Study On Synthesis And Properties Of TiO₂/BiVO₄/SiO₂ Thin Film

With the research and development of photocatalysis technology,its application in the environment more and more get people’s attention.Good stability,high photocatalytic activity of TiO₂ has attracted wide attention of scholars,but the higher the forbidden band width of 3.2 eV,only to ultraviolet light absorption,limiting the utilization rate of the sun’s rays.Monoclinic phase BiVO₄ as a new type of semiconductor material,has good visible light responsivity,the forbidden band width is 2.4 eV,but pure BiVO₄ conduction band edge location of the electric potential at 0 v,the photoproduction electronics is not easy to combine with oxygen in the air to generate active substances,causing the accumulation of the electron in the catalyst surface,increases the chances of recombination between electrons and holes,thus greatly reduces the BiVO₄ in visible light photocatalytic activity.Studies showed that two kinds of semiconductor composite material had good visible light catalytic activity.Powder of photocatalyst is easy to deactivation,recycling and other shortcomings,its application is restricted.Film class of photocatalyst has the advantages of good stability,strong acid or alkaline and recycling easy,is widely used in our daily life.The self-cleaning materials to obtain good development.Self-cleaning materials is to break down organic matter by light or super hydrophobic and super hydrophilic realize self-cleaning function,in architecture,such as traffic,new energy industry has important application prospect.This paper includes the following several parts:（1）Used common glass as substrate,the different coated number of TiO₂ thin film and TiO₂ thin film used diethanolamine were prepared by sol gel method.Used X-ray diffraction（XRD）,scanning electron microscope（SEM）and Uv-Vis spectrum analysis of different number of coated film crystal structure,morphology and ultraviolet-visible absorption ability.At the same time,through the degradation of methylene blue and the determination of contact Angle inspects the photocatalytic activity of the film and self-cleaning ability.BiVO₄ powder was prepared by rhydrothermal method;the influence of pH of BiVO₄ crystal was studied.It was concluded that under acidic conditions is advantageous to the monoclinic phase BiVO₄ generated.Take the base of common glass,the BiVO₄ film with the different coating number were prepared by sol gel method,used X-ray diffraction（XRD）,scanning electron microscope（SEM）and Uv-Vis spectroscopy investigation film crystal structure,morphology and ultraviolet-visible absorption ability.At the same time,through the degradation of methylene blue and the determination of contact angle inspects the photocatalytic activity of the film and self-cleaning ability.（3）TiO₂/BiVO₄ film was prepared by sol-gel method.Used X-ray diffraction（XRD）,scanning electron microscope（SEM）and Uv-Vis spectroscopy investigation film crystal structure,morphology and ultraviolet-visible absorption ability.At the same time,through the degradation of methylene blue and the determination of contact angle inspects the photocatalytic activity of the film and self-cleaning ability.With a single TiO₂ thin film and the photocatalytic activity of BiVO₄ film and self-cleaning capacity comparison,found that TiO₂/BiVO₄ film than a single Ti O₂ thin film and BiVO₄ film has higher visible light catalytic activity and excellent self-cleaning ability.（4）The SiO₂ thin film and TiO₂/BiVO₄/SiO₂ thin filmswere prepared by sol-gel method.Used X-ray diffraction（XRD）,scanning electron microscope（SEM）and Uv-Vis spectroscopy investigation film crystal structure,morphology and ultraviolet-visible absorption ability.At the same time,through the degradation of methylene blue and the determination of contact Angle inspects the photocatalytic activity of the film and self-cleaning ability,and compared to TiO₂/BiVO₄ film,found that the photocatalytic activity decreases,but better than the single TiO₂ film and high photocatalytic activity of BiVO₄ films,self-cleaning ability is excellent.