Exfoliation Of Layered Titanium Dioxide And Electrochemical Properties Of Its Composites

With increasing depletion of global energy, more advanced energy storage devices are intensively demands. Representing a class of energy storage devices, supercapacitors, are of great interest nowadays owing to their high power density and long life cycle. The choice of electrode material crucially impacts the performance of the supercapacitors. Two-dimensional material from exfoliation is becoming a hot topic due to its ultrathin and preparing the other new electrode materials. In this work, We explored the formation mechanism of exfoliation based on the current research situation. And we designed titanium dioxide/nickel aluminum hydroxide and manganese dioxide/titanium dioxide electrode materials on the basis of titanium dioxide nanosheets precursor. The electrochemical performance of the as-obtained materials is to be investigated, which provide basic experimental data and theoretical guidance for the construction of novel electrode materials.Firstly,a large size titanium dioxide layered material with high crystallinity and layered structure degree of order is prepared via high temperature solid phase. Then we put forward the hierarchical insertion method in order to make full exfoliation of the main layered plates.The main preparation process is as following: Firstly, the HCl enlarge the layer spacing by pretreatment process. Then the tetrabutyl ammonium hydroxide ions are substituted for hydrogen ions in the interlayer. The 50 mg TiO2 dissolve in 50mL tetrabutyl ammonium hydroxide ions increase the interlayer space and achieve two-dimensional ultrathin nanosheets successfully. The obtained nanosheets with excellent physicochemical properties can construct the novel electrode material for supercapacitors.Secondly,Ni-Al LDH nanosheets grown on the surface of TiO2 (named as TiO2/Ni-Al LDH) were synthesized via a simple one-step hydrothermal route,which using TiO2,CO(NH2))2 Ni(NO3)2·6H2O and Al(NO3)3·9H2O as the precursor, precipitant, nickel resource and aluminum resource, respectively. In the studies, the electrochemical properties of the as-obtained products were tested under a three-electrode electrochemical system. The composite exhibits higher specific capacitance (807.5 F g-1) than Ni-Al LDH and 70.7%retained specific capacitance after 4000 cycles. The TiO2/Ni-Al LDH composite has good electrochemical properties and great potential in supercapacltor applications.Lastly, we report on the well-designed hierarchical MnO2/TiO2 by crystal growth in situ technique as the electrode material for supercapacitors.The main preparation process is as following: the MnO2 nanoparticles fuse together under crystallographic fusion to form thin layers, then the embryonic MnO2 were self-assembled by these thin layers, finally, porous hierarchical MnO2 grows onto the surface of the TiO2 nanosheets after hydrothermal reaction.We explored the effect of different reaction time on the structure and morphology of the products. The study found that the sample after 24 h growth has better appearance. This structure can provide highly-exposed electrochemically active sites and short diffusion paths for ion and electron transport for the adsorption of Na+, the composite exhibits higher specific capacitance (286.69 F g-1 at a current of 1 A g-1) and has 81.1% retained specific capacitance after 1000 cycles in three-electrode system.