JP6230039B2 - Hydrogen generator and hydrogen generation method - Google Patents
Hydrogen generator and hydrogen generation method Download PDFInfo
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- JP6230039B2 JP6230039B2 JP2013042860A JP2013042860A JP6230039B2 JP 6230039 B2 JP6230039 B2 JP 6230039B2 JP 2013042860 A JP2013042860 A JP 2013042860A JP 2013042860 A JP2013042860 A JP 2013042860A JP 6230039 B2 JP6230039 B2 JP 6230039B2
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- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims description 108
- 239000001257 hydrogen Substances 0.000 title claims description 108
- 229910052739 hydrogen Inorganic materials 0.000 title claims description 108
- 238000000034 method Methods 0.000 title claims description 8
- 239000000758 substrate Substances 0.000 claims description 70
- 229910052751 metal Inorganic materials 0.000 claims description 45
- 239000002184 metal Substances 0.000 claims description 45
- 239000007864 aqueous solution Substances 0.000 claims description 39
- 239000003054 catalyst Substances 0.000 claims description 27
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 22
- 239000000463 material Substances 0.000 claims description 14
- 238000005192 partition Methods 0.000 claims description 12
- 239000010931 gold Substances 0.000 claims description 11
- 229910052697 platinum Inorganic materials 0.000 claims description 10
- VEALVRVVWBQVSL-UHFFFAOYSA-N strontium titanate Chemical group [Sr+2].[O-][Ti]([O-])=O VEALVRVVWBQVSL-UHFFFAOYSA-N 0.000 claims description 10
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 9
- 229910052737 gold Inorganic materials 0.000 claims description 9
- 230000001699 photocatalysis Effects 0.000 claims description 9
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 8
- 238000010521 absorption reaction Methods 0.000 claims description 7
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 7
- 238000000638 solvent extraction Methods 0.000 claims 1
- 239000011941 photocatalyst Substances 0.000 description 56
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 33
- 238000006479 redox reaction Methods 0.000 description 19
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 18
- 239000001301 oxygen Substances 0.000 description 18
- 229910052760 oxygen Inorganic materials 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 11
- 238000004519 manufacturing process Methods 0.000 description 8
- 238000006722 reduction reaction Methods 0.000 description 8
- 238000004544 sputter deposition Methods 0.000 description 8
- 238000005259 measurement Methods 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 239000000243 solution Substances 0.000 description 5
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 4
- 238000000137 annealing Methods 0.000 description 4
- 230000031700 light absorption Effects 0.000 description 4
- 239000007769 metal material Substances 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 230000001678 irradiating effect Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 229910052724 xenon Inorganic materials 0.000 description 2
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 230000032900 absorption of visible light Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000004577 artificial photosynthesis Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000002848 electrochemical method Methods 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000000635 electron micrograph Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- IXCSERBJSXMMFS-UHFFFAOYSA-N hcl hcl Chemical compound Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000029553 photosynthesis Effects 0.000 description 1
- 238000010672 photosynthesis Methods 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
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- Catalysts (AREA)
Description
本発明は、水素発生装置及び水素発生方法に関する。 The present invention relates to a hydrogen generator and a hydrogen generation method.
近年、地球規模で環境問題およびエネルギー問題が顕在化されつつあり、光触媒および太陽電池などの光エネルギー変換系の構築に関する研究が注目されている。その中でも、水素や過酸化水素などの貯蔵可能な化学エネルギーが現在注目されている。このような光エネルギーを化学エネルギーに変換する人工光合成系においては、半導体を用いた光触媒が数多く研究されており、効率を高めるために可視光の変換効率の高い光触媒の研究が盛んに行われてきている（例えば、下記特許文献１，２参照）。 In recent years, environmental problems and energy problems have become apparent on a global scale, and research on the construction of photoenergy conversion systems such as photocatalysts and solar cells has attracted attention. Among these, storable chemical energy such as hydrogen and hydrogen peroxide is currently attracting attention. In such artificial photosynthesis systems that convert light energy into chemical energy, many photocatalysts using semiconductors have been studied, and in order to increase efficiency, research has been actively conducted on photocatalysts with high visible light conversion efficiency. (For example, see Patent Documents 1 and 2 below).
また、下記特許文献３には、酸化チタンを含む半導体基板の表面の中央部に金属微細構造体が配列され、その半導体基板の裏面の全面に導電層が形成され、半導体基板を収容する容器内の金属微細構造体の配置領域が電解質溶液によって満たされた構造の光電変換装置が開示されている。このような光電変換装置によれば、可視光及び近赤外光照射に基づいてプラズモン共鳴波長において光電流が観測される。 In Patent Document 3 below, a metal microstructure is arranged at the center of the front surface of a semiconductor substrate containing titanium oxide, and a conductive layer is formed on the entire back surface of the semiconductor substrate. A photoelectric conversion device having a structure in which an arrangement region of the metal microstructure is filled with an electrolyte solution is disclosed. According to such a photoelectric conversion device, a photocurrent is observed at a plasmon resonance wavelength based on irradiation with visible light and near infrared light.
しかしながら、上記特許文献１，２記載の従来の光触媒を用いて水の酸化還元反応を発生させる場合には、過電圧が発生し可視光の効率の良いエネルギー変換が困難な傾向にあった。一方、上記特許文献３記載の光電変換装置によれば、可視光及び近赤外光照射に応じて水の酸化還元反応を誘起させて酸素や過酸化水素を発生させることが可能ではあるが、その場合には光電変換装置に電気化学測定装置を接続して外部から電圧を印加する必要がある。 However, when the redox reaction of water is generated using the conventional photocatalysts described in Patent Documents 1 and 2, an overvoltage is generated and energy conversion with high efficiency of visible light tends to be difficult. On the other hand, according to the photoelectric conversion device described in Patent Document 3, it is possible to generate oxygen or hydrogen peroxide by inducing a redox reaction of water according to irradiation with visible light and near infrared light, In that case, it is necessary to connect an electrochemical measurement device to the photoelectric conversion device and apply a voltage from the outside.
そこで、本発明は、かかる課題に鑑みて為されたものであり、外部装置を必要とせずに水の酸化還元反応を効率的に誘起させることが可能な水素発生装置を提供することを目的とする。 Therefore, the present invention has been made in view of such problems, and an object thereof is to provide a hydrogen generator capable of efficiently inducing a redox reaction of water without the need for an external device. To do.
