One-step synthesis of a diverting erythrocyte-like heterojunction and the augmented activity of wastewater treatment: Morphology modulation, theoretical calculations and mechanism explanation

Abstract

As a green and sustainable technology, semiconductor photocatalysis mediated by heterojunction has shown great potential in the removal of organic pollutants from water environment. Yet, the nugatory recombination of photogenerated carriers induced by strong Coulombic forces lead to inferior photoactivity of semiconductor photocatalysts. In this paper, the erythrocyte-like composite (BiBrW) was designed to drive Z-type separation of photogenerated carriers through heterojunction interface by tight coupling between BiOBr and Bi2WO6. Combined with the results of characterizations, CTAB used in the synthesis process not only provides a bromine source but also serves as a surfactant to modulate the morphology of Bi2WO6 from petal-like to erythrocyte-like morphology. In contrast with the BiOBr/Bi2WO6 material fabricated via the in-situ growth method, the BiBrW composite displayed a uniform erythrocyte-like morphology with fewer grain boundaries by lamellar stacking of nanosheets. The combined effect of the construction of heterojunction and lessened grain boundaries endowed the BiBrW composite with augmented physicochemical properties, thereby enhancing its photocatalytic removal performance for various contaminants. Based on theoretical calculations, HPLC-MS tests and toxicity analysis, the reaction sites, degradation pathway and toxic evolution of ciprofloxacin (CIP) during the process of photodegradation were thoroughly elucidated, respectively. Moreover, the BiBrW catalyst still exhibits significant degradation performance for CIP under the excitation of natural sunlight. For different water qualities and distinct target pollutants (2-sec-butyl-4,6-dinitrophenol (DNBP), tetracycline (TC) and bisphenol A (BPA)), the catalyst maintains excellent photocatalytic removal capabilities, reflecting the superior universality of BiBrW catalyst. This research proposed novel mentality for preparation of heterojunction photocatalysts with less grain boundaries to assist in restoration of water environment.