High toluene sensing properties of NiO–SnO2 composite nanofiber sensors operating at 330 °C

NiO–SnO2 composite nanofibers are synthesized by electrospinning of a poly(vinyl pyrroridone) (PVP)/SnCl2·2H2O/NiCl2 solution. Indirect-heated sensors are fabricated by coating the nanofibers on ceramic tubes with signal electrodes. The obtained nanofibers are analyzed by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The sensors are tested at different temperatures to various gases. High toluene sensing properties are observed at 330 °C, and the corresponding response value (Ra/Rg), response time, and recovery time are about 11.2 s, and 4 s to 50 ppm toluene at this condition. Good selectivity and excellent stability are also observed based on the sensors at this temperature. These high sensor performances are explained by the sensing enhancement brought about by NiO addition and the one-dimensional nanostructure of nanofibers.