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Enhanced Photocatalytic Activity of Zeolite‐Encapsulated TiO 2 Clusters by Complexation with Organic Additives and N‐Doping
Author(s) -
Alvaro Mercedes,
Carbonell Esther,
Fornés Vicente,
García Hermenegildo
Publication year - 2006
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200500264
Subject(s) - photocatalysis , zeolite , inorganic chemistry , chemistry , absorption band , titanium dioxide , photochemistry , aqueous solution , catechol , oxide , materials science , catalysis , organic chemistry , physics , optics , metallurgy
In the literature it was found that titanium oxide clusters of a few metal atoms encapsulated inside the micropores of zeolite Y exhibit large blue shifts in the TiO ligand‐to‐metal charge‐transfer band as compared to non‐encapsulated bulk titanium dioxide particles. This blue shift of the TiO absorption band is believed to have a negative effect on the photocatalytic activity of zeolite‐encapsulated TiO 2 . We report here on circumventing this problem and increasing visible‐light absorption by means of a red shift of the absorption band caused by addition of some organic molecular modifiers containing acidic OH groups that can strongly bind with titanol groups TiOH. In the studied series of zeolite‐encapsulated TiO 2 samples, the red shift of the optical spectrum follows the order: catechol>4‐aminobenzoic acid>benzoic acid. Also N‐doping of zeolite‐encapsulated TiO 2 clusters by thermal treatment with urea leads to a red shift of the TiO 2 absorption band that depends on the annealing and hydration conditions. By comparison to the degradation of phenol in aqueous solution, we have demonstrated that these changes in the absorption spectrum on addition of the organic modifier are also reflected in the photocatalytic activity of the samples; a greater increase in photocatalytic activity (about 30 %) was observed for the additive catechol.