Role of Structural Defects in the Water Adsorption Properties of MOF-801
Journal
Journal of Physical Chemistry C
Journal Volume
122
Journal Issue
10
Pages
5545-5552
Date Issued
2018
Author(s)
Abstract
The nanoporous and tunable nature of metal-organic frameworks (MOFs) has made them promising adsorbents for water adsorption applications such as water harvesting and adsorptive heat pumps. In these applications, water adsorption properties in MOFs play a crucial role. However, understanding their structural defects and how defects influence adsorption thermodynamics remains limited to date. In this work, by employing Monte Carlo techniques and first-principle density functional theory calculations, we investigate the effect of defects on the water adsorption properties in MOF-801 structures at an atomic level. Our calculations show that the adsorption isotherm in perfect MOF-801 (without defects) greatly deviates from that measured experimentally. With the introduction of defects with a high density, a reasonably good agreement can be achieved, suggesting that a high defect density in MOF-801 may be responsible for its hydrophilic adsorptive behaviors. Further, water adsorption properties in MOF-801 structures are found to depend on the spatial configuration of defects, and water condensation in nanoporous MOF-801 is identified to occur preferentially along the ?110? direction. Detailed structural characteristics (accessible volume, etc.) of MOF-801 structures and the adsorption energetics of water in the frameworks are also studied and correlated with the computed adsorption isotherms. Our findings reveal important insights into the role of defects, offering a microscopic picture to help facilitate the rational design of better MOFs for water adsorption applications. ? 2018 American Chemical Society.
Subjects
Adsorption
Adsorption isotherms
Crystalline materials
Defect density
Defects
Density functional theory
Monte Carlo methods
Organometallics
Thermodynamics
Water conservation
Adsorption energetics
Adsorption thermodynamics
First-principle density-functional theories
High defect densities
Metalorganic frameworks (MOFs)
Monte Carlo techniques
Spatial configuration
Structural characteristics
Structural properties
Type
journal article