example, as shown in FIG. 1, the reduction electrode 102 and the oxidation electrode 104 are arranged so that the reduction catalyst 16 and the oxidation catalyst 26 face each other, and the electrolytic solution 106 in which the reactant is dissolved is introduced between them. The reaction product can be a carbide compound, for example, carbon dioxide (CO 2 ). Further, the electrolytic solution is preferably a phosphate buffered aqueous solution or a boric acid buffered aqueous solution. In a specific configuration example, a tank of carbon dioxide (CO 2 ) saturated phosphate buffer solution is provided, and the solution is supplied to the gap provided between the reduction electrode 102 and the oxidation electrode 104 by a pump, and the solution is subjected to a reduction reaction. The generated formic acid (HCOOH) and oxygen (O 2 ) are recovered in an external fuel tank.

還元電極１０２と酸化電極１０４との間を電気的に接続し、適切なバイアス電圧を印加した状態とする。バイアス電圧を印加する手段は、特に限定されるものではなく、化学的電池（一次電池、二次電池等を含む）、定電圧源、太陽電池等が挙げられる。このとき、酸化電極１０４の集電配線２４に正極が接続され、還元電極１０２の集電配線１４に負極が接続される。 The reduction electrode 102 and the oxidation electrode 104 are electrically connected to each other, and an appropriate bias voltage is applied. The means for applying the bias voltage is not particularly limited, and examples thereof include chemical batteries (including primary batteries, secondary batteries, etc.), constant voltage sources, solar cells, and the like. At this time, the positive electrode is connected to the current collecting wiring 24 of the oxide electrode 104, and the negative electrode is connected to the current collecting wiring 14 of the reducing electrode 102.

本実施の形態では、太陽電池セル１０８を採用している。太陽電池セル１０８は、還元電極１０２及び酸化電極１０４に隣接して配置することができる。図１の例では、還元電極１０２と酸化電極１０４とを対向させた電気化学セルの還元電極１０２の背面に太陽電池セル１０８を配置し、太陽電池セル１０８の正極を酸化電極１０４に接続し、負極を還元電極１０２に接続している。 In this embodiment, the solar cell 108 is adopted. The solar cell 108 can be arranged adjacent to the reduction electrode 102 and the oxidation electrode 104. In the example of FIG. 1, the solar cell 108 is arranged on the back surface of the reducing electrode 102 of the electrochemical cell in which the reducing electrode 102 and the oxide electrode 104 face each other, and the positive electrode of the solar cell 108 is connected to the oxide electrode 104. The negative electrode is connected to the reduction electrode 102.

二酸化炭素（ＣＯ２）からギ酸（ＨＣＯＯＨ）等を合成する場合、水（Ｈ２Ｏ）は酸化されて二酸化炭素（ＣＯ２）に電子とプロトンを供給する。ｐＨ７付近では水（Ｈ２Ｏ）の酸化電位は０．８２Ｖ、還元電位は－０．４１Ｖ（何れもＮＨＥ）である。また、二酸化炭素（ＣＯ２）から一酸化炭素（ＣＯ）、ギ酸（ＨＣＯＯＨ）、メチルアルコール（ＣＨ３ＯＨ）への還元電位はそれぞれ－０．５３Ｖ，－０．６１Ｖ，－０．３８Ｖである。したがって、酸化電位と還元電位の電位差は１．２０～１．４３Ｖである。そこで、炭化化合物である二酸化炭素（ＣＯ２）を還元する場合、太陽電池セル１０８は、４つの結晶系シリコン太陽電池を直接に接続した結晶シリコン系４接合太陽電池や３つのアモルファス系シリコン太陽電池を直列に接続したアモルファスシリコン系３接合太陽電池とすることが好適である。 When synthesizing formic acid (HCOOH) or the like from carbon dioxide (CO 2 ), water (H 2 O) is oxidized to supply electrons and protons to carbon dioxide (CO 2 ). At around pH 7, the oxidation potential of water (H 2 O) is 0.82 V, and the reduction potential is −0.41 V (both are NHE). The reduction potentials of carbon dioxide (CO 2 ) to carbon monoxide (CO), formic acid (HCOOH), and methyl alcohol (CH 3 OH) are -0.53V, -0.61V, and -0.38V, respectively. .. Therefore, the potential difference between the oxidation potential and the reduction potential is 1.20 to 1.43 V. Therefore, when reducing carbon dioxide (CO 2 ), which is a carbonized compound, the solar cell 108 is a crystalline silicon 4-junction solar cell or three amorphous silicon solar cells in which four crystalline silicon solar cells are directly connected. It is preferable to use an amorphous silicon-based 3-junction solar cell in which the solar cells are connected in series.

