Implicit solvent effects in the determination of Bronsted-Evans-Polanyi relationships for heterogeneously catalyzed reactions

Abstract

Heterogeneous catalyzed reactions take place at the catalyst surface where, depending on the conditions and process, the reacting molecules are either in gas or liquid phase. In the latter case, computational heterogeneous catalysis studies usually neglect solvent effects. In this work, we systematically analyze how the electrostatic contribution to solvent effects influence the atomic structure of reactants and products as well as adsorption, activation and reaction energy for the dissociation of water on several planar and stepped transition metal surfaces. The solvent effects were accounted for through an implicit model that describes the effect of electrostatics, cavitation, and dispersion on the interaction between solute and solvent. The present study shows that activation energy barriers are only slightly influenced by the inclusion of the electrostatic solvent effects accounted for in a continuum solvent approach whereas the adsorption energies of reactants or products are significantly affected. Encouragingly, the linear equations corresponding to the Brønsted-Evans-Polanyi relationships (BEPs) relating the activation energies for the dissociation reaction with a suitable descriptor, e.g. the adsorption energies of the products of reaction on the difference surfaces, are similar in the presence or in the absence of the solvent. This suggests that BEP relationships derived without the implicit consideration of the solvent are still valid for predicting activation energy barriers of catalytic reactions from a reaction descriptor.