JP4660766B2 - Visible light responsive complex oxide photocatalyst - Google Patents
Visible light responsive complex oxide photocatalyst Download PDFInfo
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- JP4660766B2 JP4660766B2 JP2006045933A JP2006045933A JP4660766B2 JP 4660766 B2 JP4660766 B2 JP 4660766B2 JP 2006045933 A JP2006045933 A JP 2006045933A JP 2006045933 A JP2006045933 A JP 2006045933A JP 4660766 B2 JP4660766 B2 JP 4660766B2
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- 239000000126 substance Substances 0.000 claims description 35
- 238000000034 method Methods 0.000 claims description 29
- 239000004065 semiconductor Substances 0.000 claims description 26
- 229910052739 hydrogen Inorganic materials 0.000 claims description 17
- 239000001257 hydrogen Substances 0.000 claims description 17
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 16
- 239000000203 mixture Substances 0.000 claims description 11
- 238000004140 cleaning Methods 0.000 claims description 9
- 230000001678 irradiating effect Effects 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 150000001875 compounds Chemical class 0.000 claims description 4
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- 239000002131 composite material Substances 0.000 description 19
- 230000000694 effects Effects 0.000 description 19
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- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 17
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 15
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- 229910010413 TiO 2 Inorganic materials 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
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- 229910052715 tantalum Inorganic materials 0.000 description 2
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- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
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- 229910000464 lead oxide Inorganic materials 0.000 description 1
- 230000004298 light response Effects 0.000 description 1
- OUHCLAKJJGMPSW-UHFFFAOYSA-L magnesium;hydrogen carbonate;hydroxide Chemical compound O.[Mg+2].[O-]C([O-])=O OUHCLAKJJGMPSW-UHFFFAOYSA-L 0.000 description 1
- 229910001510 metal chloride Inorganic materials 0.000 description 1
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- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910000484 niobium oxide Inorganic materials 0.000 description 1
- URLJKFSTXLNXLG-UHFFFAOYSA-N niobium(5+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Nb+5].[Nb+5] URLJKFSTXLNXLG-UHFFFAOYSA-N 0.000 description 1
- 229910017464 nitrogen compound Inorganic materials 0.000 description 1
- 150000002830 nitrogen compounds Chemical class 0.000 description 1
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- 230000003647 oxidation Effects 0.000 description 1
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- YEXPOXQUZXUXJW-UHFFFAOYSA-N oxolead Chemical compound [Pb]=O YEXPOXQUZXUXJW-UHFFFAOYSA-N 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
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- 229910052721 tungsten Inorganic materials 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
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
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- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
Description
本発明は光触媒材料とこの触媒の用途ならびにこの触媒を用いた有害物質の分解方法、汚れ物質分解清浄化方法、及び水素発生方法に関する。詳しくは、太陽光、室内照明などに含まれる紫外線は勿論、紫外線以外の可視光線に対しても高い光触媒活性を示す複合酸化物型光触媒材料とこの触媒の用途ならびにこの触媒を用いた有害物質の分解方法、汚れ物質分解清浄化方法、及び水素発生方法に関する。 The present invention relates to a photocatalytic material, the use of this catalyst, a method for decomposing harmful substances, a method for decomposing and purifying soiled substances, and a method for generating hydrogen. Specifically, composite oxide photocatalyst materials exhibiting high photocatalytic activity for visible light other than ultraviolet rays as well as ultraviolet rays contained in sunlight and indoor lighting, the use of this catalyst, and harmful substances using this catalyst. The present invention relates to a decomposition method, a dirty material decomposition cleaning method, and a hydrogen generation method.
光触媒は、そのバンドギャップ以上のエネルギーを有する光が照射されると価電子帯の電子が伝導帯に励起され、伝導帯、価電子帯にそれぞれ電子、ホールを生成する。特にホールは強い酸化力を持ち、さまざまな有機物質を酸化分解することができ、脱臭や抗菌などさまざまな分野に応用されている。 When the photocatalyst is irradiated with light having energy greater than its band gap, electrons in the valence band are excited to the conduction band, and electrons and holes are generated in the conduction band and the valence band, respectively. In particular, halls have strong oxidizing power, can oxidize and decompose various organic substances, and are applied to various fields such as deodorization and antibacterial.
このような光触媒として機能しえる典型的な実用材料としては、これまで主として酸化チタンが知られている(非特許文献1)。しかしながら、酸化チタンのバンドギャップは3.2eVと大きいため400nmより短い波長の紫外光に対しては極めて高い光触媒活性を示すことが知られているが、これより波長の長い波長領域、すなわち可視光領域の光に対して活性を示すことはなかった。 As a typical practical material that can function as such a photocatalyst, titanium oxide has been mainly known so far (Non-patent Document 1). However, since the band gap of titanium oxide is as large as 3.2 eV, it is known that it exhibits extremely high photocatalytic activity for ultraviolet light having a wavelength shorter than 400 nm. There was no activity against the light in the region.
光源となる太陽光や蛍光灯に含まれている紫外線の量は、可視光の約4〜10%しかない。換言すれば、自然光の大部分は可視光で占められており、従来の酸化チタンを光触媒として使用する限りにおいては、自然光の光スペクトルの大部分を占める可視光領域の部分は、全く利用されることがないままに無駄になる。そのため、光の利用効率は極端に低く、特に光の絶対量が少ない、室内においては光触媒技術・材料がほとんど利用されるまでに至っていない。 The amount of ultraviolet rays contained in sunlight and fluorescent lamps that are light sources is only about 4 to 10% of visible light. In other words, most of the natural light is occupied by visible light, and as long as conventional titanium oxide is used as a photocatalyst, the part of the visible light region that occupies most of the light spectrum of natural light is completely utilized. It will be wasted without anything. For this reason, the light utilization efficiency is extremely low, and the photocatalyst technology / materials are hardly used in the room where the absolute amount of light is particularly small.
それゆえ、光の絶対量が少ない室内空間においても機能する可視光応答型の光触媒材料の開発が期待されている。このような状況から、近年、可視光領域の波長に対しても活性を示す各種光触媒が提案され、開発されている。 Therefore, the development of a visible light responsive photocatalytic material that functions even in an indoor space with a small absolute amount of light is expected. Under these circumstances, in recent years, various photocatalysts that are active even at wavelengths in the visible light region have been proposed and developed.