ここで、還元電極１０２及び酸化電極１０４の両方が可視光波長領域にて透光性を有する場合、太陽電池セル１０８はいずれの側に配置してもよい。一方、還元電極１０２及び酸化電極１０４の一方のみが可視光波長領域にて透光性を有する場合、太陽電池セル１０８は可視光波長領域にて透光性を持たない側に配置することが好適である。すなわち、可視光波長領域にて透光性を有する側に太陽電池セル１０８を配置しないことによって、太陽電池セル１０８によって目視の視界を遮られることがなくなる。 Here, when both the reducing electrode 102 and the oxidizing electrode 104 have translucency in the visible light wavelength region, the solar cell 108 may be arranged on either side. On the other hand, when only one of the reducing electrode 102 and the oxidizing electrode 104 has translucency in the visible light wavelength region, it is preferable to arrange the solar cell 108 on the side having no translucency in the visible light wavelength region. Is. That is, by not arranging the solar cell 108 on the side having translucency in the visible light wavelength region, the solar cell 108 does not block the visual view.

太陽電池セル１０８に対しては、受光面側に窓材１１０を設けることが好適である。窓材１１０は、太陽電池セル１０８を保護する部材である。窓材１１０は、太陽電池セル１０８において発電に寄与する波長の光を透過する部材とし、例えば、ガラス、プラスチック等とすることができる。 For the solar cell 108, it is preferable to provide the window material 110 on the light receiving surface side. The window material 110 is a member that protects the solar cell 108. The window material 110 is a member that transmits light having a wavelength that contributes to power generation in the solar cell 108, and may be, for example, glass, plastic, or the like.

還元電極１０２、酸化電極１０４、太陽電池セル１０８及び窓材１１０は、枠材１１２によって構造的に支持される。 The reduction electrode 102, the oxide electrode 104, the solar cell 108, and the window material 110 are structurally supported by the frame material 112.

［実施例］
＜酸化電極の作製方法＞
まず、酸化イリジウム（ＩｒＯｘ）のナノコロイドを合成した(T. Arai, S. Sato, and T. Morikawa, Energy Environ. Sci 8, 1998 (2015))。２ｍＭの塩化イリジウム酸（ＩＶ）カリウム（Ｋ２ＩｒＣｌ６）水溶液５０ｍｌに１０ｗｔ％の水酸化ナトリウム（ＮａＯＨ）水溶液を加えてｐＨ１３に調整した黄色溶液を、ホットスターラーを用いて９０℃で２０分加熱した。これによって得られた青色溶液を氷水で１時間冷却した。さらに、冷やした溶液（２０ｍｌ）に３Ｍ硝酸（ＨＮＯ３）を滴下してｐＨ１に調整し、８０分攪拌し、酸化イリジウム（ＩｒＯｘ）のナノコロイド水溶液を得た。この溶液に１．５ｗｔ％ＮａＯＨ水溶液（１－２ｍｌ）を滴下してｐＨ１２に調整した。 [Example]
<Method of manufacturing oxide electrode>
First, nanocolloids of iridium oxide (IrOx) were synthesized (T. Arai, S. Sato, and T. Morikawa, Energy Environ. Sci 8, 1998 (2015)). A yellow solution adjusted to pH 13 by adding a 10 wt% sodium hydroxide (NaOH) aqueous solution to 50 ml of a 2 mM potassium (IV) chloride (K 2 IrCl 6 ) aqueous solution is heated at 90 ° C. for 20 minutes using a hot stirrer. bottom. The resulting blue solution was cooled with ice water for 1 hour. Further, 3M nitric acid (HNO 3 ) was added dropwise to the cooled solution (20 ml) to adjust the pH to 1, and the mixture was stirred for 80 minutes to obtain a nanocolloidal aqueous solution of iridium oxide (IrOx). A 1.5 wt% NaOH aqueous solution (1-2 ml) was added dropwise to this solution to adjust the pH to 12.

