Constructing the covalent organic framework and In2O3 composites via covalent bonds towards excellent visible-light photocatalytic hydrogen evolution

Covalent organic frameworks (COFs) are particularly superior platforms for photocatalysis due to their unique pore-like structures and strong covalent forces between the frameworks. However, challenges still exist in improving photocatalytic performance. Rationally combining the advantages of inorganic and organic semiconductors to produce heterojunctions has obvious applications for improving the photocatalytic activity of materials. In this work, three COFs (BDA-HTA-COF, BDA-DHTA-COF and BDA-THTA-COF) and In2O3 are covalently bonded together for the first time to construct a heterojunction. The obtained BDA-THTA-30 shows the highest photocatalytic hydrogen production activity of 9691.84 μmol g−1h−1, which is 10.1 and 128.3 times higher than those of BDA-THTA-COF and In2O3, respectively. Further studies confirm that covalent bonding between In2O3 and the components of BDA-THTA-COF could significantly improve the separation and transfer rate of light-generated charges in the composites, leading to efficient hydrogen evolution activity. This bond development and covalent hybridization approach facilitates the development of photocatalysts for COFs.