たとえば、その一つに、酸化チタンにCrやVなどの金属イオンをドープすることによって、可視光に対しても触媒活性を発現しうる触媒が提案されている(非特許文献2)。この提案によるとCrやVなどの金属イオンがドープされることによって、酸化チタンの伝導帯と価電子帯の間にエネルギー準位が新たに作り出され、バンドギャップが狭窄し、確かに可視光を吸収することができるようになる。しかしながら、金属イオンのドープによって導入されたエネルギー準位は電子とホールの再結合サイトにもなりえ、活性の上昇がそれほどには期待することができなかった。 For example, as one of them, a catalyst that can exhibit catalytic activity even for visible light by doping titanium oxide with metal ions such as Cr and V has been proposed (Non-patent Document 2). According to this proposal, by doping metal ions such as Cr and V, a new energy level is created between the conduction band and the valence band of titanium oxide, the band gap is narrowed, and visible light is certainly generated. Be able to absorb. However, the energy level introduced by doping metal ions can also be a recombination site of electrons and holes, and the increase in activity could not be expected so much.
これに対して、酸化チタンに窒素などのアニオンをドープすることによって可視光応答型光触媒材料を作製することが提案されている(特許文献1)。この提案による酸化チタン光触媒は、金属イオンドープ型光触媒よりも確かに可視光照射下における活性は上昇するが、窒素をドープすることによって酸化チタン内部に酸素欠陥が作製され、光触媒活性が低下してしまうという欠点があった。何れにしてもドープという手法を用いることによって作製されてなる可視光応答型光触媒材料は、現段階ではその活性はまだ不十分であり、更に一段と高いレベルの光触媒活性を発現しうる触媒が求められている。 On the other hand, it has been proposed to produce a visible light responsive photocatalytic material by doping titanium oxide with an anion such as nitrogen (Patent Document 1). The titanium oxide photocatalyst produced by this proposal has a higher activity under visible light irradiation than the metal ion doped photocatalyst. However, doping with nitrogen creates oxygen defects inside the titanium oxide, reducing the photocatalytic activity. There was a drawback of end. In any case, the visible light responsive photocatalyst material produced by using the dope method is still insufficient in activity at this stage, and there is a need for a catalyst that can express a higher level of photocatalytic activity. ing.
最近では、酸化チタン以外の酸化物によって可視光応答型光触媒を設計し、作製する試
みが提案されている。例えば、一般式In1-xMxAO4(Mは遷移金属元素を、Aは周期
律表第5a元素を、xは0<x<1の数を表す。)で表されるインジウム(In)含有複合酸化物半導体によって可視光応答型光触媒を設計することが提案されている(特許文献2)。
Recently, an attempt to design and manufacture a visible light responsive photocatalyst using an oxide other than titanium oxide has been proposed. For example, indium represented by the general formula In 1-x M x AO 4 (M represents a transition metal element, A represents an element 5a of the periodic table, and x represents a number 0 <x <1). ) It has been proposed to design a visible light responsive photocatalyst using a composite oxide semiconductor (Patent Document 2).
このような酸化チタン以外の複合酸化物によって光触媒を設計する試みは、本発明者等研究グループにおいて精力的、系統的に取り組んできた。すなわち、本発明者等において鋭意研究を重ねた結果、上記とは異なる複合酸化物によって紫外線は勿論、可視光領域の光に対しても活性を示す可視光応答型光触媒を設計することに成功し、その成果について一連の特許出願をした。 Attempts to design photocatalysts with such complex oxides other than titanium oxide have been vigorously and systematically conducted by the present inventors' research group. That is, as a result of intensive studies by the present inventors, the present inventors succeeded in designing a visible light responsive photocatalyst that exhibits activity not only for ultraviolet rays but also for light in the visible light region by using a complex oxide different from the above. A series of patent applications were filed for the results.
これを要約して列挙すると、以下(1)から(9)に記載するとおりである。
すなわち、その第1番目に開発に成功した可視光応答型光触媒は、(1)一般式;BVO4で表されるバナジウム(V)含有複合酸化物半導体(ただし、Bは周期律表中3b族
元素或いは3価の遷移金属を表す。)によって設計した光触媒が挙げられる(特許文献3)。
These are summarized and listed as described in (1) to (9) below.
That is, the first visible light responsive photocatalyst that has been successfully developed is (1) a general formula; a vanadium (V) -containing composite oxide semiconductor represented by BVO 4 (where B is a group 3b in the periodic table) (Represents an element or a trivalent transition metal)) (Patent Document 3).
次いで、その次に開発に成功した可視光応答型光触媒は、(2)一般式;RVO4で表
されるバナジウム(V)含有複合酸化物半導体(ただし、RはY元素或いはランタノイド元素を表す。)によって設計されてなる触媒である(特許文献4)。
Next, the visible light responsive photocatalyst that has been successfully developed next is (2) a general formula; a vanadium (V) -containing composite oxide semiconductor represented by RVO 4 (where R represents a Y element or a lanthanoid element). ) Is a catalyst designed by (Patent Document 4).
さらに、第3番目に開発に成功した可視光応答型光触媒は、(3)一般式;(BaO)n(In2O3)mで表される複合酸化物半導体(ただし、n=1から8、m=1から3)によって設計された(特許文献5)。 Furthermore, the visible light responsive photocatalyst that has been developed third is a composite oxide semiconductor represented by (3) general formula: (BaO) n (In 2 O 3 ) m (where n = 1 to 8). , M = 1 to 3) (Patent Document 5).
