Comparative Study of Carbon Supported Pb, Bi and Sn Catalysts for Electroreduction of Carbon Dioxide in Alkaline Medium

A gas diffusion electrode type arrangement was employed to evaluate carbon supported Pb, Bi and Sn nanopowders as electrocatalysts for electrochemical reduction of carbon dioxide in alkaline media (0.5 M NaHCO3). The structural analysis, shape and topographical characterization, and the surface composition analysis of the catalysts were performed by XRD, SEM, TEM and XPS, respectively. The electrochemical techniques used were cyclic voltammetry, linear sweep voltammetry and chronoamperometry. Cyclic voltammetry was used to study the basic redox properties of the surface, while linear sweep was used to measure the response in argon and carbon dioxide saturated solutions. Chronoamperometry was carried out at four potentials to compare the products and their rate of formation for all the catalysts at ambient temperature and pressure. The formate production rate was observed to be highest for lead among the three catalysts evaluated. The value obtained was 0.576 mmol/h at −1.94 V vs RHE with a Faradaic efficiency of ∼ 30%. Further, the activity was found to be stable during the electrolysis and the current density was almost ∼35 mA/cm2geo. Based on the experiments conducted in this study, a comparative result of activity towards CO2 electroreduction to formate was concluded as Pb > Bi > Sn.