Controllable Preparation And Properties Of Titanium Dioxide Based Nanocomposites

Titanium dioxide has attracted much interest in potential application including energy storage,photocatalysis and so on due to its high chemical and thermal stability,wide band gap etc,.However,the individual titanium dioxide component greatly limit its further application.Nowadays,the synthesis of multi-component TiO₂-based hybrid nanostructures by combining titanium dioxide with other functional components has attracted considerable attention.Such TiO₂-based hybrids can not only combine different functionalities of the individual constituents but also show unique and superior properties different from the individual components,therefore providing potential applications in many fields.In this paper,molybdenum trioxide rods were used as template to prepare TiO₂-based nanocomposites with controllable morphology and modulated component,which were evaluated on catalysis and adsorption application.The specific research contents are as follows:1.The hybrid structure of metallic nanoparticles?NPs?-decorated micro-/nanotubes has the merits of both unique property of metallic NPs and large specific surface area of micro-/nanotubes,which is highly desired for many applications.In this study,Ni NPs decorated porous TiO₂ microtubes with N-doped carbon layer from polydopamine?PDA?are directly synthesized by an extend st?ber method,mussel chemistry and annealing treatment for the first time.In the synthetic process,a shell layer of nickel ion-embedded in polydopamine(PDA-Ni²⁺) was covered on the MoO₃@TiO₂ by nickel ion mediated dopamine polymerization in ammonia solution,resulting in the formation of amorphous TiO₂@PDA-Ni²⁺ hollow microtubes.Notably,the coating of PDA-Ni²⁺ layer and the dissolution of the Mo O₃ cores were easily achieved within one-step reaction,greatly facilitating the synthetic progress.After being annealed in an inert atmosphere,the TiO₂@C-Ni microtubes with anatase,rutile phase of TiO₂ can be obtained.Due to the high coverage of Ni NPs on TiO₂ microtubes with large specific surface area,the as-prepared TiO₂@C-Ni microtubes exhibited excellent performance on adsorption for histidine-rich proteins as well as the reduction of 4-nitrophenol.These results may pave a new avenue on constructing 1D hollow microtubes for potential applications in energy storage,photocatalysis etc.2.TiO₂@MoS₂@Au/Ag/Pd nanocomposites were prepared by hydrothermal reaction,sol-gel process,and in-situ reduction method.Firstly,Mo O₃@TiO₂ was prepared by using Mo O₃ microrods as hard template,and then a layer of MoS₂ nanosheet was grown on the surface of TiO₂ by hydrothermal method.Then high coverage of noble metal nanoparticles?Ag,Au,Pd?was in-situ decorated on the surface of TiO₂@MoS₂ composites without extra reducing agent.Owing to the large specific surface area as well as high density of noble metal nanoparticles,TiO₂@MoS₂@Au/Ag/Pd composites can be used as a catalyst to reduce 4-nitrophenol.The test results showed that TiO₂@MoS₂@Pd showed the best performance on the reduction of 4-NP.3.One dimensional hierarchical TiO₂@Mg SiO₃ composites were prepared by sol-gel process,hydrothermal reaction.Firstly,MoO₃@TiO₂was used as the template,then an extended st?ber was used to obtain the tube-like TiO₂@Si O₂composites.Followed by hydrothermal reaction with Mg²⁺in alkaline solution,the hierarchical TiO₂@MgSiO₃ composites was finally obtained.Moreover,this method can be extended to obtain copper silicate modified TiO₂ microtubes.Owing to large specific surface area,hierarchical MgSiO₃ nanosheets as well as TiO₂ microtubes,the resultant TiO₂@MgSiO₃composites can be used as good adsorbent for adsorption of dye?methylene blue?.