Cobalt Nanoparticles Encapsulated in N-Doped Carbon Nanotubes Assembled on Carbon Cloth for Efficient Electroreduction of Nitrite to Ammonia

Electrochemical nitrite (NO2–) reduction provides an alternative pathway for both sustainable ammonia (NH3) synthesis and reutilization of NO2– pollutants, but this process requires high activity and selective catalysts. In this work, cobalt nanoparticles encapsulated in N-doped carbon nanotubes supported on carbon cloth (Co@NCNT/CC) as a low-cost electrocatalyst can efficiently catalyze NO2–-to-NH3 conversion. Such Co@NCNT/CC shows exceptional electrocatalytic performance, achieving a maximum NH3 Faradaic efficiency of 94.9% with an NH3 yield of 365.1 μmol h–1 cm–2 at −0.3 V. Remarkably, the assembled Zn–NO2– battery with the Co@NCNT/CC cathode exhibits a peak power density of 4.4 mW cm–2 and a satisfactory NH3 yield of 141.5 μmol h–1 cm–2.