Kinetic competition between water splitting and photocorrosion reactions in photoelectrochemical devices

Semiconductor photocorrosion is a major challenge for the stability of photoelectrochemical water splitting devices. Usually, photocorrosion is studied on the basis of thermodynamic aspects, 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 semiconductor’s decomposition rate or the branching ratio with the redox reaction. We developed a kinetic model to describe the detailed reaction mechanisms and investigated the competition between water splitting and photocorrosion reactions. We observed that some thermodynamically unstable semiconductors should photocorrode in a few minutes while others are expected to operate over a period of years given by their extremely low photocorrosion current. The semiconductor’s photostability is found to mainly depend on surface chemical properties, catalyst activity, charge carrier density, and electrolyte acidity.


Published in:
ChemSusChem
Year:
2019
Laboratories:




 Record created 2019-01-14, last modified 2019-06-19

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