Kinetics of dissociative hydrogen adsorption on the (1 0 0) nickel single crystal face: a statistical rate theory approach

For its importance for many catalytic reactions, the dissociative adsorption of hydrogen on the nickel surfaces has been one of the most extensively investigated subjects during the last few decades. Here the pressure and coverage dependence of that adsorption kinetics is of a particular importance. Meanwhile, although relevant experimental data were measured as long as 30 years ago, no theoretical expressions have been proposed so far which could quantitatively describe the pressure and coverage dependence of that dissociative adsorption kinetics. The attempts based on the classical TAAD approach (theory of activated adsorption/desorption) resulted in a clearly seen failure. Here a new description is proposed based on the SRT (statistical rate theory) approach, linking the features of that dissociative adsorption to the chemical potentials in the gas and adsorbed phases. Based on that approach, theoretical expressions are developed, and next used to analyze the kinetics of hydrogen dissociative adsorption on the single crystal face Ni(1 0 0) surface. By using the same set of adsorption parameters an excellent simultaneous fit is obtained of both kinetic isotherms measured at different pressures, and equilibrium adsorption isotherms measured at different temperatures. These parameters agree well with the related values found for this system in the quantum mechanical calculations. # 2004 Elsevier B.V. All rights reserved