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

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