JP2002159863A - Synergistic photocatalyst - Google Patents
Synergistic photocatalystInfo
- Publication number
- JP2002159863A JP2002159863A JP2000362682A JP2000362682A JP2002159863A JP 2002159863 A JP2002159863 A JP 2002159863A JP 2000362682 A JP2000362682 A JP 2000362682A JP 2000362682 A JP2000362682 A JP 2000362682A JP 2002159863 A JP2002159863 A JP 2002159863A
- Authority
- JP
- Japan
- Prior art keywords
- photocatalyst
- photocatalytic
- active
- synergistic effect
- titanium oxide
- 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 62
- 230000002195 synergetic effect Effects 0.000 title claims abstract description 18
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 32
- 230000001699 photocatalysis Effects 0.000 claims abstract description 24
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims abstract description 24
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 10
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims abstract description 10
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims 2
- 239000000463 material Substances 0.000 abstract description 3
- 239000003054 catalyst Substances 0.000 abstract description 2
- 230000002708 enhancing effect Effects 0.000 abstract 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 16
- 238000006243 chemical reaction Methods 0.000 description 16
- 229910052760 oxygen Inorganic materials 0.000 description 16
- 239000001301 oxygen Substances 0.000 description 16
- 239000000126 substance Substances 0.000 description 12
- 239000010408 film Substances 0.000 description 10
- 239000011521 glass Substances 0.000 description 10
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 9
- 241000233866 Fungi Species 0.000 description 8
- 229910052739 hydrogen Inorganic materials 0.000 description 8
- 239000001257 hydrogen Substances 0.000 description 8
- 239000000243 solution Substances 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 6
- 238000000354 decomposition reaction Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 230000006870 function Effects 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 229910000859 α-Fe Inorganic materials 0.000 description 5
- 241000894006 Bacteria Species 0.000 description 4
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 4
- 230000000844 anti-bacterial effect Effects 0.000 description 4
- 230000003373 anti-fouling effect Effects 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- 238000000746 purification Methods 0.000 description 4
- 239000010936 titanium Substances 0.000 description 4
- VXUYXOFXAQZZMF-UHFFFAOYSA-N titanium(IV) isopropoxide Chemical compound CC(C)O[Ti](OC(C)C)(OC(C)C)OC(C)C VXUYXOFXAQZZMF-UHFFFAOYSA-N 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- 230000001877 deodorizing effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 239000005357 flat glass Substances 0.000 description 2
- 230000036541 health Effects 0.000 description 2
- TUJKJAMUKRIRHC-UHFFFAOYSA-N hydroxyl Chemical compound [OH] TUJKJAMUKRIRHC-UHFFFAOYSA-N 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 238000013032 photocatalytic reaction Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000002441 reversible effect Effects 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 102100032566 Carbonic anhydrase-related protein 10 Human genes 0.000 description 1
- 101000867836 Homo sapiens Carbonic anhydrase-related protein 10 Proteins 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000002156 adsorbate Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 230000000172 allergic effect Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000010420 art technique Methods 0.000 description 1
- 208000010668 atopic eczema Diseases 0.000 description 1
- 230000001580 bacterial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 210000004027 cell Anatomy 0.000 description 1
- 210000000170 cell membrane Anatomy 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 239000002781 deodorant agent Substances 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 201000010099 disease Diseases 0.000 description 1
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 208000015181 infectious disease Diseases 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- MVFCKEFYUDZOCX-UHFFFAOYSA-N iron(2+);dinitrate Chemical compound [Fe+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MVFCKEFYUDZOCX-UHFFFAOYSA-N 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- SOQBVABWOPYFQZ-UHFFFAOYSA-N oxygen(2-);titanium(4+) Chemical class [O-2].[O-2].[Ti+4] SOQBVABWOPYFQZ-UHFFFAOYSA-N 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000007146 photocatalysis Methods 0.000 description 1
- 229910000028 potassium bicarbonate Inorganic materials 0.000 description 1
- 235000015497 potassium bicarbonate Nutrition 0.000 description 1
- 239000011736 potassium bicarbonate Substances 0.000 description 1
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 230000027756 respiratory electron transport chain Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000035807 sensation Effects 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000006557 surface reaction Methods 0.000 description 1
- 208000024891 symptom Diseases 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- -1 titanium alkoxide Chemical class 0.000 description 1
- 230000001960 triggered effect Effects 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
Landscapes
- Disinfection, Sterilisation Or Deodorisation Of Air (AREA)
- Catalysts (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】身近な生活空間の環境を改善
する新技術への期待が高まっている。健康管理を目的と
する対策、あるいは高齢化社会にともなう安全な環境造
りなどで居住空間、医療施設、乗物空間等での空気の質
が問題視され始めている。例えば一般家庭の室内、ビル
内事務室、学校、デパート、レストラン、食品加工所、
厨房、病院内の手術室、入院室、待合室、地下鉄、電
車、旅客機、バス、自動車、エレベーターなど人体への
影響が問題となる場所に於いて、簡便で安価そして穏や
かに空気環境を良くする技術が求められている。BACKGROUND OF THE INVENTION Expectations for new technologies for improving the environment of familiar living spaces are increasing. The quality of air in living spaces, medical facilities, vehicle spaces, etc. has begun to be viewed as a problem due to measures for health management or the creation of a safe environment accompanying an aging society. For example, indoors of general households, offices in buildings, schools, department stores, restaurants, food processing plants,
Technology to improve the air environment easily, cheaply and gently in places where effects on the human body such as kitchens, hospital operating rooms, hospital admission rooms, waiting rooms, subways, trains, passenger planes, buses, automobiles, and elevators pose a problem. Is required.