上記課題を解決するため、本発明の水素発生装置は、光触媒材料を含む基板と、基板の一方の面に沿って複数領域に分離して配置された金属体と、基板の一方の面と反対側の他方の面に配置された水素発生触媒と、を備える。 In order to solve the above-described problems, a hydrogen generator of the present invention includes a substrate containing a photocatalytic material, a metal body arranged in a plurality of regions along one surface of the substrate, and opposite to one surface of the substrate. And a hydrogen generation catalyst disposed on the other surface of the side.
このような水素発生装置によれば、基板の両面に水を接触させた状態で金属体が配置された基板上の一方の面に光を照射することにより、基板の一方の面において水を酸化させて酸素を発生させるとともに、基板の他方の面において水を還元させて水素を発生させることができる。この場合、金属体の微細構造によって決まるプラズモン共鳴の波長域において水の光電気分解が効率よく行われると同時に、水素発生触媒によっても水の還元反応が効率的に行われる。これにより、外部装置による電圧の印加を必要とせずに水の酸化還元反応を効率的に発生させることができる。 According to such a hydrogen generator, water is oxidized on one surface of the substrate by irradiating light on one surface of the substrate on which the metal body is disposed in a state where water is in contact with both surfaces of the substrate. Thus, oxygen can be generated and water can be reduced on the other surface of the substrate to generate hydrogen. In this case, photoelectrolysis of water is efficiently performed in the plasmon resonance wavelength range determined by the microstructure of the metal body, and at the same time, the reduction reaction of water is also efficiently performed by the hydrogen generation catalyst. Thereby, the oxidation-reduction reaction of water can be efficiently generated without requiring application of a voltage by an external device.
基板を金属体と水素発生触媒とともに収容し、基板の両面に接触させた状態で水溶液を保持可能な容器をさらに備える、ことが好ましい。このような容器を備えれば、水溶液を基板の両面に容易に接触させることができ、水の酸化還元反応をより効率的に発生させることができる。 It is preferable to further include a container capable of holding the aqueous solution in a state where the substrate is accommodated together with the metal body and the hydrogen generation catalyst and is in contact with both surfaces of the substrate. If such a container is provided, the aqueous solution can be easily brought into contact with both surfaces of the substrate, and the water oxidation-reduction reaction can be generated more efficiently.
また、光触媒材料は、チタン酸ストロンチウム、或いは酸化チタンであってもよい。この場合、プラズモン共鳴吸収によって励起させた電子を電子伝導帯に効率的に遷移させることができ、水の酸化還元反応をより活性化させることができる。 The photocatalytic material may be strontium titanate or titanium oxide. In this case, electrons excited by plasmon resonance absorption can be efficiently transferred to the electron conduction band, and the redox reaction of water can be further activated.
また、金属体は、金を含むものでもよい。この場合、基板の金属体が配置された面において光に対するプラズモン共鳴吸収性を高めることができる。その結果、水の酸化還元反応をより効率的に発生させることができる。 Further, the metal body may include gold. In this case, plasmon resonance absorption with respect to light can be enhanced on the surface of the substrate on which the metal body is disposed. As a result, the redox reaction of water can be generated more efficiently.
さらに、水素発生触媒は、白金を含むものでもよい。このような水素発生触媒を備えれば、基板の水素発生触媒が配置された面において水の還元反応を活発化することができ、外部装置による電圧の印加を必要とせずに水の酸化還元反応を効率的に発生させることができる。 Further, the hydrogen generation catalyst may contain platinum. If such a hydrogen generation catalyst is provided, the reduction reaction of water can be activated on the surface of the substrate where the hydrogen generation catalyst is arranged, and the oxidation-reduction reaction of water without the need to apply a voltage by an external device. Can be generated efficiently.
本発明の水素発生方法は、光触媒材料を含む基板と、基板の一方の面に沿って複数領域に分離して配置された金属体と、基板の一の面と反対側の他方の面に配置された水素発生触媒とを備える水素発生装置を用意し、基板の両面に水溶液を接触させて保持し、基板の一方の面に向けて光を照射することを特徴としている。 The hydrogen generation method of the present invention includes a substrate containing a photocatalytic material, a metal body that is separated into a plurality of regions along one surface of the substrate, and the other surface opposite to one surface of the substrate. A hydrogen generation apparatus including the hydrogen generation catalyst prepared is prepared, the aqueous solution is held in contact with both surfaces of the substrate, and light is irradiated toward one surface of the substrate.
このような水素発生方法によれば、基板の両面に水を接触させた状態で金属体が配置された基板上の一方の面に光を照射することにより、基板の一方の面において水を酸化させて酸素を発生させるとともに、基板の他方の面において水を還元させて水素を発生させることができる。この場合、金属体の微細構造によって決まるプラズモン共鳴の波長域において水の光電気分解が効率よく行われると同時に、水素発生触媒によっても水の還元反応が効率的に行われる。これにより、外部装置による電圧の印加を必要とせずに水の酸化還元反応を効率的に発生させることができる。 According to such a hydrogen generation method, water is oxidized on one surface of the substrate by irradiating light on one surface on the substrate on which the metal body is disposed in a state where water is in contact with both surfaces of the substrate. Thus, oxygen can be generated and water can be reduced on the other surface of the substrate to generate hydrogen. In this case, photoelectrolysis of water is efficiently performed in the plasmon resonance wavelength range determined by the microstructure of the metal body, and at the same time, the reduction reaction of water is also efficiently performed by the hydrogen generation catalyst. Thereby, the oxidation-reduction reaction of water can be efficiently generated without requiring application of a voltage by an external device.
本発明によれば、外部装置を必要とせずに水の酸化還元反応を効率的に誘起させることができる。 According to the present invention, the redox reaction of water can be efficiently induced without the need for an external device.
以下、図面を参照しつつ本発明に係る水素発生装置及び水素発生方法の好適な実施形態について詳細に説明する。なお、図面の説明においては同一又は相当部分には同一符号を付し、重複する説明を省略する。また、各図面は説明用のために作成されたものであり、説明の対象部位を特に強調するように描かれている。そのため、図面における各部材の寸法比率は、必ずしも実際のものとは一致しない。 Hereinafter, preferred embodiments of a hydrogen generation apparatus and a hydrogen generation method according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Each drawing is made for the purpose of explanation, and is drawn so as to particularly emphasize the target portion of the explanation. Therefore, the dimensional ratio of each member in the drawings does not necessarily match the actual one.
