Spatial Coupling of Photocatalytic CO₂ Reduction and Selective Oxidation on Covalent Triazine Framework/ZnIn₂S₄ Core–Shell Structures

Abstract

Photocatalytic CO2 reduction coupled with alcohol oxidation to aldehyde presents a promising strategy for the simultaneous production of fuels and valuable chemicals. The efficiency of the coupled photocatalytic reactions remains low due to poor charge separation, difficulty in CO2 activation, and uncontrolled compatibility between reactions. This work presents S‐bridged covalent triazine framework (SCTF) core‐ZnIn2S4 shell photocatalysts for simultaneous CO2 reduction and selective furfural synthesis at distinct active sites. As evidenced by in situ X‐ray photoelectron spectroscopy and Kelvin probe force microscopy, photogenerated electrons in the composite photocatalysts transfer from the ZnIn2S4 shell to the SCTF core, improving charge separation. Experimental and theoretical results confirm that the presence of pyridine N atoms (Lewis basic sites) in SCTF enhances CO2 adsorption, thereby reducing the energy barrier for *COOH generation and promoting *CO production. Meanwhile, furfuryl alcohol oxidation and deprotonation occur on ZnIn2S4 by consuming photogenerated holes, which in turn benefits the conversion of CO2 to CO. As a result, the optimized SCTF/ZnIn2S4‐0.2 core/shell photocatalyst exhibited a superior CO production yield of 263.5 µmol g−1 and 95% conversion of furfuryl alcohol to aldehyde under simulated sunlight irradiation.