【０００２】抗菌の分野では食品を取り扱う場での菌増
殖の抑制対策は急務である。厚生省は菌類の新たな環境
規制法案を定める方向にある。具体的にはまず自主規制
を促すため１９９９年４月より米国総合衛生管理製造過
程ＨＡＣＣＰ（Ｈazard Ａnalysis Ｃritical Ｃontrol
Ｐoint）の導入により日本全国の食品製造現場での菌
類の測定検査が行なわれるようになった。従って菌類の
除去対策も新たに必要になってきている。一般に外気と
の流通が乏しい密閉空間では様々な菌類が増殖蔓延する
現象が起きる。これら菌類の濃度はごく微量であるが人
体への影響は大きく、アレルギー症状や様々な病気を引
き起こし、感染もする。これらの菌類を低減する技術は
今後広く普及してゆくことが考えられる。[0002] In the field of antibacterial activity, measures to control bacterial growth in places where food is handled are urgently needed. The Ministry of Health and Welfare is in the process of drafting a new environmental regulation bill for fungi. Specifically, first of all, in April 1999, the United States comprehensive hygiene management manufacturing process HACCP (Hazard Analysis Critical Control) to promote self-regulation.
With the introduction of Point, the measurement and inspection of fungi at food production sites throughout Japan have come to be carried out. Therefore, a new measure for removing fungi is also needed. Generally, a phenomenon in which various fungi proliferate and spread occurs in an enclosed space where circulation with outside air is poor. Although the concentration of these fungi is very small, it has a great effect on the human body, causing allergic symptoms, various diseases, and infection. It is considered that the technology for reducing these fungi will be widely spread in the future.
【０００３】悪臭分子はその種類によってppm，ppb，pp
tあるいはそれ以下の濃度領域に於いて室内に蔓延し不
快な感覚を与える。また空気中には必ずしも不快臭はな
いが比較的炭素数の大きい油性の有機物が拡散してお
り、いろいろな物体の表面に付着して空気中のほこりを
吸着する結果、次第に表面が汚れてくる。これらが問題
になる場では悪臭を除去する脱臭技術、あるいは汚れを
防止する防汚技術が求められる。[0003] Odor molecules are classified into ppm, ppb, pp
It spreads indoors and gives an unpleasant sensation in the concentration range of t or lower. In addition, oily organic substances with a relatively high carbon number are diffused in the air, but they do not necessarily have an unpleasant odor.As a result, they adhere to the surface of various objects and adsorb the dust in the air, so that the surface gradually becomes dirty. . Where these are problems, a deodorizing technique for removing a bad smell or an antifouling technique for preventing dirt is required.
【０００４】[0004]
【従来の技術】室内空気中に浮遊する微量有害物質の除
去対策にはこれまで特殊な専用装置を必要とする技術が
実用化されてきた。例えばエアコン、空気清浄機、ある
いは病院で使われる専用空調機等である。これらは専用
フィルターを使用して有害物質を捕らえるが、フィルタ
ーは一定時間使用後に吸着物で飽和するので交換や洗浄
をしなければならず常に定期管理が必要となる。最近は
エアコン、空気清浄機等のフィルターに光触媒を組み込
み、光触媒専用の光源ランプを内設して光触媒効果を付
加した空調機も実用化されているが、これも専用装置と
しての対策である。いずれにせよ、より簡便で定期管理
を必要としないメンテフリーな環境浄化方法が望まし
い。2. Description of the Related Art Techniques that require special dedicated devices have been put to practical use as measures for removing trace harmful substances floating in indoor air. For example, it is an air conditioner, an air purifier, or a dedicated air conditioner used in a hospital. These use a special filter to capture harmful substances, but the filter is saturated with the adsorbate after a certain period of use, so it must be replaced or washed, and regular management is always required. Recently, an air conditioner incorporating a photocatalyst in a filter of an air conditioner, an air purifier, or the like and a photocatalytic effect added by installing a light source lamp dedicated to the photocatalyst has been put into practical use, but this is also a measure as a dedicated device. In any case, a maintenance-free environmental purification method that is simpler and does not require periodic management is desirable.
【０００５】光触媒として最も多く利用される物質とな
った酸化チタンは、紫外領域波長の光子を吸収して電子
を価電子帯から伝導帯へ励起し、活性電子とホールのペ
アを発生すると同時に空気中の酸素や水分子がこれらと
接触して活性酸素やヒドロキシルラジカル等の酸化力の
強い活性種を生成する。活性種は菌の細胞膜を破壊し、
悪臭分子や汚れの原因となる有機分子を酸化分解して抗
菌、脱臭、防汚効果を発揮する。[0005] Titanium oxide, which has become the substance most frequently used as a photocatalyst, absorbs photons in the ultraviolet region to excite electrons from the valence band to the conduction band, thereby generating pairs of active electrons and holes, and simultaneously generating air. Oxygen and water molecules therein come into contact with these to generate active species having strong oxidizing power such as active oxygen and hydroxyl radicals. Active species destroy the cell membrane of the bacterium,
It oxidizes and decomposes organic molecules that cause odor molecules and stains, and exhibits antibacterial, deodorant, and antifouling effects.
