Solvothermally synthesized tungsten oxide nanowires/nanorods for NO2 gas sensor applications

One-dimensional nanorods or nanowires of W18O49 were synthesized by solvothermal method at 200 °C with tungsten hexachloride (WCl6) as precursor and cyclohexanol or 1-propanol as reaction solvent. Their morphology and structure properties were systematically characterized. The NO2-sensing properties of the sensors based on nanowires and nanorods were investigated at 100 °C up to 250 °C over NO2 concentration ranging from 1 ppm to 20 ppm. The results indicate that both nanowires and nanorods exhibit reversible response to different concentrations of NO2, and the highest gas response is achieved at 150 °C. In comparison with nanorods, nanowires showed a much quicker response characteristic and a relative higher response value to the same concentration of NO2 gas due to the smaller diameter and larger specific surface area.

► Tungsten oxide nanowires and nanorods were solvothermally synthesized by changing reaction solvent.
► The sensing characteristics of the tungsten oxide nanowires and nanorods sensors to NO2 gas were evaluated in detail.
► The response time and recovery time for the nanowires or nanorods sensors are much shorter than the oxide nanoparticles or sputtered films.
► The nanowires sensor shows a much shorter response time and a relative higher response value to NO2 gas than the nanorods one.
► The NO2-sensing mechanism and the possible reason for the better gas sensing properties of the nanowires are analyzed.