Preparation And Photocatalytic Performance Research Of Co-doped And Ni-doped TiO₂ Nanomaterials

In recent years, with the rapid development of industry and the rise of emerging industries, environmental issues and energy crisis have become increasingly serious, which bring a great hidden danger to social stability. Therefore, it is an inevitable trend of sustainable development to seek new materials of low cost, high safety, green environmental protection and high efficiency. At room temperature, organic pollutants can be degraded by TiO₂ nanomaterials under the sunlight, and converted into non-polluting substances through a series of chemical reactions. So TiO₂ shows good application prospects in the fields of water purification, air purification, self- cleaning and so on. Although TiO₂ has many advantages in photocatalytic technology, it also has some shortcomings, such as wide band gap, low utilization of natural light and high absorption of light threshold. In view of the above issues, by adjusting the preparation technology and doping modification, the photocatalytic activity of TiO₂ were improved.The pure TiO₂ nanomaterials were prepared by co-precipitation method combined with hydrothermal calcination method. The effects of hydrothermal reaction time and hydrothermal reaction temperature, calcination time and calcination temperature on the photocatalytic activity of pure TiO₂ were studied by single factor experiments. The optimum parameters were selected by orthogonal test. In addition, the effects of pure TiO₂ on the degradation rate of methylene blue in hydrothermal reaction was studied. The experimental results show the better experimental conditions: when the hydrothermal reaction time is 12 h, the hydrothermal reaction temperature is 150℃, the calcination time is 4h, the calcination temperature is 500℃, and the sodium hydroxide concentration is 10mol/L, the photocatalytic activity of the sample is the highest, and the degradation rate of methylene blue is 90.39%.Based on the optimum parameters, Co-TiO₂, N i-TiO₂ and Co/N i- TiO₂ were synthetised by the same method. The effects of different doping amount of metal ions on the degradation rate of methylene blue was discussed by means of photocatalytic experiments. We use XRD, SEM, TEM and EDS to characterize the polymorph, microstructure and elements of samples. Under the action of Co-TiO₂, N i-TiO₂ and Co/N i-TiO₂, the degradation rate of methylene blue are respectively 95.05%, 98.72% and 96.81%, which are respectively 4.66%, 8.33% and 6.42% higher than the degradation rate of methylene blue under the action of pure TiO₂. The results of XRD show that the Co-TiO₂, Ni- TiO₂ and Co/N i-TiO₂ are all anatase phase, the diffraction peak of（101） crystal face is sharp, and the samples have good crystallinity. The size of most samples is 15nm-25 nm, which can be seen from SEM and TEM, and the morphology is flaky structure. EDS analysis shows that Co ions and N i ions are successfully incorporated into the lattice of TiO₂.