Fabrication of Ag₂O/WO₃ based sensors for detection of hydrogen sulfide

Several metal oxides, such as tungsten oxide (WO3), are considered superior sensing materials for hydrogen sulfide (H2S) detection in the ambient environment. In this study, silver loaded tungsten oxide nanoparticles were prepared by microwave-assisted chemical route. Nanoparticle thin films were deposited on substrates with electrical electrodes to explore their gas sensing and electrical properties. The morphology, crystal structure, and chemical state were examined using x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS). The sensing properties of the sample were tested at different temperatures varying from room temperature to 200 degrees C. The Ag2O/WO3 nanoparticles showed enhanced H2S sensing abilities at very low temperatures (close to room temperature) and concentrations as low as 10 ppm compared to bare WO3. Moreover, the effect of annealing and comparison with physical mixing was studied and showed that non-annealed Ag-loaded WO3 produced the best response. The results can be attributed to the decrease in the energy bandgap due to increasing the Ag content and the strong interaction between the Ag and WO3 and silver to silver oxide transformation at low annealing temperatures. This study demonstrates that Ag2O/WO3 sensors offer enhanced low-temperature sensing with reasonable response time, low operating power, and simple fabrication that can be promising sensors for H2S, which may be utilized as wearable devices and in the industrial setting. (C) 2021 The Authors. Published by Elsevier B.V.