Preparation Of Mesoporous Titanium Dioxide Using Block Copolymers As Templates

With the reduction of resources such as oil,coal and natural gas,the increasing demand for energy and the intensification of environmental pollution,energy conversion and storage technologies?such as dye-sensitized solar cells?DSCs?,fuel cells,lithium-ion batteries?and photocatalytic degradation of organic pollutant technology are highly valued and made significant progress,but there are still many scientific problems still hindering the development of such technology.Mesoporous TiO₂ is a good electrode material,its performance can determine the photoelectric conversion efficiency of solar cells;nano-TiO₂ can also be used as a photocatalyst,which has excellent catalytic degradation effect.Therefore,the study of titanium dioxide nano-materials to improve the preparation method has become a hot spot.In this paper,F-doped TiO₂ nanoparticles?F-TiO₂?were prepared by using hydrothermal method through hydrolysis of TiCl₄,precipitation,oxidation,complexation and refluxing crystallization process.In this work the factors influencing the synthesis of titanium dioxide nanoparticles were explored,and the best synthesis scheme was obtained.It was found that F-doped TiO₂ nanoparticles showed excellent photocatalytic properties.Next,the organic-inorganic hybrid titanium dioxide film was synthesized by sol-gel method using the block copolymer F127 as the template,tetraisopropyl titanate?TTIP?and TiCl₄ as inorganic precursors.After the block copolymer was removed by calcination,mesoporous TiO₂ were obtained.In addition,mesoporous TiO₂ were prepared by co-assembly of F-doped titanium dioxide nanoparticles with F127.?1?F-doped TiO₂ nanoparticles: The anatase TiO₂ nanoparticles were synthesized through a hydrolysis TiCl₄ at alkaline condition to form titanium hydrate precipitates,and then the titanium hydrate precipitates were subjected to a peptizing,complexing and refluxing process at 100 °C and atmospheric pressure.No surfactants or capping agents are used in the synthesis process.The results show that the molar ratio of NaF/TiCl₄ plays an important role in the formation of anatase F-TiO₂ nanoparticles.F-ions can enter the lattice of TiO₂ and adsorb on the surface of TiO₂.F-TiO₂ nanoparticles are the photocatalytic degradation catalysts for the degradation of methylene blue dyes under UV and visible light irradiation.At the same time,other factors affecting the morphology and properties of titanium dioxide nanoparticles were discussed,including the formation temperature,concentration and other halogen elements.The optimum synthesis temperature was 100 °C and the molar ratio of NaF/TiCl₄ was 4/1.?2?Preparation of mesoporous TiO₂: The micelles of block copolymer F127 in ethanol was used as a template,and the sol-gel formed by slow hydrolysis of titanium dioxide precursor TTIP in concentrated HCl or TiCl₄ in ethanol was used as inorganic component.The influencing of the molar ratio of F127/inorganic precursors,solvent evaporation rate,sol-gel storage time,colloidal formation temperature,aging time and calcination method on the formation of mesoporous TiO₂ was investigated.The optimum molar ratio of F127/inorganic precursors was obtained.The appropriate increase in the temperature of the mixture solution and reduction the evaporation rate of the solvent,are conducive to the synthesis of ordered mesoporous TiO₂.At the same time,F-doped TiO₂ nanoparticles were coassembled with F127 to prepare mesoporous titania nanomaterials.The resulting mesoporous TiO₂ has an average pore size of 8.57 nm and a pore volume of 0.45 cm³ / g.