Understanding the reaction kinetics of photocatalytic water splitting is important for the solar energy conversion field. Particularly, identifying the main obstacle in solar water oxidation is intriguing for efforts to promote the energy conversion efficiency. Herein, we take WO3 and cesium treated WO3 as prototypical models to disclose the reaction kinetics of photocatalytic water oxidation and found that the lack of long-lived surface holes is the bottleneck in the photocatalytic process. Analysis of the kinetic barriers of the surface catalytic reactions indicates that the water oxidation on WO3 is kinetically fast, whereas surface treatment of WO3 with cesium carbonate would enlarge the reaction energy barrier but unexpectedly increase the photocatalytic water oxidation rate. A further comparison of the charge dynamics by surface photovoltage and intensity modulated photocurrent spectroscopy reveals that the increased surface hole density due to the suppression of charge recombination accounts for the improvement in the photocatalytic activity.

中文翻译：

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揭示WO3上光催化水氧化的动力学。

理解光催化水分解的反应动力学对太阳能转化领域很重要。特别地，确定太阳能氧化中的主要障碍对于提高能量转换效率的努力很有趣。在本文中，我们以WO3和铯处理的WO3为原型模型，揭示了光催化水氧化的反应动力学，发现缺乏长寿命的表面孔是光催化过程中的瓶颈。对表面催化反应的动力学势垒的分析表明，WO3上的水氧化在动力学上是快速的，而用碳酸铯对WO3进行表面处理将扩大反应能垒，但出乎意料地提高了光催化水的氧化速率。