Electrochemical Reduction of Carbon Dioxide to Hydrocarbons Using Copper Nanocomposite Catalyst
Authors: Muthuvel Madhivanan , Lu Fei , Botte Gerardine G 
Published: February 2020

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 (CO2) capture and sequestration approaches, conversion of CO2 to chemical compounds has been explored as another pathway to mitigate CO2 emissions problem. Synthesis of high value hydrocarbons, such as methane (CH4) and ethylene (C2H4), and alcohols such as methanol (CH3OH) and ethanol (C2H5OH) from emitted CO2 is a worthy sustainable process.

In the past few years, the electrochemical reduction of CO2 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 CO2 in aqueous solution.1-3 Varying Cu layer thickness improved selectivity between methane and ethylene; specifically more C2H4 was formed than CH4 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 CO2 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 CO2 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 CO2 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 CO2 reduction reaction. For all the electrolysis experiments, 0.1 M KHCO3 solution will be used with and without CO2 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 CO2 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 CO2 reduction reaction will depend on the preparation of Cu – reduced graphene oxide nanocomposite catalyst.

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