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.