Sensitive ethanol sensors fabricated from p-type La0.7Sr0.3FeO3 nanoparticles and n-type SnO2 nanofibers

La0.7Sr0.3FeO3 nanoparticles are prepared by a citrate method, and SnO2 nanofibers are synthesized via an electrospinning process. In order to improve the sensing performance, La0.7Sr0.3FeO3 nanoparticles are coated on the surface of SnO2 nanofibers. The materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS). Three sensors are fabricated from La0.7Sr0.3FeO3 coated SnO2 nanofibers with different coating times. And the sensors with only La0.7Sr0.3FeO3 nanoparticles and SnO2 nanofibers are also fabricated for comparison. The sensors are exposed to ethanol with various concentrations and operating temperatures, and sensor performances are calculated and evaluated by a sensing analysis system automatically. It is clear that the sensors based on SnO2 nanofibers with four times of La0.7Sr0.3FeO3 coating (L4SnO2 sensors) own the highest response of 28–1 ppm ethanol, which is 5 times larger than that of SnO2 nanofiber sensors and 8 times greater than that of La0.7Sr0.3FeO3 nanoparticle sensors. Moreover, fast response and recovery, good selectivity, anti-humidity, and high stability of L4SnO2 sensors are obtained herein. To understand the improved performance of L4SnO2 sensor, the sensing mechanism is discussed.