Single Faceted Two-Dimensional Mo 2 C Electrocatalyst for Highly Efficient Nitrogen Fixation

Electrocatalytic reduction of N 2 to NH 3 under an ambient atmosphere is highly desirable and extremely critical for energy-efficient nitrogen utilization. Inspired by the natural MoFe protein-based enzyme, the nitrogenase, we exploited this electrochemical process with a unique two-dimensional catalyst, namely, molybdenum carbide (Mo 2 C). The catalyst is synthesized through a chemical vapor deposition method, with a highly orientated (200) facet of the α-Mo 2 C phase. A remarkable Faradaic efficiency as high as 40.2% has been achieved on the (200) faceted α-Mo 2 C during the nitrogen reduction reaction (NRR). Density functional theory calculations confirm that rate-determining steps *NNH 2 → *NNH 3 and *NH → *NH 2 experience a low energy barrier on the (200) surface following the proton–electron coupled, distal associated mechanism. To protect Mo from leaching during the NRR process, we also grew layers of graphene on top of Mo 2 C, forming a chemically enduring two-dimensional heterostructured electrode.