Dataset Information

Increased CO₂ Affinity and Adsorption Selectivity in MOF-801 Fluorinated Analogues.

ABSTRACT: The novel Zr^IV-based perfluorinated metal-organic framework (PF-MOF) [Zr₆O₄(OH)₄(TFS)₆] (ZrTFS) was prepared under solvent-free conditions using the commercially available tetrafluorosuccinic acid (H₂TFS) as a bridging ditopic linker. Since H₂TFS can be seen as the fully aliphatic and perfluorinated C₄ analogue of fumaric acid, ZrTFS was found to be isoreticular to zirconium fumarate (MOF-801). The structure of ZrTFS was solved and refined from X-ray powder diffraction data. Despite this analogy, the gas adsorption capacity of ZrTFS is much lower than that of MOF-801; in the former, the presence of bulky fluorine atoms causes a considerable window size reduction. To have PF-MOFs with more accessible porosity, postsynthetic exchange (PSE) reactions on (defective) MOF-801 suspended in H₂TFS aqueous solutions were carried out. Despite the different H₂TFS concentrations used in the PSE process, the exchanges yielded two mixed-linker materials of similar minimal formulae [Zr₆O₄(μ₃-OH)₄(μ₁-OH)_2.08(H₂O)_2.08(FUM)_4.04(HTFS)_1.84] (PF-MOF1) and [Zr₆O₄(μ₃-OH)₄(μ₁-OH)_1.83(H₂O)_1.83(FUM)_4.04(HTFS)_2.09] (PF-MOF2) (FUM^2- = fumarate), where the perfluorinated linker was found to fully replace the capping acetate in the defective sites of pristine MOF-801. CO₂ and N₂ adsorption isotherms collected on all samples reveal that both CO₂ thermodynamic affinity (isosteric heat of adsorption at zero coverage, Q_st) and CO₂/N₂ adsorption selectivity increase with the amount of incorporated TFS^2-, reaching the maximum values of 30 kJ mol^-1 and 41 (IAST), respectively, in PF-MOF2. This confirms the beneficial effect coming from the introduction of fluorinated linkers in MOFs on their CO₂ adsorption ability. Finally, solid-state density functional theory calculations were carried out to cast light on the structural features and on the thermodynamics of CO₂ adsorption in MOF-801 and ZrTFS. Due to the difficulties in modeling a defective MOF, an intermediate structure containing both linkers in the framework was also designed. In this structure, the preferential CO₂ adsorption site is the tetrahedral pore in the "UiO-66-like" structure. The extra energy stabilization stems from a hydrogen bond interaction between CO₂ and a hydroxyl group on the inorganic cluster.

SUBMITTER: Venturi DM

PROVIDER: S-EPMC9478941 | biostudies-literature | 2022 Sep

REPOSITORIES: biostudies-literature

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Increased CO2 Affinity and Adsorption Selectivity in MOF-801 Fluorinated Analogues.

Venturi Diletta Morelli DM Notari Maria Sole MS Bondi Roberto R Mosconi Edoardo E Kaiser Waldemar W Mercuri Giorgio G Giambastiani Giuliano G Rossin Andrea A Taddei Marco M Costantino Ferdinando F

ACS applied materials & interfaces 20220830 36

The novel ZrIV-based perfluorinated metal-organic framework (PF-MOF) [Zr6O4(OH)4(TFS)6] (ZrTFS) was prepared under solvent-free conditions using the commercially available tetrafluorosuccinic acid (H2TFS) as a bridging ditopic linker. Since H2TFS can be seen as the fully aliphatic and perfluorinated C4 analogue of fumaric acid, ZrTFS was found to ...[more]

PMID: 36039930

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Project description:A magnesium-based metal-organic framework (Mg-MOF-74) exhibits excellent CO2 adsorption under ambient conditions. However, the photostability of Mg-MOF-74 for CO2 adsorption is poor. In this study, Mg x Cu1-x -MOF-74 was synthesized by using a facile "one-pot" method. Furthermore, the effects of synthesis conditions on the CO2 adsorption capacity were investigated comprehensively. X-ray diffraction, Fourier transform infrared, scanning electron microscopy, thermo gravimetric analysis, inductively coupled plasma atomic emission spectroscopy, ultraviolet-visible spectroscopy and photoluminescence spectroscopy, and CO2 static adsorption-desorption techniques were used to characterize the structures, morphology, and physicochemical properties of Mg x Cu1-x -MOF-74. CO2 uptake of Mg x Cu1-x -MOF-74 under visible light illumination was measured by the CO2 static adsorption test combined with the Xe lamp. The results revealed that Mg x Cu1-x -MOF-74 exhibited excellent photocatalytic activity. Furthermore, the CO2 adsorption capacity of Mg x Cu1-x -MOF-74 was excellent at a synthesis temperature and time of 398 K and 24 h in dimethylformamide (DMF)-EtOH-MeOH mixing solvents, respectively. Mg x Cu1-x -MOF-74 retained a crystal structure similar to that of the corresponding monometallic MOF-74, and its CO2 uptake under visible light was superior to that of the corresponding monometallic MOF-74. Particularly, the CO2 uptake of Mg0.4Cu0.6-MOF-74 under Xe lamp illumination for 24 h was the highest, up to 3.52 mmol·g-1, which was 1.18 and 2.09 times higher than that of Mg- and Cu-MOF-74, respectively. The yield of the photocatalytic reduction of CO2 to CO was 49.44 μmol·gcat -1 over Mg0.4Cu0.6-MOF-74 under visible light for 8 h. Mg2+ and Cu2+ functioned as open alkali metal that could adsorb and activate CO2. The synergistic effect between Mg and Cu metal strengthened Mg x Cu1-x -MOF-74 photostability for CO2 adsorption and broadened the scope of its photocatalytic application. The "bimetallic" strategy exhibits considerable potential for use in MOF-based semiconductor composites and provides a feasible method for catalyst design with remarkable CO2 adsorption capacity and photocatalytic activity.

Dataset Information

Increased CO₂ Affinity and Adsorption Selectivity in MOF-801 Fluorinated Analogues.

Publications

Increased CO<sub>2</sub> Affinity and Adsorption Selectivity in MOF-801 Fluorinated Analogues.

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