Rational design of defect metal oxide/covalent organic frameworks Z-scheme heterojunction for photoreduction CO2 to CO

Z-scheme heterostructure consisting of covalent organic frameworks (COF) and inorganic semiconductor possesses tremendous potential for achieving efficient photoreduction of CO2. However, the precise design and rationalization of the interaction between COF and inorganic semiconductors remains a great challenge. Herein, the interaction of different N-sites on T−COF framework with defect TiO2 and stoichiometric TiO2 is investigated by density functional theory. The theoretical analysis suggests that the amine group of T−COF could provide an energetically favored binding site towards defect TiO2. Accordingly, a stable Z-scheme heterostructure with well-defined chemical bonding between Ti3+ and −NH2, and well-engineered geometry configuration through in situ anchoring defect TiO2 on the surface of amine-functionalized T−COF sphere is designed. The obtained heterostructure exhibits a high CO2-to-CO conversion efficiency, with nearly 100 % CO selectivity and an apparent quantum efficiency of 6.81 % at 365 nm. This work could provide guidance for the rational design of Z-scheme heterostructure photocatalysts for photocatalytic applications in high efficiency.