The structure and properties of methane adsorbed on graphitized carbon black determined by neutron diffraction

A simulation study of the low temperature phase diagram of the methane monolayer on graphite: a test of potential energy functions

The TraPPE-EH model reveals the two patterns of commensurate monolayer and the mechanism of commensurate–incommensurate transition in a certain temperature range.

Methane storage in molecular nanostructures

We survey various molecular structures which have been proposed as possible nanocontainers for methane storage. These are molecular structures that have been investigated through either experiments, molecular dynamics simulations or mathematical modelling. Computational simulation and mathematical modelling play an important role in predicting and verifying experimental outcomes, but both have their limitations. Even though recent advances have greatly improved computations, due to the large number of atoms and force field calculations involved, computational simulations can still be time consuming as compared to an instantaneous mathematical modelling approach. On the other hand, underlying an ideal mathematical model, there are many assumptions and approximations, but such modelling often reveals the key physical parameters and optimal configurations. Here, we review methane adsorption for three conventional nanostructures, namely graphite, single and multi-walled carbon nanotubes, and nanotube bundles (including interstitial and groove sites), and we survey methane adsorption in other molecular structures including metal organic frameworks. We also include an examination of minimum binding energies, equilibrium distances, gravimetric and volumetric uptakes, volume available for adsorption, as well as the effects of temperature and pressure on the adsorption of methane onto these molecular structures.

Neutron investigations of rotational motions in monolayer and multilayer films at the interface of MgO and graphite surfaces

Recent experimental investigations of the rotational motion of methane and molecular hydrogen using inelastic neutron scattering (INS) measurements in combination with thermodynamic techniques have provided a unique view of the evolution of the interaction of these two molecules with the MgO (100) surface and graphite basal plane. Despite significant differences in the chemical and physical properties and surface symmetry of these two adsorbents, the dynamical behavior of the adsorbed films is remarkably similar. The interaction of a CH4 monolayer solid with MgO and graphite, as monitored by the behavior of the J = 0 --> J = 1 free rotor transition, is so strong that there is no evidence for unhindered rotation of the molecule below 20 K. Using this same transition as a probe, H2 monolayer solids exhibit nearly free or significantly hindered motion on graphite and MgO (100) surfaces, respectively. Investigations of CH4 and H2 multilayer films on MgO find that once the film thickness exceeds approximately 3 layers, the molecule-molecule interactions predominantly determine the dynamical properties of the molecular film furthest from the surface. INS signals indicate that the dynamical motion in thicker films is closely related to that observed in the bulk system. The results of these studies serve as a valuable pathway for developing a qualitatively accurate description of the potential energy surfaces that govern the microscopic properties of these systems.