JP3887510B2 - Photocatalyst film and method for producing the same - Google Patents
Photocatalyst film and method for producing the same Download PDFInfo
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- JP3887510B2 JP3887510B2 JP21305299A JP21305299A JP3887510B2 JP 3887510 B2 JP3887510 B2 JP 3887510B2 JP 21305299 A JP21305299 A JP 21305299A JP 21305299 A JP21305299 A JP 21305299A JP 3887510 B2 JP3887510 B2 JP 3887510B2
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- film
- tungsten oxide
- ruthenium
- photocatalyst
- oxide film
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- 239000011941 photocatalyst Substances 0.000 title claims description 39
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 claims description 72
- 229910001930 tungsten oxide Inorganic materials 0.000 claims description 72
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 44
- 239000000758 substrate Substances 0.000 claims description 24
- 230000015572 biosynthetic process Effects 0.000 claims description 20
- 238000007740 vapor deposition Methods 0.000 claims description 14
- 230000001699 photocatalysis Effects 0.000 claims description 13
- 229910052697 platinum Inorganic materials 0.000 claims description 13
- 229910052707 ruthenium Inorganic materials 0.000 claims description 13
- 229910001925 ruthenium oxide Inorganic materials 0.000 claims description 13
- WOCIAKWEIIZHES-UHFFFAOYSA-N ruthenium(iv) oxide Chemical compound O=[Ru]=O WOCIAKWEIIZHES-UHFFFAOYSA-N 0.000 claims description 13
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 claims description 12
- 238000004544 sputter deposition Methods 0.000 claims description 12
- 238000010894 electron beam technology Methods 0.000 claims description 11
- 230000005284 excitation Effects 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 5
- 238000003980 solgel method Methods 0.000 claims description 4
- 238000005229 chemical vapour deposition Methods 0.000 claims description 3
- 238000001704 evaporation Methods 0.000 claims description 3
- 230000001678 irradiating effect Effects 0.000 claims description 3
- 150000002500 ions Chemical class 0.000 claims description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 35
- 230000000694 effects Effects 0.000 description 26
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 description 20
- 238000000034 method Methods 0.000 description 20
- 230000000052 comparative effect Effects 0.000 description 15
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical group O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 13
- 238000000354 decomposition reaction Methods 0.000 description 13
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 12
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 12
- 229910052751 metal Inorganic materials 0.000 description 10
- 239000002184 metal Substances 0.000 description 10
- 239000011230 binding agent Substances 0.000 description 9
- 230000007423 decrease Effects 0.000 description 9
- 239000007789 gas Substances 0.000 description 9
- 239000001301 oxygen Substances 0.000 description 9
- 229910052760 oxygen Inorganic materials 0.000 description 9
- 229910052788 barium Inorganic materials 0.000 description 8
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 8
- 230000003197 catalytic effect Effects 0.000 description 8
- 239000011521 glass Substances 0.000 description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- 229910052786 argon Inorganic materials 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 239000003513 alkali Substances 0.000 description 5
- 239000006227 byproduct Substances 0.000 description 5
