(195b) Electrocatalytic Conversion of Plasma-Activated CO2+CO to C3+ Products and Alcohols

CO₂ upgrading to chemicals and fuels has been gaining significant attention. In electrocatalytic conversion, CO₂/CO can be converted to multi-carbon products such as ethylene, ethanol, and propanol, where C₃₊ products are particularly desirable. Efforts to improve the formation of multi-carbon products have focused on modifying catalytic active sites using microstructure engineering and alloying. Despite recent progress, achieving application-relevant performance requires further enhancement in the reaction rate and selectivity.

Non-thermal plasma provides another method of CO₂ conversion. Electron-mediated excitation in the ionized gas elevates the energy of molecules. Plasma conversion demonstrated relatively faster rates and unconventional reaction pathways. However, formation of multi-carbon products from plasma-activated CO₂ requires supply of hydrogen or short-chain hydrocarbons. Additionally, plasma conversion typically has large product distribution and low selectivity to target products.

Here, we implemented a coupled plasma-electrocatalytic conversion in which CO₂/CO was pre-activated by dielectric barrier discharge plasma and then electrocatalytically converted to multi-carbon products. Plasma activation of CO₂/CO improved conversion rates of multi-carbon products and alcohols such as ethanol and propanol. New reaction pathways were opened to methanol, acetylene, ethane, propane, and butane, which were only detected when plasma-activated CO₂/CO was electrocatalytically converted. Control experiments using ground-state gases simulating the plasma effluent revealed that the enhancements and the new products were the result of reactive plasma species participating in electrocatalytic reactions. To optimize the plasma-electrocatalytic process, it was critical to suppress generation of the CO₂/CO splitting products in plasma. We achieved O₂-free plasma activation by cofeeding CO₂ and CO, enhancing C₃₊ productivity and promoting the new reaction pathways. Further, we investigated the use of Cu-based alloys to enhance generation of alcohols as well as C₄₊ products. This work demonstrates advanced CO₂ upgrading to chemicals and fuels as well as synergistic combination of non-thermal plasma with electrocatalysis for converting molecules possessing strong chemical bonds.