Photoelectron Transfer Mediated by the Interfacial Electron Effects for Boosting Visible-Light-Driven CO2 Reduction

Abstract

Imine-linked covalent organic frameworks (COFs) are popular candidates for photocatalytic CO2 reduction, but high polarization of the imine bond is less efficient for π-electron delocalization between the linked building units, leading to low intramolecular electron transfer and poor photocatalytic efficiency. Herein, we present a structural and electronic engineering strategy through integrating the imine-linked COF consisting of Zn–porphyrin and Co–bipyridyl units with cadmium sulfide (CdS) nanowires to form a CdS@COF core–shell structure. The experimental and theoretical results have validated that CdS serves as the electron transfer channel through the interfacial electron effects, which induces photoelectron transfer from Zn–porphyrin to CdS and subsequent injection into Co–bipyridyl units for CO2 reduction. The as-prepared CdS@COF generates 4057 μmol g–1 CO in 8 h under visible-light irradiation, which is considerably higher than those of its neat CdS and imine-linked COF counterparts. This work provides protocols to tackle intramolecular charge transfer across polar linkages between photosensitizers and active sites for solar-to-chemical energy conversion.