Carbon modified silver thin-film catalysts for electrochemical reduction of CO2 to syngas with tunable H2/CO ratio

This study investigates carbon (C)-modified silver (Ag) thin film catalysts for electrochemical syngas production. The Ag-C catalyst is synthesized using a co-deposition process with separate C and Ag sputtering targets. It is found that co-deposition with C increases nucleation rate during film growth, which reduces particle size and increases the surface area, as well as increasing the selectivity for the hydrogen evolution reaction (HER). A 10-fold improvement in the geometric current density is obtained for the Ag-C thin film relative to Ag due to a high abundance of active sites, and a H2/CO ratio between 1.4 and 2.5 is attained within the potential range of − 0.6 to − 1.0 V. vs RHE. Thus, regulating the C concentration allows the H2/CO ratio to be tuned while maintaining a surface architecture that permits large geometric current densities, both being desirable properties for catalysts used in syngas applications.