Revealing Elusive Intermediates of Platinum Cathodic Corrosion through DFT Simulations

Cathodic corrosion of metals discovered more than 120 yearsago remains a poorly understood electrochemical process. It is believed thatthe corrosion intermediates formed during cathodic polarization areextremely short-lived species because of their high reactivity. Togetherwith the concurrent vigorous hydrogen evolution, this makes it challengingto investigate the reaction mechanism and detect the intermediatesexperimentally. From a computational standpoint, the process also presentsa serious challenge as it occurs at rather low negative potentials inconcentrated alkaline solutions. Here, we use density-functional-theorycalculations to elucidate the identity of reaction intermediates and theirreactivity at the Pt(111)/electrolyte interface. By controlling the electrodepotential in an experimentally relevant region through constant Fermi-level molecular dynamics, we reveal the formation of alkalication-stabilized Pt hydrides as intermediates of cathodic corrosion. The results also suggest that the found Pt anions could dischargeat the interface to produce H2by reacting with either surface-bound hydrogen species or solution water molecules