- 239000003054 catalyst Substances 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- IKHGUXGNUITLKF-XPULMUKRSA-N acetaldehyde Chemical compound [14CH]([14CH3])=O IKHGUXGNUITLKF-XPULMUKRSA-N 0.000 description 4
- 238000000151 deposition Methods 0.000 description 4
- 230000008021 deposition Effects 0.000 description 4
- 238000011068 loading method Methods 0.000 description 4
- 238000000746 purification Methods 0.000 description 4
- 239000013078 crystal Substances 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229910010413 TiO 2 Inorganic materials 0.000 description 2
- 230000000844 anti-bacterial effect Effects 0.000 description 2
- UHYPYGJEEGLRJD-UHFFFAOYSA-N cadmium(2+);selenium(2-) Chemical compound [Se-2].[Cd+2] UHYPYGJEEGLRJD-UHFFFAOYSA-N 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 238000005468 ion implantation Methods 0.000 description 2
- 238000001755 magnetron sputter deposition Methods 0.000 description 2
- 239000005416 organic matter Substances 0.000 description 2
- 230000001443 photoexcitation Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 2
- 239000013077 target material Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 241000208125 Nicotiana Species 0.000 description 1
- 235000002637 Nicotiana tabacum Nutrition 0.000 description 1
- 229910019899 RuO Inorganic materials 0.000 description 1
- 230000032900 absorption of visible light Effects 0.000 description 1
- 125000000218 acetic acid group Chemical class C(C)(=O)* 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000003373 anti-fouling effect Effects 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 230000002301 combined effect Effects 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 230000002070 germicidal effect Effects 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- -1 oxygen ions Chemical class 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 238000002256 photodeposition Methods 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
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- 239000004065 semiconductor Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 238000009751 slip forming Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000011882 ultra-fine particle Substances 0.000 description 1
Landscapes
- Catalysts (AREA)
- Physical Vapour Deposition (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は光触媒膜、特に可視光領域でも触媒活性を発現できる光触媒膜に関する。
【０００２】
【従来の技術】
光触媒にそのバンドギャップ以上のエネルギーを持つ波長の光を照射すると光励起により伝導帯に電子を、価電子帯に正孔を生じる。この光励起により生じた電子の持つ強い還元力や正孔の持つ強い酸化力は、有機物の分解・浄化、水の分解、窒素酸化物の除去、二酸化炭素の分解・固定化などへ利用が検討されており、抗菌・浄化の分野では一部で実用化が進められている。
【０００３】
光触媒として最も代表的な材料は酸化チタンである。酸化チタンは高活性であると同時に化学的な安定性に優れ、光触媒としての活性は半永久的に持続する。また、人体に無害に無害であって、資源として豊富、安価という特長を有する。しかし、ｎ型半導体の一種である酸化チタンを触媒として活性化させるためには、大きな活性が得られるアナターゼ結晶の場合、バンドギャップは約３．２ｅＶであり、３８０ｎｍ以下の紫外光を照射する必要が有る。したがって、例えば、酸化チタン光触媒を用いた空気清浄機は、空気中のタバコ等による臭気成分を脱臭するために、紫外光を照射するブラックライトや殺菌灯が組み込まれている。酸化チタンに白色蛍光灯、昼光色蛍光灯、太陽光等の自然光を照射しても、微量の紫外線によって僅かながら活性を得ることが可能で、抗菌・防汚の分野で徐々に検討が進み、ＮＯX の浄化検討も進められている。しかし活性が小さく、エネルギ−効率が悪いという欠点がある。
【０００４】
このような欠点を解消し、酸化チタンの可視光での光触媒活性を得るため、例えば、酸化チタンヘ各種材料をドーピングする検討が行われ、近年、イオン注入法によるドーピングが注目されている（特開平９−２６２４８２号公報等）。しかし、ドーピングを行うと可視光の吸収は得られるが、一般的にいって触媒活性が低下する問題があり、イオン注入法を用いると触媒活性の低下は改善されるものの大きな面積の基板を連続的に処理するのが困難で、量産性に乏しいという問題がある。
【０００５】
酸化チタンの上記問題を解決するため、酸化チタン以外に可視光を吸収する材料として、Ｆｅ2 Ｏ3 、ＣｄＳ、ＣｄＳｅ、ＧａＰ等が検討されてきた。しかし、Ｆｅ2 Ｏ3 は活性がほとんど得られず、ＣｄＳ、ＣｄＳｅ、ＧａＰは初期的に活性が得られても安定性が悪いため、活性の低下・水への溶解の問題がある。
【０００６】
また、ＷＯ3 も可視光での活性は得られることが知られているが、一般に安定性が悪く信頼性に問題があると言われている。さらに、発明者らの検討の結果、酸化タングステン光触媒は特定の成分に対する分解活性が極端に小さく、かつ、副生成物を生じ易く、その副生成物が酸化タングステン膜表面に吸着され、活性が大きく低下するという問題が有る。例えば、代表的な臭気成分の１つであるアセトアルデヒドを酸化タングステン光触媒で分解する場合、副生成物として多量の酢酸が生成する。この酢酸が酸化タングステン表面に吸着し、しかも、酢酸の分解速度が極めて遅いため、光触媒活性が大きく低下する。
【０００７】
【発明が解決しようとする課題】
そこで、本発明は、光吸収帯を可視光領域までシフトして触媒活性を発現し、しかもその活性が特定物質によって低下させられることなく、安定的に維持される光触媒を提供することを目的とする。
【０００８】
【課題を解決するための手段】
