A Synergistic effect on the atomic cluster M4 supported on MN4-graphene (M = Fe, Ni) for the hydrogen evolution reaction

Abstract

The development of stable and efficient non-noble metal catalysts for the hydrogen evolution reaction (HER) can greatly promote the utilization of hydrogen energy. Herein, we investigated four potential model catalysts of the atomic cluster M₄ supported on MN₄-graphene substrates (M = Fe, Ni) from first-principles, i.e., Fe₄@FeN₄-Gr, Fe₄@NiN₄-Gr, Ni₄@FeN₄-Gr and Ni₄@NiN₄-Gr, respectively. Using density functional theory (DFT) calculations, the synergistic effect enhances the stability and HER activity of these supported M₄@MN₄-Gr. It is found that the Gibbs free energy of hydrogen adsorption (ΔG_H*) of Ni₄@FeN₄-Gr is only −0.168 eV with the best exchange current. We further explored the pH effect on the HER performance and determined the ideal pH range of these potential model catalysts. Four model catalysts can follow the Volmer–Tafel pathway if considering the implicit solvation effect. These results provide an effective guidance for the rational design of electro-catalysts.