MOF-derived porous hierarchical ZnCo2O4 microflowers for enhanced performance gas sensor

Abstract

Metal-organic framework (MOF)-derived ZnCo2O4 was synthesized by utilizing the template agent 2-methylimidazole, zinc and cobalt nitrate by an easy solvothermal process followed by annealing for the first time. The porous hierarchical ZnCo2O4 microstructure possesses a microflower structure assembled by 3D nanosheets. The obtained flower-like structure has abundant open spaces between nanosheets, which allows for facile gas diffusion while providing plentiful active sites for gas adsorption. The hierarchical ZnCo2O4 microflower-based sensor exhibits a high response of 32.32 and fast response/recovery rates (2.6/8.8 s) at 200 °C to 100 ppm acetone gas. In addition, the porous hierarchical ZnCo2O4 microflower-based sensor has a detection limit below 50 ppb with a response of 2.51 to acetone gas. The excellent sensing performance of this porous hierarchical structure-based sensor is ascribed to the good gas accessibility of the microflower morphology with a high specific surface area, small particle size and highly porous structure. This work explores an efficient way to synthesize MOF-derived bimetallic oxides with microflower structures assembled by 3D nanosheets for gas sensing applications.