続いて第4番目に開発に成功した可視光応答型光触媒は、(4)一般式:ABO3(た
だし、式中、AはCa、Sr、Ba元素、BはB1とB2の2種類の元素がチャージバランスを取りながら置換したもので、そのうち、B1は、In、Co、Ni、Cu、Zn元素、B2はV、Nb、Ta、Cr、Mo、W元素を含む)で表される、ペロブスカイト型結晶構造を有する複合酸化物半導体によって設計されてなるものであり(特許文献6)、第5番目のものは、(5)一般式:MIn2O4で表されるインジウム系複合酸化物半導体(ただし、式中M=Ca,Sr,Baの中の少なくと1種の元素を表す)による可視光応答型光触媒であり(特許文献7)、さらに、第6番目は、(6)一般式:MBi2O4で表される複合酸化物半導体(ただし、M=Ca、Sr、Ba)からなる可視光応答型光触媒である(特許文献8)。
Subsequently, the fourth visible light responsive photocatalyst that has been successfully developed is (4) general formula: ABO 3 (where A is the Ca, Sr, Ba element, and B is the two elements B1 and B2). Perovskite, wherein B1 is an In, Co, Ni, Cu, Zn element, and B2 is a V, Nb, Ta, Cr, Mo, W element). Designed by a complex oxide semiconductor having a type crystal structure (Patent Document 6), the fifth one is (5) an indium complex oxide semiconductor represented by the general formula: MIn 2 O 4 (In the formula, M = Ca, Sr, Ba represents at least one element) Visible light responsive photocatalyst (Patent Document 7), and the sixth is (6) general formula : Composite oxide semiconductor represented by MBi 2 O 4 However, it is a visible light responsive photocatalyst composed of M = Ca, Sr, Ba) (Patent Document 8).
さらにまた、第7番目に開発された可視光応答型光触媒は、(7)一般式:MBiO3
・nH2Oで表される複合酸化物半導体(ただし、M=Li、Na、K、Ag、0≦n≦
2)によって設計されてなるものであり(特許文献9)、第8番目に開発されたものは、(8)一般式:AgxBiyMzOw(ただし、式中、MはV、Nb、Taの5A族金属元素から選ばれた1種または2種類以上の元素であり、0<x、y≦3、0<z≦9、0<w≦24の任意の数値)で表される複合酸化物半導体によって設計されてなるものであり(特許文献10)、続いて第9番目に開発された可視光応答型光触媒は、(9)一般式BaBixOy(式中、0.5<x<2、2.5<y<4)で表される複合酸化物半導体によって設計されてなるものである(特許文献11)。
Furthermore, the seventh developed visible light responsive photocatalyst is (7) General formula: MBiO 3
Complex oxide semiconductor represented by nH 2 O (where M = Li, Na, K, Ag, 0 ≦ n ≦
2) (Patent Document 9), and the eighth developed one is (8) General formula: Ag x Bi y M z O w (where M is V, One or more elements selected from the group 5A metal elements of Nb and Ta, represented by 0 <x, y ≦ 3, 0 <z ≦ 9, 0 <w ≦ 24, any numerical value) that composite oxides are those composed designed by semiconductor (Patent Document 10), followed by a visible-light-responsive photocatalyst developed ninth is (9) in the formula BaBi x O y (wherein, 0. It is designed by a composite oxide semiconductor represented by 5 <x <2, 2.5 <y <4) (Patent Document 11).
以上述べたように、近年、太陽光や室内照明に含まれているエネルギーの高い紫外光以外にも、これよりエネルギーの低い、波長の長い可視光領域の光に対して触媒活性を有する、光スペクトルを効率よく利用し得る光触媒、すなわち、紫外線、可視光線の両方に対しても高い活性を示す可視光応答型光触媒を希求する研究が活発に行われている。これによって、多様な光触媒を求めることが可能となり、選択の自由度も確保され、一応の成果が得られるようになってきたが、光を利用する反応に対して十分高い活性を有しているとは云えず、多様な環境に対しても適応し、高い活性を示す光触媒が求められている。 As described above, in addition to the high-energy ultraviolet light contained in sunlight and indoor lighting in recent years, light that has catalytic activity for light in the visible light region with a lower energy and longer wavelength than this. Research has been actively conducted to find a photocatalyst that can efficiently use the spectrum, that is, a visible light responsive photocatalyst exhibiting high activity for both ultraviolet rays and visible light. As a result, various photocatalysts can be obtained, the degree of freedom of selection is ensured, and a temporary result has been obtained, but it has a sufficiently high activity for reactions using light. However, there is a need for a photocatalyst that is adaptable to various environments and exhibits high activity.
とりわけ、触媒材料の設計上、容易に入手しえる酸化物によって調製され、酸化チタンやドープ型酸化チタン、あるいは前記提案による複合酸化物とも異なる組成によって構成され、その性能としてこれらの触媒活性と比較して遜色のない、あるいはこれを上回る触媒活性を有する可視光応答性光触媒が求められている。 In particular, it is prepared by oxides that are readily available in the design of catalyst materials, and is composed of a composition different from titanium oxide, doped titanium oxide, or the composite oxide proposed above, and its performance is compared with these catalytic activities. Therefore, a visible light responsive photocatalyst having a catalytic activity that is inferior or superior to that is required.
本発明は、このような要請に応えようというものである。さらには、光を照射することによって有害物質を酸化、還元、分解する、有害物質の無害化処理、あるいは汚れの清浄化さらには水素発生に供する光触媒材料とこの触媒を用いた有害物質の無害化処理方法、あるいは汚れ物質分解清浄化方法さらには水素発生方法を提供しようと云うものである。特に、最近では光触媒を汚れが付着しやすい表面にコーティングし、付着した汚れが光の作用によって分解するセルフクリーニング技術が注目されている。このようなセルフクリーニング技術に用いられる光触媒材料としては、良好な成膜性と環境に曝されても変質しない耐久性が要求されているが、本発明の汚れの清浄化に供せられる態様には、このようなセルフクリーニング技術による態様も含むものであり、この要請に対しても応えようというものである。 The present invention is intended to meet such a demand. Furthermore, it oxidizes, reduces, and decomposes harmful substances by irradiating light, detoxifies harmful substances, or cleans dirt, and also detoxifies harmful substances using this catalyst and photocatalyst materials used for hydrogen generation. The present invention intends to provide a treatment method, a method for decomposing and cleaning dirt substances, and a method for generating hydrogen. In particular, recently, a self-cleaning technique in which a photocatalyst is coated on a surface on which dirt easily adheres and the attached dirt is decomposed by the action of light has attracted attention. As a photocatalyst material used in such a self-cleaning technique, good film formability and durability that does not change even when exposed to the environment are required. This includes such a self-cleaning technique and is intended to meet this demand.
