First-principles study of NO2 adsorption on noble metals doped SnS2/SnSe2 heterostructure

The adsorption behaviors of NO₂ gas molecule on pristine and noble metal (NM) atoms (Pd, Ag, Pt and Au) doped SnS₂/SnSe₂ heterostructure have been studied using the first-principles calculations based on density-functional theory (DFT-D2 method). Pristine SnS₂/SnSe₂ heterostructure exhibits small adsorption energy and low charge transfer, while the NM-doped heterostructures showed chemisorption towards NO₂ gas molecules. The introduction of NM can also enhance the interaction between the NO₂ and substrates. The significant changes in work function (WF) after NO₂ adsorption indicate that Ag-doped and Au-doped SnS₂/SnSe₂ heterostructure are more sensitive to NO₂. In addition, applying electric field and strain can also improve the adsorption behavior of NO₂ in the Ag-doped SnS₂/SnSe₂ heterostructure. Therefore, these results not only provide a fundamental understanding of NM-doped SnS₂/SnSe₂ heterostructure as promising gas sensing materials for NO₂ detection, but also provide theoretical guidance for designing high performance gas sensors based on SnS₂/SnSe₂ heterostructure.