Template-free formation of BiOCl double-shelled hollow microspheres with enhanced carbamazepine removal efficiency

Constructing three-dimensional (3D) hierarchical structure is regarded as an effective strategy to alleviate the inherent drawbacks of the BiOCl bulk structure and realize the optimization of photocatalytic performance. Herein, a unique BiOCl double-shelled hollow microsphere structure with adjustable shell thickness is fabricated through a template-free one-pot solvothermal method for the first time. A plausible formation mechanism is proposed by exploring the morphological changes during the growth process. The as-obtained hollow micro -spheres photocatalyst exhibits excellent carbamazepine (CBZ) degradation efficiency (97.5%) under simulated solar irradiation, the corresponding apparent rate constant is about 4 times and 3 times than that of conventional BiOCl solid microspheres. The experimental and characterization results show that the existence of nanosheet subunits and porous structures shorten the diffusion length of charge carriers, which is conducive to the sepa-ration and transfer of photogenerated. Meanwhile, the construction of double-shelled hollow structure achieves higher light utilization. This work demonstrates the superior performance of catalysts with hierarchical hollow structures for pollutant degradation and provides new ideas to further optimize the photocatalytic performance of BiOCl-based materials.