JP4915719B2 - ZnS-CuX solid solution photocatalyst exhibiting high activity in hydrogen production from aqueous solution containing sulfur compound under sunlight irradiation - Google Patents
ZnS-CuX solid solution photocatalyst exhibiting high activity in hydrogen production from aqueous solution containing sulfur compound under sunlight irradiation Download PDFInfo
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- 239000006104 solid solution Substances 0.000 title claims description 58
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims description 47
- 229910052739 hydrogen Inorganic materials 0.000 title claims description 46
- 239000001257 hydrogen Substances 0.000 title claims description 46
- 230000000694 effects Effects 0.000 title claims description 40
- 239000011941 photocatalyst Substances 0.000 title claims description 35
- 150000003464 sulfur compounds Chemical class 0.000 title claims description 6
- 238000004519 manufacturing process Methods 0.000 title description 15
- 239000007864 aqueous solution Substances 0.000 title description 13
- 230000001747 exhibiting effect Effects 0.000 title description 5
- 239000003638 chemical reducing agent Substances 0.000 claims description 8
- 229910052984 zinc sulfide Inorganic materials 0.000 claims description 8
- 229910021591 Copper(I) chloride Inorganic materials 0.000 claims description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 6
- 239000013078 crystal Substances 0.000 claims description 6
- 229910052760 oxygen Inorganic materials 0.000 claims description 6
- 239000001301 oxygen Substances 0.000 claims description 6
- 229910021589 Copper(I) bromide Inorganic materials 0.000 claims description 5
- 238000000354 decomposition reaction Methods 0.000 claims description 5
- 238000001228 spectrum Methods 0.000 claims description 5
- WGPCGCOKHWGKJJ-UHFFFAOYSA-N sulfanylidenezinc Chemical compound [Zn]=S WGPCGCOKHWGKJJ-UHFFFAOYSA-N 0.000 claims description 4
- 229910052736 halogen Inorganic materials 0.000 claims description 2
- 125000005843 halogen group Chemical group 0.000 claims description 2
- 238000001354 calcination Methods 0.000 claims 1
- OXBLHERUFWYNTN-UHFFFAOYSA-M copper(I) chloride Chemical group [Cu]Cl OXBLHERUFWYNTN-UHFFFAOYSA-M 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 description 31
- 239000010949 copper Substances 0.000 description 26
- 239000003054 catalyst Substances 0.000 description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- 238000006862 quantum yield reaction Methods 0.000 description 12
- 239000011701 zinc Substances 0.000 description 12
- 239000000243 solution Substances 0.000 description 9
- 238000010438 heat treatment Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- OMZSGWSJDCOLKM-UHFFFAOYSA-N copper(II) sulfide Chemical compound [S-2].[Cu+2] OMZSGWSJDCOLKM-UHFFFAOYSA-N 0.000 description 7
- 238000005259 measurement Methods 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 6
- 230000001699 photocatalysis Effects 0.000 description 5
- 238000010521 absorption reaction Methods 0.000 description 4
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- 238000000695 excitation spectrum Methods 0.000 description 4
- 239000010453 quartz Substances 0.000 description 4
- 238000000985 reflectance spectrum Methods 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
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- 238000000034 method Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 241000511976 Hoya Species 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910002367 SrTiO Inorganic materials 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 238000000295 emission spectrum Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 238000004817 gas chromatography Methods 0.000 description 2
- 230000001678 irradiating effect Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910000510 noble metal Inorganic materials 0.000 description 2
- 238000006303 photolysis reaction Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000001308 synthesis method Methods 0.000 description 2
- RZVAJINKPMORJF-UHFFFAOYSA-N Acetaminophen Chemical compound CC(=O)NC1=CC=C(O)C=C1 RZVAJINKPMORJF-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 229910003071 TaON Inorganic materials 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- DVRDHUBQLOKMHZ-UHFFFAOYSA-N chalcopyrite Chemical group [S-2].[S-2].[Fe+2].[Cu+2] DVRDHUBQLOKMHZ-UHFFFAOYSA-N 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
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- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
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- 239000012535 impurity Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 238000013032 photocatalytic reaction Methods 0.000 description 1
- 230000015843 photosynthesis, light reaction Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000005297 pyrex Substances 0.000 description 1
- 238000011002 quantification Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 230000004043 responsiveness Effects 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 238000003746 solid phase reaction Methods 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000000629 steam reforming Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000005486 sulfidation Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 229910001428 transition metal ion Inorganic materials 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
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Description
本発明は、助触媒未担持でも疑似太陽光照射下で、還元剤である硫黄化合物、例えばＳ２−とＳＯ３ ２−イオンを含む化合物の水溶液からの水素生成反応において、助触媒未担持の条件で、ＣｄＳ光触媒や本発明者らが報告したＣｕドーピングＺｎＳ光触媒よりも高い活性を示すＺｎＳとＣｕＸ、特にＸはＣｌ又は／及びＢｒである、との固溶体からなる光触媒に関する。 In the hydrogen generation reaction from an aqueous solution of a sulfur compound that is a reducing agent, for example, a compound containing S 2− and SO 3 2− ions under pseudo sunlight irradiation even when the promoter is not supported, the promoter is not supported. The present invention relates to a photocatalyst composed of a solid solution of ZnS and CuX exhibiting higher activity than the CdS photocatalyst and the Cu-doped ZnS photocatalyst reported by the present inventors, in particular, X is Cl or / and Br.
