Ag quantum dots modified SnS2 nanocomposites for high-performance formamide detection at room temperature: Catalytic enhancement and electronic structure tuning

Formamide (CH 3 NO) presents significant health hazards due to its prolonged volatilization like formaldehyde, making rapid and accurate detection critical. However, studies on formamide sensors remain limited. Hence, a high-performance formamide sensor was achieved using Ag quantum dots (QDs) modified SnS 2 nanosheets, operating efficiently at room temperature of 25 °C. The microstructure and material properties of the nanocomposites were fully characterized, showing that ∼4.5 nm of Ag QDs were uniformly dispersed on the SnS 2 nanosheets with a thickness of ∼14 nm. The optimal Ag QDs-SnS 2 nanocomposites sensor demonstrated remarkable improvement over pure SnS 2 , including a high response of 13.3–100 ppm formamide, along with good selectivity, repeatability, and long-term stability. Density functional theory (DFT) was utilized to reveal the catalyst effect of Ag QDs at the atomic level and adsorption behaviors of CH 3 NO molecule on sensing material. The enhanced sensing mechanism was attributed to the extraordinary catalyst activities of Ag QDs, and modulation of electronic structures of nanocomposites, as well as the spillover effect. This work provides a novel insight into the formamide sensing mechanism, paving the way for the future design of high-performance formamide sensors.