Homogeneously Mixed Cu–Co Bimetallic Catalyst Derived from Hydroxy Double Salt for Industrial-Level High-Rate Nitrate-to-Ammonia Electrosynthesis
Wonsik Jang, Dongrak Oh, Jin‐Young Lee, Jongkyoung Kim, Jesse E. Matthews, Hyoseok Kim, Sang‐Won Lee, Seunghyun Lee, Yi Xu, Je Min Yu, Seon Woo Hwang, Thomas F. Jaramillo, Ji‐Wook Jang, Seungho Cho
Abstract
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.