Adsorption and diffusion behaviors of H2, H2S, NH3, CO and H2O gases molecules on MoO3 monolayer: A DFT study

Molybdenum trioxide (MoO3) with α-phase is a promising material for gas sensing because of its high sensitivity, fast response and thermodynamic stability. To probe the mechanism of superior gas detection ability of MoO3 monolayer, the adsorption and diffusion of H2, H2S, NH3, CO and H2O molecules on two-dimensional (2D) MoO3 layer are studied via density functional theory (DFT) calculations. Based on calculated adsorption energies, density of states, charge transfer, diffusion barriers and diffusion coefficient, MoO3 shows a superior sensitive and fast response to H2 and H2S than CO, NH3, H2O, which is consistent with experimental conclusions. Moreover, the response of MoO3 to H2S and H2 will be obviously enhanced at high gas concentration, and the incorporation of H2 and H2S results in an obvious increasing in DOS near Fermi level. Our analysis provides a conceptual foundation for future design of MoO3-based gas sensing materials.