Room Temperature Flexible Ammonia Sensor Based on Sb-Doped SnO2/Polypyrrole Nanohybrid

In this study, Sb-doped SnO2 nanosphere composite polypyrrole nanohybrid with different doping ratios (0-5 mol%, Sb:Sn) and composite ratios (0-30 mol%, Sb-doped SnO2:polypyrrole) is synthesized by hydrothermal method and in situ chemical oxidation method. The flexible sensors are fabricated by drop-casting the materials on polyamide substrate and gas sensing performances are investigated systematically at room temperature. The results show that the 3 at% Sb-doped 20 mol% SnO2/polypyrrole nanohybrid exhibits excellent sensitivity (approximate to 213% toward 100 ppm NH3) at room temperature, which are about 3 times as much as those of polypyrrole, as well as excellent selectivity and humidity resistance, reliable repeatability, and good robustness. The enhance sensing performance can be attributed to the formation of p-n junction between conducting polymers and metal oxide semiconductor materials and the doping of Sb elements allows more electrons to transfer to polypyrrole, which further thickens the depletion layer and decreases hole concentrations in air. Therefore, Sb-doped SnO2/polypyrrole nanohybrid may be a promising sensitive material for the design and manufacture of room temperature flexible ammonia gas sensors.