Enhanced Methane Sensing Properties of WO₃ Nanosheets with Dominant Exposed (200) Facet via Loading of SnO₂ Nanoparticles.

Methane detection is extremely difficult, especially at low temperatures, due to its high chemical stability. Here, WO₃ nanosheets loaded with SnO₂ nanoparticles with a particle size of about 2 nm were prepared by simple impregnation and subsequent calcination using SnO₂ and WO₃·H₂O as precursors. The response of SnO₂-loaded WO₃ nanosheet composites to methane is about 1.4 times higher than that of pure WO₃ at the low optimum operating temperature (90 °C). Satisfying repeatability and long-term stability are ensured. The dominant exposed (200) crystal plane of WO₃ nanosheets has a good balance between easy oxygen chemisorption and high reactivity at the dangling bonds of W atoms, beneficial for gas-sensing properties. Moreover, the formation of a n⁻n type heterojunction at the SnO₂-WO₃ interface and additionally the increase of specific surface area and defect density via SnO₂ loading enhance the response further. Therefore, the SnO₂-WO₃ composite is promising for the development of sensor devices to methane.