化石資源は無尽蔵とは言えないことから、これらを化学原料など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。前記のような環境問題を引き起こさないエネルギーへの変換が取りざたされるなかで、光触媒を用いた水の分解反応は、太陽光を利用して、水を水素と酸素に分解する水素製造のためのクリーンなエネルギーシステムとして期待されている。そして、次世代エネルギー源として水素の利用に大きな注目が集まっている。また、水素をエネルギー源とする、エネルギー変換のための手段として、水素用燃料電池の研究開発や水素を社会や暮らしに取り入れるためのシステムや施設の検討が精力的に行われている。しかしながら、効率的な水素の製造には、現在のところ二酸化炭素の排出を伴う化石燃料に大きく依存しており、高効率な水蒸気改質技術や燃料電池の開発も根本的な環境問題を解決するまでには至っていない。
前記光触媒を用いた水の分解反応は、太陽光を利用して、水を水素と酸素に分解する水素製造のための実用的なクリーンなエネルギーシステムを構築するものとして期待されている。
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. While the conversion to energy that does not cause environmental problems as described above has been pursued, the water decomposition reaction using a photocatalyst is for the production of hydrogen that uses sunlight to decompose water into hydrogen and oxygen. Expected to be a clean energy system. And much attention has been focused on the use of hydrogen as a next-generation energy source. In addition, as a means for energy conversion using hydrogen as an energy source, research and development of hydrogen fuel cells and studies of systems and facilities for incorporating hydrogen into society and daily life have been vigorously conducted. However, efficient hydrogen production currently relies heavily on fossil fuels with carbon dioxide emissions, and the development of highly efficient steam reforming technologies and fuel cells also solves the fundamental environmental problems. It has not yet reached.
The water decomposition reaction using the photocatalyst is expected to construct a practical clean energy system for hydrogen production using sunlight to decompose water into hydrogen and oxygen.
一方、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から、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可視光応答性光触媒の開発が不可欠である。これまでに、紫外光照射下であれば水を水素と酸素に分解できる高効率な光触媒がいくつか見出されている（非特許文献１−３）。可視光照射下においては，効率は現在のところ低いが、ＧａＮ：ＺｎＳ固溶体（非特許文献４）や水素または酸素生成の半反応に活性を示す光触媒を組み合わせたＩＯ３−／Ｉ−レドックスＰｔ／ＳｒＴｉＯ３：Ｃｒ、Ｔａ−Ｐｔ／Ｗ０３、Ｐｔ／ＴａＯＮ：Ｐｔ／ＷＯ３や Ｆｅ３＋／Ｆｅ２＋レドックスＰｔ／ＳｒＴｉＯ３：Ｒｈ−ＢｉＶＯ４などのＺスキーム系により水の完全分解が成功している（非特許文献５−８、特許文献１）。
このような中で、本発明者のグループは，犠牲試薬としてＳ２−やＳＯ３ ２−などの還元剤を用いた水からの水素生成、すなわち水分解の半反応において、可視光照射下で高活性を示す硫化物光触媒の開発をおこなっている（非特許文献９−１０）。また、ＮｉやＣｕなどの遷移金属イオンをドーピングしたＺｎＳは、これらの金属によるバンド構造の変化により、Ｐｔのような貴金属助触媒が未担持でも可視光照射下で高活性を示すことを報告している（非特許文献１１）。更に、カルコパイライト構造のＡｇＧａＳ２はＲｈを担持することで，量子収率２５％(波長：４４０ｎｍ)の高活性が得られることが報告している（特許文献２）。更に、ＺｎＳとＣｕＩｎＳ２、ＡｇＩｎＳ２との固溶体光触媒においては、Ｒｕを助触媒として担持した（ＣｕＡｇ）１５Ｉｎ０．３Ｚｎ１．５５Ｓ２固溶体光触媒が疑似太陽光照射下においても水素生成反応において高い活性（見掛けの量子収率及び水素発生速度の特性において。）示すことを報告している（非特許文献１２−１４、特許文献３）。
On the other hand, almost 95% or more of sunlight is in the visible light and longer wavelength region, so visible light responsiveness is necessary for the construction of a new energy system that effectively utilizes sunlight energy to decompose water. Development of photocatalyst is essential. So far, several highly efficient photocatalysts that can decompose water into hydrogen and oxygen under ultraviolet light irradiation have been found (Non-Patent Documents 1-3). Under visible light irradiation, the efficiency is currently low, but IO 3 − / I - redox Pt / combined with a GaN: ZnS solid solution (Non-Patent Document 4) and a photocatalyst exhibiting activity in the half reaction of hydrogen or oxygen generation. SrTiO 3 : Cr, Ta—Pt / W0 3 , Pt / TaON: Pt / WO 3 and Fe 3+ /
Under such circumstances, the group of the present inventor is able to generate hydrogen from water using a reducing agent such as S 2− or SO 3 2− as a sacrificial reagent, that is, in the half reaction of water splitting under visible light irradiation. A sulfide photocatalyst exhibiting high activity is being developed (Non-patent Documents 9-10). In addition, ZnS doped with transition metal ions such as Ni and Cu has been reported to show high activity under visible light irradiation even when a noble metal promoter such as Pt is not supported, due to changes in the band structure caused by these metals. (Non-Patent Document 11). Furthermore, it has been reported that AgGaS 2 having a chalcopyrite structure can obtain a high activity with a quantum yield of 25% (wavelength: 440 nm) by carrying Rh (Patent Document 2). Furthermore, in the solid solution photocatalyst of ZnS, CuInS 2 , and AgInS 2 , the (CuAg) 15 In 0.3 Zn 1.55 S 2 solid solution photocatalyst supported with Ru as a cocatalyst is capable of generating hydrogen even under simulated sunlight irradiation. Have high activity (in terms of the characteristics of the apparent quantum yield and hydrogen generation rate) (Non-patent Documents 12-14 and Patent Document 3).
