Synthesis And Property Adjustment Of One-dimensional Molybdenum Oxide Nanomaterials

With the development and advanced research in nanoscience and nanotechnology,one-dimensional(1-D)nanomaterials have attract widely interesting due to their unique property and broad foreground in application.It is important to control the geometry,dimension,composing,crystal structure and properties of the 1-D nanomaterials and investigate the relationship between structure and properties by studying their growth mechanism,which is useful to achieve the goal of synthesizing functional materials by human willing.Because of the potential application in many fields,such as lithium ion secondary batteries,catalysts,sensors, electrochromic and optical materials,molybdenum oxide and molybdate have been more paid attention to.In this dissertation,one dimensional molybdenum oxide nanomaterials were chosen as the object of study.Modern testing methods were used to study the structure and properties of 1-D molybdenum oxide nanomaterials,and the approach of property adjustment was investigated.The obtained main results are as follows:(1)MoO₃ nanobelts were synthesized via the simple hydrothermal reaction from stable sols prepared by two different methods without template and catalyst. The as-synthesized samples consisted majority of single-crystal orthorhombic MoO₃ nanobelts.The growth mechanism of MoO₃ nanobelts was investigated by studying the influence of hydrothermal temperature,reaction time and precursor concentration on the structure and morphology of the product.The electrochemical property of nanobelts was studied,higher capacity and more stable cycling performance of MoO₃ nanobelts were obtained compared with these of bulk one.(2)Vapor phase reduction,solution in-situ reduction and sol-solvent thermal methods were used to synthesize different morphology 1-D MoO₂ nanomaterials, and the possible growth mechanism was investigated.(3)Molybdenum oxide nanotubes were synthesized with the assistant of HDA (hexadecyl amine-hydrochloride)as surfactant.The crystal of morphology were characterization and the chemical composition of(MoO₃)₀.77(HDA)₀.23 was obtained. The "rolling" process was built to explain the growth mechanism of tube-like shape.(4)The MoO₃ nanobelts were lithiated successfully by two methods(direct and indirect).The structure and morphology of nanobelts were also kept after lithiation, and the electrochemical property such as cycling performance for lithium battery were greatly enhanced compared with pure one.Transport measurement showed that the conductivity of a lithiated MoO₃ nanobelt(10^-2S/cm)is increased by close to two orders of magnitudes compared to that of a non-lithiated MoO₃ nanobelt(10^-4S/cm), suggesting that Li⁺ ions were introduced into the MoO₃ layers during lithiation.(5)Mental ions were introduced into molybdenum oxide to prepare the 1-D molybdate nanomaterials.Micron-size spindle-like ZnMoO₄ was synthesized by sol-hydrothermal method,the particle size was controlled in nanoscale successfully by microemulsion system,and NaZn₂OH(MoO4)₂(H₂O)and CaMoO₄ nanorods were obtained.Different PL peaks of the NaZn₂OH(MoO₄)₂(H₂O)nanorods was observed under different excitation wavelengths,and more excellent PL property of CaMoO₄ nanorods was observed compared with that of bulk materials under the same excitation wavelength.