In situ observation of pressure modulated reversible structural changes in the graphitic domains of carbide-derived carbons

Carbons are important in a multitude of applications, and thus, the reversible control of carbon structures is of high interest. Here we report the reversible formation of graphitic structures with three distinct interlayer distances in case of two carbide-derived carbons (CDCs) loaded under hydrogen pressure observed with in situ neutron scattering methods. The formation of these graphitic structures determined with in situ neutron diffraction is brought forth by the confinement of H-2 in the porous structure when the temperature, T, is increased from T = 20 K-50 K under H-2 loading from 68 mbar to 10 bar. The confinement of the desorbing H-2 causes the pressure to increase inside the CDC structure and this increase of pressure is the cause for the reversible formation of graphitic domains. The confinement of H-2 at T = 50 K is possible due to the presence of ultramicropores and suitable curved carbon structures. The three distinct formed graphitic domains correspond to a highly pressurized, conventional highly ordered graphitic, and disoriented graphitic domains with possible H-2/H intercalation. In situ quasi-elastic neutron scattering and gas adsorption methods are used to determine the H-2 transport properties and interactions with the CDCs. (C) 2020 The Author(s). Published by Elsevier Ltd.

Automated summary

The reversible formation of graphitic structures in CDCs under hydrogen pressure is achieved by confining H-2 in the porous structure, increasing pressure and causing reversible formation of graphitic domains with distinct interlayer distances. The confinement of H-2 at elevated temperatures is possible due to ultramicropores and suitable curved carbon structures, resulting in highly pressurized, ordered, and disoriented graphitic domains with potential H-2/H intercalation. In situ neutron scattering and gas adsorption methods are used to study H-2 transport properties and interactions with CDCs.