They draw moisture from desert air and remove greenhouse gases that drive climate change. It may sound like something Bong-i Kim Seon-dal would say, but scientists are making it real. It's thanks to materials riddled with countless tiny pores. The surface area that gases pass through has increased dramatically, boosting the efficiency of chemical reactions. They also remove pharmaceuticals or toxic substances that have leaked into soil or air.
The Royal Swedish Academy of Sciences Nobel Committee said on the 8th (local time) that Susumu Kitagawa (74), a professor at Kyoto University in Japan; Richard Robson (88), a professor at the University of Melbourne in Australia; and Omar M. Yaghi (60), a professor at the University of California, Berkeley (UC Berkeley) in the United States, were selected as this year's Nobel Prize in chemistry laureates for creating a new molecular structure called metal-organic frameworks (MOFs) that "dramatically increase the space through which chemicals can flow."
◇ Dramatically expanding the surface area for chemical reactions
MOFs can be described as a kind of metal sponge. They are crystalline structures made by linking metal ions with organic molecules, with innumerable tiny pores inside that allow other molecules to pass in and out. Using MOFs, several technologies have been developed, including harvesting moisture from parched desert air to produce water and capturing carbon dioxide in the air to address the climate crisis.
Heiner Linke, Chairperson of the Nobel Committee for Chemistry, said, "Metal-organic frameworks have enormous potential," and explained that they "have opened up previously unforeseen opportunities to create tailor-made materials with new functions."
The Nobel Committee said that in 1989 Robson created an MOF structure centered on copper cations that resembled a diamond crystal but with a great many empty spaces within. The structure was unstable, however, with the drawback that it collapsed easily.
Kitagawa later demonstrated that gases can move freely in and out of an MOF structure and that it is possible to make MOFs flexible. Yaghi succeeded in making robust and stable MOFs.
The Nobel Committee said, "Chemists around the world have created tens of thousands of MOFs, some of which are used to solve major human challenges such as carbon capture, water scarcity, and environmental remediation."
◇ Succeeding at absorbing water in the Arizona desert
Drawing water from desert air is now a reality. In 2018, Yaghi of UC Berkeley, together with Evelyn Wang of the Massachusetts Institute of Technology (MIT), succeeded in using MOFs to produce drinking water in the Arizona desert, where the average relative humidity is below 20%. Korean researchers Kim Hyeon-ho and Yang Seong-u of MIT also took part in the study.
The test site was a desert area near Scottsdale, Arizona. Humidity there reaches 40% at night and drops to 8% during the day, making it one of the driest regions in the United States.
When air passes through an MOF made of the metal zirconium, moisture is adsorbed. MOFs are densely packed with countless channels and pores inside, giving them an enormous surface area. A sugar-cube-sized MOF has a surface area six times the size of a soccer field.
Thanks to this structure, they can absorb large amounts of gas or liquid like a sponge. When MOFs heat up in sunlight during the day, they release water vapor. The vapor turns directly into water through a condenser at the bottom of the device.
MOFs can also be applied to gas purification and drug storage and delivery. They can separate PFAS (per- and polyfluoroalkyl substances) from water and break down trace pharmaceuticals released into the environment. In the United States, technologies are being developed that use MOFs to remove chemical weapons such as sarin gas, which damages the central nervous system.
Meanwhile, Japan produced a Nobel laureate in chemistry this year following the Nobel Prize in physiology or medicine. The Nobel Prize in physiology or medicine announced on the 6th included Sakaguchi Shimon, a distinguished professor at Osaka University in Japan.
The Nobel Committee has announced the laureates for the science prizes, including physiology or medicine, physics, and chemistry. It will announce the literature prize on the 9th, the peace prize on the 10th, and the economics prize on the 13th.
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