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Gasochromic effect of palladium doped peroxopolytungstic acid films prepared by the sol-gel route |
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| Authors: | B Orel N Grošelj UOpara Krašovec M Gabrš?ek P Bukovec R Reisfeld[Author vitae] |
| Affiliation: | a National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia b Faculty of Chemistry, University of Ljubljana, 1000 Ljubljana, Slovenia c Department of Chemistry, Hebrew University, Jerusalem, Israel |
| Abstract: | Gasochromic palladium doped peroxopolytungstic acid (Pd:P-PTA) films have been prepared using dip-coating deposition from peroxopolytungstic acid (P-PTA) sols into which PdCl2 was added in molar ratios Pd:W=1:125, 1:100, 1:53, and 1:40. These films exhibit reversible colouring/bleaching changes when exposed to hydrogen or hydrogen/argon mixture (4%) and air, alternatively. Gasochromically coloured and bleached films were characterised using in-situ Fourier transform infrared (FT-IR) spectroscopy. The vibrational modes of as-deposited, coloured and bleached films were assigned and the polaron absorption, which characterises the IR spectra of coloured films, was detected. Colouring/bleaching kinetics of films exposed to H2 and H2/Ar mixture as a function of the concentration of the catalyst and temperature of heat-treatment is reported. Proton (σpr) and electronic (σel) conductivities determined from impedance spectra revealed an increase in σel from 10−5 S cm−1 in bleached state, to 10−3 S cm−1 in coloured state, while σpr remained constant (10−2 S cm−1). |
| Keywords: | Gasochromism Pd doped P-PTA films In-situ IR transmission and reflection–absorption spectra LO mode |
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