Scientists at U.S. Department of Energy's Argonne National laboratory are putting the pressure on metal-organic frameworks (MOF).
In MOF materials, metal ions can be connected by organic molecules to form scaffolding-like structures similar to a molecular Tinker toy. The struts that make up the framework structure do not fill space efficiently, in the way that Lego blocks might, leaving extra spaces in the structure which are capable of containing guest molecules.
Behaving as molecular-scale sponges these MOFs have wide ranging potential uses for filtering, capturing or detecting molecules such as carbon dioxide or hydrogen storage for fuel cells.
"By examining the framework at various pressures," scientist Karena Chapman said. "We found that the MOF compresses rapidly at high pressures."
Since the MOF frameworks do not fill space efficiently, the structures are particularly sensitive to even relatively moderate applied pressures. For any carbon dioxide or hydrogen gas storage applications, the MOF materials (which are generally formed as fine particles or small crystals) will need to be compressed into pellets to optimize the volume capacity (an important target parameter). This would subject the structure to pressures up to several gigapascals (GPa).
While a few GPa of pressure would have minimal impact on denser oxide-based materials, MOFs may show significant and possibly irreversible distortions to the structure and to the selective gas storage properties. Understanding how MOF materials can behave under pressure is an important step in taking MOF technology beyond the lab.
Chapman, along with Argonne scientists Gregory Halder and Peter Chupas, synthesized a Copper-Benzenetricarboxylate MOF and subjected the framework to various pressures inside a diamond anvil cell with and without pressure-transmitting fluids at the laboratory's Advanced Photon Source.
X-ray diffraction from the laboratory's Advanced Photon Source data showed a transition from the hard regime where pressure transmitting fluid penetrates the framework cavities to a soft regime where the MOF compresses concertedly.
This uncharacteristic behavior is caused by the presence of smaller molecules in the pressure-transmitting fluid that can permeate the framework's cavities. This leads to a supersaturated state that counteracts the external pressure until a threshold pressure is reached and the MOF rapidly compresses and cannot allow any additional guest molecules into the cavities.
"MOFs have wide and varied potential applications in the real world," Chapman said. "By exploring high pressure phenomenon, we come a step closer to realizing these advanced applications."
Brock Cooper | EurekAlert!
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering