Efficient Electrochemical Nitrate Removal by Ordered Ultrasmall Intermetallic AuCu₃ via Enhancing Nitrate Adsorption

Developing a high-performance electrocatalyst for synthesizing ammonia from nitrate represents a promising solution for addressing wastewater pollution and achieving sustainable ammonia production. However, it remains a formidable challenge. Herein, an intermetallic AuCu₃ electrocatalyst with high-density active sites is designed and prepared for an efficient nitrate electroreduction to generate ammonia. Remarkably, the Faraday efficiency and yield rate of ammonia at -0.9 V are 97.6% and 75.9 mg h^-1 cm^-2, respectively. More importantly, after 10 cycles of testing, the removal rate of nitrate can still reach 95.2%. Electrochemical in situ Fourier transform infrared analysis indicates that AuCu₃ IM can promote the adsorption of nitrate and enhance ammonia production from nitrate. *NH₃, *NO, and *NO₂ have been proven to be active intermediates. Theoretical and experimental studies show that the Au site can provide a large amount of *H for nitrate reduction, and the Cu site is conducive to the reduction of nitrate to produce nitrogen-containing products. Meanwhile, AuCu₃ intermetallic compounds (AuCu₃ IM) can inhibit the dimerization of *H. The power density and ammonia yield of the assembled Zn-nitrate battery reached 2.17 mW cm^-2 and 71.2 mg h^-1 cm^-2, respectively.