When a material combines with oxygen, the process is known as oxidation. It can be a slow process such as iron rusting, or a flamboyant process such as fire. Usually the end state is more stable than the original composition and it is difficult if not impossible to reverse.
The catalytic converters on automobiles add an oxygen molecule to carbon monoxide to make it non-toxic. However that reaction requires very high temperatures and an expensive metal - platinum.
ORNL-grown oxygen ‘sponge’ presents path to better catalysts, energy materials explains the new oxygen sponge is strontium cobaltite, which is known to occur in a preferred crystalline form called brownmillerite. With some clever insight, they processed this into a more desirable form called perovskite.
The new material is interesting - it has two phases, one with the extra oxygen and the other without. In one phase it is an insulator. In the other phase, it responds to magnetic fields. This material should have multiple applications in batteries, gas conversion, fuel cells, etc.