Electrospinning Encapsulation of Pd Nanoparticles into α-Fe2O3 Nanofibers Windows Enhanced Acetone Sensing

Different concentrations (0, 1 mol%, 2 mol%, 6 mol% and 8 mol%) of palladium (Pd) nanoparticles modified hematite nanofibers (Pd NPs@ $\alpha $ -Fe2O3 NFs) were successfully synthesized via a facile electrospinning method followed by the calcination treatment. Their surface morphologies, crystal structures and chemical compositions were subsequently characterized in order to find optimum modification percentage. The gas sensing experiments on Pd NPs@ $\alpha $ -Fe2O3-based gas sensors revealed that encapsulation of Pd NPs into $\alpha $ -Fe2O3 NFs could significantly improve their sensing performances. Specifically, the as-prepared Pd4/Fe gas sensor exhibited higher response ( $\text{R}_{air}/\text{R}_{gas} =16.6$ ) toward 100 ppm acetone at 220°C, which was 3.4 times higher than that of Pd0/Fe sensor (4.89). Meanwhile, the Pd4/Fe sensor also showed shorter response/recovery (4 s/4 s), low limit of detection (LOD) (50 ppb) and good selectivity and long-term stability. The enhanced gas sensing properties of Pd NPs@ $\alpha $ -Fe2O3-based gas sensors could be attributed to the chemical and electronic sensitization of Pd NPs.