Kyoto University researchers have designed a temperature-controllable copper-based material for sieving or storing different kinds of gases. The rationale used to design the material, described in the journal Science, could act as a blueprint for developing nanoporous materials with a wide variety of energy, medical and environmental applications.
The porous nanomaterials that are currently used for gas separation and storage are not tuneable: their pores are persistent and rigid. Susumu Kitagawa, Nobuhiko Hosono, and their colleagues of Kyoto University's Institute for Integrated Cell-Material Sciences (iCeMS) wanted to find a way to dynamically change pore sizes in this type of material.
They designed a porous coordination polymer that was formed of copper atoms linked by butterfly-shaped ligands made from isophthalic acid and phenothiazine-5,5-dioxide. The resultant material was comprised of tiny nanocages, each with eight protruding channels. At very low temperatures, the channels connecting the nanocages were so narrow that they were effectively closed. As the temperature was increased, the channels opened more and more, allowing gas molecules to move between the cages.
The team found that a gas could move or become locked within the material depending on the size of the gas's molecules and how wide the material's channels were at a given temperature. They also found that the material adsorbed a gas at high temperatures and held it in when ambient temperatures were applied, effectively storing the gas.
Furthermore, when the researchers applied gas mixtures to the material, they found they could separate the gases based on the temperature applied. For example, the material selectively adsorbed oxygen when a gas mixture of equal concentrations of oxygen and argon was applied for one hour at a temperature of -93°C and a pressure of one bar. The material selectively adsorbed oxygen even when the argon concentration in the mixture was significantly higher than that of the oxygen.
"The presented porous system that uses a robust framework with thermally active molecular functionality realizes temperature-regulated gas adsorption/desorption by design, in which local flexibility at the aperture plays a pivotal role," the researchers conclude.
Design and control of gas diffusion process in a nanoporous soft crystal.
Cheng Gu, Nobuhiko Hosono, Jia-Jia Zheng, Yohei Sato, Shinpei Kusaka, Shigeyoshi Sakaki, Susumu Kitagawa.
Science, 2019; 363 (6425): 387
DOI: 10.1126/science.aar6833
Kyoto University
#Polymers #Nanostructures
Researchers at Tohoku University have raised the power factor of chromium nitride thin films 250-fold by doping them with small amounts of titanium, reaching 5.26 µW cm⁻¹ K⁻². Titanium's stronger affinity for nitrogen suppresses nitrogen vacancies, cutting carrier concentration while boosting electron mobility by roughly two orders of magnitude.
Neutron diffraction at Oak Ridge National Laboratory has shown that a modest mechanical squeeze can substantially reshape the magnetic behavior of altermagnets, a class of materials under investigation for spintronics. Squeezing manganese telluride and iron sulfide crystals between titanium plates altered their magnetic domain populations and changed the anomalous Hall effect, which governs electron transport.
TlGaS2 single crystals show both in-plane and out-of-plane polarization, a rare combination in two-dimensional ferroelectrics that could widen options for ferroelectric transistors and non-volatile memory. Infrared spectroscopy revealed a soft phonon mode below 75 K, a signature tied to quantum ferroelectricity, along with weak structural changes across temperatures that lack clear heat-capacity signals, hinting at local rearrangements rather than conventional phase transitions.
This week in nanotech
$558.4M raised
5 funding rounds · 35 deals tracked
New products
Orion Sputtering Deposition SystemsAJA International Featured
Ti-WCMBN Nanomaterialia Featured
PDK (Process Design Kit)DB HiTekMarket insights
Last 30 days: Quantum Technologies drew the most money: $2.15B.
Money raised per month
Behind the deal
Who led Sandia National Laboratories’s $3.4M Grant?
See the investors with Insights Pro →