そのため本発明者等においては、前記した各種光触媒を前提従来技術として、これら従来技術の光触媒とは異なる組成の複合酸化物として、鉛、マグネシウム、ニオブを有する3元系酸化物について着目し鋭意研究を重ねた。その結果、これら3元系酸化物が特定の比率となったとき、可視光応答性の優れた光触媒能を発現しうることを見いだしたものである。その活性度は、酸化チタンよりも高く、また、ドープ型を利用した可視光応答型材料に見られるように、ドープによって再結合サイトが劇的に増え、これによって活性が十分に上昇しないということもなく、また成膜性にも優れ、表面に塗布され環境に曝されて
も、変質せず安定して優れた触媒効果を発現しうる材料であることを見いだしたものである。
本発明は、この知見に基づいてなされたものである。その構成は、以下、(1)〜(7)に記載するとおりである。
For this reason, the present inventors have made extensive studies focusing on ternary oxides containing lead, magnesium, and niobium as complex oxides having a composition different from those of the conventional photocatalysts based on the various photocatalysts described above. Repeated. As a result, it has been found that when these ternary oxides have a specific ratio, photocatalytic ability with excellent visible light response can be expressed. Its activity is higher than that of titanium oxide, and the recombination site increases dramatically by doping, as seen in the visible light responsive material using the doped type, and this does not increase the activity sufficiently. In addition, the present inventors have found that the material is excellent in film formability and can stably exhibit an excellent catalytic effect without being altered even when applied to the surface and exposed to the environment.
The present invention has been made based on this finding. The configuration is as described in (1) to (7) below.
(1)一般式;PbxMgyNbzOw(0<x≦3、0<y≦2、0<z≦3、0<w≦10)で表される組成を有する複合酸化物半導体からなることを特徴とする、可視光応答性光触媒。
(2)前記可視光応答性光触媒が、有害物質分解用に供されることを特徴とする、前項(1)に記載する可視光応答性光触媒。
(3)前記可視光応答性光触媒が、汚れを分解し、清浄化するのに供されることを特徴とする、前項(1)に記載する可視光応答性光触媒。
(4)前記可視光応答性光触媒が、水または水素含有物質を分解して水素を製造するのに供されることを特徴とする、前項(1)に記載する可視光応答性光触媒。
(5)一般式;PbxMgyNbzOw(0<x≦3、0<y≦2、0<z≦3、0<w≦10)で表される組成を有する複合酸化物半導体からなる可視光応答性光触媒を用い、この光触媒の存在下で有害物質に紫外線および可視光線を含む光を照射し、有害物質を分解することを特徴とした、有害物質分解除去方法。
(6)一般式;PbxMgyNbzOw(0<x≦3、0<y≦2、0<z≦3、0<w≦10)で表される組成を有する複合酸化物半導体からなる可視光応答性光触媒を用い、この光触媒の存在下で汚れ物質に紫外線および可視光線を含む光を照射し、汚れ物質を分解することを特徴とした、汚れ物質分解清浄化方法。
(7)一般式;PbxMgyNbzOw(0<x≦3、0<y≦2、0<z≦3、0<w≦10)で表される組成を有する複合酸化物半導体からなる可視光応答性光触媒を用い、この光触媒の存在下で水または水素含有物質に紫外線および可視光線を含む光を照射し、水または水素含有物質を分解して水素を発生することを特徴とした、水素発生方法。
(1) A composite oxide semiconductor having a composition represented by the general formula: Pb x Mg y Nb z O w (0 <x ≦ 3, 0 <y ≦ 2, 0 <z ≦ 3, 0 <w ≦ 10) A visible light responsive photocatalyst characterized by comprising:
(2) The visible light responsive photocatalyst described in (1) above, wherein the visible light responsive photocatalyst is used for decomposing harmful substances.
(3) The visible light responsive photocatalyst described in (1) above, wherein the visible light responsive photocatalyst is used for decomposing and cleaning dirt.
(4) The visible light responsive photocatalyst described in (1) above, wherein the visible light responsive photocatalyst is used to produce water by decomposing water or a hydrogen-containing substance.
(5) A composite oxide semiconductor having a composition represented by the general formula: Pb x Mg y Nb z O w (0 <x ≦ 3, 0 <y ≦ 2, 0 <z ≦ 3, 0 <w ≦ 10) A method for decomposing and removing harmful substances, comprising using a visible light responsive photocatalyst comprising: irradiating a harmful substance with light containing ultraviolet rays and visible light in the presence of the photocatalyst to decompose the harmful substance.
(6) A composite oxide semiconductor having a composition represented by the general formula: Pb x Mg y Nb z O w (0 <x ≦ 3, 0 <y ≦ 2, 0 <z ≦ 3, 0 <w ≦ 10) A method for decomposing and cleaning a dirt substance, comprising using a visible light responsive photocatalyst comprising: irradiating a dirt substance with light containing ultraviolet rays and visible light in the presence of the photocatalyst to decompose the dirt substance.
(7) A composite oxide semiconductor having a composition represented by the general formula: Pb x Mg y Nb z O w (0 <x ≦ 3, 0 <y ≦ 2, 0 <z ≦ 3, 0 <w ≦ 10) It is characterized by using a visible light responsive photocatalyst comprising, irradiating water or a hydrogen-containing substance with light containing ultraviolet rays and visible light in the presence of the photocatalyst, and decomposing the water or hydrogen-containing substance to generate hydrogen. Hydrogen generation method.