【０００６】光触媒は抗菌、脱臭、防汚に代表される生
活環境浄化のみならずエネルギー問題の解決策としても
期待がかかっている。水を光エネルギーだけで室温で分
解してクリーンエネルギー源としての水素をえることで
ある。The photocatalyst is expected not only as a purification of living environment typified by antibacterial, deodorizing and antifouling, but also as a solution to energy problems. Decomposing water at room temperature with light energy alone to obtain hydrogen as a clean energy source.
【０００７】いずれにせよ現状は酸化チタン単独に勝る
光触媒物質系がなかなか提案されず実用化もされていな
い状況にあり、物質面からの効果向上が期待されてい
る。In any case, at present, a photocatalytic substance system superior to titanium oxide alone has not been proposed or put into practical use, and an improvement in the effect in terms of the substance is expected.
【０００８】[0008]
【発明が解決しようとする課題】健康的な居住空間をつ
くるための手段としては簡便でメンテフリーなものが好
ましい。そこで特殊な専用装置を使用することなく生活
環境を清浄化するのに役立つ実用製品に着目することが
肝要である。As means for creating a healthy living space, a simple and maintenance-free means is preferable. Therefore, it is important to focus on practical products that are useful for cleaning the living environment without using special dedicated devices.
【０００９】また、光触媒の機能を生かした環境浄化の
場合、既に酸化チタンを単独で使用した製品が実用化さ
れているが、光触媒の物質面での改良が今後の大きな課
題である。Further, in the case of environmental purification utilizing the function of a photocatalyst, a product using titanium oxide alone has already been put to practical use, but improvement in the material aspect of the photocatalyst is a major subject in the future.
【００１０】[0010]
【課題を解決するための手段】製品としての対象は日常
的に使用されているガラス製品に着目。ガラスと光触媒
とを組合せた物質系を造り、ガラスに接触する汚染物質
を光触媒作用で分解除去する。ガラスはそれ自体光を透
過するので光照射によって機能する光触媒の応用に便利
である。例えば窓ガラス、照明ランプ用ガラス管、ガラ
スカバー、その他生活用ガラス製品等で、各々の本来の
機能を損なうことなく、光触媒効果を付加するものとす
る。これらの製品は従来環境浄化の目的で実用化されて
いるものではないが広く生活に使われているところに特
長があり、それだけ普遍性が高い。例えば窓ガラスや照
明ランプなどは室内空気との接触が頻繁に起きる場所に
位置する場合が多く、また当然その目的からも光が照射
されるので光触媒との組合せが効果的となる。特に層状
の組み合せが効果的である。The object as a product focuses on a glass product that is used on a daily basis. A substance system combining a glass and a photocatalyst is made, and contaminants in contact with the glass are decomposed and removed by photocatalysis. Since glass itself transmits light, it is useful for photocatalytic applications that function by light irradiation. For example, a window glass, a glass tube for a lighting lamp, a glass cover, a glass product for daily use, and the like are provided with a photocatalytic effect without impairing their original functions. Although these products have not been practically used for the purpose of environmental purification, they are widely used in daily life, and have high universality. For example, a window glass, a lighting lamp, and the like are often located in a place where contact with indoor air frequently occurs, and naturally, light is irradiated for that purpose, so that a combination with a photocatalyst is effective. Particularly, a layered combination is effective.
【００１１】次に、本発明の本質的な内容を説明する。Next, the essential contents of the present invention will be described.
【００１２】まず、光触媒は光エネルギーを利用して室
温で化学反応を引き起こす特殊な触媒である。光触媒は
電子物性としては一種の半導体である。光触媒に光を照
射すると電子がバンドギャップを越えて価電子帯から伝
導帯へと励起され伝導帯に電子ｅ(-)、そして価電子帯
にホールｈ(+)を造りだす。この励起された電子を活性
電子と呼ぶ。この時バンドギャップのエネルギーよりも
大きいエネルギーを持つ光子（フォトン）、即ちそのエ
ネルギーに相当する波長よりも短い波長の光が光触媒に
当たると上記の励起が起きる。その臨界波長は酸化チタ
ンであれば約４００ｎｍである。フォトンの単位光照射
面積及び単位時間当たりの発生速度は励起できる波長範
囲の全光エネルギーに比例する。First, a photocatalyst is a special catalyst that causes a chemical reaction at room temperature using light energy. The photocatalyst is a kind of semiconductor in terms of electronic properties. When the photocatalyst is irradiated with light, electrons cross the band gap and are excited from the valence band to the conduction band, creating electrons e (−) in the conduction band and holes h (+) in the valence band. The excited electrons are called active electrons. At this time, when a photon (photon) having an energy larger than the energy of the band gap, that is, light having a wavelength shorter than the wavelength corresponding to the energy hits the photocatalyst, the above-described excitation occurs. Its critical wavelength is about 400 nm for titanium oxide. The unit photoirradiation area of a photon and the generation rate per unit time are proportional to the total light energy in the wavelength range that can be excited.
