Density Functional Theory Study of Two-Dimensional SnS₂ Doping for Detection of Hydrogen Sulfide

The efficient and rapid detection of toxic and combustible H2S released during industrial processes is extremely crucial. However, two-dimensional (2D) SnS2 shows a weak interaction with H2S, leading to difficult detection. In this work, we use density functional theory (DFT) calculations to modify the SnS2 monolayer by N, P, Ge, and Se doping and investigate the adsorption properties and gas-sensing mechanism of each doped SnS2. By analyzing the adsorption energy, charge density difference, band structure, and recovery time, we suggest that Ge and Se doping is detrimental to the detection of H2S. Significantly, N and P doping can efficiently strengthen the interaction between SnS2 and H2S and simultaneously maintain the physisorption with the adsorption energy of −0.60 eV and −0.64 eV, leading to a suitable recovery time (5.64 × 10–2 s and 1.20 × 10–2 s). The H2S@N and P-SnS2 systems exhibit significant band gap decreases (1.51 and 0.84 eV). Moreover, combined with nonequilibrium Green’s function (NEGF) method, the simulation of current–voltage characteristics further reveals their high sensitivity, reaching nearly 100%. Hence, the DFT and NEGF calculations in this work provide an efficient doping strategy to make 2D SnS2 a highly reusable and sensitive gas sensor for the detection of H2S.