本発明の課題は、基本的には、助触媒なしにおいてもより活性な水素生成反応を示し、長波長の可視光で水分解活性を有するＺｎＳを用いた光触媒を提供することである。そこでＺｎＳとＣｕＸとの固溶体を、前記原料の調製と焼成温度（６７３Ｋ〜８７３Ｋ）などを工夫して作製し、合成条件と得られた固溶体の特定（粉末Ｘ線パターン）、走査電子顕微鏡像）と光触媒活性を検討し、基本的な結晶構造がZinc blende型の結晶構造である、ＺｎＳとＣｕＣｌやＣｕＢｒとのヘテロ固溶体を形成することで、Ｃｕ３ｄ軌道が価電子帯の形成に関与することにより、硫黄化合物を犠牲薬とする水素生成光触媒活性の高い光触媒が得られることを発見し、前記課題を解決することができた。 An object of the present invention is basically to provide a photocatalyst using ZnS which exhibits a more active hydrogen generation reaction without a cocatalyst and has water splitting activity with visible light having a long wavelength. Therefore, a solid solution of ZnS and CuX was prepared by devising the preparation of the raw materials and the firing temperature (673K to 873K), etc., and synthesis conditions and identification of the obtained solid solution (powder X-ray pattern), scanning electron microscope image) And the photocatalytic activity, and the formation of a heterosolid solution of ZnS and CuCl or CuBr, whose basic crystal structure is a Zinc blende type crystal structure, the Cu3d orbital is involved in the formation of the valence band. The present inventors have found that a photocatalyst having a high hydrogen-producing photocatalytic activity using a sulfur compound as a sacrificial agent can be obtained, thereby solving the above problems.
本発明は、（１）（ＺｎＳ）１−Ｙ（ＣｕＸ）Ｙ（ここでＹは０．０１≦Ｙ≦０．２、好ましくは０．０５≦Ｙ≦０．２であり、Ｘはハロゲン元素である）の組成の太陽光照射下で還元剤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固溶体からなる光触媒である。好ましくは、（２）固溶体の結晶構造が基本的にはZinc blende型である前記（１）に記載の光触媒であり、より好ましくは、（３）固溶体がＺｎＳとして酸素存在下（空気）において４００℃±１００℃において２±１時間焼成しＸＲＤスペクトルにおいてＺｎＯ及びＺｎＳＯ４に帰属するピークが見られないものを用いＣｕＸと混合し６７３Ｋ〜８７３Ｋの範囲で焼成することにより得られたものである前記（１）又は（２）に記載の光触媒である。また、本発明は（４）
ＣｕＸがＣｕＣｌおよび／又はＣｕＢｒであり還元剤が硫黄化合物である前記（１）、（２）及び（３）に記載の固溶体からなる光触媒である。
In the present invention, (1) (ZnS) 1-Y (CuX) Y (where Y is 0.01 ≦ Y ≦ 0.2, preferably 0.05 ≦ Y ≦ 0.2, and X is a halogen element. The photocatalyst is composed of a solid solution having an activity of generating hydrogen by photo-water decomposition of an aqueous solution containing a reducing agent under irradiation with sunlight having a composition of Preferably, (2) the photocatalyst according to (1) above, wherein the solid solution has a Zinc blende type crystal structure, and more preferably (3) the solid solution is 400 as ZnS in the presence of oxygen (air). It is obtained by baking at ± 100 ° C. for 2 ± 1 hour, mixing with CuX using a powder in which no peaks attributed to ZnO and
A photocatalyst comprising the solid solution according to (1), (2) and (3), wherein CuX is CuCl and / or CuBr and the reducing agent is a sulfur compound.
発明の効果として、助触媒未担持において疑似太陽光照射下において、安定で４５０ｎｍ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。 As an effect of the invention, it is possible to construct a photodecomposition hydrogen generation catalyst system of water that can stably use visible light in a wide wavelength range up to 450 nm under pseudo-sunlight irradiation with no promoter supported.
