Synthesis,Characterization And Properties Of Gallium Oxide And Zinc Gallate

Inorganic materials with novel architectures are useful for many potential applications.Among these materials,gallium oxide and its oxygenates in the form of nanoparticles,nanorods,nanobelts,etc.have always received additional attention.The reason is not only thousands of nanostructures have been constantly prepared,but also nano-structure-based nanodevices can be accepted by the market.The application and popularity of gallium oxide and its oxygenates in optics,electronics,magnetism,gas sensing and field emitting provide expansive space for the development of inorganic materials.Gallium oxide and zinc gallate,as one of the most important types of semiconductor,not only have been extensively studied,but also are potential photocatalysts for the treatment of waste water.However,the existing synthes is methods have long production cycle,irregular morphology,heavy aggregated and poor dispersion.And these make its performance in the application of photocatalysis be significantly impaired and its popularity in market practitioners be hindered.In order to improve its performance significantly,the preparation methods of the materials are studied.In this thesis,Ga₂O₃ and ZnGa₂O₄ was taken as the main research object.By investing its morphology and phase,we had advanced a examination of growth mechanism.In order to find a simpler method for the preparation of materials with strong photocatalytic activity,we should control the effect of various factors.The detailed contents are as follows:?1?Ga₂O₃ microcrystals with pore structure were successfully synthesized by a novel s imple precursor thermal decomposition approach.XRD,SEM,EDX,Uv-vis were used to characterize the structure and properties of Ga₂O₃.The corresponding results revealed that the obtained samples were monoclinic Ga₂O₃ blocks having uniform structure,and the average pore diameter on the surface were about 30 nm.The band of Ga₂O₃ was 4.13 eV,which was about 0.77 eV smaller than the theoretical value.The influence of high temperature and high pressure during the preparation of Ga₂O₃ made the crystallinity,morphology and oxygen vacancy different,and partly overlap between the conduction and valence band.In addition,the prepared Ga₂O₃ showed strong photocatalytic activity in the degradation of congo red.There might be a good reason for that: highly reactive substances catalyzed by Ga₂O₃ were further reacted with the dye and destroied its conjugate system and C-N bond.?2?Ga₂O₃ sphere nanoarchitectures were successfully prepared via a solvothermal route using gallium nitrate as gallium source and the mixed of oleic acid,ethanol and water as solvent.A serious experiments showed that the optimal conditions preparing Ga₂O₃ were that VH₂O: VEA = 1:4,the reaction temperature was 150 ?,the reaction time was 8 h.Oleic acid had an important role in the controlled growth and morphology.Based on these experiments,a possible mechanism of the Ga₂O₃ sphere nanoarchitectures was proposed.Furthermore,the as-obtained Ga₂O₃ sphere nanoarchitectures had a good photocatalytic effect for safranine T.The degradation rate reached to 92% after irradiation for 120 min.The reason was that Ga₂O₃ had a higher rate of charge separation.?3?Rod-like ZnGa₂O₄ microcrystals was synthesized by a facile hydrothermal method.Ga₂O₃ microcrystals were synthesized by a novel simple precursor thermal decomposition approach first.Then,rod-like ZnGa₂O₄ microcrystals were successfully synthes ized by a facile solvothermal route using Ga₂O₃ as a base material and zinc carbonate as zinc source.It was found that the as-prepared ZnGa₂O₄ had a spinel-type phases with a diameter about 300 nm,and the average length in the range of 1 to 2?m.Furthermore,the proportion of Zn²⁺/Ga³⁺,reaction time and p H were investigated,among which the appropriate amount of NaOH played a key role.A test on its photocatalytic degradation effect showed a degradation rate of 90% and 83% after irradiation for 30 min.?4?At a low temperature,ZnGa₂O₄ and Zn_1-xCo_xGa₂O₄ were successfully prepared by using ZnO,GaCl₃ and CoCl₂·6H₂O as reactants.The phases and morphologies of the products were characterized by a variety of instruments.It was interesting to found that Co could affect the shape and performance of the materials.Because Co-doped ZnGa₂O₄ was favorable for the interfacial separation of electron-hole pairs and enable to have better photocatalytic performance than monomers.It was found that the key to the formation of ZnGa₂O₄ nanoparticles cubes was the surfactant CTAB.By using CTAB as a soft template in the system,we could control the morphology of nano-materials.