Role of adsorption activation energy in heat change of irreversible dissociative adsorption with coverage on energetically heterogeneous solid surface

The differential heat of gas adsorption on solid surface is often used to determine surface energy heterogeneity. In this paper, the theoretical analysis of irreversible dissociative adsorption on double-site surfaces shows that the change of differential adsorption heat with coverage is strongly dependent on the difference of adsorption activation energies between active sites. Furthermore, it was found that a discontinuous double-site surface can exhibit continuous changes of differential adsorption heat with coverage. This indicates that the distribution functions obtained from the relationship between differential adsorption heat and coverage may provide an incorrect characteristic of surface energetic heterogeneity.

The change of differential adsorption heat with coverage on double-site surface is strongly dependent on the difference of adsorption activation energies between active sites. Furthermore, a discontinuous double-site surface can exhibit continuous changes of differential adsorption heat with coverage. This indicates that the distribution functions obtained from the relationship between differential adsorption heat and coverage may provide an incorrect characteristic of surface energetic heterogeneity.Figure optionsDownload as PowerPoint slide