Upconversion Photocatalytic Property Of Er³⁺-Yb³⁺ And Er³⁺-N TiO₂ Nanocrystal Under Visible Light

TiO₂ as photocatalyst is widely used to photodegradate many pollutants for its relatively high catalytic reactivity, physical and chemical stability, avirulence and cheapness and so on. However, there are many problems in TiO₂-based photocatalysis such as low quantum efficiency and little utilization of solar energy and so on. Besides, the photocatalytic degradation method treating pollutants needs equipments and large numbers of energies as light source, so it prevented to using TiO₂ photocatalyst effectively. In this paper, as a matrix, titanium dioxide could degrade organic compounds under visible light not only by doping rare earth ions and non-metallic elements but also by using rare earth ion upconversion luminescence properties. Specific tasks are as follows:1. Er³⁺-Yb³⁺ co-doped TiO₂ samples were prepared by the sol-gel and impregnation method. Er³⁺-N co-doped TiO₂ new photocatalyst samples were prepared by the hydrolysis-precipitation method.2. Er³⁺-Yb³⁺ co-doped TiO₂ and Er³⁺-N co-doped TiO₂ photocatalysts were characterized by XRD,BET,TEM,SEM,AFM,UV-Vis and Upconversion Photoluminescence.3. The effect of photocatalytic degradation for methyl violet by using Er³⁺-Yb³⁺ co-doped TiO₂ nano-crystals was discussed. The process of photocatalytic degradation on different calcination temperature (900°С, 950°С, 1000°Сand 1050°С), the initial solution concentration, amount of catalyst and pH were investigated. Moreover, the process of photocatalytic mechanism including conversion photoluminescence, energy transfer and dye photosensitive were discussed.4. The effect of photocatalytic degradation for methyl violet and phenol by using Er³⁺-Yb³⁺ co-doped TiO₂ nano-crystals was discussed. The influence of different calcination temperature (400°С, 500°С, 700°Сand 900°С), the amount of N doped on the photocatalytic degradation effect was investigated also. The degradation kinetics of the process was analysis and the effect of catalyst reuse was investigated.In a word, it indicated that the doped upconversion photocatalysis prepared could effectively degrade organic compounds under visible light. Degradation rate got up to 93.3% and 95.6% respectively. The degradation ratio of doped TiO₂ was obviously higher than the corresponding degradation ratio in the presence of undoped TiO₂ powder. Our work could expand the photo degradation application of nano-TiO₂ areas, particularly in the visible light irradiation of degrading organic compounds.