A Monte Carlo simulation study of the effect of carbon topology on nitrogenadsorption on graphite, a nanotube bundle, C60 fullerite, C168 schwarzite, and a nanoporous carbon

Abstract

The effect of carbon topology on nitrogen adsorption at zero coverage on a variety of carbonaceous materials: graphite, a nanotube bundle, C₆₀ fullerite, C₁₆₈ schwarzite, and a nanoporous carbon is studied systematically using full atomistic Monte Carlo simulations. The pairwise additive site–site Lennard-Jones potential of Bojan and Steele is used to model the carbon−nitrogen interaction of adsorbent−adsorbate. The Henry constant is found to increase in the order of graphite < nanotube bundle < C₆₀ fullerite < C₁₆₈ schwarzite < nanoporous carbon, and the isosteric heat of adsorption increases in the order of graphite < nanotube bundle < C₁₆₈ schwarzite < C₆₀ fullerite < nanoporous carbon. The latter order is consistent with the degree of curvature, as characterized by the carbon coordination number around nitrogen in favorable adsorption sites. With increasing temperature, the Henry constant significantly decreases on all the carbonaceous materials studied, while the isosteric heat remains nearly constant on graphite, nanotube bundle, and C₆₀ fullerite, decreases slightly on C₁₆₈ schwarzite, and to a greater extent on nanoporous carbon.