Effect Of Calcination Temperature On The Visible-light Response Of Modified TiO₂ Nanopowders

City environmental issue is increasingly more serious with the development of industrialization, in this context, photocatalysis technology using TiO2 for organic degradation provides a solution to remove the pollution. Though low quantum efficiency as well as the large band gap confine the practical application of TiO2, N doping has been proved to be effective in extending the spectral absorption of TiO 2 from ultraviolet region to visible region. Even so, N doped TiO2 prepared with different methods show great difference in photocatalytic activity, the visible- light response mechanism is also in dispute. In order to promote the commercial application of TiO2, doping process for high visible- light performance has been developed by regulating the annealing temperature in this paper. In addition, the effect of calcination temperature on the visible- light response of N, H- codoped TiO2 has also been deeply studied in comparison. During the research the variation of crystal structure, surface topography, optical property as well as the visible-light photocatalytic performance along with the elevation of temperature has resulted as follows:1. Along with the increase of annealing temperature, doping density of N-doped samples rises up rapidly, doping sites gradually transit from institution to the substitution, and correspondingly the visible- light absorption is also remarkably strengthened. The side effect may be the increasing amount of defects, such as oxygen vacancies, and more likely acting as the recombination site of photo-generated carries which inhibit the photocatalytic ability of TiO2 under visible-light irradiation.2. N, H-codoping method would alleviate the speed of N doping and maintain the phase stability when the heating temperature is increased comparing with solely N doping method, amorphous layer may also grows on the surface of N,H-codoped samples. The effect of temperature applied to the visible- light absorption would also be mitigated, while the separation rate of electrons and holes is promoted and give rise to better visible- light photocatalytic performance.3. Excessive heat in N-doping process would bring in the formation of TiN, which greatly enhance the absorption ability of samples but function as the recombination center of carriers and poison the photochemical reaction. In conclusion, to guarantee the excellent property of TiO2, the temperature of heat treatment should be controlled below 600? when N doping or N, H-codoping technology applied to industrial production.