Department of Chemistry, University of Bath, Bath, BA2 7AY, United Kingdom.
Faraday Discuss. 2012;155:309-22; discussion 349-56. doi: 10.1039/c1fd00079a.
The kinetics of light-driven oxygen evolution at polycrystalline alpha-Fe2O3 layers prepared by aerosol-assisted chemical vapour deposition has been studied using intensity modulated photocurrent spectroscopy (IMPS). Analysis of the frequency-dependent IMPS response gives information about the competition between the 4-electron oxidation of water by photogenerated holes and losses due to electron-hole recombination via surface states. The very slow kinetics of oxygen evolution indicates the presence of a kinetic bottleneck in the overall process. Surface treatment of the alpha-Fe2O3 with dilute cobalt nitrate solution leads to a remarkable improvement in the photocurrent response, but contrary to expectation, the results of this study show that this is not due to catalysis of hole transfer but is instead the consequence of almost complete suppression of surface recombination.
利用强度调制光电流谱（IMPS）研究了气溶胶辅助化学气相沉积法制备的多晶α-Fe2O3 层的光驱动氧气析出动力学。对频率相关的 IMPS 响应的分析提供了关于水的 4 电子光生空穴氧化与通过表面态的电子-空穴复合损失之间竞争的信息。氧气析出的非常缓慢的动力学表明整个过程中存在动力学瓶颈。用稀硝酸钴溶液对α-Fe2O3 进行表面处理会显著改善光电流响应，但与预期相反，本研究的结果表明，这不是由于空穴转移的催化作用，而是表面复合几乎完全抑制的结果。
