Preparation And Photocatalytic Properties Of Multiphase Mesoporous TiO₂ Composite Photocatalysts

Photocatalytic technology has received great attention in solving organic pollutants in wastewater.In order to improve the solar energy utilization and visible light catalytic degradation properties of TiO₂,in this paper,TiO₂ based photocatalytic materials has been developed.By optimizing the preparation conditions,multiple-phase mesoporous TiO₂ has been prepared.Non-metal elements N was doped into the triple-phase TiO₂ which was loaded over the surface of C ball.By doing this both the band gap of TiO₂ is narrowed and the active site density of TiO₂ is increased.The adsorption and photocatalytic degradation of organic pollutant ability has been improved greatly.The visible light catalytic effect of the sample was assessed and the visible light catalytic mechanism was proposed.?1?Three-phase mesoporous TiO₂ composite semiconductor materials:Preparation conditions,including different titanium sources,different calcination conditions and different calcination temperatures,for multiple-phase mesoporous TiO₂ has been optimized.Mixture of tetra-butyl titanium?TBT?and titanium tetrachloride?TiCl4?was used as titanium source,the hydrothermal-sol method for precursor preparation was applied and the samples were calcinated under air atmosphere.The samples were fully characterized.Rhodamine B?RhB?and malachite green were used as pollutant model for the assessment of visible light photocatalytic performance of the samples.The results showed that sample was three-phase mesoporous TiO₂ when calcinated under 300 ?and has the best photocatalytic performance.When illuminated under visible light for 40 minutes,it's absorption efficiency and visible light degradation efficiency is 9 times and 1.8 times that of non-mesoporous samples,respectively and is 68 times and 28 times that of P25,respectively.The capture of active species under visible light photocatalytic RhB demonstrates that superoxide radical?·O2-?and hole?h+?are mainly involved in the reaction.?2?Core-shell structure N doped TiO₂@C heterostructure compound semiconductor materials: By using C ball as core,tetra-butyl titanium and titanium tetrachloridetitaniumas sources,different quantity of urea as N source,core-shell structure N doped TiO₂@C was fabricated.By controlling the calcination temperature,the crystalline of TiO₂ was regulated.X-ray powder diffraction?XRD?demonstratesthat with the increase of calcination temperature,TiO₂ can be tuned from brookite/anatase to anatase/rutile and at last to rutile crystal phase.X-ray photoelectron spectrometer?XPS?demonstrates that N was doped into the lattice of TiO₂.Visible light photo-degradation of malachite green study showed that when using 1 g urea and calcined under 550 ?,the prepared sample N?1?-TiO₂@C-550 ? had the best catalytic efficiency of 75 %,which is 11 times that of P25 under the same condition.The capture of active species demonstrates that hydroxyl radicals?·OH?and superoxide radical?·O2-?are mainly involved in the reaction in which ·OH plays the most important role.