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

A wetting and capture strategy is proposed to overcome the intrinsic electrostatic repulsion between cathode and NO3− anions. And nanoisland-like Cu@CuCoO2 as the active phase of Cu ─Co cathode can sense low-concentration NO3− with high sensitivity and reduce NO3− to ammonia via energy-efficient atomic hydrogen pathway. AbstractAmmonia production by electrocatalytic nitrate reduction reaction (NO3RR) in water streams is anticipated as a zero-carbon route. Limited by dilute nitrate in natural sewage and the electrostatic repulsion between NO3− and cathode, NO3RR can hardly be achieved energy-efficiently. The hydrophilic Cu@CuCoO2 nano-island dispersed on support can enrich NO3− and produce a sensitive current response, followed by electrosynthesis of ammonia through atomic hydrogen (*H) is reported. The accumulated NO3− can be partially converted to NO2− without external electric field input, confirming that the Cu@CuCoO2 nano-island can strongly bind NO3− 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 NH3 product selectivity of 93.5%, a nitrate conversion of 96.1%, and an energy consumption of 0.079  kWh gNH3−1 is obtained in 48.9  mg-N L−1 naturally nitrate-polluted streams, which outperforms many works using suc...
Source: Small - Category: Nanotechnology Authors: Tags: Research Article Source Type: research