かかる目的達成するため、酸化タングステンに着目し、酸化タングステン膜の構成やこれと金属の組み合わせについて鋭意研究した結果、バインダ−を用いない酸化タングステン膜に白金、ルテニウム、酸化ルテニウムの１種又は２種以上を担持した光触媒膜が、紫外光領域可視光領域の光を吸収して安定した触媒活性を示すことを見出だし、本発明を完成させた。
【０００９】
すなわち、本発明のうち請求項１に記載の発明は、酸化タングステンのみから構成される酸化タングステン膜に、白金、ルテニウム、酸化ルテニウムの１種又は２種以上を担持した光触媒膜であって、担持された白金、ルテニウム、酸化ルテニウムの１種又は２種以上の体積が、酸化タングステン膜表面１ｃｍ2 当たり５×１０-9ｃｍ3 以上、３×１０-7ｃｍ3 以下であることを特徴とする光触媒膜である。
【００１０】
ここで、「酸化タングステンのみから構成される酸化タングステン膜」とは、バインダ−を用いない酸化タングステンのみで構成した膜の意味である。このように構成された酸化タングステン膜は、第１に光触媒を粉末状態で使用する場合に比較すると、粉末触媒が、触媒による浄化等を行つた後、触媒粉末のみを反応系から分離回収する必要があるがのに対しその必要がなく、第２に、タングステン粒子をシリカ、アルミナ等のバインダ−を用いて形成した膜に比較すると、この様な膜が可視光を吸収して触媒活性が発現しても活性がほとんど消失してしまうのに対し、そのような問題が発生せず酸化タングステン本来の活性を得ることができる。
【００１１】
また、酸化タングステン膜表面に白金、ルテニウム、酸化ルテニウムの１種又は２種以上を担持した構成の本光触媒膜は、特定の成分に対する活性が小さいという欠点を解決することができ、また、副生成物の生成による分解の低下を防止することができる。これは、紫外光〜可視光により効率よく活性化される前記構成の酸化タングステン膜と特定成分を効率よく分解等する白金、ルテニウム、酸化ルテニウムの１種又は２種以上の作用が相俟って達成されると考えられる。
【００１２】
この光触媒膜は、担持された白金、ルテニウム、酸化ルテニウムの１種又は２種以上の体積が、酸化タングステン膜表面１ｃｍ2 当たり５×１０ -9 ｃｍ 3 以上、３×１０-7ｃｍ3 以下である。
【００１３】
酸化タングステン膜上への金属担持量については、担持金属の体積が酸化タングステン膜表面１ｃｍ2 当たり５×１０-7ｃｍ3 以下にするのが好ましい。３×１０-7ｃｍ3 ／ｃｍ2 を超える場合、担持金属によって酸化タングステン表面が覆われて活性が減少し、ある特定の成分に対する分解活性が小さくなる場合があるからである。特に、副生成物として例えば酢酸を生成した場合、その分解に対する光触媒活性が大きく低下する。なお、この金属担持量は、この金属による十分な触媒機能の発揮の観点から、酸化タングステン膜表面１ｃｍ2 当たり５×１０-9ｃｍ3 以上とするのがよい。
【００１４】
本発明のうち請求項２に記載の発明は、前記酸化タングステン膜が、スパッタリング法、蒸着法、ゾルゲル法又はＣＶＤ法によって成膜されることを特徴とする請求項１記載の光触媒膜の製造方法である。
【００１５】
スパッタリング法、蒸着法、ゾルゲル法又はＣＶＤ法によって酸化タングステン膜を成膜すると、バインダー等の異物を用いずに膜を形成するため、バインダーの混合による光触媒活性の消失が起こらず、前記した酸化タングステンのもつ本来の活性を得ることができる。
【００１６】
本発明のうち請求項３に記載の発明は、前記白金、ルテニウム、酸化ルテニウムの１種又は２種以上の酸化タングステン膜への担持が、スパッタリング法若しくは蒸着法により行われることを特徴とする請求項１記載の光触媒膜の製造方法である。
【００１７】
光触媒表面に金属微粒子を担持する方法として、一般的には光析出法が知られているが、この方法は担持する際に原料金属成分を含む溶液中に光触媒膜を浸漬し、光照射する必要があり、また、担持後、基板の洗浄も必要で、高速で連続的に担持を行うのに適していない。別の担持方法として、金属イオン、金属コロイドを含む溶液等を光触媒表面に塗布し、焼成する方法があるが、これらの方法では、高温で焼成する必要があるという欠点がある。また、有機物を十分除去するためにより高温で焼成すると、光触媒上の金属微粒子が焼結して微粒子の径が大きくなるという欠点がある。
【００１８】
これに対し、前記の如く構成された光触媒膜は、蒸着またはスパッタ法により酸化タングステン表面に超微粒子を形成しているため、光析出法のように光を照射する必要がなく容易に製造できるばかりか、室温で形成することができので、耐熱性の低い基材を使用して金属担持光触媒を形成することができる。
【００１９】
請求項４は、酸化タングステンのみから構成される酸化タングステン膜に、白金、ルテニウム、酸化ルテニウムの１種又は２種以上を担持した光触媒膜の形成において、イオン、電子線、プラズマ、ラジカルの１種若しくは２種以上で構成される低エネルギー励起粒子線を基板に照射しながら、酸化タングステン膜がスパッタリング法若しくは蒸着法で成膜されることを特徴とする光触媒膜の製造方法である。
【００２０】
このように構成すると、原料を分子レベル、或いは原子レベルまで一旦分解し、基体表面に所定の光触媒膜を形成する蒸着又はスパッタリング法において、膜形成時に前記低エネルギー励起粒子線を照射するため原料分子あるいは原子が高エネルギー状態になり、形成される膜の結晶化が低温でも進行することになる。すなわち、この場合、バインダーを用いず光触媒膜を直接形成するため、バインダー中に光触媒が理もれるといつた問題が無く、高活性な光触媒膜を形成することができるという効果に加えて、従来のバインダーを用いない光触媒膜直接形成法の一つであるゾルゲル法では、例えば、ＴｉＯ2 光触媒膜を結晶化させるために、約５００℃以上の高温加熱が必要であるが、低温でも良好に結晶化した膜を形成することができ、また、透明な膜を容易に得ることができる。
【００２１】
【実施例】
以下、実施例をもって本発明をさらに具体的に説明するが、本発明はこれらの実施例に限定されるものではない。
【００２２】
（実施例１）基板としてバリウム硼珪酸系の無アルカリガラスを、成膜装置としてＲＦマグネトロンスパッタ装置を、ターゲット材料として純度９９．９％以上のＷ０3 を、導入ガスとしてアルゴンと酸素の混合ガスを用い、表１に示す条件で次のようにして酸化タングステン膜を形成した。まず、基板を取り付けた真空室内を真空排気し、所定温度に基板を加熱後、アルゴンと酸素の混合ガスを、アルゴンと酸素の分圧比が所定の値になるよう排気バルブおよび導入ガス流量を調整しつつ導入した。続いて、ターゲットに周波数１３．５６ＭＨｚ、電力６０Ｗの高周波電力を印可し、１６オングストロ−ム／分の成膜速度で、膜厚が０．６μｍとなるよう成膜時間を調整し、成膜を行つた。
【００２３】
上記スパッタリング法による酸化タングステン膜作成終了後、基板をＥＢ（電子ビ−ム）蒸着装置内に取り付け、酸化タングステン膜の上にＥＢ蒸着法にてＰｔ担持を行った。なお、Ｐｔ膜厚は、あらかじめ校正した水晶振動子式の膜厚モニターで確認しながら、膜厚の設定を２０オングストロ−ムとして成膜した。
【００２４】
表１
【００２５】
（実施例２）バリウム硼珪酸系の無アルカリガラスを基体として用い、実施例１と同様の方法にて、酸化タングステン膜を形成した。膜厚は、０．６μｍとなるよう成膜時間を調整した。次に、酸化タングステン膜上に、実施例１と同様の方法でＰｔを担持した。なお、Ｐｔ膜厚の設定は３０オングストロ−ムとして成膜した。
【００２６】
（実施例３）バリウム硼珪酸系の無アルカリガラスを基体として用い、実施例１と同様の方法にて、酸化タングステン膜を形成した。膜厚は、０．６μｍとなるよう成膜時間を調整した。次に、酸化タングステン膜上に、実施例１と同様の方法でＰｔを担持した。なお、Ｐｔ膜厚の設定は２オングストロ−ムとして成膜した。
【００２７】
（実施例４）バリウム硼珪酸系の無アルカリガラスを基体として用い、実施例１と同様の方法にて、酸化タングステン膜を形成した。膜厚は、０．６μｍとなるよう成膜時間を調整した。次に、酸化タングステン膜上に、実施例１と同様の方法でＲｕを担持した。なお、Ｒｕ膜厚の設定は２０オングストロ−ムとして成膜した。
【００２８】
（実施例５）Ｗ０3 を蒸着材料として用い、酸素イオン、酸素ラジカル、酸素プラズマの混合励起線をバリウム硼珪酸系の無アルカリガラス基板に照射しながら、ＥＢ蒸着法により酸化タングステン膜の成膜を行つた。この時、基板下部の基板取り付けプレートにＤＣ電圧を印可し、励起線における荷電粒子の運動エネルギーが８０ｅＶになるよう電圧調整を行つた。励起線照射は、クライオバック社製の励起線源ＥＢＳ−２３を用いた。また、膜厚は６０００オングストロ−ムとなるよう成膜時間を調整した。
