Optimization NH3 sensing performance manifested by gas sensor based on Pr-SnS2/ZnS hierarchical nanoflowers

Pure and Pr doped 3D SnS₂/ZnS hierarchical nanoflowers were prepared by two-step hydrothermal method. The as-prepared samples were characterized by various techniques. For the Pr-SnS₂/ZnS samples, XPS results confirmed that Pr³⁺/Pr⁴⁺ ions were successfully doped into the samples. Pr doping led to lattice distortion, inhibiting grain growth and reducing grain size. Compared with sensors based on SnS₂/ZnS nanoflowers, Pr doped SnS₂/ZnS samples exhibited better gas sensing performance to 50 ppm ammonia gas at 160 °C, including higher response (14.03) and ultrafast responding and recovering time (6 s/13 s). The excellent gas sensing performance may be attributed to more free electrons generated by Pr doping, SnS₂/ZnS heterojunction and the high specific surface area of such unique hierarchical flower-like structure. In addition, the gas sensing mechanism of Pr-SnS₂/ZnS sensor was also analyzed.