Construction of core–shell Fe2O3@SnO2 nanohybrids for gas sensors by a simple flame-assisted spray process

Abstract

In this paper, core–shell Fe₂O₃@SnO₂ nanohybrids were fabricated via a simple flame-assisted spray pyrolysis (FASP) process. A shell layer composed of SnO₂ nanocrystals (8–10 nm) was grown in situ on the pristine Fe₂O₃ nanoparticles, with a tailored thickness ranging from 6–20 nm. The construction of such an intriguing structure thus provided a rational and efficient combination of two kinds of gas sensitive materials, resulting in a remarkably enhanced sensing ability (R_a/R_g) and good selectivity in the detection of 22.8 to 100 ppm ethanol vapor at 300 °C, compared to the corresponding pure Fe₂O₃ and SnO₂ materials synthesized by FASP. This enhancement can be mainly attributed to the synergistic effects arising from the presence of both of these materials, i.e. the change of the heterojunction barrier height at the Fe₂O₃/SnO₂ interface. In addition, the in situ flame coating process provides a promising and versatile choice for the synthesis of core–shell nanostructures with multifunctional compositions.