Enhanced triethylamine-sensing properties of P-N heterojunction Co3O4/In2O3 hollow microtubes derived from metal–organic frameworks

Triethylamine (TEA) sensors with excellent sensitivity and selectivity are in great demand to monitor the concentration change in the real environments. Herein, we presented a metal-organic framework (MOF)-driven sensor onto semiconducting metal oxide (SMO) hollow microtubes (HMs) via hydrothermal and annealing processes for markedly enhanced chemical gas sensing. The Co3O4/In2O3 HMs derived from CoII-impregnated MIL-68(In) are employed structural analyses which confirm that the n-type In2O3 and p-type Co3O4 are successfully combined and form heterojunctions at Co3O4/In2O3 interfaces. The gas-sensing properties of Co3O4/In2O3 HMs towards TEA are evaluated, and particularly, the sensing device based on Co3O4/In2O3 HMs with 2.5 wt.% of Co to MIL-68(In) (Co3O4/In2O3 (2.5 wt.%)) is found to exhibit unprecedented TEA sensitivity (Rair/Rgas = 786.8–50 ppm) and low detection limit (Rair/Rgas = 6.5–2 ppm), which are upgrade to more 2.4 and 1.8 times than those of intrinsic In2O3, respectively, and superior selectivity against other interfering gases. The significantly enhanced TEA sensing behavior is largely attributed to a combination of changing electronic structures, and increasing oxygen vacancy and surface chemisorbed oxygen. The present Co3O4/In2O3 HMs shows a novel and promising platform for the practical application to selectively detect TEA vapor at relatively low temperature.