Highly selective ammonia detection by SnS₂ nanosheets functionalized Ti₃C₂T_x

SnS₂ is very promising for next-generation gas sensors due to the abundant edge-exposed sites, large surface-to-volume ratio, and high charge carrier mobility. However, SnS₂ suffers from low response and poor selectivity in gas sensing. In this paper, the self-activated SnS₂ gas sensor functionalized with Ti₃C₂T_x is designed and fabricated to monitor NH₃ at room temperature (RT) in daily life. The response of SnS₂ and Ti₃C₂T_x composites to 500 ppm NH₃ is about 86.35 % at RT, which is enhanced by 43.82 % and 38.33 % in comparison with pure SnS₂ and Ti₃C₂T_x, respectively. The SnS₂-functionalized Ti₃C₂T_x micropatterns show high selectivity to NH₃ and a low detection limit of 143 ppt. Density-functional theory (DFT) calculations reveal that the SnS₂/Ti₃C₂T_x heterojunction provide the additional active sites for NH₃ adsorption, enhancing the absorption and diffusion capabilities of NH₃. In addition, the remarkable metallic conductivity of Ti₃C₂T_x MXene ensures efficient electron transfer to improve the sensing characteristics. © 2025 Elsevier B.V.