Cu/C composite electrode for efficient reduction of nitrate in wastewater

Nitrate pollution in aquatic environments, primarily caused by the excessive use of nitrogen fertilizers in agriculture and the unregulated discharge of nitrogen-containing compounds from industrial activities, has become a global environmental challenge. Electrochemical technologies offer a promising solution due to their controllability, environmental compatibility, and avoidance of secondary pollution. In this study, a Cu/C composite electrode was fabricated, and the effects of various preparation parameters on its electrochemical properties and nitrate reduction performance were systematically investigated. The optimized Cu/C electrode, supported on a carbon paper substrate, exhibited superior performance with a nitrate removal efficiency of 59.15 % in simulated wastewater and 86.74 % in real wastewater. Mechanistic analysis indicates that nitrate is first reduced to intermediate nitrogen species (NO₂⁻, NHₓ) on Cu active sites and subsequently converted into NH₄⁺ or N₂, while Cl⁻ plays a dual role by enhancing interfacial ion transport and generating ClO⁻ at the Pt anode to further oxidize NH₄⁺ to N₂. Compared with previously reported Cu/C systems, this study highlights the synergistic regulation of the carbon substrate and Cl⁻, which significantly improves both selectivity and stability. These findings demonstrate that Cu/C electrodes provide an efficient, stable, and environmentally friendly electrochemical strategy for treating nitrate-contaminated wastewater, highlighting strong potential for practical applications.