JPH11216364A - Photocatalyst - Google Patents
PhotocatalystInfo
- Publication number
- JPH11216364A JPH11216364A JP10019319A JP1931998A JPH11216364A JP H11216364 A JPH11216364 A JP H11216364A JP 10019319 A JP10019319 A JP 10019319A JP 1931998 A JP1931998 A JP 1931998A JP H11216364 A JPH11216364 A JP H11216364A
- Authority
- JP
- Japan
- Prior art keywords
- photocatalyst
- metal element
- visible light
- hydrogen
- precursor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000011941 photocatalyst Substances 0.000 title claims abstract description 98
- 229910052751 metal Inorganic materials 0.000 claims abstract description 46
- 239000002184 metal Substances 0.000 claims abstract description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 31
- 239000002243 precursor Substances 0.000 claims abstract description 30
- 239000000126 substance Substances 0.000 claims abstract description 24
- 239000001257 hydrogen Substances 0.000 claims abstract description 23
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 23
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 21
- 238000010306 acid treatment Methods 0.000 claims abstract description 20
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000001301 oxygen Substances 0.000 claims abstract description 19
- 239000002131 composite material Substances 0.000 claims abstract description 16
- 239000010419 fine particle Substances 0.000 claims description 20
- 239000013618 particulate matter Substances 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 229910052733 gallium Inorganic materials 0.000 claims description 4
- 229910052748 manganese Inorganic materials 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 3
- 150000001875 compounds Chemical class 0.000 claims description 2
- 230000003197 catalytic effect Effects 0.000 abstract description 27
- 239000011236 particulate material Substances 0.000 abstract description 4
- 101150113811 abo2 gene Proteins 0.000 abstract 1
- 239000003054 catalyst Substances 0.000 description 9
- 239000012298 atmosphere Substances 0.000 description 6
- 239000011261 inert gas Substances 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 6
- 238000000354 decomposition reaction Methods 0.000 description 5
- 239000002803 fossil fuel Substances 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000010304 firing Methods 0.000 description 4
- 229910017604 nitric acid Inorganic materials 0.000 description 4
- 238000010298 pulverizing process Methods 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 238000010532 solid phase synthesis reaction Methods 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- 229910005191 Ga 2 O 3 Inorganic materials 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000004570 mortar (masonry) Substances 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 238000000634 powder X-ray diffraction Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical class S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 2
- 229910052815 sulfur oxide Inorganic materials 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
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical class OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003426 co-catalyst Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000011799 hole material Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 239000005297 pyrex Substances 0.000 description 1
- 238000011002 quantification Methods 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- -1 silver ions Chemical class 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
Landscapes
- Catalysts (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、可視光照射下にお
いて水を分解し、水素と酸素のうち少なくとも一方を生
成させる可視光領域で触媒活性を有する光触媒に関する
ものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst having catalytic activity in a visible light region that decomposes water under irradiation with visible light and generates at least one of hydrogen and oxygen.
【０００２】[0002]
【従来の技術】現在、エネルギー源としては主として、
石油や石炭等の化石燃料と原子力エネルギーが用いられ
ている。しかし、化石燃料は、その埋蔵量が有限であり
枯渇が問題視されている。また、化石燃料は、燃焼させ
た際に二酸化炭素、窒素酸化物、硫黄酸化物等を排出
し、その結果、二酸化炭素は地球の温暖化をもたらし、
窒素酸化物や硫黄酸化物は空気中の水分と反応して硝酸
や硫酸を生成して酸性雨となり、地球環境の破壊をもた
らしている。2. Description of the Related Art At present, energy sources mainly include:
Fossil fuels such as oil and coal and nuclear energy are used. However, fossil fuels have a finite reserve and depletion is a problem. Also, fossil fuels emit carbon dioxide, nitrogen oxides, sulfur oxides, etc. when burned, and as a result, carbon dioxide causes global warming,
Nitrogen oxides and sulfur oxides react with moisture in the air to produce nitric acid and sulfuric acid, resulting in acid rain and destruction of the global environment.
【０００３】また、新しいエネルギー源である原子力エ
ネルギーを利用すべく原子力発電が実用化されている
が、安全性や廃棄物処理等の問題を抱えている。このよ
うな状況の下で、エネルギー資源枯渇や地球環境破壊の
問題を解決する一つの方法として、クリーンなエネルギ
ー源である水素の利用が注目されている。水素は燃焼さ
せても水になるだけであり、環境汚染を引き起こさな
い。なお、この水素を発生させるために、化石燃料等を
用いたのでは意味がないことは言うまでもない。[0003] Nuclear power generation has been put into practical use to utilize nuclear energy, which is a new energy source, but has problems such as safety and waste disposal. Under such circumstances, attention has been paid to the use of hydrogen, which is a clean energy source, as one method for solving the problems of depletion of energy resources and destruction of the global environment. Hydrogen only turns into water when burned, and does not cause environmental pollution. Needless to say, it is meaningless to use fossil fuel or the like to generate this hydrogen.