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
４）発光測定；蛍光強度計（Spex;Fluorolog）
５）走査電子顕微鏡；JEOL；JSW-7400F
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、０．２５Ｍ Ｋ２ＳＯ３＋ 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）太陽光シミュレーター（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。）
６）みかけの量子収率（ＱＹ）（％）の測定には、前記Ｃｕｔ−ｏｆｆフィルター(HOYA)とｂａｎｄ−ｐａｓｓフィルター（Ｋｅｎｋｏ）により単色光を照射して行った。光量測定は，フォトダイオード（ＯＰＨＩＲ；ａ ＰＤ３００−ＵＶ ＳＨ ｈｅａｄ ａｎｄ ａ ＮＯＶＡ ｅｎｅｒｇｙ ｍｏｎｉｔｏｒ）を用いて行った。
なおＱＹ（％）は、
ＱＹ＝｛（生成物の生成に要した電指数又は正孔数）／（入射光子数）｝×１００
で算出される。
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. 4) Luminescence measurement; Fluorescence intensity meter (Spex; Fluorolog)
5) Scanning electron microscope; JEOL; JSW-7400F
B. 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. In mixed aqueous solution (0.5 M K 2 SO 3 +0.1 M Na 2 S or 0.25 M K 2 SO 3 + 0.35 M 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.)
6) The apparent quantum yield (QY) (%) was measured by irradiating monochromatic light with the cut-off filter (HOYA) and the band-pass filter (Kenko). The light quantity was measured using a photodiode (OPHIR; a PD300-UV SH head and a NOVA energy monitor).
QY (%) is
QY = {(electric exponent or number of holes required for production of product) / (number of incident photons)} × 100
Is calculated by
Ａ．ＺｎＳ−ＣｕＣｌ固溶体：（ＺｎＳ）１−Ｙ（ＣｕＣｌ）Ｙ（ここでＹは０．０１≦Ｙ≦０．２０である）の合成；
（１）ＣｕＣｌは、ＣｕＣｌ２とＣｕ金属片を含む塩酸水溶液を熱して合成した。
（２）ＺｎＳ（Ｋｏｊｕｎｄｏ）は空気中において４００℃で１−３時間焼成処理したＸＤＲからＺｎＯやＺｎＳＯ４に帰属するピークが観察されないものを用いた。
（３）前記合成した原料を混練し、石英アンプルに入れ６７３Ｋ−８７３Ｋで熱処理することによりＺｎＳ−ＣｕＣｌ固溶体を得た。
この工程において、混練時間はＣｕＣｌが硫化されない程度の長さ（色が茶色くならない程度に混錬：見た目で判断）とすることにより光触媒活性の良い固溶体が得られた。前記（２）の処理も混練時のＣｕＣｌの硫化を進めないために重要なファクターである。
Ｂ．ＺｎＳ−ＣｕＢｒ固溶体の合成；
前記ＺｎＳ−ＣｕＣｌ固溶体の場合と同様の方法により合成できる。
A. Synthesis of ZnS—CuCl solid solution: (ZnS) 1-Y (CuCl) Y (where Y is 0.01 ≦ Y ≦ 0.20);
(1) CuCl was synthesized by heating an aqueous hydrochloric acid solution containing CuCl 2 and Cu metal pieces.
(2) ZnS (Kojundo) was used in which no peaks attributed to ZnO or ZnSO 4 were observed from XDR fired at 400 ° C. for 1-3 hours in air.
(3) The synthesized raw materials were kneaded, put into a quartz ampule, and heat-treated at 673K-873K to obtain a ZnS-CuCl solid solution.
In this step, the kneading time was set to such a length that CuCl was not sulfided (kneading to such an extent that the color did not turn brown: judged by appearance), whereby a solid solution with good photocatalytic activity was obtained. The treatment (2) is also an important factor for preventing CuCl sulfidation during kneading.
B. Synthesis of ZnS-CuBr solid solution;
It can be synthesized by the same method as in the case of the ZnS-CuCl solid solution.
