Ultrathin oxygen-vacancy abundant WO3 decorated monolayer Bi2WO6 nanosheet: A 2D/2D heterojunction for the degradation of Ciprofloxacin under visible and NIR light irradiation

At present, environmental pollution caused by refractory organic pollutants becomes more serious. Semiconductor-based photocatalysis technology, an idea and continuable technology by solar-light-driven, is widely employed to address this situation. Here, oxygen-vacancy rich WO3 decorated monolayer Bi2WO6 nanosheet composite as an atomic scale heterojunction with high active species and ultrafast charge carrier transfer was rationally constructed. The atomic scale V-o-WO3/Bi2WO6 composite displayed remarkable photoactivity comparing with pristine V-o-WO3 and Bi2WO6 ultrathin nanosheet, and about 79.5% of Ciprofloxacin can be degraded within 120 min under visible light irradiation when 40 mg of photocatalyst was added into CIP solution (10 mg/L). The promoted photoactivity can be ascribed to the following points: (1) the composite possesses enormous surface pit, thereby expanding the species surface area and exposing more active site to promote antibiotic absorption; (2) the presence of abundant oxygen vacancy can facilitate the formation of more electrons, which can be consumed by adsorbed molecular oxygen to produce superoxide radical, thereby accelerating degradation organic pollutant; (3) ultrathin V-o-WO3 nanosheet decorated monolayer Bi2WO6 can shorten the charge carrier transfer distance and enlarge interface contact area, then ensuring remarkable photodegradation efficiency. The reasons for promoted photodegradation efficiency were elaborated based on experiments results and ESR analysis and the degradation pathways of CIP were recorded via [(LC-MS)/MS]. After 5 run for the degradation of CIP, V-o-WO3/Bi2WO6 composite also exhibited great photodegradation efficiency, thereby demonstrating its excellent stability and reusability. (C) 2019 Elsevier Inc. All rights reserved.