【００２９】
（実施例６）バリウム硼珪酸系の無アルカリガラスを基体として用い、実施例１と同様の方法にて、酸化タングステン膜を形成した。膜厚は、０．６μｍとなるよう成膜時間を調整した。次に、酸化タングステン膜上に、実施例１と同様にＥＢ蒸着により酸化ルテニウムを２０オングストロ−ム成膜した。但し、ＥＢ蒸着時に成膜室内のガス圧が５×１０-5Ｔｏｒｒとなる様に、酸素ガスを導入した。
【００３０】
上記蒸着法による酸化タングステン膜作成終了後、基板をＥＢ蒸着装置内に取り付け、酸化タングステン膜の上にＥＢ蒸着法にてＰｔを担持した。なお、Ｐｔ膜厚は、あらかじめ校正した水晶振動子式の膜厚モニターで膜厚を確認しながら、膜厚の設定を２０オングストロ−ムとして成膜を行つた。
【００３１】
（比較例１）シリカゾル（日産化学社製スノーテックスＯ）に、酸化タングステン粉末（関東化学社製Ｗ０3 ）を加えた。但し、固形分重量で酸化タングステンの含有量が２５％、シリカの含有量が７５％になるように設定した。このようにして調整した酸化タングステンの含有シリカゾル溶液に、３ｃｍ×６ｃｍのバリウム硼珪酸系の無アルカリガラス基板を浸漬して該溶液を塗布後、この基板を２００℃で３０分間焼成した。この浸漬・塗布〜焼成を更に２回繰り返し、合計３層の酸化タングステン膜を形成した。
【００３２】
（比較例２）実施例１と同様の方法で、酸化タングステン膜のみを形成した。成膜時間は、酸化タングステン膜の厚みが０．６μｍとなるように、調整した。
【００３３】
（比較例３）実施例１と同様の方法で、酸化タングステン膜のみを形成した。成膜時間は酸化タングステン膜の厚みが０．６μｍとなるように調整した。その後、実施例1と同様の方法でＰｔ膜を５０オングストロ−ムの膜厚設定で成膜した。
【００３４】
（比較例４）実施例１と同様の方法で、酸化タングステン膜のみを形成した。成膜時間は酸化タングステン膜の厚みが０．６μｍとなるように調整した。その後、実施例1と同様の方法でＡｕ膜を２０オングストロ−ムの膜厚設定で成膜した。
【００３５】
（比較例５）実施例１と同様の方法で、酸化タングステン膜のみを形成した。成膜時間は酸化タングステン膜の厚みが０．６μｍとなるように調整した。その後、実施例1と同様の方法でＡｇ膜を２０オングストロ−ムの膜厚設定で成膜した。
【００３６】
（比較例６）実施例１と同様の方法で、酸化タングステン膜のみを形成した。成膜時間は酸化タングステン膜の厚みが０．６μｍとなるように調整した。その後、実施例1と同様の方法でＰｄ膜を２０オングストロ−ムの膜厚設定で成膜した。
【００３７】
（光触媒膜の評価試験）５リットルの容器に、実施例１〜５、及び比較例１〜６の光触媒膜をそれぞれ別個に入れ、悪臭物質の１つであるアセトアルデヒドを１００ｐｐｍの濃度となるよう注入した。次に、６Ｗのブラックライトを用い、各光触媒膜を紫外線で照射し、１、２、３、６時間光照射後のアセトアルデヒド濃度および酢酸の濃度を測定した。結果を表２に示す。
【００３８】
表２
【００３９】
表２に示すように、酸化タングステン粉末をシリカ系バインダーで固定した比較例１の膜は、触媒活性がほとんど認められない。また、スパッタリング法で酸化タングステン膜のみを形成し、Ｐｔ等を担持していない比較例２の膜は、アセトアルデヒドの分解速度が時間と共に低下している。また、生成した酢酸がほとんど分解されておらず、光照射開始ｌｈｒ後から６ｈｒ後にかけての酢酸濃度減少率は２．５％／ｈｒと極めて低い。
【００４０】
一方、Ｐｔを担持した実施例１〜３、Ｒｕを担持した実施例４及びＲｕＯ2 担持した実施例６の膜は、アセトアルデヒドの分解速度が速く、Ｐｔ膜厚が２オングストロ−ムであり最も分解速度の遅い実施例３の膜でも、６ｈｒで９０％以上のアセトアルデヒドが除去されれ、Ｐｔ膜厚がそれぞれ２０オングストロ−ム、３０オングストロ−ムである実施例１、実施例２の膜は、２時間で９９％のアセトアルデヒドが除去されている。また、実施例１〜４の膜の場合、生成する酢酸の分解速度が速く、Ｐｔ担持によって３０％〜８０％／ｈｒ、Ｒｕ又はＲｕＯ2担持によって１６％／ｈｒの平均減少速度が得られている。
【００４１】
励起線を照射しながらＥＢ蒸着で酸化タングステン膜を形成し、Ｐｔを担持した実施例５のサンプルでも、スパッタリングで酸化タングステン膜を形成した実施例１の膜とほば同等の高速浄化性能が得られている。この光触媒膜は、成膜時に基板加熱をする必要がなく、低温で形成できるため、耐熱温度の低い基材上に形成できるという利点がある。
【００４２】
酸化タングステン膜上にＰｔを５０オングストロ−ムの厚みで成膜した比較例３の膜（Ｐｔの体積が酸化タングステン膜表面１ｃｍ2 当たり５×１０-7ｃｍ3を超えている）は、Ｐｔを成膜しない比較例２の膜とアセトアルデヒド分解速度が同レベルで、Ｐｔを担持した効果が無い。
【００４３】
本発明に用いる金属以外のＡｕ、Ａｇ、Ｐｄをそれぞれ担持した比較例４〜６の膜は、アセトアルデヒドの分解速度が時間と共に低下する傾向がある。また、光照射開始１時間後から６時間後にかけての酢酸濃度の平均減少速度が１０％／ｈｒ以下となつており、酢酸濃度の減少速度が遅い。
【００４４】
（比較例７）基板としてバリウム硼珪酸系の無アルカリガラスを、成膜装置としてＲＦマグネトロンスパッタ装置を、ターゲット材料として純度９９．９％以上のＴｉＯ2を、導入ガスとしてアルゴンと酸素の混合ガスを用い、表３に示す条件で次のようにして酸化チタン膜を形成した。まず、基板を取り付けた真空室内を真空排気し、所定温度に基板を加熱後、アルゴンと酸素の混合ガスを、アルゴンと酸素の分圧比が所定の値になるよう排気バルブおよび導入ガス流量を調整しつつ導入した。続いて、ターゲットに周波数１３．５６ＭＨｚ、電力４００Ｗの高周波電力を印可し、２５オングストロ−ム／分の成膜速度で、膜厚が０．６μｍとなるよう成膜時間を調整し、成膜を行つた。
【００４５】
表３
【００４６】
（光触媒膜の評価試験）５リットルの容器に、実施例１、実施例４及び比較例７の光触媒膜をそれぞれ別個に入れ、悪臭物質の１つであるアセトアルデヒドを１００ｐｐｍの濃度となるよう注入した。次に、厚み１ｍｍのポリカ−ボネ−ト板により紫外光をカットした６Ｗの昼光色蛍光灯を用い、各光触媒膜を可視光で照射し、２、４、６、１０時間光照射後のアセトアルデヒド濃度および酢酸の濃度を測定した。結果を表４に示す。
【００４７】
表４
【００４８】
表４に示すように、酸化タングステン膜にＰｔを担持した実施例１のサンプルは、紫外光を含まない可視光の照射によって、１０ｈｒでアセトアルデヒドが９３％分解しており、大きな可視光活性が得られている。また、Ｒｕを担持した実施例４の膜では、１０ｈｒで３３％のアセトアルデヒドが分解されている。一方、従来の代表的な光触媒材料である酸化チタンを使つた比較例７の膜は、可視光照射１０ｈｒ後もアセトアルデヒドが全く分解しなかつた。
【００４９】
【発明の効果】
以上説明したように、本発明では、光触媒膜をバインダーを用いること無く形成し、なおかつＰｔ、Ｒｕ又はＲｕＯ2 を担持するため、酢酸等の比較的分解しにくい物質に対する分解活性が高い。このため、副生成物として、分解しにくい物質が生成しても活性が低下せず、高活性の状態が維持される。従来の代表的な光触媒材料である酸化チタンは、活性を得るために紫外光を照射する必要が有つたため、太陽光、蛍光灯等の自然光を照射した場合、微量の紫外光しか利用できず、大きな活性を得ることができなかつた。本発明による光触媒膜は、紫外光を含まない可視光でも大きな活性を得ることができる。このため、自然光照射下で大きな活性を得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photocatalyst film, and more particularly to a photocatalyst film that can exhibit catalytic activity even in the visible light region.
[0002]
[Prior art]
