Preparation Of Amorphous TiO₂ Nanoparticles And Study Of Its Photocatalysis

TiO₂ has the advantages of stable chemical properties,low cost and strong absorption ability of ultraviolet light,which has attracted wide attention in the field of photocatalysis.However,the crystalline TiO₂ cannot absorb visible light because of its large bandgap energy?3.2 eV?.Therefore,the disadvantage of low utilization of visible light is one of the problems that disturbed the development of TiO₂ photocatalysis technology.The structure of amorphous TiO₂ is different from the crystalline TiO₂ and has different electronic structure and optical properties.Therefore,amorphous TiO₂ is expected to be one of the ways to solve the low utilization of visible light.The present report usually prepared a high photocatalytic activity TiO₂ nanoparticles by some complex technology,such as doping modification,noble metal deposition,semiconductor compound.The study on photocatalytic activity of TiO₂ nanoparticles with high specific surface area by simple preparation method has been rarely reported.In this paper,a simple method of amorphous TiO₂nanoparticles was prepared with good photocatalytic performance both under the condition of the ultraviolet?UV?and the solar light.TiO₂ amorphous nanoparticles were prepared by direct precipitation method,with TiCl₄ as the source of Ti,with NH₃·H₂O as precipitant,studied the influence of different kinds of surfactant on the particle size,sphericity and reunite degree of TiO₂amorphous nanoparticles,then determine lysine as the most suitable surfactant in the preparation of TiO₂.And then adjust the lysine concentration,reaction temperature,reaction time and the solution pH,identify the optimal reaction parameters,and the parameters is used in the experiment of other precipitants,can also prepare TiO₂ amorphous nanoparticles with small particle size and better dispersion.In the end,we characterize the TiO₂ amorphous nanoparticles prepared as the above parameters and study their photocatalytic performance in ultraviolet and visible light conditions.The results show that use 3 mol/L NH₃·H₂O as precipitant,0.02 mol/L lysine as surfactant,reaction at room temperature for 1 h,after washing and calcination,amorphous TiO₂ nanoparticles with the size of 3.43 nm,6.37 nm and 3.57 nm can be prepared.XRD,TEM,FTIR,TG/DTA and SAED were used to characterize the particles.XRD analysis shows that the TiO₂ precursor after300?calcination remains amorphous structure;The TEM shows that the particles are of small size and good dispersibility.FTIR analysis shows that there are some organic impurities existed in the precursor,and after 300?calcination,pure TiO₂ particles are prepared.The photocatalytic performance of TiO₂ amorphous nanoparticles with different particle sizes was studied.The UV-vis shows that bandgap energy of the prepared amorphous TiO₂nanoparticles was 2.86 eV,3.15 eV,2.95 eV,respectively.According to the results of the catalytic degradation of Rhodamine B solution under ultraviolet light for 120 min,the degradation rate is93%,36%and 75%,respectively.The photocatalytic rate is 19.76×10^-3,3.41×10^-3,10.89×10^-3min^-1,respectively.Then studied the photocatalysis under the condition of solar light irradiation for 24 h,the experimental results show that the degradation rate of Rhodamine B solution was91%,43%and 88%,respectively.The photocatalytic rate is 4.88×10^-3,2.98×10^-3,3.53×10^-3 min^-1,respectively.