Tailoring Copper Foam with Silver Dendrite Catalysts for Highly Selective Carbon Dioxide Conversion into Carbon Monoxide.

The present study outlines the important steps to bring electrochemical conversion of carbon dioxide (CO2) closer to commercial viability by using a large-scale metallic foam electrode as highly conductive catalyst scaffold. Due to its versatility, it was possible to specifically tailor three-dimensional copper foam through coating with silver dendrite catalysts by electrodeposition. The requirements of high yield CO2 conversion to carbon monoxide (CO) were met by tuning the deposition parameters towards a homogeneous coverage of the copper foam with nanosized dendrites, which additionally featured crystallographic surface orientations favoring CO production. The presented results evidence that Ag dendrites, owing a high density of planes with stepped (220) surface sites, paired with the superior active surface area of the copper foam can significantly foster the CO productivity. In a continuous flow-cell reactor set-up, CO faradaic efficiencies reaching from 85 % to 96 % for a wide range of low applied cathode potentials (< 1.0 VRHE) along with high CO current densities up to 27 mA/cm2 were achieved, far outperforming other tested scaffold materials. Overall, this research provides new strategic guidelines for the fabrication of efficient and versatile cathodes for CO2 conversion compatible with large-scale integrated prototype devices.