When the photocatalyst is irradiated with light having a wavelength greater than the band gap, photoexcitation generates electrons in the conduction band and holes in the valence band. The strong reducing power of electrons generated by this photoexcitation and the strong oxidizing power of holes are considered to be used for the decomposition and purification of organic matter, the decomposition of water, the removal of nitrogen oxides, the decomposition and fixation of carbon dioxide, etc. In the field of antibacterial and purification, practical use is being promoted in part.
[0003]
The most typical material for the photocatalyst is titanium oxide. Titanium oxide is highly active and has excellent chemical stability, and its activity as a photocatalyst lasts semipermanently. In addition, it is harmless and harmless to the human body and has the advantages of being abundant and inexpensive as a resource. However, in order to activate titanium oxide, which is a kind of n-type semiconductor, as a catalyst, the band gap is about 3.2 eV in the case of an anatase crystal that provides a large activity, and it is necessary to irradiate ultraviolet light of 380 nm or less. There is. Therefore, for example, an air cleaner using a titanium oxide photocatalyst incorporates a black light or a germicidal lamp that irradiates ultraviolet light in order to deodorize odor components caused by tobacco in the air. Even if titanium oxide is irradiated with natural light such as white fluorescent light, daylight fluorescent light, sunlight, etc., it is possible to obtain a little activity with a small amount of ultraviolet light, and studies are gradually progressing in the field of antibacterial and antifouling, NO Consideration of X purification is also underway. However, there are drawbacks in that the activity is small and the energy efficiency is poor.
[0004]
In order to eliminate such drawbacks and to obtain photocatalytic activity of titanium oxide with visible light, for example, a study of doping various materials into titanium oxide has been conducted, and in recent years, doping by an ion implantation method has attracted attention (Japanese Patent Application Laid-Open No. Hei 9 (1994)). 9-262482, etc.). However, although the absorption of visible light can be obtained by doping, there is a problem that the catalytic activity generally decreases, and the decrease in the catalytic activity is improved by using the ion implantation method, but a large area substrate is continuously formed. However, there is a problem that it is difficult to process and the mass productivity is poor.
[0005]
In order to solve the above problem of titanium oxide, Fe 2 O 3 , CdS, CdSe, GaP, and the like have been studied as materials that absorb visible light in addition to titanium oxide. However, Fe 2 O 3 has almost no activity, and CdS, CdSe, and GaP have poor stability even if the activity is initially obtained, so there is a problem of decrease in activity and dissolution in water.
[0006]
WO 3 is also known to have activity in visible light, but is generally said to have poor stability and reliability. Furthermore, as a result of investigations by the inventors, the tungsten oxide photocatalyst has an extremely small decomposition activity with respect to a specific component and easily generates a by-product. The by-product is adsorbed on the surface of the tungsten oxide film and has a high activity. There is a problem of lowering. For example, when acetaldehyde, which is one of typical odor components, is decomposed with a tungsten oxide photocatalyst, a large amount of acetic acid is generated as a by-product. This acetic acid is adsorbed on the tungsten oxide surface, and the decomposition rate of acetic acid is extremely slow, so that the photocatalytic activity is greatly reduced.
