JP2005342601A - Visible light-responsive photocatalyst and manufacturing method therefor - Google Patents
Visible light-responsive photocatalyst and manufacturing method therefor Download PDFInfo
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- JP2005342601A JP2005342601A JP2004164396A JP2004164396A JP2005342601A JP 2005342601 A JP2005342601 A JP 2005342601A JP 2004164396 A JP2004164396 A JP 2004164396A JP 2004164396 A JP2004164396 A JP 2004164396A JP 2005342601 A JP2005342601 A JP 2005342601A
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Abstract
Description
本発明は、光触媒であるTiO2を可視光感応型として用いることを可能にした可視光感応型光触媒とその調製方法に関する。 The present invention relates to a visible light sensitive photocatalyst capable of using TiO 2 as a photocatalyst as a visible light sensitive type and a method for preparing the same.
近年、半導体光触媒による酸化還元反応を利用した商品開発が盛んに行われている。例えば、塗布された光触媒により自浄作用を有するトンネル照明、添加された光触媒により抗菌作用を有するタイル、エアフィルタに担持された光触媒により空気中の有害物を分解する空気清浄機などが挙げられる。これらの商品に用いられている半導体光触媒のほとんどは、酸化チタンである。 In recent years, product development utilizing an oxidation-reduction reaction by a semiconductor photocatalyst has been actively performed. For example, tunnel lighting having a self-cleaning action by an applied photocatalyst, tile having an antibacterial action by an added photocatalyst, an air cleaner that decomposes harmful substances in the air by a photocatalyst carried on an air filter, and the like. Most of the semiconductor photocatalysts used in these products are titanium oxide.
酸化チタンは、化学的に安定で安価かつ人体に対して安全であるため広く採用されているが、励起するために、アナタース型で３８０ｎｍ以下、ルチル型で４００ｎｍ以下の紫外光を必要とする。 Titanium oxide is widely used because it is chemically stable, inexpensive, and safe for the human body, but in order to excite, it requires ultraviolet light of 380 nm or less for the anatase type and 400 nm or less for the rutile type.
しかし，太陽光を構成する要素の主たる部分は波長400 〜 800 nmの可視光であり，これらの光触媒が機能する波長380 nm以下の紫外線はわずか3 % 前後である。また，蛍光灯の光も波長400 〜 500 nmの可視光が主である。したがって，これらの可視光を有効に活用するためには、可視領域の光で作用する光触媒の開発が必要である。 However, the main component of sunlight is visible light with a wavelength of 400 to 800 nm, and only about 3% of UV light with a wavelength of 380 nm or less is used for these photocatalysts. Also, fluorescent light is mainly visible light with a wavelength of 400-500 nm. Therefore, in order to effectively use these visible lights, it is necessary to develop a photocatalyst that works with visible light.
従来、光触媒であるTiO2を可視光感応型に改質させ、環境清浄化が可能となる光触媒の開発が多くの研究者によって試みられてきた。可視光応答化の方法としては、１）酸化チタンに不純物準位を形成させ、励起に必要なバンドギャップエネルギーを減少させる方法、２）色素を酸化チタン表面へ吸着させ、色素の励起によって生じた電子と正孔を用いる方法があり、例えば，酸化チタン格子中に遷移金属イオンをイオン注入して酸化チタンの吸収端を長波長側へシフトするイオン注入法や、Ｎ2／Ａrプラズマ雰囲気中での酸化チタンスパッタリング、アンモニア含有雰囲気下での酸化チタンの熱処理による窒素ドープは、上記１）に分類されるものである（非特許文献１〜３等参照）。 In the past, many researchers have attempted to develop photocatalysts that can be made environmentally clean by modifying the photocatalyst TiO 2 into a visible light sensitive type. Visible light response methods include: 1) a method of forming impurity levels in titanium oxide and reducing the bandgap energy required for excitation; 2) adsorption of the dye onto the titanium oxide surface; There are methods using electrons and holes. For example, an ion implantation method in which transition metal ions are ion-implanted into a titanium oxide lattice to shift the absorption edge of titanium oxide to a longer wavelength side, or in an N 2 / Ar plasma atmosphere Nitrogen doping by titanium oxide sputtering and heat treatment of titanium oxide in an ammonia-containing atmosphere is classified as 1) above (see Non-Patent Documents 1 to 3, etc.).
しかしながら、上述した多くの方法は、いずれも製法上の制約があり、コストがかかったり、また、長期安定性に乏しい等、光活性能などの点で十分な評価が得られておらず、いまだ実用化されていない。 However, many of the above-mentioned methods are limited in terms of manufacturing method, cost is high, and long-term stability is poor. Not put into practical use.
本発明は、上述した事情に鑑みてなされたものであり、多量に存在し、しかも安全な可視光線を利用してTiO2を誘起することを可能にした可視光感応型光触媒とその調製方法を提供することを主たる課題としている。 The present invention has been made in view of the above-described circumstances, and a visible light-sensitive photocatalyst that can be induced in a large amount and that can induce TiO 2 using safe visible light and a method for preparing the same. The main challenge is to provide it.
本発明者らは、可視光によるTiO2 活性化のためにコロイド状のAu が発光するプラズモンを用いることを提案しており、一例として，LB膜を用いてTiO2微粒子を一粒子膜状にし，さらにAu コロイドを付着させる研究を行っている。
一方，逆ミセル法で調製された酸化チタン微粒子は、焼成することなしに紫外光で光触媒能（触媒活性）を示すことを見出している。
The present inventors have proposed the use of plasmon that emits colloidal Au for the activation of TiO 2 by visible light. As an example, the LB film is used to make TiO 2 fine particles into a one-particle film. In addition, we are conducting research to attach Au colloid.
On the other hand, the titanium oxide fine particles prepared by the reverse micelle method have been found to exhibit photocatalytic activity (catalytic activity) with ultraviolet light without firing.
本発明は、これらの知見に基づき、完成されたものであり、逆ミセル法によってAu 微粒子を内包したTiO2 の複合微粒子を調製し，Auのプラズモンによって光触媒としてのTiO2のバンドギャップ領域を変移させ，可視光領域でも光触媒活性機能を示すことが可能な可視光感応型の光触媒を得ようとするものである。 The present invention has been completed based on these findings, and prepared composite fine particles of TiO 2 containing Au fine particles by the reverse micelle method, and changed the band gap region of TiO 2 as a photocatalyst by Au plasmons. Thus, a visible light sensitive photocatalyst capable of exhibiting a photocatalytic activity function even in the visible light region is to be obtained.
即ち、前記課題を達成するために、この発明に係る可視光感応型光触媒は、金微粒子を酸化チタン層で包摂した複合微粒子を形成成分とすることを特徴としている（請求項１）。ここで、金微粒子を酸化チタン層で包摂するとは、完全に覆っている状態、若しくは、完全に覆っていなくても、少なくとも覆っている状態が存在することを意味し、AuとTiO2とが単に隣同士に共存しているような状態を除く意味である。 That is, in order to achieve the above object, the visible light sensitive photocatalyst according to the present invention is characterized in that composite fine particles in which gold fine particles are included in a titanium oxide layer are used as a forming component (claim 1). Here, subsumes with gold particles of titanium oxide layer, completely the overlying condition, or, even if not completely covered, means that the state in which at least covers the presence and Au and TiO 2 It simply means excluding the situation where the neighbors coexist.
このような構成とすることで、Ａｕ微粒子に可視光が照射されることにより生じるプラズモン電子で酸化チタンを活性化させることができ、可視光で作用する光触媒を創製することが可能となる。 With such a configuration, titanium oxide can be activated by plasmon electrons generated by irradiating Au fine particles with visible light, and a photocatalyst that works with visible light can be created.
このような金微粒子を包摂したチタニア微粒子を調製するには、非水系の制限反応場で、金イオンを還元して金コロイドを形成し、前記金コロイドの粒子面で有機チタン錯体を加水分解と縮合反応させて前記金コロイドを酸化チタン層で包摂するとよい（請求項２）。ここで、非水系の制限反応場は、炭素数５〜１６の炭化水素油、好ましくは炭素数６〜７の環状又は直鎖の炭化水素油からなる溶媒中において、ＨＬＢが１０〜１６の非イオン性界面活性物質、好ましくは、下記の一般式（化１）で示すPolyoxyethylene monoalkyl-ether [ 以下Cm(EO)nと略す]のうち、m が10から16、n が4から6の界面活性剤が形成する逆ミセルまたは逆マイクロエマルション中を利用するとよい（請求項３）。 In order to prepare titania fine particles including such gold fine particles, a gold colloid is formed by reducing gold ions in a non-aqueous limited reaction field, and an organic titanium complex is hydrolyzed on the particle surface of the gold colloid. The gold colloid may be included in the titanium oxide layer by a condensation reaction (claim 2). Here, the non-aqueous limited reaction field is a non-aqueous solvent having a carbon number of 5 to 16, preferably a cyclic or linear hydrocarbon oil having a carbon number of 6 to 7, and an HLB of 10 to 16. An ionic surfactant, preferably a polyoxyethylene monoalkyl-ether [hereinafter abbreviated as C m (EO) n ] represented by the following general formula (Formula 1), where m is 10 to 16 and n is 4 to 6 It is recommended to use reverse micelles or reverse microemulsions formed by the active agent (claim 3).
例えば、シクロヘキサン溶媒中でペンタオキシエチレンドデシルエーテルが形成する非イオン界面活性剤の逆ミセルまたは逆マイクロエマルション中を利用するとよい。
また、有機チタン錯体は、チタン金属アルコキシドならいずれも使用可能である。
For example, it may be used in a reverse micelle or reverse microemulsion of a nonionic surfactant formed by pentaoxyethylene dodecyl ether in a cyclohexane solvent.
Any organic titanium complex can be used as long as it is a titanium metal alkoxide.
