First principles study of transition metal (TM = Sc, Ti, V, Cr, Mn) doped penta-BAs5 monolayer for adsorption of CO, NH3, NO, SO2

In this paper, the adsorption capacity of intrinsic penta-BAs₅ monolayer on CO, NH₃, NO, SO₂ and the effect of transition metal doping on gas sensing characteristics are systematically studied by first-principles calculations. Adsorption energy, recovery time, band structure, charge transfer and density of states (DOS) are investigated. The electronic properties and sensing mechanisms under different adsorption systems are expounded. The results showed that the intrinsic penta-BAs₅ monolayer had the strongest adsorption capacity for NO and weak sensitivity to CO, NH₃ and SO₂, which shown strong gas selectivity. Moreover, the recovery time of NO at 380 k was 3.93 s, which was more inclined to be desorption at high temperature. In addition, Sc and Ti doping could selectively improve the adsorption capacity of the intrinsic penta-BAs₅ monolayer. The charge transfer of SO₂-Sc-BAs₅ and CO-Ti-BAs₅ were increased by 6.78 and 10.33 times compared with those before doping. The band structure and DOS show that Ti atom and CO have orbital hybridization, which improved the interaction between gases and penta-BAs₅. Therefore, intrinsic penta-BAs₅, Sc-BAs₅ and Ti-BAs₅ are suitable for gas sensing and toxic gas monitoring, and have broad application prospects.