JP2021154260A - Catalyst for anode electrodes and cocatalyst for photo-anode electrodes - Google Patents
Catalyst for anode electrodes and cocatalyst for photo-anode electrodes Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims description 27
- 239000011941 photocatalyst Substances 0.000 claims abstract description 83
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 27
- 229910052742 iron Inorganic materials 0.000 claims abstract description 25
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 22
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 22
- 239000001301 oxygen Substances 0.000 claims abstract description 22
- 229910052700 potassium Inorganic materials 0.000 claims abstract description 15
- 238000004519 manufacturing process Methods 0.000 claims abstract description 8
- 239000003426 co-catalyst Substances 0.000 claims description 51
- 229910052748 manganese Inorganic materials 0.000 claims description 15
- 230000007062 hydrolysis Effects 0.000 claims description 12
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- 230000003287 optical effect Effects 0.000 claims description 11
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 39
- 239000010936 titanium Substances 0.000 description 30
- 239000010410 layer Substances 0.000 description 23
- 238000000034 method Methods 0.000 description 23
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 22
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- 239000002245 particle Substances 0.000 description 21
- 239000011572 manganese Substances 0.000 description 17
- 239000000243 solution Substances 0.000 description 17
- 238000005868 electrolysis reaction Methods 0.000 description 14
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- 229910052751 metal Inorganic materials 0.000 description 12
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- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 8
- 238000000354 decomposition reaction Methods 0.000 description 8
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- 150000002739 metals Chemical class 0.000 description 6
- 150000004767 nitrides Chemical class 0.000 description 6
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 6
- -1 La 5 Ti 2 CuS 5 O 7 Chemical class 0.000 description 5
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- 229910052715 tantalum Inorganic materials 0.000 description 5
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- 239000008151 electrolyte solution Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
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- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 3
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- 150000003839 salts Chemical class 0.000 description 3
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- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 3
- 229910052720 vanadium Inorganic materials 0.000 description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
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- OBETXYAYXDNJHR-SSDOTTSWSA-M (2r)-2-ethylhexanoate Chemical compound CCCC[C@@H](CC)C([O-])=O OBETXYAYXDNJHR-SSDOTTSWSA-M 0.000 description 1
- ULUYRVWYCIOFRV-UHFFFAOYSA-K 2-ethylhexanoate;iron(3+) Chemical compound [Fe+3].CCCCC(CC)C([O-])=O.CCCCC(CC)C([O-])=O.CCCCC(CC)C([O-])=O ULUYRVWYCIOFRV-UHFFFAOYSA-K 0.000 description 1
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- 241000849798 Nita Species 0.000 description 1
- 229910052776 Thorium Inorganic materials 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- SPAMKTCAQPUYBY-UHFFFAOYSA-N [Mn+2].CCCCCC(=O)OCC Chemical compound [Mn+2].CCCCCC(=O)OCC SPAMKTCAQPUYBY-UHFFFAOYSA-N 0.000 description 1
- OBETXYAYXDNJHR-UHFFFAOYSA-N alpha-ethylcaproic acid Natural products CCCCC(CC)C(O)=O OBETXYAYXDNJHR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
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- 229910052804 chromium Inorganic materials 0.000 description 1
- QAEKNCDIHIGLFI-UHFFFAOYSA-L cobalt(2+);2-ethylhexanoate Chemical compound [Co+2].CCCCC(CC)C([O-])=O.CCCCC(CC)C([O-])=O QAEKNCDIHIGLFI-UHFFFAOYSA-L 0.000 description 1
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- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
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- ZUFQCVZBBNZMKD-UHFFFAOYSA-M potassium 2-ethylhexanoate Chemical compound [K+].CCCCC(CC)C([O-])=O ZUFQCVZBBNZMKD-UHFFFAOYSA-M 0.000 description 1
- 230000004044 response Effects 0.000 description 1
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- 229910001887 tin oxide Inorganic materials 0.000 description 1
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Abstract
Description
本発明は、水を分解して酸素を発生させる装置に備えられるアノード電極用触媒、及び光アノード電極用助触媒に関する。 The present invention relates to a catalyst for an anode electrode and a co-catalyst for a photoanode electrode provided in an apparatus for decomposing water to generate oxygen.
エネルギー資源の大半を占める化石燃料は有限であることから、光エネルギーを利用して、水を水素と酸素に分解することでエネルギー源とする研究が進められている。その際には光触媒が用いられることが通常である。
現在研究が進められている光触媒は、酸化物、酸窒化物、窒化物といった光半導体の表面に助触媒が担持され、助触媒を担持させることで光触媒の活性を向上させることができる。
Since fossil fuels, which account for most of the energy resources, are finite, research is underway to use light energy to decompose water into hydrogen and oxygen as an energy source. In that case, a photocatalyst is usually used.
In the photocatalyst currently under study, a co-catalyst is supported on the surface of a photo-semiconductor such as an oxide, an oxynitride, or a nitride, and the activity of the photocatalyst can be improved by supporting the co-catalyst.
水分解に用いられる光触媒用の助触媒としては、一般的に酸素発生用助触媒と水素発生用助触媒に大別される。
酸素発生用助触媒としては、Ni、Fe、Co等の金属が用いられてきたが、近年、より一層の光分解能力を求めて研究が進み、助触媒としても、CoとNiの酸化物、FeとNiの酸化物、等が開発された。そして非特許文献1には、Fe、Co、Niの複合酸化物が優れた助触媒となることが開示されている。
The photocatalyst co-catalyst used for water decomposition is generally roughly classified into an oxygen-evolving co-catalyst and a hydrogen-evolving co-catalyst.
Metals such as Ni, Fe, and Co have been used as auxiliary catalysts for oxygen generation, but in recent years, research has progressed in search of further photodecomposition ability, and oxides of Co and Ni have also been used as auxiliary catalysts. Oxides of Fe and Ni, etc. have been developed. Non-Patent Document 1 discloses that a composite oxide of Fe, Co, and Ni serves as an excellent co-catalyst.
本発明は、光触媒用の、新たな酸素生成用助触媒を提供することを課題とする。 An object of the present invention is to provide a new co-catalyst for oxygen generation for a photocatalyst.
本発明者らは、光触媒用の、新たな酸素生成用助触媒を提供すべく鋭意検討を重ねた結果、非特許文献1に開示された3元系の助触媒に、更にK(カリウム)及び/又はMn(マンガン)を添加することで、光触媒の性能が向上することを見出し、本発明を完成させた。
また、本発明者らは更に検討を進め、非特許文献1に開示された3元系の助触媒に、更にK(カリウム)及び/又はMn(マンガン)を添加した助触媒は、水の電気分解用のアノードと共に用いた場合には、それ自体が触媒として機能することも見出した。
本発明は以下の要旨を含む。
As a result of diligent studies to provide a new co-catalyst for oxygen generation for photocatalysts, the present inventors have added K (potassium) and K (potassium) to the ternary co-catalyst disclosed in Non-Patent Document 1. It was found that the performance of the photocatalyst was improved by adding / or Mn (manganese), and the present invention was completed.
