Pressure-induced band engineering, work function and optical properties of surface F-functionalized Sc2C MXene

Functionalized MXenes exhibit versatile potential applications in supercapacitors, hydrogen storage and sensor materials. In this paper, we have systematically explored the pressure-induced band modulation, work function and optical properties of a Sc2CF2 monolayer using first-principles calculations. The electronic structure reveals that the Sc2CF2 monolayer is a semiconductor under zero pressure with a band gap of 1.023 eV. The band gap decreases gradually with increasing pressure and undergoes a semiconductor-metal transition at 9 GPa. A strong hybridization exists between the Sc-d and C-p states, which was further confirmed by analysis of the crystal orbital Hamilton population (COHP), bond order and atomic charge. The left shift of the Sc-d state conduction band minimum (CBM) and right shift of the Sc-d and C-p valence band minimum (VBM) with increasing pressure result in a decrease in the band gap and metallization of Sc2CF2 at similar to 9 GPa. The work function can be effectively controlled by pressure, and increases from 4.803 to 5.079 eV with increasing pressure. In addition, the optical properties under pressure were explored.