In Situ Study of the Gas-Phase Electrolysis of Water on Platinum by NAP-XPS

摘要

Water electrolysis is critical for integrating renewable primary electricity into existing energy systems. However, for practical grid-scale application, the performance and stability of the electrolyzers must be improved. Research in materials science tries to improve the efficiency of the process through the development of an electrode with low intrinsic over-potential as well as stability against corrosion induced at the anodic potential of the oxygen evolution reaction (OER) during cyclic operation. Knowledge of the structural transformation of the electrocatalyst surface upon QER is essential to design better electrode materials. Pt is one of the most frequently used materials for polyelectrolyte membrane (PEM) fuel cells' and has been considered as a model system to study structural transformations upon polarization.In aqueous medium, lugh anodic polarization results in the dissolution of oxygen into the metallic electrode and under extreme conditions, oxygen evolution. That is, the OER occurs only after the appropriate population of oxygen species in Pt has been achieved. Pioneering work by Bockris et al. by means of in situ ellrpsometry identified the formation of a PtO2 phase before OER takes place and subsequent transition to instable PtO3 as the mechanism of OER. In contrast, ~(18)O experiments aimed to clarify the involvement of the oxide layer for the OER are contradictory.