Nanostructured semiconducting metal oxides and particularly single nanowire devices offer exceptional gas sensitivity but at the expense of statistical variations and excessive noise levels. In this study TiO2/poly(vinyl acetate) composite nanofiber mats were directly electrospun onto interdigitated Pt electrode arrays, hot pressed at 120 degrees C, and calcined at 450 degrees C. This resulted in a novel multiple nanowire network composed of sheaths of 200-500 nm diameter cores filled with readily gas accessible approximately 10 nm thick single-crystal anatase fibrils. TiO2 nanofiber sensors tested for NO2, in dry air, exhibited exceptional sensitivity showing with, for example, a 833% increase in sensor resistance when exposed to 500 ppb NO2 at 300 degrees C, consistent with a detection limit estimated to be well below 1 ppb. Unusual response patterns were observed at high NO2 concentrations (> 12.5 ppm), consistent with n to p inversion of the surface-trap limited conduction facilitated by the high surface-to-volume ratio of this material.

Nanostructured semiconducting metal oxides and particularly nanofiber-based photoelectrodes can provide enhanced energy conversion efficiencies in dye-sensitized solar cells ͑DSSCs͒. In this study ZnO/poly͑vinyl acetate͒ composite nanofiber mats were directly electrospun onto a glass substrate coated with F : SnO 2 , then hot pressed at 120°C and calcined at 450°C. This resulted in multiple nanofiber networks composed of a twisted structure of 200-500 nm diameter cores with ϳ30 nm single grains. The DSSCs using ZnO nanofiber mats exhibited a conversion efficiency of 1.34% under 100 mW/ cm 2 ͑AM-1.5G͒ illumination.