Selectivity regulation of CO2 electroreduction through contact interface engineering on superwetting Cu nanoarray electrodes

Electrocatalytic CO2 reduction is a promising way to mitigate the urgent energy and environmental issues, but how to increase the selectivity for desired product among multiple competing reaction pathways remains a bottleneck. Here, we demonstrate that engineering the gas–liquid–solid contact interface on the electrode surface could tailor the selectivity of CO2 reduction and meanwhile suppress H2 production through regulated reaction kinetics. Specifically, polytetrafluoroethylene (PTFE) was utilized to modify a Cu nanoarray electrode as an example, which is able to change the electrode surface from aerophobic to aerophilic state. The enriched nano-tunnels of the Cu nanoarray electrode can facilitate CO2 transportation and pin gaseous products on the electrode surface. The latter is believed to be the reason that boosts the Faradaic efficiency of liquid products by 67% and limits the H2 production to less than half of before. This interface engineering strategy also lowered H2O (proton) affinity, therefore promoting CO and HCOOH production. Engineering the electrode contact interface controls the reaction kinetics and the selectivity of products, which should be inspiring for other electrochemical reactions.