本実施例では、基板２０及び透明導電層２２は、ＩＴＯより化学的及び熱的に安定性が高いフッ素ドープ酸化錫（ＦＴＯ）透明導電膜付きのガラス（日本板硝子製ＳＡ－２５）を用いた。ＦＴＯである透明導電層２２上に、スクリーン印刷を適用して、銀（Ａｇ）のペーストを所望のパターンに塗布して、大気中において熱処理４５０℃を施して銀（Ａｇ）を焼結させて導電部２４ａを形成した。さらに、銀（Ａｇ）の配線上に、スクリーン印刷法を適用して、低融点ガラスペーストを用いてカバーガラスを塗布し、大気中において熱処理（４００℃）を施してカバーガラスを第１シール部２４ｂとして形成した。その上に、ディスペンサーを用いてシリコーン樹脂（ゴム）を塗布して、室温で乾燥させて第２シール部２４ｃを形成した。これによって、３層構造の集電配線２４を作製した。 In this embodiment, the substrate 20 and the transparent conductive layer 22 are made of glass with a fluorine-doped tin oxide (FTO) transparent conductive film (SA-25 manufactured by Nippon Sheet Glass), which is more chemically and thermally stable than ITO. .. Screen printing is applied on the transparent conductive layer 22 which is an FTO, a paste of silver (Ag) is applied to a desired pattern, and heat treatment is performed at 450 ° C. in the air to sinter the silver (Ag). The conductive portion 24a was formed. Further, a screen printing method is applied on the silver (Ag) wiring, a cover glass is applied using a low melting point glass paste, and heat treatment (400 ° C.) is applied in the air to attach the cover glass to the first sealing portion. Formed as 24b. A silicone resin (rubber) was applied onto the silicone resin (rubber) using a dispenser and dried at room temperature to form a second sealed portion 24c. As a result, the current collector wiring 24 having a three-layer structure was produced.

このように、集電配線２４が形成された透明導電層２２上にｐＨ１２に調整した酸化イリジウム（ＩｒＯｘ）のナノコロイド水溶液を塗布し、乾燥炉内において６０℃で４０分間保持して乾燥した。乾燥後、析出した塩を超純水で洗浄し、酸化触媒２６を形成した。このようにして、１０ｃｍ×１０ｃｍの大きさの酸化電極１０４を得た。このとき、酸化イリジウム（ＩｒＯｘ）のナノコロイド水溶液の塗布量（２５ｍｌ×１回、２回、３回／１０ｃｍ角）を変えて、３種類の酸化電極１０４を形成した。 In this way, a nanocolloidal aqueous solution of iridium oxide (IrOx) adjusted to pH 12 was applied onto the transparent conductive layer 22 on which the current collector wiring 24 was formed, and the mixture was held in a drying oven at 60 ° C. for 40 minutes for drying. After drying, the precipitated salt was washed with ultrapure water to form an oxidation catalyst 26. In this way, an oxide electrode 104 having a size of 10 cm × 10 cm was obtained. At this time, three types of oxide electrodes 104 were formed by changing the coating amount (25 ml × 1 time, 2 times, 3 times / 10 cm square) of the nanocolloidal aqueous solution of iridium oxide (IrOx).

＜還元電極の作製方法１＞
本実施例では、還元電極１０２は透光性をもたないルテニウム錯体ポリマー（ＲｕＣＰ）担持多孔質炭素還元電極（サイズ：１０ｃｍ×１０ｃｍ）とした（T. Arai, S. Sato, and T. Morikawa, Energy Environ. Sci 8, 1998 (2015)）。 <Method for manufacturing reduction electrode 1>
In this embodiment, the reducing electrode 102 is a ruthenium complex polymer (RuCP) -supported porous carbon reducing electrode (size: 10 cm × 10 cm) having no translucency (T. Arai, S. Sato, and T. Morikawa). , Energy Environ. Sci 8, 1998 (2015)).

