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

A carbon nanomaterials-modified MOF-derived Co 3 O 4 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 Co 3 O 4 mesoporous structures was carefully studied. The gas sensing results revealed that the sensor based on the CNT-rGO-Co 3 O 4 nanocomposites exhibited better gas sensing properties toward the ethanol gas, including higher response, admirable antihumidity, and shorter response–recovery time than the other Co 3 O 4 samples. The gas sensitivity of CNT-rGO-Co 3 O 4 nanocomposites reached to be as high as 127.1, which was 5.8 times higher than that of a pure Co 3 O 4 gas sensor when exposed to 100 ppm ethanol. The enhanced gas sensing performance of the sensor fabricated by the CNT-rGO-Co 3 O 4 nanocomposites could be attributed to the promising synergistic effect between carbon nanomaterials and Co 3 O 4 nanobox, implying that the heterojunction structure and coupling effect would dramatically optimize the gas sensing reaction process, resulting in improved gas sensing performance.