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

- Ag3PO4/TiO2@MoS2 with heterostructure and low bandgap was successfully synthesized.
- Ag3PO4/TiO2@MoS2 showed high photocatalytic activity and antiphotocorrosion ability.
- Ag3PO4/TiO2@MoS2 greatly enhanced the separation efficiency of electron-hole pairs.
- Possible photocatalytic degradation mechanism and pathway were illustrated.
- Ag3PO4/MoS2@TiO2 is a promising photocatalyst for degradation of organic pollutants.

We synthesized novel three-dimensional photocatalyst (Ag3PO4/TiO2@MoS2) with various content of TiO2@MoS2 by electrospining, sequential hydrothermal reaction and chemical deposition. The optimal content of TiO2@MoS2 in Ag3PO4/TiO2@MoS2 composites is 3.5 wt%, and the bandgap of Ag3PO4/TiO2@MoS2 (3.5 wt%) (1.85 eV) was much lower than that of pure Ag3PO4 (2.45 eV). Due to high conductivity of TiO2@MoS2 heterostructure, the separation efficiency of electron-hole pairs of Ag3PO4 was significantly improved so that Ag3PO4/TiO2@MoS2 (3.5 wt%) presented higher photocatalytic activity. More than 92% Methyl orange and Methylene blue were photodegraded over Ag3PO4/TiO2@MoS2 (3.5 wt%) in 12 min and 5 min, respectively. More importantly,TiO2@MoS2 could play the role of 'wire' to guide electrons captured by MoS2 and quickly transferred electrons into solution so that the recombination of electron-hole pairs and the reduction of silver irons were effectively restrained. Thus, Ag3PO4/TiO2@MoS2 (3.5 wt%) exhibited excellent anti-photocorrosion performance. Even after 10 cycling runs, Ag3PO4/TiO2@MoS2 (3.5 wt%) could degrade 75% and 92% of oxytetracycline and enrofloxacin, respectively, whereas Ag3PO4 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, Ag3PO4/TiO2@MoS2(3.5 wt%) is a promising photocatalyst for photodegradation of organic pollutants in the environmental protection.

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