BiOBr/PBCD-B-D dual-function catalyst with oxygen vacancies for Acid Orange 7 removal: Evaluation of adsorption-photocatalysis performance and synergy mechanism

The fabrication of a dual-function material is an effective strategy to promote the degradation of pollutants through the synergy of adsorption and photocatalysis. Herein, we introduce an amphiphilic hyper-crosslinked porous cyclodextrin polymer (PBCD-B-D) into bismuth oxide bromide (BiOBr) via a one-pot solvothermal method to construct three-dimensional (3D) spherical flower-shaped BiOBr/PBCD-B-D (BOP) composites for removing the organic dye Acid Orange 7 (AO7). The prepared BiOBr composite loaded with 24% PBCD-B-D (BOP-24) displayed an optimal adsorption–photocatalytic effect. Under different concentration gradients, the pseudo first-order reaction rate constant of BOP-24 was 2–5 times that of BiOBr after visible-light irradiation. The unique cavity structure of PBCD-B-D resulted in a strong inclusion ability, which could concentrate organic pollutants and shorten the mass transfer distance. The introduction of PBCD-B-D to BiOBr led to an increase in the specific surface area and pore volume, which not only provided a large number of adsorption sites and active centers but also produced oxygen vacancies to improve charge separation. In addition, a possible degradation pathway was proposed for AO7 based on 3D excitation-emission matrix fluorescence spectra and analysis by liquid chromatography-mass spectrometry. This work combines the advantages of both adsorption and photocatalytic technologies for environmental remediation, and opens an avenue for dual-function high-surface-area adsorbent/photocatalysts via a one-pot in situ method.