Gomes José R B, Viñes Francesc, Illas Francesc, Fajín José L C
CICECO - Aveiro Institute of Materials, Departamento de Química, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Phys Chem Chem Phys. 2019 Aug 28;21(32):17687-17695. doi: 10.1039/c9cp02817j. Epub 2019 Jul 31.
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 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 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.
多相催化反应发生在催化剂表面，根据条件和过程的不同，反应分子处于气相或液相。在后一种情况下，计算多相催化研究通常忽略溶剂效应。在这项工作中，我们系统地分析了溶剂效应的静电贡献如何影响反应物和产物的原子结构，以及水在几个平面和阶梯状过渡金属表面解离的吸附、活化和反应能量。通过一个描述静电、空化和色散对溶质与溶剂相互作用影响的隐式模型来考虑溶剂效应。本研究表明，采用连续介质溶剂方法考虑静电溶剂效应时，活化能垒仅受到轻微影响，而反应物或产物的吸附能则受到显著影响。令人鼓舞的是，在有或没有溶剂的情况下，与布朗斯特 - 埃文斯 - 波拉尼关系（BEP）相对应的线性方程相似，该方程将解离反应的活化能与合适的描述符相关联，例如反应产物在不同表面上的吸附能。尽管存在相关的不确定性，但这表明在未隐含考虑溶剂的情况下得出的BEP关系对于根据反应描述符预测催化反应的活化能垒仍然有效。
