abstract
Heterogeneously catalyzed reactions take place at the catalyst surface where, depending on the conditions and process, the reacting molecules are either in the 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 influences the atomic structure of the reactants and products as well as the 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 the solute and solvent. The present study shows that the 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 the reactants or products are significantly affected. Encouragingly, the linear equations corresponding to the Bronsted-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 the reaction on the difference surfaces, are similar in the presence or in the absence of the solvent. Despite the associated uncertainties, this suggests that BEP relationships derived without the implicit consideration of the solvent are still valid for predicting the activation energy barriers of catalytic reactions from a reaction descriptor.
keywords
GAS SHIFT REACTION; GENERALIZED GRADIENT APPROXIMATION; DENSITY-FUNCTIONAL THEORY; TOTAL-ENERGY CALCULATIONS; WATER DISSOCIATION; SURFACES; DESCRIPTORS; MOLECULES; PD(111); POINTS
subject category
Chemistry; Physics
authors
Gomes, JRB; Vines, F; Illas, F; Fajin, JLC
our authors
José R. B. Gomes
Principal Researcheracknowledgements
This work was developed within the scope of the projects CICECO-Aveiro Institute of Materials, Refs. UID/CTM/50011/2019 and POCI/01/0145/FEDER/007679, and LAQV@REQUIMTE, Refs. UID/QUI/50006/2019 and POCI/01/0145/FEDER/007265, financed by national funds through the Fundacao para a Ciencia e a Tecnologia (FCT/MCTES) and co-financed by FEDER under the PT2020 Partnership Agreement. The research carried out at the Universitat de Barcelona was supported by the Spanish MINECO/FEDER CTQ2015-64618-R and, in part, by Generalitat de Catalunya (grants 2017SGR13 and XRQTC). F. V. thanks MINECO for a postdoctoral Ramon y Cajal (RyC) research contract (RYC-2012-10129), and F. I. acknowledges additional support from the 2015 ICREA Academia Award for Excellence in University Research. Additional financial support from Spanish Ministerio de Ciencia, Investigacion y Universidades (MICIUN) through the Excellence Maria de Maeztu program (grant MDM-2017-0767) is also fully acknowledged.