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.