【０００４】埋蔵量が有限である化石燃料に対して、太
陽光は無尽蔵にあり、水も地球には大量にある。そこ
で、太陽光のエネルギーを利用して水を分解することに
より水素を生成すれば、前記の各問題を解決することが
できる。そして、太陽光のエネルギーを利用して水を分
解する手段の一つとして水分解用の光触媒がある。光触
媒は一種の半導体であり、そのバンドギャップ以上のエ
ネルギーを吸収すると、ホール（正孔）とエレクトロン
（電子）を生成し、ホールが水を酸化して酸素を生成
し、エレクトロンが水を還元して水素を生成する機能を
有する。[0004] For fossil fuels with finite reserves, sunlight is inexhaustible and water is abundant on the earth. Then, if hydrogen is generated by decomposing water using the energy of sunlight, each of the above-mentioned problems can be solved. As one of the means for decomposing water using the energy of sunlight, there is a photocatalyst for water decomposition. A photocatalyst is a type of semiconductor. When it absorbs energy above its band gap, it generates holes (holes) and electrons (electrons), which oxidizes water to generate oxygen, and electrons reduce water. To generate hydrogen.
【０００５】ところで、地表で得られる太陽光は、波長
５００nm付近にピークを持つスペクトル分布を示す。ま
た、その分布割合は、紫外線領域（波長４００nm未満）
が約５％、可視光領域（波長４００nm以上、７５０nm未
満）が約４３％、赤外線領域（波長７５０nm以上）が約
５２％である。そのため、太陽光を効率良く利用するた
めには、バンドギャップのエネルギーが前記分布割合が
大きい可視光領域以上（波長４００nm以上）の光エネル
ギーに相当する光触媒（可視光領域で触媒活性を有する
光触媒）が望まれる。[0005] Incidentally, sunlight obtained on the ground surface has a spectrum distribution having a peak near a wavelength of 500 nm. The distribution ratio is in the ultraviolet region (wavelength less than 400 nm).
Is about 5%, the visible light region (wavelength 400 nm or more, less than 750 nm) is about 43%, and the infrared light region (wavelength 750 nm or more) is about 52%. Therefore, in order to use sunlight efficiently, a photocatalyst whose bandgap energy corresponds to light energy in the visible light region or more (wavelength 400 nm or more) where the distribution ratio is large (a photocatalyst having catalytic activity in the visible light region). Is desired.
【０００６】[0006]
【発明が解決しようとする課題】かかる可視光領域で触
媒活性を有する光触媒としては、例えば化学式ａｂＯ2
（ａ：１種または２種以上の１価の金属元素、ｂ：１種
または２種以上の３価の金属元素、（例）ＣｕＦｅ
Ｏ2）で表され、デラフォサイト（Delafossite）型の結
晶構造を有する微粒子状物質からなる光触媒がある。As such a photocatalyst having a catalytic activity in the visible light region, for example, the chemical formula abO 2
(A: one or more monovalent metal elements, b: one or more trivalent metal elements, (Example) CuFe
There is a photocatalyst composed of particulate matter represented by O 2 ) and having a delafossite crystal structure.
【０００７】この光触媒は、通常の固相法により、即ち
原料となる各金属元素成分の酸化物を所定組成の比率に
て混合し、不活性ガス雰囲気中で焼成することにより製
造できる。或いは、この光触媒は、原料となる各金属元
素成分の酸化物を所定組成の比率にて混合し、不活性ガ
ス雰囲気中で焼成することにより前駆体である粒子状物
質を合成した後、この前駆体を粉砕して微粒子状にする
ことにより製造できる。This photocatalyst can be produced by a usual solid-phase method, that is, by mixing oxides of respective metal element components as raw materials at a predetermined composition ratio and firing in an inert gas atmosphere. Alternatively, this photocatalyst is prepared by mixing oxides of respective metal element components as raw materials at a predetermined composition ratio and firing in an inert gas atmosphere to synthesize a particulate material as a precursor. It can be manufactured by pulverizing the body into fine particles.
【０００８】例えば、Ｃｕの酸化物とＦｅの酸化物を所
定組成の比率にて混合し、不活性ガス雰囲気中で焼成す
ることにより合成した光触媒の前駆体（粒子状のＣｕＦ
ｅＯX）をさらに粉砕することにより光触媒（微粒子状
のＣｕＦｅＯX）を製造できる。しかしながら、前記化
学式ａｂＯ2で表され、デラフォサイト型の結晶構造を
有するとされる微粒子状物質からなる従来の光触媒は、
可視光照射下において水を水素と酸素に分解する機能
（触媒活性）を有するものの、その触媒活性がかなり低
いという問題点があった。For example, a precursor (particulate CuF) of a photocatalyst synthesized by mixing an oxide of Cu and an oxide of Fe at a predetermined composition ratio and firing in an inert gas atmosphere.
eO x ) can be further pulverized to produce a photocatalyst (particulate CuFeO x ). However, a conventional photocatalyst represented by the chemical formula abO 2 and composed of a particulate material having a delafossite-type crystal structure,
Although it has a function of decomposing water into hydrogen and oxygen under visible light irradiation (catalytic activity), there is a problem that its catalytic activity is considerably low.
