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

Abstract

Electroreduction of nitrate to ammonia (NO₃RR) 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 NO₃RR catalyst. Such a strategy is able to not only accelerate the reaction kinetics but also induce a self-healing feature toward the catalyst. During NO₃RR, its phase is in situ reconstructed from CuO to Cu/Cu₂O, 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 NH₃ yield rate of 105.66 mg h^–1 cm^–2 and Faradaic efficiency of 96.7%, along with excellent long-term stability at a NH₃ 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 NO₃RR catalysts.