Study On The Photoelectricity And Photocatalysis Properties Of Bi₂Ti₂O₇?Bi₄Ti₃O₁₂/TiO₂ Heterostructure Nanotube Array

TiO₂,as a cheap,environmental and commercial semiconducting material,has been attracting the attention of scientists.However,TiO₂ is not enough useful in the field of photocatalysis and photoelectric,because of its large energy gap and rapid carrier recombination.In order to solve the above problems,highly ordered TiO₂-nanotube arrays were prepared via the two-step anodic-oxidation method.They are high crystallinity,have large specific surface area and smooth surface,as well as show the photoelectric properties.Then,using a hydrothermal reaction,the functional heterostructure including Bi₂Ti₂O₇ and Bi₄Ti₃O₁₂ was assembled on TiO₂-nanotube arrays.The functional heterostructure improve the energy band structure,reduce the carrier compound,and enhance photocatalysis and photoelectric properities.Our results of research are:1.The irregular surfaces of these samples needed to be improved via two-step anodization.This anodization led to the formation of self-assembled,ordered TiO₂ nanotubes with smooth walls and mouths.The first step of the anodization thoroughly cleaned impurities from the titanium surfaces;meanwhile,the sunken mark promoted the directed growth of the nanotubes in the second step of the anodization.2.Bi₂Ti₂O₇ and Bi₄Ti₃O₁₂ heterostructure was assembled by hydrothermal reaction.From the growth mechanism of the heterostructure,we concluded that the size and density of the bismuth-titanate heterostructure was determined by the hydrothermal temperature and that the morphology was determined by the pH value of the reaction.3.Solar cells with working electrodes consisting of a transparent platinum electrode and titanium foil were tested under illumination.Under optimum conditions,compared to Sample 0,the short-circuit photocurrent of Sample 9 increased 2,5-fold to 3.46mA/cm2,and the power-conversion efficiency increased 2.3-fold to 1.33%.4.A unique characteristic of a ferroelectric photovoltaic device is the switchable polarization of the ferroelectric material,resulting in a switchable photovoltaic.Most importantly,compared with Bi₂Ti₂O₇,the Jsc and PCE of the samples were further improved due to the ferroelectric properties of Bi₄Ti₃O₁₂.This result,based on using ferroelectric-film layers with strong polarization and high carrier density,may be highly desirable to improve the PV efficiency and for other optoelectronic applications.5.We research the catalytic ability of ultraviolet light of Bi₂Ti₂O₇ and Bi₄Ti₃O₁₂ heterostructure.The results show that the heterostructure can promote transport process of photoproduction carrier,accelerated the decomposition of organic matter.6.In this paper,a preliminary study of bismuth titanate heterostructure was put forward.The band bending which introduced by bismuth titanate heterostructure promote transport process of photoproduction carrier,increases the lifetime of the carrier.In addition,the built-in electric field which produced by ferroelectric accelerate the separation of the carrier.