Vertically Aligned ZnO-WO3 Nanorods with Core-Shell Heterostructure for Ethanol Sensing at Low Temperature: In Situ XAS Study

The present study employed a hybrid approach involving hydrothermal and sputtering techniques to produce ZnO-WO₃ composites, which were subsequently evaluated for their suitability as ethanol gas sensors. It is possible to achieve a notable decrease in the operating temperature. SEM and TEM measurements revealed that the diameter of the nanorod film varied from 25 to 100 nm, with a thickness of 2.1 μm. XPS enables the observation of the rise in the number of labile oxygen species. The highest percentage of chemisorbed oxygen species was shown by ZnO-60WO₃, indicating its possible advantage in the development of ethanol sensors. The structural characteristics of the produced film were examined by using the in situ XAS measurement after its exposure to ethanol. It was discovered that 250 °C was the optimum temperature for ethanol detection on ZnO-60WO₃. Based on the findings from SEM, TEM, XPS, and XAS analyses, it has been observed that the enhanced ethanol detection ability of the ZnO-WO₃ sensor is influenced by the quantity of readily reactive oxygen species and surface area. Moreover, the development of a heterogeneous junction between ZnO and WO₃ could also contribute to the enhanced capacity to identify ethanol gas.