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Aspects of the Water Splitting Mechanism on (Ga1-xZnx)(N1-xOx) Photocatalyst Modified with Rh2-yCryO3 Cocatalyst
被引:135
作者:
Hisatomi, Takashi
[1
]
Maeda, Kazuhiko
[1
]
Takanabe, Kazuhiro
[1
]
Kubota, Jun
[1
]
Domen, Kazunari
[1
]
机构:
[1] Univ Tokyo, Dept Chem Syst Engn, Sch Engn, Bunkyo Ku, Tokyo 1138656, Japan
基金:
日本科学技术振兴机构;
日本学术振兴会;
关键词:
VISIBLE-LIGHT-DRIVEN;
RESOLVED INFRARED-ABSORPTION;
HYDROGEN EVOLUTION REACTION;
NANOCRYSTALLINE TIO2 FILMS;
MIXED-OXIDE NANOPARTICLES;
SOLID-SOLUTION;
TRANSIENT ABSORPTION;
CORE/SHELL NANOPARTICLES;
PHOTOCHEMICAL REDUCTION;
NATAO3;
PHOTOCATALYSTS;
D O I:
10.1021/jp9079662
中图分类号:
O64 [物理化学(理论化学)、化学物理学];
学科分类号:
070304 ;
081704 ;
摘要:
Aspects of the water splitting mechanism on (Ga1-xZnx)(N1-xOx) 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 Rh2-yCryO3 cocatalyst significantly affected the photocatalytic behavior with varying light intensity. When the loading amount of Rh2-yCryO3 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, AM 1.5, the water splitting rate using modified (Ga1-xZnx)(N1-xOx) remained under the light-intensity-proportional regime. The isotope effect of H2O/D2O on overall water splitting using Rh2-yCryO3/(Ga1-xZnx)(N1-xOx) 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 carriers present in the Rh2-yCryO3/(Ga1-xZnx)(N1-xOx) , which should become available for redox reactions on the surface of the photocatalyst. A kinetic model of photocatalytic water splitting proposed in this work suggests that the reaction probability of photoexcited holes for O-2 evolution versus recombination with intrinsic electrons of the photocatalyst determines the photocatalytic activity of the Rh2-yCryO3/(Ga1-xZnx)(N1-xOx).
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页码:21458 / 21466
页数:9
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