Regulating the Layer Stacking Configuration of CTF-TiO₂ Heterostructure for Improving the Photocatalytic CO₂ Reduction

Herein, covalent triazine frameworks in eclipsed AA and staggered AB stacking modes are respectively used for the in-situ growth of TiO₂, and two heterostructures are obtained. Due to the highly organized stacking of the molecular layer in CTF-AA that strengthens the interlayer interaction, the light absorption and carrier migration of CTF-AA/TiO₂ are both enhanced in comparison to those of its component or CTF-AB/TiO₂. Correspondently, the photocatalytic CO₂ reduction reaction (CO₂RR) of CTF-AA/TiO₂ proffers 9.19 μmol·g^-1·h^-1 CH₄ and 2.32 μmol·g^-1·h^-1 CO production, about 9.2 and 4.3 times greater than that of pristine TiO₂, respectively. Even though the innate photoresponse of the triazine unit endows CTF-AB/TiO₂ with augmented light capturing, its photocatalytic CO₂ conversion is relatively insignificant. According to the analyses of the planar-averaged electron density difference and Bader charge, the unproductive CO₂ efficiency might be due to the insufficient interfacial electron transfer from TiO₂ to CTF-AB. Given that the Δ<i>G</i> (-3.22 eV) of CHO intermediate generation is lower than that of CO desorption (-1.23 eV), the reaction tends to further generate CH₄ other than yielding CO. This study could shed fresh light over the reasonable design of effective photocatalytic heterostructures.