Single-Atom Metal Anchored Penta-Graphene for Highly Efficient and Selective Electroreduction of Nitrogen into Ammonia

The Haber-Bosch (H–B) process might take place by electrochemical nitrogen reduction reaction (NRR) to generate ammonia if appropriate electrocatalysts can be matured. We methodically investigate the reaction mechanisms of the electrochemical NRR on a single-atom metal anchored penta-graphene (TM-PG, TM = Sc–Hg) by density functional theory computations. Particularly, 14 TM-PGs including Ti-, V-, Cr-, Co-, Cu-, Nb-, Mo-, Tc-, Ru-, Rh-, W-, Re-, Os-, and Ir-PG are selected benefiting from their high activity for the NRR (limiting potential ≤ −0.98). We also studied the competitive hydrogen evolution reaction (HER) on the TM-PGs. Among them, 12 TM-PG (Ti-, V-, Cr-, Co-, Mo-, Tc-, Ru-, Rh-, W-, Re-, Os-, and Ir-PG) catalysts suppressing the competitive HER with high selectivity (Faradaic efficiency of ∼100%) are obtained. The Cr-, Mo-, Tc-, Re-, Os-, and Ir-PG will have superior performance for the NRR with a low limiting potential less than 0.6 V. Partial density of states (PDOS) and Bader charge analysis shed light on the origin of NRR catalytic activity of TM-PG. This study extends the penta-carbon family as promising electrocatalysts for the NRR as well as provides a modus for the practical design of NRR catalysts under ambient conditions.