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The Naked‐Eye Detection of NH 3 –HCl by Polyaniline‐Infiltrated TiO 2 Inverse Opal Photonic Crystals
Author(s) -
Liu Cihui,
Gao Guizhi,
Zhang Yuqi,
Wang Libin,
Wang Jingxia,
Song Yanlin
Publication year - 2012
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201100575
Subject(s) - stopband , naked eye , photonic crystal , polyaniline , materials science , refractive index , blueshift , structural coloration , crystal (programming language) , optics , chemical engineering , analytical chemistry (journal) , optoelectronics , resonator , polymer , chemistry , detection limit , photoluminescence , composite material , organic chemistry , chromatography , physics , computer science , polymerization , programming language , engineering
A reversible color change of a polyaniline‐infiltrated TiO 2 inverse opal photonic crystal (PC) film can be obtained when the PC is switched from an acidic to alkali vapor environment. In a saturated NH 3 environment, the stopband of the as‐prepared PCs changes from 556 to 688 nm; such large shift of 132 nm could be observed, corresponding to a clear color change from green to red. After placing in HCl vapor, the stopband undergoes a blue‐shift and the color turns back to green. The result is ascribed to PANI being doped or dedoped by acid or base and the effective refractive index of the PC film varying accordingly. The naked‐eye detection of NH 3 and HCl vapors can be realized by the reversible color change of the PC film, which is of importance for chemical and biological sensors.