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Title: Interplay of confinement and surface energetics in the interaction of water with a metal–organic framework

Here, the enthalpy of water adsorption (Δh) on the metal–organic framework (MOF) HKUST-1 has been determined directly by calorimetry. The most exothermic value of Δh [–119.4 ± 0.5 kJ/(mol of water)] occurs at zero coverage and perhaps represents water confinement in the smallest (4-Å) cages. An intermediate Δh value of –50.2 ± 1.8 kJ/(mol of water) at higher loading probably corresponds to the binding of water on the available Cu nodes and subsequent filling of the largest (11-Å) pores. The weakest interactions take place in the medium (10-Å) cages, showing weak inclusion of water clusters in a limited hydrophobic environment. By combining ethanol adsorption calorimetry, mathematical analysis of the slope of the water adsorption isotherm, and the differential enthalpy of water adsorption curve, we are able not only to develop an approach to separate energetically multistage guest–host interactions in complex MOF architectures but also to distinguish a sequence of interactions with very similar energetic effects.
Authors:
 [1] ;  [2] ;  [3] ;  [1]
  1. Univ. of California, Davis, CA (United States)
  2. Univ. of California, Davis, CA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. East China Univ. of Science and Technology, Shanghai (China)
Publication Date:
OSTI Identifier:
1247324
Report Number(s):
LA-UR--15-25804
Journal ID: ISSN 1932-7447
Grant/Contract Number:
FG02-05ER15667; 21201063; AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 120; Journal Issue: 14; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Research Org:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY