Endowing Cu-Based Oxide with a Self-Healing Feature via High-Entropy Doping toward Ampere-Level Electrochemical Nitrate Reduction to Ammonia

Electroreduction of nitrate to ammonia (NO 3 RR) is a potential route for ambient ammonia synthesis. However, the complex eight-electron transfer process makes it a great challenge to achieve high-efficiency ammonia production. Herein, a kind of Cu-based oxide with a design of high-entropy doping is presented as an efficient NO 3 RR catalyst. Such a strategy is able to not only accelerate the reaction kinetics but also induce a self-healing feature toward the catalyst. During NO 3 RR, its phase is in situ reconstructed from CuO to Cu/Cu 2 O, which quickly restores to CuO reversibly after electrolysis. As expected, ampere-level ammonia production was achieved on the proof-of-concept catalyst, with a maximized NH 3 yield rate of 105.66 mg h –1 cm –2 and Faradaic efficiency of 96.7%, along with excellent long-term stability at a NH 3 partial current density over 1.2 A cm –2 . We believe that the high-entropy doping strategy offers an efficient approach for the future design of NO 3 RR catalysts.