Electrochemical CO2 Reduction to Formic Acid at Low Overpotential and with High Faradaic Efficiency on Carbon-Supported Bimetallic Pd–Pt Nanoparticles

The electrochemical reduction of CO2 has attracted significant interest recently, as it is a possible reaction for the storage of renewable energy. Here, we report on the synthesis of PdxPt(100–x)/C nanoparticles and their electrocatalytic properties for the reduction of CO2 to formic acid, compared with their activity for the reverse oxidation of formic acid to CO2. We find that PdxPt(100–x)/C nanoparticles have a very low onset potential for the reduction of CO2 to formic acid of ca. 0 V vs RHE, which approaches the theoretical equilibrium potential of 0.02 V vs RHE for this reaction. Furthermore, the Pd70Pt30/C catalyst shows a faradaic efficiency of 88% toward formic acid after 1 h of electrolysis at −0.4 V vs RHE with an average current density of ∼5 mA/cm2. Therefore, this catalyst shows a competing or even better faradaic efficiency toward formic acid compared to recently reported catalysts, at a substantially lower overpotential, while avoiding a strong deactivation that was observed with previously reported Pd-based catalysts.