Mo decoration on graphene edge for nitrogen fixation: A computational investigation

Highlights: • The graphene edge with Mo decoration exhibits excellent NRR activity. • The edge fluorination significantly boosts the NRR selectivity. • The edge chemistry influences the electron distribution. Cost-effective carbon-based catalysts are promising for electrochemical ammonia synthesis. In the work, the nitrogen reduction reaction (NRR) performances of the single transition metal atom anchored zigzag graphene nanoribbon with H/F termination, termed as TM-G/H and TM-G/F, are systematically investigated via density functional theory calculations wherein V, Fe and Mo are considered among the various TM elements. The N₂-to-NH₃ conversions are conducted via the distal mechanism under the onset potentials of 0.55 and 0.42 V for Mo-G/H and Mo-G/F, respectively. More interestingly, the edge fluorination suppresses the competing hydrogen reduction reaction in comparison with the hydrogenation counterpart, boosting the NRR efficiency. The electronic analysis elucidates that the edge termination alters the binding strength of Mo anchoring and thereby modifies its affinity toward the NRR intermediates. In this regard, the activity improvement stems from the edge fluorination in combination with the Mo dopant. Beyond element-screening, our finding provides a rational strategy of edge engineering to design carbon-based electrocatalysis.