Study Of Multiple Anatase Mesoporous Titania

With decreasing non-renewable energy and deteriorating environmental problems, how to develop and utilize clean and renewable energy becomes urgent. As an energy conversion device, solar cells can transform effectively solar energy into electric energy. The electricity energy can be stored as chemical energy and then is released continuously and steadily via Li-ion battery. Mesoporous TiO₂ is one of the best candidates for electrode materials, because of its amazing properties such as large pore volumes, controllable pore sizes, high surface areas, low cost, environmental benignity, good chemical and thermal stability, and excellent electronic and optical properties. It is employed as photo anode materials of dye sensitized solar cells（DSSC）, leading to increase of dye loading and enhancement of efficiency. An improved energy storage capacity is achieved for Li-ion battery for maximized contact area of electrode and electrolyte and shorten diffusion path if it is used as anode material. In this paper, we are focusing on optimizing preparation method of mesoporous TiO₂ materials（MTMs）, developing new methods or unprecedented type MTMs, revealing related formation mechanism and exploring their potential applications in various fields.Monodispersed submicron-sized mesoporous anatase TiO₂ spheres（SMATBs） were prepared via a combined sol-gel and solvothermal process in the presence of hexadecylamine as a structure-directing agent, and followed by a thermal process in air. The effect of reaction temperature and aging time on the TiO₂ precursor formed during sol-gel process was investigated in detail. The SMATBs were used as Li-ion battery negative electrode and gave a discharge capacity of 146.4 mA h g-1 after 200 cycles at 1 C（1 C = 170 mA g-1）, leading to a retention of 85.1%. If they were assembled into DSSC, an overall light conversion efficiency of 6.25% was obtained.Monodispersed submicron-sized mesoporous anatase TiO₂/C composite spheres（MSMATCs） were prepared after a thermal process in argon for the as-prepared TiO₂ which was fabricated via a mixed sol-gel and solvothermal procedure with hexadecylamine as a structure-directing agent. The carbon in MSMATCs is derived from carbonization of residual organic species. Multiple measurement methods indicate that there ¹.5 nm 1.1 wt% carbon layer covers on the surface of basic nanoparticles of MSMATCs. MSMATCs displayed ¹80 mA h g-1 and ¹10 mA h g-1 capacities higher than ¹70 mA h g-1 and ⁹7 m A h g-1 capacities of SMATBs at 1 C and 10 C, respectively.Monodispersed mesoporous anatase TiO₂ spheres（MATBs） were prepared via one-stop solvothermal process using hexadecylamine as a structure-directing agent, and followed by a thermal process in air. The MATBs employed as negative materials for Li-ion battery gave a discharge capacity of 150 mA h g-1 after 50 cycles at 1 C, only a value of 110 mA h g-1 for commercially available 25 nm TiO₂ nanoparticles. Moreover, this versatile method could also be applied to preparation of Li₄Ti₅O₁₂ spheres/sheets. It is worth noting that Li₄Ti₅O₁₂ spheres/sheets still presented a value of more than 100 mA h g-1 even after 500 cycles at 20 C（1 C = 175 mA g-1） if used as negative electrode for Li-ion battery.We developed a simple, mild and in-situ method to prepare mesoporous single-grain layer anatase（MSGLA） TiO₂ nanosheets with 13-30 nm thickness without any additives in methanol on a large scale. The MSGLA TiO₂ exhibited a ⁶0% retention of capacity even after 4000 cycles at 5 C, granting them a promising materials for long-term Li-ion battery.Unique 3-dimentional shuttle-like mesoporous anatase TiO₂ mesocrystals were prepared firstly involving a probable self-assembly process in TBT-methanol system any additives via solvothermal and asubsequent heat treatment. The novel mesoporous TiO₂ mesocrystals kept a contant value of 110 mA h g-1 during 1000 cycles at 1 C, making them be a potential industrial candidate for Li-ion battery.