The Preparation And Performance Of Visible Light Responsive Nano-tio₂ Hollow Sphere Photocatalyst

Titanium dioxide?TiO₂?has become a hot spot in the field of catalysis because of its low cost,good stability and high catalytic activity.However,the application of TiO₂photocatalyst is restricted by the wide band gap and low utilization rate of solar light.In order to improve the visible light responsiveness of nano-TiO₂ photocatalyst,the following researches were carried out in this paper:The monodisperse TiO₂ microspheres?TMS?were sythesized by liquid phase method using tetrabutyl titanate as titanium source.TiO₂ hollow spheres?THS?were sythesized by etching reaction of TMS under hydrothermal condition,drying and calcining treatment.The effects of etching time and calcined temperature on the morphology,structure and photocatalytic properties of THS were investigated.The results showed that the THS sythesized by TMS etched for 4h exhibited the best photocatalytic activity after calcining at 300^oC for 2h.The degradation rate of THS for rhodamine b?RhB?aqueous solution after 90 min reached 73.6%under visible light irradiation,and the degradation reaction rate constant?k?was about 2.7 times than that of TMS.The anatase phase nitrogen doped TiO₂ hollow spheres?N-THS?were sythesized by impregnating,drying and calcining treatment when ammonium nitrate?NH₄NO₃?was used as nitrogen source.The effects of NH₄NO₃ concentration and heat treatment temperature on morphology,structure,light response ability and photocatalytic properties of THS were investigated.The N-THS obtained by calcined at 200^oC for 2h exhibited good photocatalytic activity when the concentration of NH₄NO₃ is 2mol/L.The degradation rate of RhB aqueous solution after 90min reached 90.9%under visible light irradiation,and k is about 4.5 times than that of TMS.The Ag nanoparticles diameter ranged in 2⁴nm were synthesized by insitu reduction method using silver nitrate as Ag source and sodium borohydride as deoxidizer.Ag loaded N-THS?N-THS@Ag?can be obtained after Ag loading,impregnating,drying and calcining treatment.The anatase phase N-THS@Ag with good photocatalytic activity can be obtained by calcined at 200^oC for 2h when the loading of Ag is 2%.The degradation rate of RhB aqueous solution after 60min and 90min reached91.7%and 93.6%respectively under visible light irradiation,and k is about 6.4 times than that of TMS.