Controllable Synthesis And Photocatalytic Activity Research Of TiO₂ And Its Composites

In recent decades,considerable interests have been focused on nano titanium dioxide due to its novel physical and chemical properties and their high potential applications in many areas,such as catalysis,electrochemical and solar energy devices.The research focused on two aspects:Synthesis anatase single crystal and brookite Ti02 using TiCl3 as precursor,one-step hydrothermal synthesis nano-composites,depend on the reducibility of Ti3+ by means of oxidation-reduction using oxidative precursor;using titanium power and tetrabutyl titanate as precursor,HF as crystal surface control agent,Synthesis anatase TiO2 with high reactivity(001)plane.The growth mechanism and properties have been discussed.The main results are concluded as follows:(1)Using TiCl3 as precursor,successfully prepared nearly monodispersed rice-like anatase TiO2 with 20-30 nm in width,40-50 nm in length,without any surfactant.It can form hydrosol because of its prefect dispersability in water.The crystalline transition process and the morphology conversion were also investigated,which showed It undergone an amorphous to anatase during the transformation process.From the TEM of different reacting time,the Ostwald ripening process was showed.In order to form the most thermodynamically stable state,the crystal grows along the(001)plane,only the crystal top is(001),the most exposed plane is the(101),which is more stable,the above conclusion can be got from the HRTEM.High purity flower-like brookite titanium was synthesized through hydrothermal way,using NaOH as pH value regulator.By adjusting pH value,the morphology of the brookite can be controlled.The formation mechanism and photocatalytic performance were also studied.(2)Taking into account of the strong reduction of Ti(OH)3,and the oxidation capacity of noble metal ions,the redox reaction may be taken place at the interface of the two precursor,and then formed noble metal loading titanium dioxide.AgNO3 was tested firstly as precursor,The HRTEM analysis shows that Ag particles was loaded on the surface of Ti02,proved the feasibility of the experiment design.The Au and Pt loaded also carried out in the same way.Changing noble metal by graphite oxide(have oxidizing ability too),in the same way,we synthesiszed titanium dioxide-graphene complex successfully,and its catalytic efficience was higher than that of commercial photocatalyst P25,which can be got through the photocalitic degradation of methyl orange.The mechanism of the titanium dioxide-grapheme formation and the catalytic efficiency improvement were also put forward.(3)Anatase titanium dioxide with high activity was synthesized by using tetrabutyl titanate as precursor,HF as plane controlling agent,with length of 1.5 μm,thickness of 0.5 μm.The impact of butyl on the morphology was also investigated,the crystal using tetrabutyl titanate as precursor show more perfect morphology,this showed that butyl was benefit for the formation of(001)plane.(4)Flower-ball like titanium dioxide with high reactivity plane was synthesized by using titanium power as precursor.By controlling the amount of HF,the flower-ball like and spherical can be controllable synthesis.A reasonable speculate of the HF in the role of crystal growth was also put forward.(5)In order to reduce the particle size,increase the specific surface of the catalyst,improve the performance more effectively,a sol-gol assisted hydrothermal method was innovatively proposed.The catalyst with a side of 40 nm in length was synthesized,showing perfect photocatalytic efficiency.In the same condition,in 80 min,the degradation efficiency of the as-synthesized TiO2 can reach 97%,while the commercial p25 was only 85%.