Design of a Bimetallic Electrode (Ag-Cu) for Electrochemical Reduction of Carbon Dioxide (CO2) to Value-Added Chemical Products.

Abstract

KEYWORDS: Bimetallic electrode (Ag-Cu), electrochemical reduction of carbon dioxide, electrocatalyst, electrodeposition, faradaic efficiency.Carbon dioxide (CO2) is the last of the by-products in all processes that involve the complete oxidation or combustion of any carbonaceous organic matter. Considering this and the high amount of fossil energy sources, CO2 is currently considered as environmentally harmful. Given this scenario, it is essential to re-value carbon dioxide, since it represents a potential raw material or carbon source for obtaining value-added chemical products. In this context, the electrochemical reduction of CO2 represents an attractive alternative since it has proven to pose various advantages over other current technologies to conduct the molecular conversion of this compound.The efficiency of the electrochemical reduction of CO2 depends to a large extent on the activity and selectivity of the cathode electrocatalyst, so that the appropriate electrocatalysts are necessary to promote the chemical reactions of electrosynthesis. Therefore, a key point for the electrochemical reduction of CO2 is the selection of such an electrocatalyst.In this work, a bimetallic silver-copper catalyst (Ag-Cu) with different Cu concentration was prepared and its faradaic efficiency was established in the electrochemical reduction of CO2 towards added value chemical compounds like methanol, acetic and formic acids. The modification was made on a Ag sheet (1 mm thick, 2 cm2 surface area and 99.9% purity), the deposition electrolyte was prepared from a 1.0 M solution of copper sulphate pentahydrate (CuSO4 • 5H2O 99.8 %). The surface modification of the bimetallic electrode was performed by electrolysis at controlled potential (-520 mV vs the Ag / AgCl electrode) at three different programmed times: 5, 10 and 15 min. The so prepared electrodes were characterized by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) and tested in the electrochemical reduction of CO2 in aqueous medium. The by-products were determined by HPLC-IR. The faradaic efficiencies was determined for the reaction products. REFERENCES - ElMekawy, A., Hebag, M. H., Mohanakrishna, G., Elbaz, A. F., y Bulut, M., 2016. Technological advances in CO2 conversion electro-biorefinery: A step toward commercialization. Bioresource Technology, pp. 752-766.- Ganesh, I., 2016. Electrochemical conversión of carbon dioxide into renewable fuel chemicals – The role of nanomaterials and the comercialization. Renewable and Sustainable Energy Reviews, 59, pp. 1269-1297.- Kumar, B., Brian, J. P., Atla, V., Kumari, S., Bertram, K. A., White, R. T., y Spurgeon, J. M., 2016. New trends in the devolopment of heterogeneous catalysts for electrochemical CO2 reduction, Catalysis Today, 270, pp.19-30.- Merino, G. I., 2016. Electrochemical membrane reactors for the utilisation of carbon dioxide. Chemical Engineering Journal, 296, pp. 204-221.