【０００９】本発明は、かかる問題点に鑑みてなされた
ものであり、可視光領域において従来よりも高い触媒活
性を有するデラフォサイト型の光触媒を提供することを
目的とする。The present invention has been made in view of the above problems, and an object of the present invention is to provide a delafossite-type photocatalyst having a higher catalytic activity in the visible light region than conventional ones.
【００１０】[0010]
【課題を解決するための手段】そのため、本発明は第一
に「一般式ＡＢＯ2（A：１種または２種以上の１価の金
属元素、Ｂ：１種または２種以上の３価の金属元素）で
表され、可視光により水を分解して、水素と酸素のうち
少なくとも一方を生成させる光触媒のうち、酸処理によ
り表面改質したことを特徴とする光触媒（請求項１）」
を提供する。Therefore, the present invention firstly provides a compound represented by the general formula ABO 2 (A: one or more monovalent metal elements, B: one or more trivalent metal elements) (A metal element), which is a photocatalyst characterized by surface modification by an acid treatment, among photocatalysts that decompose water by visible light to generate at least one of hydrogen and oxygen (claim 1) ”
I will provide a.
【００１１】また、本発明は第二に「可視光照射下にお
いて水を分解し、水素と酸素のうち少なくとも一方を生
成させる光触媒であり、酸処理により表面改質がなさ
れ、かつ化学式ＡＢＯ2（A：１価の単一金属元素または
複合金属元素、Ｂ：３価の単一金属元素または複合金属
元素）で表される粒子状の光触媒（請求項２）」を提供
する。The present invention also provides, secondly, a photocatalyst which decomposes water under irradiation with visible light to generate at least one of hydrogen and oxygen, has a surface modified by an acid treatment, and has a chemical formula of ABO 2 ( A: a monovalent single metal element or a composite metal element, and B: a trivalent single metal element or a composite metal element).
【００１２】また、本発明は第三に「可視光照射下にお
いて水を分解し、水素と酸素のうち少なくとも一方を生
成させる光触媒であり、酸処理により表面改質した光触
媒前駆体（粒子状物質）を、化学式ＡＢＯ2（A：１価の
単一金属元素または複合金属元素、Ｂ：３価の単一金属
元素または複合金属元素）で表される微粒子状物質に微
細化してなる光触媒（請求項３）」を提供する。Further, the present invention provides a photocatalyst which decomposes water under visible light irradiation to generate at least one of hydrogen and oxygen, and comprises a photocatalyst precursor (particulate matter ) Is converted to fine particles represented by the chemical formula ABO 2 (A: monovalent single metal element or composite metal element, B: trivalent single metal element or composite metal element) to form a photocatalyst (claim Item 3) "is provided.
【００１３】また、本発明は第四に「前記化学式におけ
るAがＣｕであることを特徴とする請求項１〜３のいず
れかに記載の光触媒（請求項４）」を提供する。また、
本発明は第五に「前記化学式におけるBがＣｒ,Ｍｎ,Ｆ
ｅ,Ｃｏ,Ｇａからなる元素群から選択された単一金属元
素または複合金属元素であることを特徴とする請求項１
〜４のいずれかに記載の光触媒（請求項５）」を提供す
る。The present invention fourthly provides a "photocatalyst according to any one of claims 1 to 3, wherein A in the above chemical formula is Cu (claim 4)." Also,
The present invention is a fifth aspect of the present invention wherein B in the above chemical formula is Cr, Mn, F
2. A single metal element or a composite metal element selected from the group consisting of e, Co, and Ga.
The photocatalyst according to any one of (1) to (4) (claim 5) is provided.
【００１４】また、本発明は第六に「粒径が0.1〜10ミクロ
ン（好ましくは、0.1〜1ミクロン）であることを特徴とする
請求項１〜５のいずれかに記載の光触媒（請求項６）」
を提供する。The present invention provides a photocatalyst according to any one of claims 1 to 5, characterized in that the particle size is 0.1 to 10 microns (preferably 0.1 to 1 micron). 6) "
I will provide a.
【００１５】[0015]
【発明の実施の形態】本発明者らが鋭意検討した結果、
前記化学式ａｂＯ2で表され、デラフォサイト（Delafos
site）型の結晶構造を有するとされる微粒子状物質から
なる従来の光触媒において、金属元素ａが１価以外の価
数をとらない元素であれば特に問題はないが、金属元素
ａが１価以外の価数をとることができる元素の場合に、
光触媒の触媒活性がかなり低いことが判った。BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies by the present inventors,
The chemical formula is represented by abO 2 and is represented by Delafosite (Delafos).
In a conventional photocatalyst comprising a particulate material having a site-type crystal structure, there is no particular problem as long as the metal element a does not take a valence other than monovalent, but the metal element a is monovalent. In the case of an element that can take a valence other than
It was found that the catalytic activity of the photocatalyst was considerably low.
