Controlled Synthesis Of Multi-morphological Nano-TiO₂ And Preparation And Characterization Of TiO₂-based Composite Photocatalyst

Titanium dioxide?TiO₂?is a semiconductor compound with excellent optical and photochemical properties.It is an important way to improve the quantization efficiency of nano TiO₂,expand the optical response of TiO₂ to the visible light range and improve its photocatalytic efficiency by adjusting the structure and morphology of TiO₂,combining nano TiO₂ with other semiconductors to form heterostructures and depositing noble metals on the surface.At present,there are some problems in this technical field,such as less kind of TiO₂ morphology,poor scale matching between the composite semiconductor and the lack of research on three-component heterojunction.In view of these problems,it is necessary to carry out controllable synthesis of multi-morphological nano TiO₂ and prepare TiO₂-based composite photocatalyst.In this paper titanium oxysulfate?TiOSO₄?is used as the source of titanium.By using alcohol-thermal method,three kinds of morphologies of nano TiO₂ were controllable prepared including hollow tubes.Also preparation in the similar particle size of nano TiO₂-CdS heterojunction,hollow tube TiO₂-CdS-Au and nanosheet TiO₂-ZnO-Au composite photocatalyst technology was studied.The as-prepared TiO₂ and its composite photocatalyst phase morphology,structure and photocatalytic degradation of pollutants,water decomposition hydrogen production and antibacterial performance were characterized and the compound of components and formation mechanism of the photocatalyst were studied.The influence on the synthesis of nano-TiO₂ with different morphologies and the properties of the products were studied.By changing the proportion?molar ratio?of TiOSO₄,ethanol and propylene triol in the reaction system and reaction time,the hollow tubular and round nano-sheet TiO₂ products can be obtained respectively.Without the addition of propylene triol,TiO₂ nanoparticles can be obtained.TiO₂ in each morphology was composed of anatase and rutile,and mainly anatase.Each TiO₂showed the performance of photocatalytic degradation of methyl orange under UV-light irradiation,among which the hollow tubular TiO₂ had the highest photocatalytic activity.The hollow tubular structure of TiO₂ has the characteristics of micropore-mesoporous,which is formed by the extrusion of a large number of nano-sheet materials.The inner diameter of the tube is about 500nm,the wall thickness is about200nm,and the thickness of nano-sheet is about 10nm.There are structural micropores in the nano-sheet.The structure and photocatalytic properties of CdS-TiO₂ heterostructure composite photocatalyst were studied.In CdS-TiO₂,CdS and TiO₂ have similar scales,and the primary particles are all at the nanometer scale?22nm and 12nm respectively?,which are uniformly combined through their interfaces.Under visible light irradiation?8h?,the degradation rate of tetracycline hydrochloride by CdS-TiO₂?50%of CdS?was 87.06%,and the catalytic effect of visible light was significantly stronger than that of pure TiO₂?synthesized TiO₂ and P25?and CdS.The preparation of ternary composite photocatalyst and its structure,properties and mechanism were studied by supporting CdS and Au nanoparticles on the surface of hollow tubular TiO₂.Among them,the photocatalytic activity of TiO₂-CdS/Au prepared in the order of first supporting CdS and then supporting Au was stronger than that of TiO₂-Au/CdS prepared in the order of first supporting Au and then supporting CdS.Hydrogen production of TiO₂-CdS/Au reached 14mmol/g after visible light irradiation for 4h.The mechanism for the improvement of the efficiency of TiO₂-CdS/Au is that Au is in the outermost layer of the core-shell structure,so its electron capture and surface plasmon resonance effect are effectively exerted,and thus the electron-hole separation efficiency of CdS is improved.TiO₂-Au/ZnO composite photocatalyst was prepared by supporting nano ZnO and nano Au on TiO2 nano-sheet.TiO2-Au/ZnO has good visible light catalytic performance and antibacterial ability,and the hydrogen production capacity under visible light irradiation for 4h is 1068?mol/g.The antibacterial effect of TiO₂-Au/ZnO coating film on Escherichia coli was 98.2%.