Scheme-II heterojunction of Bi2WO6@Br-COFs hybrid materials for CO2 photocatalytic reduction

Combining inorganic semiconductors with covalent organic frameworks (COFs) to construct excellent hybrid materials is a promising strategy for solar-driven CO2 reduction, but how to modulate the charge migration to achieve optimal catalytic efficiency remains a great challenge. Herein, we successfully fabricated well-defined core–shell structured HBWO@Br-COFs hybrid materials using the nano-flowered Bi2WO6 (HBWO) as the core and the triazine-based imine-functionalized Br-COF as the shell. The electrostatic attraction between HBWO and Br-COF leads to the formation of C-O covalent bond and a tight and stable interface. Impressively, the Scheme-II heterojunction was favorably formed at the interfacial layer between the core and the shell, and they provided a stable platform for the rapid transfer of the photogenerated charge and efficient separation of the electron-hole pairs, resulting in excellent photocatalytic CO2 reduction. The resultant HBWO@Br-COF-2 exhibited high CO yield rate of 19.9 μmol·g−1·h−1, about 3.4 times higher than HBWO (5.8 μmol·g−1·h−1) and 2.6 times greater than Br-COF (7.53 μmol·g−1·h−1), respectively. This work provides helpful ideas for the optional design and facile fabrication of the novel inorganic–organic hybrid materials for photocatalytic CO2 reduction.