TY - JOUR
T1 - Interplay of Confinement and Surface Energetics in the Interaction of Water with a Metal-Organic Framework
AU - Wu, Di
AU - Guo, Xiaofeng
AU - Sun, Hui
AU - Navrotsky, Alexandra
N1 - Funding Information:
This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Grant DE-FG02-05ER15667. The Cornell High Energy Synchrotron Source is supported by National Science Foundation Award DMR-0936384. H.S. thanks the Natural Science Foundation of Shanghai for the financial support (No. 16ZR1408100).
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/4/21
Y1 - 2016/4/21
N2 - 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.
AB - 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.
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U2 - 10.1021/acs.jpcc.5b12239
DO - 10.1021/acs.jpcc.5b12239
M3 - Article
AN - SCOPUS:84964714880
SN - 1932-7447
VL - 120
SP - 7562
EP - 7567
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 14
ER -