Ｃ．比較サンプルとして、
１）ＺｎＳとＣｕＳまたはＣｕ２Ｓとの固相反応により得られたＺｎ１−ＹＣｕＹＳ、
２）前記非特許文献９に記載のＣｕドーピングＺｎＳ合成方法、すなわち、Ｚｎ（ＮＯ３）２とＣｕ（ＮＯ３）２の混合水溶液中に、Ｎａ２Ｓ水溶液を添加して沈澱を得た後、その状態で15時間程度撹拌・熟成した。得られたペースト状の沈殿物を純水を用いて洗浄し、乾燥せずに光触媒「Ｃｕ（４．５ｍｏｌ％）光触媒」とした。及び
３）ＣｄＳ触媒；高純度化学から購入したＣｄＳを石英アンプル中で１０２３Ｋで熱処理し、Wurtzite型としたもの。
C. As a comparative sample,
1) Zn 1-Y Cu Y S obtained by solid phase reaction between ZnS and CuS or Cu 2 S,
2) Cu doping ZnS synthesis method described in
試料の特性；
図２及び図３に（ＺｎＳ）１−Ｙ（ＣｕＣｌ）Ｙ（Ｙ＝０．０１−０．２）の固溶体（ｂ−ｆ）、ＺｎＳ（ａ）、ＣｕＣｌ（ｇ）、Ｃｕ２Ｓから合成したＺｎ０．９Ｃｕ０．１Ｓの触媒（ｈ）、及びＣｕＳから合成したＺｎ０．９Ｃｕ０．１Ｓの触媒（ｉ）の粉末Ｘ線回折パターン（図２）及び拡散反射スペクトル（図３）を示す。これらの試料は段落〔００１０〕で説明した合成法に従って作製した。得られた（ＺｎＳ）１−Ｙ（ＣｕＣｌ）Ｙ固溶体の回折パターンは、２８．７度および４７．７度付近に特徴的なピークを示しており、得られた試料の結晶構造はＺｎＳやＣｕＣｌと同じZinc blende型であることがわかった。わずかにWurtziteの結晶相が現れているサンプルもあった。Ｙ＝０．０１以外の固溶体は，不純物として不定比のＣｕＹＳ（▽印）が確認され固溶量の増加に伴いそのピーク強度は大きくなっていた。しかし、このＣｕＹＳのＺｎＳに対するピーク比は非常に小さく、ほとんどのＣｕＣｌはＺｎＳとの固溶体を形成していると考えられる。（ＺｎＳ）１−Ｙ（ＣｕＣｌ）Ｙ固溶体は，結晶性が良く、同じ固溶量で比較した場合、（ＺｎＳ）０．９（ＣｕＣｌ）０．１はＣｕＳやＣｕ２Ｓから合成したＺｎ０．９Ｃｕ０．１Ｓ固溶体よりも半値幅が狭くなっていた。これはＣｕＣｌがフラックスとして働いているためだと考えられる。図３の固溶体の拡散反射スペクトルは、（ａ）ＺｎＳおよび（ｇ）ＣｕＣｌは４００ｎｍ以下の紫外光しか吸収を示さないが、ＺｎＳとＣｕＣｌとを固溶することで可視光領域まで吸収を示した。 （ＺｎＳ）０．９（ＣｕＣｌ）０．１、（ＺｎＳ）０．８５ＣｕＣｌ）０．１５、（ＺｎＳ）０．８（ＣｕＣｌ）０．２は可視光領域にはっきりとした吸収端を持つスペクトルとなった。Ｚｎ０．９Ｃｕ０．１Ｓ固溶体のスペクトル（ｈ）（ｉ）は、ＺｎＳ基礎吸収から可視光領域に裾がのびたブロードなスペクトルとなり、同じＣｕの固溶量の（ＺｎＳ）０．９（ＣｕＣｌ）０．１とは異なっていた。
Sample characteristics;
FIG. 2 and FIG. 3 are synthesized from (ZnS) 1-Y (CuCl) Y (Y = 0.01-0.2) solid solution (bf), ZnS (a), CuCl (g), and Cu 2 S. X-ray diffraction pattern (FIG. 2) and diffuse reflectance spectrum of Zn 0.9 Cu 0.1 S catalyst (h) and Zn 0.9 Cu 0.1 S catalyst (i) synthesized from CuS ( FIG. 3) is shown. These samples were prepared according to the synthesis method described in paragraph [0010]. The diffraction pattern of the obtained (ZnS) 1-Y (CuCl) Y solid solution shows characteristic peaks around 28.7 degrees and 47.7 degrees, and the crystal structure of the obtained sample is ZnS or CuCl. The same Zinc blende type was found. Some samples showed a slight Wurtzite crystal phase. In solid solutions other than Y = 0.01, non-stoichiometric Cu Y S (（) was confirmed as an impurity, and the peak intensity increased as the amount of solid solution increased. However, the peak ratio of Cu Y S to ZnS is very small, and most of CuCl is considered to form a solid solution with ZnS. (ZnS) 1-Y (CuCl) Y solid solution has good crystallinity, and when compared with the same solid solution amount, (ZnS) 0.9 (CuCl) 0.1 is Zn 0 synthesized from CuS or Cu 2 S. .9 The full width at half maximum was narrower than that of the Cu 0.1 S solid solution. This is probably because CuCl works as a flux. The diffuse reflection spectrum of the solid solution in FIG. 3 shows that (a) ZnS and (g) CuCl absorb only ultraviolet light of 400 nm or less, but absorbed up to the visible light region by dissolving ZnS and CuCl in solid solution. . (ZnS) 0.9 (CuCl) 0.1 , (ZnS) 0.85 CuCl) 0.15 , and (ZnS) 0.8 (CuCl) 0.2 have spectra having distinct absorption edges in the visible light region. It became. The spectrum (h) (i) of the Zn 0.9 Cu 0.1 S solid solution becomes a broad spectrum with a tail extending from the basic absorption of ZnS to the visible light region, and (ZnS) 0.9 ( CuCl) 0.1 .
図４は石英アンプル中において７７３Ｋで５時間熱処理することにより得られた（ＺｎＳ）０．９（ＣｕＣｌ）０．１固溶体の走査型電子顕微鏡（ＳＥＭ）による観察写真である。粒子サイズが１００−３００ｎｍ程度の結晶性のよい微粒子が観察された。ＳＥＭ−ＥＤＳの測定からは，固溶体粒子中にＣｕとＣｌとが１：１に近い比で存在していることが確認された。この固溶体のＢＥＴ比表面積は４．１ｍ２ｇ−１であった。 FIG. 4 is a scanning electron microscope (SEM) observation photograph of (ZnS) 0.9 (CuCl) 0.1 solid solution obtained by heat treatment at 773 K for 5 hours in a quartz ampule. Fine crystalline particles having a particle size of about 100-300 nm were observed. From the SEM-EDS measurement, it was confirmed that Cu and Cl were present in the solid solution particles at a ratio close to 1: 1. The BET specific surface area of this solid solution was 4.1 m 2 g −1 .
