Cu and Zn metal particles modified nanocathode based electrocatalytic nitrate reduction: Effective, selective and mechanism

Nitrate contamination of water resources not only endangers ecological environment, but also poses a threat to human health. Electrochemical removal of nitrate is limited by poor electrode efficiency and high levels of byproducts. Herein, Cu and Zn nanoparticles were loaded onto the surface of TiO2 nanoelectrodes by electrodeposition to improve the electrochemical activity of the electrodes. The fabricated Cu/TiO2 and Cu/Zn/TiO2 nanoelectrodes achieved nitrate removal efficiencies of 83.5 % and 93.6 %, respectively, indicating a significant improvement in nitrate removal efficiency. The physicochemical and electrochemical characteristics of the Cu/TiO2 and Cu/Zn/TiO2 electrode revealed that the TiO2 nanotube structure formed on the electrode surface increased the specific surface area of the electrode, while the uniformly attached Cu and Zn nanoparticles augmented the active sites on the electrode surface. Additionally, the loaded Zn nanoparticles enhanced the conversion of NO2-N to N-2, effectively suppressing byproducts production. The synergistic effect of TiO2 nanotubes with Cu and Zn nanoparticles made it possible to completely electrochemical remove nitrate. Under the condition of 0.5 g/L NaCl as the electrolyte, these two electrochemical systems can achieve cathodic reduction of NO3-N and effectively inhibit the formation of NH4+-N and NO2--N, thereby achieving the goal of harmless removal of NO3-N. This work provides theoretical and technical support for efficient and clean removal of nitrate from environmental water bodies by electrochemistry.