Water-Promoted C–C Coupling Reaction in Plasma-Catalytic CO2 Hydrogenation for Ethanol Production

The conversion of CO 2 into alcohols has attracted widespread interest. Herein, we present an approach for the plasma-catalytic CO 2 hydrogenation to ethanol over a Cu 2 O/CeO 2 catalyst under atmospheric pressure at a low temperature of ∼75 °C. The Cu 2 O/CeO 2 catalyst initially exhibits low ethanol selectivity (2.1%), which dramatically increases to 56% (78% total alcohols selectivity) with the assistance of water. D 2 O and H 2 18 O isotope-tracing experiments reveal the partial decomposition of water and the active involvement of its derivatives in the multistep pathway for ethanol synthesis. The multiple roles of H 2 O in switching alcohols production from methanol to ethanol are investigated. The plasma-generated OH in both adsorbed and radical states promotes C–C coupling via CO-H 2 CO bonding and facilitates hydrogenation through proton transfer. Additionally, the presence of adsorbed H 2 O and OH enhances the desorption of ethanol, further enhancing alcohol selectivity. It is envisaged that these findings would inspire value-added transformation of CO 2 to produce higher alcohols and pave the way for efficient chemical processes.