A Wetting and Capture Strategy Overcoming Electrostatic Repulsion for Electroreduction of Nitrate to Ammonia from Low-Concentration Sewage.

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.