【００１６】そして、本発明者らは、金属元素ａが１価
以外の価数をとることができる元素の場合には、酸化反
応が起こらないように不活性ガス雰囲気中で合成したと
しても、原料に吸着した水の影響等により合成される光
触媒または光触媒前駆体の表面付近では価数変化が発生
して完全なデラフォサイト型の結晶構造とはならず、そ
の結果、製造される光触媒の触媒活性が阻害されるおそ
れが高いことを見いだした。When the metal element a is an element capable of taking a valence other than monovalent, the present inventors have proposed that even if the metal element a is synthesized in an inert gas atmosphere so as not to cause an oxidation reaction, In the vicinity of the surface of the photocatalyst or photocatalyst precursor synthesized due to the influence of water adsorbed on the raw material, a valence change occurs, and a complete delafossite-type crystal structure is not obtained. It has been found that the catalyst activity is likely to be inhibited.
【００１７】さらに、本発明者らは、前記合成された光
触媒または光触媒前駆体を酸（特に硝酸が好ましい）で
処理して表面改質することにより、最終的に製造される
光触媒の可視光領域における触媒活性を従来よりも大き
く向上させることができることを見出して、本発明をな
すにいたった。即ち、光触媒または光触媒前駆体の合成
時に、原料に吸着した水の影響等により光触媒または前
駆体の表面付近で価数変化が発生した場合でも、合成さ
れた光触媒または前駆体を酸処理することで光触媒また
は前駆体の表面を溶解し、光触媒内部または前駆体内部
の価数変化を起こしていない面を露出させれば、最終的
に製造される光触媒の触媒活性が阻害されることはな
い。The present inventors further treat the synthesized photocatalyst or photocatalyst precursor with an acid (particularly, nitric acid is preferred) to modify the surface thereof, thereby obtaining a visible light region of a finally produced photocatalyst. The present inventors have found that the catalyst activity can be greatly improved as compared with the prior art, and have accomplished the present invention. That is, at the time of synthesis of the photocatalyst or photocatalyst precursor, even when a valence change occurs near the surface of the photocatalyst or precursor due to the influence of water adsorbed on the raw material, the synthesized photocatalyst or precursor is subjected to acid treatment. By dissolving the surface of the photocatalyst or the precursor and exposing the inside of the photocatalyst or the inside of the precursor where the valence does not change, the catalytic activity of the finally produced photocatalyst is not hindered.
【００１８】そこで、本発明（請求項１〜６）にかかる
可視光領域で触媒活性を有し、化学式ＡＢＯ2（A：１価
の単一金属元素または複合金属元素、Ｂ：３価の単一金
属元素または複合金属元素）で表される光触媒は、酸処
理により表面改質した光触媒とするか、或いは酸処理に
より表面改質した光触媒前駆体（粒子状物質）を、前記
化学式ＡＢＯ2で表される微粒子状物質に微細化してな
る光触媒とした。Therefore, according to the present invention (claims 1 to 6), it has a catalytic activity in the visible light region and has a chemical formula of ABO 2 (A: monovalent single metal element or composite metal element, B: trivalent monometallic element). The photocatalyst represented by the monometallic element or the composite metal element) is a photocatalyst whose surface has been modified by acid treatment, or a photocatalyst precursor (particulate matter) whose surface has been modified by acid treatment is represented by the chemical formula ABO 2 . The resulting photocatalyst was made into a fine particle material.
【００１９】そして、かかる構成を採用したので、本発
明（請求項１〜６）の光触媒は、可視光領域における触
媒活性を従来よりも大きく向上させることができる。な
お、１価の複合金属元素とは、１価の単一金属元素から
なる物質を１種類以上の異なる単一金属元素（１価）で
部分的に置換した物質の構成元素を概念化したものであ
り、同様に３価の複合金属元素とは、３価の単一金属元
素からなる物質を１種類以上の異なる単一金属元素（３
価）で部分的に置換した物質の構成元素を概念化したも
のである。Since such a configuration is employed, the photocatalyst of the present invention (claims 1 to 6) can greatly improve the catalytic activity in the visible light region as compared with the conventional one. The monovalent composite metal element is a conceptualization of a constituent element of a substance obtained by partially substituting a substance consisting of a monovalent single metal element with one or more different single metal elements (monovalent). Similarly, a trivalent composite metal element refers to a substance consisting of a trivalent single metal element as one or more different single metal elements (3
) Is a conceptualization of the constituent elements of a substance partially substituted with (valence).
【００２０】本発明にかかる前記化学式におけるAをＣ
ｕ元素とすると、可視光照射下において水を分解し、水
素と酸素の両方を同時に生成させることができるので好
ましい（請求項４）。即ち、水素と酸素の両方を同時に
生成させることができる光触媒においては、光照射によ
り生成されたホール（正孔）とエレクトロン（電子）が
それぞれ有効に水の分解反応に関与するので、触媒寿命
や触媒活性の低下が起こりにくく、触媒機能の安定性が
良好となるので好ましい。In the chemical formula according to the present invention, A is represented by C
The element u is preferable because water can be decomposed under visible light irradiation, and both hydrogen and oxygen can be generated simultaneously (claim 4). That is, in a photocatalyst capable of simultaneously generating both hydrogen and oxygen, holes (holes) and electrons (electrons) generated by light irradiation effectively participate in the decomposition reaction of water, respectively, so that the catalyst life and This is preferable because the catalyst activity hardly decreases and the stability of the catalyst function is improved.