【００１３】この活性電子とホールとが引金となり種々
の活性種が光触媒表面に発生する。例えば、空気中の酸
素と活性電子が反応して活性酸素Ｏ2(-)を造る。また空
気中の水分とホールの反応で水が分解してプロトンＨ
(+)と酸素を発生する。更にこの二つの反応が連携して
過酸化水素Ｈ2Ｏ2や水酸ラジカル（ＯＨ・）などを造り
だす。Ｏ2(-)、Ｈ2Ｏ2、ＯＨ・などはいずれも酸化活性
が強く菌や有害物を酸化分解することができる。単位光
照射面積及び単位時間当たりのこれら活性種の発生速度
は活性電子やホールの発生速度に比例し、そして空気中
から光触媒表面に吸着する菌や有害分子の分解除去速度
もこれら活性種の発生速度に比例することになる。この
ように光エネルギー、光子、活性電子とホール、活性
種、菌や分子の分解除去は関連している。The active electrons and holes are triggered, and various active species are generated on the surface of the photocatalyst. For example, active oxygen reacts with oxygen in the air to produce active oxygen O 2 (−). In addition, water decomposes due to the reaction between water in the air and the holes, resulting in proton H
Generates (+) and oxygen. Further, these two reactions cooperate to produce hydrogen peroxide H 2 O 2 and hydroxyl radical (OH.). O 2 (−), H 2 O 2 , OH, etc. all have strong oxidizing activity and can oxidatively decompose bacteria and harmful substances. The generation rate of these active species per unit light irradiation area and unit time is proportional to the generation rate of active electrons and holes, and the rate of decomposition and removal of bacteria and harmful molecules adsorbed on the photocatalyst surface from the air is also the generation of these active species It will be proportional to speed. Thus, the decomposition and removal of light energy, photons, active electrons and holes, active species, bacteria and molecules are related.
【００１４】酸化チタンは代表的光触媒として既にいろ
いろな製品に利用されている。また、酸化チチンの中で
も特にアナターゼ型結晶構造を持つ電子移動型の酸化チ
タン薄膜が活性、即ち光触媒効果が高いことが知られて
いる（関連論文：Shinichi Ichikawa and Ryota Doi, T
hin Solid Films, vol.292, p.130，1997)。また、透明
なアナターゼ型酸化チタンを外表面に成膜したガラス管
を使用した蛍光ランプについては既に公開されている
（特開平10−116587号公報）。[0014] Titanium oxide is already used as a typical photocatalyst in various products. It is also known that among the oxidized titins, an electron-transfer-type titanium oxide thin film having an anatase-type crystal structure is particularly active, that is, has a high photocatalytic effect (related papers: Shinichi Ichikawa and Ryota Doi, T
hin Solid Films, vol.292, p.130, 1997). A fluorescent lamp using a glass tube having a transparent anatase-type titanium oxide film formed on the outer surface has already been disclosed (JP-A-10-116587).
【００１５】本発明は新しい原理に基づいた光触媒効果
の向上をもたらす物質系に関するものである。図１に原
理を示す。二つの異なる種類の光触媒（光触媒Ｉと光触
媒II)を物理的に接触させた構造設定で、Ｉは紫外領域
の光で活性化する酸化チタンに代表される紫外活性化型
の光触媒でIIは可視領域の光で活性化する可視活性化型
の光触媒である。[0015] The present invention relates to a substance system which improves the photocatalytic effect based on a new principle. FIG. 1 shows the principle. Two different types of photocatalysts (photocatalyst I and photocatalyst II) are in physical contact with each other. I is an ultraviolet activated photocatalyst represented by titanium oxide activated by light in the ultraviolet region, and II is visible. This is a visible activation type photocatalyst that is activated by light in the region.
【００１６】ＩとIIの接触により各々所定の波長範囲で
光励起された活性電子が相互の伝導帯へ移動出来るた
め、伝導帯に滞在する時間の分がホールとの再結合を抑
制し活性電子の寿命を長くするので、それだけ光触媒機
能を向上することになる。一方電子の光子励起によって
価電子帯に発生するホールについても同様のことが起
き、結果として相互の価電子帯の中での滞在寿命を伸ば
し、光触媒としての機能を向上する。The active electrons photoexcited in the respective predetermined wavelength ranges by the contact of I and II can move to each other's conduction band, so that the time spent in the conduction band suppresses recombination with holes, and the active electrons Since the life is extended, the photocatalytic function is improved accordingly. On the other hand, the same also occurs for holes generated in the valence band due to photon excitation of electrons, and as a result, the residence life in the mutual valence band is extended, and the function as a photocatalyst is improved.
