The Study Of Photocatalysis And Photocorrosion Resistance Of TiO₂/CdSe Heterojunctions

Dye wastewater is one of the main water pollution at present.It is an urgent task to solve dye wastewater.As an efficient environmental purification technology,photocatalysis is a new way to degrade dye wastewater.The key of photocatalytic technology is catalysts.The visible light responsive photocatalytic materials based on TiO₂ have received extensive attention,and have been applied in the field of photocatalysis.Among the semiconductors that have been studied more recently,TiO₂ and CdSe have attracted the most attention.After coupling modification,the spectral response range of the TiO₂/CdSe heterojunction is widened,and the separation rate of photogenerated electron holes is improved.However,the photocorrosion of CdSe leads to poor photocorrosion resistance of TiO₂/CdSe heterojunctions.In this paper,the TiO₂/CdSe heterojunction was synthesized by coupling TiO₂ nanotube arrays?TiO₂ NTA?and CdSe nanoparticles.The photocatalytic and photocorrosion resistance of the TiO₂/CdSe heterojunction were improved by compounding with a variety of carbon materials.?1?TiO₂/CdSe/PVA composite films were prepared by spinning Polyvinyl alcohol?PVA?with different thickness on the surface of TiO₂/CdSe heterojunction and dehydrated by heat treatment.The effect of the thickness of PVA film on the properties of TiO₂/CdSe heterojunction was studied.The composite films are composed of anatase-type TiO₂,sphalerite-type CdSe and dehydrated PVA.When the number of spin coatings is 2 layers,the photocatalyst exhibits the best photocatalytic and photocorrosion resistance.The degradation rate of RhB is 58.37%and the protection efficiency is 18.46%.The conjugated C=C structure derived from dehydration of PVA can transmit photogenerated holes and reduce the photoetching process caused by holes.?2?Reduced graphene oxide?RGO?solution was prepared by Hummers method.RGO films with different thickness were spin-coated on the surface of TiO₂/CdSe heterojunction.When the number of spin coatings is 2 layers,the photocatalyst exhibits the best photocatalytic and photocorrosion resistance.The degradation rate of RhB is 62.32%,and the protection efficiency is 50.51%.RGO films play an important role in blocking the permeation of O₂,enhancing the participation of electrons and O₂ in photocatalytic reaction,and inhibiting the photocorrosion reaction caused by electrons and O₂.?3?Composite thin films were prepared by mixing PVA and RGO,in order to construct a continuous conjugate structure,RGO and PVA thin films were spin-coated on the surface of TiO₂/CdSe heterojunction,and TiO₂/CdSe/RGO&PVA composite thin films were prepared.When the mass ratio of RGO to PVA was 85:15,the photocatalyst exhibited the best photocatalytic and photocorrosion resistance.The degradation rate of RhB was 59.06%,and the protection efficiency was 32.86%.RGO&PVA composite films have similar effects as RGO films,and can resist light corrosion by inhibiting the permeation of O₂.