The Preparation Of Ammonium Chloride Modified Titanium Dioxide And Photocatalytic Performance Study

Titanium dioxide is considered the most promising application as photoeatalystamong many semiconductor photocatalysis materials because of its strong oxidationability, chemical stability, low cost and non-secondary pollution. However, TiO₂photocatalytic oxidation technique is limited by its wide band gap, which requiresultraviolet irradiation for photocatalytic activation. If the photocatalytically activeregion is expanded to the visible light region, sunlight sources can be used moreefficiently.In this paper, by using Ti（OC4H9）4as precursors and ammonium chloride as dopingsource, N-Cl-C-tri-doped TiO₂photocatalysts were prepared. The as-prepared TiO₂powders were characterized with scanning electron microscopy （SEM）, transmissionelectron microscopy （TEM）, X-ray diffraction （XRD）, X-ray photoelectronspectroscopy （XPS） and UV-Vis diffuse reflectance spectroscopy （DRS）. In addition,the mechanisms of the enhancement of visible-light photocatalytic activity ofN-Cl-C-tri-doped TiO₂photocatalysts were analyzed in detailed. The effects ofpreparation method、types of hydrolysis inhibitor、ammonium chloride content andcalcination temperature on visible-light photocatalytic activity were studied. The effectsof concentration of RhB, catalyst dosage and irradiation wavelength on performance forthe degradation of rhodamine B were also investigated.The results showed:1、The structure, visible light absorption and the degradation of phenol of thetri-doped TiO₂with different preparation methods are investigated, it found thatN-Cl-C-tri-doped TiO₂prepared by the sol-gel method demonstrated higherphotocatalytic activity due to the single anatase phase, smaller crystalline size, highervisible absorption ability and visible-light photocatalytic activity.2、The effects of different hydrolysis inhibitors on the photocatalytic activity ofthe tri-doped TiO₂were studied. SEM，TEM，XRD，XPS and DRS indicated thatas-prepared sample that was prepared bynitric acid was spherical particles, which hadsingle anatase phase and more hydroxyl radicals. Compared with that prepared byhydrochloric acid, N-Cl-C-tri-doped TiO₂prepared by nitric acid had lower visible light absorption, but higher photocatalytic activity.3、The photocatalytic of N-Cl-C-tri-doped TiO₂is significantly affected by theammonium chloride doping amount and calcination temperature. XPS analysis revealedthat N elements as the form of O-Ti-N and NOx existed into the lattice and on thesurface of TiO₂, respectively. One part of Cl elements incorporated in TiO₂via theO-Ti-Cl linkages, which was possibly formed by the substitution of the oxygen in TiO₂lattice. And a small amount of Cl elements existed on the surface or in the interstice ofTiO₂photocatalyst in the form of Cl-. C elements modified on the TiO₂as the form ofCO₃^2-. The optimum doping amount and calcination temperature were3.0mol%and250℃, respectively. Under the visible-light （420-800nm） irradiation with120min, theremoval rate for RhB and phenol could achieve95.23%and80.13%, respectively.