Elucidation of Electrochemically Induced but Chemically Driven Pt Dissolution.

Securing the electrochemical durability of noble metal platinum is of central importance for the successful implementation of a proton exchange membrane fuel cell (PEMFC). Pt dissolution, a major cause of PEMFC degradation, is known to be a potential-dependent transient process, but its underlying mechanism is puzzling. Herein, we elucidate a chemical Pt dissolution process that can occur in various electrocatalytic conditions. This process intensively occurs during potential perturbations with a millisecond timescale, which has yet to be seriously considered. The open circuit potential profiles identify the dominant formation of metastable Pt species at such short timescales and their simultaneous dissolution. Considering on these findings, a proof-of-concept strategy for alleviating chemical Pt dissolution is further studied by tuning electric double layer charging. These results suggest that stable Pt electrocatalysis can be achieved if rational synthetic or systematic strategies are further developed.