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

Spinel oxides, especially Co 3 O 4 , have been considered as ideal electrocatalysts for electrocatalytic nitrate reduction reaction (e-NO 3 RR). However, their application in e-NO 3 RR is still limited because of relatively low activity and selectivity under high potential. Herein, we present that the incorporation of manganese (Mn) into the Co 3 O 4 lattice can achieve the high activity and selectivity in e-NO 3 RR. The Mn-incorporated Co 3 O 4 nanotubes show a remarkable e-NO 3 RR 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-NO 3 RR. We believe that the findings provide an insightful guidance to engineer the spinel oxides for enhanced performance towards ideal products. [Display omitted] • Mn-incorporated Co 3 O 4 nanotubes show the highest ammonia yield rate among transition-metal based oxides. • Mn-incorporated Co 3 O 4 nanotubes show high selectivity and stability of e-NO 3 RR. • the Mn ion only partially replaces Co in the CoO 6 octahedrons of spinel Co 3 O 4. • The synergistically catalytic mechanism for Mn-incorporated Co 3 O 4 was surveyed. [ABSTRACT FROM AUTHOR]