A new approach to turbostratic carbon production via thermal salt-assisted treatment of graphite

Here graphite was found to undergo carbon/carbonate gasification at 800 degrees C, resulting in exfoliation of graphite to form turbostratic carbon. The lattice distance of graphene sheets in graphite are shown to undergo marked changes following treatment with molten ternary eutectic carbonate (Li2CO3: 43.5%, Na2CO3: 31.5%, K2CO3: 25%) during slow temperature ramping rates (5 degrees C/min) under N2 at temperatures above 750 degrees C. Initial findings suggest that approximately 50 wt% of graphite experiences interlayer expansion. The conventional d spacing of 0.34 nm is modified to a range of intervals between 0.41 nm and 1.22 nm. As a consequence of high operational temperature (800 degrees C), cations (Li+, Na+ and K+) as well as potentially the anion (CO32-) intercalate between graphitic layers and overcome Van der Waal force between layers. Employing a pressurized N2 environment of 5 bar and 10 bar successfully controls carbonate vaporization and decomposition, as well as inducing ordered layer manipulation to exfoliate more graphite planes from the edges towards deeper levels of the particles. Exploring parameters of both carbonate loading and treatment time in addition to pressure demonstrate that this work opens up a rich selection of parameters that can be used to produce carbons with tuned properties from graphite.

Automated summary

Carbonate gasification causes exfoliation of graphite to form turbostratic carbon at 800°C. Treatment with molten ternary eutectic carbonate leads to significant changes in the lattice distance of graphene sheets in graphite above 750°C. Approximately 50% of graphite experiences interlayer expansion, modifying the conventional d spacing of 0.34 nm to intervals between 0.41 nm and 1.22 nm.