【００２１】本発明にかかる前記化学式におけるBとし
ては、Ｃｒ,Ｍｎ,Ｆｅ,Ｃｏ,Ｇａからなる元素群から選
択された単一金属元素または複合金属元素が使用できる
（請求項５）。本発明にかかる光触媒の形状は、可視光
を有効に利用できるように、表面積の大きな微粒子（微
粒子サイズ0.1〜10ミクロン）とすることが好ましく、特に
好ましい微粒子サイズは0.1〜1ミクロンである（請求項
６）。As B in the chemical formula according to the present invention, a single metal element or a composite metal element selected from the group consisting of Cr, Mn, Fe, Co, and Ga can be used. The shape of the photocatalyst according to the present invention is preferably fine particles having a large surface area (fine particle size of 0.1 to 10 microns), and particularly preferable fine particle size is 0.1 to 1 micron so that visible light can be effectively used. Item 6).
【００２２】かかる微粒子サイズの光触媒は、粒子状の
光触媒または光触媒前駆体をボールミルや遊星ミルで粉
砕して、さらに微粒子化することにより得ることができ
る。なお、助触媒（例えばＰｔ、ＮｉＯ等）の担持等、
光触媒の製造において一般的に使用される修飾を本発明
にかかる光触媒についても行うことができる。さらに、
本発明にかかる水分解反応を行う際に使用する水は純水
に限らず、炭酸塩や炭酸水素塩等の塩類を混ぜた水を使
用してもよい。或いは、アルコールや銀イオン等の犠牲
試薬を使用して、水素または酸素のいずれか一方を生成
させてもよい。Such a photocatalyst having a fine particle size can be obtained by pulverizing a particulate photocatalyst or a photocatalyst precursor with a ball mill or a planetary mill and further reducing the particle size. In addition, supporting of a co-catalyst (for example, Pt, NiO, etc.)
Modifications commonly used in the production of photocatalysts can also be made to photocatalysts according to the present invention. further,
The water used when performing the water splitting reaction according to the present invention is not limited to pure water, and water mixed with salts such as carbonates and bicarbonates may be used. Alternatively, a sacrificial reagent such as alcohol or silver ions may be used to generate either hydrogen or oxygen.
【００２３】本発明の光触媒は、水の分解反応だけでな
く、他の化学反応（例えば、有機物の分解反応や貴金属
イオンの還元反応）にも適用可能である。以下、実施例
により本発明を具体的に説明するが、本発明はこれらに
限定されるものではない。The photocatalyst of the present invention can be applied to not only a water decomposition reaction but also other chemical reactions (for example, a decomposition reaction of an organic substance and a reduction reaction of a noble metal ion). Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited thereto.
【００２４】[0024]
【実施例１】本実施例の可視光領域で触媒活性を有する
光触媒は、粒子状の光触媒または光触媒前駆体を酸処理
して表面改質したものを、さらに微粒子状に粉砕した光
触媒（ＣｕＦｅＯ2）である。 （１）本実施例の光触媒を製造する方法 まず、Ｃｕ2ＯとＦｅ2Ｏ3を所定組成の比率にて混合
し、不活性ガス雰囲気中で焼成することにより（固相
法）、光触媒の前駆体（粒子状のＣｕＦｅＯX）を合成
した。Embodiment 1 The photocatalyst having catalytic activity in the visible light region of this embodiment is a photocatalyst (CuFeO 2) obtained by subjecting a particulate photocatalyst or a photocatalyst precursor to a surface modification by acid treatment and further pulverizing the photocatalyst into fine particles. ). (1) Method for Producing the Photocatalyst of the Example First, Cu 2 O and Fe 2 O 3 were mixed at a predetermined composition ratio and fired in an inert gas atmosphere (solid phase method) to obtain a photocatalyst. A precursor (particulate CuFeO x ) was synthesized.
【００２５】ここで、Ｃｕ2Ｏについては合成中に揮発
することを考慮し、理論量（化学量論比による量：2.36
g）のほぼ１０％増しで調合した。即ち、Ｃｕ2Ｏ:２．
６０ｇ、Ｆｅ2Ｏ3 ：２．６４ｇをそれぞれ秤量し、ア
ルミナボートに入れて、窒素雰囲気中で１０５０℃、１
０時間の焼成を行った。次に、得られた前駆体（粒子状
物質）２ｇを５Ｎ硝酸中で２０時間攪拌することによ
り、前駆体の酸処理を行った。The stoichiometric amount (amount based on stoichiometric ratio: 2.36) of Cu 2 O is considered in consideration of volatilization during the synthesis.
g) increased by almost 10%. That is, Cu 2 O: 2.
60 g and 2.64 g of Fe 2 O 3 were weighed and placed in an alumina boat at 1050 ° C. for 1 hour in a nitrogen atmosphere.
The firing was performed for 0 hours. Next, 2 g of the obtained precursor (particulate matter) was stirred in 5N nitric acid for 20 hours to perform an acid treatment of the precursor.
