Fabrication of n-n isotype BiOBr-Bi2WO6 heterojunctions by inserting Bi2WO6 nanosheets onto BiOBr microsphere for the superior photocatalytic degradation of Ciprofloxacin and tetracycline

Abstract

Fabrication of n-n Isotype BiOBr-Bi 2 WO 6 Heterojunctions by Inserting Bi 2 WO 6 Nanosheets onto BiOBr Microsphere for the Superior Photocatalytic Degradation of Ciprofloxacin and Tetracycline. • Microwave-assisted hydrothermal synthesis of efficient n-n isotype BiOBr-Bi 2 WO 6 . • Novel 2D-3D nanosheet-insertion-microsphere construction boosted catalytic activity. • Strong interfaces between BiOBr and Bi 2 WO 6 enhanced e - /h + separation and transfer. • The BiOBr-Bi 2 WO 6 = 8:1 showed superior degradation of ciprofloxacin and tetracycline. • A detailed Z-scheme mechanism was elucidated based on experimental results. Ciprofloxacin (CIP) and tetracycline (TC) are emerging contaminants which seriously threaten the survival of aquatic life and human health. In this study, we report a facile and energy-efficient one-step hydrothermal strategy for the fabrication of n-n isotype BiOBr-Bi 2 WO 6 heterojunctions with nanosheet-insertion-microsphere morphology. Morphological characterizations indicated that two-dimensional (2D) n-Bi 2 WO 6 nanosheets were inserted or covered upon n-type three-dimensional (3D) BiOBr microspheres which acted as the support successfully restricted the aggregation of Bi 2 WO 6 nanosheets and supplied more active sites. The 2D Bi 2 WO 6 nanosheets enhanced the interfacial contact and improved visible-light absorption efficiency. Photocatalytic degradation experiments revealed that BiOBr-Bi 2 WO 6 = 8:1 exhibited superior CIP and TC degradation (90%and 96%, respectively) within 120 min as compared to that of the pristine BiOBr and Bi 2 WO 6 . Moreover, BiOBr-Bi 2 WO 6 = 8:1 also realized efficient photocatalytic degradation of Rhodamine B (100%) and Methylene blue (94%). Excellent stability and recyclability remained in BiOBr-Bi 2 WO 6 = 8:1 composite after five consecutive cycles. Based on the band structure analyses, and radical trapping and electron spin resonance characterization results, a possible Z-scheme path of charger transfer was proposed to elucidate the enhanced photocatalytic mechanism. This study offers a novel avenue to design efficient n-n isotype heterojunction with superior visible-light response for refractory antibiotics degradation.