【００１７】電子は価電子帯から伝導帯へ励起されてか
らある一定の存続寿命の後、即ちある一定時間伝導帯に
滞留した後に価電子帯に戻る。つまり活性電子の発生は
可逆的であり、その活性電子がなんらかの表面反応に使
用されなければ価電子帯のホールと再結合してしまう。
活性電子とホールは発生するときはペア（対）で発生
し、お互いが結合してもとに戻る。光触媒に光照射した
状態では常時このように活性電子が発生しては消滅して
いる。つまり、電子は光子によって励起されて価電子帯
からバンドギャップを超えて伝導帯へ入り、また価電子
帯へ戻る性質を持つ。ホールについても同様で、発生と
消滅を繰り返す。After the electrons are excited from the valence band to the conduction band, they return to the valence band after a certain lifetime, that is, after staying in the conduction band for a certain time. That is, the generation of active electrons is reversible, and if the active electrons are not used for any surface reaction, they recombine with holes in the valence band.
When an active electron and a hole are generated, they are generated as a pair, and return to the original state when they are combined. In a state where the photocatalyst is irradiated with light, active electrons are constantly generated and disappear. That is, electrons have the property of being excited by photons, entering the conduction band from the valence band across the band gap, and returning to the valence band. The same applies to the holes, and the generation and disappearance are repeated.
【００１８】従って活性電子が一つの光触媒からもう一
つの隣接した光触媒に移動する過程は、活性電子の寿命
を長く保つ効果をもたらす。活性電子の寿命が長くなる
と例えば空気中の酸素が光触媒に接触して活性酸素を生
成する確率が高くなる。即ち単位光触媒面積当たりの活
性酸素の密度が高くなり、それに比例して菌類や有害物
質の分解除去も向上することになる。次に各光触媒物質
に特有の性能との関連に於いて、活性電子とホールの移
動はその性能を伸ばすことができる。つまり特定の光触
媒反応（特定の活性種を造る反応、特定の活性種を含む
反応等)を促進するために特定の光触媒に活性電子やホ
ールを他の光触媒から移動集合させることにより光触媒
効果を高めることである。Therefore, the process of transferring active electrons from one photocatalyst to another adjacent photocatalyst has the effect of keeping the life of active electrons long. When the lifetime of active electrons is prolonged, for example, the probability that oxygen in the air contacts the photocatalyst to generate active oxygen increases. That is, the density of active oxygen per unit photocatalyst area is increased, and the decomposition and removal of fungi and harmful substances are improved in proportion thereto. The movement of active electrons and holes can then extend that performance in relation to the performance specific to each photocatalytic material. In other words, in order to promote a specific photocatalytic reaction (a reaction for producing a specific active species, a reaction including a specific active species, etc.), a photocatalytic effect is enhanced by transferring active electrons and holes to a specific photocatalyst from another photocatalyst. That is.
【００１９】二種の光触媒の選択であるが、例えば酸化
チタンの中でも活性の高いアナターゼ型酸化チタンＴｉ
Ｏ2（約４００ｎｍ以下の紫外光で励起）とアルファ型
酸化第二鉄α−Ｆｅ2Ｏ3（約５４０ｎｍ以下の可視光で
励起）とがある。お互いの伝導帯への活性電子の移動が
送信されて活性電子密度が大きくなれば、空気中の活性
酸素を始め各々の活性種の表面密度が高くなることであ
り、分解出来る有機物の処理効率が向上することにな
る。また水分解水素生成も促進されることになる。The choice of two types of photocatalysts is, for example, anatase-type titanium oxide Ti which is highly active among titanium oxides.
O 2 (excited by ultraviolet light of about 400 nm or less) and alpha-type ferric oxide α-Fe 2 O 3 (excited by visible light of about 540 nm or less). If the active electron density increases due to the transfer of active electrons to each other's conduction band, the surface density of each active species, including active oxygen in the air, increases, and the processing efficiency of organic substances that can be decomposed increases. Will be improved. In addition, generation of hydrocracked hydrogen is also promoted.
【００２０】酸素と活性電子から活性酸素が生成する反
応は次式（１）で表わされる。The reaction of generating active oxygen from oxygen and active electrons is represented by the following equation (1).
【００２１】 Ｏ2＋ｅ(-)＝Ｏ2(-) （１） 反応式（１）で空気中酸素Ｏ2が活性電子ｅ(-)と活性酸
素Ｏ2(-)を生成する。水の分解反応の例を式（２）に示
す。但し、一般に全ての光触媒反応に共通して言えるこ
とだが、各反応式は未だ正確に解明しておらず、ここで
示す反応式はこの限りではないことを注記しておく。O 2 + e (−) = O 2 (−) (1) In the reaction formula (1), oxygen O 2 in the air generates active electrons e (−) and active oxygen O 2 (−). Formula (2) shows an example of the water decomposition reaction. However, it should be noted that, although generally applicable to all photocatalytic reactions, each reaction formula has not been elucidated exactly yet, and the reaction formulas shown here are not limited thereto.
