Ultraviolet Raman spectra: The reasonable method of evaluating coal pyrolysis graphitization

Abstract

Raman spectrum is a common method of evaluating the graphitization degree of carbon materials. However, there is still some controversy over its evaluation for coal graphitization, i.e., whether large ID/IG means a high graphitization degree of coal. This work uses an ultraviolet (UV) Raman spectrum to find a better index of graphitization degree. The T peak (sp3 sites) of coal was first directly detected. The IT/IG and ID/IG decrease after pyrolysis in UV Raman spectra at 266 nm, which shows that the sp3 site relative content decreases and the sp2 site relative content increases. Moreover, the absolute value of the D band dispersion slopes as the excitation wavelength increases and the D peak width decreases, which shows that the coal gets more orderly after pyrolysis. The position difference (G–D) decreases and the G peak width increases after pyrolysis in UV–Vis Raman spectra, indicating the decomposition of vitrinite in coal. The 2D′ peak decreased after pyrolysis. These parameters in multi-wavelength Raman spectra can be used to evaluate the structure of coal.

Study of graphene oxide complexed hemicucurbit[6]uril on polypropylene composites: Crystallization behavior, foaming performance, and mechanical properties

“…The intensity ratio of the D band (disordered, ~1350 cm −1 ) and G band (graphitic, ~1600 cm −1 ) peaks is a common index that characterizes graphitization degree. This result was consistent with previously reported values 25 . When GO compounded with HQ6, the corresponding characteristic peaks of the D and G bands changed to 1603 and 1338 cm −1 , respectively, which confirmed the chemical bond between GO and HQ6.…”

“…This result was consistent with previously reported values. 25 When GO compounded with HQ6, the corresponding characteristic peaks of the D and G bands changed to 1603 and 1338 cm À1 , respectively, which confirmed the chemical bond between GO and HQ6.…”

Molecular dynamics simulation of the amorphous graphite-like membrane deposited on ideal graphite substrate

“…PyG has controllable high orientation and anisotropy due to the tendency of the interlayer planes to grow parallel to the substrate surface. [1][2][3] PyG has good heat resistance, thermal and electrical conductivity and stable chemical properties, and widely used in propellant rocket nozzles, gates of electronic tubes and various protective coatings for electronic devices. [4][5][6] Microstructural studies of PyG show that PyG graphite layers are stacked oen in a non-ideal ABAB stacking manner, i.e., in a disordered layer stacking in the [001] direction, and thus the general PyG graphite interlayer distance is slightly greater than the layer spacing of 3.4 Å for ideal singlecrystal graphite.…”