文献类型：期刊文献

英文题名：Energy Landscape of Water and Ethanol on Silica Surfaces

作者：Wu, Di[1,2];Guo, Xiaofeng[1,2,3];Sun, Hui[4];Navrotsky, Alexandra[1,2]

机构：[1]Univ Calif Davis, Peter A Rock Thermochem Lab, One Shields Ave, Davis, CA 95616 USA;[2]Univ Calif Davis, NEAT ORU, Davis, CA 95616 USA;[3]Los Alamos Natl Lab, Earth Syst Observat, Earth & Environm Sci Div, Los Alamos, NM 87545 USA;[4]E China Univ Sci & Technol, State Key Lab Chem Engn, Shanghai 200237, Peoples R China

年份：2015

卷号：119

期号：27

起止页码：15428

外文期刊名：JOURNAL OF PHYSICAL CHEMISTRY C

收录：;EI(收录号：20152801027330);WOS:【SCI-EXPANDED(收录号:WOS:000357964900067)】；

基金：The calorimetric work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Grant DE-FG02-97ER14749. The authors thank Bruce C. Gates for invaluable discussion during Di Wu's Ph.D. exit seminar, which initiated this study. We also thank Krasen Kovachev and Sergey V. Ushakov for instrumental support.

语种：英文

外文关键词：Binding sites - Silica - Hydrophobicity - Glass - Surface chemistry - Enthalpy

摘要：Fundamental understanding of small molecule silica surface interactions at their interfaces is essential for the scientific, technological, and medical communities. We report direct enthalpy of adsorption (Delta h(ads)) measurements for ethanol and water vapor on porous silica glass (CPG-10), in both hydroxylated and dehydroxylated (hydrophobic) forms. The results suggest a spectrum of energetics as a function of coverage, stepwise for ethanol but continuous for water. The zero-coverage enthalpy of adsorption for hydroxylated silica shows the most exothermic enthalpies for both water (-72.7 +/- 3.1 kJ/mol water) and ethanol (-78.0 +/- 1.9 kJ/mol ethanol). The water adsorption enthalpy becomes less exothermic gradually until reaching its only plateau (-20.7 +/- 2.2 kJ/mol water) reflecting water clustering on a largely hydrophobic surface, while the enthalpy of ethanol adsorption profile presents two well separated plateaus, corresponding to strong chemisorption of ethanol on adsorbate-free silica surface (-66.4 +/- 4.8 kJ/mol ethanol), and weak physisorption of ethanol on ethanol covered silica (-4.0 +/- 1.6 kJ/mol ethanol). On the other hand, dehydroxylation leads to missing water-silica interactions, whereas the number of ethanol binding sites is not impacted. The isotherms and partial molar properties of adsorption suggest that water may only bind strongly onto the silanols (which are a minor species on silica glass), whereas ethanol can interact strongly with both silanols and the hydrophobic areas of the silica surface.