Interfacial imine-bridging and charge directional migration dual regulation of ZnO/covalent organic frameworks S-scheme heterostructure for boosting photocatalytic CO2 reduction

Covalent organic frameworks (COFs) equipped with controllable porosity and excellent structural stability are regarded as promising candidates for photocatalytic CO₂ reduction, yet some inherent drawbacks including low CO₂ activation and sluggish charge carriers' transfer properties urgently need to be addressed. Herein, we developed an imine-bridged strategy to construct ZnO/COF heterostructure by integrating donor-acceptor COF (TAPT-DMTP COF) on the surface of amino-modified ZnO for photocatalytic CO₂ reduction. The optimal photocatalyst, NZnO/TAPT-DMTP COF-3, exhibited superior photocatalytic activity for reducing CO₂ to CO and CH₄, which was significantly higher than pristine COF and non-covalently bridged ZnO/TAPT-DMTP COF. Experimental and photo-electrochemical results reveal that the microstructure of TAPT-DMTP COF, interfacial imine-bridging and S-scheme heterojunction play a crucial role in promoting photoinduced charge transfer and separation, thus improving photocatalytic efficiency. Moreover, in-situ characterization and theoretical calculations indicate the photoinduced electrons transfer from NZnO to TAPT-DMTP COF upon hybridization, and this S-scheme heterostructure dramatically lowers the energy barrier of rate-determining step from *COOH to *CO. This work provides insight into the covalent-linked COF-based S-scheme photocatalyst and highlights its vital role in enhancing CO₂ reduction.