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.