より具体的な調製法としては、ＨＬＢが１０〜１６の非イオン性界面活性剤を炭素数５〜１６の炭化水素油からなる溶媒中に溶解させ、この溶液に水溶性の金塩を可溶化させる工程と、この可溶化させた金イオンに対し、還元剤を所定の比で添加し、攪拌することで逆ミセル中に金微粒子を調製する工程と、前記金微粒子を含有した逆ミセルの外相の炭化水素油に所定量の有機チタン錯体を添加して加水分解と縮合反応させることで前記金コロイドを酸化チタン層で包摂する工程とを含むとよい（請求項４）。
ここで、水溶性の金塩は、溶解後に金イオンを形成する、例えば、塩化金（III）酸・四水和物などを用いればよく、上述の調製法は、例えば、非イオン性界面活性剤をシクロヘキサンに溶解させ、この溶液に塩化金（III）酸水溶液を可溶化させる工程と、この可溶化させた金イオンに対し、還元剤を所定の比で添加し、攪拌することで逆ミセル中に金微粒子を調製する工程と、金微粒子を含有した逆ミセルの外相のシクロヘキサンに所定量の有機チタン錯体を添加して加水分解と縮合反応させることで前記金コロイドを酸化チタン層で包摂する工程とを含むように構成してもよい。
As a more specific preparation method, a nonionic surfactant having an HLB of 10 to 16 is dissolved in a solvent composed of a hydrocarbon oil having 5 to 16 carbon atoms, and a water-soluble gold salt is solubilized in this solution. A step of adding a reducing agent to the solubilized gold ions at a predetermined ratio and stirring to prepare gold fine particles in reverse micelles, and an outer phase of the reverse micelles containing the gold fine particles. And adding a predetermined amount of an organotitanium complex to the hydrocarbon oil to cause hydrolysis and condensation reaction to include the gold colloid in a titanium oxide layer (Claim 4).
Here, as the water-soluble gold salt, gold ions are formed after dissolution. For example, gold chloride (III) acid tetrahydrate or the like may be used. Dissolving the agent in cyclohexane, solubilizing the aqueous solution of gold chloride (III) acid in this solution, and adding the reducing agent to the solubilized gold ion at a predetermined ratio and stirring, reverse micelle The gold colloid is included in the titanium oxide layer by adding a predetermined amount of organotitanium complex to cyclohexane, which is the outer phase of the reverse micelle containing gold fine particles, and hydrolyzing and condensing it. You may comprise so that a process may be included.
さらに、前記金コロイドと前記有機チタン錯体とをモル比が１：１〜１：１５０となるように前記有機チタン錯体を添加することが好ましく（請求項５）、金コロイドと酸化チタン層との間の挟雑物を除去して可視光の感応性を高めるために、前記金コロイドを酸化チタン層で包摂した粒子を取り出し、前記非イオン性界面活性剤の分解温度よりも高く、酸化チタンのアナタース変換温度よりも低い温度で加熱処理する工程をさらに含むとよい（請求項６）。 Furthermore, it is preferable to add the organotitanium complex so that the molar ratio of the colloidal gold and the organotitanium complex is 1: 1 to 1: 150 (Claim 5). In order to remove the interstitial material between them and increase the sensitivity of visible light, the particles containing the gold colloid in the titanium oxide layer are taken out, and the decomposition temperature of the nonionic surfactant is higher than that of the titanium oxide. It is good to further include the process of heat-processing at temperature lower than an anatase conversion temperature (Claim 6).
また、このような金微粒子を包摂したチタニア微粒子を調製するには、あらかじめ調製された金微粒子分散溶液を逆ミセル中へ可溶化させ、その後、前記金微粒子を含有した逆ミセル界面で前記有機チタン錯体を加水分解と縮合反応させることで前記金微粒子を酸化チタン層で包摂するようにしてもよい（請求項７）。ここで、有機チタン錯体は、チタン金属アルコキシドならいずれも使用可能である。 Further, in order to prepare titania fine particles including such gold fine particles, a gold fine particle dispersion prepared in advance is solubilized in reverse micelles, and then the organic titanium at the reverse micelle interface containing the gold fine particles. The gold fine particles may be included in the titanium oxide layer by subjecting the complex to hydrolysis and condensation reaction (claim 7). Here, as the organic titanium complex, any titanium metal alkoxide can be used.
より具体的な調製法としては、あらかじめ金微粒子分散溶液を調製する工程と、非イオン性界面活性剤を炭素数５〜１６の炭化水素油からなる溶液中に溶解させ、この溶液に前記金微粒子分散溶液を可溶化させる工程と、前記金微粒子を含有した逆ミセルの外相の炭化水素油に所定量の有機チタン錯体を添加して加水分解と縮合反応させることで前記金微粒子を酸化チタン層で包摂する工程とを含むとよい（請求項８）。 As a more specific preparation method, a step of preparing a gold fine particle dispersion solution in advance, a nonionic surfactant is dissolved in a solution composed of a hydrocarbon oil having 5 to 16 carbon atoms, and the gold fine particles are dissolved in this solution. A step of solubilizing the dispersion solution, and adding a predetermined amount of an organic titanium complex to the hydrocarbon oil of the outer phase of the reverse micelle containing the gold fine particles to cause hydrolysis and condensation reaction, thereby allowing the gold fine particles to form a titanium oxide layer. Including the step of including (Claim 8).
例えば、上述の調製法を、あらかじめ金微粒子分散溶液を調整する工程と、非イオン性界面活性剤をシクロヘキサンに溶解させ、この溶液に前記金微粒子分散溶液を可溶化させる工程と、前記金微粒子を含有した逆ミセルの外相のシクロヘキサンに所定量の有機チタニア錯体を添加して加水分解させることで前記金微粒子を酸化チタン層で包摂する工程とを含むように構成してもよい。 For example, the above-described preparation method includes a step of preparing a gold fine particle dispersion in advance, a step of dissolving a nonionic surfactant in cyclohexane, and solubilizing the gold fine particle dispersion in this solution; A step of adding a predetermined amount of an organic titania complex to cyclohexane as an outer phase of the reverse micelle contained therein and hydrolyzing it to include the gold fine particles with a titanium oxide layer may be included.
このような製法においても、可視光での感応性を高めるために、前記金微粒子を酸化チタン層で包摂した粒子を取り出し、前記非イオン性界面活性剤の分解温度よりも高く、酸化チタンのアナタース変換温度よりも低い温度で加熱処理する工程をさらに含むとよい（請求項９）。 Even in such a production method, in order to enhance the sensitivity to visible light, the particles in which the gold fine particles are included in the titanium oxide layer are taken out, and the decomposition temperature of the nonionic surfactant is higher. It is good to further include the process of heat-processing at temperature lower than conversion temperature (Claim 9).
以上述べたように、この発明に係る可視光感応型光触媒によれば、金微粒子を酸化チタン層で包摂した複合微粒子を形成成分としているので、金微粒子に可視光を照射させることにより生じるブラズモン電子を酸化チタンの活性化のために利用することができ、可視光領域でTiO2を誘起する機能を有する光触媒を提供することが可能となる。また、金のプラズモン現象は、光照射によって劣化が起こらないので、実用化において適切な材料を提供することが可能となる。 As described above, according to the visible light sensitive photocatalyst according to the present invention, since the composite fine particles including the gold fine particles in the titanium oxide layer are used as the forming component, the plasmon electrons generated by irradiating the gold fine particles with visible light are used. Can be used for activation of titanium oxide, and a photocatalyst having a function of inducing TiO 2 in the visible light region can be provided. In addition, since the gold plasmon phenomenon does not deteriorate due to light irradiation, it is possible to provide an appropriate material for practical use.
また、このような金微粒子を酸化チタン層で包摂した複合微粒子を調製するにあたり、非水系の制限反応場で、金イオンを還元して金コロイドを形成し、前記金コロイドの粒子面で有機チタン錯体を加水分解と縮合反応させて金コロイドを酸化チタン層で包摂する方法と、あらかじめ調製された金微粒子分散溶液を逆ミセル中へ可溶化させ、その後、前記金微粒子を含有した逆ミセル界面で前記有機チタン錯体を加水分解と縮合反応させることで金微粒子を酸化チタン層で包摂する方法とを採用することで、金微粒子を包摂した酸化チタンの複合微粒子を効率良く調製することが可能となる。 Further, in preparing composite fine particles including such gold fine particles in a titanium oxide layer, gold ions are reduced to form gold colloids in a non-aqueous limited reaction field, and organic titanium is formed on the surface of the gold colloid particles. A method in which a complex is hydrolyzed and condensed to include a gold colloid in a titanium oxide layer, and a gold fine particle dispersion prepared in advance is solubilized in a reverse micelle, and then at the reverse micelle interface containing the gold fine particle. By adopting a method in which the organic titanium complex is hydrolyzed and condensed to include gold fine particles in a titanium oxide layer, it becomes possible to efficiently prepare titanium oxide composite fine particles including gold fine particles. .
以下、この発明の最良の実施形態を図面を参照しながら説明する。 DESCRIPTION OF THE PREFERRED EMBODIMENTS The best embodiment of the present invention will be described below with reference to the drawings.
図１に金微粒子を酸化チタン層で包摂したＡｕ／ＴｉＯ2 複合微粒子の概念図が示されている。このような複合微粒子にあっては、金微粒子が可視光照射によりプラズモン現象を起こし、このプラズモン電子により、ＴｉＯ2が光触媒活性を示すことが期待される。そこで、このようなＡｕ／ＴｉＯ2 複合微粒子を製造するにあたり、本発明者らは次の２つの製造方法（ルート１、ルート２）を完成させるに至った。 FIG. 1 shows a conceptual diagram of Au / TiO 2 composite fine particles in which gold fine particles are included in a titanium oxide layer. In such composite fine particles, the gold fine particles cause a plasmon phenomenon by irradiation with visible light, and it is expected that TiO 2 exhibits photocatalytic activity due to the plasmon electrons. Therefore, in producing such Au / TiO 2 composite fine particles, the present inventors have completed the following two production methods (Route 1 and Route 2).