Further, the present inventors further studied, and the co-catalyst in which K (potassium) and / or Mn (manganese) was further added to the ternary co-catalyst disclosed in Non-Patent Document 1 is water electrolysis. It has also been found that when used with a decomposition anode, it itself functions as a catalyst.
The present invention includes the following gist.
(1)Fe、Ni、Co、M及び酸素、を含むアノード電極用触媒。
但し前記MはK及びMnから選択される。
(2)前記Fe、Ni及びCoの合計重量に対する前記Mの重量比が、0.001以上3以下である、(1)に記載のアノード電極用触媒。
(3)(1)又は(2)に記載のアノード電極用触媒と光触媒と、を含む光電極。
(4)Fe、Ni、Co、M及び酸素、を含む光アノード電極用助触媒。
但し前記MはK及びMnから選択される。
(5)前記Fe、Ni及びCoの合計重量に対する前記Mの重量比が、0.001以上3以下である、(4)に記載の光アノード電極用助触媒。
(6)Fe、Ni、Co、M及び酸素、を含む非水溶性錯体を基体上に塗布する塗布ステ
ップ、及び基体上に塗布した非水溶性錯体を加水分解する加水分解ステップ、を含む、アノード電極用触媒又は光アノード電極用助触媒の製造方法。
但し前記MはK及びMnから選択される。
(7)前記加水分解ステップにおける平均温度は200℃以下である、(6)に記載のアノード電極用触媒又は光アノード電極用助触媒の製造方法。
(1) A catalyst for an anode electrode containing Fe, Ni, Co, M and oxygen.
However, the M is selected from K and Mn.
(2) The catalyst for an anode electrode according to (1), wherein the weight ratio of M to the total weight of Fe, Ni and Co is 0.001 or more and 3 or less.
(3) A photoelectrode including the anode electrode catalyst and photocatalyst according to (1) or (2).
(4) A co-catalyst for a photoanode electrode containing Fe, Ni, Co, M and oxygen.
However, the M is selected from K and Mn.
(5) The co-catalyst for a photoanode electrode according to (4), wherein the weight ratio of M to the total weight of Fe, Ni and Co is 0.001 or more and 3 or less.
(6) Anode comprising a coating step of applying a water-insoluble complex containing Fe, Ni, Co, M and oxygen on a substrate, and a hydrolysis step of hydrolyzing the water-insoluble complex coated on the substrate. A method for producing a catalyst for an electrode or an auxiliary catalyst for a photoanode electrode.
However, the M is selected from K and Mn.
(7) The method for producing an anode electrode catalyst or a photoanode electrode co-catalyst according to (6), wherein the average temperature in the hydrolysis step is 200 ° C. or lower.
本発明によれば、光触媒用の、新たな酸素生成用助触媒を提供することができる。当該助触媒は、水の電気分解用のアノードと共に用いた場合には、それ自体が触媒として機能する。 According to the present invention, it is possible to provide a new co-catalyst for oxygen generation for a photocatalyst. The co-catalyst itself functions as a catalyst when used with an anode for electrolysis of water.
以下、本発明につき詳細に説明するが、以下に記載する構成要件の説明は、本発明の実施態様の一例(代表例)であり、本発明はこれらの内容に限定されるものではなく、その要旨の範囲内で種々変形して実施することができる。 Hereinafter, the present invention will be described in detail, but the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents. It can be implemented with various modifications within the scope of the abstract.
本発明に係る一実施形態は、光触媒を含むアノード電極用助触媒である。光アノード電極用助触媒とも称する。光アノード電極用助触媒は通常、光触媒に担持されることで、光触媒の酸素生成機能を飛躍的に向上することとなる。
本実施形態において光アノード電極用助触媒は、Fe、Ni、Co、M及び酸素、を含み、前記MはK及びMnから選択される。これら以外の成分を含んでいてもよく、含んでいなくてもよい。
本実施形態の助触媒は、通常これらの金属を含む複合体である。ここで複合体とは、これらの金属との間で、例えば物理的又は化学的に何らかの結合が生じ、一体化しているものをいう。そのため、単なるこれらの金属の混合物は、ここでいう複合体には含まない。複合体とするためには、これらの金属を単に混合するのみではなく、熱処理、機械的処理、化学的処理等を施すことが必要となる。
One embodiment according to the present invention is an auxiliary catalyst for an anode electrode including a photocatalyst. Also called a co-catalyst for optical anode electrodes. The cocatalyst for the photoanode electrode is usually supported on the photocatalyst, which dramatically improves the oxygen generation function of the photocatalyst.
In the present embodiment, the co-catalyst for the photoanode electrode contains Fe, Ni, Co, M and oxygen, and M is selected from K and Mn. Ingredients other than these may or may not be contained.
The co-catalyst of this embodiment is usually a complex containing these metals. Here, the complex refers to a complex in which, for example, some kind of physical or chemical bond is formed and integrated with these metals. Therefore, a mere mixture of these metals is not included in the complex here. In order to form a complex, it is necessary not only to mix these metals but also to perform heat treatment, mechanical treatment, chemical treatment and the like.
光アノード電極用助触媒は、Fe、Ni及びCoの合計重量に対する前記Mの重量比が、0.001以上3以下であることが好ましく、0.01以上1以下であることがより好ましい。特に、MがKの場合には、0.01以上0.4以下であることが好ましく、MがMnの場合には、0.01以上0.1以下であることが好ましい。上記範囲を充足することで、安定的に高い性能が得られる。光アノード電極用助触媒中のこれらの成分の重量はXRF、ICP法等を用いて測定することができる。
また、光アノード電極用助触媒中のFe、Ni、Coの重量比は特に限定されないが、Feに対し、Ni、Coがそれぞれ0.5以上2以下であってよく、0.8以上1.2以下であってよく、0.9以上1.1以下であってよい。
The weight ratio of M to the total weight of Fe, Ni and Co of the co-catalyst for the photoanode electrode is preferably 0.001 or more and 3 or less, and more preferably 0.01 or more and 1 or less. In particular, when M is K, it is preferably 0.01 or more and 0.4 or less, and when M is Mn, it is preferably 0.01 or more and 0.1 or less. By satisfying the above range, stable and high performance can be obtained. The weight of these components in the co-catalyst for the photoanode electrode can be measured by using XRF, ICP method or the like.
The weight ratio of Fe, Ni, and Co in the cocatalyst for the photoanode electrode is not particularly limited, but Ni and Co may be 0.5 or more and 2 or less, respectively, with respect to Fe, and 0.8 or more and 1. It may be 2 or less, and may be 0.9 or more and 1.1 or less.
本実施形態において、光アノード電極用助触媒はどのような形状であってもよく特に限定されないが、箔状であってよく、板状であってよく、粒子状であってよく、微粒子であってよい。微粒子である場合その粒子径は、光触媒への担持の容易性から通常1nm以上、好ましくは1.2nm以上、より好ましくは1.5nm以上である。また、通常25nm以下、好ましくは20nm以下である。
尚、本明細書において「粒子径」とは、定方向接線径(フェレ径)の平均値(平均粒子径)を意味し、XRD、TEM、SEM法等の公知の手段によって測定することができる。
In the present embodiment, the auxiliary catalyst for the photoanode electrode may have any shape and is not particularly limited, but may be foil-shaped, plate-shaped, particulate, or fine particles. It's okay. In the case of fine particles, the particle size is usually 1 nm or more, preferably 1.2 nm or more, and more preferably 1.5 nm or more because of the ease of supporting the photocatalyst. Further, it is usually 25 nm or less, preferably 20 nm or less.
