First-Principles Study on the Oxidation of Supported β12-Borophene

The oxidation stability of borophene is deemed as a prerequisite for its broad applications; however, there is a contradiction from experiments as to whether boron atoms in borophenes are active or inert to oxidation. Our detailed density functional theory calculations performed herein indicate that O-2 molecules tend to be chemisorbed on supported beta(12)-borophene easily and dissociate into separated atoms by overcoming very low barriers, and spin triplet-to-singlet conversion is not important in the chemisorption process. It is found that O-2 molecules prefer to be adsorbed on two hexacoordinated boron atoms and then dissociate and diffuse along filled-hexagon ribbons. A comparison 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 calculation. The results on the oxidation stability and mechanism suggest the protection of borophenes from oxygen is therefore essential for their broad applications.