title: The synergetic effect of MoS₂ and graphene on Ag₃PO₄ for its ultra-enhanced photocatalytic activity in phenol degradation under visible light.
abstract: The photo-degradation of organic pollutants using solar light is an attractive chemical process for water pollution control. In this study, we synthesized a new composite material consisting of silver phosphate (Ag₃PO₄) sub-microcrystals grown on a layered molybdenum disulfide (MoS₂) and graphene (GR) hybrid as a high-performance photocatalyst for the degradation of toxic organic pollutants. This composite photocatalyst was prepared via a simple two-step hydrothermal process that used sodium molybdate, thiourea and graphene oxide as precursors for the MoS₂/GR hybrid and silver nitrate for the Ag₃PO₄ sub-microcrystals. The composite Ag₃PO₄-0.02(MoS₂/0.005GR) was found to be the most effective catalyst for the photo-decomposition of 2,4-dichlorophenol under simulated solar light and visible light (λ ≥ 420 nm). The photocatalyst was also highly active for the degradation of nitrophenol and chlorophenol. The ultra photocatalytic activity of the novel catalyst arose from the synergetic effects of MoS₂ and GR as cocatalysts in the composite. MoS₂/GR nanosheets served as electron collectors for the interfacial electron transfer from Ag₃PO₄ to electron acceptors in the aqueous solution and thus enhanced the separation of the photo-generated electron-hole pairs and made the holes more available for organic oxidation. In addition, the presence of MoS₂ and GR provided more active adsorption sites and allowed for the activation of dissolved O₂ for organic degradation in water.
authors.affiliation: Environmental Engineering Research Centre, Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China. xlia@hkucc.hku.hk.
authors.forename: Wen-Chao
authors.initials: WC
authors.lastname: Peng
authors.forename: Xi
authors.initials: X
authors.lastname: Wang
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Li
mesh_terms: D002384:Catalysis; D002733:Chlorophenols / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D008027:Light; D008982:Molybdenum / Q000737:chemistry*; D009596:Nitrophenols / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry*; D010782:Photolysis / Q000528:radiation effects; D018030:Silver Compounds / Q000737:chemistry*; D013890:Thiourea / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D002733:Chlorophenols; D004220:Disulfides; D009596:Nitrophenols; D010087:Oxides; D010710:Phosphates; D018030:Silver Compounds; D014874:Water Pollutants, Chemical; D006108:Graphite; D008982:Molybdenum; C024687:sodium molybdate(VI); D013890:Thiourea; C082964:molybdenum disulfide; C039072:silver phosphate