Humidity-Sensitive Electrical Conductivity of a Langmuir−Blodgett Film of Titania Nanosheets: Surface Modification as Induced by Light Irradiation under Humid Conditions
| Autor: | Takayuki Wakayama, Toshihiro Kogure, Kosho Akatsuka, Kazuko Saruwatari, Masa-aki Haga, Takayoshi Sasaki, Akihiko Yamagishi, Masanori Iitake, Hisako Sato |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
business.industry
Analytical chemistry chemistry.chemical_element Surfaces and Interfaces Conductivity Condensed Matter Physics Oxygen Langmuir–Blodgett film Optics chemistry Electrical resistivity and conductivity Electrode Electrochemistry General Materials Science Relative humidity business Electrical conductor Spectroscopy Water vapor |
| Zdroj: | Langmuir. 22:10066-10071 |
| ISSN: | 1520-5827 0743-7463 |
| DOI: | 10.1021/la0621618 |
| Popis: | Electrical conductivity of titania nanosheets was investigated for a single-layered Langmuir-Blodgett (LB) film deposited onto a comb-type electrode (5 or 10 microm (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 (PH2O) was expressed by R = A[PH2O]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. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|