In the present specification, the "particle diameter" means the average value (average particle diameter) of the tangential wire diameter (ferred diameter) in the directional direction, and can be measured by a known means such as XRD, TEM, SEM method or the like. ..
光アノード電極用助触媒の製造方法としては、一般にはドライプロセスとウェットプロセスがある。ドライプロセスの例としてはスパッタ法、真空蒸着法、CVD法等がある。ウェットプロセスとしては助触媒の前駆体を光触媒に含浸担持した後焼成する含浸法、助
触媒の前駆体を含む溶液に光触媒を浸漬し、これをマイクロウェーブ加熱して担持させるマイクロウェーブ法、助触媒の前駆体を含む溶液に光触媒を浸漬し、これに光を照射して助触媒を析出させる光電着法、助触媒の前駆体を含む溶液に光触媒を浸漬し、これに酸化剤若しくは還元剤を添加して助触媒を析出させるケミカルデポジション法、助触媒の前駆体を含む溶液に電極上に積層した光触媒を浸漬し、これに電位をかけて助触媒を析出させる電析法が例として挙げられる。通常、生産性を考慮すると、助触媒はウェットプロセスで調製されることが好ましい。また、前述の含浸法に類似するが、より均一な組成の粒子を得る観点から、金属の非水溶性錯体の溶液を光触媒に含浸し、これを加水分解して金属酸化物又は金属水酸化物を析出させる手法(以後、「加水分解法」と記載)が好ましい。
As a method for producing a co-catalyst for a photoanode electrode, there are generally a dry process and a wet process. Examples of the dry process include a sputtering method, a vacuum vapor deposition method, and a CVD method. The wet process includes an impregnation method in which the precursor of the co-catalyst is impregnated and supported on the photocatalyst and then fired, a microwave method in which the photocatalyst is immersed in a solution containing the precursor of the co-catalyst and the photocatalyst is heated and supported by microwaves, and the co-catalyst. Photocatalyst is immersed in a solution containing a precursor of Examples include a chemical deposition method in which a co-catalyst is added to precipitate a co-catalyst, and an electrodeposition method in which a photocatalyst laminated on an electrode is immersed in a solution containing a precursor of the co-catalyst and a potential is applied to the photocatalyst to precipitate the co-catalyst. Be done. Generally, in consideration of productivity, it is preferable that the co-catalyst is prepared by a wet process. Further, it is similar to the above-mentioned impregnation method, but from the viewpoint of obtaining particles having a more uniform composition, a solution of a water-insoluble complex of a metal is impregnated into a photocatalyst and hydrolyzed to obtain a metal oxide or a metal hydroxide. (Hereinafter referred to as "hydrolysis method") is preferable.
これらの加水分解法のうち、具体的には、Fe、Ni、Co及びM、を含む非水溶性錯体を基体上に塗布する塗布ステップ、及び基体上に塗布した非水溶性錯体を加水分解する加水分解ステップ、を含む方法が好ましい。
Fe、Ni、Co及びMは、それぞれの成分を含む化合物を溶媒と混合し、必要に応じて撹拌することで、非水溶性錯体を含む塗布液を調製する。
非水溶性錯体は、加水分解中にその塩が水に溶解しない錯体であり、加水分解中の錯体の塩の水に対する溶解度が1%以下であり、0.5%以下であってよく、0.1%以下であってよい。
非水溶性錯体を添加する溶媒は特に限定されないが、有機溶媒であることが好ましく、トルエン又はN−ヘキサンであることがより好ましく、N−ヘキサンであることが更に好ましい。
Among these hydrolysis methods, specifically, a coating step of applying a water-insoluble complex containing Fe, Ni, Co and M on a substrate, and hydrolyzing the water-insoluble complex applied on the substrate. A method comprising a hydrolysis step is preferred.
For Fe, Ni, Co and M, a coating solution containing a water-insoluble complex is prepared by mixing a compound containing each component with a solvent and stirring as necessary.
A water-insoluble complex is a complex whose salt is insoluble in water during hydrolysis, and the solubility of the salt of the hydrolyzed complex in water is 1% or less, may be 0.5% or less, and may be 0. It may be 1% or less.
The solvent to which the water-insoluble complex is added is not particularly limited, but it is preferably an organic solvent, more preferably toluene or N-hexane, and even more preferably N-hexane.
非水溶性錯体は、非水溶性の錯体であれば特に限定されず、典型的には非水溶性の金属錯体であり、有機酸の金属塩であることが好ましい。非水溶性錯体を構成する有機酸としてはカルボン酸が挙げられ、2−エチルヘキサン酸が好ましい。非水溶性錯体を構成する金属としてはFe、Ni、Co、Mn、Kが好ましい。
塗布液中の非水溶性錯体の濃度は特に限定されないが、塗布液としての作業性の観点から100重量ppm以上2000重量ppm以下であることが好ましい。
基体への塗布液の塗布方法は特に限定されず、ドロップキャスト、スプレー塗布、静電塗布、スピンコートのような方法を用いることができる。基体は、非水溶性錯体を保持できればよく、通常は助触媒を担持する光触媒である。
The water-insoluble complex is not particularly limited as long as it is a water-insoluble complex, and is typically a water-insoluble metal complex, preferably a metal salt of an organic acid. Examples of the organic acid constituting the water-insoluble complex include carboxylic acid, and 2-ethylhexanoic acid is preferable. Fe, Ni, Co, Mn, and K are preferable as the metal constituting the water-insoluble complex.
The concentration of the water-insoluble complex in the coating liquid is not particularly limited, but is preferably 100% by weight or more and 2000% by weight or less from the viewpoint of workability as the coating liquid.
The method of applying the coating liquid to the substrate is not particularly limited, and methods such as drop casting, spray coating, electrostatic coating, and spin coating can be used. The substrate is a photocatalyst that carries a co-catalyst, as long as it can hold a water-insoluble complex.
非水溶性錯体の加水分解は、塗布液を塗布した基体を加熱することで行うことができる。加水分解時の平均温度は200℃以下で加熱して行うことが好ましい。非水溶性錯体がアモルファスである場合、200℃以下とすることで非水溶性錯体の結晶構造の変化を押さえることができる。下限は特に限定されないが、通常100℃以上であり、150℃以上であることが好ましい。加熱時間は通常10分以上、好ましくは20分以上であり、また通常1時間以下、好ましくは0.5時間以下である。
なお、加水分解時の平均温度とは、加水分解のための総加熱時間における平均温度である。
Hydrolysis of the water-insoluble complex can be performed by heating the substrate to which the coating liquid is applied. The average temperature during hydrolysis is preferably 200 ° C. or lower. When the water-insoluble complex is amorphous, the change in the crystal structure of the water-insoluble complex can be suppressed by setting the temperature to 200 ° C. or lower. The lower limit is not particularly limited, but is usually 100 ° C. or higher, preferably 150 ° C. or higher. The heating time is usually 10 minutes or more, preferably 20 minutes or more, and usually 1 hour or less, preferably 0.5 hours or less.
