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 coreshell architecture and demonstrate its performance in the light-driven degradation of organic contaminants. The hierarchical coreshell 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 coreshell 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 coreshell ACOF-1@BiOBr presents a paradigm shift in the development of covalent organic frameworks, especially in the field of photocatalysis.

Automated summary

A hierarchical coreshell structure of nanostructured ACOF-1@BiOBr was prepared and its performance in the degradation of organic contaminants under light irradiation was demonstrated. The enhanced photocatalytic activity of the ACOF-1@BiOBr system can be attributed to the synergy between ACOF-1 and BiOBr, which form a Type-II heterostructure that reduces the recombination rate of photogenerated charge carriers. The ACOF-1@BiOBr system also exhibited enhanced generation of superoxide radicals.