【００２６】次に、酸処理による表面改質を行った前駆
体を濾過して回収し、これを純水洗浄してから風乾させ
た。その後、前駆体を乳鉢で径１０μｍ以下の微粒子に
粉砕することにより、本実施例の光触媒（微粒子状のＣ
ｕＦｅＯ2）を製造した。なお、製造した光触媒微粒子
を粉末Ｘ線回折により同定したところ、デラフォサイト
構造を有するＣｕＦｅＯ2であり、酸処理による構造変
化は見られなかった。 （２）触媒活性の評価 製造した光触媒の触媒活性の評価は、閉鎖循環系触媒反
応装置を使用し、以下に示すように、反応溶液として純
水を用いて水素及び酸素を生成させることにより行っ
た。Next, the precursor whose surface was modified by acid treatment was recovered by filtration, washed with pure water, and air-dried. Thereafter, the precursor is pulverized in a mortar into fine particles having a diameter of 10 μm or less, whereby the photocatalyst (fine particle C
uFeO 2 ). When the produced photocatalyst fine particles were identified by powder X-ray diffraction, they were CuFeO 2 having a delafossite structure, and no structural change due to acid treatment was observed. (2) Evaluation of catalytic activity The catalytic activity of the produced photocatalyst was evaluated by using a closed-circulation catalytic reactor and generating hydrogen and oxygen using pure water as a reaction solution as shown below. Was.
【００２７】まず、製造した光触媒０．４gを純水３５
０mｌ中に入れて、マグネチックスターラーで攪拌しな
がら外部から光を照射した。この際、光源として５００
Ｗキセノンランプ、反応管としてパイレックスガラス製
の管を用いた。また、フィルターにより波長４２０ｎｍ
以下の光をカットして光照射を行なった。次に、生成し
た水素、酸素の測定（検出及び定量）をガスクロマトグ
ラフィーにより行った。測定の結果、水素及び酸素の発
生が認められ、触媒活性は水素：５μmol/h、酸素２μm
ol/hであった。First, 0.4 g of the produced photocatalyst was mixed with 35 parts of pure water.
The mixture was placed in 0 ml, and irradiated with light from the outside while stirring with a magnetic stirrer. At this time, 500
A tube made of Pyrex glass was used as a W xenon lamp and a reaction tube. In addition, wavelength 420nm by filter
The following light was cut and light irradiation was performed. Next, measurement (detection and quantification) of the generated hydrogen and oxygen was performed by gas chromatography. As a result of the measurement, generation of hydrogen and oxygen was recognized, and the catalytic activity was 5 μmol / h for hydrogen and 2 μm for oxygen.
ol / h.
【００２８】前述したように、本実施例の光触媒は、粒
子状の光触媒前駆体を微粒子状に粉砕する前に、前駆体
を酸処理して表面改質しているが、比較のために前駆体
の酸処理を行わないで得られた従来の光触媒についてそ
の触媒活性を測定したところ、水素：０．７μmol/h、
酸素：０．５μmol/hであった。即ち、本実施例の光触
媒は、従来の光触媒よりも可視光領域でかなり高い触媒
活性を有することが確認された。As described above, in the photocatalyst of this embodiment, the surface of the photocatalyst precursor is modified by acid treatment before the photocatalyst precursor is pulverized into fine particles. When the catalytic activity of the conventional photocatalyst obtained without performing acid treatment of the body was measured, hydrogen: 0.7 μmol / h,
Oxygen: 0.5 μmol / h. That is, it was confirmed that the photocatalyst of this example had a considerably higher catalytic activity in the visible light region than the conventional photocatalyst.
【００２９】[0029]
【実施例２】本実施例の可視光領域で触媒活性を有する
光触媒は、粒子状の光触媒前駆体を酸処理して表面改質
したものを微粒子状に粉砕してなる光触媒（ＣｕＧａＯ
2）である。 （１）本実施例の光触媒を製造する方法 まず、Ｃｕ2ＯとＧａ2Ｏ3を所定組成の比率にて混合
し、不活性ガス雰囲気中で焼成することにより（固相
法）、光触媒の前駆体（粒子状のＣｕＧａＯX）を合成
した。Embodiment 2 The photocatalyst having catalytic activity in the visible light region of this embodiment is a photocatalyst (CuGaOO) obtained by pulverizing a particulate photocatalyst precursor which has been surface-modified by acid treatment into fine particles.
2 ). (1) Method for Producing the Photocatalyst of the Example First, Cu 2 O and Ga 2 O 3 are mixed at a predetermined composition ratio and fired in an inert gas atmosphere (solid phase method) to obtain a photocatalyst. A precursor (particulate CuGaO x ) was synthesized.
【００３０】ここで、Ｃｕ2Ｏについては合成中に揮発
することを考慮し、理論量（化学量論比による量：2.16
g）の１０％増しで調合した。即ち、Ｃｕ2Ｏ:２．３７
ｇ、Ｇａ2Ｏ3 ：２．８４ｇをそれぞれ秤量し、アルミ
ナボートに入れて、窒素雰囲気中で１０５０℃、１０時
間の焼成を行った。次に、得られた前駆体（粒子状物
質）２ｇを５Ｎ硝酸中で２０時間攪拌することにより、
前駆体の酸処理を行った。Here, considering that Cu 2 O is volatilized during the synthesis, a stoichiometric amount (amount based on stoichiometric ratio: 2.16)
g) was increased by 10%. That is, Cu 2 O: 2.37
g and 2.84 g of Ga 2 O 3 were weighed, placed in an alumina boat, and fired at 1050 ° C. for 10 hours in a nitrogen atmosphere. Next, by stirring 2 g of the obtained precursor (particulate matter) in 5 N nitric acid for 20 hours,
The precursor was acid treated.