図１は、本発明の好適な一実施形態に係る水素発生装置１の側面図である。この水素発生装置１は、様々な波長の入射光を捕集して、その光を局在化させて増幅させることが可能な光アンテナとしての機能を有する金属微細構造と光触媒とを組み合わせて利用することにより、広範囲の波長領域の光エネルギーを水の酸化還元反応によって化学エネルギーに変換する光電気化学セルである。 FIG. 1 is a side view of a hydrogen generator 1 according to a preferred embodiment of the present invention. The hydrogen generator 1 uses a combination of a metal microstructure and a photocatalyst that function as an optical antenna capable of collecting incident light of various wavelengths and localizing and amplifying the light. By doing so, it is a photoelectrochemical cell that converts light energy in a wide wavelength range into chemical energy by a redox reaction of water.
同図に示すように、水素発生装置１は、略円柱状の密閉容器３と、密閉容器３の内部に収容された光触媒５とにより構成されている。密閉容器３は、その内部中央に隔壁３ｃを有し、隔壁３ｃを隔てた一方の底面３ａ側に水溶液７ａを保持し、隔壁３ｃを隔てた他方の底面３ｂ側に水溶液７ｂを保持する。そして、光触媒５は、その両面５ａ，５ｂを密閉容器３の円形状の底面３ａ，３ｂにそれぞれ対向させるように、密閉容器３内の隔壁３ｃの中央部に固定されている。これにより、光触媒５は、その一方の面５ａを水溶液７ａに浸され（接触され）、また、その他方の面５ｂを水溶液７ｂに浸された（接触された）状態で密閉容器３内に保持されることになる。密閉容器３は、その底面３ａの中央に窓部３ｄが設けられ、外部から照射された可視光領域或いは近赤外光領域の波長を含む入射光Ｌを、窓部３ｄを透過させることにより光触媒５の一方の面５ａに向けて入射させることが可能に構成されている。さらに、密閉容器３の側面の底面３ａ側には排気口３ｅが設けられ、水溶液７ａ内での酸化反応によって発生した酸素を外部に取り出し可能にされ、密閉容器３の側面の底面３ｂ側には排気口３ｆが設けられ、水溶液７ｂ内での還元反応によって発生した水素を外部に取り出し可能にされている。 As shown in FIG. 1, the hydrogen generator 1 includes a substantially cylindrical sealed container 3 and a photocatalyst 5 accommodated in the sealed container 3. The hermetic container 3 has a partition wall 3c in the center of the inside thereof, holds the aqueous solution 7a on the side of one bottom surface 3a across the partition wall 3c, and holds the aqueous solution 7b on the side of the other bottom surface 3b across the partition wall 3c. And the photocatalyst 5 is being fixed to the center part of the partition 3c in the airtight container 3 so that the both surfaces 5a and 5b may face the circular bottom surfaces 3a and 3b of the airtight container 3, respectively. Thus, the photocatalyst 5 is held in the sealed container 3 with one surface 5a immersed in (contacted with) the aqueous solution 7a and the other surface 5b immersed in (contacted) the aqueous solution 7b. Will be. The sealed container 3 is provided with a window portion 3d in the center of the bottom surface 3a, and allows the incident light L including the wavelength of the visible light region or near infrared light region irradiated from the outside to pass through the window portion 3d to be a photocatalyst. 5 is configured to be incident toward one surface 5a. Further, an exhaust port 3e is provided on the side of the bottom surface 3a of the sealed container 3, so that oxygen generated by the oxidation reaction in the aqueous solution 7a can be taken out to the outside, and on the bottom surface 3b side of the side of the sealed container 3 An exhaust port 3f is provided so that hydrogen generated by the reduction reaction in the aqueous solution 7b can be taken out.
図２は、光触媒５の詳細構造を示す断面図、図３は、図１の光触媒５の表面の走査型電子顕微鏡（ＳＥＭ）像を示す図、図４は、図３に示す金属体のサイズの分布を示すグラフである。 2 is a cross-sectional view showing a detailed structure of the photocatalyst 5, FIG. 3 is a view showing a scanning electron microscope (SEM) image of the surface of the photocatalyst 5 in FIG. 1, and FIG. 4 is a size of the metal body shown in FIG. It is a graph which shows distribution of.
光触媒５は、図２に示すように、チタン酸ストロンチウム（ＳｒＴｉＯ３）或いは酸化チタン（ＴｉＯ２）等の光触媒材料を含む基板９と、基板９の表面９ａ上に沿って複数領域に分離して配列された複数の金属体１１と、基板９の表面９ａの反対側の裏面９ｂ上に沿って分離して配置された水素発生触媒１３を含んでいる。この基板９の表面９ａが光触媒５の面５ａに対応し、基板９の裏面９ｂが光触媒５の面５ｂに対応する。 As shown in FIG. 2, the photocatalyst 5 is separated into a plurality of regions along the surface 9a of the substrate 9 including a photocatalytic material such as strontium titanate (SrTiO 3 ) or titanium oxide (TiO 2 ). A plurality of metal bodies 11 arranged and a hydrogen generation catalyst 13 arranged separately along a back surface 9b opposite to the front surface 9a of the substrate 9 are included. The front surface 9 a of the substrate 9 corresponds to the surface 5 a of the photocatalyst 5, and the back surface 9 b of the substrate 9 corresponds to the surface 5 b of the photocatalyst 5.
基板９は、例えば、０．０１ｗｔ％でニオブがドープされたチタン酸ストロンチウム基板、或いはアナターゼ型酸化チタン基板であり、可視光の照射に対して水素及び酸素生成に関して活性な光触媒材料によって構成される。この基板９のサイズは例えば10mm×10mmである。そして、その基板９の表面９ａ上には複数の金属体１１が複数領域に分離して点在するように配置されている（図３）。図４に示すように、金属体１１は、その径が10nm〜100nmの範囲であり、平均径が例えば52nmの略円形状の金属膜である。 The substrate 9 is, for example, a strontium titanate substrate doped with niobium at 0.01 wt%, or an anatase-type titanium oxide substrate, and is composed of a photocatalytic material that is active with respect to hydrogen and oxygen generation when irradiated with visible light. . The size of the substrate 9 is, for example, 10 mm × 10 mm. And on the surface 9a of the board | substrate 9, the some metal body 11 is arrange | positioned so that it may be divided | segmented into a several area | region and scattered (FIG. 3). As shown in FIG. 4, the metal body 11 is a substantially circular metal film having a diameter in the range of 10 nm to 100 nm and an average diameter of, for example, 52 nm.
