Electrospun nanowebs of NiO/SnO₂ p-n heterojunctions for enhanced gas sensing

Highlights: • SnO₂/NiO composite nanowebs were fabricated via the electrospinning method. • The composite nanowebs sensor shows excellent sensing performance to ethanol. • The good performance attributes to the formation of p-type NiO/n-type SnO₂ heterojunctions. - Abstract: Electrospun nanowebs of p-type NiO/n-type SnO₂ heterojunctions were successfully fabricated using a simple electrospinning process followed by thermo-compression and subsequent calcination processes. The morphology, chemical composition and microstructure of the as-spun SnO₂/NiO nanowebs were well characterized by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. After the calcination, the thinner and porous nanofibers with a high surface area were obtained. The response of the SnO₂/NiO nanowebs sensor (R_a/R_g = 27.5) is 1 order of magnitude higher than that of the pure SnO₂ nanowebs sensor toward 100 ppm of ethanol with average response and recovery times of ∼2.9 and ∼4.7 s, respectively. Furthermore, the sensor also exhibits high reproducibility and long-term stability. This facile process is versatile for the synthesis of other materials with multilayer nanowebs for different gas sensors and can be extended for various practical applications.