One-step synthesis of oxygen vacancy-rich BiOBr/TiO2 composite: Ultrafast adsorption-photocatalytic performance and mechanism

Abstract

A novel 3D bird’s nest-like BiOBr/TiO2 (BT) composite with abundant reactive sites and large specific surface area was synthesized via a one-pot solvothermal method. The unique 3D structure endowed with BiOBr nanosheets on its surface can interconnect and coat with metastable TiO2 nanoparticles, which established a compact electron transport pathway. When exposed to visible light, BT showcased a remarkable RhB (50 mg/L) removal efficiency of 100.00 % within only 10 min. Meanwhile, BT showed an ultra-high reaction rate constant of 0.63 min−1, which was 16.15 and 87.50 times higher than those of single-component BiOBr and TiO2, respectively. BT also exhibited exceptional reusability and maintained over 99.38 % degradation efficiency for RhB after multiple cycles. Additionally, tetracycline (TC) was adopted as a common antibiotic to validate the versatility of the catalyst (60 mg/L, 94.06 %). The presence of oxygen vacancies and metallic Bi, ameliorated the charge separation and transfer by generating more adsorption sites and active centers, dramatically enhancing the adsorption and photocatalytic properties. Attractively, BT was innovatively explored for outdoor natural light degradation and rapid removal of RhB stained on cotton fabrics, showing the potential for practical applications. Moreover, the adsorption and photocatalytic mechanisms, possible degradation pathways of RhB and the underlying toxicity assessment of the intermediates were also elaborated. And the solution after photocatalytic treatment also exhibited considerable biocompatibility through the growth of wheat seeds and is expected to be used in agricultural field. Overall, this work opened a new avenue for the facile design of efficient adsorption-photocatalysis materials.