Study On The Preparation And Properties Of Conjugated Polymer Composite TiO₂ Photocatalyst

TiO₂ with high photocatalytic activity, corrosion resistance, good stability, environment-friendly, relatively inexpensive, and the advantages of non-toxic to human body, was the most in-depth study of a photocatalyst material in the field of photocatalytic degradation of organic matter. But the band gap energy of TiO₂ is 3.2eV and only absorb UV, so utilization ratio of sun light is low, can not degradate organic pollutants in a very short period, and photo-electrons and holes are also easily combined.Ï€electron of conjugated polymers have higher level delocalization, a relatively small band gap, absorption can cover from ultraviolet to infrared spectral range, After the inorganic semiconductor and conjugated polymer composite, Inorganic particles performance as electronic grants, under natural light irradiation, electrons transfer from the conjugated polymers to the conduction band of inorganic nanoparticles, and the electrons of inorganic nanoparticles transfer to the conjugated polymers, this reduces the combination probability of photo-electrons and holes. conjugated polymers have good chemical stability, wider absorption range than TiO₂, high absorption coefficient, photo-electrons and holes easily transfer, oxidation-resistant ability, higher molecular weight can be controlled, the energy gap of conjugated polymer can be controlled which is closed to that of TiO₂, the presence of conjugated polymers broadens the spectral response range, thus greatly the utilization ratio of sun light increases, after heat treatment, getting a large surface area which can play a synergistic effect of photocatalytic. In this paper, conjugated polymer was used to modify the surface of TiO₂ which has the close energy gap, its dynamic behavior and photocatalytic properties was studied primarily, to reveale the interaction nature between conjugated polymer and TiO₂.TiO₂ powder, PFQ/TiO₂ and PFAlQ₃/TiO₂ photocatalysts were synthesized by sol-gel method and PPy/TiO₂ and PT/TiO₂ photocatalysts were synthesized by situ polymerization. The simples were characterized by a series of technologies including X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy(DRS), scanning electron microscopy (SEM), thermogravimetric differential thermal analysis(TG-DTA) and Energy dispersive X-ray spectroscopy (EDS). And the kinetics of degradating methyl orange solution was studied primarily.PFQ/TiO₂ and PFAlQ₃/TiO₂ photocatalysts was synthesized by sol-gel method, Investigated the heat treatment temperature on the phase structure, optical properties and microstructure of TiO₂. The results showed that PFQ/TiO₂ and PFAlQ₃/TiO₂ photocatalysts was mainly composed of anatase phase but anatase undergoed some distortion and With the heat treatment temperature,anatase tranformed to rutile, and polymer gradually reduced, and block structure changed to granular structure, After composite, the visible photocatalytic activity was enhanced, When the heat treatment temperature is 480℃, the band gap energy of PFQ/TiO₂ and PFAlQ₃/TiO₂ photocatalysts was 2.99eV and 3.03eV, and the absorption edge red shifted to 415nm and 410nm respectively, Conjugated polymer composited with TiO₂ produced a synergistic effect, accelerated the photocatalytic degradation efficiency, the visible photocatalytic activity of PFQ/TiO₂ and PFAlQ₃/TiO₂ is 93.53% and 98.00% respectively after 2h visible light irradiation, but the visible photocatalytic activity of TiO₂ is 2.5%, the visible light photocatalytic activity is improved significantly. PPy/TiO₂ and PT/TiO₂ photocatalysts were synthesized by situ polymerization.PPy/TiO₂ photocatalysts was mainly composed of anatase phase and particle size is nano-size, UV-visible spectrum extended to the visible area and the band gap energy decreases by the 3.19eV to 2.87eV, and the absorption edge red shifted from 389nm to 433nm; After composite, the particles have better dispersion, the visible photocatalytic of PPy(1:120)/TiO₂ is highest, is 73.5% after 5h visible light irradiation, which is was 2 times higher than that of pure TiO₂; PT/TiO₂ photocatalysts was also mainly composed of anatase phase and particle size is nano-size, have a new absorption band from 400nm to 600nm, maximum absorption wavelength is about 520nm, and have the strong adsorption capacity, with the thiophene content increased, the adsorption capacity increased, which is helpful to photocatalytic activity, the visible photocatalytic of PT(0.75:100)/TiO₂ is highest, is 73.5% after 6h visible light irradiation, which is was 1.75 times higher than that of pure TiO₂.When the concentration of methyl orange solution is 10 mg·L-1, the photocatalytic degradation of methyl orange in aqueous solution was first-order reaction on the PPy/TiO₂ and PT/TiO₂ photocatalysts.