Unveiling the Dual Role of Cobalt in Synergistic Cu–Co Electrocatalysts for Efficient Nitrate Reduction to Ammonia

The electrocatalytic nitrate reduction reaction (NO 3 RR) represents a viable solution that can not only restore the global nitrogen cycle but also provide a sustainable avenue for NH 3 synthesis. Herein a series of Cu−Co catalysts were designed and prepared using a tungstate group as the structural backbone. Experimental and theoretical investigations reveal that the incorporation of Co sites effectively modulates the electronic structure of Cu sites, thereby enhancing nitrate adsorption and deoxygenation. This modification also significantly lowers the energy barrier for subsequent hydrogenation by accelerating water dissociation while simultaneously suppressing the competing hydrogen evolution reaction. As expected, the optimal Cu 0.85 Co 0.15 WO 4 exhibits the outstanding NO 3 RR performance for NH 3 synthesis, achieving a high Faradaic efficiency of 91.61% and a yield rate of 48.56 mg h −1 mg cat. −1 at −0.8 V. Furthermore, a highly efficient zinc‐nitrate battery was developed, accomplishing the triple objectives of NH 3 synthesis, nitrate wastewater treatment, and electrical energy output.