Controlled Synthesis And Application Exploration Of Titanium Oxide And Its Carbon Composite Nanomaterials

Titanium oxide and its carbon composite nanomaterials, including self-assembled urchin-like TiO2-C micro-nano composites, titanate nanocrystals, are studied. Application of the urchin-like structure in lithium ion battery and the inner relationship between the structure and property are also discussed.A new type of self-assembled TiO2-C micro-nano composites is prepared via a one-step solvothermal method, in which hydrolysis of titanium tetrachloride, carbonation of D-glucose and esterification occur simultaneously. Series of comparative experiments are performed to study the affecting factors, such as titanium precursor species and its concentration, alcohol species, solvothermal temperature and time, compactness, glucose addition, calcination temperature, crystal seeds and surfactant. Moreover, TiO2@C nanoparticles are obtained in the above experiments. Urchin-like structure is confirmed by SEM, TEM, Raman and XRD characterizations. TiO2 nanorods with the diameter of 10-20 nm are packed closely around the center of the structure with carbon distributed homogeneously between the interspace of the nanorods. The diameter of the microspheres ranges from 500 nm to 10μm. Electrochemical measurement shows a good capacity and cycle performance of the urchin-like structure. Cycled between 1 and 3 V at 30 mA·g-1, the sample annealed at 600℃(carbon content 20 wt%) demonstrates a first discharge capacity of 335 mAh·g-1. Up to 0.78 Li+ is inserted reversibly into per TiO2. When the sample annealed at 700℃(carbon content 1.7wt%) is cycled between 0.1 and 3 V at 20 mA·g-1, the first and 70th discharge capacity are 263.7 mAh·g-1 and 244.6 mAh·g-1, respectively.Titanate nanocrystals are synthesized through hydrothermal and solvothermal methods. By controlling alkalinity, solvent species and volume, and TiO2 addition, well-crystallined titanate nanosheets and nanotubes are prepared. Alkalinity is the key factor of morphology, so addition of low-boiling point and inert organic solvents helps to the formation of nanotubes. Rock-like LiTiO2 nanosheets are obtained from titanate nanocrystals through ion exchange with LiOH. Further study will be taken on its property and application.