図５に、室温で測定した（ＺｎＳ）１−Ｙ（ＣｕＸ）Ｙ固溶体の励起・発光スペクトルを示す。３６５ｎｍの光で励起すると５５８ｎｍ付近に極大値をもつ鮮やかな黄色い発光を示した。これらの黄色い発光は良く知られた蛍光体である、付活剤としてＣｕ、共付活剤としてＣｌを共ドーピングしたＺｎＳのＤ−Ａ間の青または緑色の発光とは異なっていた。
図５の（ＺｎＳ）１−Ｙ（ＣｕＣｌ）Ｙ固溶体の励起スペクトル側は、Ｙ＝０．０１（ａ）、Ｙ＝０．０５（ｂ）、Ｙ＝０．１０（ｃ）、Ｙ＝０．１５（ｄ）、およびＹ＝０．２０（ｅ）であり、発光側は、Ｙ＝０．０１（ａ’）、Ｙ＝０．０５（ｂ’）、Ｙ＝０．１０（ｃ’）、Ｙ＝０．１５（ｄ’）、およびＹ＝０．２０（ｅ’）である。
FIG. 5 shows the excitation / emission spectrum of the (ZnS) 1-Y (CuX) Y solid solution measured at room temperature. When excited with 365 nm light, it showed bright yellow emission with a maximum near 558 nm. These yellow luminescences were different from the blue or green luminescence between well-known phosphors, ZnS DA, co-doped with Cu as activator and Cl as coactivator.
The excitation spectrum side of the (ZnS) 1 -Y (CuCl) Y solid solution in FIG. 5 is Y = 0.01 (a), Y = 0.05 (b), Y = 0.10 (c), Y = 0. .15 (d) and Y = 0.20 (e), and the light emission side is Y = 0.01 (a ′), Y = 0.05 (b ′), Y = 0.10 (c ′ ), Y = 0.15 (d ′), and Y = 0.20 (e ′).
光触媒反応；
図１に示す閉鎖循環系の実験装置を用いた。
パイレックス製の上方照射型反応容器Ｒ．Ｖに表１に示す触媒を０．３ｇ挿入し、反応溶液として、還元剤として０．５ｍｏｌ／ＬのＫ２ＳＯ３及び０．１ｍｏｌ／ＬのＮａ２Ｓ加えた水１５０ｍＬを加え、撹拌・循環させ、前記３００Ｗ Ｘｅランプ（λ≧４２０ｎｍ）を照射してＨ２生成速度を循環系に配設された前記のガスクロマトグラフで定量した。
結果を表１に示す。
触媒の比表面積ＢＥＴ（ｍ２／ｇ）、及びバンドギャップエネルギー（ＢＧ）も記載した。
Photocatalytic reaction;
The experimental apparatus of the closed circulatory system shown in FIG. 1 was used.
Pyrex upward irradiation reaction vessel 0.3 g of the catalyst shown in Table 1 was inserted into V, and 150 mL of water containing 0.5 mol / L K 2 SO 3 and 0.1 mol / L Na 2 S as a reducing agent was added as a reaction solution. Circulating, irradiating with the 300 W Xe lamp (λ ≧ 420 nm), the H 2 production rate was quantified by the gas chromatograph provided in the circulation system.
The results are shown in Table 1.
The specific surface area BET (m 2 / g) and band gap energy (BG) of the catalyst were also described.
