Room-temperature NH3-sensor: SnO2@PANI core-shell hollow spheres

A novel room-temperature NH3-sensing material (SnO2@PANI core-shell hollow nanospheres) was synthesized by coating various amounts of PANI on SnO2 hollow nanospheres using a simple in-situ chemical oxidation polymerization method. The morphology and nanostructures of the synthesized sensing materials were characterized using SEM, TEM, FTIR, and XRD. Gas-sensing tests demonstrate that SP-5 exhibits the highest response to NH3 at room temperature, with a response value (26.48 at 500 ppm) more than 6 times higher than that of pure PANI (4.35). This sensor displays excellent selectivity, with good anti-interference capability to CO and NO2. The improved sensing performance of the core-shell hollow structure is attributed to the unique structure and p-n heterojunction between PANI and SnO2, which is confirmed by EIS spectra.