Heterojunctions Based on BiOBr Nanosheets Decorated on α‑Bi2O3 for Photodegradation of Rhodamine B.

Photocatalysis is extensively implemented in organic pollutant degradation, and the critical point is to develop outstanding and stable photocatalysts. Herein, the synthesis of coral reef-like α-Bi₂O₃/BiOBr heterostructure photocatalysts involves the in situ growth of BiOBr nanosheets onto α-Bi₂O₃, with the latter derived through calcination utilizing a bismuth-based metal–organic framework (CAU-17) as the precursor. Under simulated sunlight, the 20% α-Bi₂O₃/BiOBr heterojunction degraded nearly 97.7% of RhB in 60 min, while pure α-Bi₂O₃ and BiOBr nanosheets degraded only 7.8 and 65.3%, respectively. Furthermore, the 20% α-Bi₂O₃/BiOBr nanocomposite exhibited superior recycling stability, degrading 86.6% RhB after four cyclic experiments. This is attributed to the fact that the nanoscale α-Bi₂O₃ material obtained by calcination can retain the exoteric diffusion channels of CAU-17, making α-Bi₂O₃/BiOBr heterojunctions have an enormous specific surface area, providing more adsorption sites and promoting their photocatalytic capacity. Free radical capture tests and electron paramagnetic resonance measurements indicated that h⁺ and ^•O₂^– were the primary active substances during photodegradation. On the basis of that, a feasible photodegradation mechanism of type II α-Bi₂O₃/BiOBr heterojunctions was proposed. This study opens up the possibility of designing type II heterojunctions with MOFs as precursors for dye degradation. [ABSTRACT FROM AUTHOR]