First-principles study on α/ß/γ-FeB6 monolayers as potential gas sensor for H2S and SO2.

ABSTRACT

CONTEXT The adsorptions of toxic gases SO2 and H2S on 2D α/ß/γ-FeB6 monolayer were investigated using density functional theory calculations. To analyze the interaction between gas molecule H2S/SO2 and α/ß/γ-FeB6 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 H2S/SO2 is chemisorbed on α/ß-FeB6 while H2S/SO2 is physiosorbed on γ-FeB6 monolayer. As a result, γ-FeB6 has a short recovery time for H2S (5.71×10-8 s)/SO2 (1.94×10-5 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/ß-FeB6, as the working temperature rises to 500 K, the recovery time of α/ß-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/ß-FeB6 monolayer also may be a good candidate for H2S gas sensor. METHODS: Calculations were performed at GGA-PBE/DNP level using the Dmol3 module implemented in the Material Studio 2018 software package.