Ultrahigh sensitivity and surface mechanism of gas sensing process in composite material of combining In2O3 with metal-organic frameworks derived Co3O4

The improvement of gas sensor sensitivity and the investigation of the gas sensing mechanism have always been hot issues in the field of gas sensors. It was expected to improve the gas-sensing properties of the material by taking advantage of the large specific surface area and ultrahigh porosities of metal organic frameworks (MOFs) and the advantages of metal oxide semiconductor (MOS) p-n heterojunction in this study. The composite material of combining ZIF-67 derived Co3O4 with In2O3 were synthesized based on micro-flower In2O3 and polyhedral ZIF-67 materials. The systematic ethanol detection demonstrated that sensors based on the material had achieved significant progress in sensitivity and selectivity. An ultra-high sensitivity was achieved with the response value of 5585 to 100 ppm ethanol at 280 °C, and the response time was only 8 s. The heterojunction effect and abundant active sites could be the main reasons for the enhanced performance based on the gas sensing behavior and structural characterization. The gas sensing mechanism of oxygen vacancy was firstly confirmed by the strength rule of In-O bond with the assistance of operando spectroscopy.