本発明は、鉛とニオブとマグネシウムからなり、これらの比率が極めて広範な領域に亘る複合酸化物半導体からなる光触媒であって、光を照射すると可視光領域の波長のスペクトルを十分に吸収することができ、これまで実用化されてきた酸化チタンをベースとした紫外光応答型光触媒に比して、極めて優位性を持つ材料である。また、CrやNをドープした材料に比べても、欠陥量が少なく、電子とホールの再結合も起こりづらく、光触媒活性も高い。本発明によれば、紫外光のみならず、可視光を利用して工場などで最もよく利用されているVOCの1種、2−プロピルアルコール(IPA)を効率よく分解できる格別の効果を有してなるものである。この光触媒の特性はこれだけにとどまらず、光を照射することによってその他の有害ガス、たとえば、シックハウス症候群の原因ガスの1つであるアルデヒドガスや環境ホルモンなどの様々な有害物質を分解、除去することができる能力を有している。本発明の複合酸化物半導体光触媒は、可視光、紫外光領域に対して活性を有することは上記の通りであり、その特性の故、前示した使用例以外にも多様な用途に利用できることが期待され、今後その果たす役割は、非常に大きいものと考えられる。さらにまた、その触媒性能は、前述した複合酸化物による可視光応答性光触媒に比しても、本発明の光触媒能は優るとも劣ることはない。 The present invention is a photocatalyst composed of a complex oxide semiconductor composed of lead, niobium and magnesium, and the ratio of these is very wide, and sufficiently absorbs the spectrum of the wavelength in the visible light region when irradiated with light. Therefore, it is a material that has a significant advantage over the titanium oxide-based ultraviolet light-responsive photocatalyst that has been put into practical use. Also, compared to materials doped with Cr or N, the amount of defects is small, recombination of electrons and holes hardly occurs, and photocatalytic activity is high. According to the present invention, not only ultraviolet light but also visible light can be used to effectively decompose one type of VOC, 2-propyl alcohol (IPA), which is most often used in factories and the like. It will be. This photocatalyst is not limited to this, but it also decomposes and removes other harmful gases, such as aldehyde gas and environmental hormones, which are one of the cause gases of sick house syndrome, by irradiating light. Has the ability to As described above, the composite oxide semiconductor photocatalyst of the present invention has activity in the visible light and ultraviolet light regions, and because of its characteristics, it can be used in various applications other than the use examples shown above. Expected and expected to play a very important role in the future. Furthermore, the catalyst performance of the present invention is not inferior to the photocatalytic ability of the present invention as compared with the visible light responsive photocatalyst using the composite oxide described above.
本発明の光触媒としての複合酸化物半導体を得るためには、通常の固相反応法、すなわち原料となる各金属成分の酸化物あるいは金属炭酸塩あるいは金属硝酸塩あるいは金属硫酸塩、あるいは金属塩化物を目的組成の比率で混合し、常圧下空気中で焼成することによって合成することができる。 In order to obtain a composite oxide semiconductor as a photocatalyst of the present invention, an ordinary solid phase reaction method, that is, an oxide, metal carbonate, metal nitrate, metal sulfate, or metal chloride of each metal component as a raw material is used. It can synthesize | combine by mixing by the ratio of the target composition and baking in air under a normal pressure.
この触媒を構成するPb、Mg、Nbの各成分の比率x、y、zは、x:y:z=0を超え3以下:0を超え2以下:0を超え3以下、であればよく、各成分のモル比は極めて広い範囲において有効である。焼成の際、原料成分によっては、昇華し、触媒の材料設計に、計画された設計とはズレが生ずることもあるが、この場合、昇華に見合う量を最初から多めに加えておくことによって対処することができる。 The ratio x, y, z of each component of Pb, Mg, and Nb constituting this catalyst may be x: y: z = 0 to 3 or less: 0 to 2 or less: 0 to 3 or less. The molar ratio of each component is effective in a very wide range. Depending on the raw material components during firing, the material design of the catalyst may deviate from the planned design. In this case, add a suitable amount for sublimation from the beginning. can do.
また、上記原料以外に金属アルコキシドや金属塩を原料とし、これをいわゆるゾルゲル法、共沈法、錯体重合法、スパッタリング法、化学蒸着法、水熱合成法などといった様々な方法によって調製することができ、何れの調製プロセスによっても実施可能である。調整された配合原料を焼成する際の焼成温度は、原料物質が分解して酸化物に転換され、酸化物からなる焼結体が得られる温度であればよい。具体的には、700℃以上1500℃以下の温度範囲でよく、好ましくは、850℃以上、1050℃以下である。 In addition to the above raw materials, a metal alkoxide or a metal salt is used as a raw material, which can be prepared by various methods such as so-called sol-gel method, coprecipitation method, complex polymerization method, sputtering method, chemical vapor deposition method, hydrothermal synthesis method and the like. It can be carried out by any preparation process. The firing temperature at which the adjusted blended raw material is fired may be any temperature at which the raw material is decomposed and converted into an oxide to obtain a sintered body made of the oxide. Specifically, the temperature range may be 700 ° C. or more and 1500 ° C. or less, and preferably 850 ° C. or more and 1050 ° C. or less.
触媒を調製する際の原料調整は、一般式:PbxMgyNbzOw(0<x≦3、0<y≦2、0<z≦3、0<w≦10)に基づいて決定される。この一般式を満足するよう原料配合し、焼成することによって調製される。この一般式の意味、意義は、鉛、マグネシウム、ニオブがそれぞれ規定量を満足して限り光触媒として機能するものが得られるものであるが、その一部を他の元素によって置換し含んでいても可視光応答性を示すことができ、本発明は、このような態様も含み得、排除するものでない。 The raw material adjustment in preparing the catalyst is determined based on the general formula: Pb x Mg y Nb z O w (0 <x ≦ 3, 0 <y ≦ 2, 0 <z ≦ 3, 0 <w ≦ 10) Is done. It is prepared by blending the raw materials so as to satisfy this general formula and firing. The meaning and meaning of this general formula are those that can function as a photocatalyst as long as lead, magnesium, and niobium satisfy the specified amounts, respectively, but some of them may be substituted with other elements. Visible light responsiveness can be shown, and the present invention can include such an embodiment and is not excluded.
