Strengthened photocatalytic removal of bisphenol a by robust 3D hierarchical n-p heterojunctions Bi₄O₅Br₂-MnO₂ via boosting oxidative radicals generation

Design and creation of photocatalytic systems with favorable microstructural and morphological merits are quite crucial to heighten removal of environmental hormones. For such purpose, in the current study n-type Bi4O5Br2 and p-type MnO2 were specially selected to construct three-dimensional (3D) hierarchical composites Bi4O5Br2MnO2 (MB) via a facile one-pot procedure. Through thorough and systematical analyses, the existence of both expected components was confirmed in composites and these heterojunction MB composites showed significantly improved photocatalytic degradation of bisphenol A (BPA) under visible light. Particularly, the best candidate 0.5 MB owned the largest Kapp value 11.03 x 10-3 min-1 that was about 3.89 and 1.81 times those of bare Bi4O5Br2 and mechanical mixture 0.5 MB, which primarily attributed to strengthened visible-light absorption, effective integration of favorable morphologies, proper chemical composition, and efficient spatial separation of induced charge carriers through n-p heterojunction domains and thus boosted generation of oxidative radicals in a Z-Scheme model. In addition, other parameters possibly influenced photocatalytic degradation performance such as catalyst dosages, initial concentrations of BPA, pH values, and involvement of inorganic anions were also explored. Moreover, some intermediates were detected by GC-MS analysis to provide a plausible degradation path of these robust 3D hierarchical heterojunctions with satisfactory reusability and structural stability.