Effect of the Structure and Morphology of Natural, Synthetic and Post-processed Graphites on Their Dispersibility and Electronic Properties

Abstract

Twenty-two different graphite grades of the families natural, synthetic, intercalated, expanded, amorphous, and turbostratic graphite, as well as platelets and activated carbon, were analyzed on their dispersibility in N-methylpyrrolidone, cyclohexylpyrrolidone and water-sodium cholate solution. They were characterized for their properties (grain size, density, purity, surface area, pH in water) and morphology. Thermogravimetric analysis, Raman spectroscopy studies, and electrical conductivity measurements were also used. XRPD followed by a Rietveld refinement provided information on the amounts of the rhombohedral (3R) and hexagonal (2H) phases for the crystalline part of the material and the interlayer distances. The properties of graphites favoring better dispersibility are: small grain size and bulk density, neutral pH in water. The electrical conductivity in inversely proportional to the Raman D-band intensity and is highest for the graphites with shortest interlayer spacing. The D-, G-and 2D-bands in the Raman spectra of graphites are in an exponential relation.

Electron transfer kinetics on natural crystals of MoS2 and graphite

“…However, the isolation of graphene initiated significant advances in preparation of high-quality graphite samples using mechanical exfoliation. [35][36][37] Surprisingly, the fundamental electrochemistry of natural crystalline graphite has barely been explored (with the exception of ionic intercalation) and much of what is understood about basal/edge plane electroactivity has been learned from experiments on HOPG. Mechanical exfoliation of natural graphite, however, can now yield single-crystal monoand multi-layer flakes reaching millimetre lateral dimensions.…”

Statistical Raman Microscopy and Atomic Force Microscopy on Heterogeneous Graphene Obtained after Reduction of Graphene Oxide

“…This is a consequence of the chemical oxidation and potentially due to the heterogeneity in flake size of graphite. 9 Therefore, the defects in GO and graphene, respectively, are unevenly distributed. It turned out that Scanning-Raman-Micropscopy (SRM) is a versatile 5 tool to determine and visualize the heterogeneity of graphene samples and to make defect densities visible, as we demonstrated for structured single flakes before.…”

Towards scale‐up of graphene production via nonoxidizing liquid exfoliation methods

“…This study allowed them to clearly identify that the smaller graphite particles (relative to larger ones) can be more readily dispersed in a solvent and form a more stable dispersion. This can be even further enhanced if graphite of small bulk density and pH close to neutral in water is used …”