Do you know what are the graphene detection methods?
Jan 12 , 2023
With the rapid development of science and technology, there are various methods of preparing graphene, but the quality of graphene produced by each preparation method varies greatly. Therefore, different graphenes and their different properties are distinguished, and then they are distinguished in the application direction of graphene. Giving full play to the special properties of different graphenes is also a way to rationally utilize graphenes.
At present, graphene detection instruments are mainly divided into image and atlas. The image is mainly based on optical microscope, scanning electron microscope (SEM), transmission electron microscope (TEM), and atomic force microscope (AFM), while the atlas is mainly based on Raman spectroscopy. (Raman), infrared spectroscopy (IR), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet spectroscopy (UV) as representatives, each detection method has its own advantages and limitations, next Let's take a brief look at the three detection methods.
Specific detection method
1. Atomic Force Microscope (AFM)
AFM is a scanning probe microscope, which can detect the fine shape and exact thickness information of graphene very accurately. Its micro-cantilever can sense the interaction between the needle tip and the sample to cause deformation, and then detected by the laser reflection system. The cantilever bends and deforms, which indirectly measures the force between the tip and the sample to reflect the surface topography of the sample. Therefore, this method mainly detects the thickness of the sheet, the topography such as surface relief and steps, and the measurement of the height difference between layers.
But its limitation is that the efficiency is low, and because there are often some adsorbates on the surface of graphene, which will make the measured thickness of graphene slightly larger than its actual thickness.
2. Raman Spectroscopy (Raman)
As one of the commonly used, fast, non-destructive and high-resolution techniques for detecting carbon materials, Raman spectroscopy is also a no-brainer for the detection of graphene powder materials. We can judge the number of layers of graphene through Raman spectroscopy , defects and other information.
The Raman spectrum of graphene powder material consists of many peaks, mainly G peak, D peak and 2D peak. The G peak can reflect the layer number characteristics of graphene, but it is easily affected by factors such as graphene surface stress. The D peak is mainly used to characterize structural defects or edge states in graphene products. The 2D peak is mainly used to characterize the interlayer stacking of microscopic carbon atoms in graphene products, and its peak frequency is also affected by the laser wavelength. The electron dispersion of multilayer and single-layer graphene is different, leading to a clear difference in Raman spectra.
Raman spectroscopy has unique advantages in the detection of graphene layers. The perfect single Lorentzian second-order Raman peak (G' peak) is a simple and effective method for determining single-layer graphene.
3. X-ray Diffraction (XRD)
X-ray diffraction, which is mainly used to characterize the two-dimensional crystal structure of graphene materials, the interplanar spacing and lattice parameters of graphene, etc. At the same time, XRD can conduct semi-quantitative analysis and evaluation on the degree of reduction and defects of graphene powder.
Although the XRD patterns of graphene prepared by different methods are different, it can be used as an auxiliary means to characterize the structure of graphene.
Through comprehensive measurement of various methods, the number of layers, purity, defects and other related values of graphene can be measured very accurately. At the same time, as graphene research becomes more and more popular, more graphene measurement methods will appear in the future, and the relevant test result analysis standards will be more complete and specific, so that different graphene can be applied to different fields with high quality. Production and life create more possibilities and driving forces.