【００２２】 ２Ｈ2Ｏ＋４ｈ(+)＝４Ｈ(+)＋Ｏ2 （２） 上記（２）式は水Ｈ2Ｏとホールｈ(+)とが反応してプロ
トンＨ(+)と酸素Ｏ2を生成する反応を表わす。上記の反
応に関与するホールが二つの光触媒間を移動して水分解
を促すことになる。次に（１）の活性酸素とプロトンと
の反応から、これも活性種の一種である過酸化水素Ｈ2
Ｏ2を生成する反応を式（３）に示す。2H 2 O + 4h (+) = 4H (+) + O 2 (2) In the above formula (2), water H 2 O and hole h (+) react to form proton H (+) and oxygen O 2 . Represents the reaction produced. The holes involved in the above reaction move between the two photocatalysts to promote water splitting. Next, from the reaction between active oxygen and proton in (1), hydrogen peroxide H 2 , which is also a kind of active species,
The reaction producing O 2 is shown in equation (3).
【００２３】 ２Ｏ2(-)＋２Ｈ(+)＝Ｈ2Ｏ2＋Ｏ2 （３） 更に次の（４）式は水酸ラジカルＯＨ・を生成する反応
を表わす。2O 2 (−) + 2H (+) = H 2 O 2 + O 2 (3) Further, the following equation (4) represents a reaction for generating a hydroxyl radical OH.
【００２４】 Ｈ2Ｏ2＋Ｈ(+)＋ｅ(-)＝ＯＨ・＋Ｈ2Ｏ （４） 上記のように二つの光触媒の相乗効果が活性種類の増加
につながり、従って菌類、有害物の分解除去効果を高め
ることになる。H 2 O 2 + H (+) + e (−) = OH · + H 2 O (4) As described above, the synergistic effect of the two photocatalysts leads to an increase in the number of active species, and therefore, decomposition and removal of fungi and harmful substances. The effect will be enhanced.
【００２５】一方、水分解水素生成は、光触媒と対にな
る対極として例えば白金を用いて反応セルを組み水素分
子を発生する仕組みに於いて上記の相乗効果によって水
素生成速度を増加することが考えられる。（２）式に示
される水分解で得られるプロトンから水素分子が造られ
る反応を（５）式に示す。On the other hand, the generation of hydrogen splitting hydrogen is considered to increase the hydrogen generation rate by the above synergistic effect in a mechanism in which a reaction cell is assembled using, for example, platinum as a counter electrode paired with a photocatalyst to generate hydrogen molecules. Can be The reaction in which a hydrogen molecule is formed from the proton obtained by the water splitting shown in the formula (2) is shown in the formula (5).
【００２６】 ２Ｈ(+)＋２ｅ(-)＝Ｈ2 （５） 水素生成の装置については文献でも紹介している〔Ｓhi
nichi Ｉchikawa andＲyota Ｄoi, Ｃatalysis Ｔoday,
27，271（1996）〕。2H (+) + 2e (−) = H 2 (5) An apparatus for generating hydrogen is also introduced in the literature [Shi.
nichi Ichikawa and Ryota Doi, Catalysis Today,
27, 271 (1996)].
【００２７】[0027]
【発明の実施の形態】図２に試作サンプルの構造概念を
示す。基板に伝導性ガラスを使用した。光触媒Ｉをアナ
ターゼ型酸化チタン、光触媒IIをアルファ型酸化第二鉄
とした。酸化チタンの成膜はゾル・ゲル法で行なった。
即ち、チタンのアルコキシドの一種であるチタンテトラ
イソプロポキシド〔Ｔｉ(Ｏ−ｉ−Ｃ3Ｈ7)4〕とアルコ
ールを混合した溶液に酸とアルコールの混合した溶液を
加えてチタンテトライソプロポキシドの加水分解を行な
い、チタンのゾル液とした。FIG. 2 shows the concept of the structure of a prototype sample. Conductive glass was used for the substrate. Photocatalyst I was anatase type titanium oxide, and photocatalyst II was alpha type ferric oxide. The titanium oxide film was formed by a sol-gel method.
That is, a solution in which an acid and an alcohol are mixed is added to a solution in which titanium tetraisopropoxide [Ti (O-i-C 3 H 7 ) 4 ], which is a kind of titanium alkoxide, and an alcohol are mixed, and titanium tetraisopropoxide is added. Was hydrolyzed to obtain a titanium sol solution.
【００２８】次に、このゾル液を基板に成膜し、空気焼
成することにより透明でアナターゼ型結晶構造の酸化チ
タンを成膜できた。結晶構造はエックス線回析で確認し
た。Next, a film of this sol solution was formed on a substrate and calcined with air, thereby forming a transparent titanium oxide film having an anatase crystal structure. The crystal structure was confirmed by X-ray diffraction.
【００２９】次に、上記酸化チタン膜の上にα−Ｆｅ2
Ｏ3を形成した。水和硝酸鉄をアルコールに溶解した溶
液をｐＨ調整して得た溶液を酸化チタン膜の上に成膜
し、空気焼成した。結晶構造はエックス線回析で確認し
た。Next, α-Fe 2 was deposited on the titanium oxide film.
O 3 was formed. A solution obtained by adjusting the pH of a solution in which hydrated iron nitrate was dissolved in alcohol was formed on a titanium oxide film, and calcined in air. The crystal structure was confirmed by X-ray diffraction.
