Neutron scattering study of the terminating protons in the basic structural units of non-graphitising and graphitising carbons

Abstract

The proton-related fine structure of inelastic neutron spectra of glassy carbon, pure anthracite coal, furnace black and activated carbon has been evaluated using periodic density-functional perturbation theory models of graphene sheets with isolated (H1), vicinal hydrogen (H2) and mixed (H1, H2) termination. Significant differences in the out-of-plane aryl C-H bending/wagging mode region were observed which are not simply numerically correlated with the hydrogen content but with the fine structure of the carbons of different origin and production technology. The basic structural units in glassy carbon type 1 appear to be more uniform than in other carbons, H1 and H2 terminations seems to occur in distinct domains and a mixture of the types is sparse. The neutron spectra of type 2 material and of acetylene blacks of low hydrogen content show similarity to the spectrum of pure graphite, however, transmission electron microscopy reveals distinct differences in morphology at the nanoscale.