The average temperature at the time of hydrolysis is the average temperature in the total heating time for hydrolysis.
本実施形態の、光触媒を含むアノード電極用助触媒は、酸素生成用の助触媒として使用され、光触媒に担持されることで、光アノード電極の酸素生成機能を飛躍的に向上させる。
光触媒として用いられる材料は、Ti、V、Nb及びTaからなる群から選ばれる1種以上の元素を含み、これらの元素のいずれかを含んだ酸化物、酸窒化物、窒化物、(オキシ)カルコゲナイド等が挙げられる。具体的には、TiO2、CaTiO3、SrTiO3、Sr3Ti2O7、Sr4Ti3O7、K2La2Ti3O10、Rb2La2Ti3O10、Cs2La2Ti3O10、CsLaTi2NbO10,La2TiO5、La2Ti3O9、La2Ti2O7、La2Ti2O7:Ba、KaLaZr0.3Ti
0.7O4、La4CaTi5O7、KTiNbO5、Na2Ti6O13、BaTi4O9、Gd2Ti2O7、Y2Ti2O7、(Na2Ti3O7、K2Ti2O5、K2Ti4O9、Cs2Ti2O5、H+−Cs2Ti2O5(H+−CsはCsがH+でイオン交換されていることを示す。以下同様)、Cs2Ti5O11、Cs2Ti6O13、H+−CsTiNbO5、H+−CsTi2NbO7、SiO2−pillared K2Ti4O9、SiO2−pillared K2Ti2.7Mn0.3O7、BaTiO3、BaTi4O9、AgLi1/3Ti2/3O2等のチタン含有酸化物;
LaTiO2N等のチタン含有酸窒化物;及び
La5Ti2CuS5O7、La5Ti2AgS5O7、Sm2Ti2O5S2等のチタン含有(オキシ)カルコゲナイド;等のチタン含有化合物:
BiVO4、Ag3VO4等のバナジウム含有酸化物;等のバナジウム含有化合物:
K4Nb6O17、Rb4Nb6O17、Ca2Nb2O7、Sr2Nb2O7、Ba5Nb4O15、NaCa2Nb3O10、ZnNb2O6、Cs2Nb4O11、La3NbO7、H+−KLaNb2O7、H+−RbLaNb2O7、H+−CsLaNb2O7、H+−KCa2Nb3O10、SiO2−pillared KCa2Nb3O10(Chem.Mater.1996,8,2534.)、H+−RbCa2Nb3O10、H+−CsCa2Nb3O10、H+−KSr2Nb3O10、H+−KCa2NaNb4O13)、PbBi2Nb2O9等のニオブ含有酸化物;及び
CaNbO2N、BaNbO2N、SrNbO2N、LaNbON2等のニオブ含有酸窒化物;等のニオブ含有化合物:
Ta2O5、K2PrTa5O15、K3Ta3Si2O13、K3Ta3B2O12、LiTaO3、NaTaO3、KTaO3、AgTaO3、KTaO3:Zr、NaTaO3:La、NaTaO3:Sr、Na2Ta2O6、K2Ta2O6(pyrochlore)、CaTa2O6、SrTa2O6、BaTa2O6、NiTa2O6、Rb4Ta6O17、H2La2/3Ta2O7、K2Sr1.5Ta3O10、LiCa2Ta3O10、KBa2Ta3O10、Sr5Ta4O15、Ba5Ta4O15、H1.8Sr0.81Bi0.19Ta2O7、Mg−Ta oxide(Chem.Mater.2004 16, 4304−4310)、LaTaO4、La3TaO7等のタンタル含有酸化物;
Ta3N5等のタンタル含有窒化物;及び
CaTaO2N、SrTaO2N、BaTaO2N、LaTaO2N、Y2Ta2O5N2、TaON等のタンタル含有酸窒化物;等のタンタル含有化合物:等が用いられる。
The co-catalyst for an anode electrode including a photocatalyst of the present embodiment is used as an co-catalyst for oxygen generation, and is supported on the photocatalyst to dramatically improve the oxygen generation function of the photoanode electrode.
The material used as a photocatalyst contains one or more elements selected from the group consisting of Ti, V, Nb and Ta, and oxides, oxynitrides, nitrides, (oxy) containing any of these elements. Calcogenides and the like can be mentioned. Specifically, TiO 2 , CaTIO 3 , SrTIO 3 , Sr 3 Ti 2 O 7 , Sr 4 Ti 3 O 7 , K 2 La 2 Ti 3 O 10 , Rb 2 La 2 Ti 3 O 10 , Cs 2 La 2 Ti 3 O 10 , CsLaTi 2 NbO 10 , La 2 TiO 5 , La 2 Ti 3 O 9 , La 2 Ti 2 O 7 , La 2 Ti 2 O 7 : Ba, KaLaZr 0.3 Ti
0.7 O 4 , La 4 CaTi 5 O 7 , KTiNbO 5 , Na 2 Ti 6 O 13 , BaTi 4 O 9 , Gd 2 Ti 2 O 7 , Y 2 Ti 2 O 7 , (Na 2 Ti 3 O 7 ,) K 2 Ti 2 O 5 , K 2 Ti 4 O 9 , Cs 2 Ti 2 O 5 , H + −Cs 2 Ti 2 O 5 (H + −Cs indicates that Cs is ion-exchanged with H +. The same applies hereinafter), Cs 2 Ti 5 O 11 , Cs 2 Ti 6 O 13 , H + -CsTiNbO 5 , H + -CsTi 2 NbO 7 , SiO 2- pillared K 2 Ti 4 O 9 , SiO 2- pillared K 2 Ti 2.7 Mn 0.3 O 7 , BaTiO 3 , BaTi 4 O 9 , AgLi 1/3 Ti 2/3 O 2, etc. Titanium-containing oxides;
Titanium-containing oxynitrides such as LaTIO 2 N; and titanium-containing (oxy) chalcogenides such as La 5 Ti 2 CuS 5 O 7 , La 5 Ti 2 AgS 5 O 7 , Sm 2 Ti 2 O 5 S 2 and the like. Containing compound:
Vanadium-containing oxides such as BiVO 4 , Ag 3 VO 4, etc .; Vanadium-containing compounds such as:
K 4 Nb 6 O 17 , Rb 4 Nb 6 O 17 , Ca 2 Nb 2 O 7 , Sr 2 Nb 2 O 7 , Ba 5 Nb 4 O 15 , NaCa 2 Nb 3 O 10 , ZnNb 2 O 6 , Cs 2 Nb 4 O 11 , La 3 NbO 7 , H + -KLaNb 2 O 7 , H + -RbLaNb 2 O 7 , H + -CsLaNb 2 O 7 , H + -KCa 2 Nb 3 O 10 , SiO 2- pillared KCa 2 3 O 10 (Chem. Mater. 1996, 8, 2534.), H + -RbCa 2 Nb 3 O 10 , H + -CsCa 2 Nb 3 O 10 , H + -KSr 2 Nb 3 O 10 , H + -KCa 2 NaNb 4 O 13 ), niobium-containing oxides such as PbBi 2 Nb 2 O 9 ; and niobium-containing acid nitrides such as CaNbO 2 N, BaNbO 2 N, SrNbO 2 N, LaNbON 2 ; and other niobium-containing compounds:
Ta 2 O 5, K 2 PrTa 5 O 15, K 3 Ta 3 Si 2 O 13, K 3 Ta 3 B 2 O 12, LiTaO 3, NaTaO 3, KTaO 3, AgTaO 3, KTaO 3: Zr, NaTaO 3: La, NaTaO 3 : Sr, Na 2 Ta 2 O 6 , K 2 Ta 2 O 6 (pyrochlore), CaTa 2 O 6 , SrTa 2 O 6 , BaTa 2 O 6 , NiTa 2 O 6 , Rb 4 Ta 6 O 17 , H 2 La 2/3 Ta 2 O 7 , K 2 Sr 1.5 Ta 3 O 10 , LiCa 2 Ta 3 O 10 , KBa 2 Ta 3 O 10 , Sr 5 Ta 4 O 15 , Ba 5 Ta 4 O 15 , H 1.8 Sr 0.81 Bi 0.19 Ta 2 O 7 , Mg-Ta oxide (Chem. Mater. 2004 16, 4304-4310), LaTaO 4 , La 3 TaO 7, and other tantalum-containing oxides;
Tantalum-containing nitrides such as Ta 3 N 5 ; and tantalum-containing oxynitrides such as CaTaO 2 N, SrTaO 2 N, BaTaO 2 N, LaTaO 2 N, Y 2 Ta 2 O 5 N 2 , TaON; etc. Compound: etc. are used.
