Electronic and optical properties of C-doped BN nanotubes by adsorption of typical decomposition products of C3F7CN gas

Abstract

Abstract C3F7CN((CF3)2CFCN) is a potential environmentally friendly insulating gas to alternative SF6. Finding an effective way to monitor C3F7CN gas decomposition products is necessary to ensure the stable operation of power equipment. The adsorption behaviors of typical decomposition products (CF4 and CF3CN) on pristine boron nitride nanotubes(BNNT) and C-doped boron nitride nanotubes(C-BNNT) were investigated. The adsorption energy of CF4 and CF3CN on pristine BNNT is small, and the interaction distance between molecules is large, which indicates that pristine BNNT and gas molecules form physical adsorption through weak van der Waals forces. Then, we studied the adsorption behaviors between C-doped BNNT and gas molecules. The adsorption of CF4 on C-doped BNNT has a few effect on the band gap of CB-BNNT. For CF3CN molecules, the adsorption of F atoms on the C-doped BNNT is physical adsorption, while the N atom in the -CN group forms chemical adsorption at the CN and CB sites, with higher charge transfer amount. After adsorption -CN group, and the 2p orbital of N atom and the 2p orbital of doped C atom dominate at the Fermi level, which changes band gap of C-doped BNNT. Meanwhile, adsorption behaviors weaken the absorption capacity of C-BNNT for infrared light and reduce its reflectivity to ultraviolet light. Tube diameter has a significant effect on the adsorption of N atom of CF3CN on C-BNNTs, the band gap and optical properties changes with the diameter increases. These changes of electronic and optical properties indicated that C-doped BNNT can be used as a potential material for detecting CF3CN.