Preparation And Properties Of Molybdenum Disulfide-based Composite Photocatalysts

In recent decades,semiconductor photocatalysis technology,as an important advanced oxidation technology,has shown great development potential in many fields(e.g.,environmental remediation).However,traditional semiconductor materials always have wide bandgap and serious photogenerated electron-hole pairs recombination,which will limit the availability of photocatalysis.The combination of localized surface plasmon resonance(LSPR)effect with photothermal effect will further optimize the light absorption and carrier separation efficiency of photocatalysts,which is one of the most effective methods to optimize the photocatalytic performance.There are a large number of reactive unsaturated sulfur atoms on the edge of defective molybdenum sulfide(MoS₂)nanosheets.These sulfur vacancies can boost photocatalytic reactions and retard the lifetime of photogenerated electron-hole pairs.Moreover,MoS₂ has excellent photothermal effect,which can improve the near infrared light absorption ability and photocatalytic performance of photocatalyst.The local heating effect and“hot electrons”generated by LSPR effect can further improve the photothermal effect and the spatial transfer of photoinduced charge carriers of MoS₂-based photocatalysts.In this paper,WS₂/WO_3-x/MoS₂ and Ag/?-Fe₂O₃/MoS₂ composite photocatalysts have been prepared.Their photocatalytic performance has been measured by photocatalytic degradation on 2,4-dichlorophenol(2,4-DCP)and other organic pollutants under visible light and visible-near infrared light.The research content of this paper is mainly divided into the following two parts:(1)WS₂/WO_3-x/MoS₂ composite photocatalyst with wide spectral response has been prepared by hydrothermal and calcination-assisted methods.WO_3-x with LSPR effect acts as a bridge to connect the sulfur defective MoS₂ nanospheres and WS₂ quantum dots,forming tandem dual Z-scheme heterojunctions.The degradation rate on 2,4-DCP of WS₂/WO_3-x/MoS₂ photocatalyst is more than 96%under visible and visible-near infrared irradiation.Under the synergistic effects of photothermal effect,LSPR effect,Z-scheme heterojunction and sulfur defects,the prepared WS₂/WO_3-x/MoS₂ ternary photocatalyst shows enhanced near infrared absorption and photocatalytic degradation performance.(2)Ag/?-Fe₂O₃/MoS₂ composite photocatalyst with wide spectral response has been prepared by hydrothermal and chemical deposition methods.Firstly,?-Fe₂O₃ polyhedron templates are prepared by hydrothermal method.In the recombination process with MoS₂,?-Fe₂O₃ polyhedrons collapse into nanoparticles,which will disperse in the hollow flower-shaped polyhedral MoS₂ structure.Then,Ag nanoparticles will be loaded on the surface of?-Fe₂O₃/MoS₂ by chemical deposition method to form Z-scheme heterojunction.The prepared Ag/?-Fe₂O₃/MoS₂ composite photocatalyst can degrade almost all 2,4-DCP under visible and visible-near infrared light.Under visible light,the salicylic acid degradation rate is over 98.1%.Under the synergistic effects of photothermal effect,LSPR effect,Z-scheme heterojunction,sulfur defects,and heterogeneous Fenton-like reactions,Ag/?-Fe₂O₃/MoS₂ composite photocatalyst has shown excellent photocatalytic degradation performance.