[0007]
[Problems to be solved by the invention]
Therefore, the present invention aims to provide a photocatalyst that shifts the light absorption band to the visible light region to express catalytic activity and that is stably maintained without being reduced by a specific substance. To do.
[0008]
[Means for Solving the Problems]
In order to achieve such an object, as a result of intensive research on the structure of the tungsten oxide film and the combination of the tungsten oxide film with attention to tungsten oxide, one or two kinds of platinum, ruthenium, and ruthenium oxide are used for the tungsten oxide film that does not use a binder. The present inventors have found that the photocatalyst film supporting the above absorbs light in the ultraviolet light region and visible light region and exhibits stable catalytic activity, thereby completing the present invention.
[0009]
That is, the invention described in claim 1 of the present invention is a photocatalytic film in which one or more of platinum , ruthenium, and ruthenium oxide are supported on a tungsten oxide film composed of only tungsten oxide, The volume of one or more of platinum, ruthenium, and ruthenium oxide is 5 × 10 −9 cm 3 or more and 3 × 10 −7 cm 3 or less per 1 cm 2 of the tungsten oxide film surface. It is a photocatalytic film.
[0010]
Here, “tungsten oxide film composed only of tungsten oxide” means a film composed only of tungsten oxide without using a binder. Compared to the case where the photocatalyst is used in the powder state, the tungsten oxide film thus configured is required to separate and recover only the catalyst powder from the reaction system after the powder catalyst is purified by the catalyst. However, this is not necessary. Second, when compared with a film in which tungsten particles are formed using a binder such as silica or alumina, such a film absorbs visible light and exhibits catalytic activity. Even if the activity is almost lost, such a problem does not occur and the original activity of tungsten oxide can be obtained.
[0011]
In addition, the present photocatalyst film having a structure in which one or more of platinum, ruthenium, and ruthenium oxide is supported on the surface of the tungsten oxide film can solve the disadvantage that the activity with respect to a specific component is small. It is possible to prevent the degradation of decomposition due to the generation of the product. This is due to the combined effects of one or more of platinum, ruthenium, and ruthenium oxide that efficiently decomposes the specific component and the tungsten oxide film having the above-described structure that is efficiently activated by ultraviolet light to visible light. Expected to be achieved.
[0012]
In this photocatalyst film , the volume of one or more of platinum, ruthenium, and ruthenium oxide supported is 5 × 10 −9 cm 3 or more and 3 × 10 −7 cm 3 or less per 1 cm 2 of the tungsten oxide film surface. Oh Ru.
[0013]
With respect to the amount of metal supported on the tungsten oxide film, the volume of the supported metal is preferably 5 × 10 −7 cm 3 or less per 1 cm 2 of the tungsten oxide film surface. This is because if it exceeds 3 × 10 −7 cm 3 / cm 2 , the tungsten oxide surface is covered with the supported metal and the activity is reduced, and the decomposition activity for a specific component may be reduced. In particular, when acetic acid is produced as a by-product, for example, the photocatalytic activity for its decomposition is greatly reduced. Incidentally, the amount of metal supported is, in terms of exhibiting a sufficient catalytic function by the metal, it is preferable to oxidation tungsten film surface 1 cm 2 per 5 × 10 -9 cm 3 or more.
[0014]
The invention according to claim 2 of the present invention, the tungsten oxide film, a sputtering method, an evaporation method, a manufacturing method of the photocatalyst film according to claim 1, characterized in that it is deposited by a sol-gel method or the CVD method It is.
[0015]
When a tungsten oxide film is formed by sputtering, vapor deposition, sol-gel method or CVD method, the film is formed without using a foreign substance such as a binder. The original activity of can be obtained.
[0016]
The invention according to a third aspect of the present invention, the platinum, ruthenium, claims supported to one or more of the tungsten oxide film of ruthenium oxide, characterized in that it is performed by a sputtering method or a vapor deposition method Item 2. A method for producing a photocatalytic film according to Item 1.
[0017]
As a method for supporting metal fine particles on the surface of the photocatalyst, a photoprecipitation method is generally known, but this method requires immersing the photocatalyst film in a solution containing the raw metal component and irradiating with light. In addition, it is necessary to clean the substrate after loading, which is not suitable for continuous loading at high speed. As another supporting method, there is a method in which a solution containing a metal ion, a metal colloid, or the like is applied to the surface of the photocatalyst and baked. However, these methods have a drawback in that they need to be baked at a high temperature. Further, when firing at a higher temperature in order to sufficiently remove the organic matter, there is a drawback that the metal fine particles on the photocatalyst are sintered and the diameter of the fine particles is increased.
[0018]
On the other hand, the photocatalyst film configured as described above has ultrafine particles formed on the surface of tungsten oxide by vapor deposition or sputtering, so that it can be easily manufactured without the need to irradiate light unlike the photodeposition method. Alternatively, since it can be formed at room temperature, a metal-supported photocatalyst can be formed using a substrate having low heat resistance.
[0019]
Claim 4, the tungsten oxide film constituted only tungsten oxide, platinum, ruthenium, in the formation of the photocatalytic film carrying one or more of ruthenium oxide, ion, electron beam, plasma, one radical or while being irradiated with low-energy excited particle beam on the substrate composed of two or more, the tungsten oxide film is a manufacturing method of a photocatalyst film you characterized in that it is formed by sputtering or vapor deposition.
[0020]
With this configuration, in the vapor deposition or sputtering method in which the raw material is once decomposed to the molecular level or the atomic level and a predetermined photocatalytic film is formed on the surface of the substrate, the raw material molecule is irradiated with the low energy excited particle beam at the time of film formation. Alternatively, the atoms are in a high energy state, and crystallization of the formed film proceeds even at a low temperature. That is, in this case, since the photocatalyst film is directly formed without using the binder, there is no problem when the photocatalyst is understood in the binder, and in addition to the effect that a highly active photocatalyst film can be formed, In the sol-gel method, which is one of the photocatalyst film direct forming methods without using any binder, for example, in order to crystallize the TiO 2 photocatalyst film, high temperature heating of about 500 ° C. or more is necessary. Thus, a transparent film can be easily obtained.
