Lack of breathable oxygen in space is due to its high binding energy
DOI: 10.1063/PT.5.028854
Science : Although oxygen is the third most common element in the universe, there’s almost no molecular oxygen (O2) in space. In fact, astronomers have found it in just two other places besides Earth: the Orion Nebula and the Rho Ophiuchi cloud. To figure out why, Jiao He of Syracuse University and his colleagues measured the energy required to desorb atomic oxygen from an interstellar dust grain surface and found it to be twice the value previously calculated. Because of their high binding energy, oxygen atoms tend to stick to stardust particles rather than join together. Oxygen’s high binding energy also means that oxygen atoms stuck to dust are more likely to combine with hydrogen atoms and create water ice, which is considered to be one of the raw materials necessary for life.