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The Impact of Mesopores on the Mechanical Stability of HKUST‐1: A Multiscale Investigation
Author(s) -
Dürholt Johannes P.,
Keupp Julian,
Schmid and Rochus
Publication year - 2016
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201600566
Subject(s) - mesoporous material , microporous material , void (composites) , porosity , chemistry , volume fraction , specific surface area , gravimetric analysis , nanotechnology , composite material , materials science , biochemistry , organic chemistry , catalysis
Correlated missing node defects can lead to mesoporosity in MOFs. In order to investigate the effect of such cavities in the microporous crystalline material, spherical pores of increasing size were cut into HKUST‐1, and the resulting inner surface was completely saturated. Our recently developed coarse‐grained force field was used to relax these systems and to assess the mechanical stability by computing the bulk moduli. In a multiscale fashion, atomistic models were generated systematically from the coarse‐grained relaxed structures in order to determine void fraction, surface area, and the relative mesoporous void volume. Despite the presence of mesopores with large radii of above 20 Å, the lattice parameters shrink only by a negligible amount. The bulk moduli are reduced, but overall a sufficient mechanical stability is found, consistently with experimental observations. Interestingly, for a fixed amount of defect degree, and thus mesoporous void volume, larger cavities lead to higher mechanical stability. For small mesopores in the size range below that of a HKUST‐1 unit cell we observe unexpected trends due to the additional surface area generated by saturating the inner surface of the mesopore. With a large number of small mesopores, this can lead to an effective increase in the gravimetric surface area.