Electrocatalytic reduction of nitrate to ammonia on low-cost manganese-incorporated Co3O4 nanotubes

Spinel oxides, especially Co3O4, have been considered as ideal electrocatalysts for electrocatalytic nitrate reduction reaction (e-NO3RR). However, their application in e-NO3RR is still limited because of relatively low activity and selectivity under high potential. Herein, we present that the incorporation of manganese (Mn) into the Co3O4 lattice can achieve the high activity and selectivity in e-NO3RR. The Mn-incorporated Co3O4 nanotubes show a remarkable e-NO3RR activity with a high ammonia yield rate of 35 mg h−1 cm−2 and excellent selectivity with a Faraday efficiency for ammonia up to 99.5% in neutral media, which are much better than those of transition-metal oxides. Our calculations further show that the replacement of Co by Mn can tune the adsorption behavior of intermediates, and thus reduces the limiting potential of e-NO3RR. We believe that the findings provide an insightful guidance to engineer the spinel oxides for enhanced performance towards ideal products.