Proton-Transfer\nDynamics Regulates CO<sub>2</sub> Electroreduction\nProducts via Hydrogen Coverage

Electrochemical conversion of CO<sub>2</sub> to hydrocarbons\nis\na promising approach to carbon neutrality and energy storage. The\nformation of reaction intermediates involves crucial steps of proton\ntransfer, making it essential to understand the role of protons in\nthe electrochemical process to control the product selectivity and\nelucidate the underlying catalytic reaction mechanism of the CO<sub>2</sub> electrochemical reduction (CO<sub>2</sub>RR). In this work,\nwe proposed a strategy to regulate product selectivities by tuning\nlocal proton transport rates through a surface resin layer over cuprous\noxides. We systematically studied the influence of proton transfer\nrates on product selectivities by regulating the polymerization degree\nof resorcinol-formaldehyde resin (RF). The production of C<sub>2</sub> compounds and CH<sub>4</sub> could be switched through an RF coating\nwith the maximum CH<sub>4</sub> Faradaic efficiency of 51% achieved\nat current densities close to the amperage level. Both experimental\nand theoretical calculation results suggest that the resin layer can\nsubtly alter proton transfer rates during the electrochemical process,\nthereby influencing the hydrogen coverage on catalytic sites and ultimately\nguiding the overall electrochemical performance toward product selectivity.