Facile Fabrication of ZnO-ZnFe 2 O 4 Hollow Nanostructure by a One-Needle Syringe Electrospinning Method for a High-Selective H 2 S Gas Sensor.

Herein, a facile fabrication process of ZnO-ZnFe 2 O 4 hollow nanofibers through one-needle syringe electrospinning and the following calcination process is presented. The various compositions of the ZnO-ZnFe 2 O 4 nanofibers are simply created by controlling the metal precursor ratios of Zn and Fe. Moreover, the different diffusion rates of the metal oxides and metal precursors generate a hollow nanostructure during calcination. The hollow structure of the ZnO-ZnFe 2 O 4 enables an enlarged surface area and increased gas sensing sites. In addition, the interface of ZnO and ZnFe 2 O 4 forms a p-n junction to improve gas response and to lower operation temperature. The optimized ZnO-ZnFe 2 O 4 has shown good H 2 S gas sensing properties of 84.5 (S = R a /R g ) at 10 ppm at 250 °C with excellent selectivity. This study shows the good potential of p-n junction ZnO-ZnFe 2 O 4 on H 2 S detection and affords a promising sensor design for a high-performance gas sensor.