まず、管状炉を用いて、多孔質炭素をアルゴン（Ａｒ）の雰囲気下において３５０℃で２時間予備加熱した。その多孔質炭素の表面上に、二酸化炭素（ＣＯ２）の還元触媒であるＲｕ錯体ポリマー（ＲｕＣＰ）を修飾した。具体的には、２５ｍｇの［Ｒｕ｛４，４’－ｄｉ（１Ｈ－ｐｒｒｒｏｌｙｌ－３－ｐｒｏｐｙｌｃａｒｂｏｎａｔｅ）－２，２’－ｂｉｐｙｒｉｄｉｎｅ｝（ＣＯ）（ＭｅＣＮ）Ｃｌ２］を３５ｍｌのアセトニトリル（ＭｅＣＮ）に溶解させてＲｕ錯体溶液を調製した。そして、２．５μｌのピロールを５０ｍｌのＭｅＣＮに溶解させた１．８４ｍｌのピロール溶液をＲｕ錯体溶液に投入後、塩化鉄（ＩＩＩ）（ＦｅＣｌ３）をエタノールに溶解した９ｍｌの０．２ＭＦｅＣｌ３溶液を滴下して混合した。ＦｅＣｌ３溶液の添加により、Ｆｅイオンによりピロールの重合反応を促進させて、Ｒｕ錯体ポリマー（ＲｕＣＰ）溶液が調製されたことで、Ｒｕ錯体溶液は赤色から黒色に変化した。このように生成された本溶液を４．６ｍｌ／１回の量で多孔質炭素担体に塗布して、常温で５分間真空乾燥した。この塗布、真空乾燥処理を１０回繰り返した。その後、超純水で洗浄して余分なＦｅＣｌ３を除去して乾燥した後、ＲｕＣＰで修飾された多孔質炭素担体を作製した。 First, using a tube furnace, the porous carbon was preheated at 350 ° C. for 2 hours in an atmosphere of argon (Ar). A Ru complex polymer (RuCP), which is a reduction catalyst for carbon dioxide (CO 2 ), was modified on the surface of the porous carbon. Specifically, 25 mg of [Ru {4,4'-di (1H-prrrollyl-3-ropylcarbonate) -2,2'-bipyridine} (CO) (MeCN) Cl 2 ] was added to 35 ml of acetonitrile (MeCN). It was dissolved to prepare a Ru complex solution. Then, a 1.84 ml pyrrole solution in which 2.5 μl of pyrrole was dissolved in 50 ml of MeCN was added to the Ru complex solution, and then 9 ml of a 0.2 MFeCl 3 solution in which iron (III) chloride (FeCl 3 ) was dissolved in ethanol. Was dropped and mixed. The addition of the FeCl 3 solution promoted the polymerization reaction of pyrrol with Fe ions to prepare a Ru complex polymer (RuCP) solution, whereby the Ru complex solution changed from red to black. The solution thus produced was applied to a porous carbon carrier in an amount of 4.6 ml / dose and vacuum dried at room temperature for 5 minutes. This coating and vacuum drying treatment were repeated 10 times. Then, it was washed with ultrapure water to remove excess FeCl 3 and dried, and then a porous carbon carrier modified with RuCP was prepared.

続いて、ＦＴＯである透明導電層上に、スクリーン印刷を適用して、銀（Ａｇ）のペーストを所望のパターンに塗布して、大気中において熱処理４５０℃を施して銀（Ａｇ）を焼結させて導電部を形成した。さらに、銀（Ａｇ）の配線上に、スクリーン印刷法を適用して、低融点ガラスペーストを用いてカバーガラスを塗布し、大気中において熱処理（４００℃）を施してカバーガラスを第１シール部として形成した。その上に、ディスペンサーを用いてシリコーン樹脂（ゴム）を塗布して、室温で乾燥させて第２シール部を形成した。これによって、３層構造の集電配線を作製した。そして、グラファイト系導電性接着剤を用いて、ルテニウム錯体ポリマー（ＲｕＣＰ）担持多孔質炭素を上記３層構造の集電配線付きＦＴＯ基板上に貼りつけた。 Subsequently, screen printing is applied on the transparent conductive layer which is an FTO, a silver (Ag) paste is applied to a desired pattern, and heat treatment is performed at 450 ° C. in the air to sinter the silver (Ag). To form a conductive portion. Further, a screen printing method is applied on the silver (Ag) wiring, a cover glass is applied using a low melting point glass paste, and heat treatment (400 ° C.) is applied in the air to attach the cover glass to the first sealing portion. Formed as. A silicone resin (rubber) was applied onto the silicone resin (rubber) using a dispenser and dried at room temperature to form a second seal portion. As a result, a current collector wiring having a three-layer structure was produced. Then, using a graphite-based conductive adhesive, the ruthenium complex polymer (RuCP) -supported porous carbon was attached onto the FTO substrate with the current collecting wiring having the above-mentioned three-layer structure.

