Abstract:
This work reports the fabrication of mixed structure of ZnO nanorod on SnO2 thin
film via spray pyrolysis followed by thermal annealing and their gas sensing properties.
ZnO/SnO2 nanostructures are successfully prepared on a gold interdigitated alumina
substrate by spraying varying mixed precursor concentrations of zinc acetate and tin
(IV) chloride pentahydrate solutions in ethanol and thermal annealing. The morphology
of the nanostructures is controlled by tailoring the Zn:Sn ratio in the precursor solution
mixture. Unique ZnO crystals and ZnO nanorods are observed under a field emission
scanning electron microscopy (FESEM) when the Zn/Sn ratio in the precursor solution
is in between 13:7 and 17:3 after thermal annealing. The fabricated nanostructures are
tested for ethanol, methane and hydrogen in air ambient for various gas concentrations
ranging from 25 to 400 ppm and the effect of fabrication conditions on the sensitivity
and selectivity are studied. Among the nanostructure sensors studied, the film fabricated
with molar ratio of Zn/Sn =3:1 shows better sensitivity and selectivity to ethanol due to
high sensing surface area of the nanorod. The response to 25 ppm ethanol is found to
be as high as 50 at an operating temperature of 400◦C.
