Zare Mehdi, Saleheen Mohammad S, Singh Nirala, Uline Mark J, Faheem Muhammad, Heyden Andreas
Department of Chemical Engineering, University of South Carolina, 301 Main Street, Columbia, South Carolina 29208, United States.
Department of Chemical Engineering and Catalysis Science and Technology Institute, University of Michigan, Ann Arbor, Michigan 48109-2136, United States.
JACS Au. 2022 Aug 9;2(9):2119-2134. doi: 10.1021/jacsau.2c00389. eCollection 2022 Sep 26.
Aqueous solvation free energies of adsorption have recently been measured for phenol adsorption on Pt(111). Endergonic solvent effects of ∼1 eV suggest solvents dramatically influence a metal catalyst's activity with significant implications for the catalyst design. However, measurements are indirect and involve adsorption isotherm models, which potentially reduces the reliability of the extracted energy values. Computational, implicit solvation models predict exergonic solvation effects for phenol adsorption, failing to agree with measurements even qualitatively. In this study, an explicit, hybrid quantum mechanical/molecular mechanical approach for computing solvation free energies of adsorption is developed, solvation free energies of phenol adsorption are computed, and experimental data for solvation free energies of phenol adsorption are reanalyzed using multiple adsorption isotherm models. Explicit solvation calculations predict an endergonic solvation free energy for phenol adsorption that agrees well with measurements to within the experimental and force field uncertainties. Computed adsorption free energies of solvation of carbon monoxide, ethylene glycol, benzene, and phenol over the (111) facet of Pt and Cu suggest that liquid water destabilizes all adsorbed species, with the largest impact on the largest adsorbates.
最近已测量了苯酚在Pt(111)上吸附的水相溶剂化自由能。约1 eV的吸能溶剂效应表明，溶剂会显著影响金属催化剂的活性，这对催化剂设计具有重要意义。然而，测量是间接的，且涉及吸附等温线模型，这可能会降低所提取能量值的可靠性。计算性的隐式溶剂化模型预测苯酚吸附具有放能溶剂化效应，甚至在定性上都与测量结果不一致。在本研究中，开发了一种用于计算吸附溶剂化自由能的显式混合量子力学/分子力学方法，计算了苯酚吸附的溶剂化自由能，并使用多种吸附等温线模型重新分析了苯酚吸附溶剂化自由能的实验数据。显式溶剂化计算预测苯酚吸附的溶剂化自由能为吸能，在实验和力场不确定性范围内与测量结果吻合良好。计算得到的一氧化碳、乙二醇、苯和苯酚在Pt和Cu的(111)晶面上吸附的溶剂化自由能表明，液态水会使所有吸附物种不稳定，对最大的吸附质影响最大。
