Influence of surface heterogeneity on thermodynamics of adsorption. Computer simulation study.

Two models of adsorption on heterogeneous surfaces are considered and compared to analogous models for adsorption on homogeneous surfaces. One model is one-dimensional adsorption of hard rods on a Line in a random external field (comparable to the Tonks gas on a line). Another is adsorption of soft repulsive spheres on amorphous carbon, compared to the spheres on graphite. For the one-dimensional model, the distribution of the adsorption sites in energy is qualitatively the same as for a real heterogeneous surface. In both cases the variation of the differential entropy of adsorption vs. coverage on heterogeneous surfaces is shown to be considerably smaller than on homogeneous ones.