Adsorption of gas molecules (NH3, C2H6O, C3H6O, CO, H2S) on a noble metal (Ag, Au, Pt, Pd, Ru)-doped MoSe2 monolayer: a first-principles study

Abstract

In this paper, the effects of five noble metal (Au, Pt, Pd, Ag, Ru)-doped MoSe₂ on improving the gas sensing performance were predicted through density functional theory (DFT) based on first-principles. The adsorption of NH₃, H₂S, CO, C₂H₆O and C₃H₆O gas molecules on Au-, Pt-, Pd-, Ag-, and Ru-doped MoSe₂ systems was investigated in terms of their stability, adsorption energy, charge transfer and density of states (DOS) and electronic structure. The results indicated that the noble metal atoms could be connected to the adjacent Se in the form of ionic bonds, which could be stably located on the surface of the MoSe₂ monolayer. The adsorption distance was significantly reduced, the number of electrons transferred between the metal-doped MoSe₂ substrate and the gas molecules increased, and most of the adsorption process was chemical adsorption of the noble metal-doped MoSe₂ system, which suggested that the noble-metal-doped system could remarkably enhance the gas adsorption behavior compared with the intrinsic MoSe₂ system. DOS analysis indicated that the noble metal-doped atoms had a great influence on the conductivity of the MoSe₂ monolayer. Most notably, doping the noble metals as catalysts with high activity and stability could effectively improve the gas sensing performance, laying a solid theoretical foundation for the development of high-performance two-dimensional gas sensors based on MoSe₂.