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

The adsorptions of toxic gases SO₂ and H₂S on 2D α/β/γ-FeB₆ monolayer were investigated using density functional theory calculations. To analyze the interaction between gas molecule H₂S/SO₂ and α/β/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/β-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/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.

Calculations were performed at GGA-PBE/DNP level using the Dmol³ module implemented in the Material Studio 2018 software package.