MOF-derived Co3O4 hierarchical porous structure for enhanced acetone sensing performance with high sensitivity and low detection limit

Metal organic frameworks (MOFs) with unique interior structure play a significant role in the field of gas-sensing. In this research, Co3O4-x hierarchical porous structure is successfully prepared by the solvothermal method and subsequent heat treatment using MOF as a sacrificial template. The effect of cobalt sources with different proportions of cobalt nitrate and cobalt chloride on the morphology, structure and gas-sensing of as-prepared Co3O4-x (x = 0, 1, 2, 3) samples is characterized and investigated in details by various techniques of XRD, Raman, SEM, TEM, BET and XPS. The findings demonstrate that the typical Co3O4-2 sensor exhibits a significantly higher response (27.6) than Co3O4-0 (6.1) to 50 ppm acetone at 140 °C. Furthermore, Co3O4-2 sensor exhibits fairly low detection limit of 0.1 ppm, superior selectivity, repeatability, and long-term stability. The optimized acetone-sensing capability of the as-obtained Co3O4-x samples may be ascribed to the hierarchical porous structure composed of the adhered nanoparticles due to the slow dissolution of CoCl2·6H2O, which is beneficial to increasing electron transport channels, thus improving gas sensitivity. The work provides a new idea for the preparation of respiratory monitoring materials for diabetic patients.