Self-supported CoWO4 nanoarrays enhance the electrochemical reduction of nitrite to ammonia

Abstract

The electrochemical reduction of nitrite (NO₂⁻RR) is a novel and effective approach to achieving efficient NH₃ electrosynthesis and wastewater purification, but the development of catalysts with high performance remains a challenge. In this study, we discovered that CoWO₄ nanosheets grown on nickel foam (CoWO₄/NF) exhibit excellent NO₂⁻RR performance. In a neutral solution containing 0.1 M NO₂⁻, CoWO₄/NF showed a high NH₃ yield of 18.856 mg h⁻¹ cm⁻² and a faradaic efficiency up to 95.2% at an optimum voltage of −0.7 V. Furthermore, the Zn–NO₂⁻ battery featuring CoWO₄/NF as the cathode demonstrates a power density reaching 7.6 mW cm⁻² and an impressive NH₃ production rate of 2.855 mg h⁻¹ cm⁻².