Enhanced nitrate to ammonia activity by Fe addition in nanoporous CuCoFe with multi-active sites

The electrochemical reduction of nitrate ions to valuable ammonia enables the recovery of the nitrate pollutants from industrial wastewater, thereby synchronously balancing the nitrogen cycle and achieving NH₃ production. Herein, we synthesize a nanoporous CuCoFe by a chemical dealloying method for efficient nitrate reduction reaction (NO₃RR). By screening, we find that the addition of Fe can further enhance the performance of the well-reported CuCo in terms of NH₃ Faradaic efficiency (FE), and NH₃ partial current density. The catalyst achieves a high NH₃ yield rate of 935.8 and 1192.2 μmol h⁻¹ cm⁻², with corresponding FE values of 98.1% and 92.2% at −0.5 and −0.7 V vs RHE, respectively. This superior performance can be attributed to the effect of enhanced intermediates adsorption and strengthened water activation on Fe sites, which also decreases the energy barrier for the rate-determining step from NO₂⁻ to NH₃, i.e., *NH₃ desorption. Thanks to the enhanced electrocatalytic activity, we assemble a Zn-NO₃^- battery, which delivers a high open-circuit voltage of 1.309 V and a maximum output power density of 10.88 mW cm⁻², demonstrating the potential application value.