＜還元電極の作製方法２＞
透光性を有する還元電極１０２の実施例としてナノ粒子のＰｔを担持した電極を作製した。すなわち、透光性を有する水電解による水素生成用の還元電極１０２を作成した。 <Method for manufacturing reduction electrode 2>
As an example of the light-transmitting reducing electrode 102, an electrode carrying nanoparticles Pt was produced. That is, a reduction electrode 102 for hydrogen generation by water electrolysis having translucency was prepared.

基板１０及び透明導電層１２は、フッ素ドープ酸化錫（ＦＴＯ）透明導電膜付きのガラスを用いた。塩化白金酸（Ｈ２ＰｔＣｌ６）のイソプロパノール溶液（濃度０．００５ｍｏｌ／ｌ）を調製し、スピンコート法（回転数：３００回転３０秒後６００回転１分）で透明導電層１２上に塗布した。塗布後、大気中４００℃１０分焼成した。本手法で、透明導電層１２が設けられた基板１０上に粒径２～１０ｎｍのナノ粒子Ｐｔが担持された。 For the substrate 10 and the transparent conductive layer 12, glass with a fluorine-doped tin oxide (FTO) transparent conductive film was used. An isopropanol solution (concentration 0.005 mol / l) of chloroplatinic acid (H 2 PtCl 6 ) was prepared and applied onto the transparent conductive layer 12 by a spin coating method (rotation speed: 300 rotations 30 seconds, 600 rotations 1 minute). .. After coating, it was calcined in the air at 400 ° C. for 10 minutes. In this method, nanoparticles Pt having a particle size of 2 to 10 nm were supported on the substrate 10 provided with the transparent conductive layer 12.

＜電気化学特性評価＞
本実施例では、二酸化炭素（ＣＯ２）還元反応と水（Ｈ２Ｏ）の酸化反応の電気化学特性の評価を行った。上記方法で形成した酸化電極（アノード電極）１０４とルテニウム錯体ポリマー（ＲｕＣＰ）担持多孔質炭素還元電極（カソード電極）を対向させて、その間隙にリン酸緩衝水溶液中で二酸化炭素（ＣＯ２）ガスをバブリングしながら供給した。リン酸緩衝水溶液は、Ｋ２ＨＰＯ４とＫＨ２ＰＯ４をモル比１：１で混合し、リン酸濃度０．１Ｍになるように超純水を用いて調製した。二酸化炭素（ＣＯ２）の還元反応と水（Ｈ２Ｏ）の酸化反応は、電気化学測定システム（北斗電工製ＨＡ－３００１Ａ）を用いて定電流モードで制御した。このとき、還元電極１０２と酸化電極１０４とを太陽電池セル１０８を介して接続した光合成装置１００とし、光照射して、水（Ｈ２Ｏ）の酸化反応で生成された酸素（Ｏ２）と二酸化炭素（ＣＯ２）の還元反応で生成されたギ酸（ＨＣＯＯＨ）をモニターし、電流－電圧特性を測定した。 <Electrochemical characterization>
In this example, the electrochemical properties of the carbon dioxide (CO 2 ) reduction reaction and the water (H 2 O) oxidation reaction were evaluated. The oxide electrode (anode electrode) 104 formed by the above method and the ruthenium complex polymer (RuCP) -supported porous carbon reduction electrode (cathode electrode) are opposed to each other, and carbon dioxide (CO 2 ) gas is placed in the gap between them in a phosphate buffered aqueous solution. Was supplied while bubbling. The phosphoric acid buffered aqueous solution was prepared by mixing K 2 HPO 4 and KH 2 PO 4 at a molar ratio of 1: 1 and using ultrapure water so that the phosphoric acid concentration was 0.1 M. The reduction reaction of carbon dioxide (CO 2 ) and the oxidation reaction of water ( H2O ) were controlled in a constant current mode using an electrochemical measurement system (HA-3001A manufactured by Hokuto Denko). At this time, the reducing electrode 102 and the oxidizing electrode 104 are connected to each other via the solar cell 108 to form a photosynthetic device 100, which is irradiated with light to generate oxygen (O 2 ) in the oxidation reaction of water (H 2 O). Oxygen (HCOOH) produced by the reduction reaction of carbon dioxide (CO 2 ) was monitored and the current-voltage characteristics were measured.