このような基板９上の金属体１１は、次にようにして形成される。すなわち、基板９の表面９ａにスパッタリングにより金属体１１を３ｎｍの厚さで成膜し、その後、基板９の表面９ａを窒素雰囲気下の８００°Ｃの温度で所定時間（例えば、１時間）アニール処理を施して、複数領域に分離された金属体１１を形成する。このような処理により、基板９の表面９ａ上で金属原子は温度上昇に伴って拡散し、表面拡散長の範囲内で粒径サイズが膜厚に対応してある程度制御された略円形状のアイランドが形成される。 Such a metal body 11 on the substrate 9 is formed as follows. That is, the metal body 11 is formed to a thickness of 3 nm by sputtering on the surface 9a of the substrate 9, and then the surface 9a of the substrate 9 is annealed at a temperature of 800 ° C. in a nitrogen atmosphere for a predetermined time (for example, 1 hour). Processing is performed to form a metal body 11 separated into a plurality of regions. By such treatment, metal atoms diffuse on the surface 9a of the substrate 9 as the temperature rises, and a substantially circular island in which the particle size is controlled to some extent in accordance with the film thickness within the range of the surface diffusion length. Is formed.
なお、金属体１１の材料としては金（Ａｕ）が好適に用いられる。これは、金属体１１が基板９表面を拡散しやすくアイランドが容易に形成されるためである。また、スパッタリングした金属体１１をアニール処理することは、アイランド構造を容易に作成できる点で好適である。ここで、金属体１１の材料としては、金以外にも、サイズや形状により様々な波長の入射光に対してプラズモン共鳴吸収性を有する金属材料であってもよい。このような金属材料としては、銀、銅、白金、アルミニウム及びこれらの合金等の金属材料が挙げられる。プラズモン共鳴吸収性とは、入射光と共鳴してその光を局在化して電場を増強させ、いわゆる局在表面プラズモンと言われる現象を引き起こす性質である。金属体１１の材料としてこのような金属材料を使用することで、光触媒５の表面５ａにおける可視光領域及び近赤外光領域における応答波長を、金属体１１のサイズ及び形状によって制御することができる。 Note that gold (Au) is preferably used as the material of the metal body 11. This is because the metal body 11 easily diffuses on the surface of the substrate 9 and an island is easily formed. In addition, annealing the sputtered metal body 11 is preferable because an island structure can be easily formed. Here, the material of the metal body 11 may be a metal material having plasmon resonance absorptivity for incident light with various wavelengths depending on the size and shape, in addition to gold. Examples of such a metal material include metal materials such as silver, copper, platinum, aluminum, and alloys thereof. The plasmon resonance absorptivity is a property that resonates with incident light and localizes the light to enhance the electric field, thereby causing a phenomenon called so-called localized surface plasmon. By using such a metal material as the material of the metal body 11, the response wavelength in the visible light region and near infrared light region on the surface 5 a of the photocatalyst 5 can be controlled by the size and shape of the metal body 11. .
さらに、基板９の裏面９ｂには水素発生触媒１３が分離して配置されている。この水素発生触媒１３の材料としては、水素発生の過電圧を大幅に下げる働きを有する助触媒である白金（Ｐｔ）が好適に用いられる。この水素発生触媒１３は、白金をスパッタリングすることにより例えば平均径0.8nmで複数に分離されて裏面９ｂ上に形成される。 Further, a hydrogen generation catalyst 13 is separately disposed on the back surface 9 b of the substrate 9. As a material of the hydrogen generation catalyst 13, platinum (Pt) which is a promoter having a function of greatly reducing the overvoltage of hydrogen generation is preferably used. The hydrogen generation catalyst 13 is formed on the back surface 9b by being separated into a plurality of pieces with an average diameter of 0.8 nm, for example, by sputtering platinum.
上記構成の水素発生装置１には、水溶液７ｂとして、濃度０．１Ｍ、ｐｈ１．０の塩酸（ＨＣｌ）溶液が収容され、水溶液７ａとして、濃度０．１Ｍ、ｐｈ１３．０の水酸化カリウム（ＫＯＨ）溶液が収容される。或いは、水溶液７ｂとして硫酸溶液又は硝酸溶液、水溶液７ａとして水酸化ナトリウム溶液を使用してもよい。 The hydrogen generator 1 having the above configuration contains a hydrochloric acid (HCl) solution having a concentration of 0.1 M and ph 1.0 as the aqueous solution 7b, and potassium hydroxide (KOH) having a concentration of 0.1 M and ph 13.0 as the aqueous solution 7a. ) The solution is contained. Alternatively, a sulfuric acid solution or a nitric acid solution may be used as the aqueous solution 7b, and a sodium hydroxide solution may be used as the aqueous solution 7a.
次に、上述した構成の水素発生装置１を用いた水素発生方法について詳述する。まず、水素発生装置１を用意し、密閉容器３内に水溶液７ａ，７ｂを注入することによって、光触媒５の面５ａ，５ｂそれぞれに水溶液７ａ，７ｂを接触させた状態で密閉容器３内に水溶液７ａ，７ｂを保持させる。そして、密閉容器３の窓部３ｄから光触媒５の面５ａに向けて可視光領域或いは近赤外領域の波長を含む光Ｌを入射させる。 Next, a hydrogen generation method using the hydrogen generator 1 having the above-described configuration will be described in detail. First, the hydrogen generator 1 is prepared, and the aqueous solutions 7a and 7b are injected into the sealed container 3, so that the aqueous solutions 7a and 7b are in contact with the surfaces 5a and 5b of the photocatalyst 5, respectively. 7a and 7b are held. Then, light L including a wavelength in the visible light region or near-infrared region is incident from the window portion 3d of the sealed container 3 toward the surface 5a of the photocatalyst 5.
