Modulation of rGO-Co3O4 heterojunction with multi-walled carbon nanotubes for efficient ethanol detection

A carbon nanomaterials-modified MOF-derived Co3O4 p–p heterojunction was successfully constructed using a solution-combination-calcination method. The morphological and structural characteristics and their gas sensing performances were comprehensively investigated. Particularly, the synergistic effect between different carbon nanomaterials and Co3O4 mesoporous structures was carefully studied. The gas sensing results revealed that the sensor based on the CNT-rGO-Co3O4 nanocomposites exhibited better gas sensing properties toward the ethanol gas, including higher response, admirable antihumidity, and shorter response–recovery time than the other Co3O4 samples. The gas sensitivity of CNT-rGO-Co3O4 nanocomposites reached to be as high as 127.1, which was 5.8 times higher than that of a pure Co3O4 gas sensor when exposed to 100 ppm ethanol. The enhanced gas sensing performance of the sensor fabricated by the CNT-rGO-Co3O4 nanocomposites could be attributed to the promising synergistic effect between carbon nanomaterials and Co3O4 nanobox, implying that the heterojunction structure and coupling effect would dramatically optimize the gas sensing reaction process, resulting in improved gas sensing performance.