(650h) Bimetallic Effects on Zn-Cu Electrocatalysts Enhance Activity and Selectivity for the Conversion of CO2 to CO

Electrochemical CO₂ reduction (CO₂R) provides an avenue toward the sustainable production of fuels and chemicals. In this work, we report a cost-effective Zinc-Copper (Zn-Cu) bimetallic electrocatalyst for CO₂ reduction to generate CO under neutral conditions. The Zn-Cu bimetallic material is prepared by a facile galvanic-procedure in aqueous. With moderate overpotentials applied, Zn-Cu bimetallic catalyst exhibit dramatically improved intrinsic activity for CO formation compared to that of pure Zn and Cu, and comparable to Ag which is a commonly used state-of-the-art catalyst in CO₂ electrolyzers for CO production. Physical characterizations suggest that it is a Zn-rich surface for the Zn-Cu bimetallic catalysts during catalysis. Combinatorial catalysts with various of Zn to Cu ratios prepared by physical vapor deposition have been tested under the same CO₂R testing condition. Worth noting, we observed same trends across the Zn-Cu alloy system, corroborating the much higher CO selectivity for Zn rich Zn-Cu alloys compare to other alloys and intermetallics. Based on the comprehensive physical and electrochemical characterizations, and rationales from first principles theory, we suggest that the origin of this enhancement in intrinsic catalytic activity of Zn-Cu is resulted from an electronic effect from the bimetallic Zn-Cu sites, which can stabilize the key carboxyl intermediate during CO formation by reducing CO₂. Moreover, Zn-Cu bimetallic particles are also integrated into flow reactor with gas diffusion electrodes, and demonstrate improved electrocatalytic performance compared to Zn and Cu at industrially relevant currents. Overall, we believe the new insights obtained in this work provide catalyst design principles that can guide the future development of efficient and earth abundant CO-producing electrocatalysts.