Optimal Solution for Modeling Electrocatalysis on Two-Dimensional Single-Atom Catalysts with Grand Canonical DFT

Single-atom catalysts (SACs) have received great attention due to their exceptionally high metal atom utilization and outstanding catalytic activity. In this work, the potential-dependent reaction kinetics of the hydrogen evolution reaction on single-atom catalysts have been investigated. The appearance of the “potential shift” effect in canonical DFT within the charge-neutral model (CNM) and the “charge shift” effect in grand canonical DFT within the constant-potential model (CPM), caused by the difference in the strength of the substrate–adsorbent interaction, is schematically illustrated. The origins of the abnormal reaction and activation energy differences between CNM and CPM on SACs have been clearly identified. It is found that considerable “potential shift” effects or “charge shift” effects are inevitable on two-dimensional SACs due to the overestimated adsorbate–substrate interactions, which lead to unreasonable energy profiles. Here, we propose a corrective method for introducing a conductive substrate to construct supported SAC electrodes. The modified SAC models can remarkably reduce the “charge shift” effect for constant-potential energy calculations, thus providing a more accurate consideration of the electrode potential effect. This work presents an improved theoretical model for constant-potential energy simulations of SACs.