［ルート１］ 非水系の制限反応場である逆ミセル中でＡｕ微粒子を調製し、それを用いてＡｕ／ＴｉＯ2 複合微粒子を調製する方法。即ち、Ａｕ微粒子の原料である塩化金（III）酸水溶液を逆ミセル中に可溶化して還元することで、金コロイドを形成し（Ａｕ微粒子含有逆ミセル溶液を生成し）、しかる後にこの非水溶液に有機チタン錯体を添加し、逆ミセル界面で有機チタン錯体を加水分解と縮合反応させて金コロイドをＴｉＯ2 で包摂したＡｕ／ＴｉＯ2 複合微粒子を生成する方法。 [Route 1] Au fine particles are prepared in reverse micelles which are non-aqueous limited reaction fields, and Au / TiO 2 is used by using them. A method of preparing composite microparticles. That is, the gold chloride (III) acid aqueous solution that is the raw material for the Au fine particles is solubilized and reduced in reverse micelles to form a gold colloid (produce a reverse micelle solution containing Au fine particles). An organic titanium complex is added to the aqueous solution, and the organic titanium complex is hydrolyzed and condensed at the reverse micelle interface to convert the gold colloid into TiO 2. Au / TiO 2 included in A method of producing composite particulates.
［ルート２］ 予め水溶液中で調製したＡｕ微粒子を原料に用いる方法。即ち、予め調製されたＡｕ微粒子分散溶液を逆ミセル中へ可溶化させ、続いてＡｕ微粒子含有逆ミセル溶液へ有機チタン錯体を添加し、逆ミセル界面で有機チタン錯体を加水分解と縮合反応させることにより金コロイドをＴｉＯ2 で包摂したＡｕ／ＴｉＯ2 複合微粒子を生成する方法。 [Route 2] A method in which Au fine particles prepared in advance in an aqueous solution are used as raw materials. That is, the Au fine particle dispersion prepared in advance is solubilized in reverse micelles, and then an organic titanium complex is added to the reverse fine micelle solution containing Au fine particles, and the organic titanium complex is subjected to hydrolysis and condensation reaction at the reverse micelle interface. By colloidal gold TiO 2 Au / TiO 2 included in A method of producing composite particulates.
１［試薬］
Ａｕ／ＴｉＯ2 複合微粒子を製造する以上の方法を実現するために、次の試薬を用いた。
○ 逆ミセルを形成するのに使用した界面活性剤は非イオン性界面活性剤 Polyoxyethylene monoalkyl-ether ( NIKKOL ) [ 以下Cm(EO)nと略す ] を精製せずにそのまま用いた。Cm(EO)nの構造を化２に示す。
1 [reagent]
In order to realize the above method for producing Au / TiO2 composite fine particles, the following reagents were used.
○ The surfactant used to form reverse micelles was the nonionic surfactant Polyoxyethylene monoalkyl-ether (NIKKOL) [hereinafter abbreviated as C m (EO) n ] used without purification. The structure of C m (EO) n is shown in Chemical Formula 2.
○ 溶媒には、Cyclohexane ( 和光純薬 )を精製せずにそのまま用いた。
○ 逆ミセル中に可溶化させる試薬は， Au 微粒子の原料である塩化金（III）酸・四水和物 : HAuCl4 ・4H2O ( 和光純薬 ) を用い，所定の濃度に調製した。
○ 還元剤には、Trisodium Citrate Dihydrate:Na3C6H5O７・2H2O（クエン酸ナトリウム二水和物、和光純薬）、又は、Sodium Tetrahydroborate : NaBH4 ( Wako ) を用いた。
○ TiO2 の原料は，Tetraethoxy-o-titanate ( MERCK ) [ 以下TEOTと略す ] を用いた。TEOT の構造を化３に示す。
○ As a solvent, cyclohexane (Wako Pure Chemical Industries) was used as it was without purification.
○ Reagents to be solubilized in reverse micelles were prepared to a predetermined concentration using gold chloride (III) acid tetrahydrate: HAuCl 4 · 4H 2 O (Wako Pure Chemical Industries), which is the raw material for Au fine particles.
O Trisodium Citrate Dihydrate: Na 3 C 6 H 5 O 7 · 2H 2 O (sodium citrate dihydrate, Wako Pure Chemicals) or Sodium Tetrahydroborate: NaBH 4 (Wako) was used as the reducing agent.
○ material of TiO 2 was used Tetraethoxy-o-titanate (MERCK) [ hereinafter referred to as TEOT]. The structure of TEOT is shown in Chemical formula 3.
○ 光触媒反応を調べるために，水溶性色素であるRhodamine B (関東化学)［以下、ＲｈＢと略す］及びMethyl Orange ( 和光純薬) [ 以下MOと略す ] を用いた。ＲｈＢとMO の構造を化学４、化学５に示す。 In order to investigate the photocatalytic reaction, water-soluble dyes Rhodamine B (Kanto Chemical) [hereinafter abbreviated as RhB] and Methyl Orange (Wako Pure Chemical Industries) [hereinafter abbreviated as MO] were used. The structures of RhB and MO are shown in Chemistry 4 and Chemistry 5.
○ 光照射による分解実験を比較するために、市販されているアナタース型酸化チタンであるＳＴ−０１を用いた。 In order to compare the decomposition experiment by light irradiation, ST-01 which is a commercially available anatase type titanium oxide was used.
２ [測定装置]
複合微粒子を製造するために、以下の装置を利用した。
○バス型超音波照射装置 ( 100mW, TRANSSONIC T570, Elma )
○紫外可視分光光度計 : UV-vis ( V-570, Jasco )
○電気泳動光散乱光度計( ELS-8000, OTSUKA ELECTRONICS )
○透過型電子顕微鏡 : TEM ( JEM-2000EX/FXII, 日本電子 )
○遠心分離器 テーブルトップ高速冷却遠心機 (クボタ)
遠心機（H-108NA，コクサン）
○光照射装置，光源 超高圧水銀ランプ(500W, Optical Module,ウシオ電機 )
高圧水銀ランプ（100W,UM-102,ウシオ電機）
○紫外線遮蔽用フィルター
(V-Y47，50×50mm，厚さ3mm，東京芝浦株式会社)
2 [Measurement equipment]
In order to produce composite fine particles, the following apparatus was used.
○ Bath type ultrasonic irradiation equipment (100mW, TRANSSONIC T570, Elma)
○ UV-Vis spectrophotometer: UV-vis (V-570, Jasco)
○ Electrophoretic light scattering photometer (ELS-8000, OTSUKA ELECTRONICS)
○ Transmission electron microscope: TEM (JEM-2000EX / FXII, JEOL)
○ Centrifuge Table top high-speed cooling centrifuge (KUBOTA)
Centrifuge (H-108NA, Kokusan)
○ Light irradiation device, light source Ultra-high pressure mercury lamp (500W, Optical Module, USHIO)
High pressure mercury lamp (100W, UM-102, USHIO)
○ Ultraviolet shielding filter
(V-Y47, 50 × 50mm, thickness 3mm, Tokyo Shibaura Corporation)
３ ルート１について
３−１ Au/TiO2 複合微粒子の調製手順
図２に示されるように、このルートで提案される調製方法は、Ａｕ微粒子の原料である塩化金（III）酸水溶液を逆ミセル中に可溶化するステップと、この可溶化された逆ミセルを還元して金コロイドを形成（Ａｕ微粒子含有逆ミセル溶液を生成）するステップと、この非水溶液に有機チタン錯体を溶解させて、逆ミセル界面で加水分解と縮合反応させることでＴｉＯ2 を形成し、金コロイドをＴｉＯ2 で包摂したＡｕ／ＴｉＯ2 複合微粒子を生成するステップとを有している。
3 About Route 1 3-1 Preparation Procedure of Au / TiO 2 Composite Fine Particles As shown in FIG. 2, the preparation method proposed in this route is based on reverse micelle using an aqueous solution of gold chloride (III) acid as a raw material for Au fine particles. A step of solubilizing in the inside, a step of reducing the solubilized reverse micelle to form a gold colloid (producing a reverse micelle solution containing Au fine particles), and a step of dissolving the organic titanium complex in the non-aqueous solution to reverse the TiO 2 was formed by causing hydrolysis and condensation reactions in micelles surfactants, colloidal gold and a step of generating a Au / TiO 2 composite fine particles inclusion in TiO 2.
３−２ 試薬の調製
３−２−１ 塩化金（III）酸水溶液の調製
Au 微粒子の原料である塩化金 (III) 酸・四水和物を正確に秤量し，Millipore超純水装置で精製して得た純水に溶解した。濃度 ２０mmol/dm3 〜 ４０mmol/dm3 とした。
３−２−２ 逆ミセル溶液の調製
界面活性剤 C12(EO)5 を Cyclohexane に溶解させ，0.1 mol/dm3 のC12(EO)5/ Cyclohexane 溶液を調製した。この際，均一溶解を早めるためにバス型超音波照射装置 ( 100mW, TRANSSONIC T570, Elma ) を用いて，超音波を照射した。本研究では，界面活性剤濃度は cmc 以上の 0.1 mol/ dm3 で一定とした。次に，このC12(EO)5/cyclohexane 溶液に ３−２−１で調製した塩化金(III)酸水溶液を可溶化した。このとき，界面活性剤に対する水のモル比 (Ｒw = H2O/ C12(EO)5 ) をＲw = 5 で一定とし，可溶化時間を２時間とした。尚、Ｒwは、５〜２０とすることが好ましい。Ｒw = ２０よりも大きくすると、逆ミセルが保てなくなるからである。
３−２−３ 逆ミセル法によるＡｕ微粒子の調製
３−２−２で調製された、逆ミセル溶液へ可溶化されたＡu3+ に対して、還元剤ＮａＢＨ4をＡu3+とＮａＢＨ4のモル比を１／５となるように溶液中に直接加えた後、２０℃で２時間攪拌することにより、逆ミセル内でＡｕ微粒子を調製した。
３−２−４ 逆ミセル法によるAu/TiO 2 複合微粒子の調製
３−２−３で調製された Au 微粒子を含有した逆ミセル溶液の外相である Cyclohexane に所定量の TEOT を撹拌しながら添加し，逆ミセル界面で TEOT を加水分解と縮合反応させることにより Au/TiO2複合微粒子を調製した。このとき， Au と加水分解してできる TiO2 の物質量比 ( Au : TiO2 ) を変化させて調製した。還元時間を２時間，加水分解反応時間を24時間，反応温度を20±1℃ とした。
３−２−５ 調製された複合微粒子の精製
調製されたAu/TiO2 複合微粒子を遠心分離機：テーブルトップ高速冷却遠心器（クボタ、15000rpm×20min）もしくは遠心器（Ｈ−１０８ＮＡ，コクサン、3500rpm×30min）を用いて遠心分離した。上澄みを除去し、沈殿物へMethanolを加えてさらに遠心分離を行なう洗浄工程を５〜６度繰り返した。洗浄した複合微粒子を減圧下100℃×５時間乾燥し、紫色の粉末を得た。
3-2 Preparation of reagents
3-2-1 Preparation of aqueous solution of gold chloride (III) acid
The gold chloride (III) acid tetrahydrate, which is the raw material for Au fine particles, was accurately weighed and dissolved in pure water obtained by purification with a Millipore ultrapure water device. The concentration was 20 mmol / dm 3 to 40 mmol / dm 3 .
