Dynamics of photogenerated holes in surface modified α-Fe2O3 photoanodes for solar water splitting
Dynamics of photogenerated holes in surface modified α-Fe2O3 photoanodes for solar water splitting
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DOI：
10.1073/pnas.1118326109
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发表时间：
2012-09-25
影响因子：
11.1
通讯作者：
Durrant, James R.
中科院分区：
文献类型：
--
作者：
Barroso, Monica;Mesa, Camilo A.;Durrant, James R.
本文论述了减少的外部电偏压所需的水光电解与赤铁矿光阳极，观察到这样的电极表面处理的起源。我们考虑两种替代的表面改性：钴氧代/羟基（CoOx）覆盖层，以前报道的功能作为一个有效的水氧化电催化剂，和氧化镓覆盖层，报告钝化赤铁矿表面状态。这些复合电极在外加偏压下的瞬态吸收研究表明，阴极位移的光电流发生后观察到的每个表面改性是伴随着一个类似的阴极位移的外观的长寿命的赤铁矿光空穴，由于延迟的电子/空穴复合。较慢的电子/空穴复合的起源主要分配给增强的电子耗尽在Fe 2 O3对于一个给定的外加偏压。
This paper addresses the origin of the decrease in the external electrical bias required for water photoelectrolysis with hematite photoanodes, observed following surface treatments of such electrodes. We consider two alternative surface modifications: a cobalt oxo/hydroxo-based (CoOx) overlayer, reported previously to function as an efficient water oxidation electrocatalyst, and a Ga2O3 overlayer, reported to passivate hematite surface states. Transient absorption studies of these composite electrodes under applied bias showed that the cathodic shift of the photocurrent onset observed after each of the surface modifications is accompanied by a similar cathodic shift of the appearance of long-lived hematite photoholes, due to a retardation of electron/hole recombination. The origin of the slower electron/hole recombination is assigned primarily to enhanced electron depletion in the Fe2O3 for a given applied bias.