Electrospun ZnO Nanotubes Decorated with Zinc Ferrite Nanoparticles as Sensing Material for Hydrogen Sulfide Detection

Coaxial electrospinning is first employed for loading zinc ferrite (ZnFe₂O₄) nanoparticles onto zinc oxide (ZnO) nanotubes for sensing hydroxide sulfite (H₂S) in the gaseous phase. The obtained ZnFe₂O₄/ZnO composite consists of protruding ZnFe₂O₄ nanoparticle-decorated inner ZnO nanotubes, forming a unique double-layer core–shell structure with a large amount of p–n heterojunction interfaces and oxygen vacancy defects. The nanotubes have a diameter range from 47 to 88 nm and a wall thickness range from 17 to 46 nm. The ZnFe₂O₄/ZnO sensors demonstrate enhanced sensitivity, selectivity, and fast response to H₂S gas compared to the ZnO nanowire sensor, particularly at lower operating temperatures (50–240 °C). With the molar ratio of zinc nitrate to iron nitrate at 7:3, the derived ZnFe₂O₄/ZnO sensor had maximal responses of 3.3–98.5 to H₂S at 0.1–10 ppm under the optimal temperature of 130 °C, significantly higher than that of the ZnO nanowire sensor. The significant enhancement in H₂S-sensing is attributed to the synergistic effect between the ZnFe₂O₄ and ZnO species and the presence of abundant oxygen vacancies. This research suggests exploiting high-performance H₂S-sensing materials based on coaxial electrospinning.