【００３０】このようにして形成されたサンプル（Ｔｉ
Ｏ2＋α−Ｆｅ2Ｏ3）と比較するため、各々ＴｉＯ2のみ
のサンプルとα−Ｆｅ2Ｏ3のみのサンプルとを作製準備
した。これらのサンプルの光触媒性能を測定するために
上記に説明した白金電極を対極とし重炭酸カリウムの電
解質溶液を含む溶液相内に設置して、サンプルに照射さ
れる光源をキセノンランプとし、各サンプルと白金電極
との間にバイアス電圧を付加出来る仕組を設定してバイ
アスをゼロから次第に大きくする時に得られる光電流を
測定した。光電流の大小は光子の照射から得られる活性
電子の数の大小を現わす。バイアス電圧は光励起された
活性電子を外部へ取り出し易くするために付加するもの
で各光触媒に固有の潜在的性能を観察し易くする目的
と、バイアスをかけること自体が光触媒性能を向上する
という目的もある。The thus formed sample (Ti
O 2 + α-Fe 2 O 3 ), a sample containing only TiO 2 and a sample containing only α-Fe 2 O 3 were prepared and prepared. In order to measure the photocatalytic performance of these samples, the above-described platinum electrode was placed in a solution phase containing an electrolyte solution of potassium bicarbonate as a counter electrode, and a xenon lamp was used as a light source for irradiating the samples. A mechanism capable of applying a bias voltage to a platinum electrode was set, and the photocurrent obtained when the bias was gradually increased from zero was measured. The magnitude of the photocurrent indicates the magnitude of the number of active electrons obtained from photon irradiation. The bias voltage is added to make it easier to extract the photoexcited active electrons to the outside.The purpose is to make it easier to observe the potential performance inherent to each photocatalyst, and to apply the bias itself to improve the photocatalytic performance. is there.
【００３１】図３に結果を示す。まずα−Ｆｅ2Ｏ3では
電位がゼロよりプラス側へ０.５Ｖ位上げた時に初めて
光電流が得られる状況にある。また１Ｖを越える電位領
域に於いても光電流は２ｍＡ／ｃｍ2程度である。次に
アナターゼ型酸化チタンは無バイアスで光電流が得ら
れ、電位が上がるに従って上昇し、１.５Ｖに於いて９
ｍＡ／ｃｍ2の光電流を得た。最後に酸化チタンとアル
ファ型酸化第二鉄とを組合せたサンプルでは、まず無バ
イアス近傍で僅かではあるが酸化チタン単独に比べて光
電流が高くなっている。次に電位がゼロから１Ｖの領域
では酸化チタンとアルファ型酸化第二鉄の単独の光電流
を合わせたものと比較して光電流が高いことがわかる。
更に、電位が１Ｖから１.５Ｖの領域では光電流が大き
く上昇して３２ｍＡ／ｃｍ2に達している。単純な和で
は１１ｍＡ／ｃｍ2であるから、約３倍になっている。
これらのことは、アナターゼ型酸化チタンの光触媒性能
とアルファ型酸化第二鉄の光触媒性能との相乗効果によ
るものと考えられる。アルファ型酸化第二鉄は５４０ｎ
ｍ以下の可視光によって光励起するのでこれとの組合せ
では紫外光のみならず可視光も有効利用でき、太陽光や
広い波長領域の光源でも相乗効果を発揮出来ることにな
る。光電流の増大は水分解水素生成や抗菌、脱臭、防汚
効果の向上をもたらす。図２に於いて、上記の例は光触
媒Ｉがアナターゼ型酸化チタンで光触媒IIがアルファ型
酸化第二鉄であったが、それが逆になっても相乗効果は
得られる。上記にも触れたが、発生する活性電子やホー
ルは光触媒膜の中を自由に移動できる。また光触媒膜の
製法が電子移動型の膜を形成している。FIG. 3 shows the results. First, in the case of α-Fe 2 O 3 , a photocurrent is obtained only when the potential is increased from the zero to the plus side by about 0.5 V. The photocurrent is about 2 mA / cm 2 even in a potential region exceeding 1 V. Next, a photocurrent is obtained with no bias from the anatase type titanium oxide, and increases as the potential rises.
A photocurrent of mA / cm 2 was obtained. Finally, in the sample in which titanium oxide and alpha-type ferric oxide are combined, the photocurrent is slightly higher in the vicinity of no bias than in the case of titanium oxide alone. Next, in the region where the potential is zero to 1 V, the photocurrent is higher than that obtained by combining the photocurrents of titanium oxide and alpha ferric oxide alone.
Further, in the region where the potential is from 1 V to 1.5 V, the photocurrent greatly increases and reaches 32 mA / cm 2 . The simple sum is 11 mA / cm 2, which is about three times.
This is considered to be due to a synergistic effect between the photocatalytic performance of anatase type titanium oxide and the photocatalytic performance of alpha type ferric oxide. Alpha type ferric oxide is 540n
Since light is excited by visible light of m or less, in combination with this, not only ultraviolet light but also visible light can be effectively used, and a synergistic effect can be exerted even with sunlight or a light source in a wide wavelength range. The increase in photocurrent results in the generation of hydrocracked hydrogen and the improvement of antibacterial, deodorizing, and antifouling effects. In FIG. 2, in the above example, the photocatalyst I was anatase-type titanium oxide and the photocatalyst II was alpha-type ferric oxide, but a synergistic effect can be obtained even if the reverse is true. As mentioned above, the generated active electrons and holes can move freely in the photocatalytic film. In addition, the method for producing the photocatalytic film forms an electron transfer type film.