太陽光を利用した光水分解反応をより効率的に生じさせる観点からは、上記各種光触媒材料のうち、可視光応答型の材料を用いることが好ましい。具体的には、TaON、LaTiO2N、BaTaO2N、SrNbO2Nm、Ta3N5等の金属(酸)窒化物が好ましい。上記の各種光触媒は、固相法、溶液法等の公知の合成方法によって容易に合成可能である。 From the viewpoint of more efficiently causing a photowater decomposition reaction using sunlight, it is preferable to use a visible light responsive material among the above-mentioned various photocatalytic materials. Specifically, metal (acid) nitrides such as TaON, LaTIO 2 N, BaTaO 2 N, SrNbO 2 Nm, and Ta 3 N 5 are preferable. The above-mentioned various photocatalysts can be easily synthesized by a known synthesis method such as a solid phase method or a solution method.
光触媒の形態(形状)については、上記説明した助触媒を担持して光触媒として機能し得るような形態であれば特に限定されるものではない。特に、水分解反応用光アノード電極とする場合は、典型的にはアノード電極上に膜状や箔状で存在すればよく、アノード電極の形状に応じて適宜その形状を設定できる。 The form (shape) of the photocatalyst is not particularly limited as long as it supports the cocatalyst described above and can function as a photocatalyst. In particular, when the photoanode electrode for water splitting reaction is used, it may typically be present on the anode electrode in the form of a film or foil, and the shape can be appropriately set according to the shape of the anode electrode.
光触媒は、上記説明した助触媒に加えて、別の助触媒を共担持させてもよい。例えば、周期表第6族〜第10族から選ばれる1つ以上の元素を含む化合物を助触媒として共担持させることができる。具体的には、酸素生成用助触媒として、Cr、Sb、Nb、Th、Mn、Fe、Co、Ni、Ru、Rh、Irの金属、これらの酸化物又は複合酸化物(ただし、Co及びMnを含む酸化物を除く)が挙げられる。 The photocatalyst may be co-supported with another co-catalyst in addition to the co-catalyst described above. For example, a compound containing one or more elements selected from Groups 6 to 10 of the Periodic Table can be co-supported as a co-catalyst. Specifically, as an oxygen generation co-catalyst, Cr, Sb, Nb, Th, Mn, Fe, Co, Ni, Ru, Rh, Ir metals, oxides or composite oxides thereof (however, Co and Mn). (Excluding oxides containing).
光触媒への助触媒の担持量については、光触媒活性を向上可能な量であれば特に限定されるものではない。例えば、光触媒100質量部に対し、助触媒を0.008質量部以上20.0質量部以下担持することが好ましい。 The amount of the cocatalyst supported on the photocatalyst is not particularly limited as long as it can improve the photocatalyst activity. For example, it is preferable to support 0.008 parts by mass or more and 20.0 parts by mass or less of the co-catalyst with respect to 100 parts by mass of the photocatalyst.
光アノード電極は、典型的には集電極、光触媒層及び助触媒を含み、通常集電極上に光触媒が層状に堆積され、該光触媒には本実施形態の助触媒が担持される。光励起によって生じた電子は集電極へ流れ、一方正孔(ホール)は助触媒へ異動して水を酸化し、酸素を発生させる。
集電極としては、通常導電性の高い金属若しくは透明電極が用いられるが、導電性を有する限り特に限定されない。例えばTa,Ti、Cu、Fe、Ni,Al等が用いられ、集電極が板状の場合には、その厚さが0.1mm以上10mm以下であってよく、0.2mm以上3mm以下であることが好ましい。透明電極としてはFTO、ITOなどが好ましい。
光触媒層としては、上記光触媒材料を用いることができる。板状の集電極上に堆積する場合には、その厚さが50nm以上20μm以下であってよく、500nm以上3μm以下であることが好ましい。
助触媒は、光触媒層に担持されていればよく、光触媒層上に膜状に堆積していてもよく、アイランド状に堆積してもよい。厚さも特に限定されないが、0.1nm以上100nm以下であってよい。
The photoanode electrode typically includes a collector electrode, a photocatalyst layer and a co-catalyst, and usually a photocatalyst is deposited in layers on the photocatalyst, and the photocatalyst carries the co-catalyst of the present embodiment. The electrons generated by photoexcitation flow to the collector electrode, while the holes move to the co-catalyst to oxidize water and generate oxygen.
As the collector electrode, a metal having high conductivity or a transparent electrode is usually used, but it is not particularly limited as long as it has conductivity. For example, when Ta, Ti, Cu, Fe, Ni, Al or the like is used and the collector electrode is plate-shaped, the thickness may be 0.1 mm or more and 10 mm or less, and 0.2 mm or more and 3 mm or less. Is preferable. As the transparent electrode, FTO, ITO and the like are preferable.
As the photocatalyst layer, the above photocatalyst material can be used. When deposited on a plate-shaped collector electrode, the thickness may be 50 nm or more and 20 μm or less, preferably 500 nm or more and 3 μm or less.
The co-catalyst may be supported on the photocatalyst layer, may be deposited in a film shape on the photocatalyst layer, or may be deposited in an island shape. The thickness is not particularly limited, but may be 0.1 nm or more and 100 nm or less.
光アノード電極の対電極となるカソード電極材料としては特に限定されず、例えば水素発生用電極である場合には、Pt、Au、Pd、Cなどがあげられ、Ptを用いることが好ましい。カソード電極に用いられる光触媒としては、CuO、Cu2O、CuBi2O4、CIGS系、WS2、p−Siなどが好ましく例示できる。 The cathode electrode material to be the counter electrode of the optical anode electrode is not particularly limited, and for example, in the case of a hydrogen generating electrode, Pt, Au, Pd, C and the like can be mentioned, and Pt is preferably used. The photocatalyst used for the cathode electrode, CuO, Cu 2 O, CuBi 2 O 4, CIGS -based, WS 2, such as p-Si can be preferably exemplified.
