水の完全分解反応に対するGa_2O_3光触媒の古漬性化

摘要

光触媒による水の完全分解反応は，基本的かつ重要な光触媒反応の一つである。この反応は，反応のギプス自由エネルギー変化が25℃で△G~0＝237kJ/molという大きな正の値を示している。これは，この反応が常圧・常温では自発的には進行せず，反応を進行させるためには電気エネルギーのようなエネルギーを加える必要があることを示している。また逆に，この反応が常温で進行させれば，大きなエネルギーが化学エネルギーとして蓄えられる。%Photocatalytic overall splitting of H_2O is one of the important photocatalytic reactions and has been studying widely to convert photoenergy into chemical energy directly under solar irradiation. However, the performances of the photocatalysts for the reaction, not only the photocatalytic activity but also the photoresponse, are insufficient for further applications. In this review, we summarize the factors for improving the photocatalytic activity referred to the previous studies under developing the effective photocatalysts for the H_2O splitting and show the improvement of the photocatalytic activity of Ga_2O_3 photocatalysts toward the overall splitting of H_2O. Particularly, as for the improvements of the photocatalytic activity of Ga_2O_3, we introduce the improvement of the photocatalytic activity by controlling the surface state of Ga_2O_3, such as combining the effective co-catalysts, as well as the morphology and the bulk states by changing the preparation condition and doping Zn ion, respectively.