[0021]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
[0022]
(Example 1) The alkali-free glass of barium borosilicate as a substrate, RF magnetron sputtering apparatus, the W0 3 or more 99.9% purity as a target material, a mixed gas of argon and oxygen as an introduction gas as a film forming apparatus A tungsten oxide film was formed under the conditions shown in Table 1 as follows. First, the vacuum chamber in which the substrate is mounted is evacuated, the substrate is heated to a predetermined temperature, the mixed gas of argon and oxygen is adjusted, and the exhaust valve and the introduction gas flow rate are adjusted so that the partial pressure ratio of argon and oxygen becomes a predetermined value. While introducing. Subsequently, a high frequency power with a frequency of 13.56 MHz and a power of 60 W was applied to the target, and the film formation time was adjusted so that the film thickness became 0.6 μm at a film formation speed of 16 Å / min. I went.
[0023]
After completion of the tungsten oxide film formation by the sputtering method, the substrate was mounted in an EB (electron beam) vapor deposition apparatus, and Pt was supported on the tungsten oxide film by the EB vapor deposition method. The film thickness of the Pt film was set to 20 angstroms while checking with a crystal oscillator type film thickness monitor calibrated in advance.
[0024]
Table 1
[0025]
Example 2 A tungsten oxide film was formed in the same manner as in Example 1 using barium borosilicate non-alkali glass as a substrate. The film formation time was adjusted so that the film thickness was 0.6 μm. Next, Pt was supported on the tungsten oxide film by the same method as in Example 1. The Pt film thickness was set to 30 Å.
[0026]
Example 3 A tungsten oxide film was formed in the same manner as in Example 1 using barium borosilicate non-alkali glass as a substrate. The film formation time was adjusted so that the film thickness was 0.6 μm. Next, Pt was supported on the tungsten oxide film by the same method as in Example 1. The Pt film thickness was set to 2 angstroms.
[0027]
Example 4 A tungsten oxide film was formed in the same manner as in Example 1 using a barium borosilicate non-alkali glass as a substrate. The film formation time was adjusted so that the film thickness was 0.6 μm. Next, Ru was supported on the tungsten oxide film by the same method as in Example 1. The Ru film thickness was set to 20 Å.
[0028]
(Example 5) W0 3 as a vapor deposition material, oxygen ions, oxygen radicals, while the mixed excitation line of the oxygen plasma was irradiated to the alkali-free glass substrate of barium borosilicate, deposition of the tungsten oxide film by EB vapor deposition method I went. At this time, a DC voltage was applied to the substrate mounting plate below the substrate, and the voltage was adjusted so that the kinetic energy of the charged particles in the excitation line was 80 eV. Excitation ray irradiation was performed using an excitation ray source EBS-23 manufactured by Cryobach. The film formation time was adjusted so that the film thickness was 6000 angstroms.
[0029]
Example 6 A tungsten oxide film was formed in the same manner as in Example 1 using a barium borosilicate non-alkali glass as a substrate. The film formation time was adjusted so that the film thickness was 0.6 μm. Next, on the tungsten oxide film, 20 Å of ruthenium oxide was formed by EB vapor deposition in the same manner as in Example 1. However, oxygen gas was introduced so that the gas pressure in the deposition chamber was 5 × 10 −5 Torr during EB deposition.
[0030]
After completion of the tungsten oxide film formation by the above vapor deposition method, the substrate was mounted in an EB vapor deposition apparatus, and Pt was supported on the tungsten oxide film by the EB vapor deposition method. The Pt film thickness was set to 20 angstrom while the film thickness was checked with a crystal oscillator type film thickness monitor calibrated in advance.
[0031]
(Comparative Example 1) Tungsten oxide powder (W0 3 manufactured by Kanto Chemical Co., Inc.) was added to silica sol (Snowtex O manufactured by Nissan Chemical Co., Ltd.). However, the tungsten oxide content was set to 25% and the silica content was set to 75% in terms of solid content. A 3 cm × 6 cm barium borosilicate alkali-free glass substrate was immersed in the thus prepared tungsten oxide-containing silica sol solution, and the solution was applied. The substrate was then baked at 200 ° C. for 30 minutes. This dipping / coating / firing was further repeated twice to form a total of three layers of tungsten oxide films.
[0032]
(Comparative Example 2) In the same manner as in Example 1, only a tungsten oxide film was formed. The film formation time was adjusted so that the thickness of the tungsten oxide film was 0.6 μm.
[0033]
(Comparative Example 3) In the same manner as in Example 1, only a tungsten oxide film was formed. The film formation time was adjusted so that the tungsten oxide film had a thickness of 0.6 μm. Thereafter, a Pt film was formed in the same manner as in Example 1 with a film thickness setting of 50 Å.
[0034]
(Comparative Example 4) In the same manner as in Example 1, only a tungsten oxide film was formed. The film formation time was adjusted so that the tungsten oxide film had a thickness of 0.6 μm. Thereafter, an Au film was formed at a thickness of 20 Å by the same method as in Example 1.
[0035]
(Comparative Example 5) In the same manner as in Example 1, only a tungsten oxide film was formed. The film formation time was adjusted so that the tungsten oxide film had a thickness of 0.6 μm. Thereafter, an Ag film was formed in the same manner as in Example 1 with a film thickness setting of 20 angstroms.
[0036]
(Comparative Example 6) In the same manner as in Example 1, only a tungsten oxide film was formed. The film formation time was adjusted so that the tungsten oxide film had a thickness of 0.6 μm. Thereafter, a Pd film was formed in the same manner as in Example 1 with a film thickness setting of 20 angstroms.