3-2-2 Preparation of reverse micelle solution Surfactant C 12 (EO) 5 was dissolved in cyclohexane to prepare a 0.1 mol / dm 3 C 12 (EO) 5 / cyclohexane solution. At this time, in order to accelerate uniform dissolution, ultrasonic waves were applied using a bath-type ultrasonic irradiation device (100mW, TRANSSONIC T570, Elma). In this study, the surfactant concentration was constant at 0.1 mol / dm 3 above cmc. Next, the aqueous solution of gold chloride (III) acid prepared in 3-2-1 was solubilized in this C 12 (EO) 5 / cyclohexane solution. At this time, the molar ratio of water to surfactant (Rw = H 2 O / C 12 (EO) 5 ) was constant at Rw = 5, and the solubilization time was 2 hours. Rw is preferably 5-20. This is because reverse micelles cannot be maintained if R w = 20.
3-2-3 Preparation of Au fine particles by reverse micelle method For Au 3+ solubilized in the reverse micelle solution prepared in 3-2-2, reducing agents NaBH 4 are mixed with Au 3+ and NaBH 4 . Au particles were prepared in reverse micelles by adding directly to the solution so that the molar ratio was 1/5, followed by stirring at 20 ° C. for 2 hours.
3-2-4 Preparation of Au / TiO 2 composite fine particles by reverse micelle method A predetermined amount of TEOT is added to Cyclohexane, which is the outer phase of the reverse micelle solution containing Au fine particles prepared in 3-2-3, with stirring. Then, Au / TiO 2 composite fine particles were prepared by hydrolysis and condensation reaction of TEOT at the reverse micelle interface. At this time, Au and hydrolyzed substance amount ratio of TiO 2 that can be: was prepared by changing the (Au TiO 2). The reduction time was 2 hours, the hydrolysis reaction time was 24 hours, and the reaction temperature was 20 ± 1 ° C.
3-2-5 Purification of the prepared composite fine particles Centrifuge the prepared Au / TiO 2 composite fine particles: Table top high-speed cooling centrifuge (Kubota, 15000 rpm × 20 min) or centrifuge (H-108NA, Kokusan, 3500 rpm) × 30 min). The washing step of removing the supernatant and adding methanol to the precipitate and further centrifuging was repeated 5 to 6 times. The washed composite fine particles were dried under reduced pressure at 100 ° C. for 5 hours to obtain a purple powder.
３−３ Ａｕ微粒子の調製条件の検討
以上の逆ミセル法におけるAu微粒子の調製は，界面活性剤濃度を0.1 mol/dm3 一定，可溶化量をＲw = 5，可溶化時間と還元時間をそれぞれ２時間とし，反応温度20±1 ℃で行ったが、可溶化させる塩化金(III) 酸水溶液の濃度を２０mmol/dm3 〜 ４０mmol/dm3とした理由は，濃度を増加させて６０mmol/dm3以上にすると，大きなAu微粒子が形成されて沈降してしまうためである。さらに，逆ミセルに可溶化したAu3+ に対する還元剤NaBH4の物質量比 ( Au3+ : NaBH4 ) を1 : 5 とした理由は，Au3+ : NaBH4 = 1 : 5以下の範囲ではAu3+ が還元しきれず残存 ( 320 nm ) してしまうが，これ以上NaBH4を加えると生成したAu の特性吸収波長 ( 530 nm ) がブロードなピークになり，その上Au粒子が沈降してしまうためである。これに対して、Au3+: NaBH4 = 1 : 5の場合は、Au の特性吸収波長がはっきりと確認することができ，しかも安定したサスペンションとなるためである。
3-3 Examination of preparation conditions for Au fine particles Preparation of Au fine particles by the reverse micelle method described above is carried out with the surfactant concentration constant at 0.1 mol / dm 3 , the solubilization amount Rw = 5, and the solubilization time and reduction time respectively. The reaction temperature was 20 ± 1 ° C. for 2 hours. The concentration of the solubilized aqueous solution of gold (III) chloride was 20 mmol / dm 3 to 40 mmol / dm 3 because the concentration was increased to 60 mmol / dm 3. If it is 3 or more, large Au fine particles are formed and settled. Furthermore, the reason why the mass ratio of the reducing agent NaBH 4 to Au 3+ solubilized in reverse micelles (Au 3+ : NaBH 4 ) was 1: 5 is that Au 3+ : NaBH 4 = 1: 5 or less. In this case, Au 3+ cannot be fully reduced and remains (320 nm). However, when NaBH 4 is further added, the characteristic absorption wavelength (530 nm) of the generated Au becomes a broad peak, and the Au particles settle. It is because it ends up. On the other hand, when Au 3+ : NaBH 4 = 1: 5, the characteristic absorption wavelength of Au can be clearly confirmed, and the suspension becomes stable.
３−４ ＡｕとＴｉＯ2 の物質量比および調製粒子の分散状態との関係
次にＡｕとＴｉＯ2 との物質量比の関係について検討を行なった。
３−３で決定した条件でAu微粒子を逆ミセル中で調製した後に、Au微粒子を含む逆ミセル溶液にTEOT を添加し，逆ミセル中で加水分解と縮合反応させてできる TiO2 との物質量比 ( Au : TiO2 ) を変化させてAu/TiO2複合微粒子を調製した場合の複合微粒子の分散状態を図３に示す。全ての系においてAu微粒子と同じ深赤色を示した。Au3+濃度は全て，同一であるがTiO2に包含されると外観上，吸収による色が濃くなった。また，反応溶媒中でTEOTの添加量を増加させると，Au : TiO2 = 1 : 4 までは分散していたが，Au : TiO2= 1 : 6を超えたところで粒子が沈降した。この理由は，TEOTの添加量が増すことにより，加水分解して生成されるTiO2 微粒子数が多くなり，衝突，合一の結果，粒子が大きくなるためと考えられる。また，沈降物はAu微粒子と同じ深赤色を示し，Au : TiO2 = 1 : 10 以上での上澄相は透明になった。
3-4 Relationship between Au and TiO 2 Substance Ratio and Dispersed State of Prepared Particles Next, the relationship between Au and TiO 2 substance ratio was examined.
After preparing Au fine particles in reverse micelles under the conditions determined in 3-3, TEOT is added to the reverse micelle solution containing Au fine particles, and the amount of substance with TiO 2 formed by hydrolysis and condensation reaction in reverse micelles FIG. 3 shows the dispersion state of the composite fine particles when Au / TiO 2 composite fine particles are prepared by changing the ratio (Au: TiO 2 ). All systems showed the same deep red color as Au fine particles. All Au 3+ concentrations were the same, but when they were included in TiO 2 , the color due to absorption increased in appearance. When the amount of TEOT added in the reaction solvent was increased, Au: TiO 2 = 1: 4 was dispersed, but when Au: TiO 2 = 1: 6, the particles settled. The reason for this is thought to be that as the amount of TEOT added increases, the number of TiO 2 particles produced by hydrolysis increases, resulting in larger particles as a result of collision and coalescence. The sediment showed a deep red color similar to that of Au fine particles, and the supernatant phase became transparent when Au: TiO 2 = 1:10 or more.
次に，これらの系のUV‐vis 測定の結果を図４に示す。Au 微粒子は530 nm 付近にプラズモンによる特性吸収波長をもつことが確認できた。530 nmでの吸収強度は1:4が最も大きくなった。また，TEOT を添加することにより低波長側(＜350 nm)のTiO2 の吸収を確認することができた。
さらに、図３に示したように沈降が始まるAu : TiO2 = 1 : 6以上の系では，TEOT の添加量を増すにつれて溶液中でのAu微粒子が示す深赤色が薄くなるのと同時に，スペクトルでも530 nm 付近のAu の特性吸収波長とTiO2 の吸光度は低下した。以上の結果，TEOT の添加量を一定以上に増加させると，Au微粒子はTiO2微粒子に包含されて共に沈降することが分かった。
Next, Fig. 4 shows the results of UV-vis measurements for these systems. It was confirmed that Au fine particles have characteristic absorption wavelength due to plasmons around 530 nm. The absorption intensity at 530 nm was highest at 1: 4. The absorption of TiO 2 on the low wavelength side (<350 nm) was confirmed by adding TEOT.
Furthermore, as shown in Fig. 3, in the system where Au: TiO 2 = 1: 6 or more where precipitation begins, the deep red color indicated by the Au fine particles in the solution becomes thinner as the amount of TEOT added increases. However, the characteristic absorption wavelength of Au near 530 nm and the absorbance of TiO 2 decreased. As a result, it was found that when the amount of TEOT added was increased above a certain level, the Au fine particles were included in the TiO 2 fine particles and settled together.
