Synthesis And Proderties Of Hierarchical Micro-/Nanostructures Materials

Among various metal oxide semiconductors, titanium dioxide (TiO2) has been extensivelystudied because of its outstanding advantages such as non-toxicity, stability, corrosionresistance, and low cost. These advantages mean that TiO2has been widely applied in the fieldsof air and water remediation, pesticide degradation, and selective synthesis of chemicals.Recently, inorganic fuctional materials with hierarchical micro-/nanostructures have attractedintensive interest for the structure joined the intrinsic effect of bulk materials with thenano-effect of nanomaterials and produced many combinatory effects. Hierarchicalmicro-/nanostructures have been show attractive superiority in energy conversion, such as solarcells and photocatalytic hydrogen generation, energy storage, such as lithium ion batteries andsupercapacitor, sensor, catalysis, water treatment and so on. Therefore, exploration ofreasonable synthetic methods for controlled construction of hierarchical micro-/nanostructuresmaterials via a simple, practical and reliable chemical route is an intensive and hot researchtopic. In this thesis, we attempted to synthesize hierarchical micro-/nanostructures by newchemical method, due to its low cost and potential advantage for large-scale production. Thephotocatalytic and superhydrophobic properties of the obtained structures as well as theralations between their structures and performances have been studied. Detailed researchcontents are summarized as following:1. Preparation and Photocatalytic properties of TiO2@@SiO2/PVA Nanofiber membranewith Hierarchical Micro-/NanostructuresNanovoid core(TiO2)/shell(SiO2) nanoparticle (TiO2@@SiO2) was fabricated by usinghydrothermal method and unique sol-sel method, there was a2-3nm nanovoid layer betweenthe TiO2core and the silica layer, Thus this particular core-shell structure makes itpossible to coated photocatalyst on organic carrier. Then by using coaxial electrospinningmethod, TiO2@@SiO2/PVA nanofiber membrane with hierarchical micro-/nanostructures wassynthesized. electrospinning voltage, collector distance, flow rate and PVA concentration is very important to the sysnthesis of PVA nanofibers and TiO2concentration is the key factor tothe preparation of TiO2@@SiO2/PVA nanofiber membrane with hierarchicalmicro-/nanostructures. Thermal gravimetric analysis indicated that the loaded amount ofTiO2@@SiO2was reached43%. The result shows that the photocatalytic activity ofTiO2@@SiO2/PVA nanofiber membrane with hierarchical micro-/nanostructures is two and ahalf times higher than P25TiO2nanoparticles.2. Controlled Synthesis of Hierarchical TiO2/CNTs Micro/Nano-structures with TheirEnhanced Photocatalytic ActivityA novel carbon nanotubes (CNTs)-dispersed route was used to prepare high-activitytitanium dioxide nanoparticles (TiO2). By using carbon nanotubes as support and glucose as abinder, it is advantageous to obtain hierarchical TiO2/CNTs micro-/nanostructures, then,TiO2/CNTs was calcined in air to obtain the highly dispersed TiO2nanoparticles. carbonnanotubes，glucose solution and reaction time is very important to the sysnthesis of hierarchicalTiO2/CNTs micro-/nanostructures, And they also have great effects on the photocatalysisproperties of TiO2Nanoparticles, The photoactivity of TiO2was tested by photodegradation ofRhodamine B. The result shows that the photocatalytic activity of TiO2nanoparticles prepared bythe CNTs-dispersed route is three times higher than that by conventional hydrothermal treatment.3. Fabrication of Superhydrophobic Coatings Based on hierarchical TiO2/CNTsmicro-/nanostructuresThe hierarchical TiO2/CNTs micro-/nanostructures was synthesized by a simple and lowcost method. Lower surface energy and surface roughness are the necessary factors to achievethe phenomenon of superhydrophobic and reaction time have a great effcct onsuperhydrophobic performance of TiO2/CNTs surface, The contact angles and slide angles ofwater are above150oC and below10oC on the TiO2/CNTs surface after modified with (FOTS),and TiO2/CNTs surface has excellent environmental stability. TiO2/CNTs coatings also exhibithigh oil and water separation ability and will have a broad application prospects in industrialoil-polluted water treatments and oil spill cleanup.