その結果、光触媒５の面５ａ（基板９の表面９ａ）において金属体１１によるプラズモン増強により金の電子が励起され基板９の光触媒材料の電子伝導帯に移動させられ、その電子により光触媒５の面５ｂ（基板９の裏面９ｂ）において水溶液７ｂ中の水の還元反応が引き起こされる。この水の還元反応は、下記化学式；
２ｅ−＋２Ｈ＋→Ｈ２
で表されるような反応であり、このような反応により水溶液７ｂ中の光触媒５の面５ｂ近傍で水素が生成され、排気口３ｆから排出される。
As a result, gold electrons are excited on the surface 5a of the photocatalyst 5 (surface 9a of the substrate 9) by the plasmon enhancement by the metal body 11, and moved to the electron conduction band of the photocatalytic material of the substrate 9, and the surface of the photocatalyst 5 by the electrons. 5b (the back surface 9b of the substrate 9) causes a reduction reaction of water in the aqueous solution 7b. This water reduction reaction has the following chemical formula:
2e − + 2H + → H 2
By this reaction, hydrogen is generated near the surface 5b of the photocatalyst 5 in the aqueous solution 7b and discharged from the exhaust port 3f.
また、同時に、電子の移動により光触媒５の面５ａ側にホールが生成され、そのホールが基板９の光触媒材料の表面準位にトラップされる。そして、そのホールにより水溶液７ａ中の水酸化物イオンの酸化反応が引き起こされる。この水の酸化反応は、下記化学式；
４ｈ＋＋４ＯＨ−→Ｏ２＋２Ｈ２Ｏ
で表されるような反応であり、このような反応により水溶液中７ａの光触媒５の面５ａ近傍で酸素が生成され、排気口３ｅから排出される。
At the same time, holes are generated on the surface 5 a side of the photocatalyst 5 by the movement of electrons, and the holes are trapped in the surface level of the photocatalytic material of the substrate 9. And the oxidation reaction of the hydroxide ion in the aqueous solution 7a is caused by the hole. This water oxidation reaction has the following chemical formula:
4h + + 4OH − → O 2 + 2H 2 O
By this reaction, oxygen is generated near the surface 5a of the photocatalyst 5 in the aqueous solution 7a, and is discharged from the exhaust port 3e.
以上説明した水素発生装置１及びそれを用いた水素発生方法によれば、光触媒５の両面５ａ，５ｂのそれぞれに水溶液７ａ，７ｂを接触させた状態で金属体１１が配置された光触媒５の表面５ａに光を照射することにより、光触媒５の表面５ａにおいて水溶液７ａを酸化させて酸素を発生させるとともに、光触媒５の裏面５ｂにおいて水溶液７ｂを還元させて水素を発生させることができる。この場合、金属体１１の微細構造によって決まるプラズモン共鳴の波長域において水の光電気分解が効率よく行われると同時に、水素発生触媒１３によっても水の還元反応が効率的に行われる。これにより、外部装置による電圧の印加を必要とせずに、太陽光等の可視光成分或いは近赤外光成分を含む光の照射だけで、水の酸化還元反応を効率的に発生させることができる。さらに、太陽エネルギーの波長帯域にプラズモン共鳴波長が一致するように金属体１１の構造を制御すれば、太陽エネルギーを効率的に化学エネルギーに変換することができ、反応中心波長が680nm程度である植物の光合成にも劣らないシステムの構築が可能である。 According to the hydrogen generator 1 described above and the hydrogen generation method using the same, the surface of the photocatalyst 5 in which the metal body 11 is disposed in a state where the aqueous solutions 7a and 7b are in contact with both surfaces 5a and 5b of the photocatalyst 5, respectively. By irradiating light to 5a, the aqueous solution 7a is oxidized on the surface 5a of the photocatalyst 5 to generate oxygen, and the aqueous solution 7b is reduced on the back surface 5b of the photocatalyst 5 to generate hydrogen. In this case, photoelectrolysis of water is efficiently performed in the plasmon resonance wavelength range determined by the fine structure of the metal body 11, and at the same time, the reduction reaction of water is also efficiently performed by the hydrogen generation catalyst 13. Thereby, the oxidation-reduction reaction of water can be efficiently generated only by irradiation of light containing visible light components such as sunlight or near-infrared light components without requiring application of a voltage by an external device. . Furthermore, if the structure of the metal body 11 is controlled so that the plasmon resonance wavelength matches the wavelength band of solar energy, the solar energy can be efficiently converted into chemical energy, and the reaction center wavelength is about 680 nm. It is possible to construct a system that is not inferior to photosynthesis.
また、水素発生装置１は、光触媒５の両面５ａ，５ｂのそれぞれに接触させた状態で水溶液７ａ，７ｂを保持可能な密閉容器３を備えるので、水溶液７ａ，７ｂにおける酸化還元反応をより効率的に発生させることができる。 Moreover, since the hydrogen generator 1 includes the sealed container 3 that can hold the aqueous solutions 7a and 7b in contact with both surfaces 5a and 5b of the photocatalyst 5, the oxidation-reduction reaction in the aqueous solutions 7a and 7b is more efficient. Can be generated.
また、水素発生装置１では、基板９の材料としてチタン酸ストロンチウム或いは酸化チタンが用いられているので、プラズモン共鳴吸収によって励起させた電子を電子伝導帯に効率的に遷移させることができ、水溶液７ａ，７ｂにおける酸化還元反応をより活性化させることができる。また、光触媒５に形成された金属体１１は金を材料としているので、基板９の面９ａにおいて光に対するプラズモン共鳴吸収性を高めることができる。その結果、水溶液７ａ，７ｂにおける酸化還元反応をより効率的に発生させることができる。さらに、水素発生触媒１３は白金によって形成されているので、基板９の面９ｂにおいて水溶液７ｂの還元反応を活発化することができ、外部装置による電圧の印加を必要とせずに水溶液７ａ，７ｂの酸化還元反応を効率的に発生させることができる。 In the hydrogen generator 1, since strontium titanate or titanium oxide is used as the material of the substrate 9, electrons excited by plasmon resonance absorption can be efficiently transferred to the electron conduction band, and the aqueous solution 7a. , 7b can be further activated. In addition, since the metal body 11 formed on the photocatalyst 5 is made of gold, the plasmon resonance absorption with respect to light can be enhanced on the surface 9a of the substrate 9. As a result, the redox reaction in the aqueous solutions 7a and 7b can be generated more efficiently. Furthermore, since the hydrogen generation catalyst 13 is formed of platinum, the reduction reaction of the aqueous solution 7b can be activated on the surface 9b of the substrate 9, and the aqueous solutions 7a and 7b can be activated without applying voltage by an external device. An oxidation-reduction reaction can be generated efficiently.
