Electrocatalytic Reduction of Nitrate CoO/Ti Cathode Prepared by Electrodeposition Paired With IrO-RuO Anode.

Nitrate pollution is already a global problem, and the electrocatalytic reduction of nitrate is a promising technology for the remediation of wastewater and polluted water bodies. In this work, CoO/Ti electrodes were prepared by electrodeposition for the electrocatalytic reduction of nitrate. The morphology, chemical, and crystal structures of CoO/Ti and its catalytic activity were investigated. Then, the electrocatalytic nitrate reduction performance of CoO/Ti as the cathode was evaluated by monitoring the removal efficiencies of nitrate (NO -N) and total nitrogen (TN), generation of reduction products, current efficiency (CE), and energy consumption (EC) at different operating conditions. Under the catalysis of CoO/Ti, NO was reduced to N and NH , while no NO was produced. After the introduction of chloride ions and IrO-RuO/Ti as the anode, NH was selectively oxidized to N. The removal efficiencies of NO -N (at 100 mg/L) and TN after 2 h were 91.12% and 60.25%, respectively (pH 7.0; Cl concentration, 2000 mg/L; current density, 15 mA/cm). After 4 h of operation, NO -N and TN were completely removed. However, considering the EC and CE, a 2-h reaction was the most appropriate. The EC and CE were 0.10 kWh/g NO N and 40.3%, respectively, and electrocatalytic performance was maintained after 10 consecutive reduction cycles (2 h each). The cathode CoO/Ti, which is prepared by electrodeposition, can effectively remove NO -N, with low EC and high CE.