Hierarchical Core–Shell ACOF-1@BiOBr as an Efficient Photocatalyst for the Degradation of Emerging Organic Contaminants

We report the preparation of nanostructured ACOF-1@BiOBr with a hierarchical core–shell architecture and demonstrate its performance in the light-driven degradation of organic contaminants. The hierarchical core–shell photocatalyst was prepared using a facile solvothermal method that involves the formation of a BiOBr shell that encapsulates an azine-based covalent organic framework (ACOF-1) sphere. The ACOF-1@BiOBr hierarchical core–shell system manifested enhanced performance over the bare ACOF-1 or BiOBr in the photocatalytic degradation of different organic dyes employed in this study. Such an enhancement can be ascribed to the synergy between ACOF-1 and BiOBr, where the band gap alignment between ACOF-1 and BiOBr forms a Type-II heterostructure. In such a heterostructure, the movement of the photogenerated charge carriers can lower the recombination rate of the produced e–/h+ pairs and, hence, enhance the photocatalytic performance. The rate constants for photocatalytic degradation of the tested dyes were correlated to the surface interaction between the photocatalyst and the dyes. The data revealed that the generation of superoxide radicals was enhanced by the ACOF-1@BiOBr system, which demonstrates the significance of the multicomponent tandem photocatalyst. The hierarchical core–shell ACOF-1@BiOBr presents a paradigm shift in the development of covalent organic frameworks, especially in the field of photocatalysis.