本発明の別の実施形態は、Fe、Ni、Co、M及び酸素、を含むアノード電極用触媒である。上記MはK及びMnから選択される。本実施形態のアノード電極用触媒は、水の電気分解を行う際のアノード電極に担持されることで、水の電気分解反応を加速させる触媒として機能する。上記説明した光アノード電極用助触媒は、水の電気分解の際のアノード電極用触媒としても、使用することができる。 Another embodiment of the present invention is a catalyst for an anode electrode containing Fe, Ni, Co, M and oxygen. The above M is selected from K and Mn. The catalyst for the anode electrode of the present embodiment functions as a catalyst for accelerating the electrolysis reaction of water by being supported on the anode electrode when electrolyzing water. The co-catalyst for the photoanode electrode described above can also be used as a catalyst for the anode electrode during electrolysis of water.
本実施形態に係る水の電気分解の際に用いるアノード電極用触媒は、更に光触媒とともに用いられることで、光により酸素生成が可能な光電極として用いられ得る。光触媒としては、上記説明した光半導体に用いられる化合物を用いることができ、窒化物や酸窒化物であることが好ましい。 The catalyst for the anode electrode used in the electrolysis of water according to the present embodiment can be used as a photoelectrode capable of generating oxygen by light by being further used together with a photocatalyst. As the photocatalyst, the compound used for the photosemiconductor described above can be used, and a nitride or an oxynitride is preferable.
光触媒を実際に水の分解に使用する場合における光触媒の形態については特に限定されるものではない。例えば、水中に光触媒粒子を分散させる形態、光触媒粒子を固めて成形体として当該成形体を水中に設置する形態、基材上に光触媒層を設けて積層体とし当該積層体を水中に設置する形態、集電体上に光触媒を固定化して水電解用電極(光触媒電極)とし対極とともに水中に設置する形態等が挙げられる。特に、光水分解反応を大規模にて行う場合、バイアスを付与して水分解反応を促進できる観点から、水電解用電極とするとよい。上記の成形体とする形態、及び、積層体とする形態においては、当該成形体又は当該積層体はシート状(光触媒シート)であってもよい。 The form of the photocatalyst when the photocatalyst is actually used for decomposing water is not particularly limited. For example, a form in which photocatalyst particles are dispersed in water, a form in which the photocatalyst particles are solidified and the molded body is installed in water as a molded body, a form in which a photocatalyst layer is provided on a base material to form a laminated body, and the laminated body is installed in water. Examples thereof include a form in which a photocatalyst is immobilized on a current collector to form an electrode for water electrolysis (photocatalyst electrode) and installed in water together with a counter electrode. In particular, when the photowater decomposition reaction is carried out on a large scale, it is preferable to use an electrode for water electrolysis from the viewpoint of imparting a bias to promote the water decomposition reaction. In the form of the molded body and the form of the laminated body, the molded body or the laminated body may be in the form of a sheet (photocatalyst sheet).
光アノード電極は公知の方法により作製可能である。例えば、所謂粒子転写法(Chem. Sci., 2013,4, 1120-1124)によって容易に作製可能である。即ち、ガラス等の第1の基材上に光触媒粒子を載せて、光触媒層と第1の基材層との積層体を得る。得られた積層体の光触媒層表面に蒸着等によって導電層(集電体)を設ける。ここで、光触媒層の導電層側表層にある光触媒粒子が導電層に固定化される。その後、導電層表面に第2の基材を接
着し、第1の基材層から導電層及び光触媒層を剥がす。光触媒粒子の一部は導電層の表面に固定化されているので、導電層とともに剥がされ、結果として、光触媒層と導電層と第2の基材層とを有する水電解用電極を得ることができる。
The optical anode electrode can be manufactured by a known method. For example, it can be easily produced by the so-called particle transfer method (Chem. Sci., 2013, 4, 1120-1124). That is, the photocatalyst particles are placed on the first base material such as glass to obtain a laminate of the photocatalyst layer and the first base material layer. A conductive layer (current collector) is provided on the surface of the photocatalyst layer of the obtained laminate by vapor deposition or the like. Here, the photocatalyst particles on the surface layer on the conductive layer side of the photocatalyst layer are immobilized on the conductive layer. After that, the second base material is adhered to the surface of the conductive layer, and the conductive layer and the photocatalyst layer are peeled off from the first base material layer. Since some of the photocatalyst particles are immobilized on the surface of the conductive layer, they are peeled off together with the conductive layer, and as a result, an electrode for water electrolysis having a photocatalyst layer, a conductive layer, and a second base material layer can be obtained. can.
或いは、光触媒粒子が分散されたスラリーを集電体の表面に塗布して乾燥させることで、水電解用電極を得てもよいし、光触媒粒子と集電体とを加圧成形等して一体化することで水電解用電極を得てもよい。また、光触媒粒子が分散されたスラリー中に集電体を浸漬し、電圧を印可して光触媒粒子を電気泳動により集電体上に集積してもよい。
助触媒の担持は、光触媒粒子を集電体上に固定する前に行ってもよいし固定した後であってもよい。例えば、上記した粒子転写法において、助触媒担持前の光触媒を用いて、同様の方法で積層体を得て、その後、光触媒層の表面に助触媒としての複合体を担持させることで、光アノード電極を得てもよい。
Alternatively, an electrode for water electrolysis may be obtained by applying a slurry in which photocatalyst particles are dispersed to the surface of a current collector and drying it, or the photocatalyst particles and the current collector are integrally formed by pressure molding or the like. The electrode for water electrolysis may be obtained by the conversion. Alternatively, the photocatalyst particles may be immersed in the slurry in which the photocatalyst particles are dispersed, and a voltage may be applied to accumulate the photocatalyst particles on the current collector by electrophoresis.
The support of the co-catalyst may be performed before or after the photocatalyst particles are fixed on the current collector. For example, in the above-mentioned particle transfer method, a laminate is obtained by the same method using a photocatalyst before supporting a cocatalyst, and then a composite as a cocatalyst is supported on the surface of the photocatalyst layer to support a photoanode. Electrodes may be obtained.
上述したように、光触媒を水電解用電極に適用する場合、電極性能を向上させる観点から、光触媒において、光触媒100質量部に対して複合体が0.008質量部以上20質量部以下担持されていることが好ましい。或いは、同様の観点から、光触媒の表面の20%以上が当該複合体に覆われてなることが好ましい。光触媒表面における複合体の被覆率は、光触媒粒子を一方向から見た場合における光半導体が占める部分と複合体が占める部分とを、SEM−EDS等によって特定することで算出することができる。例えば、SEM写真図における光半導体部分の面積と複合体部分の面積とを特定し、(複合体部分の面積)/{(光半導体部分の面積)+(複合体部分の面積)}により被覆率を算出することができる。 As described above, when the photocatalyst is applied to the electrode for water electrolysis, from the viewpoint of improving the electrode performance, the photocatalyst is supported with 0.008 parts by mass or more and 20 parts by mass or less of the composite with respect to 100 parts by mass of the photocatalyst. It is preferable to have. Alternatively, from the same viewpoint, it is preferable that 20% or more of the surface of the photocatalyst is covered with the complex. The coverage of the complex on the surface of the photocatalyst can be calculated by specifying the portion occupied by the photosemiconductor and the portion occupied by the complex when the photocatalyst particles are viewed from one direction by SEM-EDS or the like. For example, the area of the optical semiconductor portion and the area of the composite portion in the SEM photograph are specified, and the coverage ratio is determined by (area of the composite portion) / {(area of the optical semiconductor portion) + (area of the composite portion)}. Can be calculated.
