Exploring adsorption and sensing mechanism of Li-decorated N-doped black phosphorene for toxic gases: Insights from first-principles calculations

Abstract

The two-dimensional material black phosphorene has attracted extensive attention due to its unique sensing performance. Herein, on the basis of first-principles calculations, we investigate the adsorption and dissociation of several toxic gases (NO2, SO2, H2S) on the Li-decorated N-doped black phosphorene (LNBP). The effect of gas molecule coverage on the electronic and sensing properties of LNBP is also studied. Our results demonstrate that NO2 and SO2 have a strong interaction with LNBP due to the hybridization of O-2p with P-3p orbitals, while the 3NO2-LNBP system exhibits a high charge transfer up to 0.95 e from the Li atom to gas molecules. Furthermore, the capture ability of toxic gas on the LNBP follows the sequence of H2S < SO2 < NO2, which corresponds with their adsorption energy of -0.68 eV, -1.37 eV and -2.55 eV. In addition, the LNBP is appropriate for NO2 gas detection with a high sensitivity ranging from 84.8 % to 92.6 % as the coverage increases. The significant changes in the work function of NO2 and SO2 suggest a high selectivity in LNBP. The energy barrier of dissociation is relatively low at 1.24 eV with an exothermic process for the NO2-LNBP system. We believe that these findings provide an important insight into sensing applications of metal-decorated black phosphorene.