Steam-Reformed Dispersive Sites with Cu0-Cu+ Interface for Electroreduction of Nitrate to Ammonia.

Electrocatalysis represents an attractive approach for nitrate recovery from wastewaters through catalytic nitrate reduction (NO3RR) to produce value-added ammonia. Although metallic copper catalysts are increasingly utilized, their nanoparticles tend to agglomerate in reactive atmospheres, degrading the catalytic performance. This study proposed a methanol steam reforming strategy to tailor metallic copper catalysts, generating dispersed sites with a unique Cu0-Cu+ interface. During the 120 h reformation process, the mean size of Cu particles decreases from 80.03 to 22.13 nm. The reformed catalyst achieves a Faraday efficiency of 87% and a NH3 production rate of 10.39 mg h-1 mgcat-1 at -0.4 V, along with remarkable long-term durability. The redispersion of coupling Cu sites enhances the adsorption and hydrogenation of key intermediates (*NO2) in NO3RR, facilitating efficient NH3 production. Furthermore, the Zn-NO3- battery with a re-Cu/C-120 cathode delivers an open-circuit voltage of 1.27 V and a power density of 8.46 mW cm-2. These results present an effective strategy for constructing dispersed active sites on metallic nanoparticles for advanced electrocatalysis.