Each substance has a specific cell size and crystal structure, which has a corresponding relationship with diffraction intensity and diffraction angle. Therefore, the crystal structure can be identified from the diffraction data. In addition, according to the XRD diffraction pattern, Schercr formula is used: k K, (2), Lcos, where p is the radian value corresponding to the full width of the diffraction peak at half maximum; K is a morphological constant, which can be 0.94 or 0.89.
X-ray wavelength:1.4438+087a when copper target is used; L is the particle size or uniform diffraction domain size; E is the Bragg diffraction angle. The particle size of nanoparticles can be calculated by FWHM and the position (2a) of diffraction peak.
2. Thermal analysis and characterization. Thermal analysis technology is applied to the study of solid catalysts, mainly to track the weight change, thermal change and state change during the preparation of oxides.
The thermal analysis techniques used are differential scanning calorimetry and thermogravimetry, which are commonly used in oxide analysis, and are referred to as DSC-TG method for short. STA-449C comprehensive thermal analyzer (Germany, 10 National Naichi) was used for thermal analysis, and N2 protector was used. The heating rate is 65438 00℃/min.
3. Scanning tunneling microscope. Scanning tunneling microscope (STM) has high resolution at atomic scale, and the resolutions in the parallel and vertical directions are 0. 1 nm and 0.0 1nm, respectively, that is, it can distinguish a single atom, so it can directly observe the near-atomic image on the crystal surface. Secondly, a three-dimensional image of the surface can be obtained to measure the surface structure with or without periodicity.
The probe can manipulate and move a single molecule or atom, arrange molecules and atoms according to people's wishes, and realize nano-scale micromachining of the surface.
4. Transmission electron microscope. The size, morphology, particle size, distribution and particle size distribution range of particles can be observed by transmission electron microscope, and the particle size can be calculated by statistical average method. Generally, the electron microscope observes the particle size of the product particles, not the particle size. High resolution electron microscope (HRTEM) can directly observe the microcrystal structure, especially provides an effective means for the analysis of the interface substructure.
It can observe the solid appearance of tiny particles, and study the growth direction of crystals according to the crystal morphology, corresponding diffraction patterns and high-resolution images. The preparation of test samples is the same as that of SEM samples. In this study, JEM-30 10E high-resolution transmission electron microscope (Nissin) was used to analyze the crystal structure, and the accelerating voltage was 200 kV.
5.x-ray energy dispersive spectrometer method. Each element has its own characteristic X-ray, and qualitative and quantitative analysis results can be obtained according to the wavelength and intensity of the characteristic X-ray, which is the theoretical basis for component analysis with X-ray.
The element range of EDS analysis is Be4-U9a, the general measurement limit is 0.0 1%, the minimum analysis area is 5~50A, and the analysis time is only a few minutes. X-ray energy spectrometer is a micro-area analyzer.
Extended data:
There are many photocatalytic materials in the world, including oxide sulfide semiconductors such as titanium dioxide, zinc oxide, tin oxide, zirconium dioxide and cadmium sulfide. Among them, titanium dioxide has become the most popular nano-photocatalyst material in the world because of its strong oxidation ability and stable chemical properties.
Cadmium sulfide (CdS) and zinc oxide (ZnO) were used as photocatalyst materials in the early days. However, due to its unstable chemical properties, it can be dissolved by light at the same time, and the dissolved harmful metal ions have certain biological toxicity. So it is rarely used as a civil photocatalytic material in developed countries, and it is still used in some industrial photocatalytic fields? [ 1]。
Properties: It is composed of CEO _ 2 (70%-90%) and ZrO _ 2 (30%-10%), forming a homogeneous compound of CEO _ 2 stabilized by ZrO _ 2, with a light yellow appearance and nano-layered structure. After aging at 1000℃ for 4 hours, the specific surface area is still large (>: 15M# G), so it can still maintain high activity at high temperature.
Uses: Suitable for high-temperature catalytic materials, such as automobile exhaust catalyst.
References:
Baidu encyclopedia-photocatalytic material
References:
Preparation and Photocatalytic Properties of China HowNet-Titanium Dioxide Hollow Composite