CO2 reduction on a nanostructured La0.5Ba0.5CoO3 perovskite: Electrochemical characterization and DFT calculations

Abstract

A La0.5Ba0.5CoO3 perovskite was evaluated as a catalyst for the electrochemical reduction of CO2. Nanocrystalline structures of La0.5Ba0.5CoO3 were synthesized using polycarbonate porous templates by microwave irradiation. Electrochemical characterization was carried out by linear sweep voltammetry, cyclic voltammetry and chronoamperometry. The electroreduction of CO2 produced HCOOH with a faradaic efficiency of 30% at − 0.9 V vs SHE as determined by ionic chromatography. The rotating ring-disc electrode configuration was used to further study the electroreduction processes. A faradaic efficiency of 85% at − 1.2 V vs SHE attributed to CO, was obtained from the disk and ring currents. In parallel, the adsorption process of CO2 and plausible reduction pathways to HCOOH and CO were studied by DFT calculation on the (001) and (110) orientations of the perovskite. The CO2 molecule strongly adsorbs at the oxygen surface sites through the C atom in a bent configuration, determining the *COOH species as the only possible intermediate. The formation and release of HCOOH becomes feasible under an applied potential of − 0.8 V and − 0.7 V vs SHE for the (001) and (110) orientations, respectively. On the other hand, the calculation showed that the release of CO is only feasible at the (001) surface plane for potentials below − 0.9 V vs SHE. The calculated applied potentials are in good agreement, both in trend and magnitude, with the experimental observations despite the model approximation of neglecting solvent effects.