具体的にはPbやMgの一部をその他の2価の金属元素で置き換えてもよいし、Nbの一部をその他の5価の金属元素で置き換えても可視光応答型光触媒として用いることができる。これら他の成分の混入・置換については、一義的に規定することができない。すなわち、これら他の成分の混入・置換によって光触媒が向上する場合、これら他の成分の混入・置換はむしろ好ましいといえ、特に排除する必要はない。しかしながら、その成分が、混入、置換されたことによって、光触媒効果が希釈されるような場合、触媒効果の低下を防ぐため極力混入しないよう配慮することが好ましい。 Specifically, a part of Pb or Mg may be replaced with another divalent metal element, or even if a part of Nb is replaced with another pentavalent metal element, it can be used as a visible light responsive photocatalyst. it can. The mixing / substitution of these other components cannot be uniquely defined. That is, when the photocatalyst is improved by mixing / substitution of these other components, it can be said that mixing / substitution of these other components is rather preferable and does not need to be excluded. However, when the photocatalytic effect is diluted by mixing and replacing the component, it is preferable to consider not mixing as much as possible in order to prevent a decrease in the catalytic effect.
本発明の光触媒の形状、粒径は、光を有効に利用するためにできるだけ表面積が大きくなるように設計されることが望ましい。固相反応法によって作製した複合酸化物光触媒は、大きな成型物あるいは塊状物として得られるため、これをボールミルなどで粉砕するか、あるいは酸などでエッチングすることによってさらに表面積を大きくすることができる。また、メソポーラス構造になるように合成して、表面積を大きくしてもよい。さらに、粉末粒子を適宜大きさの形状、形態に成形して使用することもできる。本発明の光触媒は、焼結法以外にも、前述記載した様々な調整手段が利用でき、たとえば、触媒成分を含む水溶液等の反応原料溶液を用意し、反応溶液から共析反応、あるいは共沈反応によって、触媒成分を含む物質を共析、共沈させ、それらをさらに乾燥脱水あるいは焼成することによっても作製することができる。 The shape and particle size of the photocatalyst of the present invention are desirably designed so that the surface area becomes as large as possible in order to effectively use light. Since the composite oxide photocatalyst produced by the solid phase reaction method is obtained as a large molded product or a lump, the surface area can be further increased by pulverizing it with a ball mill or etching with an acid or the like. Further, the surface area may be increased by synthesizing so as to have a mesoporous structure. Furthermore, it is possible to use the powder particles by appropriately shaping them into a shape and shape. The photocatalyst of the present invention can use the various adjusting means described above in addition to the sintering method. For example, a reaction raw material solution such as an aqueous solution containing a catalyst component is prepared, and a eutectoid reaction or coprecipitation is performed from the reaction solution. It can also be produced by co-depositing and co-precipitating a substance containing a catalyst component by reaction and further drying or dehydrating or calcining them.
本発明の光触媒材料の光触媒反応により分解あるいは酸化あるいは還元反応により除去できる有害物質としては環境ホルモン、農薬、殺虫剤、カビ、細菌、ウィルス、藻類、環境汚染物質、フロンガス、炭化水素、アルコール、アルデヒド、ケトン、カルボン酸、一酸化炭素、アミン、油、芳香族化合物、有機ハロゲン化合物、窒素化合物、硫黄化合物、有機リン化合物、蛋白質などが挙げられる。さらに身の回りの汚れの原因となっている石鹸や油、手垢、茶渋、台所のシンクなどのぬめりなどもこの光触媒材料の光触媒反応により分解できる。 Hazardous substances that can be decomposed or removed by oxidation or reduction reaction of the photocatalytic material of the present invention include environmental hormones, agricultural chemicals, insecticides, molds, bacteria, viruses, algae, environmental pollutants, chlorofluorocarbons, hydrocarbons, alcohols, aldehydes , Ketone, carboxylic acid, carbon monoxide, amine, oil, aromatic compound, organic halogen compound, nitrogen compound, sulfur compound, organic phosphorus compound, protein and the like. In addition, soap and oil, hand stains, tea astringents, and slimes such as kitchen sinks that cause personal contamination can be decomposed by the photocatalytic reaction of this photocatalytic material.
以下、本発明を具体的な実施例と図面に基づいて詳細に説明するが、これらは本発明を限定するものではない。以下に記載する実施例においては、一般式:PbxMgyNbzOw
(0<x≦3、0<y≦2、0<z≦3、0<w≦10)で示される複合酸化物半導体光触媒として、x、y、z、wの値が特定の値である、Pb1.83Mg0.29Nb1.71O6.39を実施例として開示し、これを固相反応法によって合成した場合の実施例である。ただし、繰り返すがこの実施例は、あくまでも本発明を具体的に説明するための一つの実施例であって、本発明は、この実施例によって限定されるものでない。
Hereinafter, although the present invention is explained in detail based on a concrete example and a drawing, these do not limit the present invention. In the examples described below, the general formula: Pb x Mg y Nb z O w
As the composite oxide semiconductor photocatalyst represented by (0 <x ≦ 3, 0 <y ≦ 2, 0 <z ≦ 3, 0 <w ≦ 10), the values of x, y, z, and w are specific values. , Pb 1.83 Mg 0.29 Nb 1.71 O 6.39 is disclosed as an example, and this is an example when synthesized by a solid phase reaction method. However, although it repeats, this Example is one Example for demonstrating this invention to the last, Comprising: This invention is not limited by this Example.
実施例1;
鉛、ニオブ、マグネシウムからなる複合酸化物半導体の1つであるPb1.83Mg0.29Nb1.71O6.39を以下に述べるように固相反応法によって合成した。
先ず、酸化鉛を3.0gと水酸化炭酸マグネシウムを0.21g、酸化ニオブを1.8gそれぞれ秤量した。これらをボールミルや乳鉢などの粉砕混合器具を利用して十分に粉砕混合したあと、アルミナるつぼに入れて、大気圧空気雰囲気下で950℃にて5時間焼結し、粉末を得た。この粉末をX線回折装置を用いて、測定したところ、目的のPb1.83Mg0.29Nb1.71O6.39の単相のパイロクロア構造をとる物質が得られていることがわかった(図1)。
紫外−可視吸収スペクトル測定の結果、本実施例の光触媒は紫外線領域から約450nm程度までの可視光領域まで吸収を示し、バンドキャップは2.8eV程度と見積もることができた(図2)。
Example 1;
Pb 1.83 Mg 0.29 Nb 1.71 O 6.39 , which is one of complex oxide semiconductors composed of lead, niobium and magnesium, was synthesized by a solid phase reaction method as described below.