以下、本実施形態にかかる水素発生装置１の特性測定結果を示す。 Hereinafter, the characteristic measurement result of the hydrogen generator 1 concerning this embodiment is shown.
まず、図５は、光Ｌの照射時間に対する水素生成量の関係を示すグラフである。このとき、基板９としてニオブドープチタン酸ストロンチウム基板を使用し、金からなる金属体１１を８００°Ｃで１時間アニール処理を施すことにより形成し、白金からなる水素発生触媒１３をそれぞれ３０秒、４０秒、５０秒、６０秒の間スパッタリングすることにより生成した複数種類の光触媒５を用意した。さらに、金属体１１を含まない光触媒（ｗ／ｏ Ａｕ）、及び水素発生触媒１３を含まない光触媒（ｗ／ｏ Ｐｔ）も用意した。これらの複数種類の光触媒を収容した水素発生装置１に対して、キセノンランプを用いて波長450nm〜850nmの可視光領域及び近赤外光領域を含む光Ｌを照射し、発生した水素量を比較した。この結果から、水素発生量は４０秒ほど白金をスパッタリングしたものが最も多く、以下、５０秒スパッタリングしたもの、３０秒スパッタリングしたもの、６０秒スパッタリングしたものの順に水素発生量が多かった。さらに、それぞれの光触媒５を使用したものにおいては、照射時間と水素発生量の関係はほぼ比例関係であった。一方、水素発生触媒１３を含まない光触媒に関しては、それを含む光触媒５に比較して水素発生量が低下し、金属体１１を含まない光触媒に関しては、他の光触媒に比較して極端に水素発生量が低下することが分かった。このことからも、金属体１１及び水素発生触媒１３の組み合わせが水の酸化還元反応を効果的に活性化させていることが分かった。さらに、水素発生触媒１３の構成も水の酸化還元反応に影響していることも分かった。 First, FIG. 5 is a graph showing the relationship of the amount of hydrogen generation with respect to the irradiation time of the light L. At this time, a niobium-doped strontium titanate substrate is used as the substrate 9, and the metal body 11 made of gold is formed by annealing at 800 ° C. for 1 hour, and the hydrogen generation catalyst 13 made of platinum is respectively 30 seconds. A plurality of types of photocatalysts 5 produced by sputtering for 40 seconds, 50 seconds, and 60 seconds were prepared. Furthermore, a photocatalyst (w / o Au) not containing the metal body 11 and a photocatalyst (w / o Pt) not containing the hydrogen generation catalyst 13 were also prepared. A hydrogen generator 1 containing these multiple types of photocatalysts is irradiated with light L including a visible light region and a near infrared light region having a wavelength of 450 nm to 850 nm using a xenon lamp, and the amount of generated hydrogen is compared. did. From this result, the amount of hydrogen generation was the most when platinum was sputtered for about 40 seconds. Hereinafter, the amount of hydrogen generation was large in the order of 50 seconds sputtering, 30 seconds sputtering, and 60 seconds sputtering. Further, in each of the photocatalysts 5 used, the relationship between the irradiation time and the amount of hydrogen generation was almost proportional. On the other hand, the photocatalyst not including the hydrogen generating catalyst 13 has a lower hydrogen generation amount than the photocatalyst 5 including the photocatalyst, and the photocatalyst not including the metal body 11 is significantly more hydrogen generating than the other photocatalyst. The amount was found to decrease. This also shows that the combination of the metal body 11 and the hydrogen generation catalyst 13 effectively activates the redox reaction of water. Furthermore, it has been found that the configuration of the hydrogen generating catalyst 13 also affects the redox reaction of water.
また、図６は、光Ｌの照射時間に対する水素及び酸素の生成量の関係を示すグラフである。このとき、基板９としてニオブドープチタン酸ストロンチウム基板を使用し、金からなる金属体１１を８００°Ｃで１時間アニール処理を施すことにより形成し、白金からなる水素発生触媒１３を４０秒の間膜厚0.8nmでスパッタリングすることにより生成した一種類の光触媒５を用意した。この光触媒５を収容した水素発生装置１に対して、キセノンランプを用いて波長450nm〜850nmの可視光領域及び近赤外光領域を含む光Ｌを照射し、発生した水素量及び酸素量を測定した。この結果から、水素発生量と酸素発生量の関係は、全ての照射時間において化学量論比である２：１に近いことが分かった。これにより、水素発生装置１で引き起こされる反応は化学量論的にも水の酸化還元反応であることが明らかにされた。 FIG. 6 is a graph showing the relationship between the amount of hydrogen and oxygen produced with respect to the irradiation time of the light L. At this time, a niobium-doped strontium titanate substrate is used as the substrate 9, the metal body 11 made of gold is formed by annealing at 800 ° C. for 1 hour, and the hydrogen generating catalyst 13 made of platinum is formed for 40 seconds. One kind of photocatalyst 5 produced by sputtering with a film thickness of 0.8 nm was prepared. The hydrogen generator 1 containing the photocatalyst 5 is irradiated with light L including a visible light region and a near infrared light region having a wavelength of 450 nm to 850 nm using a xenon lamp, and the amount of generated hydrogen and oxygen are measured. did. From this result, it was found that the relationship between the hydrogen generation amount and the oxygen generation amount was close to the stoichiometric ratio of 2: 1 at all irradiation times. Thereby, it was clarified that the reaction caused in the hydrogen generator 1 is a redox reaction of water stoichiometrically.
