Electrochemical Reduction of Carbon Dioxide to Hydrocarbons Using Copper Nanocomposite Catalyst

Increase in carbon dioxide, a greenhouse gas, emissions has resulted in widespread impact on climate and adversely affected the environment. In addition to carbon dioxide (CO 2 ) capture and sequestration approaches, conversion of CO 2 to chemical compounds has been explored as another pathway to mitigate CO 2 emissions problem. Synthesis of high value hydrocarbons, such as methane (CH 4 ) and ethylene (C 2 H 4 ), and alcohols such as methanol (CH 3 OH) and ethanol (C 2 H 5 OH) from emitted CO 2 is a worthy sustainable process. In the past few years, the electrochemical reduction of CO 2 to hydrocarbons and alcohols has gained importance. Among the metal catalysts, copper (Cu) has demonstrated higher current efficiencies and selectivity towards synthesis of hydrocarbon by electrochemical reduction of CO 2 in aqueous solution. 1-3 Varying Cu layer thickness improved selectivity between methane and ethylene; specifically more C 2 H 4 was formed than CH 4 on monolayer Cu catalyst. 4 Studies have reported use of Cu nanoparticles and high surface area catalyst supports, such as carbon nanotube, for enhanced faradic efficiency to reduce CO 2 to hydrocarbons. 5-6 This encouraged us to pursue graphene, a high surface area material, as support for the Cu catalyst to form a nanocomposite. The development of Cu – graphene nanocomposite as electrocatalyst for CO 2 reduction reaction is one of the objectives of this investigation. Electrochemical reduction of graphene oxide (commercial solution) will be combined with Cu electrodeposition to prepare the Cu – reduced graphene oxide nanocomposite. Another objective of this investigation is determining the operating conditions for electrochemical reduction of CO 2 to produce hydrocarbons at high efficiency and selectivity. The electrolysis experiments will be performed in an airtight cell with platinum (Pt) foil as anode electrode. A reference electrode (Ag/AgCl) will be used in the cell to apply different potential on Cu-based catalyst electrode (cathode) for CO 2 reduction reaction. For all the electrolysis experiments, 0.1 M KHCO 3 solution will be used with and without CO 2 saturation. The effect of catalyst morphology, applied electrode potential, electrolysis time, and electrolysis cell configuration will be evaluated with the gaseous products formed during the CO 2 reduction reaction. The gaseous products collected from the electrochemical cell will be analyzed using gas chromatograph instrument equipped with natural gas analyzer. Efficient and selective synthesis of hydrocarbon products by CO 2 reduction reaction will depend on the preparation of Cu – reduced graphene oxide nanocomposite catalyst. References Y. Hori, K. Kikuchi and S. Suzuki, Chemistry Letters , 14 , 1695 (1985). Y. Hori, K. Kikuchi, A. Murata and S. Suzuki, Chemistry Letters , 15 , 897 (1986). R. J. Lim, M. Xie, M. A. Sk, J-M. Lee, A. Fisher, X. Wang and K. H. Lim, Catalysis Today , 233 , 169 (2013). R. Reske, M. Duca, M. Oezaslan, K. J. P. Schouten, M. T. M. Koper and P. Strasser, The Journal of Physical Chemistry Letters , 4 , 2410 (2013). K. Manthiram, B. J. Beberwyck and A. P. Alivisatos, Journal of the American Chemical Society , 136 , 13319 (2014) C. Genovese, C. Ampelli, S. Perathoner and G. Centi, Journal of Catalysis , 308 , 237 (2013).