３−５ ＴＥＭによる複合微粒子の観察
上述した逆ミセル法で調製したAu/TiO2 複合微粒子の形や大きさを調べるためにTEM 観察を行った。図５は、Au 微粒子と分散したAu : TiO2 = 1 : 1〜 1 : ２０ のTEM 写真である。まず，Au微粒子はDLS 測定では約30 nmであったが，TEM 観察では粒子径約10 nmと確認できた。20 nmほどの粒子も観察できたが，これらはサンプル作製時に水分の蒸発と共に粒子が凝集し，一つの粒子のように写ったのではないかと考えられる。
次に，TEOTの添加量を増加していくと，DLS 測定では表１に示すように粒子径が大きくなった。この差異はDLS測定が光散乱面に基づいて測定しているために生じると考えられる。TEM 観察ではAu/TiO2複合微粒子は数nmのTiO2 微粒子がAu微粒子含む構造となり，Au：TiO2＝1：4までは安定に分散した。Au：TiO2＝1：6以上では沈降がおこるが，TEMでの粒子径は約100〜200 nmとなった。また，上澄相が透明になったAu : TiO2 = 1 : 10 , 1 : 20 では上澄相中にAu微粒子の存在は確認できずTiO2微粒子のみ確認することができた。このことは、３−４で述べた、酸化チタン量の増加に伴ってAu微粒子が沈殿し、上澄みの金微粒子濃度が減少することを裏付けるものである。
3-5 Observation of composite fine particles by TEM In order to examine the shape and size of the Au / TiO 2 composite fine particles prepared by the reverse micelle method described above, TEM observation was performed. FIG. 5 is a TEM photograph of Au fine particles and dispersed Au: TiO 2 = 1: 1 to 1:20. First, the Au fine particle size was about 30 nm by DLS measurement, but it was confirmed by TEM observation that the particle size was about 10 nm. Although particles as small as 20 nm could be observed, it seems that the particles aggregated as the water evaporated during sample preparation and looked like one particle.
Next, as the amount of TEOT added was increased, the particle size increased as shown in Table 1 in the DLS measurement. This difference is considered to occur because the DLS measurement is based on the light scattering surface. According to TEM observation, the Au / TiO 2 composite fine particles had a structure in which a few nm of TiO 2 fine particles contained Au fine particles, and Au: TiO 2 = 1: 4 was stably dispersed. When Au: TiO 2 = 1: 6 or more, sedimentation occurs, but the particle size by TEM is about 100 to 200 nm. In the case of Au: TiO 2 = 1:10, 1:20 where the supernatant phase became transparent, the presence of Au particles in the supernatant phase could not be confirmed, and only TiO 2 particles could be confirmed. This supports the fact that the Au fine particles are precipitated as the amount of titanium oxide increases and the concentration of the gold fine particles in the supernatant is reduced as described in 3-4.
３−６ Au/TiO2複合微粒子の表面分析
調製したAu/TiO2複合微粒子の電子状態を調べるために，XPS測定を行った。測定に用いたサンプルは，Au : TiO2 = 1 : 10 で調製し，沈降した複合微粒子をcyclohexane で界面活性剤を洗浄，除去し乾燥させたものを用いた。図６はAu/TiO2 複合微粒子のXPS測定の結果を示す。Auの存在が確認できた。Au 4f7/2の電子状態は複合微粒子では86.6eVと83.2eVに観測された。文献より金コロイドまたは金インゴットでは87.3eVと83.8eVになり，コロイド状態でもインゴットでも変化はなかった。しかし，複合系にすると金の電子状態が変化することが認められた。この結果，図４のUV-visスペクトルでAu : TiO2 = 1 : 4で吸収強度が増加する現象にも関係していると考えられる。また，Tiは2価のTiOと4価のTiO2が存在した。この知見からも沈降した粒子にAuが含まれていることが確認できた。また，逆ミセル法で調製したTiO2微粒子についても測定を行い，その結果を図７に示した。Tiの電子状態は複合微粒子のときと変化はなかった。
To investigate the electronic states of the 3-6 Au / TiO 2 Au / TiO 2 composite fine particles subjected to surface analysis preparation of composite particles, XPS measurement was performed. The sample used for the measurement was prepared by Au: TiO 2 = 1:10, and the precipitated composite fine particles were washed with cyclohexane, removed and dried. FIG. 6 shows the result of XPS measurement of Au / TiO 2 composite fine particles. The presence of Au was confirmed. The electronic state of Au 4f7 / 2 was observed at 86.6 eV and 83.2 eV in the composite particles. From the literature, the colloidal gold or gold ingot was 87.3 eV and 83.8 eV, and there was no change in the colloidal state or ingot. However, it was found that the electronic state of gold changes when a composite system is used. As a result, it is considered that the absorption intensity increases when Au: TiO 2 = 1: 4 in the UV-vis spectrum of FIG. Further, Ti is a divalent TiO and tetravalent TiO 2 was present. From this knowledge, it was confirmed that the precipitated particles contained Au. Further, TiO 2 fine particles prepared by the reverse micelle method were also measured, and the results are shown in FIG. The electronic state of Ti was not different from that of composite particles.
３−７ Au/TiO2複合微粒子の光触媒能の検討
逆ミセル法で調製したAu/TiO2複合微粒子の光触媒能を調べるため，Au/ TiO2複合微粒子によるMOの光分解反応について検討した。測定に使用した試料は，Au：TiO2＝1：10で調製した複合微粒子を遠心分離器を用いてcyclohexaneで界面活性剤を数度洗浄後，cyclohexaneを蒸発・乾燥してから0.01 mmol/dm3 MO水溶液中に加え分散させ，光照射装置 ( 超高圧水銀ランプ，500W ) を用いて一定時間光照射した。このとき，ガラスフィルターを用いて紫外線を遮断して可視光 ( 波長500 nm以上 ) を照射した場合と，遮断せずに紫外線を含めて照射した場合によるMOスペクトルの吸光度の経時変化をUV-vis測定した。その結果を図８に示す。ガラスフィルターを用いず紫外線を照射した場合はスペクトル測定で464 nmのMO特性吸収における強度に変化が現れたが，ガラスフィルターを用いて可視光を照射した場合には変化がほとんど現れずMOに顕著な分解を見ることができなかった。
3-7 Au / TiO 2 To investigate the photocatalytic activity of the Au / TiO 2 composite fine particles prepared in consideration reverse micelle method photocatalytic ability of the composite fine particles were examined photodecomposition reaction of MO by Au / TiO 2 composite fine particles. The sample used for the measurement was 0.01 mmol / dm after the composite fine particles prepared with Au: TiO 2 = 1: 10 were washed with cyclohexane several times using a centrifuge and the cyclohexane was evaporated and dried. 3 Dispersed in an aqueous MO solution, and irradiated for a certain period of time using a light irradiation device (super high pressure mercury lamp, 500 W). At this time, changes in the absorbance of the MO spectrum over time when UV light is blocked with a glass filter and irradiated with visible light (wavelength of 500 nm or more) and when UV light is included without blocking UV-vis It was measured. The result is shown in FIG. When UV light was irradiated without using a glass filter, a change in the intensity of absorption at 464 nm of the MO characteristic was observed in the spectrum measurement, but when visible light was irradiated using a glass filter, there was almost no change and the MO was significant. I could not see any disassembly.
微粒子の表面に洗浄しきれずに付着していた界面活性剤が調製後の複合微粒子内に残存しているため，MOの光分解を妨げている可能性があると考えられる。そこで，この界面活性剤を完全に除去するため，電気炉を用いて200℃，3時間空気中で粒子を熱処理した。C12(EO)5 の界面活性剤の熱分解温度は200〜350℃である。熱処理をしたAu/TiO2複合微粒子を0.01 mmol/dm3のMO水溶液に分散させて，可視光を照射し，触媒活性能を調べた。図９はその結果を示す。図９に示すように紫外線を遮断して可視光を照射したとき464 nmにおける吸光度に変化が見られMOの光分解を確認することができた。同様に熱処理をしたAu/TiO2複合微粒子をMO水溶液に分散させ，紫外線照射による結果も図９に示した。図８の結果よりも分解速度が増大したことが認められた。すなわち，微粒子内に残存するC12(EO)5 が光分解速度に大きく影響していることがわかった。次に，この吸光度の変化がAu微粒子のプラズモンに関係があるかどうかを検討した。逆ミセル法で調製したAuを内包していないTiO2微粒子を，電気炉を用いて同様に熱処理した。そして，紫外線を遮断して可視光を照射したときのMOの分解能を調べた。図１０はその結果を示す。 It is considered that the surfactant that was not completely washed on the surface of the fine particles remained in the composite fine particles after preparation, which may have hindered the photolysis of MO. Therefore, in order to completely remove the surfactant, the particles were heat-treated in air at 200 ° C for 3 hours using an electric furnace. The thermal decomposition temperature of the C 12 (EO) 5 surfactant is 200-350 ° C. Heat-treated Au / TiO 2 composite fine particles were dispersed in 0.01 mmol / dm 3 MO aqueous solution and irradiated with visible light to investigate the catalytic activity. FIG. 9 shows the result. As shown in FIG. 9, when UV light was blocked and irradiated with visible light, the absorbance at 464 nm changed, confirming the photolysis of MO. Similarly, the heat-treated Au / TiO 2 composite fine particles are dispersed in an aqueous MO solution and the results of ultraviolet irradiation are also shown in FIG. It was recognized that the decomposition rate increased compared to the result of FIG. In other words, it was found that C 12 (EO) 5 remaining in the fine particles had a significant effect on the photolysis rate. Next, we examined whether this change in absorbance is related to the plasmons of Au particles. TiO 2 fine particles not encapsulating Au prepared by the reverse micelle method were similarly heat-treated using an electric furnace. And we investigated the resolution of MO when UV light was cut off and irradiated with visible light. FIG. 10 shows the result.
逆ミセル法で調製したTiO2微粒子は，可視光ではMOを分解しないことがわかった。その結果を図１０に比較のために示した。また，逆ミセル法で調製したAu微粒子についてもMOの分解実験を同様に行った。しかし，Au微粒子単独では全く分解が起こらなかった。これらの結果から，Au/TiO2複合微粒子はAuのプラズモンからの電子がTiO2部位を活性化することによって，可視光領域でも光触媒能を示すことを確認することができた。 It was found that TiO 2 fine particles prepared by the reverse micelle method did not decompose MO under visible light. The results are shown in FIG. 10 for comparison. The MO decomposition experiment was also conducted on Au fine particles prepared by the reverse micelle method. However, no decomposition occurred with Au fine particles alone. From these results, it was confirmed that Au / TiO 2 composite fine particles showed photocatalytic activity even in the visible light region when electrons from Au plasmons activated the TiO 2 site.