このとき、可視光波長領域において透光性を有する酸化電極１０４を通してリン酸緩衝水溶液における水（Ｈ２Ｏ）の酸化反応を観察することができた。すなわち、酸化電極１０４を通して水（Ｈ２Ｏ）の酸化反応で生成された酸素（Ｏ２）の泡を明瞭に観察することができた。 At this time, the oxidation reaction of water ( H2O ) in the phosphate buffered aqueous solution could be observed through the oxide electrode 104 having transparency in the visible light wavelength region. That is, it was possible to clearly observe the bubbles of oxygen (O 2 ) generated by the oxidation reaction of water (H 2 O) through the oxidation electrode 104.

図４は、酸化電極１０４と還元電極（カソード電極）間の電圧をモニターした結果を示す。図４に示すように、２ｍＡ／ｃｍ２及び３ｍＡ／ｃｍ２のいずれの定電流モードにおいても時間的に安定に二酸化炭素（ＣＯ２）還元反応と水（Ｈ２Ｏ）の酸化反応が持続することが確認できた。また、図５に示すように、還元電極１０２と酸化電極１０４とを太陽電池セル１０８を介して接続した光合成装置１００における電流－電圧特性が測定された。 FIG. 4 shows the result of monitoring the voltage between the oxide electrode 104 and the reduction electrode (cathode electrode). As shown in FIG. 4, the carbon dioxide (CO 2 ) reduction reaction and the water (H 2 O) oxidation reaction are sustained in a time-stable manner in any of the constant current modes of 2 mA / cm 2 and 3 mA / cm 2 . I was able to confirm that. Further, as shown in FIG. 5, the current-voltage characteristics in the photosynthetic apparatus 100 in which the reduction electrode 102 and the oxidation electrode 104 were connected via the solar cell 108 were measured.

また、図６は、二酸化炭素（ＣＯ２）還元反応で生成したギ酸（ＨＣＯＯＨ）をイオンクロマトグラフ（Ｔｈｅｒｍｏ製 ＩＣＳ－２１００）で定量した結果を示す。図６に示すように、ギ酸（ＨＣＯＯＨ）の生成量は時間の経過に伴って線形的に増加した。また、ファラデー効率は、８５％以上８８％以下であった。 In addition, FIG. 6 shows the results of quantification of formic acid (HCOOH) produced by the carbon dioxide (CO 2 ) reduction reaction by an ion chromatograph (ICS-2100 manufactured by Thermo). As shown in FIG. 6, the amount of formic acid (HCOOH) produced increased linearly with the passage of time. The Faraday efficiency was 85% or more and 88% or less.

