Construction And Performance Of Pyrochloretyped Oxide One-dimensional Nanostructure Photocatalyst

At present,the development of green energy is an effective way to alleviate the global energy shortage and reduce environmental pollution.Hydrogen energy is considered as one of the most promising green energy sources because of its high energy density,pollution-free and abundant resources.Among many semiconductor materials,Lanthanum titanate（La₂Ti₂O₇）with special layered structure and superior stability is considered as a promising photocatalyst.However,the practical application of La₂Ti₂O₇is severely restricted due to its wide band gap,low photo-generated carriers separation efficiencies and limited preparation methods.In addition,there are few reports on the preparation of La₂Ti₂O₇based one-dimensional nanofiber photocatalysts with large aspect ratio and large specific surface area by electrospinning technology.Hence,it is a valuable research topic to construct La₂Ti₂O₇based one-dimensional nanofiber photocatalyst by electrospinning technology and to study its photocatalytic performance.In this dissertation,four kinds of lanthanum titanate based one-dimensional nanofiber heterojunction photocatalysts are prepared by the combination of electrospinning with hydrothermal,fumigation and solvothermal methods,and the structures,morphologies,photocatalytic properties and photocatalytic mechanisms are deeply studied.The details are as follows:1.A novel La₂Ti₂O₇/CdS 1D/0D heterojunction photocatalyst with zero-dimensional Cd S nanoparticles（0D,NPs）modified one-dimensional La₂Ti₂O₇nanofibers（1D,NFs）is designed and prepared by the combination of electrospinning with hydrothermal method.Under simulated sunlight irradiation,the hydrogen evolution rate of the optimal photocatalyst is as high as 6.22 mmol h^-1g^-1,and the photodegradation rates of tetracycline hydrochloride（TCH）and methylene blue（MB）are up to 85.77%and 96.81%in 45 min and 60 min,respectively,showing excellent tri-functional characteristics.2.La₂Ti₂O₇/Bi₂WO₆heterojunction photocatalyst is constructed through the combination of electrospinning with solvothermal method.The loading amount of Bi₂WO₆nanosheets on the surface of one-dimensional La₂Ti₂O₇nanofibers can be controlled by adjusting the addition amount of sodium tungstate and bismuth nitrate in the solvothermal process,and the effect of different loading amounts of Bi₂WO₆nanosheets on the performances of La₂Ti₂O₇/Bi₂WO₆heterojunction photocatalyst is investigated.Under simulated sunlight irradiation,the photodegradation rates of TCH and MB are 87.48%and90.41%in 20 min and 50 min,respectively,and the photocatalyst still maintains superior photocatalytic activity after three cycles.3.La₂Ti₂O₇/g-C₃N₄binary one-dimensional nanostructure heterojunction photocatalyst is successfully prepared by the combination of electrospinning with gas-solid fumigation.Under simulated sunlight illumination,the photodegradation rates of TCH and MB reach94.54%（50 min）and 91.14%（40 min）,respectively,demonstrating excellent bi-functionality of degrading antibiotic and organic dye.4.By using the combination of electrospinning with solvothermal method,BiOBr nanosheets are successfully loaded on La₂Ti₂O₇nanofibers to form La₂Ti₂O₇/BiOBr p-n heterojunction photocatalyst.The photocatalyst exhibits superior bi-function of degrading organic dye and antibiotic under simulated sunlight irradiation,and the photodegradation rates of TCH and MB are respectively 98.21%（20 min）and 98.25%（25 min）.The four kinds of heterojunction photocatalysts constructed based on electrospinning technology have excellent photocatalytic activity,and the proposed designing philosophy and preparation method provide new idea for developing La₂Ti₂O₇based photocatalysts.