【００３１】次に、酸処理による表面改質を行った前駆
体を濾過して回収し、これを純水洗浄してから風乾させ
た。その後、前駆体を乳鉢で径１０μｍ以下の微粒子に
粉砕することにより、本実施例の光触媒（微粒子状のＣ
ｕＧａＯ2）を製造した。なお、製造した光触媒微粒子
を粉末Ｘ線回折により同定したところ、デラフォサイト
構造を有するＣｕＧａＯ2であり、酸処理による構造変
化は見られなかった。 （２）触媒活性の評価 実施例１と同様にして触媒活性の評価を行ったところ、
本実施例の光触媒は、従来の光触媒（前駆体の表面改質
を行わないもの）よりも可視光領域でかなり高い触媒活
性を有することが確認された。Next, the precursor whose surface was modified by acid treatment was recovered by filtration, washed with pure water, and air-dried. Thereafter, the precursor is pulverized in a mortar into fine particles having a diameter of 10 μm or less, whereby the photocatalyst (fine particle C
uGaO 2 ). When the produced photocatalyst fine particles were identified by powder X-ray diffraction, they were CuGaO 2 having a delafossite structure, and no structural change due to acid treatment was observed. (2) Evaluation of catalytic activity When the catalytic activity was evaluated in the same manner as in Example 1,
It was confirmed that the photocatalyst of this example had a considerably higher catalytic activity in the visible light region than the conventional photocatalyst (which does not modify the surface of the precursor).
【００３２】以上の実施例では、微粒子状のＣｕＧａＯ
2、ＣｕＦｅＯ2について説明したが、これ以外にも、微
粒子状のＣｕＣｒＯ2、ＣｕＭｎＯ2、ＣｕＣｏＯ2につ
いても同様に製造して、得られた各光触媒をそれぞれ評
価したところ、従来の光触媒（前駆体の表面改質を行わ
ないもの）よりも可視光領域でかなり高い触媒活性を有
することが確認された。In the above embodiment, the fine particle CuGaO
2 and CuFeO 2 , but in addition to the above, fine particles of CuCrO 2 , CuMnO 2 , and CuCoO 2 were produced in the same manner, and the obtained photocatalysts were evaluated. (Having no surface modification) has a significantly higher catalytic activity in the visible light region.
【００３３】[0033]
【発明の効果】以上説明した通り、本発明（請求項１〜
６）の光触媒は、可視光領域において従来よりも高い触
媒活性を有する。即ち、本発明（請求項１〜６）にかか
る可視光領域で触媒活性を有する光触媒は、酸処理して
表面を改質してなるので、酸処理による表面改質を行わ
ない従来の光触媒よりも高い触媒活性を有する。As described above, the present invention (Claims 1 to 5)
The photocatalyst of 6) has a higher catalytic activity in the visible light region than before. That is, since the photocatalyst having catalytic activity in the visible light region according to the present invention (claims 1 to 6) is obtained by modifying the surface by an acid treatment, the photocatalyst does not perform the surface modification by the acid treatment. Also have high catalytic activity.
【００３４】本発明にかかる前記化学式におけるAをＣ
ｕ元素とすると、可視光の照射により水を分解して、水
素と酸素の両方を同時に生成させることができる（生成
された正孔と電子がそれぞれ有効に水の分解反応に関与
する）ので、触媒寿命や触媒活性の低下が起こりにく
く、触媒機能の安定性が良好となる（請求項４）。本発
明にかかる前記化学式におけるBとして、Ｃｒ,Ｍｎ,Ｆ
ｅ,Ｃｏ,Ｇａからなる元素群から選択された単一金属元
素または複合金属元素を使用すれば、従来の光触媒（前
駆体の表面改質を行わないもの）よりも可視光領域でか
なり高い触媒活性を有する光触媒が得られる（請求項
５）。In the chemical formula according to the present invention, A is represented by C
When the element is u, water can be decomposed by irradiation with visible light to generate both hydrogen and oxygen at the same time (the generated holes and electrons are each effectively involved in the decomposition reaction of water). The catalyst life and catalyst activity are not easily reduced, and the stability of the catalyst function is improved. As B in the chemical formula according to the present invention, Cr, Mn, F
When a single metal element or a composite metal element selected from the group consisting of e, Co, and Ga is used, the catalyst is considerably higher in the visible light region than the conventional photocatalyst (which does not modify the surface of the precursor). An active photocatalyst is obtained (claim 5).
