Enhanced ethanol sensing performance using Co3O4–ZnSnO3 arrays prepared on alumina substrates

In this work, novel n-type heterostructures of ZnSnO3 modified p-type Co3O4 (Co3O4–ZnSnO3) nanowire arrays were fabricated in-situ on flat alumina substrates via a simple hydrothermal method without seed layers. SEM and TEM characterizations revealed that the Co3O4 nanowire arrays were fully covered by ZnSnO3 nanosheets. The gas-sensing measurement revealed that the Co3O4–ZnSnO3 composite arrays showed the highest response 5.57 (Rg/Ra) towards ethanol, which was 2.04 times higher than that of Co3O4 nanowire arrays (Rg/Ra = 2.73). Meanwhile, the enhanced sensing mechanism of Co3O4–ZnSnO3 composite arrays was also discussed, which could be explained by the special heterojunction structure arrays that offered an additional modulation in resistance. Our studies shed a new light to design p-n heterostructure arrays in-situ sensing device by a facile method. Moreover, the as-designed Co3O4–ZnSnO3 composite arrays have potential application for fabricating high performance ethanol sensors.