本実施形態においては、上記した光触媒、或いは、上記した水電解用電極を、水又は電解質水溶液に浸漬し、当該光触媒又は水電解用電極に光を照射して光水分解を行うことで、水素及び/又は酸素を製造することができる。
例えば、上述のように導電体で構成される集電体上に光触媒を固定化して水電解用電極を得る一方、対極として水素生成触媒を担持した導電体を使用し、液体状又は気体状の水を供給しながら光を照射し、水分解反応を進行させる。必要に応じて外部電力により電極間に電位差を設けることで、水分解反応を促進することができる。或いは、対極として水素生成触媒を担持した光触媒を使用してもよい。この場合、光触媒としては水素生成反応を触媒する公知の光触媒を用いることができる。
In the present embodiment, hydrogen is decomposed by immersing the above-mentioned photocatalyst or the above-mentioned water electrolysis electrode in water or an aqueous electrolyte solution and irradiating the photocatalyst or the water electrolysis electrode with light to perform photowater decomposition. And / or oxygen can be produced.
For example, as described above, a photocatalyst is immobilized on a current collector composed of a conductor to obtain an electrode for water electrolysis, while a conductor carrying a hydrogen generation catalyst is used as a counter electrode, and a liquid or gaseous state is used. Irradiate light while supplying water to allow the water decomposition reaction to proceed. The water splitting reaction can be promoted by providing a potential difference between the electrodes by using external electric power as needed. Alternatively, a photocatalyst carrying a hydrogen production catalyst may be used as a counter electrode. In this case, as the photocatalyst, a known photocatalyst that catalyzes the hydrogen production reaction can be used.
一方、絶縁基材上に光触媒粒子を固定化した固定化物に、又は、光触媒粒子を加圧成形等した成形体に、水を供給しながら光を照射して水分解反応を進行させてもよい。或いは、光触媒粒子を水又は電解質水溶液に分散させて、ここに光を照射して水分解反応を進行させてもよい。この場合、必要に応じて攪拌することで、反応を促進することができる。 On the other hand, the water decomposition reaction may be allowed to proceed by irradiating the immobilized product in which the photocatalyst particles are immobilized on the insulating base material or the molded body in which the photocatalyst particles are pressure-molded with water while supplying water. .. Alternatively, the photocatalyst particles may be dispersed in water or an aqueous electrolyte solution and irradiated with light to allow the water splitting reaction to proceed. In this case, the reaction can be promoted by stirring as necessary.
以下に、実施例により本発明を更に詳細に説明するが、本発明の範囲が実施例のみに限定されないことはいうまでもない。 Hereinafter, the present invention will be described in more detail by way of examples, but it goes without saying that the scope of the present invention is not limited to the examples.
(実施例1〜5、比較例1)
下記式(1)で表されるトリス(2−エチルヘキサン酸)鉄(III)・ミネラルスピリット溶液(Fe:6%)(富士フイルム和光純薬)、下記式(2)で表される2−エチルヘキサン酸ニッケル(II)トルエン溶液(Ni:6%)(富士フイルム和光純薬)、下記式(3)で表される2−エチルヘキサン酸コバルト(II)・ミネラルスピリット溶液(Co:12%)(富士フイルム和光純薬)、下記式(4)で表される2−エチルヘキサン酸カリウム溶液(K:75%)(富士フイルム和光純薬)、下記式(5)で表される2−エチルヘキサン酸マンガン(II)・ミネラルスピリット溶液(Mn:8%)(富士
フイルム和光純薬)を個別にヘキサン(富士フイルム和光純薬)と混合し、各元素濃度が1.2重量%である5つの原料溶液を調製した。
(Examples 1 to 5, Comparative Example 1)
Tris (2-ethylhexanoic acid) iron (III) / mineral spirit solution (Fe: 6%) (Fujifilm Wako Pure Chemical Industries, Ltd.) represented by the following formula (1), 2-represented by the following formula (2) Nickel (II) ethylhexanoate toluene solution (Ni: 6%) (Fujifilm Wako Pure Chemical Industries, Ltd.), 2-ethylhexanoate cobalt (II) mineral spirit solution (Co: 12%) represented by the following formula (3) ) (Fujifilm Wako Pure Chemical Industries, Ltd.), 2-ethylhexanoate potassium solution (K: 75%) (Fujifilm Wako Pure Chemical Industries, Ltd.) represented by the following formula (4), 2-represented by the following formula (5) Manganese (II) ethylhexanoate / mineral spirit solution (Mn: 8%) (Fujifilm Wako Pure Chemical Industries, Ltd.) is individually mixed with hexane (Fujifilm Wako Pure Chemical Industries, Ltd.), and the concentration of each element is 1.2% by weight. Five raw material solutions were prepared.
原料溶液を混合しヘキサンにて希釈して元素の組成を表1のように変えたアノード電極用触媒前駆体溶液30μLを、洗浄乾燥した1.2cm×2cm角のフッ素ドープ酸化スズ(FTO)導電性ガラス基板(日本板硝子)にマイクロピペットを用いて滴下した。自然乾燥後、140℃の乾燥機内に0.5時間保持し熱処理を行った。これらを実施例1〜5及び、比較例1のアノード電極とした。 30 μL of the catalyst precursor solution for the anode electrode, which was obtained by mixing the raw material solution and diluting with hexane to change the element composition as shown in Table 1, was washed and dried to obtain 1.2 cm × 2 cm square fluorine-doped tin oxide (FTO) conductivity. The solution was dropped onto a sex glass substrate (Nippon Sheet Glass) using a micropipette. After natural drying, it was kept in a dryer at 140 ° C. for 0.5 hours for heat treatment. These were used as the anode electrodes of Examples 1 to 5 and Comparative Example 1.
