Research On The Preparation And Properties Of Titanium Dioxide Nanosheets-based Composites

A large amount of dye wastewater has brought serious pollution to the environment.It is urgent to find effective treatment methods of dye wastewater to solve the problem.As a new green technology,semiconductor photocatalysis has attracted more and more attention with the advantages of low cost,effective degradation of dyes,etc.It has great research value in solving the problem of organic wastewater.As a semiconductor material,TiO₂ has many advantages,such as high chemical stability,low cost,non-toxic and light corrosion resistance.Therefore,TiO₂is considered as a promising photocatalytic material.However,the large bandgap?3.2eV?of TiO₂ restricts its use only to the narrow light-response range of ultraviolet,and electron and hole can easily recombine before they emigrate to the photocatalyst surface,which limits its photocatalytic applications.Therefore,it is necessary to improve the photocatalytic performance of TiO₂ by modifying it.In this study,MTCPP/TNS-rGO nanocomposites and MoS₂/TNS nanocomposites were prepared by hydrothermal method and condensation reflux method.The photocatalytic performance and photocatalytic mechanism of the prepared nanocomposites were studied.The main research contents as following:1.Rectangular ultrathin TiO₂ nanosheets were prepared by hydrothermal method.The size of the nanosheets were about 64 nm×47 nm×4 nm?length×width×thickness?.Graphene oxide?GO?was prepared by modified Hummers method,then rGO-TNS nanocomposite were prepared by hydrothermal method with TNS.The morphology and structure of TNS and rGO-TNS nanocomposites were characterized by scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,etc.2.CuTCPP/TNS-rGO and FeTCPP/TNS-rGO photocatalytic nanocomposites were prepared by sensitizing rGO-TNS with copper meso-tetra?4-carboxphenyl?porphyrin?CuTCPP?and iron meso-tetra?4-carboxphenyl?porphyrin?FeTCPP?.The morphology,structure and properties of samples were characterized by transmission electron microscopy?TEM?,X-ray photoelectron diffraction spectroscopy?XRD?,Raman spectroscopy?Raman?,UV visible spectroscopy?DRS?,photoluminescence spectroscopy?PL?,X ray photoelectron spectroscopy?XPS?method,etc.The photocatalytic performance of samples were characterized by degrading methylene blue?MB?under visible light.After 60 min irradiation,CuTCPP/TNS-rGO and FeTCPP/TNS-rGO degraded 91.1%and 89.2%of MB respectively.The degradation rate was higher than that of TNS and rGO-TNS.The results show that the synergistic effect between MTCPP,TNS and rGO can greatly improve the photocatalytic performance of the materials.In addition,the photocatalytic mechanism of the nanocomposites were also studied and expounded.3.MoS₂/TNS nanocomposites with sheet-sheet nanostructure were prepared by an improved hydrothermal method.The morphology,structure and properties of the samples were characterized by SEM,TEM,XRD,DRS,XPS and PL.The adsorption performance of the catalysts were tested in the dark.The results showed that the adsorption properties of MoS₂/P25 and MoS₂/TNS were better than those of P25 and TNS.After 60 min irradiation,MoS₂/P25 and MoS₂/TNS degraded 90.3%and 99.2%of MB respectively.These results indicated that MoS₂/TNS nanocomposite with sheet-sheet nanostructure had excellent photocatalytic properties.In addition,the photocatalytic mechanism of the nanocomposites were also studied and expounded.In this study,different photocatalytic nanocomposites were prepared by the improved hydrothermal method and condensation reflux method.The materials were characterized by different methods and degrading of MB under visible light.The mechanism of photocatalytic degradation of organic pollutants were studied and expounded.All of these work provide theoretical guidance and applied exploration for the development of efficient photocatalyst to degrade dye wastewater.