水分解光触媒の光励起キャリア－ダイナミクス: キャリアダイナミクスと定常反応活性との比較

摘要

エネルギー問題や環境問題を解決する方法として太陽光rnを用いて水から水素を製造し，有害汚染物質を分解する光rn触媒が注目されている．この光触媒は，酸化チタンなrnどの半導体のバンドギャップを光励起して生成した光励起rn電子や正孔がそれぞれ還元反応と酸化反応を引き起こすたrnめ，その量子効率や反応選択性は，電子正孔再結合速度だrnけではなく，反応分子への電荷移動速度，電荷移動を受けrnた反応分子の反応過程や失活過程に依存する．%Catalytic activity of some photocatalysts, such as Pt/TiO_2, NaTaO_3, and S-doped TiO_2, for water splitting reaction has been evaluated by time-resolved IR (TR-IR) spectroscopy. The photocatalytic quantum yield is determined by ratio of the rates of electron-hole pair recombination and the charge consuming reactions. TR-IR enables to measure both of the rates. The information on the recombination and reaction rates is indispensable to develop highly efficient photocatalysts. TR-IR enables us to measure both of the rates, whereas the conventional methods of the catalyst characterization or steady-state activity measurements do not. We have demonstrated that TR-IR can be used to estimate the effects of the catalyst-modifications on the rates of the recombination and the charge transfer to reactants.