First principles study on electronic properties and oxygen evolution mechanism of 2D bimetallic N-doped graphene

Currently, the oxygen evolution reaction (OER) is constrained by complex four-electron transport, thus it is difficult to understand the catalytic mechanism. In this work, the electronic properties and catalytic performance of M₁M₂/NC (M = Mn, Fe, Co, Ni, Cu and Zn, random combination in pairs) is studied by density functional theory, the calculated results show that the overpotential of FeCu/NC is 0.88 V, which is used as the optimal catalyst to further study the OER reaction mechanism. Combined with the volcano map and the d-band center position, the low overpotential of FeCu/NC is because it has a more suitable position of d-band center -1.806 eV than other materials. Moreover, the calculation results show that the density of states (DOS) of iron-containing materials is stronger than that of other materials near the Fermi level, which can promote the catalytic reaction. In addition, O∗OH and O∗H, O∗H and O∗ linearly related theoretical equations are proposed, respectively. Furthermore, the analysis of the catalytic mechanism shows that the formation of the catalytic rate-determining step is affected by the movement of the d-band center, the distance of the transition state adsorption and the electric field.