Crystallite size control in MOF-5-derived nanostructured ZnO sensors for detecting 1-pentanol

Metal oxide semiconductor sensors derived from metal-organic frameworks (MOFs) possess the potential to detect and recognize microbial volatile organic compounds (MVOCs). These materials hold promises for environmental, industrial, and medical monitoring applications. However, research on the influence of metal oxide crystallite sizes on sensor performance remains relatively limited. Consequently, we present the synthesis, characterization, and application of MOF-derived ZnO nanoparticles with varying crystallite sizes for the detection of MVOCs. The ZnO precursor utilized in this study was MOF-5, synthesized through a microwave-assisted solvothermal (MAS) method. Subsequently, MOF-5 was calcined at varying temperatures of 450, 600, and 800 °C to produce ZnO nanoparticles with sizes of 17.8 nm at 450 °C (ZnO-450), 26.8 nm at 600 °C (ZnO-600), and 34.3 nm at 800 °C (ZnO-800). These materials were evaluated as sensors to detect six distinct MVOCs (100 ppm) at operating temperatures ranging from 200 °C to 450 °C in dry air, including acetone, 2-butanone, m-xylene, toluene, benzene, and 1-pentanol. The ZnO-450 sensor, characterized by the smallest crystallite size, exhibited the highest response, reaching 2680.0, to 1-pentanol at 400 °C. On the other hand, the ZnO-600 sensor, with a middle crystallite size, demonstrated an excellent response of 2205.0 to detect 1-pentanol at 400 °C in dry conditions. Notably, ZnO-600 exhibited superior selectivity for 1-pentanol compared to ZnO-450 and ZnO-800. Therefore, our findings demonstrated that the varying crystallite sizes of ZnO nanoparticles significantly impact sensor response and selectivity for 1-pentanol. Furthermore, the ZnO-600 sensor demonstrated satisfactory performance across a range of controlled relative humidity levels.