First-principles study on α/β/γ-FeB monolayers as potential gas sensor for HS and SO.

Context: The adsorptions of toxic gases SO and HS on 2D α/β/γ-FeB monolayer were investigated using density functional theory calculations. To analyze the interaction between gas molecule HS/SO and α/β/γ-FeB monolayer, we calculated adsorption energy, adsorption distance, Mullikan charge, charge density difference, band structure, the density of states, work function, and theoretical recovery time. The adsorption energies show that HS/SO is chemisorbed on α/β-FeB while HS/SO is physiosorbed on γ-FeB monolayer. As a result, γ-FeB has a short recovery time for HS (5.71×10 s)/SO (1.94×10 s) due to modest adsorption. Therefore, γ-FeB6 may be a promising candidate for reusable H2S/SO2 sensors at room temperature. Although H2S is chemisorbed on α/β-FeB6, as the working temperature rises to 500 K, the recovery time of α/β-FeB6 for H2S can decrease to 1.13×10-1 s and 2.08×10-1 s, respectively, which are well within the detectable range. So, α/β-FeB6 monolayer also may be a good candidate for H2S gas sensor.

Methods: Calculations were performed at GGA-PBE/DNP level using the Dmol module implemented in the Material Studio 2018 software package.