Large-area alignment of Tungsten oxide nanowires over flat and patterned substrates for room-temperature gas sensing

Alignment of nanowires over a large area of flat and patterned substrates is a prerequisite to use their collective properties in devices such as gas sensors. In this work, uniform single-crystalline ultrathin W₁₈O₄₉ nanowires with diameters less than 2 nm and aspect ratios larger than 100 have been synthesized, despite their flexibility, assembled into thin films with high orientational order over a macroscopic area by the Langmuir-Blodgett technique. Alignment of the tungsten oxide nanowires was also possible on top of sensor substrates equipped with electrodes. Such sensor devices were found to exhibit outstanding sensitivity to H₂ at room temperature.