%0 Journal Article
%A Krause, Simon
%A Bon, Volodymyr
%A Du, Hongchu
%A Dunin-Borkowski, Rafal E
%A Stoeck, Ulrich
%A Senkovska, Irena
%A Kaskel, Stefan
%T The impact of crystal size and temperature on the adsorption-induced flexibility of the Zr-based metal–organic framework DUT-98
%J Beilstein journal of nanotechnology
%V 10
%@ 2190-4286
%C Frankfurt, M.
%I Beilstein-Institut zur Förderung der Chemischen Wissenschaften
%M FZJ-2020-02774
%P 1737 - 1744
%D 2019
%X In this contribution we analyze the influence of adsorption cycling, crystal size, and temperature on the switching behavior of the flexible Zr-based metal–organic framework DUT-98. We observe a shift in the gate-opening pressure upon cycling of adsorption experiments for micrometer-sized crystals and assign this to a fragmentation of the crystals. In a series of samples, the average crystal size of DUT-98 crystals was varied from 120 µm to 50 nm and the obtained solids were characterized by X-ray diffraction, infrared spectroscopy, as well as scanning and transmission electron microscopy. We analyzed the adsorption behavior by nitrogen and water adsorption at 77 K and 298 K, respectively, and show that adsorption-induced flexibility is only observed for micrometer-sized crystals. Nanometer-sized crystals were found to exhibit reversible type I adsorption behavior upon adsorption of nitrogen and exhibit a crystal-size-dependent steep water uptake of up to 20 mmol g−1 at 0.5 p/p0 with potential for water harvesting and heat pump applications. We furthermore investigate the temperature-induced structural transition by in situ powder X-ray diffraction. At temperatures beyond 110 °C, the open-pore state of the nanometer-sized DUT-98 crystals is found to irreversibly transform to a closed-pore state. The connection of crystal fragmentation upon adsorption cycling and the crystal size dependence of the adsorption-induced flexibility is an important finding for evaluation of these materials in future adsorption-based applications. This work thus extends the limited amount of studies on crystal size effects in flexible MOFs and hopefully motivates further investigations in this field.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:31501745
%U <Go to ISI:>//WOS:000482478100001
%R 10.3762/bjnano.10.169
%U https://juser.fz-juelich.de/record/878318