Cu@g-C3N4: An Efficient Single-Atom Electrocatalyst for NO Electrochemical Reduction with Suppressed Hydrogen Evolution

Nitric oxide electroreduction reaction (NOER) is one of the most attractive routes for ammonia synthesis and pollutant treatment. However, the current research efforts toward the NOER mainly focus on metal surface catalysts, while low-cost and high-efficiency single-atom catalysts (SACs) are rarely explored. Herein, using first-principles computations, we systematically investigate the NOER performance of a series of transition-metal-atom-decorated graphitic carbon nitride monolayer (g-C3N4) and identify single Cu-atomdecorated g-C3N4 (Cu@g-C3N4) as the most promising SAC candidate for the NOER. Our results indicate that Cupg-C3N4 harbors excellent catalytic activity for the NOER with a quite low limiting potential of 0.371 V and, interestingly, is promising to be synthesized due to extremely high stability. Most importantly, Cu@g-C3N4 can efficiently suppress the competing hydrogen evolution reaction, in favor of achieving high Faradaic efficiency. Our work provides a promising SAC candidate for the NOER to resolve environmental pollution and sustainable ammonia production.