表１から、ＺｎＳ単独ではほとんど活性を示さないが、ＣｕＣｌと固溶することで高い水素生成活性を示すことが分かる。光触媒活性はＹが０から０．１の間ではＣｕＣｌの割合の増加に伴い向上した。固溶量の大きなＹ＝０．１５，０．２では活性が若干低下した。これはＸＲＤからも明らかなように、固溶量の増加に伴い硫化銅の遊離の程度が大きくなることが原因であると考えられる。Ｙ＝０．１の時に最も高い水素生成活性を示した。ＣｕＳおよびＣｕ２Ｓから固相法により合成したＺｎ０．９Ｃｕ０．１Ｓ固溶体の活性は，同じ量のＣｕを固溶した（ＺｎＳ）０．９（ＣｕＣｌ）０．１と比べると低活性であった。以上の結果から、ＺｎＳとＣｕＣｌとを固溶した触媒のみが，可視光照射下において水素生成反応に高活性を示すことが明らかとなった。特にＹ＝０．０５−０．２の範囲で比較的活性の高い固溶体が得られることがわかった。
（ＺｎＳ）０．９（ＣｕＢｒ）０．１固溶体（ＢＧ；２．７７ｅＶ）も可視光領域に吸収を示し、６７３μｍｏｌ／ｈと高い水素生成活性を示した。
（ＺｎＳ）０．９（ＣｕＣｌ）０．１光触媒による水素生成反応の量子収率（ＱＹ）は、４６０ｎｍ単色光照射下においても量子収率（ＱＹ）３．１％と比較的高い値を示した。バンドギャップ遷移である４２０ｎｍの単色光照射下では、量子収率１６．３％と高い値を示した。この値は以前に報告したＣｕドーピングＺｎＳ光触媒（ＱＹ＝３．７％）よりも高く（前記非特許文献７）、発明者らの知る限り助触媒未担持という条件においては，可視光照射下での水素生成反応で最も高い値と見なせる。
From Table 1, it can be seen that ZnS alone shows little activity, but shows high hydrogen generation activity when dissolved in CuCl. The photocatalytic activity improved with increasing the proportion of CuCl when Y was between 0 and 0.1. The activity was slightly reduced at Y = 0.15 and 0.2 where the solid solution amount was large. As is clear from XRD, this is considered to be caused by an increase in the degree of liberation of copper sulfide as the amount of solid solution increases. The highest hydrogen production activity was exhibited when Y = 0.1. The activity of Zn 0.9 Cu 0.1 S solid solution synthesized from CuS and Cu 2 S by solid phase method is lower than that of (ZnS) 0.9 (CuCl) 0.1 in which the same amount of Cu is dissolved. It was active. From the above results, it has been clarified that only the catalyst in which ZnS and CuCl are dissolved is highly active in the hydrogen generation reaction under irradiation with visible light. In particular, it was found that a solid solution having a relatively high activity was obtained in the range of Y = 0.05-0.2.
(ZnS) 0.9 (CuBr) 0.1 solid solution (BG; 2.77 eV) also showed absorption in the visible light region and a high hydrogen generation activity of 673 μmol / h.
(ZnS) 0.9 (CuCl) 0.1 The quantum yield (QY) of the hydrogen production reaction with a photocatalyst shows a relatively high value of 3.1% quantum yield (QY) even under irradiation with monochromatic light at 460 nm. It was. Under a monochromatic light irradiation of 420 nm which is a band gap transition, the quantum yield was as high as 16.3%. This value is higher than the previously reported Cu-doped ZnS photocatalyst (QY = 3.7%) (Non-patent Document 7), and as far as the inventors know, under the condition that no promoter is supported under visible light irradiation. It can be regarded as the highest value in the hydrogen production reaction.
（ＺｎＳ）０．９（ＣｕＣｌ）０．１固溶体を製造する際の熱処理条件と、得られる固溶体の比表面積及び水素生成活性との相関；
表２に様々な条件で熱処理をして合成した（ＺｎＳ）０．９（ＣｕＣｌ）０．１固溶体の比表面積と水素生成反応活性の結果を示す。
(ZnS) 0.9 (CuCl) 0.1 Correlation between heat treatment conditions when producing a solid solution and the specific surface area and hydrogen generation activity of the resulting solid solution;
Table 2 shows the results of specific surface area and hydrogen generation reaction activity of (ZnS) 0.9 (CuCl) 0.1 solid solution synthesized by heat treatment under various conditions.
６７３Ｋの熱処理では，比表面積は大きいものの結晶性が悪く，触媒の色もくすんでおり低活性であった。７７３Ｋで熱処理した場合にもっとも高い活性を示し，活性は焼成時間にはあまり依存性がなかった。一方，比較的高温の８７３Ｋでの熱処理では活性が低下してしまった。 In the heat treatment at 673 K, although the specific surface area was large, the crystallinity was poor, the color of the catalyst was dull, and the activity was low. When the heat treatment was performed at 773 K, the highest activity was shown, and the activity was not very dependent on the firing time. On the other hand, the activity decreased in the heat treatment at 873 K at a relatively high temperature.
水溶液の組成と光触媒の水素生成反応との相関の測定；
還元剤としてＳ２−またはＳＯ３ ２−を含む水溶液、Ｓ２−とＳＯ３ ２−をともに含む水溶液（触媒０．３ｇ）からの水素生成反応と、良く知られたＣｄＳ（ｄ、溶液組成は０．１Ｍ Ｎａ２Ｓ＋０．５Ｍ Ｋ２ＳＯ３）との比較を図６に示す。（ａ）０．５Ｍ Ｋ２ＳＯ３下ではほとんど活性を示さなかった。（ｂ）０．１Ｍ Ｎａ２Ｓの反応では、反応初期で４００μｍｏｌ／ｈほどの高い水素生成活性を示したが２時間目以降から失活してしまった。一方、（ｃ）の０．１Ｍ Ｎａ２Ｓ＋０．５Ｍ Ｋ２ＳＯ３の反応では，ほぼ定常的に水素を生成し続けた（４６０μｍｏｌ／ｈ）。よく知られている高活性な光触媒であるＣｄＳと比較した場合、（ｃ）（ＺｎＳ）０．９（ＣｕＣｌ）０．１の方が４倍以上もの高い水素生成活性を示した。また，以前我々が報告したＣｕ（４．５ｍｏｌ％）ドーピングＺｎＳを（ｃ）と同じ反応条件下で測定すると、活性は９８μｍｏｌ／ｈであり，今回報告見出したＺｎＳ−ＣｕＣｌ固溶体の方が高い活性を示した。
Measurement of the correlation between the composition of the aqueous solution and the hydrogen production reaction of the photocatalyst;
Hydrogen generation reaction from an aqueous solution containing S 2− or SO 3 2− as a reducing agent, an aqueous solution containing both S 2− and SO 3 2− (catalyst 0.3 g), and well-known CdS (d, solution composition) FIG. 6 shows a comparison with 0.1 M Na 2 S + 0.5 M K 2 SO 3 ). (A) Almost no activity was observed under 0.5M K 2 SO 3 . (B) In the reaction of 0.1 M Na 2 S, hydrogen production activity as high as 400 μmol / h was shown at the beginning of the reaction, but it was deactivated after the second hour. On the other hand, in the reaction of 0.1 M Na 2 S + 0.5 M K 2 SO 3 in (c), hydrogen was generated almost constantly (460 μmol / h). When compared with CdS, which is a well-known highly active photocatalyst, (c) (ZnS) 0.9 (CuCl) 0.1 showed a hydrogen production activity four times higher. Moreover, when Cu (4.5 mol%) doped ZnS previously reported by us was measured under the same reaction conditions as in (c), the activity was 98 μmol / h, and the ZnS—CuCl solid solution found this time has higher activity. showed that.
