Efficient electroreduction of nitrate via enriched active phases on copper-cobalt oxides
Ling Fang, Sha Wang, Shun Lu, Fengjun Yin, Yujie Dai, Lin Chang, Hong Liu
Abstract
Electrochemical conversion of nitrate (NO 3 − ) to ammonia (NH 3 ) can target two birds with one stone well, in NO 3 − -containing sewage remediation and sustainable NH 3 production. However, single metal-based catalysts are difficult to drive high-efficient NO 3 − removal due to the multi-electron transfer steps. Herein, we present a tandem catalyst with simple structure, Cu-Co binary metal oxides (Cu-Co-O), by engineering intermediate phases as catalytic active species for NO 3 − conversion. Electrochemical evaluation, X-ray photoelectron spectroscopy , and in situ Raman spectra together suggest that the newly-generated Cu-based phases was prone to NO 3 − to NO 2 − conversion, then NO 2 − was reduced to NH 3 on Co-based species. At an applied potential of −1.1 V vs . saturated calomel electrode, the Cu-Co-O catalyst achieved NO 3 − -N removal of 90% and NH 3 faradaic efficiency of 81% for 120 min in 100 mL of 50 mg/L NO 3 − -N, consuming only 0.69 kWh/mol in a two-electrode system. This study provides a facile and efficient engineering strategy for developing high-performance catalysts for electrocatalytic nitrate conversion.