Fabrication of MOF-derived porous Au@Co-ZnO nanostructures with excellent C₂H₅OH sensing performance

Introduction: Zinc oxide (ZnO) is an n-type semiconductor with a wide bandgap, excellent electron mobility, and stable chemical characteristics, making it have potential for application in the field of gas sensing. However, conventional ZnO-based gas sensors face challenges such as high operating temperatures and low sensitivity.

Materials and Methods: In this paper, we first synthesized ZIF-8 with a rhombic dodecahedron structure using a room-temperature chemical precipitation method. By doping ZIF-8 with cobalt (Co) and exchanging gold ions, followed by calcination in air, we obtained a metal-organic framework (MOF) derived porous Au@Co-ZnO nanostructure.

Results: This nanostructure retained the large specific surface area and porous characteristics of ZIF-8, while its gas sensing performance was significantly enhanced compared to the pure MOF-derived ZnO nanostructure, due to Co doping and gold nanoparticle modification. At an ethanol concentration of 100 ppm, the Au@Co-ZnO sample demonstrated its best performance at 140 °C, with a response value of 205.3. This result was 28.9 times higher compared to the pure ZnO sample, which showed a response value of 7.1 under identical conditions. Additionally, the optimal operating temperature was 40 °C lower than that of the pure ZnO sample (180 °C). Furthermore, the Au@Co-ZnO samples demonstrated good stability and selectivity for ethanol gas.

Discussion: The proposed MOF-derived porous Au@Co-ZnO nanostructures not only advance the application of MOF-derived materials in gas detection but also offer a novel approach for boosting the gas-sensing performance of other metal oxide materials.