Preparation,Characterization And Applications In Photoelectro Chemistry Of TiO_x-based Materials

The rapid development of the global economy causes the environmental pollution and energy shortage.The photocatalytic technology and the dye-sensitized solarcell(DSSC)have attracted much attention because of theirunique solutions to both environmental protect and energy supply.TiO2 possessing the rutile(Eg:3.2eV)and anatase(Eg:3.0eV)phases with high activity,is an significant oxide semiconductor in photoelectric area and has important applications in photocatalysis and emerging solar cells.However,TiO2 has a wide band gap and a higher electron-hole recombination rate,which makes the utilization of solar energy insufficient.Three-dimensionally ordered macroporous(3 DOM)structure(also known as inverse opal structure)with open and interconnected macroporous networks,large surface area,and rich surface vacancies,is widely used in the photoelectrochemical field.TiOx with the oxygen vacancy is a series of suboxidation state compound with high conductivity and the chemical inertness in the corrosive medium,of which Ti4O7 possesses the highest conductivity(1000 S/cm),comparable to graphite,and its excellent electrochemical stability is widely concerned in the photoelectric chemistry community.SnOx with the oxygen defects enable the conversion and utilization of solar energy and can be applied to the photocatalysis and multijunction photovoltaic cell.In the thesis,the following workshave been finished:1.The monodispersed PMMA microspheres with different sizes were synthesized via non-emulsion polymerization route,assembled into colloidal crystal template by centrifugation and constant-temperature water bath methods,and then filled with TiO2 precursor by sol-gel process.Changing the soaking times of precursor and the calcination holding time,3DOM-TiOx structure was obtained.And the samples were characterized by SEM and XRD.Using 3DOM-TiOx material as the DSSC anode,the highest powder conversion efficiency(2.3%)of cell was achieved using 300 nm colloidal crystal templatesoaked for 2 times by TiO2 precursor and heated for 2h.2.he porous TiOx was prepared by hydrogen reducing 3DOM-TiOx at 700?,800?,900?,and 100?,,respectively,and characterized by SEM,XRD,nitrogen adsorption-desorption,and UV-Vis spectroscopy.TiOx obtained at the different reduction temperature was applied to photocatalytic degradation of methylene blue(MB)solution and photocatalytic evolution of NOx gas.The results show that the 700? sample has 98%degradation efficiency of MB after irridation for 2h and 55%evolution rate of NOx gas after irridation for 15min,respectively.3.The Ti4O7/Sn5O6 composites with various mass ratio of Ti4O7 and Sn5O6 were prepared by one-step hydrothermal method.Then the Ti4O7/Sn5O6 composites were characterized by SEM,XRD,TEM,XPS,and UV-Vis spectra.The composites were utilized for the photocatalytic degradation of MB solution,reaching as high as 97.5%degradation efficiency after irridation for 4h using the composite with 1:0.8 mole ratio of Ti4O7 and Sn5O6.