The electrochemical reduction of CO2 is strongly influenced by both the applied potential and the surface adsorption status of the catalyst. In this work a gas diffusion electrode (GDE) coated with Pd nanoparticles/carbon black (Pd/XC72) was used to study the electrochemical reduction of CO2. Cyclic voltammetric (CV) analysis of Pd/XC72 between 1.5V and −0.6V (vs. RHE) shows the formation of intermediates and the blocking of hydrogen absorption on the Pd nanoparticles (NPs) under a CO2 atmosphere. The relationships between the Faradaic efficiency/current density and the applied potential reveal that the onset potential of CO formation is around −0.4V. Moreover, the presence of adsorbed CO was confirmed through CV analysis of Pd/XC72 under CO2 and CO/He atmospheres. This demonstrates that H atoms and CO intermediates co-adsorb on the surface of the Pd NPs at an applied potential of around −0.4V. When the applied potential is more negative than −0.6V, adsorption of CO intermediates on the surface of the Pd NPs becomes dominant. Keywords: Palladium nanoparticles, Applied potential, Carbon monoxide, Electrochemical reduction of carbon dioxide
