The synergistic effect of Ni and WO2 effectively boosts the electrochemical reduction of nitrite to ammonia

Abstract

Electrocatalytic nitrite (NO₂⁻) reduction is a promising technology with significant potential applications. Simultaneously producing high-value-added ammonia (NH₃) while eliminating NO₂⁻ pollution is important in environmental protection and rebalancing the earth's nitrogen cycle. However, the efficiency of this process is sluggish, and the catalyst's performance is of paramount importance. Herein, we construct a heterostructure with Ni nanoparticles deposited on the WO₂ polyhedron self-supported Ni foam (Ni@WO₂/NF). The synergistic effect of WO₂ and Ni improves the reaction rate. Ni facilitates the decomposition of H₂O to produce *H, while WO₂ primarily engages in the hydrogenation of NO₂⁻, which significantly enhances the catalytic performance. At a low voltage of 0.1 M NaOH solution (−0.4 V vs. RHE), the faradaic efficiency (FE) reaches as high as 94.6%, with a corresponding yield of 17 959.3 μg h⁻¹ cm⁻², exceeding that of most NO₂⁻RR catalysts. In addition, the peak power density of the Zn–NO₂⁻ battery prepared based on Ni@WO₂/NF is as high as 9.53 mW cm⁻².