A Gold-Palladium Nanoparticle Alloy Catalyst for CO Production from CO 2 Electroreduction

Electrochemical CO 2 reduction reaction (CO 2 RR) is a promising technology for combining CO 2 reutilization and renewable electricity storage. For economic feasibility, better catalysts are required to overcome current limitations such as high overpotentials, poor faradaic efficiencies (FEs), and low current densities. Herein, size- and composition-controlled gold (Au)-palladium (Pd) bimetallic alloy nanoparticles prepared by a metal vapor synthesis technique together with the monometallic Au and Pd equivalent materials are investigated. X-ray diffraction and high-angle annular dark-field scanning transmission electron microscopy energy-dispersive X-ray spectroscopy analyses confirm the Au-Pd alloy formation with an average atomic ratio of 76 Pd wt% and 24 Au wt%. These bimetallic and the monometallic catalysts are characterized and tested for the electroreduction of CO 2 in electrochemical cells and also in a complete CO 2 electrolysis cell. Analysis of the reduction products shows a 100% CO 2 RR selectivity for CO. The FE for CO with respect to H 2 as high as 90% is obtained with Au-Pd/C by tuning the electrode structure. The Au/C and Pd/C catalysts also show a better selectivity for CO with no evidence of other CO 2 RR products. The Au-Pd alloy formation improves the FE of Pd for CO by suppressing the parasitic H 2 evolution reaction.