Aspects of the Water Splitting Mechanism on (Ga1−xZnx)(N1−xOx) Photocatalyst Modified with Rh2−yCryO3 Cocatalyst

作者：Takashi Hisatomi, Kazuhiko Maeda, Kazuhiro Takanabe, Jun Kubota, Kazunari Domen · 发表于：The Journal of Physical Chemistry C · 年份：2009 · DOI：10.1021/jp9079662 · 被引用次数：164 · 研究领域：Advanced Photocatalysis Techniques、Ga2O3 and related materials、ZnO doping and properties

Aspects of the water splitting mechanism on (Ga 1− x Zn x )(N 1− x O x ) photocatalyst powder are discussed on the basis of the effects of cocatalyst loading, light intensity, hydrogen/deuterium isotopes, and reaction temperature on photocatalytic activity. The loading amount of Rh 2− y Cr y O 3 cocatalyst significantly affected the photocatalytic behavior with varying light intensity. When the loading amount of Rh 2− y Cr y O 3 as a H 2 evolution cocatalyst was insufficient, the reaction order for light intensity was lower than unity. This is because photoexcited electrons accumulated in the photocatalyst and recombined with photoexcited holes more frequently than they contributed to the water splitting reaction. When a sufficient amount of cocatalyst was loaded, on the other hand, accumulation of photoexcited electrons was suppressed and the water splitting rate increased monotonically with light intensity. At a light intensity equivalent to solar irradiation, AM1.5, the water splitting rate using modified (Ga 1− x Zn x )(N 1− x O x ) remained under the light-intensity-proportional regime. The isotope effect of H 2 O/D 2 O on overall water splitting using Rh 2− y Cr y O 3 /(Ga 1− x Zn x )(N 1− x O x ) was smaller than previously reported for electrochemical H 2 evolution reactions. Moreover, the apparent activation energy of the overall water splitting was as small as 8 kJ mol −1, and independent of the reactants. These results arise from the limited number of photoexcited ...