[0037]
(Evaluation test of photocatalyst film) The photocatalyst films of Examples 1 to 5 and Comparative Examples 1 to 6 are separately put in a 5 liter container, and acetaldehyde, which is one of malodorous substances, is injected to a concentration of 100 ppm. did. Next, each photocatalyst film was irradiated with ultraviolet rays using a 6 W black light, and the acetaldehyde concentration and acetic acid concentration after 1, 2, 3, and 6 hours of light irradiation were measured. The results are shown in Table 2.
[0038]
Table 2
[0039]
As shown in Table 2, the catalyst of Comparative Example 1 in which the tungsten oxide powder is fixed with a silica-based binder has almost no catalytic activity. Further, in the film of Comparative Example 2 in which only the tungsten oxide film is formed by the sputtering method and does not carry Pt or the like, the decomposition rate of acetaldehyde decreases with time. Further, the generated acetic acid is hardly decomposed, and the acetic acid concentration decrease rate from 1 hour after light irradiation start to 6 hours later is as extremely low as 2.5% / hr.
[0040]
On the other hand, the membranes of Examples 1 to 3 loaded with Pt, Example 4 loaded with Ru and Example 6 loaded with RuO 2 had the highest decomposition rate of acetaldehyde, and the Pt film thickness was 2 angstroms. Even in the film of Example 3 having a low speed, 90% or more of acetaldehyde was removed in 6 hours, and the films of Examples 1 and 2 having Pt film thicknesses of 20 angstroms and 30 angstroms, respectively, 99% of acetaldehyde is removed over time. In the case of the membranes of Examples 1 to 4, the decomposition rate of the acetic acid produced is high, and an average reduction rate of 30% to 80% / hr by Pt loading and 16% / hr by Ru or RuO 2 loading is obtained. Yes.
[0041]
The sample of Example 5 in which a tungsten oxide film was formed by EB deposition while irradiating excitation rays and Pt was supported, had a high-speed purification performance almost equivalent to the film of Example 1 in which a tungsten oxide film was formed by sputtering. It has been. This photocatalyst film does not need to be heated at the time of film formation and can be formed at a low temperature, so that it can be formed on a substrate having a low heat resistance temperature.
[0042]
The film of Comparative Example 3 (Pt volume exceeds 5 × 10 −7 cm 3 per 1 cm 2 of tungsten oxide film surface) in which Pt is formed on the tungsten oxide film to a thickness of 50 Å The acetaldehyde decomposition rate is at the same level as the film of Comparative Example 2 where no film is formed, and there is no effect of supporting Pt.
[0043]
In the films of Comparative Examples 4 to 6 each carrying Au, Ag, and Pd other than the metal used in the present invention, the decomposition rate of acetaldehyde tends to decrease with time. In addition, the average rate of decrease in acetic acid concentration from 1 hour to 6 hours after the start of light irradiation is 10% / hr or less, and the rate of decrease in acetic acid concentration is slow.
[0044]
Comparative Example 7 Barium borosilicate non-alkali glass as a substrate, RF magnetron sputtering apparatus as a film forming apparatus, TiO 2 having a purity of 99.9% or more as a target material, and a mixed gas of argon and oxygen as an introduction gas And a titanium oxide film was formed as follows under the conditions shown in Table 3. First, the vacuum chamber in which the substrate is mounted is evacuated, the substrate is heated to a predetermined temperature, the mixed gas of argon and oxygen is adjusted, and the exhaust valve and the introduction gas flow rate are adjusted so that the partial pressure ratio of argon and oxygen becomes a predetermined value. While introducing. Subsequently, high frequency power having a frequency of 13.56 MHz and a power of 400 W was applied to the target, and the film formation time was adjusted so that the film thickness became 0.6 μm at a film formation speed of 25 Å / min. I went.
[0045]
Table 3
[0046]
(Evaluation test of photocatalyst film) The photocatalyst films of Example 1, Example 4 and Comparative Example 7 were separately placed in a 5 liter container, and acetaldehyde, which is one of malodorous substances, was injected to a concentration of 100 ppm. . Next, using a 6 W daylight fluorescent lamp with ultraviolet light cut by a 1 mm thick polycarbonate plate, each photocatalyst film was irradiated with visible light and acetaldehyde concentration after 2, 4, 6, 10 hours of light irradiation And the concentration of acetic acid was measured. The results are shown in Table 4.
[0047]
Table 4
[0048]
As shown in Table 4, in the sample of Example 1 in which Pt is supported on a tungsten oxide film, acetaldehyde was decomposed by 93% in 10 hours by irradiation with visible light not containing ultraviolet light, and a large visible light activity was obtained. It has been. Further, in the membrane of Example 4 supporting Ru, 33% acetaldehyde was decomposed in 10 hours. On the other hand, in the film of Comparative Example 7 using titanium oxide, which is a typical conventional photocatalyst material, acetaldehyde was not decomposed at all even after 10 hours of visible light irradiation.
[0049]
【The invention's effect】
As described above, in the present invention, the photocatalytic film is formed without using a binder, and supports Pt, Ru, or RuO 2, and therefore has a high decomposing activity for substances that are relatively difficult to decompose, such as acetic acid. For this reason, even if a substance that is difficult to decompose is generated as a by-product, the activity does not decrease and a highly active state is maintained. Titanium oxide, which is a typical photocatalyst material in the past, needed to be irradiated with ultraviolet light in order to obtain activity, so only a small amount of ultraviolet light could be used when irradiated with natural light such as sunlight or fluorescent lamps. I couldn't get great activity. The photocatalytic film according to the present invention can obtain great activity even with visible light that does not contain ultraviolet light. For this reason, great activity can be obtained under natural light irradiation.
Claims (4)
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| JP5532504B2 (en) * | 2009-03-05 | 2014-06-25 | 住友電気工業株式会社 | Photocatalytic element |
| KR101804599B1 (en) * | 2013-10-22 | 2017-12-06 | (주)엘지하우시스 | Method for preparing photocatalyst and photocatalyst prepared therefrom |
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