また、図７は、光触媒５の表面５ａにおける入射光Ｌの波長に対する吸光特性を示すグラフであり、図８は、入射光Ｌの波長範囲を様々変更した場合の光Ｌの照射時間に対する水素生成量の関係を示すグラフである。このとき、基板９としてニオブドープチタン酸ストロンチウム基板を使用し、金からなる金属体１１を８００°Ｃで１時間アニール処理を施すことにより形成し、白金からなる水素発生触媒１３を４０秒の間膜厚0.8nmでスパッタリングすることにより生成した一種類の光触媒５を用意した。このように、光触媒５の表面５ａの吸光特性（すなわち、プラズモン共鳴スペクトル）が波長ピーク約610ｎｍであり波長450nm〜950nmの範囲で分布している場合において、波長範囲450-850nm、550-850nm、650-850nm、及び750-850nmの入射光Ｌをそれぞれ水素発生装置１に照射し、それに応じて発生した水素生成量を測定した。この結果より、照射時間に関わらず入射光Ｌの波長範囲が広がるにしたがって、水素の発生量が増加することが分かった。また、それぞれの水素発生量の測定結果の差分から、入射光Ｌの波長範囲450-550nm（Δλ１）、波長範囲550-650nm（Δλ２）、波長範囲650-750nm（Δλ３）、及び波長範囲750nm-850nm（Δλ４）の光成分に対する水素生成量Ａ１，Ａ２，Ａ３，Ａ４を評価した（図８）。また、図７には、評価されたそれぞれの水素生成量Ａ１，Ａ２，Ａ３，Ａ４を棒グラフであわせて示した。その結果、波長範囲Δλ１、Δλ２、Δλ３、Δλ４における水素生成量Ａ１，Ａ２，Ａ３，Ａ４は、それぞれ、基本的には、光触媒５の吸光特性（プラズモン共鳴スペクトル）の該当波長範囲Δλ１、Δλ２、Δλ３、Δλ４の積分値に対応していることが判明した。このことから、光触媒５による水分解による水素の生成が、可視光の吸収によって誘起されていることが証明された。 FIG. 7 is a graph showing the light absorption characteristics with respect to the wavelength of the incident light L on the surface 5a of the photocatalyst 5, and FIG. 8 shows hydrogen generation with respect to the irradiation time of the light L when the wavelength range of the incident light L is variously changed. It is a graph which shows the relationship of quantity. At this time, a niobium-doped strontium titanate substrate is used as the substrate 9, the metal body 11 made of gold is formed by annealing at 800 ° C. for 1 hour, and the hydrogen generating catalyst 13 made of platinum is formed for 40 seconds. One kind of photocatalyst 5 produced by sputtering with a film thickness of 0.8 nm was prepared. Thus, in the case where the light absorption characteristic (that is, plasmon resonance spectrum) of the surface 5a of the photocatalyst 5 has a wavelength peak of about 610 nm and is distributed in the wavelength range of 450 nm to 950 nm, the wavelength ranges 450 to 850 nm, 550 to 850 nm, The hydrogen generator 1 was irradiated with incident light L of 650-850 nm and 750-850 nm, respectively, and the amount of generated hydrogen was measured accordingly. From this result, it was found that the amount of hydrogen generated increases as the wavelength range of the incident light L increases regardless of the irradiation time. Further, from the difference between the measurement results of the respective hydrogen generation amounts, the wavelength range 450-550 nm (Δλ1), the wavelength range 550-650 nm (Δλ2), the wavelength range 650-750 nm (Δλ3), and the wavelength range 750 nm− of the incident light L Hydrogen production amounts A1, A2, A3, and A4 with respect to an optical component of 850 nm (Δλ4) were evaluated (FIG. 8). FIG. 7 also shows the evaluated hydrogen production amounts A1, A2, A3, and A4 together with a bar graph. As a result, the hydrogen generation amounts A1, A2, A3, and A4 in the wavelength ranges Δλ1, Δλ2, Δλ3, and Δλ4 are basically the corresponding wavelength ranges Δλ1, Δλ2, and the absorption characteristics (plasmon resonance spectrum) of the photocatalyst 5, respectively. It was found that it corresponds to the integrated values of Δλ3 and Δλ4. From this, it was proved that hydrogen generation by water splitting by the photocatalyst 5 was induced by absorption of visible light.
さらに、図６及び図８の測定結果において使用した光触媒５と同一構成の光触媒５を対象にして、照射する入射光Ｌの波長帯域を変更して測定を行った。図９には、照射する入射光Ｌの強度の波長特性を示すグラフであり、実線に入射光Ｌの波長特性を、点線に光触媒５の表面５ａにおける入射光Ｌの波長に対する吸光特性（すなわち、プラズモン共鳴スペクトル）を、それぞれ示している。図９に示すように、入射光Ｌとしては、波長範囲550-650nm、中心波長600nm、照射強度0.7W/cm2の光を照射した。 Furthermore, the measurement was performed by changing the wavelength band of the incident light L to be irradiated on the photocatalyst 5 having the same configuration as that of the photocatalyst 5 used in the measurement results of FIGS. FIG. 9 is a graph showing the wavelength characteristics of the intensity of the incident light L to be irradiated. The solid line represents the wavelength characteristics of the incident light L, and the dotted line represents the light absorption characteristics with respect to the wavelength of the incident light L on the surface 5a of the photocatalyst 5. The plasmon resonance spectrum is shown respectively. As shown in FIG. 9, the incident light L was irradiated with light having a wavelength range of 550 to 650 nm, a center wavelength of 600 nm, and an irradiation intensity of 0.7 W / cm 2 .
上記の測定条件において、まず、照射時間と水素及び酸素の発生量との関係を測定した。図１０は、入射光Ｌの照射時間に対する水素及び酸素の生成量の関係を示すグラフである。この結果から、図６に示した測定結果と同様に、水素発生量と酸素発生量の関係は、全ての照射時間において化学量論比である２：１に近いことが分かった。これにより、照射光の波長を狭帯域化した場合でも、水素発生装置１で引き起こされる反応は化学量論的にも水の酸化還元反応であることが明らかにされた。 Under the above measurement conditions, first, the relationship between the irradiation time and the generation amounts of hydrogen and oxygen was measured. FIG. 10 is a graph showing the relationship between the generation time of hydrogen and oxygen with respect to the irradiation time of the incident light L. From this result, it was found that the relationship between the hydrogen generation amount and the oxygen generation amount was close to the stoichiometric ratio of 2: 1 at all irradiation times, as in the measurement results shown in FIG. Thereby, even when the wavelength of irradiation light was narrowed, it was clarified that the reaction caused by the hydrogen generator 1 is a redox reaction of water stoichiometrically.