K2HPO4及びKOH(富士フイルム和光純薬)をイオン交換水に溶解し、pHメーター(東亜ディーケーケー、GST−2729C)を用いてpH13に調整した0.5MのK2HPO4電解質水溶液100mLを調製した。作製したアノード電極を電解質溶液中に入れ、Ag/AgCl参照極(ビー・エー・エス、RE−1B)、及びPt線対極を用いた三電極方式にて電気化学測定を行った。ポテンショスタット/ガルバノスタット装置(イーシーフロンティア、ECstat−301)を用い、−0.2〜+1V(vs.Ag/AgCl)の範囲を速度50mV/sにて掃引し、ダーク電流を評価した。ポテンシャルの可逆水素電極(RHE)への補正は次式で行った:
ポテンシャル(vs.RHE)=ポテンシャル(vs.Ag/AgCl)+0.195V+0.059pH
表1に1.8V−RHEでの電流密度の測定結果を示した。
K 2 HPO 4 and KOH (Fujifilm Wako Pure Chemical Industries, Ltd.) were dissolved in ion-exchanged water, and 100 mL of 0.5 M K 2 HPO 4 electrolyte aqueous solution adjusted to pH 13 using a pH meter (DKK-TOA, GST-2729C) was added. Prepared. The prepared anode electrode was placed in an electrolyte solution, and electrochemical measurement was performed by a three-electrode method using an Ag / AgCl reference electrode (BS, RE-1B) and a Pt wire counter electrode. Using a potentiostat / galvanostat device (EC frontier, ECstat-301), a range of −0.2 to + 1V (vs. Ag / AgCl) was swept at a speed of 50 mV / s to evaluate dark current. The correction of the potential to the reversible hydrogen electrode (RHE) was performed by the following equation:
Potential (vs. RHE) = Potential (vs. Ag / AgCl) + 0.195 V + 0.059 pH
Table 1 shows the measurement results of the current density at 1.8V-RHE.
表1から明らかなように、Fe、Ni及びCoと、第4の成分としてK又はMnとを選択した場合は、比較例に比べ顕著に大きな電流密度の値を示した。 As is clear from Table 1, when Fe, Ni and Co and K or Mn as the fourth component were selected, the values of the current densities were significantly larger than those of the comparative example.
(実施例6〜9、比較例2)
Taメタル基板上に成膜したTa3N5光電極を、既報(Angewandte Chemie International Edition、第56巻、17号、4739〜4743頁、2017年)に記載の方法に準じて作製した。
実施例1〜5で用いた1.2重量%濃度の5つの原料溶液を混合し、ヘキサンにて希釈して元素の組成を表2のように変えた助触媒前駆体溶液を準備し、15μLを、1×1cm2角のTa3N5光電極へ滴下した。自然乾燥後、140℃の乾燥機内に0.5時間保持し熱処理を行った。これらを実施例6〜9、及び比較例2の光アノード電極とした。
(Examples 6 to 9, Comparative Example 2)
A Ta 3 N 5 optical electrode formed on a Ta metal substrate was produced according to the method described in a previous report (Angewandte Chemie International Edition, Vol. 56, No. 17, pp. 4739-4743, 2017).
Five raw material solutions having a 1.2% by mass concentration used in Examples 1 to 5 were mixed and diluted with hexane to prepare a co-catalyst precursor solution in which the composition of the elements was changed as shown in Table 2, and 15 μL was prepared. Was dropped onto a 1 × 1 cm 2 square Ta 3 N 5 optical electrode. After natural drying, it was kept in a dryer at 140 ° C. for 0.5 hours for heat treatment. These were used as the photoanode electrodes of Examples 6 to 9 and Comparative Example 2.
インジウム(ニラコ)を用いて機器配線用ジュンフロン電線(潤工社、AF04A050)と接続し、アラルダイト(ニチバン、AR−R30)で接続部及び裏面を被覆した。画像解析により算出した助触媒担持Ta3N5光電極の露出面積は0.4〜0.6cm2であった。 It was connected to a Junflon electric wire for equipment wiring (Junko Co., Ltd., AF04A050) using indium (Niraco), and the connection portion and the back surface were covered with Araldite (Nichiban, AR-R30). The exposed area of the co-catalyst-supported Ta 3 N 5 photoelectrode calculated by image analysis was 0.4 to 0.6 cm 2 .
K2HPO4及びKOH(富士フイルム和光純薬)をイオン交換水に溶解し、pHメーター(東亜ディーケーケー、GST−2729C)を用いてpH13に調整した0.5MのK2HPO4電解質水溶液150mLを調製した。作製した助触媒担持Ta3N5光電極を電解質水溶液中に入れ、Ag/AgCl参照極(ビー・エー・エス、RE−1B)、及びPt線対極を用いた三電極方式にて光電気化学測定を行った。電気化学アナライザー(ビー・エー・エス、ALSモデル627E)を用い、−0.9〜+0.35V(vs.Ag/AgCl)の範囲を速度10mV/sにて掃引し、アノード電流を評価した。ポテンシャルの可逆水素電極(RHE)への補正は次式で行った:
ポテンシャル(vs.RHE)=ポテンシャル(vs.Ag/AgCl)+0.195V+0.059pH
ラジオメーターを用いてAM1.5に調整されたソーラーシミュレータ(三永電機製作所、XES−40S3)を光源とし、3s毎の光オンオフ切り替えにより光応答電流を評価した。表2に1.29V−RHEでの電流密度の測定結果を示した。
K 2 HPO 4 and KOH (Fujifilm Wako Pure Chemical Industries, Ltd.) were dissolved in ion-exchanged water, and 150 mL of 0.5 M K 2 HPO 4 electrolyte aqueous solution adjusted to pH 13 using a pH meter (DKK-TOA, GST-2729C) was added. Prepared. The prepared co-catalyst-supported Ta 3 N 5 photoelectrode was placed in an aqueous electrolyte solution, and photoelectrochemistry was performed by a three-electrode method using an Ag / AgCl reference electrode (BS, RE-1B) and a Pt line counter electrode. Measurements were made. Using an electrochemical analyzer (BAS, ALS model 627E), the range of −0.9 to +0.35 V (vs. Ag / AgCl) was swept at a speed of 10 mV / s to evaluate the anode current. The correction of the potential to the reversible hydrogen electrode (RHE) was performed by the following equation:
Potential (vs. RHE) = Potential (vs. Ag / AgCl) + 0.195 V + 0.059 pH
Using a solar simulator (Sanaga Denki Seisakusho, XES-40S3) adjusted to AM1.5 using a radiometer as a light source, the optical response current was evaluated by switching the optical on / off every 3 seconds. Table 2 shows the measurement results of the current density at 1.29V-RHE.
表2から明らかなように、Fe、Ni、Coと、第4の成分としてK及びMnとを選択した場合、比較例に比べ顕著に大きな電流密度の値を示し、本実施形態の光アノード用助触媒によって、Ta3N5光電極の性能が向上したことがわかる。 As is clear from Table 2, when Fe, Ni, Co and K and Mn are selected as the fourth component, the values of the current densities are significantly larger than those of the comparative example, and the optical anode of the present embodiment is used. It can be seen that the co-catalyst improved the performance of the Ta 3 N 5 photoelectrode.
Claims (7)
但し前記MはK及びMnから選択される。 A catalyst for an anode electrode containing Fe, Ni, Co, M and oxygen.
However, the M is selected from K and Mn.
但し前記MはK及びMnから選択される。 A co-catalyst for a photoanode electrode containing Fe, Ni, Co, M and oxygen.
However, the M is selected from K and Mn.
但し前記MはK及びMnから選択される。 A catalyst for an anode electrode or a catalyst for an anode electrode, which comprises a coating step of applying a water-insoluble complex containing Fe, Ni, Co, and M on a substrate and a hydrolysis step of hydrolyzing the water-insoluble complex coated on the substrate. A method for producing a co-catalyst for an optical anode electrode.
However, the M is selected from K and Mn.
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