Pd@Co3O4/In2O3 hollow microtubes derived from core-shell MOFs as materials for conductometric trace toluene detection

In this work, we designed and prepared Pd-loaded Co3O4/In2O3 hollow microtubes heterostructures, which are promising for trace toluene gas detection in humid atmosphere. We characterized the materials, confirmed the morphology of hollow microtubes and structure of the heterojunctions, and analyzed the effect of components and Pd NPs loading on the gas sensing performance. In gas sensing measurements, the Pd@Co3O4/In2O3 (PdCoIn-2) sensor shows high responses (21.5/16.4, 1 ppm), low limit of detections (LODs, 0.02/0.06 ppb), with fast response and recovery times (1 and 4 s/1 and 3 s) toward toluene under 54 %/95 % RH. In addition, PdCoIn-2 sensor also exhibits excellent selectivity, repeatability and long-term stability. Finally, based on the structure of this material, the enhanced sensing mechanism of PdCoIn-2 for toluene detection is discussed in depth.