Preparation of three-dimensional Ag3PO4/TiO2@MoS2 for enhanced visible-light photocatalytic activity and anti-photocorrosion

We synthesized novel three-dimensional photocatalyst (Ag 3 PO 4 /TiO 2 @MoS 2 ) with various content of TiO 2 @MoS 2 by electrospining, sequential hydrothermal reaction and chemical deposition. The optimal content of TiO 2 @MoS 2 in Ag 3 PO 4 /TiO 2 @MoS 2 composites is 3.5   wt%, and the bandgap of Ag 3 PO 4 /TiO 2 @MoS 2 (3.5   wt%) (1.85   eV) was much lower than that of pure Ag 3 PO 4 (2.45   eV). Due to high conductivity of TiO 2 @MoS 2 heterostructure, the separation efficiency of electron-hole pairs of Ag 3 PO 4 was significantly improved so that Ag 3 PO 4 /TiO 2 @MoS 2 (3.5   wt%) presented higher photocatalytic activity. More than 92% Methyl orange and Methylene blue were photodegraded over Ag 3 PO 4 /TiO 2 @MoS 2 (3.5   wt%) in 12   min and 5   min, respectively. More importantly,TiO 2 @MoS 2 could play the role of ‘wire’ to guide electrons captured by MoS 2 and quickly transferred electrons into solution so that the recombination of electron-hole pairs and the reduction of silver irons were effectively restrained. Thus, Ag 3 PO 4 /TiO 2 @MoS 2 (3.5   wt%) exhibited excellent anti-photocorrosion performance. Even after 10 cycling runs, Ag 3 PO 4 /TiO 2 @MoS 2 (3.5   wt%) could degrade 75% and 92% of oxytetracycline and enrofloxacin, respectively, whereas Ag 3 PO 4 degraded 23% and 44%. In addition, the possible photodegradation pathways of oxytetracycline and enrofloxacin were proposed, demonstrating that the photodegradation mechanisms involving oxidizing/shedding of functional groups firstly and opening the ring sequentially. Further detection of reactive oxidative species indicated that holes were the main active oxidizing species involved in the photocatalytic reaction process. Thus, Ag 3 PO 4 /TiO 2 @MoS 2 (3.5   wt%) is a promising photocatalyst for photodegradation of organic pollutants in the environmental protection.