Homogeneously Mixed Cu-Co Bimetallic Catalyst Derived from Hydroxy Double Salt for Industrial-Level High-Rate Nitrate-to-Ammonia Electrosynthesis.

Electrocatalytic nitrate reduction reaction (NO 3 RR) presents an innovative approach for sustainable NH 3 production. However, selective NH 3 production is hindered by the multiple intermediates involved in the NO 3 RR process and the competitive hydrogen evolution reaction. Hence, the development of highly efficient NO 3 RR catalysts is paramount. Herein, we report highly efficient bimetallic catalysts derived from hydroxy double salt (HDS). Under NO 3 RR conditions, Cu 1 Co 1 -HDS undergoes in situ reconstruction, forming nanocomposites of homogeneously distributed metallic Cu 0 and Co(OH) 2 . Reconstruction-induced Cu 0 rapidly converts NO 3 - to NO 2 - , which is further hydrogenated to NH 3 by Co(OH) 2 . Homogeneously mixed Cu and Co species maximize this synergistic effect, achieving outstanding NO 3 RR performance including the highest NH 3 yield rate (4.625 mmol h -1 cm -2 ) reported for powder-type NO 3 RR catalysts. Integration of Cu 1 Co 1 -HDS with a commercial Si solar cell attained 4.53% solar-to-ammonia efficiency from industrial wastewater-level concentrations of NO 3 - (2000 ppm), demonstrating practical application potential for solar-driven NH 3 production. This study provides a strategy for enhancing the NH 3 yield rate by optimizing the compositions and distributions of Cu and Co.