Theoretical Investigation of TiSiO4 Monolayer Membranes for Highly Selective H2S Detection from Hazardous Gas Mixtures

H2S is a common industrial and environmental pollutant with colorless, flammable, and toxic properties that affects human health from a wide range of sources. The three-dimensional TiSiO4 monolayer membrane shows excellent sensing performance toward H2S gas; however, the nanoscale sensing mechanism between H2S and the TiSiO4 membrane is still not clear. In this work, the sensing performance of the TiSiO4 monolayer membrane toward H2S, CO, H2, CH4, SO2, and H2O gases mixture is studied by first-principles calculations. The adsorption of H2S exhibits the lowest energy of adsorption together with the largest band gap change and charge transfer, which indicates a stronger adsorption effect of H2S gas over the other gases and is consistent with experimental conclusions. The response time of H2S on the TiSiO4 monolayer is significantly smaller than that of the TiO2 nanotube membrane, and the density of state of the TiSiO4 system increases obviously near the Fermi level after adsorption of H2S, suggesting strong chemical adsorption and significant changes in conductivity of the system. Moreover, H2S gas shows a significant impact on the transmission spectrum and conductance, and the largest diffusion coefficient of H2S demonstrates that the diffusion of H2S gas in the TiSiO4 monolayer is much faster than those of other gases.