The Relationship Between The Morphology Of Titanium Dioxide And The Relationship Between Oxygen Deficiency And Photocatalytic Degradation Properties

Titanium dioxide,as one of the most important transition metal oxide,offers great potential for environmental protection.Firstly,through a systematic investigation,this work would provide the relationship between catalyst structure and catalytic performance of the degradation of Direct Blue.Secondly,we analyzed the kinetic studies of direct blue photodegradation over flower-like TiO2 under ultraviolet light illumination.Finally,oxygen deficient Ti02 photocatalyst was prepared by the method of hydrogenation reduction.Furthermore,we illuminated the relationship between oxygen concentration and photocatalytic activity using H2-TPR technology at the first time.The main research contents are described as follows:Part 1:Morphological effect in photocatalytic degradation of Direct Blue over mesoporous Ti02 catalysts.Four types of anatase Titanium dioxide catalysts with a slice-,bipyramids-,daisy-,and sphere-like morphologies were prepared by hydrothermal methods and well characterized by a serial of characterization techniques.Through evaluating the photo-catalytic performance over four different morphologies TiO2,it was possible to illustrate the structure-performance relationship of degradation of Direct Blue.The results show that TiO2 with different shapes possess varies catalytic degradation efficiency.And the daisy-like TiO2 catalyst exhibited excellent catalytic performance for the degradation of Direct Blue.UV-vis spectrum studies provided a direct evidence for the morphologic dependencies.The difference of the band gaps originating from the morphologies,is the main factor affecting the photocatalytic activityPart 2:Kinetic studies of Direct Blue photodegradation over flower-like Ti02The kinetics of photocatalytic oxidation reaction for Direct Blue solution was studied by using flower-like Ti02 under the irradiation of ultraviolet light.A series of possible affecting factors were studied,including pH value,the additive amount of catalyst and H2O2,and with or without Ag modification.The kinetics analysis found that the process of photocatalytic degradation reaction obeys the rule of a pseudo-second order reaction kinetic model with high regression coefficients(R2).It has been demonstrated that the initial concentration and its related factors have influenced the photocatalytic degradation efficiency and corresponding kinetic parameters.And the kinetic parameters k is increasing with the degradation efficiency.Part 3:Investigation on the enhancement of photocatalytic degradation of Direct Blue towards oxygen defect.In the photocatalytic reaction,poor photocatalytic activity is attributed to the low separation efficiency of carriers and narrow wavelength range of light absorption.The method of hydrogenation reduction was used to prepare colored TiO2 with oxygen vacancies,narrow the valence band’s width,promote photo-generated charge separation and migration rates,and improve photocatalytic efficiency.The samples with different oxygen vacancy concentrations were obtained by controlling the reduction temperatures.The higher photocatalytic activities over colored TiO2 were observed under the ultraviolet light irradiation.While,it was found that the Direct Blue can be degradated effectively over hydrogenated Ti02 under the visible light.The concentration of oxygen vacancies was quantitatively studied by using H2-TPR,and the relationship between the concentrations of oxygen vacancy and the photocatalytic activities was established.Under this condition,the visible photo-catalytic activities increased first and then remained stable with the total oxygen concentration rising.More importantly,the oxygen vacancy implanted on the surface can be the efficient method to improve photocatalytic performance.