Synthesis of wrinkled and porous ZnO–SnO2 hollow nanofibers and their gas sensing properties

• Wrinkled and porous ZnO–SnO2 hollow nanofibers were successfully fabricated.
• The rough and porous nanofibers are composed of particles with sizes around 5–20 nm.
• The wall thickness of the hollow nanofibers is about 20 nm.
• The composite hollow nanofibers are polycrystalline in structure.
• The sensor exhibits highly improved ethanol sensing properties at 260 °C.

Wrinkled and porous ZnO–SnO2 hollow nanofibers with an average diameter of ~150 nm were synthesized by a electrospinning method. The crystal structure, chemical composition and morphology of the nanofibers were characterized. The results showed that the hollow nanofibers were composed of nanoparticles with sizes around 5–20 nm and the wall thickness is about 20 nm. A sensor based on these nanofibers exhibits highly improved ethanol sensing properties at the optimum temperature of 260 °C. The response values are about 83, 168.3, 702.5 and 1260.6 for 20, 200, 1000 and 2000 ppm ethanol, respectively. The response and recovery time are in the range of 4–7 s and 4–5 s, respectively. Furthermore, this sensor has excellent stability and good selectivity for ethanol. All these prominent sensing properties can be attributed to the unique structure of wrinkled and porous hollow nanofibers and the promoting effect of the heterojunction structure. The gas sensing mechanism is also discussed.