Noble metal-anchored Janus Ga2SSe monolayers for toxic gas sensing: first-principles investigation.

Industrial production processes discharge substantial quantities of hazardous gases, posing severe risks to both environmental safety and human well-being. Therefore, developing high-performance gas sensors that enable accurate detection of these dangerous species is urgently needed. Using density functional theory (DFT) calculations, this study explores the adsorption and gas-sensing performance of Ir-, Pt-, and Au-doped Ga2SSe monolayers toward six toxic gases (NO, NO2, SO2, CO, H2S, and NH3). It is found that Ir-Ga2SSe, Pt-Ga2SSe, and Au-Ga2SSe all exhibit excellent structural stability, and the dopant atoms significantly enhance the capture capability of Ga2SSe toward the target gases. Specifically, Ir-Ga2SSe and Pt-Ga2SSe exhibit strong chemisorption toward all six gases, while Au-Ga2SSe displays strong adsorption toward NO, NO2, and SO2 molecules. These findings are further confirmed by electronic structure analyses, including charge density difference (CDD) and partial density of states (PDOS). Moreover, a comprehensive analysis of band gap variation and sensing responses reveals that Ir-Ga2SSe possesses outstanding sensitivity toward all six target gases, whereas Pt-Ga2SSe and Au-Ga2SSe show excellent response characteristics toward NO, NO2, H2S, and NH3. Finally, the recovery time calculations indicate that the Au-Ga2SSe monolayer is well suited for sensing NO, SO2, and NH3 at ambient temperature, whereas Pt-Ga2SSe is reusable for detecting all six toxic gases under elevated temperatures. Therefore, this study serves as a basis for designing novel gas sensors aimed at detecting industrial toxic gases.