Computationally supported neutron scattering study of natural shungite, anthraxolite, and synthetic carbon black

TL;DR

This study uses neutron scattering techniques to analyze the structure and hydrogen content of natural and synthetic amorphous carbons, revealing nanographite-like structures and adsorbed water within pores.

Contribution

It provides a novel neutron scattering-based classification of sp2 amorphous carbons considering their hydrogenation and structural features.

Findings

All samples exhibit nanographite-like structures with ~2.5 nm graphene units.

Hydrogen atoms are present in the BSU framing areas and water is adsorbed in pores.

INS spectra can classify carbons based on hydrogen content and heavy atom dynamics.

Abstract

A set of sp2 amorphous carbons involving natural mineral shungite carbon and antraxolite as well as two synthetic carbon blacks were investigated by using neutron powder diffraction and inelastic neutron scattering at low temperature. NDP revealed nanographite-like structure of all the samples, stacks of which are formed by basic structure units representing framed graphene molecules of ~2.5 nm in lateral dimension. INS study showed the presence of hydrogen atoms in the BSU framing area as well as of adsorbed water in the samples pores. Simulated INS spectra of adsorbed water showed its mono-layer disposition within the pores of the studied amorphics. Due to BSUs radical character, their INS spectra were simulated in the framework of both spin-nondependent (DFT) and spin-dependent (UHF) molecular dynamics. The obtained results allowed suggesting a specific INS classification of sp2 amorphous carbons with respect to their hydrogeneousness based on H-standard INS spectra, on the one side, and riding-stimulated spectrum of heavy atoms, on the other.