Accelerated Tandem Catalysis for Industrial‐Level Nitric Oxide Electroreduction to Ammonia

Abstract

ABSTRACT State‐of‐the‐art nonprecious metal catalysts for electrocatalytic nitric oxide reduction (NORR) to NH 3 suffer from mass transfer limitation and hydrogen evolution competition at industrial current densities. Herein, we report a class of self‐supporting wheat‐shaped oxygen vacancy‐rich Co 3 O 4‐ x /Cu electrocatalyst for achieving industrial‐level nitric oxide electroreduction to NH 3 . We demonstrate a tandem mechanism wherein Co 3 O 4‐ x enables water dissociation to generate active *H and the presence of oxygen vacancies reduce the reverse spillover energy of *H migration for the NORR, while highly conductive Cu sites facilitate the adsorption and activation of *NO, and promote hydrogenation and subsequent N‐O bond cleavage, and ultimately enable NH 3 desorption. The Co 3 O 4‐ x /Cu catalyst delivers an unprecedented NH 3 yield of 938.6 ± 11.8 µmol h −1  cm −2 and Faradaic efficiency (FE) of 94.9 ± 0.4% at −1.0 V against a reversible hydrogen electrode (RHE) and maintains exceptional stability of > 350 h under industrial‐level current density of 300 mA cm −2 , outperforming previously reported catalysts. As a proof of concept, the Co 3 O 4‐ x /Cu catalyst‐based Zn‐NO battery has a record power density of 9.4 mW cm −2 and NH 3 yield of 752.1 ± 10 µg h −1  cm −2 .