title: Ultrasensitive chemiresistors based on electrospun TiO2 nanofibers.
abstract: 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.
authors.affiliation: Optoelectronic Materials Research Center, Korea Institute of Science and Technology, Cheongryang, Seoul, Republic of Korea.
authors.forename: Il-Doo
authors.initials: ID
authors.lastname: Kim
authors.forename: Avner
authors.initials: A
authors.lastname: Rothschild
authors.forename: Byong Hong
authors.initials: BH
authors.lastname: Lee
authors.forename: Dong Young
authors.initials: DY
authors.lastname: Kim
authors.forename: Seong Mu
authors.initials: SM
authors.lastname: Jo
authors.forename: Harry L
authors.initials: HL
authors.lastname: Tuller
mesh_terms: D003460:Crystallization / Q000379:methods*; D017097:Electric Impedance; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008422:Materials Testing; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D009569:Nitric Oxide / Q000032:analysis* / Q000737:chemistry*; D012399:Rotation; D014025:Titanium / Q000737:chemistry*; D014159:Transducers
chemical_list: C009495:titanium dioxide; D009569:Nitric Oxide; D014025:Titanium