First, 3.0 g of lead oxide, 0.21 g of magnesium hydroxide carbonate, and 1.8 g of niobium oxide were weighed. These were sufficiently pulverized and mixed using a pulverizing and mixing device such as a ball mill and a mortar, then placed in an alumina crucible and sintered at 950 ° C. for 5 hours in an atmospheric air atmosphere to obtain a powder. When this powder was measured using an X-ray diffractometer, it was found that a substance having a single-phase pyrochlore structure of the target Pb 1.83 Mg 0.29 Nb 1.71 O 6.39 was obtained (FIG. 1).
As a result of ultraviolet-visible absorption spectrum measurement, the photocatalyst of this example showed absorption from the ultraviolet region to the visible light region of about 450 nm, and the band cap could be estimated to be about 2.8 eV (FIG. 2).
実施例2;
実施例1で得られた0.4gのPb1.83Mg0.29Nb1.71O6.39で約250ppmの2−プロピルアルコールの分解試験を行った。光源には300W Xeランプを用い、カットオフフィルターを利用して、420nmから520nmの可視光(光量:0.9mWcm-2)を反応容器に照射した。2−プロピルアルコールとその分解物質のアセトン、二酸化炭素の検出及び定量はメタナイザー付ガスクロマトグラフィー(検出器はFID)で行い、2−プロピルアルコールを分解したときに生成する中間体アセトンの発生量の時間変化について調べた(図3)。その結果、1時間で約80ppmものアセトンが生成し、この材料は可視光応答型の光触媒であることが明らかになった。また、さらに長時間光照射すると、二酸化炭素にまで完全に酸化分解することも明らかになった。
Example 2;
A decomposition test of about 250 ppm of 2-propyl alcohol was conducted with 0.4 g of Pb 1.83 Mg 0.29 Nb 1.71 O 6.39 obtained in Example 1. A 300 W Xe lamp was used as the light source, and visible light (light quantity: 0.9 mWcm −2 ) of 420 nm to 520 nm was irradiated to the reaction vessel using a cutoff filter. Detection and quantification of 2-propyl alcohol and its decomposition substances acetone and carbon dioxide are performed by gas chromatography with a methanizer (detector is FID), and the amount of intermediate acetone generated when 2-propyl alcohol is decomposed is measured. The change with time was examined (FIG. 3). As a result, about 80 ppm of acetone was produced in one hour, and it was revealed that this material is a visible light responsive photocatalyst. It was also revealed that when light was irradiated for a longer time, it was completely oxidatively decomposed to carbon dioxide.
実施例3;
実施例1で得られた0.5gのPb1.83Mg0.29Nb1.71O6.39を用いて、メタノール水溶液からの水素生成実験を行った。カットオフフィルターとキセノンランプを利用して、400nm以上の可視光を光源として、利用した。その結果、約5時間で約40μmolの
水素の生成が確認された。
Example 3;
Using 0.5 g of Pb 1.83 Mg 0.29 Nb 1.71 O 6.39 obtained in Example 1, a hydrogen generation experiment from an aqueous methanol solution was performed. Using a cut-off filter and a xenon lamp, visible light of 400 nm or more was used as a light source. As a result, it was confirmed that about 40 μmol of hydrogen was produced in about 5 hours.
比較例1;
代表的な光触媒であるTiO2を利用して2−プロピルアルコール分解の可視光分解活
性を調べた。測定に使用した機器は実施例2と同じであった。その結果、
1時間経過してもアセトン、二酸化炭素の生成量はなく、気相中の2−プロピルアルコールの量に変化もないことから2−プロピルアルコールは、全く分解されないことが確認された(図3)。紫外光において優れた活性を示すTiO2も可視光照射においては活性を
示さず、可視光領域における光触媒活性は鉛とニオブとマグネシウムからなる複合酸化物半導体よりも著しく劣っていた。以上のことから、このTiO2光触媒は、可視光照射下
においては2−プロピルアルコールをはじめとする有機物を分解する能力がないことが再確認された。
Comparative Example 1;
The visible light decomposition activity of 2-propyl alcohol decomposition was investigated using TiO 2 which is a typical photocatalyst. The equipment used for the measurement was the same as in Example 2. as a result,
Even if 1 hour passed, there was no production amount of acetone and carbon dioxide, and since there was no change in the amount of 2-propyl alcohol in the gas phase, it was confirmed that 2-propyl alcohol was not decomposed at all (FIG. 3). . TiO 2 exhibiting excellent activity in ultraviolet light also showed no activity in visible light irradiation, and its photocatalytic activity in the visible light region was significantly inferior to a composite oxide semiconductor composed of lead, niobium and magnesium. From the above, it was reconfirmed that this TiO 2 photocatalyst has no ability to decompose organic substances such as 2-propyl alcohol under irradiation with visible light.
比較例2;
代表的な可視光応答型光触媒である窒素ドープ型TiO2を利用して2−プロピルアル
コールの可視光分解活性を調べた。試料の作製方法は後述する非特許文献3に記載の要領
に基づいて合成した。測定に使用した機器は実施例2と同じであった。その結果、1時間でアセトンが約20ppm生成することが確認され、実施例2と比較した場合、光触媒活性は約4倍劣っていることがわかった(図3)。また、比表面積を比較したところ、比較例2、実施例2の比表面積はそれぞれ、約43m2g-1、約1.7m2g-1と約20倍以上、比較例2のほうが大きかった。そのほかの性質が同じならば、一般的に比表面積が大きな材料ほど活性が高くなることが知られており、もし、実施例2と比較例2が同じ比表面積ならば、その活性の差は数十倍実施例2のほうが高くなることが予想される。このように鉛、ニオブ、マグネシウムからなる複合酸化物半導体は既存の可視光応答型材料よりも高い活性を持っており、非常に有効な可視光応答型の光触媒材料であることがわかる。
Comparative Example 2;
The visible light decomposition activity of 2-propyl alcohol was examined using nitrogen-doped TiO 2 which is a typical visible light responsive photocatalyst. The sample preparation method was synthesized based on the procedure described in Non-Patent Document 3 described later. The equipment used for the measurement was the same as in Example 2. As a result, it was confirmed that about 20 ppm of acetone was produced in 1 hour, and it was found that the photocatalytic activity was about 4 times inferior when compared with Example 2 (FIG. 3). In addition, when comparing the specific surface area, Comparative Example 2, respectively the specific surface area of Example 2, about 43m 2 g -1, about 1.7 m 2 g -1 and about 20 times or more, it was greater towards the Comparative Example 2 . If other properties are the same, it is generally known that a material having a larger specific surface area has higher activity. If Example 2 and Comparative Example 2 have the same specific surface area, the difference in activity is several. Ten times Example 2 is expected to be higher. Thus, it can be seen that the complex oxide semiconductor composed of lead, niobium, and magnesium has a higher activity than existing visible light responsive materials, and is a very effective visible light responsive photocatalytic material.
