Study On The Preparation And Photocatalytic Degradation Of Vanadium Oxide Composite Microspheres Towards Gaseous Benzene

Volatile organic compounds?VOCs?are the most harmful pollutants in the air.Among various VOCs,benzene is one of the recalcitrant aromatic hydrocarbons in the polluted urban atmosphere.For the VOCs removal,the photocatalytic process is proved to be a promising technology.For the photocatalysts,titanium dioxide?TiO₂?is one of the most basic materials in our daily life,which shows a great potential application.However,the practical applications of TiO₂ are still limited by their fast electron-hole recombination and wide band gap energy?3.2 eV?,as they only absorb a small portion of the solar spectrum in the UV light region.In order to improve the photocatalytic properties of TiO₂,V₂O₅@TiO₂ and TiO₂@V₂O₅ microspheres are successfully synthesized in the present work.The samples are characterized by XRD,FESEM,TEM,XPS and UV-Vis.By choosing the photo-degradation of gaseous benzene as reference material,the potential photocatalytic properties of V₂O₅@TiO₂and TiO₂@V₂O₅ core-shell microspheres are investigated,respectively.The experimental results show that the two kinds of vanadium-titanium composits have good photocatalytic performance.The improvement of photocatalytic activity is attributed to the fact that the well-contacted surface betweeb TiO2 and V2O5 will form a heterostructure,which could the effective separation of the photoinduced charge carriers to a great extent.Moreover,TiO₂-V₂O₅ composite can broaden the light absorption range and enhance the light absorption intensity.Besides,the large specific surface area of the microsphere structure,which is favorable for the contact between the active species and the gas benzene.The main experimental contents and photocatalytic effects are as following:1.In order to enhance the light absorption properties,we designed V₂O₅@TiO₂core-shell composite microspheres:V₂O₅ microspheres were successfully synthesized by a hydrothermal method in the present work.The effects of the hydrothermal temperature and hydrothermal time on the morphology of V2O5 microspheres were studied,and the growth mechanism of V₂O₅ microspheres was analyzed.V₂O₅@TiO₂core-shell microspheres were prepared by adding different TBOT amounts,the diameter of V₂O₅@TiO₂ core-shell microspheres is increased if compared to that of the V₂O₅ microspheres,and the surface becomes rough.V₂O₅@TiO₂ core-shell microspheres possess an obvious enhancement for light absorption ability in the range of UV and visible light compared with that of V2O5 powder.The photocatalytic degradation of gas benzene showed that V₂O₅@TiO₂-20%microspheres possess the best photocatalytic activity under UV-visible light irradiation,i.e.,about 91.7%of converted-benzene is completely mineralized to CO₂ and H₂O in 65 min.2.In order to broaden the light absorption range,we designed TiO₂@V₂O₅core-shell composite microspheres:TiO₂ hollow microspheres were successfully synthesized by a template method in the present work,and the influencing factors for the formation of TiO₂ hollow microspheres were carried out and the best ratio was found.TiO₂@V₂O₅ core-shell hollow porous microspheres are successfully synthesized through a facile hydrothermal progress followed by a sol-gel technique,the diameter of TiO₂@V₂O₅ microspheres have no change compared to that of TiO₂hollow microspheres.UV-vis spectra are used to character the optical absorption,it shows that TiO₂@V₂O₅ core-shell microspheres possess an obvious enhancement and the absorption edges of TiO₂@V₂O₅ microspheres will shift to the visible light range compared with that of TiO₂ hollow microspheres.The photocatalytic degradation of gas benzene showed that TiO₂@V₂O₅-10%core-shell hollow porous microspheres possess the best photocatalytic activity of 100%in 55 min under UV-visible light irradiation,about 91.7%of the converted-benzene is completely mineralized to CO₂and H₂O.