Electrochemical behavior of CO2 reduction on palladium nanoparticles: Dependence of adsorbed CO on electrode potential

Abstract

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 1.5 V and − 0.6 V (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 − 0.4 V. 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 − 0.4 V. When the applied potential is more negative than − 0.6 V, adsorption of CO intermediates on the surface of the Pd NPs becomes dominant.