Detection of NO, NO2, H2S, and SO2 by SnSe2 gas sensor at room temperature: DFT simulation and experimental validation

To investigate the room-temperature gas sensing performance of two-dimensional SnSe₂ toward various toxic and hazardous gases, the adsorption energies and electronic density of states (DOS) of SnSe₂ upon interaction with four typical gases (NO, NO₂, H₂S, and SO₂) were calculated based on density functional theory (DFT). SnSe₂ gas sensors were fabricated via mechanical exfoliation and an all-dry transfer process, and their sensing properties were experimentally validated at room temperature. The results indicate that for the oxidizing gases NO and NO₂, the adsorption energies on SnSe₂ were -4.22 eV and -1.01 eV, respectively, corresponding to sensor responses of 5.1% and 7.5%, with response times of 678 s and 375 s. For the reducing gases H₂S and SO₂, the adsorption energies were -0.31 eV and -0.27 eV, respectively, yielding responses of 15% and 6% with response times of 367 s and 549 s. Notably, the sensor demonstrated satisfactory repeatability and 30-day stability for H₂S detection, exhibiting a 1% response to 1 ppm H₂S at 25 °C and 50% relative humidity (RH), along with an excellent linearity (R² = 0.97) within the concentration range of 1 to 12.5 ppm. The experimental and theoretical results collectively validate the great potential of SnSe₂ for gas sensing and highlight its unique room-temperature response behaviors to various gases.