以上の結果について、図1−3に示していることは、前述したとおりである。また、上記実施例以外にもぺロブスカイト構造を持つPb3MgNb2O9などは可視光に吸収を示
し、可視光照射下で有機物を効率よく分解する。
すなわち、鉛、ニオブ、マグネシウムからなる複合酸化物半導体は高活性な可視光応答型光触媒材料であり、前述の目的に沿う材料の開発に成功したことを示している。これによって、照射される光の波長に対して、利用効率が高まり、光触媒反応に一層有効に利用され、寄与するものと期待される。
About the above result, it has shown to FIGS. 1-3 as above-mentioned. In addition to the above examples, Pb 3 MgNb 2 O 9 having a perovskite structure absorbs visible light and efficiently decomposes organic substances under irradiation with visible light.
That is, a complex oxide semiconductor composed of lead, niobium, and magnesium is a highly active visible light responsive photocatalytic material, indicating that the material that meets the above-mentioned purpose has been successfully developed. As a result, the use efficiency is increased with respect to the wavelength of the irradiated light, and it is expected to be more effectively utilized and contribute to the photocatalytic reaction.
以上説明してきたように、本発明は、PbxMgyNbzOw(0<x≦3、0<y≦2、0<z≦3、0<w≦10)複合酸化物半導体光触媒は、紫外光のみならず、十分に可視光まで吸収できる。本発明によって、これまでの実用光触媒、TiO2が、紫外光領域で
のみ機能していたことを考えると、有効利用できる波長領域を大きく広げることができたという意義は極めて大きい。また、可視光領域においても既存の窒素ドープ型酸化チタンよりもはるかに活性が高い。本発明によれば、可視光を利用して各種有害な化合物、例えば、環境ホルモンや細菌等いわゆる有害物質に作用し、これらを殺菌、分解、除去等無害化するのに使用される環境対策技術を始めとして各種化学反応に大いに利用され、産業の発展に寄与するものと期待される。
As described above, the present invention provides a Pb x Mg y Nb z O w (0 <x ≦ 3, 0 <y ≦ 2, 0 <z ≦ 3, 0 <w ≦ 10) composite oxide semiconductor photocatalyst. It can absorb not only ultraviolet light but also visible light. Considering that the present practical photocatalyst, TiO 2, has functioned only in the ultraviolet light region according to the present invention, it is extremely significant that the wavelength region that can be effectively used can be greatly expanded. In the visible light region, the activity is much higher than that of the existing nitrogen-doped titanium oxide. According to the present invention, environmental countermeasure technology used to make various harmful compounds using visible light, such as environmental hormones and bacteria, so-called harmful substances, sterilize, decompose, remove, etc. It is expected to contribute to the development of industry by being used for various chemical reactions.
Claims (7)
Visible compound oxide semiconductor having a composition represented by the general formula: Pb x Mg y Nb z O w (0 <x ≦ 3, 0 <y ≦ 2, 0 <z ≦ 3, 0 <w ≦ 10) Hydrogen, characterized by using a photoresponsive photocatalyst and irradiating water or a hydrogen-containing substance with light containing ultraviolet rays and visible light in the presence of the photocatalyst to decompose water or the hydrogen-containing substance to generate hydrogen. How it occurs.
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JPS6274452A (en) * | 1985-09-27 | 1987-04-06 | Nippon Kogaku Kk <Nikon> | Photolytic catalyst of water |
JPH01276506A (en) * | 1988-04-28 | 1989-11-07 | Tdk Corp | High permitivity ceramic composition |
JPH02172535A (en) * | 1988-12-26 | 1990-07-04 | Nikon Corp | New photolysis catalyst for water |
JPH03193626A (en) * | 1989-12-21 | 1991-08-23 | Shinichi Hirano | Production of perovskite type oxide |
JP2001232191A (en) * | 2000-02-25 | 2001-08-28 | Japan Science & Technology Corp | Photocatalyst having improved activity and activity persistence |
JP2001286766A (en) * | 2000-04-11 | 2001-10-16 | Nippon Soda Co Ltd | Photocatalyst-bearing structure body, production method of the same, composition for intermediate layer |
JP2003171578A (en) * | 2001-12-06 | 2003-06-20 | Sumitomo Chem Co Ltd | Coating liquid and photocatalyst functional product |
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JPS6274452A (en) * | 1985-09-27 | 1987-04-06 | Nippon Kogaku Kk <Nikon> | Photolytic catalyst of water |
JPH01276506A (en) * | 1988-04-28 | 1989-11-07 | Tdk Corp | High permitivity ceramic composition |
JPH02172535A (en) * | 1988-12-26 | 1990-07-04 | Nikon Corp | New photolysis catalyst for water |
JPH03193626A (en) * | 1989-12-21 | 1991-08-23 | Shinichi Hirano | Production of perovskite type oxide |
JP2001232191A (en) * | 2000-02-25 | 2001-08-28 | Japan Science & Technology Corp | Photocatalyst having improved activity and activity persistence |
JP2001286766A (en) * | 2000-04-11 | 2001-10-16 | Nippon Soda Co Ltd | Photocatalyst-bearing structure body, production method of the same, composition for intermediate layer |
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