Ultrathin oxygen-vacancy abundant WO decorated monolayer BiWO 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 WO decorated monolayer BiWO nanosheet composite as an atomic scale heterojunction with high active species and ultrafast charge carrier transfer was rationally constructed. The atomic scale V-WO/BiWO composite displayed remarkable photoactivity comparing with pristine V-WO and BiWO 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-WO nanosheet decorated monolayer BiWO 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-WO/BiWO composite also exhibited great photodegradation efficiency, thereby demonstrating its excellent stability and reusability.