Oxidation stability of borophene is deemed as a prerequisite for its broad applications, however there is a contradiction from experiments whether boron atoms in borophenes are ac-tive or inert to oxidation. Our detailed den-sity functional theory calculations performed herein indicate that O2 molecules tend to be chemisorbed on supported β12 borophene easily and dissociate into separated atoms by over-coming very low barriers, and spin triplet-to-singlet conversion is not important in the chemisorption process. It is found that O2molecules prefer to be adsorbed on two hexa-coordinated boron atoms, then dissociate and di-use along -lled-hexagon ribbons. A compar-ison between our calculated core-level binding energies and the experimental X-ray photoelectron spectroscopy, in combination with detailed kinetic analyses, indicates that boron atoms in supported borophenes are active rather than inert to oxidation. This conclusion is further supported by a novel B5O4 sheet model cal-culation. The results on the oxidation stability and mechanism suggest the protection of borophenes from oxygen is therefore essential for their broad applications.
