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Abstract Ammonia production by electrocatalytic nitrate reduction reaction (NO 3 RR) in water streams is anticipated as a zero‐carbon route. Limited by dilute nitrate in natural sewage and the electrostatic repulsion between NO 3 − and cathode, NO 3 RR can hardly be achieved energy‐efficiently. The hydrophilic Cu@CuCoO 2 nano‐island dispersed on support can enrich NO 3 − and produce a sensitive current response, followed by electrosynthesis of ammonia through atomic hydrogen (*H) is reported. The accumulated NO 3 − can be partially converted to NO 2 − without external electric field input, confirming that the Cu@CuCoO 2 nano‐island can strongly bind NO 3 − and then trigger the reduction via dynamic evolution between Cu–Co redox sites. Through the identification of intermediates and theoretical computation. it is found that the N‐side hydrogenation of *NO is the optimal reaction step, and the formation of N─N dimer may be prevented. An NH 3 product selectivity of 93.5%, a nitrate conversion of 96.1%, and an energy consumption of 0.079 kWh g NH3 −1 is obtained in 48.9 mg‐N L −1 naturally nitrate‐polluted streams, which outperforms many works using such dilute nitrate influent. Conclusively, the electrocatalytic system provides a platform to guarantee the self‐sufficiency of dispersed ammonia production in agricultural regions.
Xue et al. (Wed,) studied this question.