Novel Two-Dimensional WO₃/Bi₂W₂O₉ Nanocomposites for Rapid H₂S Detection at Low Temperatures

Compared with single-component metal oxides, multicomponent metal oxides show good gas sensing performance in the field of gas sensing, but they still need to be further improved in terms of rapid response. In this paper, a two-dimensional flaky WO₃/Bi₂W₂O₉ composite material with a thickness of about 32.3 nm was synthesized by a simple solvothermal method. The composite has good sensing performance and selectivity toward H₂S. When the operating temperature is as low as 92 °C, the response to 100 ppm H₂S reaches 84.18, and the response time is 2 s, which is extremely fast due to the open system of the two-dimensional nanosheet. A combination of gas chromatography-mass spectrometry (GC-MS) and X-ray photoelectron spectroscopy (XPS) is used to analyze the changes of H₂S and the surface chemistry of WO₃/Bi₂W₂O₉ composite materials; the sensing mechanism of H₂S was studied by a Kelvin probe and UV diffuse reflection. Compared with the pure phase WO₃ and Bi₂W₂O₉, good gas sensing properties of the WO₃/Bi₂W₂O₉ composite may be due to its unique heterostructure. This is the first application of WO₃/Bi₂W₂O₉ in the field of gas sensing and is of great significance for the rapid detection of H₂S at low temperatures for multicomponent metal oxides.