Fabrication of novel flower-like Co3O4 structures assembled by single-crystalline porous nanosheets for enhanced xylene sensing properties

In this paper, novel flower-like Co3O4 structures have been fabricated by an ethylene glycol (EG) mediated solvothermal with the co-assistant of water and polyvinyl pyrrolidone (PVP). It was found that the water and PVP played a key role in the formation process. The structure and morphology of the as-prepared products were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The results revealed that the flower-like Co3O4 was assembled by single-crystalline porous nanosheets. Due to the structural stability of single-crystalline nanosheets, the flower-like hierarchical porous structures can be well kept during the sensor-fabrication processed. Notably, gas-sensing tests revealed that the flower-like Co3O4 showed a high response (Rg/Ra = 79.8-100 ppm) to xylene at its optimized temperature (150 °C), which was 4 times higher than that of commercial Co3O4 (Rg/Ra = 19.1). Moreover, the flower-like Co3O4 also exhibited excellent long-term stability with small deviations (3.1%) for two months. The enhanced gas-sensing performances of flower-like Co3O4 were mainly attributed to the structural stability of single-crystalline porous nanosheets as building blocks. Combined with its high selectivity and low detection limit, the as-prepared novel flower-like Co3O4 assembled by single-crystalline porous nanosheets is a highly promising gas-sensing material for xylene detection.