Interfacial Imine-Bridging and Charge Directional Migration Dual Regulation of Zno/Covalent Organic Frameworks S-Scheme Heterostructure for Boosting Photocatalytic Co2 Reduction

Abstract

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, N-ZnO/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 N-ZnO to TAPT-DMTP COF upon hybridization and this S-scheme heterostructure dramatically lower 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 the vital roles in enhancing CO2 reduction.

Keywords: Covalent organic frameworks, Amino-modified ZnO, Imine-bridging, S-scheme heterojunction, photocatalytic CO2 reduction