We do fine with the 21 per cent oxygen in the air around us. But sometimes we need oxygen in higher concentrations; for example lung patients must carry heavy oxygen tanks, cars using fuel cells need a regulated oxygen supply. Perhaps one day in the future even sunlight-driven “reversible” fuel cells will be made. With these we will have to separate oxygen from hydrogen in order to recombine them in order to get energy.
"In the lab, we saw how this material took up oxygen from the air around us," says Christine McKenzie.
The new material is crystalline, and using x-ray diffraction the researchers have studied the arrangement of atoms inside the material when it was filled with oxygen, and when it was emptied of oxygen.
Oxygen comes and goes in many places
The fact that a substance can react with oxygen is not surprising. Lots of substances do this — and the result is not always desirable: Food can go rancid when exposed to oxygen. On the other hand a wine’s taste and aroma is changed subtly when we aerate it — but not with too much oxygen! Our bodies cannot function if we do not breathe.
"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. 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," says Christine McKenzie.
The material is so effective at binding oxygen, that only a spoon of it is enough to suck up all the oxygen in a room. The researchers’ work indicates that the substance can absorb and bind oxygen in a concentration 160 times larger than the concentration in the air around us.
"It is also interesting that the material can absorb and release oxygen many times without losing the ability. It is like dipping a sponge in water, squeezing the water out of it and repeating the process over and over again," Christine McKenzie explains.
Once the oxygen has been absorbed you can keep it stored in the material until you want to release it. The oxygen can be released by gently heating the material or subjecting it to low oxygen pressures.