Boron-Doped Graphene for Electrocatalytic N-2 Reduction

Electrochemical N-2 reduction in aqueous solutions at ambient conditions is extremely challenging and requires rational design of electrocatalytic centers. We demonstrate a boron-doped graphene as an efficient metal-free N-2 reduction electrocatalyst. Boron doping in the graphene framework leads to redistribution of electron density, where the electron-deficient boron sites provide enhanced binding capability to N-2 molecules. Density functional theory calculations reveal the catalytic activities of different boron-doped carbon structures, in which the BC3 structure enables the lowest energy barrier for N-2 electroreduction to NH3. At a doping level of 6.2%, the boron-doped graphene achieves a NH3 production rate of 9.8 mu g.hr(-1).cm(-2) and one of the highest reported faradic efficiencies of 10.8% at -0.5 V versus reversible hydrogen electrode in aqueous solutions at ambient conditions. This work suggests the strong potential of atomic-scale design for efficient electrocatalysts for N-2 reduction.