３−８ Au / TiO2複合微粒子のバンドギャップ測定
TiO2の光触媒機能はバンドギャップエネルギーが通常3.2〜3.3eVと言われている。そこで，逆ミセル法で調製したAu/TiO2複合微粒子とTiO2微粒子のバンドギャップエネルギーを測定した。
測定試料は，調製して得たAu/TiO2複合微粒子の分散液または沈殿した粒子を石英ガラス上に滴下，塗布し，乾燥して用いた。バンドギャップエネルギーは照射波長λとhνの関係式 ｈｖ＝１２４０／λ （eV）より，吸収波長をエネルギーに変換させ，吸収強度との関係から求めた。
逆ミセル法で調製したAu/TiO2複合微粒子のバンドギャップ測定の結果を表２に示す。Au : TiO2の物質量比を変化させても，バンドギャップエネルギーの値はほとんど変化しなかった。次に，逆ミセル法で調製したTiO2微粒子についてもバンドギャップ測定を行った結果，3.56eVであった。逆ミセル法で調製したAu/TiO2複合微粒子とTiO2微粒子では，バンドギャップエネルギーに大きな差がないことがわかった。
3-8 Band gap measurement of Au / TiO 2 composite fine particles
The photocatalytic function of TiO 2 is usually said to have a band gap energy of 3.2 to 3.3 eV. Therefore, the band gap energy of Au / TiO 2 composite particles and TiO 2 particles prepared by the reverse micelle method was measured.
As a measurement sample, a dispersion or precipitated particle of Au / TiO 2 composite fine particles obtained by preparation was dropped on a quartz glass, applied, and dried. The band gap energy was obtained from the relationship between the absorption intensity by converting the absorption wavelength into energy from the relational expression hv = 1240 / λ (eV) between the irradiation wavelengths λ and hν.
Table 2 shows the results of band gap measurement of Au / TiO 2 composite fine particles prepared by the reverse micelle method. Even when the mass ratio of Au: TiO 2 was changed, the value of the band gap energy hardly changed. Next, TiO 2 fine particles prepared by the reverse micelle method were 3.56 eV as a result of band gap measurement. It was found that there was no significant difference in band gap energy between Au / TiO 2 composite particles and TiO 2 particles prepared by the reverse micelle method.
以上の結果から，Au/TiO2複合微粒子が可視光領域で光触媒能を示すのは，TiO2部位のバンドギャップエネルギー変化によるものではないことを明らかにすることができた。 From the above results, it was clarified that Au / TiO 2 composite fine particles exhibit photocatalytic activity in the visible light region is not due to a change in the band gap energy at the TiO 2 site.
３−９ まとめ
以上の検討により、以下のような結論が得られた。
１） 逆ミセル法によりＡｕ微粒子が内包されたＡｕ／酸化チタン複合微粒子を調製することができた。
２） ＸＰＳ測定から、複合微粒子中のＡｕの電子状態は、Ａｕコロイドやインゴットの状態における電子状態と異なることがわかった。
３） 複合微粒子は焼かなくても紫外線なら光触媒活性を持つことがわかった。
４） Ａｕ／酸化チタン複合微粒子は、Ａｕのプラズモンからの電子がTiO2 部位を活性化することによって、可視光領域でも光触媒能を示すことが確認された。
５） 複合微粒子中の酸化チタンのバンドギャップエネルギー値は酸化チタン単独微粒子の値とほぼ同じであった。
3-9 Summary The following conclusions were obtained from the above study.
1) Au / titanium oxide composite fine particles encapsulating Au fine particles could be prepared by the reverse micelle method.
2) From XPS measurement, it was found that the electronic state of Au in the composite fine particles is different from the electronic state in the state of Au colloid or ingot.
3) It was found that the composite fine particles have photocatalytic activity if they are ultraviolet rays even if they are not baked.
4) It was confirmed that Au / titanium oxide composite fine particles exhibit photocatalytic activity even in the visible light region when electrons from plasmons of Au activate TiO 2 sites.
5) The band gap energy value of titanium oxide in the composite fine particles was almost the same as the value of titanium oxide single fine particles.
４ ルート２について
４−１ Au/TiO2 複合微粒子の調製手順
図１１に示されるように、このルートで提案される調製方法は、予め調製されたＡｕ微粒子分散溶液を逆ミセル中に可溶化させるステップと、続いてＡｕ微粒子含有逆ミセル溶液へＴＥＯＴを滴下して逆ミセル界面で加水分解と縮合反応させるステップとにより、金微粒子を酸化チタンで包摂した複合微粒子を調製するものである。
4 About Route 2 4-1 Preparation Procedure of Au / TiO 2 Composite Fine Particles As shown in FIG. 11, the preparation method proposed in this route is to solubilize a previously prepared Au fine particle dispersion in reverse micelles. The composite microparticles in which the gold microparticles are encapsulated with titanium oxide are prepared by the step and the step of dropping TEOT into the Au microparticle-containing reverse micelle solution and causing the hydrolysis and condensation reaction at the reverse micelle interface.
４−２ 試薬の調製
４−２−１ Ａｕ微粒子分散液の調製
Ａｕ微粒子分散液を、３−１で調製された４０mmol/dm3 塩化金（III）酸水溶液を用いて純水で希釈した後に、オイルバス中で加熱した。溶液が沸騰を開始したところで、還元剤として５．０wt% クエン酸ナトリウム水溶液をＡu3+とクエン酸ナトリウムのモル比が１／２．１となるように加え、３０分間加熱還流を行ない、Ａｕ微粒子分散液を調製した。
４−２−２ 逆ミセル溶液の調製
界面活性剤 C12(EO)5を Cyclohexane に溶解させ，0.1 mol/dm3 のC12(EO)5/ Cyclohexane 溶液を調製した。この際，均一溶解を早めるためにバス型超音波照射装置 ( 100mW, TRANSSONIC T570, Elma ) を用いて，超音波を照射した。本研究では，界面活性剤濃度は cmc 以上の 0.1 mol/ dm3 で一定とした。次に，このC12(EO)5/cyclohexane 溶液に４−２−１で調製された金微粒子水溶液を可溶化した。このとき，界面活性剤に対する水のモル比 ( H2O/ C12(EO)5 ) をＲwで表しＲw = 5〜20とし，可溶化時間を２時間とした。
４−２−３ 逆ミセル法によるAu/TiO 2 複合微粒子の調製
４−２−２で調製された Au 微粒子を含有した逆ミセル溶液の外相である Cyclohexane に所定量の TEOT を撹拌しながら添加し，逆ミセル界面で TEOT を加水分解と縮合反応させることにより Au/TiO2 複合微粒子を調製した。このとき， Au と加水分解してできる TiO2 の物質量比 ( Au : TiO2 ) を変化させて調製した。還元時間を２時間，加水分解反応時間を24時間，反応温度を20±1℃ とした。
４−２−４ 調製された複合微粒子の精製
調製されたAu/TiO2 複合微粒子を遠心分離機：テーブルトップ高速冷却遠心器（クボタ、15000rpm×20min）もしくは遠心器（Ｈ−１０８ＮＡ，コクサン、3500rpm×30min）を用いて遠心分離した。上澄みを除去し、沈殿物へMethanolを加えてさらに遠心分離を行なう洗浄工程を５〜６度繰り返した。洗浄した複合微粒子を減圧下100℃×５時間乾燥し、紫色の粉末を得た。
尚、上述において、Ａｕ微粒子分散溶液は０．２５wt% のものを用い、添加するＴＥＯＴとＡｕ微粒子のモル比（Ａｕ／ＴＥＯＴ）を１／１，１／２，１／４，１／６，１／８，１／１０，１／２０，１／３０，１／５０，１／１００と変化させて、Ａｕ／酸化チタン複合微粒子を調製した結果、１／１０までは調製後の溶液がＡｕ微粒子のプラズモンに起因する紫色の均一な分散液であったのに対し、１／２０以上の比で分散系が非常に不安定になり、紫色の沈殿が生じた。上澄み溶液は透明であった。
Ａｕ／ＴＥＯＴ＝１／１０のものを試料として用い、遠心分離とエタノール洗浄を繰り返し、１００℃５時間の乾燥により精製した。
4-2 Preparation of reagents
4-2-1 Preparation of Au fine particle dispersion The Au fine particle dispersion was diluted with pure water using the 40 mmol / dm 3 chloroauric (III) chloride aqueous solution prepared in 3-1, and then heated in an oil bath. did. When the solution started to boil, a 5.0 wt% sodium citrate aqueous solution was added as a reducing agent so that the molar ratio of Au 3+ and sodium citrate was 1 / 2.1, and the mixture was heated to reflux for 30 minutes. A fine particle dispersion was prepared.
4-2-2 Preparation of reverse micelle solution Surfactant C 12 (EO) 5 was dissolved in cyclohexane to prepare a 0.1 mol / dm 3 C12 (EO) 5 / Cyclohexane solution. At this time, in order to accelerate uniform dissolution, ultrasonic waves were applied using a bath-type ultrasonic irradiation device (100mW, TRANSSONIC T570, Elma). In this study, the surfactant concentration was constant at 0.1 mol / dm 3 above cmc. Next, the gold fine particle aqueous solution prepared in 4-2-1 was solubilized in this C 12 (EO) 5 / cyclohexane solution. At this time, the molar ratio of water to surfactant (H 2 O / C 12 (EO) 5 ) was represented by Rw, Rw = 5 to 20, and the solubilization time was 2 hours.
4-2-3 Preparation of Au / TiO 2 composite fine particles by reverse micelle method A predetermined amount of TEOT is added to Cyclohexane, which is the outer phase of the reverse micelle solution containing Au fine particles prepared in 4-2-2, with stirring. Then, Au / TiO 2 composite fine particles were prepared by hydrolysis and condensation reaction of TEOT at the reverse micelle interface. At this time, Au and hydrolyzed substance amount ratio of TiO 2 that can be: was prepared by changing the (Au TiO 2). The reduction time was 2 hours, the hydrolysis reaction time was 24 hours, and the reaction temperature was 20 ± 1 ° C.