＜電極の光学特性評価＞
本実施例における酸化電極１０４及び還元電極１０２の光学特性（直線透過率）を分光エリプソメーター（ＪＡウーラム社製 Ｍ２０００Ｕ）を用いて計測した。図７は、光学特性の測定結果を示す。なお、比較例として、市販のＴｉ基板上に酸化イリジウム（ＩｒＯｘ）をコーティングした酸化電極（Ａｎｏｄｉｃ１００：日進化成）及び市販のＰｔ箔状の触媒電極の光学特性を測定した。なお、図７中において、酸化イリジウム（ＩｒＯｘ）を１回塗布した例を（ＩｒＯｘ ２５ｍｌ×１）と示し、２回塗布した例を（ＩｒＯｘ ２５ｍｌ×２）と示し、３回塗布した例を（ＩｒＯｘ ２５ｍｌ×３）と示した。また、上記還元電極の作製方法２にて作成した還元電極１０２の例を（ナノ粒子Ｐｔ／ＦＴＯ）と示した。また、市販の酸化電極を（Ａｎｏｄｉｃ）と示し、Ｐｔ箔状の電極を（Ｐｔホイル）と示した。 <Evaluation of optical characteristics of electrodes>
The optical characteristics (linear transmittance) of the oxide electrode 104 and the reduction electrode 102 in this example were measured using a spectroscopic ellipsometer (M2000U manufactured by JA Woolam Co., Ltd.). FIG. 7 shows the measurement result of the optical characteristics. As a comparative example, the optical characteristics of an oxide electrode (Anodic100: Nikkeisei) coated with iridium oxide (IrOx) on a commercially available Ti substrate and a commercially available Pt foil-shaped catalyst electrode were measured. In FIG. 7, an example in which iridium oxide (IrOx) is applied once is shown as (IrOx 25 ml × 1), an example in which it is applied twice is shown as (IrOx 25 ml × 2), and an example in which it is applied three times (IrOx 25 ml × 2). It was shown as IrOx 25 ml × 3). Further, an example of the reduction electrode 102 produced by the method 2 for producing the reduction electrode is shown as (nanoparticles Pt / FTO). Further, the commercially available oxidation electrode was referred to as (Anodic), and the Pt foil-like electrode was referred to as (Pt foil).

図７に示すように、本実施例における酸化電極１０４及び還元電極の作製方法２にて作成した還元電極１０２の透過率は、いずれも、市販のＴｉ基板上に酸化イリジウム（ＩｒＯｘ）をコーティングした酸化電極（Ａｎｏｄｉｃ１００：日進化成）やＰｔ箔触媒電極よりも高く、視認性に優れていることが判明した。また、具体的には、本実施例の酸化電極１０４及び還元電極の作製方法２にて作成した還元電極１０２は、４００ｎｍ以上７００ｎｍ以下の光の波長領域において入射した光のうち少なくとも２０％以上を透過することが確認できた。 As shown in FIG. 7, the permeability of the oxide electrode 104 and the reduction electrode 102 produced in the method 2 for producing the reduction electrode in this example is such that iridium oxide (IrOx) is coated on a commercially available Ti substrate. It was found that it was higher than the oxidation electrode (Anodic100: Nikkei Seisei) and the Pt foil catalyst electrode and had excellent visibility. Specifically, the oxide electrode 104 of this embodiment and the reduction electrode 102 produced in the method 2 for producing the reduction electrode make up at least 20% or more of the incident light in the wavelength region of light of 400 nm or more and 700 nm or less. It was confirmed that it was transparent.

以上のように、水（Ｈ２Ｏ）の酸化反応（酸素ガス発生）及び水（Ｈ２Ｏ）の還元反応（水素ガス発生）を外部から目視で確認でき、電気化学セルの内部の反応を管理して、不具合箇所を早期に発見することができる。すなわち、還元電極１０２の還元電位と酸化電極１０４の酸化電位間の電位差に相当する光起電力を太陽電池セル１０８で供給し、太陽電池セル１０８の背面において還元電極１０２及び酸化電極１０４を対向させて配置し、そのどちらか一方を透光性を有する構成とすることで反応を確認し易い光合成装置を提供することができる。 As described above, the oxidation reaction of water (H 2 O) (generation of oxygen gas) and the reduction reaction of water (H 2 O) (generation of hydrogen gas) can be visually confirmed from the outside, and the reaction inside the electrochemical cell can be observed. It can be managed and the defective part can be found at an early stage. That is, the photovoltaic cell 108 supplies a photoelectromotive force corresponding to the potential difference between the reduction potential of the reduction electrode 102 and the oxidation potential of the oxidation electrode 104, and the reduction electrode 102 and the oxidation electrode 104 face each other on the back surface of the solar cell 108. It is possible to provide a photosynthetic apparatus in which the reaction can be easily confirmed by arranging them in a row and making one of them having a translucent structure.

