Humans need oxygen to breathe, but sometimes require concentrations higher than the 21% that is typically found in the air. Supplementary oxygen has typically been associated with heavy, cumbersome oxygen tanks, but a new crystalline material might change that.
Christine McKenzie of the University of Southern Denmark led a team that developed the material that is able to absorb and store oxygen at levels 160 times greater than air. The paper was published in the journal Chemical Science.
About ten liters (2.6 gallons) of the material is able to suck all of the oxygen out of a room. It binds the oxygen until environmental conditions, such as heat or low pressure, allow it to release the oxygen again. This is similar to how hemoglobin works in the blood stream; oxygen is picked up from the lungs and deposited where it is needed. The researchers are able to coax the oxygen out on demand in this fashion, though environmental conditions also affect how much it is able to absorb.
"An important aspect of this new material is that it does not react irreversibly with oxygen - even though it absorbs oxygen in a so-called selective chemisorptive process," McKenzie said in a press release. "The material is both a sensor, and a container for oxygen - we can use it to bind, store and transport oxygen - like a solid artificial hemoglobin."
Just like hemoglobin requires iron to function, this material also needs a metal to bind oxygen. The team used cobalt arranged in a very specific manner to create a molecule that can trap the oxygen gas.
"Cobalt gives the new material precisely the molecular and electronic structure that enables it to absorb oxygen from its surroundings," McKenzie explained. "This mechanism is well-known from all breathing creatures on earth: Humans and many other species use iron, while other animals, like crabs and spiders, use copper. Small amounts of metals are essential for the absorption of oxygen, so actually it is not entirely surprising to see this effect in our new material."
There are a variety of implications for this research. It could be used to help artificial photosynthesis or to help create new types of fuel cells. The biggest and most obvious use would be to provide oxygen for divers or those who need oxygen for medical reasons, reducing the burden of traditional tanks.
"This could be valuable for lung patients who today must carry heavy oxygen tanks with them. But also divers may one day be able to leave the oxygen tanks at home and instead get oxygen from this material as it "filters" and concentrates oxygen from surrounding air or water," she said. "A few grains contain enough oxygen for one breath, and as the material can absorb oxygen from the water around the diver and supply the diver with it. The diver will not need to bring more than these few grains."
