Low-nitrite generation Cu–Co/Ti cathode materials for electrochemical nitrate reduction

In order to reduce by-product nitrite, a more toxic compound than nitrate, and increase high value-added products ammonia in the electrochemical reduction nitrate process, the novel Cu–Co/Ti cathode material was applied in this process. In this paper, the electrochemical process was carried out in a single compartment electrolytic cell, and with Cu–Co/Ti electrode as cathode, identifying the effects of current density, pH, electrolytes in the nitrate reduction, and the distribution of products. The Cu–Co/Ti cathode exhibited 94.65% NO 3 − -N (nitrate–N) removal, 0.18% NO 2 − -N (nitrite-N) generation, and 40.86% NH 4 − -N (ammonia-N) generation with the assistance of Na 2 SO 4 electrolyte in 6 h at 10 mA cm −2 and pH 6. Compared with the Cu/Ti cathode, the higher nitrate removal ratio and lower nitrite generation ratio were obtained on the Cu–Co/Ti cathode. The excellent performance of Cu–Co/Ti cathode is ascribed to the synergy of Cu and Co, which couples the facilitation of nitrate conversion to nitrite and the acceleration of nitrite reduction on the Cu–Co/Ti cathode. The LSV curves showed that nitrate and nitrite might undergo indirect and direct reduction reactions on Cu–Co/Ti cathode. The possible pathways of nitrate reduction on the Cu–Co/Ti cathodes were proposed. These results highlight the viability of using the Cu–Co/Ti cathode developed at this work for the nitrate removal from contaminated waters. This study achieved low-nitrite generation by Cu–Co/Ti cathode during electrochemical nitrate reduction.