Preparation And Photocatalytic Properties Of TiO₂/BaTiO₃ Composite Photocatalyst

The high recombination efficiency of photogenerated carriers is the main problem faced by TiO2 photo catalyst.The piezoelectric field in nanowires can provide energy for carriers transport,and improve photocatalytic performance,when TiO2 nano particles were combined with piezoelectric nanowires array.Therefore,in this paper,BaTiO3 nanowires array was prepared by hydrothermal method,with sodium titanate nanowires array as precursor.TiO2/BaTiO3 composite photocatalyst was obtained by hydrolysis of butyl titanate(TBOT).The microstructure and phase composition of the samples were characterized by EDS,XRD,SEM and TEM.The photocatalytic properties of Samples were studied under different conditions(ultraviolet light,ultrasound,ultraviolet light+ultrasound).The photoabsorption of samples was studied using UV-Vis DRS.By degrading methyl orange,the improvement of photocatalytic performance with piezoelectric assistance was preliminarily analyzed.Rutile-TiO2 as Ti source formed on the surface of Ti sheet by high temperature oxidation,and NaOH as mineralizer,Na4Ti3O8 nanowires array was prepared by hydrothermal method.The effects of oxidation time,hydrothermal temperature,hydrothetrmal time and alkali concentration on the morphology of Na4Ti3O8 were studied.Then,the Na4Ti3O8 nanowires array was given a heat treatment.The experimental results showed,the size of the nanowires array is neat(length is about 40 m,diameter is about 175 nm),the density is moderate(the gap between adjacent lines is about 560 nm),and the orientation is good,when the oxidation time is 8 h,the hydrothermal condition is 210 ?,10 h,12 M and the heat treatment temperature is 800 ?,Using sodium titanate nanowires array as precursor,and Ba(OH)2 as Ba source,BaTiO3 nanowires array was prepared by hydrothermal method.The effects of hydrothermal temperature,time and concentration of Ba(OH)2 on the pattern and phase of the sample were studied.The experimental results showed,when the reaction condition was 210 ?,12 h,0.02 M,the nanowires array is tetragonal BaTiO3,and inherits the morphology of precursor.TiO2/BaTiO3 composite photocatalyst was prepared by hydrothermal method using BaTiO3 nanowires array as basis.The effects of mass ratio of BaTiO3 to TBOT on the morphology,phase and photocatalysis properties of the product were studied.The experimental results showed,the distribution of anatase-TiO2 on the surface of BaTiO3 nanowires array is uniform,when the mass ratio of TBOT to BaTiO3 is 1:1.The photocatalytic efficiency(67.7%)of methyl orange in ultrasound+ultraviolet light is higher than that(55.4%)under ultraviolet light.The photocatalytic performance can be improved obviously by introducing ultrasound into the photocatalytic reaction.The piezoelectric photocatalytic mechanism is,that the ultrasound drives polarization electric field to change periodically,and controls the directional shift of the carriers,then photocatalytic performance of materials is improved.