In Situ Electrodeposition of Ag Nanoparticles for Electrocatalytic CO₂ Reduction to CO in Acidic Electrolyte at Industrial-Level Current Density

The electrochemical reduction reaction of CO 2 (CO 2 RR) driven by renewable electricity presents a sustainable pathway for converting CO 2 into valuable chemicals and fuels. However, achieving practical implementation requires the development of highly efficient and stable electrocatalysts. Conventional surface-loading methods typically involve catalyst synthesis followed by binder-assisted immobilization on electrodes, which often compromise catalytic activity and stability. This study demonstrates the controlled in situ electrodeposition of Ag-based catalysts with diverse morphologies directly onto gas diffusion electrodes (GDEs) in a flow cell system. Among the prepared catalysts, Ag-FC-40 mM@–0.12 V exhibits outstanding performance under acidic CO 2 RR conditions, achieving a CO Faradaic efficiency of 97.79% and a current density of 150 mA cm –2 . When the current density is increased to 300 mA cm –2, the CO Faradaic efficiency remains at 94.41%. This represents an improvement of more than 20% compared to the CO selectivity (70.50%) of conventional surface-loaded Ag catalysts and maintains over 90% selectivity during a 10 h stability test. In contrast, traditionally loaded Ag nanoparticles experience rapid deactivation. At an industrially relevant current density of 500 mA cm –2, Ag-FC-40 mM@–0.12 V retains a CO selectivity of 78.36%. Additionally, under a CO 2 flow rate of 4 mL min –1, it achieves a single-pass carbon efficiency (SPCE) of 49.75%. Scale-up experiments confirm minimal performance variation when the electrode area is increased from 1 cm 2 to 25 cm 2, demonstrating the feasibility of large-scale implementation. These findings highlight the potential of in situ electrodeposited Ag-based catalysts for efficient and stable CO 2 electroreduction, offering a promising route for scalable and sustainable carbon utilization.