疑似太陽光照射下の水素生成反応活性の測定；
（ＺｎＳ）０．９（ＣｕＣｌ）０．１固溶体触媒は、図７に示すように、疑似太陽光照射下においても高い活性を示し、比較的安定に水素を生成し続けた。因みに、反応溶液には０．３ｇの光触媒を加え、前記溶液の組成は０．１ｍｏｌ／Ｌ Ｋ２ＳＯ３＋０．５ｍｏｌ／Ｌ Ｎａ２Ｓであり、溶液の量は１５０ｍＬ、光源は３００Ｗ Ｘｅランプ（ＡＭ１．５フィルター）、照射面積３３ｃｍ２である。照射面積から換算した１平方メートル当たりの水素生成量は、反応初期で３．１Ｌｈ−１ｍ２であった。反応後の触媒はＸＲＤ観察から触媒の状態の変化は見られなかった。
Measurement of hydrogen production reaction activity under simulated sunlight irradiation;
As shown in FIG. 7, the (ZnS) 0.9 (CuCl) 0.1 solid solution catalyst showed high activity even under simulated sunlight irradiation, and continued to generate hydrogen relatively stably. Incidentally, 0.3 g of photocatalyst was added to the reaction solution, the composition of the solution was 0.1 mol / L K 2 SO 3 +0.5 mol / L Na 2 S, the amount of the solution was 150 mL, and the light source was a 300 W Xe lamp (AM1.5 filter), irradiation area 33 cm 2 . The amount of hydrogen generated per square meter converted from the irradiation area was 3.1 Lh −1 m 2 at the beginning of the reaction. As for the catalyst after the reaction, no change in the state of the catalyst was observed from XRD observation.
ＺｎＳとＣｕＣｌから調製された（ＺｎＳ）１−Ｙ（ＣｕＣｌ）Ｙ固溶体が高活性な可視光応答性光触媒であることが明らかとなり、すなわち、これらの固溶体はＰｔやＲｕといった貴金属助触媒を担持しなくても水素生成反応において高い活性を示した。疑似太陽光照射下においても水素生成反応に活性を示し、また、ＣｄＳや以前報告したＣｕドーピングＺｎＳ光触媒と比較してもより高い活性を示すことは、より産業上の利用性を可能としたものである。更に、ＣｕＣｌがフラックスとして働くことやＣｕ＋とＣｌ−の共置換による電荷補償効果がＣｕ＋の安定な価電子帯の形成に寄与していることが高活性の要因として考えられ、また、ＺｎＳとＣｕＢｒとの固溶体においてもＺｎＳ−ＣｕＣｌ固溶体と同様に可視光照射下で、水素生成反応に高い活性を示すことの発見は、水素生成反応に高い活性を示す光触媒の開発の方向性を示したことにおいても、産業上の効果は顕著である。 (ZnS) 1-Y (CuCl) Y solid solution prepared from ZnS and CuCl was found to be a highly active visible light responsive photocatalyst, that is, these solid solutions carry noble metal promoters such as Pt and Ru. Even without it, it showed high activity in the hydrogen production reaction. It shows activity in hydrogen generation reaction even under simulated sunlight irradiation, and higher activity compared to CdS and the previously reported Cu-doped ZnS photocatalyst enables more industrial applicability. It is. Further, it is considered that CuCl works as a flux, and that the charge compensation effect by co-substitution of Cu + and Cl − contributes to the formation of a stable valence band of Cu +. As in the case of the ZnS-CuCl solid solution, the discovery of high activity in the hydrogen generation reaction also showed the direction of the development of a photocatalyst exhibiting high activity in the hydrogen generation reaction. Even in this case, the industrial effect is remarkable.
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 (4)
The photocatalyst comprising a solid solution according to claim 1, wherein CuX is CuCl and / or CuBr and the reducing agent is a sulfur compound.
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