Synergistic enhanced NH3-sensing of SnS via Ti3C2Tx-oriented vertical growth and oxygen-containing functional group regulation

Abstract

Stannous sulfide (SnS) is a promising candidate for gas sensing applications due to its unique two-dimensional (2D) puckered monolayer and response capability at room temperature (25 °C). However, the general stacking of 2D nanoflakes as well as the characteristic of poor conductivity of SnS suppresses its response capability towards rarefied gas detection. Here, we report a nanocomposite of SnS/Ti₃C₂T_x, featured by the vertically aligned, discrete SnS nanoflakes grown on the surface of Ti₃C₂T_x. The SnS/Ti₃C₂T_x nanocomposite with unique loose architecture and modulated conductivity was achieved via a one-step solvothermal process with Ti₃C₂T_x induction. Further boosting of the sensitivity towards trace NH₃ was realized by functionalizing the surface of SnS with precise alkaline treatment. The oxygen-containing functional groups on the surface of SnS, introduced during alkaline treatment, serve as catalytic medium to activate S atoms for NH₃ adsorption enhancement, which was clarified by first-principles calculations. The obtained nanocomposite achieved a significant promotion of response by 27.5 times that of pure SnS towards 5 ppm NH₃ at 25 °C. It also exhibits a practical capability to sense rarefied NH₃ as low as 250 ppb with a response of 0.453. The accomplishments light a new way for the research of microstructure construction and ultra-low concentration gas detection of black phosphorus-like materials.