Electric-field-driven CO2 mass transfer at microdroplet interfaces boosts efficient ethanol generation.

The electrocatalytic CO2 reduction reaction (CO2RR) efficiently converts CO2 into high value-added products, but its reaction kinetics are still limited by CO2 mass transfer from the gas atmosphere to the catalyst surface. In this work, a hydrophobic AlCu@b-COF served as a customized microdroplet system catalyst for the CO2RR, achieving a maximum ethanol yield of 23.76 µmol L-1 g-1, representing a 40.97-fold enhancement compared to the conventional bulk phase system. The operando Raman spectroscopy and Debye length calculation analysis revealed an enhanced electric field gradient and compressed electric double layer due to the aggregation of CO3 2- and related anions at the interface of the microdroplets. Further operando Raman measurements and classical molecular dynamics simulations provided complementary evidence for the interfacial environment associated with CO2˙- transport, supporting a contribution of the enhanced interfacial electric field to CO2˙- mass transfer. This study provides a theoretical basis and technical support for the design and mechanism exploration of microdroplet-induced high-performance reaction systems.