Nov, 2006
Humidity-sensitive electrical conductivity of a Langmuir-Blodgett film of titania nanosheets: Surface modification as induced by light irradiation under humid conditions
LANGMUIR
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- Volume
- 22
- Number
- 24
- First page
- 10066
- Last page
- 10071
- Language
- English
- Publishing type
- Research paper (scientific journal)
- DOI
- 10.1021/la0621618
- Publisher
- AMER CHEMICAL SOC
Electrical conductivity of titania nanosheets was investigated for a single-layered Langmuir-Blodgett (LB) film deposited onto a comb-type electrode (5 or 10 mu m(electrode spacing) x 8 mm (electrode width)). The photoresponsive electrical properties of the film were investigated by irradiating with a Xe lamp under various atmospheric conditions. The atmosphere was controlled by introducing either oxygen or nitrogen gases containing different amounts of water vapor. As a result, the LB film behaved as an insulator with little photoresponse under dry atmospheric conditions. It became conductive on illuminating with a Xe lamp under a wet oxygen atmosphere. Conductivity increased with the increase of irradiation time (0-30 min) to attain a stationary value in 1 h. The highest conductive state thus attained lasted for several hours in the dark. The impedance of the film was measured over the frequency range of 1 MHz to 50 Hz by varying the relative humidity of an atmosphere from 0 to 100%. The results were analyzed by assuming an equivalent circuit consisting of one resistance (R) with constant Warburg component (W) and one capacitance (C) in parallel. The R component depended remarkably on the relative humidity, while the C component stayed nearly at the constant value. The dependence of R on water vapor (P-H2O) was expressed by R = A[P-H2O](n) with A = constant and n = -2.9. The results were rationalized in terms of the surface modification of titania nanosheets to hydrophilic nature under the illumination of UV light.
- Link information
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- DOI
- https://doi.org/10.1021/la0621618
- Web of Science
- https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000242022100039&DestApp=WOS_CPL
- URL
- http://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=33846130062&origin=inward
- ID information
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- DOI : 10.1021/la0621618
- ISSN : 0743-7463
- SCOPUS ID : 33846130062
- Web of Science ID : WOS:000242022100039