Multifunctional magnetic bentonite induced hierarchical BiOBr coupling Bi nanoparticles and oxygen vacancies for enhanced photocatalytic performance

The multiple roles of supporting carrier are always neglected especially in constructing superior photocatalyst. In this study, a multi-functional integrated magnetic bentonite/BiOBr-Bi (MB/BiOBr-Bi) was designed for effective antibiotic removal via a facile method using supporting carrier and loading Bi nanoparticles (Bi NPs). Magnetic bentonite (MB) as the photocatalyst carrier had the function of template-like agent, which could transform the original BiOBr morphology from piled sheets to hierarchical structures. Meantime, surface negative charge and abundant -OH groups of MB played vital roles in {001} facet expose and oxygen vacancies (OVs) generation of BiOBr. Based on this hierarchical structure, OVs at an appropriate concentration was in-situ uniformly formed on BiOBr through Bi reduction. The obtained MB/BiOBr-Bi exhibited good photocatalytic performance, excellent cycling stability and a significant decrease in antibiotic intermediate product toxicity, effectively degrading 92.4 % of tetracycline (TC) in 80 min. The main photocatalytic degradation mechanisms of TC removal by MB/BiOBr-Bi were interpretated from four aspects: the defect level owing to OVs, the surface plasma resonance (SPR) effect of Bi NPs, the molding function of MB, and the exposure of {001} active facets. This work highlights the neglected role of chosen carrier and delves into effects of carrier, Bi NPs and OVs, which provides a new idea for effective catalyst design.