Effects of Al doping on SnO₂ nanofibers in hydrogen sensor

Pristine SnO₂ and Al-doped SnO₂ composite nanofibers, with several dopants concentrations, have been fabricated via electrospinning technique and subsequent calcination procedure. The morphology, structure, and composition of the as-prepared nanofibers are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive X-ray spectrometer (EDX), respectively. XRD analysis indicates Al-SnO₂ metastable solid solution is formed at the low concentrations, while the Al ₂O₃-SnO₂ heterojunction structures can be obtained at high concentrations. Comparing with the pristine SnO₂ nanofibers, Al-doped SnO₂ composite nanofibers show improved hydrogen sensing properties, with the Al-SnO₂ metastable solid solution having the best performances, such as higher sensitivity and rapid response (∼3 s) and recovery (less than 2 s). Effects of the changes of SnO ₂ crystal, causing by the induction of Al, on the sensing performance have been discussed. We believe this paper can construct a powerful platform to understand and design the practical gas sensor in future.