Electrocatalytic removal of nitrate by non-noble Fe₃C/Cu: Property, mechanism, and practical water treatment...

The application of electrocatalytic technology in nitrate (NO₃^-) removal is hindered by the low total nitrogen (TN) removal efficiency during the reaction. In this study, a non-noble Fe₃C/Cu@CC cathode, prepared by in-situ growth of Fe₃C on carbon cloth followed by electrodeposition of Cu nanoparticles, was proposed for electrocatalytic reduction of NO₃^-. Electrochemical tests showed that Fe₃C/Cu@CC possessed good NO₃^- reduction property and N₂ selectivity, especially under neutral pH condition. 68.35 % of NO₃^- was removed and 60.40 % of N₂ selectivity was achieved in simulated wastewater at -1.5 V vs. SCE, in 5 h. For actual coking wastewater treatment, Fe₃C/Cu@CC removed 56.10 % of NO₃^- and 56.33 % of total nitrogen (TN), with N₂ selectivity as high as 100%. Mechanism studies via UPS, EPR, DEMS and DFT calculations revealed the redistribution of electron density at the Fe-Cu interface enhanced the formation of *H and decreased the desorption energy barrier of N₂ at the interface, further improving the selectivity of N₂. The material characterization and cyclic test proved the good stability of Fe₃C/Cu@CC electrode in both simulated wastewater and actual coking wastewater. This work provided insights into efficient non-noble metal catalyst design for practical NO₃^- wastewater treatment.