Preparation Of Modified TiO₂ Nanofilms And Study On Their Photocatalytic Performance

With the rapid development of modern industry,the energy shortage and environmental degradation problems had already attracted extensive attention.Photocatalytic technology could not only effectively use the solar energy to degrade the harmful substances of environment,but also transform the low density of the solar energy into high density storable chemical energy.TiO₂ photocatalyst had been the focus of the photocatalytic technology research by its advantages of non-toxic,low-cost,stable property.However,the large energy gap and the fast recombination of photogenerated carriers limited its practical application.This paper mainly improved the photocatalytic activity of TiO₂ through the morphology control,precious metal loading and semiconductor composite.Detailed research were as follows:?1?One-step hydrothermal method was used to prepare TiO₂ nanostructured films.Concentration of the initial reactant was adjusted to receive nano flake,linear,ball,grass and corn shape five different morphology of TiO₂ nanometer thin film structure.Through the UV-Vis absorption characterization,the grass and corn shape TiO₂ nano-films were selected as precursors for noble metal loading and semiconductor composite reaction.?2?The ethylene glycol adjuvant hydrothermal was used to prepare the TiO₂ nanometer grass film and the microwave assisted reduction method was used to prepare the Au/TiO₂ composite material.Through characterization results,the Au nanoparticles?Au NPs?could be uniformly disperse on the surface of the of TiO₂ nanometer grass film.And,Au/TiO₂ composites had Au characteristic absorption peak in 500-600 nm range,the local surface plasma effect of Au NPs?LSPR?markedly enhanced the Au/TiO₂ light absorption in the visible range.Au particles could reduce the intensity of PL spectrum and improve the photocurrent density of TiO₂.The recombination of photogenerated carriers also was effectively restrain through the addition of Au NPs and the degradation efficiency of MB under the ultraviolet-visible and visible light irradiation increased more five times than pure TiO₂.The degradation rate of 16.0 cm² 2.0Au/TiO₂ to 50 mL 5 mg/L of MB could reach 97.41%within 90 min.?3?The corn-shaped TiO₂ nano-film was prepared by glycerol-assisted hydrothermal method,which was used as the precursor of the reaction.The in-situ microwave heating technique was used to prepared g-C₃N₄/TiO₂ by the combination of the high temperature thermal polymerization of melamine and the high temperature crystallization of TiO₂ in the air atmosphere.The research showed that the microwave heating technology was a simple and effective method to obtain g-C₃N₄ by thermal polymerization of melamine,which could realize in-situ construction of high-stability g-C₃N₄/TiO₂ heterojunction thin films.The prepared TiO₂ films with cracks and holes had visible light scattering ability,and the scattered light overlaps with the intrinsic absorption of g-C₃N₄ resulted in an absorption platform in the range of 400-550 nm.In addition,a magnetically driven rotating frame had been developed to enhance mass transfer during photocatalytic decomposition.The results showed that g-C₃N₄/TiO₂ films exhibited excellent activity under simulated solar irradiation.In addition to the enhanced mass transfer,visible light absorption,stable contact and effective charge transfer between g-C₃N₄ and TiO₂ could promote hydrogen production and light utilization efficiency.The hydrogen production rate of using 0.5 g melamine and 16.0 cm² TiO₂ can reach 13.8 mmol h^-1m^-2compared to the g-C₃N₄/TiO₂ membrane.