DFT/CC investigation of physical adsorption on a graphite (0001) surface

Abstract

The physical adsorption of molecules (C(2)H(2), C(2)H(4), C(2)H(6), C(6)H(6), CH(4), H(2), H(2)O, N(2), NH(3), CO, CO(2), Ar) on a graphite substrate has been investigated at the DFT/CC level of theory. The calculated DFT/CC interaction energies were compared with the available experimental data at the zero coverage limit. The differences between the DFT/CC results and experiment are within a few tenths of kJ mol(-1) for the most accurate experimental estimates (Ar, H(2), N(2), CH(4)) and within 1-2 kJ mol(-1) for the other systems (C(2)H(2), C(2)H(4), C(2)H(6), C(6)H(6), CO, CO(2)). For water-graphite and ammonia-graphite complexes, DFT/CC predicts interaction energies of 13 kJ mol(-1) in good accord with the DF-DFT-SAPT and DFT-D calculations. The relevance of the results obtained with the coronene model for the description of the physisorption on graphite surface was also studied.

Thermal Reactions of Oxygen Atoms With Alkenes at Low Temperatures on Interstellar Dust

“…For example, the interaction energy between C 2 H 4 and coronene (hollow site) is calculated to be 17.4 kJ mol −1 , equivalent to 2088 K (Rubes et al 2010) and the interaction energy between O atoms and pyrene (bridge site) is calculated to be 11.6 kJ mol −1 (Bergeron et al 2008), equivalent to 1395 K. These calculated values agree well with those we extract from our data. Caution should be exercised in interpreting our experimental desorption energies as simple values for adsorption on a graphite substrate.…”

“…In our model we use a value of A Des,O of 3.10 × 10 12 s −1 , a value derived from the potential energy curve calculated (Bergeron et al 2008) for the adsorption of O atoms at a bridge site of pyrene. For A Des,C 2 H 4 we use a value of 2.42 × 10 12 s −1 (Rubes et al 2010). Unfortunately, to our knowledge, no value of A for the adsorption of C 2 H 4 on a graphite surface is available, and so we have assumed the value of A Des,C 2 H 4 also governs the desorption of C 3 H 6 (A Des,C 3 H 6 = A Des,C 2 H 4 ).…”

Methane in carbon nanotube: molecular dynamics simulation

“…These results suggest that the tripod orientation is characteristic for molecules near the CNT wall, but molecules localised further from the nanotube surface do not show any preferred orientation. One must note that for ideal tripod orientation the angles, which C-H bonds form with the normal to the CNT surface are following: one of 180° and three ones of 70.5°, and such orientation is suggested by studies of methane adsorbed on a graphite surface using the classical MD simulation [47,54] and DFT method [49,55]. In other words the methane molecules in CNT are tilted with respect to the ideal tripod orientation.…”

First principles investigation of hydrogen physical adsorption on graphynes' layers

“…The interaction of nonpolar H 2 molecules with carbon-based substrates is mainly the London dispersion and expected values for its binding energy with a single(multi)-layer are around 50 meV [14][15][16]. The H 2 -graphdiyne single-layer interaction was previously theoretically investigated [8,17] by means of dispersion-corrected density functional theory (DFT) approaches but the focus was mostly on the penetration barrier in order to propose graphdiyne as an optimal platform for hydrogen purification.…”