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

Abstract

Herein, covalent triazine frameworks in eclipsed AA and staggered AB stacking modes are respectively used for the in-situ growth of TiO 2 , 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/TiO 2 are both enhanced in comparison to those of its component or CTF-AB/TiO 2 . Correspondently, the photocatalytic CO 2 reduction reaction (CO 2 RR) of CTF-AA/TiO 2 proffers 9.19 μmol•g −1 •h −1 CH 4 and 2.32 μmol•g −1 •h −1 CO production, about 9.2 and 4.3 times greater than that of pristine TiO 2 , respectively. Even though the innate photoresponse of the triazine unit endows CTF-AB/TiO 2 with augmented light capturing, its photocatalytic CO 2 conversion is relatively insignificant. According to the analyses of the planar-averaged electron density difference and Bader charge, the unproductive CO 2 efficiency might be due to the insufficient interfacial electron transfer from TiO 2 to CTF-AB. Given that the ΔG (−3.22 eV) of CHO intermediate generation is lower than that of CO desorption (−1.23 eV), the reaction tends to further generate CH 4 other than yielding CO. This study could shed fresh light over the reasonable design of effective photocatalytic heterostructures.