Improvement Of The Photocatalytic Performance And Photostability Of α-S Through Interface Modification

?-S(alphaphase sulfur)seems to be the ideal materials in photocatalyst due to the suitable band gap,good stability in water,earth-abundant and environmental benign properties.However,owing to the large particle size,poor hydrophilcity and fast recombination of photoinduced e~--h~+pairs,the reported pure?-sulfur exhibited relatively low visiblelight photocatalytic activity.Graphene,a new two-dimensional and carbon-based nanoscale material,possesses excellent mobility of charge carriers,large specific surface area,good chemical and mechanical stability,thus showing to be a good candidate to modify other semiconductors.In addition,P25 is another kind of widely applied material in photocatalysis for the strong oxidizing power,high chemical inertness,and long-term stability.The improvement of photocatalytic of?-S could be achieved via the decoration of graphene and P25.This thesis focuses on the following three aspects.Firstly,in this thesis,graphene oxide(GO)was synthesized via modified Hummers method using graphite as starting material.Sulfur–graphene(SG)composites were prepared by one step and in-situ method.This in-situ method could not only control the growth of S particles but also reduce GO to rGO at the same time.By varying the ratio of GO to demonstrate the influence that resulted to the adsorption capacity and photocatalytic performance.The experiment results confirmed that the higher content of graphene,the better adsorption capability of SG composites.However,the photostability is poor according to the recycle experiment.On the basis of our pioneer work,a novel core-shell S@rGO composite was designed by the assistance of CTAB(cetyltriethylammnonium bromide).In this process,CTAB not only tailors the growth of?-S with small particle size,but also renders?-S with positive charges.The rGO nanocoating enhanced the absorption of visible light,facilitated the separation of photogenerated charges,promoted the adsorption of dye moleculars,and provided the perfectchemical protection to inner sulfur particles.As a result,the rGO nanocoating improved the photocatalytic activity and photostability of the sulfur photocatalyst at the same.The enhanced photocatalytic performance of SG hybrid can be attributed to the following four aspects:(1)the better adsorption capability of SG composites;(2)the increasing hydrophilcity;(3)expanded response wavelength;(4)and improved charge carrier separation efficiency.For the purpose of accelerating the commercial process of photocatalyst,commercial S and P25 were chosen as raw material to prepare sulfur/P25heterostructure via a facile grinding combined melt-diffusion method.The heterojuncations could be formed due to their suitable band gap locations,which lead to the efficiency separation of charge carriers.And drastic quenching of photoluminescence intensity of P25 is observed after the formation of sulfur/P25heterostructures,implying that the photogenerated electrons and holes have better separation efficiency in the PSx heterostructures.The photocatalytic results exhibited that sulfur/P25 heterostructures obtain exelent photocatalytic activity and well photostability.