General and scalable route to synthesize nanowire-structured semiconducting metal oxides for gas-sensor applications

The development of a general, low-cost, and scalable method for synthesizing nanowire (NW) structures made of different materials for use in the fast and accurate detection of toxic and flammable gases is extremely important for monitoring environmental pollution and gas leakage. This study reports on a scalable and general route for synthesizing nanowire-structured semiconducting metal oxides for gas nanosensors. Different metal oxide nanowires made of titanium oxide, tin oxide, zinc oxide, copper oxide, and tungsten oxide, were synthesized via sputter deposition of correlative metals over porous single-walled carbon nanotubes (SWNTs) templates followed by oxidation. The microstructures and morphologies of the metal oxide nanowires were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results showed that the synthesized materials could be nanowires or bead-like nanowires, depending on the adhesion between the deposited metals and the SWNTs substrates. Different metal oxide nanowires with lengths of up to several micrometers and controllable diameters could be easily synthesized and were found to be suitable for gas sensor applications. This synthetic method is expected to introduce new strategies and promised potential applications for NWs in other fields, such as in photocatalysts, electrochemicals, and biosensors.

► We have demonstrated an effective method for scalable fabrication of metal oxide nanowires.
► Gas sensing performance of various metal oxide was systemically compared.
► The results show a potential method for production of gas sensors at industrial level.