【００３５】本発明の光触媒の形状を径0.1〜10ミクロン
（好ましくは、0.1〜1ミクロン）の微粒子状とすると、光触
媒の表面積が大きくなって、照射される可視光を有効に
利用することができる（請求項６）。 以上When the photocatalyst of the present invention is formed into fine particles having a diameter of 0.1 to 10 μm (preferably 0.1 to 1 μm), the surface area of the photocatalyst becomes large, and the visible light to be irradiated can be effectively used. (Claim 6). that's all
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 ＦＩ Ｂ０１Ｊ 23/86 Ｂ０１Ｊ 23/82 Ｍ Ｃ０１Ｂ 3/04 23/84 ３１１Ｍ ──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. 6 Identification code FI B01J 23/86 B01J 23/82 M C01B 3/04 23/84 311M
Claims (6)
の１価の金属元素、Ｂ：１種または２種以上の３価の金
属元素）で表され、可視光により水を分解して、水素と
酸素のうち少なくとも一方を生成させる光触媒のうち、
酸処理により表面改質したことを特徴とする光触媒。1. A compound represented by the general formula ABO 2 (A: one or more monovalent metal elements, B: one or more trivalent metal elements), and decomposes water by visible light And among the photocatalysts that generate at least one of hydrogen and oxygen,
A photocatalyst having a surface modified by acid treatment.
と酸素のうち少なくとも一方を生成させる光触媒であ
り、酸処理により表面改質がなされ、かつ化学式ＡＢＯ
2（A：１価の単一金属元素または複合金属元素、Ｂ：３
価の単一金属元素または複合金属元素）で表される粒子
状の光触媒。2. A photocatalyst which decomposes water under irradiation with visible light to generate at least one of hydrogen and oxygen, has a surface modified by acid treatment, and has a chemical formula of ABO
2 (A: monovalent single metal element or composite metal element, B: 3
Particulate photocatalyst represented by the following formula:
と酸素のうち少なくとも一方を生成させる光触媒であ
り、酸処理により表面改質した光触媒前駆体（粒子状物
質）を、化学式ＡＢＯ2（A：１価の単一金属元素または
複合金属元素、Ｂ：３価の単一金属元素または複合金属
元素）で表される微粒子状物質に微細化してなる光触
媒。3. A photocatalyst that decomposes water under irradiation with visible light to generate at least one of hydrogen and oxygen. A photocatalyst precursor (particulate matter) whose surface has been modified by acid treatment is converted to a chemical formula of ABO 2 ( A: a photocatalyst that is finely divided into fine particles represented by the following formula: A: a monovalent single metal element or a composite metal element;
を特徴とする請求項１〜３のいずれかに記載の光触媒。4. The photocatalyst according to claim 1, wherein A in the chemical formula is Cu.
Ｃｏ,Ｇａからなる元素群から選択された単一金属元素
または複合金属元素であることを特徴とする請求項１〜
４のいずれかに記載の光触媒。5. In the above chemical formula, B is Cr, Mn, Fe,
A single metal element or a composite metal element selected from the group consisting of Co and Ga.
5. The photocatalyst according to any one of 4.
1ミクロン）であることを特徴とする請求項１〜５のいずれ
かに記載の光触媒。6. A particle size of 0.1 to 10 microns (preferably 0.1 to 10 microns).
The photocatalyst according to any one of claims 1 to 5, wherein the photocatalyst is 1 micron.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10019319A JPH11216364A (en) | 1998-01-30 | 1998-01-30 | Photocatalyst |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10019319A JPH11216364A (en) | 1998-01-30 | 1998-01-30 | Photocatalyst |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11216364A true JPH11216364A (en) | 1999-08-10 |
Family
ID=11996097
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10019319A Pending JPH11216364A (en) | 1998-01-30 | 1998-01-30 | Photocatalyst |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11216364A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007185605A (en) * | 2006-01-13 | 2007-07-26 | Univ Of Tokyo | Promoter for photocatalyst and photocatalytic material |
| JP2008156130A (en) * | 2006-12-20 | 2008-07-10 | Mitsui Mining & Smelting Co Ltd | Delafossite type oxide, method for manufacturing the same and exhaust gas purification catalyst |
| JP2016521234A (en) * | 2013-04-02 | 2016-07-21 | ビーワイディー カンパニー リミテッドＢｙｄ Ｃｏｍｐａｎｙ Ｌｉｍｉｔｅｄ | Metal compound, method for producing the metal compound, and selective metallization of the substrate surface with the metal compound |
-
1998
- 1998-01-30 JP JP10019319A patent/JPH11216364A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007185605A (en) * | 2006-01-13 | 2007-07-26 | Univ Of Tokyo | Promoter for photocatalyst and photocatalytic material |
| JP4714873B2 (en) * | 2006-01-13 | 2011-06-29 | 国立大学法人 東京大学 | Cocatalyst for photocatalyst and photocatalyst material |
| JP2008156130A (en) * | 2006-12-20 | 2008-07-10 | Mitsui Mining & Smelting Co Ltd | Delafossite type oxide, method for manufacturing the same and exhaust gas purification catalyst |
| JP2016521234A (en) * | 2013-04-02 | 2016-07-21 | ビーワイディー カンパニー リミテッドＢｙｄ Ｃｏｍｐａｎｙ Ｌｉｍｉｔｅｄ | Metal compound, method for producing the metal compound, and selective metallization of the substrate surface with the metal compound |
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