Unlocking Photocatalytic CO₂ Conversion to Ethylene Glycol by Microdroplet-Enabled Interfacial Electric Field

The electrochemical carbon dioxide (CO₂) reduction features attractive potentials of carbon neutrality and chemical upgrading, while the types of products from photocatalysis or electrocatalysis still remain limited. The conversion of CO₂ into ethylene glycol, an important chemical that is typically produced by thermo-catalytic process, has not been achieved by photocatalysis or electrocatalysis. Herein, we demonstrate a microdroplet-enhanced photocatalytic strategy with a Pd-TiO₂ catalyst, which allows for efficient conversion of CO₂ into ethylene glycol with high selectivity. The electro-sprayed microdroplets provide a high interfacial electric field that facilitates deep reduction of CO₂ into *CH₃, as well as generation of reactive *OH intermediates to form CH₃OH. The in situ formed CH₃OH is further photo-catalytically activated to cleave a C-H bond to *CH₂OH, followed by the C-C coupling to produce ethylene glycol. Under 1-sun illumination, the electro-sprayed microdroplets and Pd-TiO₂ catalyst exhibited a high CO₂-to-ethylene glycol conversion rate of 2985 µmol L^-1 h^-1, which significantly outperformed those by only photocatalysis or only electro-sprayed microdroplets, revealing the capability of combining multiple energy fields for tuning reaction pathways and advancing green synthesis.