Non-Precious Metal Diatomic Synergistic Properties Can Directly Electrocatalyze Highly Selective Conversion of Ammonia-Containing Wastewater to N₂

The treatment of high-concentration industrial ammonia-containing wastewater is energy-intensive, but direct electrocatalytic technology can not only remove nitrogen but also recover hydrogen energy stored in ammonia. However, due to the slow ammonia oxidation kinetics and the difficulty in selectively controlling the generation of nitrogen gas, developing high-activity, high-selectivity catalysts has been a key challenge. This study proposes a catalyst with dual-atom active sites that can regulate the sequential adsorption/dehydrogenation and N–N bond coupling of ammonia molecules on the dual active sites, demonstrating high catalytic activity and selectivity. Using real photovoltaic wastewater with an initial NH4+–N concentration of 3256.05 mg/L, five cycles of 150 h denitrification experiments were conducted to investigate the nitrogen removal performance and long-term stability of the dual-atom catalyst. The results showed that the N2 selectivity in all five cycles remained above 99.5%, with a H2 production rate of around 130 mL. This excellent performance can be attributed to the unique synergistic effect of the Ni–Zn dual-atom catalyst, which enhances the adsorption ability of the sites, facilitates the dehydrogenation of ammonia molecules via a dual-site pathway, and promotes the N–N bond coupling process. This study expands the feasibility of green electrochemical treatment and energy recovery for high-ammonia wastewater.