Grand-Canonical DFT Study of Potential-Induced Charge Redistribution at the Metal/Graphene/Electrolyte Interface

Metal/graphene heterostructures are of great interest for use in electrocatalysis, electrochemical biosensors and graphene electrografting, making it important to understand the charge redistribution features at the metal/graphene/electrolyte interface to explain and predict their electrochemical properties. In this work, using grand-canonical DFT, the charge distribution in few-layer graphene supported on Au and Pt substrates is obtained as a function of the electrode potential and the number of graphene layers. It is shown that graphene coating on the metal surface shifts the potential of zero charge towards more negative values. A phenomenological model for describing charge distribution in the studied systems is proposed and parameterized based on DFT calculations. It can be used as a charge model for the force field intended for MD simulation of electrolytes near the electrified metal/graphene heterostructures at a fixed potential relative to the standard hydrogen electrode. The results can be used for explaining, predicting and optimizing electrochemical catalysts and biosensors based on the metal/graphene heterostructures.