Nandjou Fredy, Haussener Sophia
Laboratory of Renewable Energy Science and Engineering, EPFL, Station 9, 1015, Lausanne, Switzerland.
ChemSusChem. 2019 May 8;12(9):1984-1994. doi: 10.1002/cssc.201802558. Epub 2019 Mar 1.
Semiconductor photocorrosion is a major challenge for the stability of photoelectrochemical water-splitting devices. Usually, photocorrosion is studied on the basis of thermodynamic aspects, by comparing the redox potentials of water to the self-decomposition potentials of the semiconductor or analyzing the equilibrium phases at given electrolyte conditions. However, that approach does not allow for a prediction of the decomposition rate of the semiconductor or the branching ratio with the redox reaction. A kinetic model has been developed to describe detailed reaction mechanisms and investigate competition between water-splitting and photocorrosion reactions. It is observed that some thermodynamically unstable semiconductors should photocorrode in a few minutes, whereas others are expected to operate over a period of years as a result of their extremely low photocorrosion current. The photostability of the semiconductor is mainly found to depend on surface chemical properties, catalyst activity, charge carrier density, and electrolyte acidity.
半导体光腐蚀是光电化学水分解装置稳定性面临的主要挑战。通常，光腐蚀是基于热力学方面进行研究的，通过比较水的氧化还原电位与半导体的自分解电位，或者分析给定电解质条件下的平衡相。然而，这种方法无法预测半导体的分解速率或与氧化还原反应的分支比。已经开发了一种动力学模型来描述详细的反应机制，并研究水分解和光腐蚀反应之间的竞争。据观察，一些热力学上不稳定的半导体应该在几分钟内发生光腐蚀，而另一些由于其极低的光腐蚀电流，预计可以运行数年。发现半导体的光稳定性主要取决于表面化学性质、催化剂活性、载流子密度和电解质酸度。
