A core-shell copper oxides-cobalt oxides heterostructure nanowire arrays for nitrate reduction to ammonia with high yield rate

Electrochemical nitrate reduction to ammonia (NRA) can realize the green synthesis of ammonia (NH 3 ) at ambient conditions, and also remove nitrate contamination in water. However, the current catalysts for NRA still face relatively low NH 3 yield rate and poor stability. We present here a core–shell heterostructure comprising cobalt oxide anchored on copper oxide nanowire arrays (CuO NWAs@Co 3 O 4 ) for efficient NRA. The CuO NWAs@Co 3 O 4 demonstrates significantly enhanced NRA performance in alkaline media in comparison with plain CuO NWAs and Co 3 O 4 flocs. Especially, at −0.23 V vs. RHE, NH 3 yield rate of the CuO NWAs@Co 3 O 4 reaches 1.915 mmol h −1 cm −2 , much higher than those of CuO NWAs (1.472 mmol h −1 cm −2 ), Co 3 O 4 flocs (1.222 mmol h −1 cm −2 ) and recent reported Cu-based catalysts. It is proposed that the synergetic effects of the heterostructure combing atom hydrogen adsorption and nitrate reduction lead to the enhanced NRA performance. • A core–shell heterostructure with high NRA activity is designed. • It delivers a Faradaic efficiency of 99.17% and NH 3 yield rate of 1.915 mmol h −1 cm −2 . • The performance is higher than the control samples and many other NRA catalysts. • The enhanced activity is attributed to the synergistic active phase and improved atom hydrogen adsorption. • It provides a promising catalyst for green synthesis of ammonia.