Interfacial hydrophobicity engineering enhances mass transfer and reaction kinetics in CO2 electroreduction

Efficient CO 2 delivery remains a key bottleneck in electrocatalytic CO 2 reduction due to the low solubility and sluggish diffusion of CO 2 in aqueous electrolytes. Here we demonstrate that rational modulation of the interfacial microenvironment can effectively alleviate these mass-transport constraints and substantially enhance reaction efficiency. Hydrophobic channels constructed by embedding polytetrafluoroethylene nanoparticles enrich the local CO 2 concentration and facilitate rapid gas-liquid transport, as supported by finite-element simulations. This microenvironmental engineering enables CO Faradaic efficiency of 94.6% at −0.8 V versus the reversible hydrogen electrode. Further incorporation of a conductive and hydrophobic polythiophene layer balances gas accessibility with charge-transfer kinetics, delivering CO Faradaic efficiency exceeding 98.6% and sustaining above 90% during the continuous operation in a flow-cell configuration. This work highlights the pivotal role of interfacial microenvironment regulation in overcoming intrinsic transport limitations, offering a robust strategy for highly efficient and durable CO 2 -to-CO conversion.