One-step synthesis of Cu(OH)2-Cu/Ni foam cathode for electrochemical reduction of nitrate

Nitrate (NO3−) pollution in natural water is severe and brings serious environmental and human health problems. With the rise of electrocatalytic NO3− reduction, highly reactive and selective electrodes are essential for the electrochemical reduction of NO3−. In this study, a one-step hydrothermal method was used to load Cu and Cu(OH)2 on Ni foam (NF) (Cu(OH)2-Cu/NF) as a cathode. The system’s unique design includes: Cu and Ni can promote the reduction of NO3− and the generation of active hydrogen atom (H*) as a reducing agent. Then, Cu(OH)2 is beneficial to NO2− adsorption and promotes the reduction of NO2− intermediate. Finally, NH4+ is oxidized to N2 by reactive chlorine generated at the anode. The Cu(OH)2-Cu/NF electrode exhibits a 91.5 % conversion of NO3−-N in 90 min, which is 44 times higher than that of NF. Under 2000 mg/L Cl−, NH4+ finally oxidizes to N2 within 360 min, and N2 selectivity is 95.60 %. In addition, the Cu(OH)2-Cu/NF electrode maintained an excellent electrochemical performance after 20 cycles. This study provided a new idea for designing efficient, stable, and inexpensive NO3− reduction electrodes.