Fabrication Of TiO₂-graphene Nanocomposite Deposited Ag Nanoparticles:Application In Photocatalysis And Antibacterial

As a representative material in the field of photocatalysis,titanium dioxide had been a research object for researchers.In recent years,scientists had become more likely to research the High-energy crystal face and its three-dimensional structure.In particular,since 2008,a report pointed out in the NATURE that the density functional theory shows that the F atom can control the surface free energy of the?001?crystal face,so that scientists had fabricated the TiO₂ with the percentages of?001?facets to be 47%.The researchers had studied the high-energy?001?crystal face more thoroughly and thoroughly.Based on the limitations of titanium dioxide photocatalysis,and the key factors of modification and the breakthrough of new materials and new theories,the photocatalytic performance of titanium dioxide was improved from three aspects.First,We had fabricated hollow microspheres TiO₂ with exposed high energy facets using Ti?SO₄?₂ as the titanium source and NH4HF2 as the fluorine source by hydrothermal method.The sample was prepared with the nominal molar ratios of fluorine to titanium for 2 that showed hollow microsphere structure with highly energetic?001?facets exposed.The photocatalytic activity of TiO₂ hollow microspheres prepared by different hydrothermal reaction temperature and reaction time was evaluated by using 10 mg/L Rhodamine B solution as simulated contaminants.The results showed that the microspheres had the best photocatalytic activity prepared with the reaction temperature of 200? and the reaction time of 12 h.The solution of 10mg/L Rhodamine B was completely degraded and the degradation rate reached 96% at fifty minutes.Second,Graphene oxide was prepared by the modified Hummers oxidation method,concentrated sulfuric acid,concentrated phosphoric acid and KMnO₄ as intercalation oxidants,flake graphite as raw materials.The oxygen-containing groups on the surface of graphene oxide were removed by hydrothermal reduction method to obtain graphene.The effects of oxidation time on the morphology and adsorption properties of graphene were investigated.The results showed that the adsorption time of Rhodamine B was better as the oxidation time was 24 h.The adsorption process was in accordance with the pseudo-second order kinetic model.The linear correlation coefficient R22 of pseudo-second order kinetics was 0.99995 and the adsorption capacity was 210mg/g.TiO₂/RGO composites were prepared by one-step hydrothermal method and two-step hydrothermal method.The hydrothermal reaction was carried out according to the optimum preparation conditions that the hydrothermal temperature was 200? and reaction time was 12 h.Different proportions of graphene composites were preparated by changing the amount of graphene oxide.The results showed that the photocatalytic degradation efficiency of OTGC-9 samples prepared by one-step hydrothermal method was higher than that of pure titanium dioxide,and the photocatalytic efficiency of OTGC-9 samples was about 3.4 times higher than that of pure titanium dioxide.The photocatalytic degradation efficiency of TTGC-6 sample prepared by two-step hydrothermal method was higher than that of pure titanium dioxide,and the photocatalytic efficiency of TTGC-6 sample was about 3.3 times higher than that of pure titanium dioxide.Thirdly,Ag/TiO₂/RGO composites with 1%,2%,3%,4% and 5% silver of the mass fraction were prepared by depositing nano silver on the surface of TiO₂/RGO composites under UV irradiation.The prepared samples were characterized by Scanning Electron Microscope?SEM?,Transmission Electron Microscopy?TEM?,X-ray Diffraction?XRD?,Energy Dispersive Spectroscopy?EDS?to analyze crystal structure and microstructure.The results showed that the nanometer silver was successfully deposited on the surface of TiO₂/RGO composites and the deposition of nano-silver on the surface of TiO₂/RGO composites could improve the photocatalytic performance of the samples effectively.The Ag-TiO₂/RGO composites had better photocatalytic performance and the degradation rate of Ag-modified TiO₂/RGO to 50mg/L Rhodamine B had achieved 95% at sixty minutes when the mass fraction of silver was 3%.With the increase of silver content,the bactericidal performance of the samples was improved gradually,and the bactericidal performance of Ag/TiO₂ was improved greatly.When the mass fraction of silver was 3%,the diameter of the inhibition zone was 7mm.When the mass fraction of silver was achieve to 5%,the diameter of the inhibition zone reached 8.5mm.