Urea Modified Industrial TiO ₂ Preparation And Catalytic Properties Of Visible Light

In recent years,much attention has been paid for heterogeneousphotocatalysis owing to its potential application in many areas,especiallythe treatment of environmental pollutats. TiO₂is the extensive attention athome and abroad,beause it is stable,cost effectiveandnon-corrosive.How-ever,TiO₂as photocatalyst has some disadvantage,the photocatalyticactivity of TiO₂is limited by fast charge-carrier recombination and its lowquanta efficiency, the pure TiO₂absorbs only the small ultravioletpart（3-5%） of solar light due to its wide band-gap of3.2ev.The lower quantaefficiency and wide bandgap are the main factors to restrict the practicalityand industrialization of photocatalytic oxidation.Therefore, reducing therecombination of electron-cavity pairs, any improvement of photocatalyticefficiency and utilization of visible light will have a profound effect.In our study, the industry TiO₂was used as the precursor and the ureawas used as the nitrogen source, different mass ratios of them were put intothe meffle furnace and calcined, then we got N-TiO₂, a new complexphotocatalyst. The structure shape and spectrum characteristic werecharacterized by FT-IR, XPS, XRD, TEM, TG-DSC, FS and UV-Vis. Thephotocatalytic activities under visible light were evaluated by degradationof methylene blue. Calcined temperature, calcined time and mass ratios ofurea and industry TiO₂were the three influence factors. We investigate themechanism about the new N-TiO₂photocatalyst which was modified by area.The results show that:（1）The photocatalytic activity of3N-TiO₂-450was the best of all thesamples. It was obtained under temperature450℃, calcined1h and the massratios of urea and titanium dioxide was3:1. The degradation of5mg/L MBreached95.1%under the visible light irradiated4h. In the gas experiment,the degradation of toluene was28.26%after100min irradiation. Theparticle size of3N （18.1nm）was bigger than pure titanium（17.0nm）.（2）We find that the polymeric graphite-like carbon nitride（g-C₃N₄）which obtained from area under high temperature homogeneous distributedon the TiO₂surface from FT-IR, XPS and XRD analysis. TG-DSCspectrogram indicated that g-C₃N₄can be produced under the temperature higher than330℃and resolved under the temperature higher than370℃.UV-Vis results show that the absorption sideband of C₃N₄-TiO₂hasred-shift and widen the spectrum absorption range. Its π-π*electronictransition were induced by visible light, making the photocatalytic activityof TiO₂under visible light improved greatly. were great improved.