4-2-4 Purification of the prepared composite fine particles Centrifuge the prepared Au / TiO 2 composite fine particles: Table top high-speed cooling centrifuge (Kubota, 15000 rpm × 20 min) or centrifuge (H-108NA, Kokusan, 3500 rpm) × 30 min). The washing step of removing the supernatant and adding methanol to the precipitate and further centrifuging was repeated 5 to 6 times. The washed composite fine particles were dried under reduced pressure at 100 ° C. for 5 hours to obtain a purple powder.
In the above, the Au fine particle dispersion solution is 0.25 wt%, and the molar ratio (Au / TEOT) of TEOT to be added and Au fine particles is 1/1, 1/2, 1/4, 1/6, As a result of preparing Au / titanium oxide composite fine particles by changing to 1/8, 1/10, 1/20, 1/30, 1/50, 1/100, the solution after preparation was Au until 1/10. While it was a purple uniform dispersion due to fine particle plasmons, the dispersion became very unstable at a ratio of 1/20 or more, resulting in a purple precipitate. The supernatant solution was clear.
A sample of Au / TEOT = 1/10 was used as a sample, and centrifugation and ethanol washing were repeated, followed by purification by drying at 100 ° C. for 5 hours.
４−３ ルート２で得られた複合微粒子の性状
４−３−１ 紫外可視吸収スペクトル
複合微粒子調製前後の紫外可視スペクトルを測定した結果を図１２に示す。
Ａｕ微粒子のみ、即ち複合化前のサンプルでは、５００〜６００ｎｍにわずかなピークが見られる。これは、Ａｕ微粒子に特徴的なプラズモン吸収に起因するものである。これに対して、複合微粒子では、Ａｕ微粒子のプラズモン吸入が保たれたまま、３５０ｎｍ以下の波長域で急峻な吸収が現れた。この吸収は、酸化チタン成分に由来するものであり、Ａｕ微粒子と酸化チタンとが何らかの形で複合していると考えられる。
4-3 Properties of Composite Fine Particles Obtained by Route 2 4-3-1 Ultraviolet-Visible Absorption Spectrum FIG. 12 shows the results of measuring the UV-visible spectrum before and after preparation of the composite fine particles.
In the Au fine particle alone, that is, the sample before complexation, a slight peak is observed at 500 to 600 nm. This is due to the plasmon absorption characteristic of Au fine particles. In contrast, in the composite fine particles, steep absorption appeared in the wavelength region of 350 nm or less while the plasmon inhalation of the Au fine particles was maintained. This absorption is derived from the titanium oxide component, and it is considered that Au fine particles and titanium oxide are combined in some form.
４−３−２ ラマン散乱スペクトル
一般に、ルチル型酸化チタンとアナターゼ型酸化チタンのラマン散乱スペクトルは、６００ｃｍ-1 付近にそれぞれの結晶型に特有のピークを有する。従って、ラマン散乱を用いて酸化チタンの結晶型を判別することができるので、複合微粒子のラマン散乱スペクトルを測定することで、酸化チタン層の結晶型の同定を試みた。
得られたスペクトルをルチル型酸化チタン、アナターゼ型酸化チタン、及び逆ミセル法で調製された酸化チタンと比較した。比較結果を図１３に示す。複合微粒子のそれは、ルチル型酸化チタンのピークに近いものの完全には一致せず、また逆ミセル法で調製した酸化チタンのスペクトルとも一致しなかった。これは、極微少な領域（結晶径よりも小さいスケール）においても、純粋な酸化チタンの結晶格子中の原子間の結合モード（ラマン散乱の場合は分極率の違い）と今回得られた複合微粒子のそれとは微妙に異なっていることを意味している。即ち、Ａｕ微粒子と酸化チタン微粒子のマクロスケールの混合物ではなく、少なくともナノスケールで両者が混合しているものと示唆される。
4-3-2 Raman Scattering Spectrum Generally, the Raman scattering spectra of rutile type titanium oxide and anatase type titanium oxide have peaks peculiar to respective crystal types in the vicinity of 600 cm −1 . Therefore, since the crystal form of titanium oxide can be discriminated using Raman scattering, an attempt was made to identify the crystal form of the titanium oxide layer by measuring the Raman scattering spectrum of the composite fine particles.
The obtained spectra were compared with rutile titanium oxide, anatase titanium oxide, and titanium oxide prepared by the reverse micelle method. The comparison results are shown in FIG. Although it was close to the peak of the rutile type titanium oxide, it did not completely match that of the composite fine particles, and also did not match the spectrum of titanium oxide prepared by the reverse micelle method. Even in a very small region (scale smaller than the crystal diameter), the bonding mode between atoms in the crystal lattice of pure titanium oxide (difference in polarizability in the case of Raman scattering) and the composite fine particles obtained this time It means that it is slightly different. That is, it is suggested that the mixture is not a macro-scale mixture of Au fine particles and titanium oxide fine particles but at least nano-scale.
４−３−３ ＴＧ−ＤＴＡ測定
調製された複合微粒子の熱分析結果を図１４に示す。
複合微粒子の熱分析測定により、昇温開始直後から５００℃近辺にかけて重量減少が観測された。このうち、一般に２００℃までの重量減少は、脱水と粒子中に残存していたアルコキシ基の縮合によるものと考えられる。２００℃〜３５０℃にかけての重量減少は、その温度領域がC12(EO)5 の分解温度と一致することから、複合微粒子中に残存するC12(EO)5によるものと考えられる。
4-3-3 TG-DTA Measurement FIG. 14 shows the thermal analysis results of the prepared composite fine particles.
As a result of thermal analysis measurement of the composite fine particles, a decrease in weight was observed from immediately after the start of temperature increase to around 500 ° C. Of these, the weight loss up to 200 ° C. is generally considered to be due to dehydration and condensation of alkoxy groups remaining in the particles. Weight loss over the 200 ° C. to 350 ° C., since the temperature region coincides with the decomposition temperature of the C 12 (EO) 5, is thought to be due to C 12 (EO) 5 remaining in the composite fine particles.
４−３−４ ＴＥＭ観察
調製された複合微粒子の形状をＴＥＭを用いて観察した。複合微粒子調製直後の逆ミセル溶液を、ＴＥＭの銅メッシュ上にサンプリングしたものを用いた。図１５に示されるように、複合微粒子はほぼ球形であった。画像を基に１００個の粒子の粒子径を測り、その平均を求めたところ、平均粒子径は約７．５ｎｍであった。原料である０．２５wt%Ａｕ微粒子分散溶液の粒径分布と比較した結果、全体的に約０．６ｎｍ粒子径が増大していた。粒子径の増加分が複合化された酸化チタンによるものと仮定すると、ＡｕとＴＥＯＴのモル比が１／１０の複合微粒子においては、Ａｕ微粒子は約０．３ｎｍの酸化チタン層で覆われていると考えられる。
4-3-4 TEM Observation The shape of the prepared composite fine particles was observed using a TEM. The reverse micelle solution immediately after preparation of the composite fine particles was sampled on a TEM copper mesh. As shown in FIG. 15, the composite fine particles were almost spherical. When the particle diameter of 100 particles was measured based on the image and the average was determined, the average particle diameter was about 7.5 nm. As a result of comparison with the particle size distribution of the 0.25 wt% Au fine particle dispersion solution as a raw material, the particle size was increased by about 0.6 nm as a whole. Assuming that the increase in the particle size is due to the composite titanium oxide, in the composite fine particles having a molar ratio of Au to TEOT of 1/10, the Au fine particles are covered with a titanium oxide layer of about 0.3 nm. it is conceivable that.
４−３−５ 複合微粒子の光触媒活性
高圧水銀灯の２９０ｎｍ以下の波長を、Pyrexフィルターでカットした光源を用いた。０min，１５min，３０min，４５min，６０min，９０min，１２０min，１５０min後に反応溶液を０．５ｍｌサンプリングした。試料を０．２μｍＰＴＦＥメンブランフィルターでろ過し、ＨＰＬＣで分析して各時間におけるＲｈＢの濃度を測定した。得られた結果を反応開始時（０min）の値で除し残存率としてプロットした。ＵＶ照射における光触媒反応の結果を図１６に示す。ここで、２９０ｎｍ以下の波長をカットしたのは、ＲｈＢは２９０ｎｍ以下の波長の光を強く吸収し、光分解反応を受けるためである。
上述した結果から分かるように、紫外光を含んだ光照射の実験では、ＳＴ−０１の活性が複合微粒子よりも高かった。これは、酸化チタンの吸収波長である２９０〜３００ｎｍが主に光触媒に作用したためであり、その作用はより純粋な酸化チタンであるＳＴ−０１の方が高いことによるものである。複合微粒子の値はブランクよりもずっと小さいことから、紫外線を含んだ光の照射による光触媒の作用が確認できるが、その作用がＳＴ−０１と同様の酸化チタンの光キャリア生成（２９０〜３００ ｎｍ）によるものなのか、Ａｕ微粒子のプラズモン吸収（５００〜６００ｎｍ）によるものなのかは、この実験では判断できない。そこで、酸化チタンのバンドギャップエネルギーよりも低いエネルギーの波長、即ち、４５０ｎｍ以上の波長の光を照射して、光触媒活性を評価した。可視光照射における光触媒反応の結果を図１７に示す。ＵＶ照射と可視光照射下における１２０ｍｉｎ後の基質残存率を表３にまとめた。
4-3-5 Photocatalytic activity of composite fine particles A light source obtained by cutting a wavelength of 290 nm or less of a high-pressure mercury lamp with a Pyrex filter was used. After 0 min, 15 min, 30 min, 45 min, 60 min, 90 min, 120 min, and 150 min, 0.5 ml of the reaction solution was sampled. The sample was filtered through a 0.2 μm PTFE membrane filter and analyzed by HPLC to measure the concentration of RhB at each time. The obtained results were divided by the value at the start of the reaction (0 min) and plotted as the residual rate. The result of the photocatalytic reaction in UV irradiation is shown in FIG. Here, the reason why the wavelength of 290 nm or less was cut is that RhB strongly absorbs light having a wavelength of 290 nm or less and undergoes a photolysis reaction.
