Ma Yimeng, Le Formal Florian, Kafizas Andreas, Pendlebury Stephanie R, Durrant James R
Department of Chemistry , Imperial College London , South Kensington Campus , London , SW7 2AZ , UK . Email:
J Mater Chem A Mater. 2015 Nov 7;3(41):20649-20657. doi: 10.1039/c5ta05826k. Epub 2015 Sep 21.
In this paper, we compared for the first time the dynamics of photogenerated holes in BiVO photoanodes with and without CoPi surface modification, employing transient absorption and photocurrent measurements on microsecond to second timescales. CoPi surface modification is known to cathodically shift the water oxidation onset potential; however, the reason for this improvement has not until now been fully understood. The transient absorption and photocurrent data were analyzed using a simple kinetic model, which allows quantification of the competition between electron/hole recombination and water oxidation. The results of this model are shown to be in excellent agreement with the measured photocurrent data. We demonstrate that the origin of the improvement of photocurrent onset resulting from CoPi treatment is primarily due to retardation of back electron/hole recombination across the space charge layer; no evidence of catalytic water oxidation CoPi was observed.
在本文中，我们首次通过在微秒至秒时间尺度上进行瞬态吸收和光电流测量，比较了有和没有CoPi表面修饰的BiVO光阳极中光生空穴的动力学。已知CoPi表面修饰会使水氧化起始电位发生阴极偏移；然而，迄今为止，这种改善的原因尚未完全理解。使用简单的动力学模型对瞬态吸收和光电流数据进行了分析，该模型能够量化电子/空穴复合与水氧化之间的竞争。该模型的结果与测得的光电流数据显示出极好的一致性。我们证明，CoPi处理导致光电流起始改善的原因主要是由于空间电荷层中反向电子/空穴复合的延迟；未观察到CoPi催化水氧化的证据。
