Efecto de la Curvatura de la Superficie en la Adsorción de Gases Simples sobre Materiales Carbonosos usando la Teoría del Funcional de la Densidad (DFT)

Abstract

ResumenEn el presente trabajo se realizaron cálculos de la adsorción de nitrógeno, metano e hidrógeno sobre superficies carbonosas que poseen distintas curvaturas. Se utilizó la teoría del funcional de la densidad (DFT) mediante el funcional PW91PW91 junto a un conjunto de bases 6-31G (d, p). Los resultados obtenidos fueron ajustados al potencial de Lennard-Jones 12-6 para obtener los parámetros de interacción. Los parámetros que resultan de ajustar un potencial 12-6 de LennardJones no muestran ninguna dependencia importante con la curvatura de los nanotubos en el rango considerado Palabras clave: metano, nitrógeno, adsorción de gases, nanotubos, materiales carbonosos Effects of the Surface Curvature on the Adsorption of Simple Gases over Carbonaceous Materials using the Density Functional Theory (DFT) AbstractIn this paper calculations of the adsorption of nitrogen, methane and hydrogen on carbonaceous surfaces that have different curvatures are presented. The density functional theory (DFT) was used including a functional PW91PW91 along with a set of 6-31G basis (d, p). The results were adjusted to the potential of 12-6 Lennard-Jones to get the interaction parameters. The parameters of the 12-6 Lennard-Jones potential show no important dependency on the curvature of the nanotubes in the range considered in this study.

Comparative Study of Methane Adsorption on Single-Walled Carbon Nanotubes

“…We can see for external of G and S sites that they are better represented by (7,7) and (12,12) nanotubes and that the interaction energy corresponding to G sites is approximately twice that of S sites, in good agreement with experiments and first principles calculations. ,,, For internal T and IC sites, the agreement between MM+ and DFT calculations is somehow poorer, probably due to the different cluster employed. In spite of these differences, both results showed the same trends when the tube diameter is increased.…”

“…We adopted the Martin and Siepmann model to calculate the adsorbate−adsorbate interactions, because of its demonstrated capacity for reproducing experimental data over a wide range of pressures and temperatures . Instead of changing the potentials, in order to match experimental values at some coverage region, we adopted graphite parameters for the nanotubes and clusters, because we have previously verified that the dependence of these interaction parameters on curvature is negligible.…”