Heterostructure of CuO microspheres modified with CuFe2O4 nanoparticles for highly sensitive H2S gas sensor

Highly sensitive hydrogen sulfide (H2S) gas sensors were developed from a semiconducting heterostructure composed of CuO microspheres whose surface was modified with CuFe2O4 nanoparticles. The CuO microspheres were fabricated utilizing a simple heating route carried out in a water bath, while CuFe2O4 modification of CuO was carried out by a facile two-step method. The morphology and characteristics of the samples were examined by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and inductively coupled plasma atomic emission spectrometry. The H2S gas sensing properties were examined at different operating temperatures, and their dependence on molar ratio of CuFe2O4 to CuO was also investigated. Results showed that the response of the optimized CuFe2O4-modified CuO heterostructures to 10 ppm H2S gas was approximately 20 times higher than that of the initial CuO microspheres at the optimal operating temperature (240 °C). Moreover, a fast response/recovery was also noticed, and the mechanism for enhanced sensing properties of such heterostructures was thoroughly discussed.