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Preparation Of Ordered Mesoporous Titanium Dioxide-carbon Nanocomposites And Their Photoelectrochemical Performance

Posted on:2013-11-19Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y X GuoFull Text:PDF
GTID:1261330422480183Subject:Materials Physics and Chemistry
Abstract/Summary:PDF Full Text Request
TiO2materials are expected to play an important role in solving many serious challenges due toits good characteries of powerful oxidation strength, high chemical stability.But in the practicalapplication, there existed many problems such as poor electrical conductivity, weak thermal stabilityand wider band gap. In order to solve these issues, this work carried out the basic and applied researchto explore the preparation of the new structure of the catalyst support and resolve the mechanism ofthe how to improve the activity and the stability of the catalyst.In this work, we prepared orderedmesoporous titanium dioxide-carbon composites by organic-inorganic self-assembly method aspolymer materials as the carbon source, Trebloc surfactant as a structure directing agent. To enhancetheir photoelectrochemical activity, highly graphitized carbon material such as carbon nanotubes,Graphene oxide is introduced into the composites.Meanwhile, tungsten oxide is also added todecrease the band gap of the composite.The main contents include:At first, we have designed a novel catalyst with highly ordered mesoporous structure. A highlyordered mesoporous titanium oxide-carbon composite material is synthesized by organic-inorganicself-assembly with tetrabutyl titanate as precursor, phenolic resin as a polymer source, F127as thestructure directing agent. The introducing of the carbon as a "binder" to "bond" together prevented thetitanium oxide grain growth during the heat treatment. This combined the carbon with strong thermalstability and titanium oxide with the highly photocatalysic performance, preventing the collapse of themesoporous skeleton structure of Titania, effectively improving the oxidation of methanol.Meanwhile, combined the electro-catalytic performance of platinum and the photocatalytic activity oftitanium oxide, to research its behavior of methanol oxidation to joint the DMFC/photovoltaic cellssystem.Platinum is deposited on the surface of the electrode, which can improve the electricalconductivity, increase the active points of the electrodes and separate the electron and hole.In order to enhance the photoelectric-chemical performance, sodium polystyrene sulfonate (PSS)modified carbon nanotube was chosen to order mesoporous Titanium dioxide-carbon-carbonnanotube composite material. The experiments showed that with the content of carbon nanotubes andincrease of the temperature, existed the “mixed crystal effect”, enhance the thermal stability (700degree) and photocatalytic performance of the material due to higher crystallization degree, transmission of the electronic and sharper electron-hole separation, thereby increasing the overallphoto-response current from0.4μA to7μA..To further improve the electrical conductivity, we synthesis the highly orderly mesoporoustitanium dioxide-carbon-graphite oxide composite materials by organic-inorganic self-assemblymethods, with the graphite oxide as raw material.By appropriate methods to effectively improve thedispersion of graphite oxide to find the right TiO2modification process. Tests show that orderedmesoporous titanium-carbon-graphite oxide composite material better methanol oxidationperformance after the irradiation of ultraviolet light excitation, wherein, the doping amount of thegraphite oxide with8%and the calcining temperature with900℃is chosen as the best modifiedconditions, photocurrent increased to13.2μA.Silicotungstic acid is doped in the mesoporous titanium dioxide-carbon material to furtherimprove the photoelectrochemical properties of titanium dioxide material,. XRD and TEMcharacterization of the phase structure showed that the composite material has high orderedmesoporous structure.Current-time measures displayed that the materials has the optical and electricalproperties when WO3doping amount is8%.More important, in the Current-time measures process, itwas observed that the current value of the samples calcined under air atmosphere is no suddentransitions to the minimum value but after a period of decreased slowly when the removal of theultraviolet light irradiation, WO3electronic storage capacity is taken into account the energy storageconceptWe deposited nickel hydroxide material by galvanostatic deposition in TiO2electrode materialsto research energy storage properties of TiO2-Ni (OH)2composite materials,. the charge and dischargecurves show that the explode with1.5mA current deposition of nickel hydroxide displayed the bestdioxide material storage performance, Charge and discharge curves proved that TiO2-Ni (OH)2composite materials has the energy storage performance, layed the foundation for further study of thetitanium dioxide material in the dark environment.
Keywords/Search Tags:Mesoporous materials, titanium dioxide, Photoelectrochemical, carbon nanotubes, graphite oxide
PDF Full Text Request
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