Electroreduction of Nitrite to Ammonia over a Cobalt Single-Atom Catalyst

Electrochemical nitrite-to-ammonia reduction (NO 2 RR) holds great promise for converting harmful NO 2 – into valuable NH 3 . Herein, we develop Co single atoms dispersed on a C 3 N 4 substrate (Co 1 /C 3 N 4 ) as an efficient catalyst toward the NO 2 RR. Experimental and theoretical investigations reveal that single-atom Co sites can effectively active NO 2 – and optimize the formation energy of the key *NOH intermediate to promote the NO 2 – → NH 3 energetics. Remarkably, Co 1 /C 3 N 4 equipped in a flow cell delivers the exceptional NH 3 –Faradaic efficiency of 97.9% and NH 3 yield rate of 1080.3 μmol h –1 cm –2 at an industrial-level current density of 355 mA cm –2, along with a long-term durability of 100 h of electrolysis, showing the considerable potential for practical NH 3 electrosynthesis.