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Enhancing the Photocatalytic Activity of Sr 4 Al 14 O 25 : Eu 2+ , Dy 3+ Persistent Phosphors by Codoping with Bi 3+ Ions
Author(s) -
García Carlos R.,
Oliva Jorge,
Romero Maria Teresa,
DiazTorres Luis A.
Publication year - 2016
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.12570
Subject(s) - phosphor , photocatalysis , orthorhombic crystal system , irradiation , materials science , bismuth , luminescence , analytical chemistry (journal) , dopant , nuclear chemistry , methylene blue , doping , mineralogy , crystal structure , chemistry , crystallography , optoelectronics , catalysis , metallurgy , chromatography , nuclear physics , biochemistry , physics
The photocatalytic activity of Bismuth‐codoped Sr 4 Al 14 O 25 : Eu 2+ , Dy 3+ persistent phosphors is studied by monitoring the degradation of the blue methylene dye UV light irradiation. Powder phosphors are obtained by a combustion synthesis method and a postannealing process in reductive atmosphere. The XRD patterns show a single orthorhombic phase Sr 4 Al 14 O 25 : Eu 2+ , Dy 3+ , Bi 3+ phosphors even at high Bismuth dopant concentrations of 12 mol%, suggesting that Bi ions are well incorporated into the host lattice. SEM micrographs show irregular micrograins with sizes in the range of 0.5–20 μm. The samples present an intense greenish‐blue fluorescence and persistent emissions at 495 nm, attributed to the 5d–4f allowed transitions of Eu 2+ . The fluorescence decreases as Bi concentration increases; that suggest bismuth‐induced traps formation that in turn quench the luminescence. The photocatalytic evaluation of the powders was studied under both 365 nm UV and solar irradiations. Sample with 12 mol% of Bi presented the best MB degradation activity; 310 min of solar irradiation allow 100% MB degradation, whereas only 62.49% MB degradation is achieved under UV irradiation. Our results suggest that codoping the persistent phosphors with Bi 3+ can be an alternative to enhance their photocatalytic activity.