次に、光触媒５の裏面５ｂ側の水溶液７ｂをｐｈ１．０で固定した状態で、表面５ａ側の水溶液７ａのｐｈを１３．０〜１０．０の範囲で変化させた場合の水素及び酸素の生成率（時間当たりの生成量）を測定した（図１１）。その結果、水溶液７ａのｐｈが上昇するほど（強アルカリ性であるほど）水素及び酸素の生成率は急激に上昇することが明らかにされた。 Next, in a state where the aqueous solution 7b on the back surface 5b side of the photocatalyst 5 is fixed at ph1.0, hydrogen and oxygen in the case where the ph of the aqueous solution 7a on the front surface 5a side is changed in the range of 13.0 to 10.0. The production rate (production amount per hour) was measured (FIG. 11). As a result, it has been clarified that as the pH of the aqueous solution 7a increases (the stronger the alkalinity), the generation rates of hydrogen and oxygen increase rapidly.
なお、本発明は、上述した実施形態に限定されるものではない。例えば、水素発生装置１には窓部３ｄが設けられて、窓部３ｄを介して入射光を光触媒５の表面５ａに入射させるように構成されているが、それに加えて密閉容器３の窓部４ｄの反対側に（例えば、底面３ｂに）さらに窓部を設けて、光触媒５ｂの裏面５ｂに外部から光を入射可能に構成されていてもよい。このような構造によれば、外部から紫外光を光触媒５ｂの裏面５ｂに入射することにより、酸化チタン、チタン酸ストロンチウム等を含む基板９を励起させて水素を発生させることが可能になり、表面５ａに可視光或いは近赤外光、裏面５ｂに紫外光を同時入射させればより効率的に水素を発生させることができる。 In addition, this invention is not limited to embodiment mentioned above. For example, the hydrogen generator 1 is provided with a window portion 3d so that incident light is incident on the surface 5a of the photocatalyst 5 through the window portion 3d. A window portion may be further provided on the opposite side of 4d (for example, on the bottom surface 3b) so that light can be incident on the back surface 5b of the photocatalyst 5b from the outside. According to such a structure, it becomes possible to generate hydrogen by exciting the substrate 9 containing titanium oxide, strontium titanate, etc. by making ultraviolet light incident on the back surface 5b of the photocatalyst 5b from the outside. If visible light or near-infrared light is incident on 5a and ultraviolet light is incident on the back surface 5b simultaneously, hydrogen can be generated more efficiently.
１…水素発生装置、３…密閉容器、５…光触媒、５ａ…表面、５ｂ…裏面、７ａ，７ｂ…水溶液、９…基板、９ａ…表面、９ｂ…裏面、１１…金属体、１３…水素発生触媒、Ｌ…光。 DESCRIPTION OF SYMBOLS 1 ... Hydrogen generator, 3 ... Sealed container, 5 ... Photocatalyst, 5a ... Front surface, 5b ... Back surface, 7a, 7b ... Aqueous solution, 9 ... Substrate, 9a ... Front surface, 9b ... Back surface, 11 ... Metal body, 13 ... Hydrogen generation Catalyst, L ... light.
Claims (4)
前記基板の一方の面に沿って複数領域に分離して配置され、プラズモン共鳴吸収性を有する金属体と、
前記基板の前記一方の面と反対側の他方の面に配置された水素発生触媒と、
前記基板を前記金属体と前記水素発生触媒とともに収容し、前記基板の両面に接触させた状態で水溶液を保持可能な容器と、
を備え、
前記容器は、内部を隔てる隔壁を有し、前記隔壁の中央に前記基板を保持し、
前記容器の内部において、前記隔壁を隔てた前記基板の前記一方の面側に前記一方の面に接触させるように第１の水溶液が保持され、
前記容器の内部において、前記隔壁を隔てた前記基板の前記他方の面側に前記他方の面に接触させるように第２の水溶液が保持される、
ことを特徴とする水素発生装置。 A substrate comprising a photocatalytic material that is strontium titanate or titanium oxide ;
A metal body that is arranged in a plurality of regions along one surface of the substrate and has plasmon resonance absorption ; and
A hydrogen generating catalyst disposed on the other surface opposite to the one surface of the substrate;
Containing the substrate together with the metal body and the hydrogen generating catalyst, and a container capable of holding an aqueous solution in contact with both surfaces of the substrate;
Equipped with a,
The container has a partition partitioning the inside, and holds the substrate in the center of the partition,
Inside the container, a first aqueous solution is held so as to contact the one surface on the one surface side of the substrate across the partition;
Inside the container, a second aqueous solution is held so as to contact the other surface on the other surface side of the substrate across the partition.
A hydrogen generator characterized by that.
ことを特徴とする請求項１に記載の水素発生装置。 The metal body includes gold,
The hydrogen generator according to claim 1 .
ことを特徴とする請求項１又は２に記載の水素発生装置。 The hydrogen generation catalyst includes platinum.
The hydrogen generator according to claim 1 or 2 , characterized in that.
前記容器には、内部を隔てる隔壁が設けられ、前記隔壁の中央に前記基板が保持され、
前記容器の内部において、前記隔壁を隔てた前記基板の前記一方の面側に前記一方の面に接触させるように第１の水溶液を保持し、
前記容器の内部において、前記隔壁を隔てた前記基板の前記他方の面側に前記他方の面に接触させるように第２の水溶液を保持し、
前記基板の前記一方の面に向けて光を照射する、
ことを特徴とする水素発生方法。 A substrate including a photocatalytic material is a strontium titanate or titanium oxide, they are disposed separately into a plurality of regions along the one surface of the substrate, and the metal body having a plasmon resonance absorption properties, of the hand of the substrate A hydrogen generation catalyst disposed on the other surface opposite to the surface, and a container that holds the substrate together with the metal body and the hydrogen generation catalyst and can hold an aqueous solution in contact with both surfaces of the substrate. Prepare a hydrogen generator with
The container is provided with a partition that separates the interior, and the substrate is held in the center of the partition,
Inside the container, hold the first aqueous solution so as to contact the one surface on the one surface side of the substrate across the partition,
Inside the container, hold the second aqueous solution so as to contact the other surface on the other surface side of the substrate across the partition,
It emits light toward the surface of the hand of the substrate,
A method for generating hydrogen.
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