１０ 基板、１２ 透明導電層、１４ 集電配線、１４ａ 導電部、１４ｂ 第１シール部、１４ｃ 第２シール部、１６ 還元触媒、２０ 基板、２２ 透明導電層、２４ 集電配線、２４ａ 導電部、２４ｂ 第１シール部、２４ｃ 第２シール部、２６ 酸化触媒、１００ 光合成装置、１０２ 還元電極、１０４ 酸化電極、１０６ 電解液、１０８ 太陽電池セル、１１０ 窓材、１１２ 枠材。
10 substrate, 12 transparent conductive layer, 14 current collector wiring, 14a conductive part, 14b first seal part, 14c second seal part, 16 reduction catalyst, 20 substrate, 22 transparent conductive layer, 24 current collector wiring, 24a conductive part, 24b 1st seal part, 24c 2nd seal part, 26 Oxidation catalyst, 100 Photosynthesis device, 102 Reduction electrode, 104 Oxidation electrode, 106 Electrolyte, 108 Solar cell, 110 Window material, 112 Frame material.

Claims (6)

酸化触媒機能を持つ部材を含む酸化電極と、還元触媒機能を持つ部材を含む還元電極と、が対向して設置されており、
前記酸化電極及び前記還元電極の外側に前記酸化電極と前記還元電極に電気的に接続された太陽電池が設けられ、前記酸化電極、前記還元電極、前記太陽電池の順に配置されており、
前記酸化電極が波長４００ｎｍ以上７００ｎｍ以下の範囲において透過率が２０％以上の透光性を有し、前記酸化電極と前記還元電極との間に電解液が導入されていることを特徴とする電気化学セル。 An oxidation electrode including a member having an oxidation catalyst function and a reduction electrode including a member having a reduction catalyst function are installed facing each other.
A solar cell electrically connected to the oxidation electrode and the reduction electrode is provided outside the oxidation electrode and the reduction electrode, and the oxidation electrode, the reduction electrode, and the solar cell are arranged in this order.
The oxide electrode has a translucency of 20% or more in a wavelength range of 400 nm or more and 700 nm or less, and an electrolytic solution is introduced between the oxide electrode and the reduction electrode. Chemical cell. 請求項１に記載の電気化学セルであって、
前記酸化電極は、透明導電層付ガラス基板上にナノ粒子の酸化触媒を設けた構成を有することを特徴とする電気化学セル。 The electrochemical cell according to claim 1.
The oxidation electrode is an electrochemical cell having a structure in which an oxidation catalyst of nanoparticles is provided on a glass substrate with a transparent conductive layer. 請求項１又は２に記載の電気化学セルを備え、
前記太陽電池によってバイアス電圧が印加されていることを特徴とする光合成装置。 The electrochemical cell according to claim 1 or 2 is provided.
A photosynthetic apparatus characterized in that a bias voltage is applied by the solar cell. 請求項３に記載の光合成装置であって、
前記電解液は、リン酸又はホウ酸緩衝水溶液であることを特徴とする光合成装置。 The photosynthetic apparatus according to claim 3 .
The photosynthetic apparatus, wherein the electrolytic solution is a phosphoric acid or boric acid buffered aqueous solution. 請求項３又は４に記載の光合成装置であって、
前記還元電極は、二酸化炭素（ＣＯ２）に対する還元機能を有し、
前記酸化電極は、水（Ｈ２Ｏ）を酸化して酸素（Ｏ２）を発生させる酸化機能を有することを特徴とする光合成装置。 The photosynthetic apparatus according to claim 3 or 4 .
The reducing electrode has a reducing function for carbon dioxide (CO 2 ) and has a reducing function.
The oxidation electrode is a photosynthetic apparatus having an oxidizing function of oxidizing water (H 2 O) to generate oxygen (O 2 ). 請求項３又は４のいずれか１項に記載の光合成装置であって、
前記還元電極は、水（Ｈ２Ｏ）を還元して水素（Ｈ２）を発生させる還元機能を有し、
前記酸化電極は、水（Ｈ２Ｏ）を酸化して酸素（Ｏ２）を発生させる酸化機能を有することを特徴とする光合成装置。 The photosynthetic apparatus according to any one of claims 3 or 4 .
The reducing electrode has a reducing function of reducing water (H 2 O) to generate hydrogen (H 2 ).
The oxidation electrode is a photosynthetic apparatus having an oxidizing function of oxidizing water (H 2 O) to generate oxygen (O 2 ).
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