Photoelectrocatalytic Activity Of Titania-Based One-Dimensional Nanocomposite

Energy crisis and environmental pollution are one of the greatest challenges in the world at present.Nanosized titania(Ti02)is one of the best promising semiconductor-based photocatalysts,which aroused many scientists' enthusiasm due to its excellent photoelectric and dielectric effect,and good chemical stability.For these reasons,titania has been found a lot of investigation,such as photocatalysis,electrocatalysis,lithium-ion battery,dye-sensitized solar cells,sensors and functional biomaterials.However,there are still many deficiencies in titania.Because the photo-generated electron and hole recombination rate are high,and the light absorption spectra range is narrow,and nanosized material is easy to reunite.How to solve the above problem is one of the hotspots and difficulties in the applications of nanosized titania.In this dissertation,we focus on preparations and applications of nanosized titania and its composites.On one hand,we used one dimensional multiwalled carbon nano tube(MWCNT)as a supporter,and explored the preparation,characterization and photoelectrocatalysis of titania and MWCNT nanocomposite.On the other hand,we used one dimensional nanosized titania,and mainly studied the effects,which was the phase,morphology,microstructure and size,etc of platinum-supported or nitrogen-doped titania nanotube on the photocatalytic activity.Crimp mechanism of titania nanotube was explored.The main points could be summarized as follows.Firstly,titania and MWCNT nanocomposite was prepared by an atmospheric hydrolysis and hydrothermal method,respectively.And the differences of its phase,morphology,structure and performance have been researched systematically.The adsorptive property,photocatalytic activity and electrocatalytic activity of samples have been probed by its microstructural diffence at the same preparation method,but different reaction temperatures and amount of substance ratios between titanium(Ti)element and carbon(C)element.An application of this nanocomposite was developed to direct methanol fuel cell.The morphology,size and photoelectrocatalysis of the nanocomposite have been regulated effectively by controlling the experimental parameter.Results imply that carbon nanotube is one of the excellent supports for titania nanoparticle,and a synergistic effect exists between titania and MWCNT after them composited.All could greatly accelerate the photocatalytic activity and electrocatalytic activity.Secondly,1D fasciculate rutile and rutile@MWCNT nanocomposite were fabricated under sunlight irradiation at room temperature,using titanium tetrachloride as a sole precursor.The fasciculate zone constituted of nanoparticles with a diameter of 4-7 nm,and the growth of fasciculate rutile is oriented,and along the[001]direction of the lattice structure of rutile.In particular,sunlight irradiation plays an important role in the promotion of the formation of the rutile fasciculate zone,and accelerates the hydrolysis of TiCl4 in the sol.The fasciculate zone of phase pure rutile is a low toxicity to blood and hemocompatibility safe.The adsorptive property and photocatalytic activity of fasciculate rutile and rutile@MWCNT nanocomposite had been accelerated,respectively.Thirdly,titania nanotube,platinum-supported or nitrogen-doped titania nanotube were fabricated by a hydrothermal method step by step,using a way of stripping and re-stacking.The way is a dimension-structure conversion technology of 3D?2D?2D,?1D.The formation mechanism of titania was discussed,and it may be crimped by the 1.2 to 2.1 nm thick nanosheet.The hexagonal and squate structures of titania nanotube had been found.Platinum-supported titania nanotube was prepared by platinum-supported titania nanosheet.Platinum was distributed on the surface of the nanotube and the inside of the pipe orifice.The external diameter of platinum-supported titania nanotube was about twice that of without platinum-supported one.This could be related to the effect of nanosized platinum.Titania(anatase)nanosheet with a high percentage of exposed(001)facets was stripped again and crimped to titania nanotube.In this process,a novel structure,which one end is nanotube and other end is nanosheet,was found.Platinum-supported or nitrogen-doped is one of the effective ways of accelerating the photocatalytic activity,respectively.