【００３２】[0032]
【発明の効果】本発明によれば異なる種類の光触媒の組
合せが相乗効果を発揮して各々単独の和以上の光触媒性
能を示す。According to the present invention, combinations of different types of photocatalysts exhibit a synergistic effect and exhibit photocatalytic performance that is greater than or equal to the sum of the individual types.
【図１】光触媒ＩとIIとの相乗効果の原理図。FIG. 1 is a principle diagram of a synergistic effect between photocatalysts I and II.
【図２】光触媒の構造例を示す図。FIG. 2 is a diagram showing a structural example of a photocatalyst.
【図３】相乗効果を示す図。FIG. 3 shows a synergistic effect.
１…ガラス、２…光触媒Ｉ、３…光触媒II。 1 ... glass, 2 ... photocatalyst I, 3 ... photocatalyst II.
フロントページの続き Ｆターム(参考） 4C080 AA07 AA10 BB02 BB05 CC01 JJ06 MM02 QQ03 4G069 AA02 AA11 BA04A BA04B BB04A BB04B BC66A BC66B CA10 EC22X EC22Y EE09Continued on the front page F term (reference) 4C080 AA07 AA10 BB02 BB05 CC01 JJ06 MM02 QQ03 4G069 AA02 AA11 BA04A BA04B BB04A BB04B BC66A BC66B CA10 EC22X EC22Y EE09
Claims (6)
た構造で光触媒効果が各々単独の和以上になる相乗効果
型光触媒。1. A synergistic effect photocatalyst having a structure in which different types of photocatalysts are combined in a layered form, and each of which has a photocatalytic effect equal to or more than a single sum.
で外部より電圧を付加することにより光触媒同士の相乗
効果を高めた相乗効果型光触媒。2. A synergistic effect type photocatalyst having a structure in which different types of photocatalysts are combined and in which a synergistic effect between the photocatalysts is enhanced by applying an external voltage.
発揮する光触媒と可視光でも励起活性化して光触媒効果
を発揮する光触媒とを組み合わせて各々単独の場合の和
よりも光触媒効果が向上できる相乗効果型光触媒。3. A combination of a photocatalyst which is excited and activated by ultraviolet light to exhibit a photocatalytic effect and a photocatalyst which is excited and activated even by visible light to exhibit a photocatalytic effect can improve the photocatalytic effect more than the sum of the individual cases. Synergistic photocatalyst.
ｅ−ＴｉＯ２）の光触媒とアルファ型酸化第二鉄（α−
Ｆｅ２Ｏ３）の光触媒とを組み合わせた構造で光触媒効
果が各々単独の和以上になる相乗効果型光触媒。4. Anatase type titanium oxide (anatas)
e-TiO2) photocatalyst and alpha-type ferric oxide (α-
A synergistic effect type photocatalyst having a structure in which a photocatalyst of Fe2O3) is combined and having a photocatalytic effect each of which is equal to or more than a single sum.
ｅ−ＴｉＯ２）の光触媒とアルファ型酸化第二鉄（α−
Ｆｅ２Ｏ３）の光触媒とを組み合わせた構造で外部より
電圧を付加することにより光触媒同士の相乗効果を高め
た相乗効果型光触媒。5. Anatase type titanium oxide (anatas)
e-TiO2) photocatalyst and alpha-type ferric oxide (α-
A synergistic effect type photocatalyst in which a photocatalyst of Fe2O3) is combined and a synergistic effect between the photocatalysts is enhanced by applying an external voltage.
おいて、上記組み合わせは、層状に組み合わせたことを
特徴とする相乗効果型光触媒。6. The synergistic effect type photocatalyst according to claim 2, wherein the combination is a layered combination.
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| Country | Link |
|---|---|
| JP (1) | JP2002159863A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1348675A1 (en) * | 2002-03-27 | 2003-10-01 | Murakami Corporation | Substrate coated with a laminated photocatalytic film |
| JP2008104899A (en) * | 2006-10-23 | 2008-05-08 | Sharp Corp | Photocatalyst membrane, manufacturing method of photocatalyst membrane, and hydrogen-generating device using the catalyst |
| JP2009050827A (en) * | 2007-08-29 | 2009-03-12 | Sharp Corp | Semiconductor oxide film, its manufacturing method and hydrogen generation apparatus using semiconductor oxide film |
-
2000
- 2000-11-24 JP JP2000362682A patent/JP2002159863A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1348675A1 (en) * | 2002-03-27 | 2003-10-01 | Murakami Corporation | Substrate coated with a laminated photocatalytic film |
| JP2008104899A (en) * | 2006-10-23 | 2008-05-08 | Sharp Corp | Photocatalyst membrane, manufacturing method of photocatalyst membrane, and hydrogen-generating device using the catalyst |
| JP2009050827A (en) * | 2007-08-29 | 2009-03-12 | Sharp Corp | Semiconductor oxide film, its manufacturing method and hydrogen generation apparatus using semiconductor oxide film |
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