Enhanced H2S gas sensing performance of ZnFe2O4/ZnO composite thick films synthesized via hydrothermal method

Abstract A hydrothermal method was employed to synthesize pure ZnFe 2 O 4 and the composite nanomaterial ZnFe 2 O 4 /ZnO. The crystal structure, phase purity and particle size were characterized using powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) with selected area electron diffraction (SAED). Optical properties were studied through UV–visible absorption and FTIR spectroscopy. To explore their potential applications, pure ZnFe 2 O 4 and ZnFe 2 O 4 /ZnO composite nanomaterials were used to fabricate thick-film gas sensors via screen printing. The surface morphology and elemental composition of the thick films were examined using field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray spectroscopy (EDS). The activation energy of both pure and composite nanomaterials was also evaluated. Gas sensing properties were investigated by measuring the sensor response to various probe gases (CO 2 , CO, H 2 , NH 3 , Cl 2 , and H 2 S) at different operating temperatures. The gas sensing tests revealed that the ZnFe 2 O 4 /ZnO composite sensor demonstrated superior sensitivity, faster response, and recovery times for 500 ppm H 2 S gas at lower operating temperatures compared to pure ZnFe 2 O 4 . These enhanced properties can be attributed to the unique rough, porous structure of the ZnFe 2 O 4 /ZnO composite and the heterojunction interactions at the ZnFe 2 O 4 /ZnO interfaces.