Fastening Br^– Ions at Copper–Molecule Interface Enables Highly Efficient Electroreduction of CO₂ to Ethanol

Developing advanced electrocatalysts to convert CO2 into liquid fuels such as ethanol is critical for utilizing intermittent renewable energy. The formation of ethanol, however, is generally less favored compared with the other hydrocarbon products from Cu-based electrocatalysts. Herein, we construct an efficient electrocatalyst for ethanol formation based on dodecanethiol-modified CuBr, which in situ generates a robust Br-doped Cu–thiol interface. The obtained electrocatalyst shows a significantly enhanced C2+ Faradaic efficiency of 72%, among which the Faradaic efficiency of ethanol is 35.9%. Notably, the ratio of ethanol to ethylene significantly increases from 0.32 for pristine CuBr to 1.08 for dodecanethiol-modified CuBr. The improved electrocatalytic activity is related to the modulated adsorption energy of key intermediates on the Br-doped Cu–thiol interface as verified by density functional theory (DFT) calculations. The present study highlights the great potential of utilizing hybrid metal–molecule interfaces for improving electrocatalytic CO2 conversion.