Density Functional Theory Studies on Boron-Modified Graphene Edges for Electroreduction of Nitrogen

Electrocatalytic nitrogen reduction reaction (ENRR) under ambient conditions is one of the most promising alternatives to the traditional energy-intensive Haber–Bosch method to alleviate the energy crisis and environmental concerns. However, most current ENRR processes suffer from low catalytic activity resulting in low Faradaic efficiency and NH3 yields. High-efficiency and low-cost nanoscale electrocatalysts are urgently required. Herein, six metal-free single-boron-modified graphene edges were designed at the atom level and density functional theory calculations were used to evaluate the structural and NRR catalytic properties. Our results demonstrated that graphene edges could effectively stabilize isolated boron atoms, and the boron atom in the zigzag edge of graphene (B-ZZ-S) exhibited the best performance. It had the smallest free energy change of 0.85 eV via the distal mechanism which was superior to a benchmark metal catalyst flat Ru(0001) (1.08 eV). We believe that it is the charge variation between NRR intermediates and designed boron-based catalysts that gives rise to the high NRR activity which can be well described by the binding strength of *N species.