Highly selective electrochemical reduction of nitrite to ammonia over CuWO4 nanoparticles

Abstract

The electrochemical nitrite reduction reaction (NO₂⁻RR) represents a promising and sustainable strategy for NO₂⁻ removal whilst simultaneously producing high-value-added ammonia (NH₃). In this study, CuWO₄ nanoparticles exhibited good NO₂⁻RR performance for NH₃ production, achieving an NH₃ production rate of 27.46 mg h⁻¹ cm⁻² and a faradaic efficiency of 95.09%, while demonstrating excellent cycling stability at −1.0 V vs. RHE. Notably, the assembled Zn–NO₂⁻ battery delivered a high-power density of 7.6 mW cm⁻² while simultaneously yielding a substantial NH₃ production rate of 2.52 mg h⁻¹ cm⁻². Density functional theory (DFT) calculations indicate that CuWO₄ catalyzes the reaction from *NO₂ to *NO₂H, which constitutes the rate-determining step in NH₃ synthesis.