Ammonia Modified Titania Preparation And Visible Light Photocatalytic Properties

Represented by TiO₂semiconductor photocatalyst to deal withenvironmental pollutants have received extensive attention of the world,and shown a good prospect.The titanium dioxide photocatalyst have a goodchemical stability, non-toxic, highly efficient, low cost, however due to theTiO₂band gap was wider （anatase phase3.2eV）,Corresponding to anexcitation wavelength at385nm, To show that the photocatalytic activity,Only under the excitation of ultraviolet light,The content of the ultravioletlight in sunlight accounted for only3%⁵%,therefor,modification forTiO₂and improve the photocatalyst catalytic performance has a greatresearch significance.In this paper， using the industrial titanium dioxide as raw material,prepared by heat treatment of N-doped photocatalyst under differentammonia concentration, using X-ray photoelectron spectroscopy （XPS）,X-ray diffraction （XRD）, transmission electron microscopy （TEM）, Fouriertransform infrared spectroscopy （FT-IR）, Photoluminescence （PL） and UVvisible diffuse reflectance spectroscopy （UV-vis DRS） to characterize thecacatalysts. through liquid phase and vapor phase activity degradationexperiments, Liquid phase experiment of methylene blue for targetpollutants, gas phase experiment NO target pollutants, We evaluated thephotocatalytic activity of the catalyst under different calcinationtemperature, different calcination time and different ammonia concentration,explored the industrial TiO₂doped with ammonia as a nitrogen sourcemodified visible light photocatalytic activity mechanism. The results showthat:Industrial TiO₂had the best liquid-phase degradation of methylene bluevisible light activity in the calcination temperature of500℃, calcinationtime of3h, the ammonia concentration of99%,On the concentration of5mg/L methylene blue degradation rate of93%;In the Vapor phase activityexperiments, after100minutes of photocatalytic degradation, calcinationtemperature in400℃, calcination timeat3h, ammonia concentration was99%, light degradation catalysts for gas phase concentration for500PPB NO visible light activity was best， NO degradation rate to be38%in themeteorological activities experiment.By X-ray diffraction （XRD）, specific surface area （BET）, pore sizedistribution, transmission electron microscope （TEM） characterizationanalysis, the light under different calcining temperature of the catalyst aremainly distributed in between2⁸nm， N doping photocatalyst had thecharacteristics of mesoporous structure, modification after doping TiO₂grain size relative to the industrial pure TiO₂（17.2nm） had a certainincrease, and with the increase of calcination temperature, the modifiedTiO₂grain size would be increase.By ultraviolet-visible diffuse reflectionspectrum（UV-vis DRS）analysis,with the increase of calcination temperature,catalyst visible light absorption band occurred red shift, along with the riseof calcining temperature and forbidden band width is reduced. With theincrease of calcining time and the increase of ammonia concentration,enhance light absorption intensity, so the photocatalytic activity will behigher. By fluorescence spectroscopy （PL） and X-ray photoelectronspectroscopy （XPS） analysis shows that when calcining temperature was500℃, calcination time was3h and ammonia concentration was99%, thefluorescence intensity was lowest， and more conducive to inhibit electron-hole composite.N-doped photocatalyst is substituted type doping. N dopingquantity increased with the increase of calcination temperature.