Porous ZnO Nanofibers Sensitized with Au Nanoclusters for Sensing BTX Gases

The detection of benzene, toluene, and m-xylene (BTX) using chemiresistive metal oxide sensors remains challenging, owing to their low chemical reactivity and stable structures. Compared to conventional noble metal nanoparticles, well-defined noble metal nanoclusters (NCs) exhibit superior catalytic activity, making them promising candidates to modify metal oxides as sensing materials for enhancing gas-sensing performance to BTX. In this study, we employed three thiolate-capped molecular Au NCs [Au25(SG)18, Au144(SR)60, and Au807(SG)163] with distinct core diameters as precursors. Through electrospinning, followed by thermal oxidation, Au NC-sensitized ZnO porous nanofibers were successfully fabricated. Gas-sensing evaluations revealed that Au NC-sensitized ZnO porous nanofibers exhibited significantly enhanced responses to BTX gases. Notably, Au25 NC-sensitized ZnO porous nanofibers demonstrated the highest sensitivity, along with excellent stability and reproducibility. Additionally, a clear size-dependent sensing effect was observed, where the sensor response decreased as the Au NC size increased. The underlying mechanisms responsible for the enhanced sensing performance and size dependence were further discussed. This work provides a general strategy for developing noble metal NC-sensitized one-dimensional metal oxide porous nanofibers for high-performance gas-sensing applications.