Ce-Doping Enhances the Electrocatalytic Oxidation of High-Concentration Ammonia Nitrogen Wastewater by NiCu Oxide

Nickel-copper-cerium mixed metal oxide electrode (Ni-Cu-Ce 0.05 -O) was synthesized on nickel mesh substrates using a hydrothermal-calcination process with cerium as the dopant. Comprehensive characterization revealed that optimal Ce doping significantly increases the specific surface area while effectively modulating the electronic structure of Ni and Cu, though excessive doping promotes Ce aggregation and CeO 2 phase formation. Electrochemical tests demonstrated that the Ni-Cu-Ce 0.05 -O electrode exhibits superior performance compared to the NiCu mixed metal oxide electrode (Ni-Cu-O), with the net ammonia oxidation current density at 1.60 V reaching 136.5 mA cm −2 . In simulated wastewater treatment, 88.0% ammonia removal efficiency with 80.1% nitrogen selectivity was achieved after 6-hour electrolysis for the Ni-Cu-Ce 0.05 -O electrode. For real wastewater (pH = 13, initial NH 4 + -N = 915 mg l −1 ), 58.9% removal efficiency and remarkably 94.2% nitrogen selectivity were obtained after 15 h treatment. This study demonstrates that Ce-doped NiCu mixed metal oxide electrodes offer superior denitrification performance and nitrogen selectivity, presenting a promising solution for efficient and environmentally friendly high-concentration ammonia nitrogen industrial wastewater remediation.