The critical role of potential-dependent O2 adsorption in electrochemical oxygen reduction on goldene

Abstract

The oxygen reduction reaction (ORR) is a pivotal process in many renewable energy technologies. But a comprehensive understanding of its underlying reaction mechanisms remains elusive. Herein, we select goldene as a model to investigate the potential-dependent ORR using the constant-potential method, incorporating both implicit and hybrid solvation models. Our findings reveal that the aqueous environment plays a crucial role in facilitating O₂ adsorption. Contrary to the widely accepted concept that only proton-coupled electron transfer (PCET) steps are potential-dependent, we demonstrate that the initial O₂ adsorption is also a potential-dependent electron transfer step (ETS), rather than invariant within the operative potential range. By constructing potential-dependent free energy profiles for ORR on the goldene surface, we establish the critical role of O₂ adsorption in the entire reaction pathway. Neglecting this process may result in erroneous predictions of electrocatalytic activity, as the potential-dependent nature of adsorption significantly influences subsequent reaction steps. This work underscores the necessity of accounting for the potential sensitivity of conventionally considered non-electrochemical steps for achieving more accurate and comprehensive understanding of the reaction mechanism. This approach can be readily applied to the broad investigation of other materials and reactions to accelerate the discovery of advanced materials for a range of electrochemical transformations.