As can be seen from the results described above, in the experiment of light irradiation including ultraviolet light, the activity of ST-01 was higher than that of the composite fine particles. This is because 290 to 300 nm, which is the absorption wavelength of titanium oxide, mainly acts on the photocatalyst, and this action is due to the higher purity of ST-01, which is a purer titanium oxide. Since the value of the composite fine particles is much smaller than that of the blank, the action of the photocatalyst by irradiation with light containing ultraviolet rays can be confirmed, but the action is the same as ST-01 for photocatalytic generation of titanium oxide (290 to 300 nm). Whether it is due to plasmon absorption (500 to 600 nm) of Au fine particles cannot be determined in this experiment. Therefore, the photocatalytic activity was evaluated by irradiating light having a wavelength lower than the band gap energy of titanium oxide, that is, a wavelength of 450 nm or more. The result of the photocatalytic reaction in visible light irradiation is shown in FIG. Table 3 summarizes the residual ratio of the substrate after 120 min under UV irradiation and visible light irradiation.
ＲｈＢのみの値が、ＲｈＢ自身が光照射によって分解されたことによるバックグランド値である。ＳＴ−０１の値がバックグランド値とほぼ一致していることから、ＳＴ−０１の可視光による光触媒活性は非常に小さい。これに対して、今回得られた複合微粒子のその値は、バックグランド及びＳＴ−０１の両方よりもずっと小さい値であることから、可視光照射下において光触媒活性を示していることが確認された。 The value of only RhB is the background value resulting from the decomposition of RhB itself by light irradiation. Since the value of ST-01 almost coincides with the background value, the photocatalytic activity of ST-01 by visible light is very small. On the other hand, since the value of the composite fine particles obtained this time was much smaller than both the background and ST-01, it was confirmed that the photocatalytic activity was exhibited under visible light irradiation. .
４−４ まとめ
以上の検討により、予め調製されたＡｕ微粒子分散溶液を逆ミセル中へ可溶化し、ＴＥＯＴを加えて逆ミセル界面で加水分解と縮合反応することにより、Ａｕ／酸化チタン複合微粒子が調製され、ＡｕとＴＥＯＴのモル比が１／１０で得られた複合微粒子において、以下のような結論が得られた。
１） ＴＥＭ像により平均粒子径７．５ｎｍのほぼ球形の粒子であり、Ａｕ微粒子表面が０．３ｎｍの酸化チタン層で覆われていた。
２） 得られた複合微粒子はナノレベルでＡｕ微粒子と複合しているため、ラマン散乱スペクトルから、酸化チタン成分はルチル型ともアナターゼ型とも一致しない特徴的なスペクトルを有した。
３） ４５０ｎｍ以下をカットした可視光下において光触媒活性を示した。
したがって、可視光応答酸化チタン光触媒として機能するＡｕ／酸化チタン複合微粒子は、ルート２においても生成可能であり、このルート２の製法は、Ａｕ微粒子の調製条件が温和且つ簡便であることから、前述したルート１の製法と比較して、より調製しやすい方法である。
4-4 Summary By the above examination, Au / titanium oxide composite fine particles can be obtained by solubilizing a previously prepared Au fine particle dispersion in reverse micelles and adding TEOT to hydrolysis and condensation reaction at the reverse micelle interface. The following conclusions were obtained for the composite fine particles prepared and obtained at a molar ratio of Au to TEOT of 1/10.
1) It was a substantially spherical particle having an average particle diameter of 7.5 nm according to a TEM image, and the Au fine particle surface was covered with a 0.3 nm titanium oxide layer.
2) Since the obtained composite fine particles were complexed with Au fine particles at the nano level, the titanium oxide component had a characteristic spectrum that did not match the rutile type or the anatase type from the Raman scattering spectrum.
3) Photocatalytic activity was shown under visible light with a wavelength of 450 nm or less cut.
Therefore, Au / titanium oxide composite fine particles functioning as a visible light responsive titanium oxide photocatalyst can be produced also in Route 2, and the production method of Route 2 is described above because the preparation conditions of Au fine particles are mild and simple. Compared with the route 1 manufacturing method, it is easier to prepare.
以上述べたように、上述した２つのルートを用いてＡｕ微粒子が酸化チタン層で包摂された複合微粒子を調製することで、Ａｕ微粒子のプラズモン電子を酸化チタンの活性化に用いた可視光で作用する光触媒を創製することが可能となった。 As described above, by preparing composite fine particles in which Au fine particles are included in the titanium oxide layer using the above-described two routes, the plasmon electrons of the Au fine particles act on the visible light used to activate the titanium oxide. It has become possible to create a photocatalyst that does this.
可視光活性光触媒機能を持つ微粒子材料や、紫外線活性化光触媒に代わる多方面における有機物を光分解させる材料等に使用可能である。 It can be used for a fine particle material having a visible light active photocatalyst function, a material for photodegrading organic substances in various fields instead of an ultraviolet light activated photocatalyst, and the like.
Claims (9)
この可溶化させた金イオンに対し、還元剤を所定の比で添加し、攪拌することで逆ミセルまたは逆マイクロエマルション中に金コロイドを調製する工程と、
前記金コロイドを含有した逆ミセルの外相の炭化水素油に所定量の有機チタン錯体を添加して加水分解と縮合反応させることで前記金コロイドを酸化チタン層で包摂する工程とを含むことを特徴とする可視光感応型光触媒の調製方法。 Dissolving a nonionic amphiphile having an HLB of 10 to 16 in a solvent comprising a hydrocarbon oil having a carbon chain length of 5 to 16, and solubilizing a water-soluble gold salt in the solution;
A step of adding a reducing agent to the solubilized gold ion in a predetermined ratio and stirring the mixture to prepare a gold colloid in reverse micelle or reverse microemulsion,
Including a step of adding a predetermined amount of an organic titanium complex to a hydrocarbon oil of the outer phase of the reverse micelle containing the gold colloid and causing the hydrolysis and condensation reaction to include the gold colloid in a titanium oxide layer. A method for preparing a visible light sensitive photocatalyst.
非イオン性界面活性剤を炭素数５〜１６の炭化水素油からなる溶媒中に溶解させ、この溶液に前記金微粒子分散溶液を可溶化させる工程と、
前記金微粒子を含有した逆ミセルの外相の炭化水素油に所定量の有機チタン錯体を添加して加水分解と縮合反応させることで前記金微粒子を酸化チタン層で包摂する工程と
を含むことを特徴とする可視光感応型光触媒の調製方法。 A step of preparing a gold fine particle dispersion in advance;
Dissolving a nonionic surfactant in a solvent comprising a hydrocarbon oil having 5 to 16 carbon atoms, and solubilizing the gold fine particle dispersion in this solution;
Including a step of adding a predetermined amount of an organic titanium complex to a hydrocarbon oil of the outer phase of the reverse micelle containing the gold fine particles and causing the hydrolysis and condensation reaction to include the gold fine particles in a titanium oxide layer. A method for preparing a visible light sensitive photocatalyst.
9. The particle in which the gold fine particles are included in a titanium oxide layer is taken out and heat-treated at a temperature higher than the decomposition temperature of the nonionic surfactant and lower than the anatase conversion temperature of titanium oxide. A method for preparing the visible light-sensitive photocatalyst as described.
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| JP2008264611A (en) * | 2007-04-16 | 2008-11-06 | National Institute Of Advanced Industrial & Technology | Photocatalyst structure |
| KR101249885B1 (en) * | 2011-03-16 | 2013-04-03 | 한국광기술원 | Photocatalyst water purifier using plasmon |
| EP2774675A1 (en) | 2013-03-07 | 2014-09-10 | Kanagawa University | Method for preparing visible light-responsive photocatalyst and visible light-responsive photocatalyst intermediate |
| JP2015016466A (en) * | 2013-06-21 | 2015-01-29 | 台北医学大学 | Water treating apparatus and process for preparation of fine water cluster and fine water cluster prepared with the apparatus or process |
| JP2017012999A (en) * | 2015-07-01 | 2017-01-19 | 国立大学法人大阪大学 | Gold-cerium oxide complex catalyst and selective hydrogenation method using the catalyst |
| WO2019078100A1 (en) * | 2017-10-16 | 2019-04-25 | 国立大学法人山形大学 | Method for producing composite including metal coated with solid microparticles |
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| JP2008264611A (en) * | 2007-04-16 | 2008-11-06 | National Institute Of Advanced Industrial & Technology | Photocatalyst structure |
| WO2008133007A1 (en) * | 2007-04-16 | 2008-11-06 | National Institute Of Advanced Industrial Science And Technology | Photocatalyst structure |
| KR101249885B1 (en) * | 2011-03-16 | 2013-04-03 | 한국광기술원 | Photocatalyst water purifier using plasmon |
| EP2774675A1 (en) | 2013-03-07 | 2014-09-10 | Kanagawa University | Method for preparing visible light-responsive photocatalyst and visible light-responsive photocatalyst intermediate |
| JP2014195797A (en) * | 2013-03-07 | 2014-10-16 | 学校法人神奈川大学 | Preparation method of visible light-responsive photocatalyst and visible light-responsive photocatalyst intermediate, usage of visible light-responsive photocatalyst, and visible light-responsive photocatalyst |
| US10040056B2 (en) | 2013-03-07 | 2018-08-07 | Kanagawa University | Method for preparing visible light-responsive photocatalyst and visible light-responsive photocatalyst intermediate |
| JP2015016466A (en) * | 2013-06-21 | 2015-01-29 | 台北医学大学 | Water treating apparatus and process for preparation of fine water cluster and fine water cluster prepared with the apparatus or process |
| US10661003B2 (en) | 2013-06-21 | 2020-05-26 | Taipei Medical University | Apparatus and process for preparation of small water cluster and small molecular cluster water prepared therefrom |
| JP2017012999A (en) * | 2015-07-01 | 2017-01-19 | 国立大学法人大阪大学 | Gold-cerium oxide complex catalyst and selective hydrogenation method using the catalyst |
| WO2019078100A1 (en) * | 2017-10-16 | 2019-04-25 | 国立大学法人山形大学 | Method for producing composite including metal coated with solid microparticles |
| JPWO2019078100A1 (en) * | 2017-10-16 | 2020-12-17 | 国立大学法人山形大学 | Method for Producing Complex Containing Metal Coated with Solid Fine Particles |
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