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Polymeric Adsorption of Methylene Blue in TiO 2 Colloids—Highly Sensitive Thermochromism and Selective Photocatalysis
Author(s) -
Liu Baoshun,
Wen Liping,
Nakata Kazuya,
Zhao Xiujian,
Liu Shanhu,
Ochiai Tsuyoshi,
Murakami Taketoshi,
Fujishima Akira
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201200178
Subject(s) - trimer , photocatalysis , methylene blue , methyl orange , cationic polymerization , adsorption , photochemistry , thermochromism , monomer , materials science , visible spectrum , crystal violet , chemistry , chemical engineering , polymer chemistry , organic chemistry , polymer , dimer , catalysis , medicine , optoelectronics , pathology , engineering
The polymeric adsorption of methylene blue (MB) on a TiO 2 surface is reported. The MB molecule on the TiO 2 surface mainly exists as the H‐trimeric adsorption state, which results in the MB@TiO 2 polymeric sol. The trimeric adsorption leads to a remarkable “blueshift” of visible‐light adsorption of MB. Electrostatic attraction is important for trimeric adsorption of MB on TiO 2 surfaces. The trimer–monomer equilibrium is highly sensitive on temperature changes, showing an interesting reversible thermochromism. The MB@TiO 2 polymeric sol can be photodegraded under UV illumination without destroying the equilibrium of trimer–monomer. Compared with anionic methyl orange, the TiO 2 colloid hydrosol shows highly selective photocatalysis of MB and other cationic dyes, including crystal violet, methylene green, and victoria blue B. The MB@TiO 2 polymeric sol is stable under visible‐light illumination because interfacial transfer of electrons does not exist between MB and TiO 2 .