Dual-Site Activation for Efficient Acidic CO Electroreduction at Industrial-Level Current Densities.

Electroreduction of CO to formic acid in acidic media offers a promising approach for value-added CO utilization. However, achieving high selectivity for formic acid in acidic electrolytes remains challenging due to the competitive hydrogen evolution reaction (HER), particularly at industrially relevant current densities. Herein, a charge redistribution modulation strategy is demonstrated by constructing the CuS /SnS Mott-Schottky catalyst to enhance formic acid selectivity. Experiments and calculation results reveal the broadening of Sn orbitals and reduced orbital symmetry of Sn orbitals contribute to enhanced CO adsorption, while the modulated Cu sites with a stronger Lewis acid character stabilize OCHO intermediates more effectively. This enables dual-site activation for efficient CO electroreduction into formic acid synthesis. Consequently, the optimized CuS/SnS catalysts achieve a maximum formic acid Faradaic efficiency (FE) of 99% in acidic electrolytes and maintain selectivity above 80% at a current density of 1 A cm, significantly surpassing the performance of CuS and SnS alone. Moreover, the excellent selectivity across pH-universal electrolytes demonstrates that dual-site activation is a promising strategy for designing highly efficient CO reduction reaction catalysts.