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Optical pH Sensor with Rapid Response Based on a Fluorescein‐Intercalated Layered Double Hydroxide
Author(s) -
Shi Wenying,
He Shan,
Wei Min,
Evans David G.,
Duan Xue
Publication year - 2010
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201001081
Subject(s) - materials science , hydroxide , substrate (aquarium) , micrometer , indium tin oxide , analytical chemistry (journal) , fluorescence , luminescence , electrophoretic deposition , nanotechnology , optics , thin film , optoelectronics , chemical engineering , chromatography , chemistry , oceanography , physics , engineering , geology , coating
The preparation of a highly oriented photoluminescent film of fluorescein (FLU) and 1‐heptanesulfonic acid sodium (HES) co‐intercalated in a layered double hydroxide (LDH) matrix by electrophoretic deposition (EPD) is reported, and its application as an optical pH sensor is demonstrated. The FLU‐HES/LDH films with thickness ranging from nanometer to micrometer on indium tin oxide substrates exhibite good c ‐orientation of LDH platelets (the ab ‐plane of the LDH platelets parallel to the substrate), as confirmed by X‐ray diffraction and scanning electron microscopy. Polarized luminescence of the film is observed with anisotropy value r = 0.29, resulting from the highly oriented FLU in the LDH gallery. Furthermore, the optical pH sensor with film thickness of 300 nm exhibits a broad linear dynamic range for solution pH (5.02–8.54), good repeatability (relative standard deviation (RSD) less than 1.5% in 20 consecutive cycles) and reversibility (RSD less than 1.5% in 20 cycles), high photostability and storage stability (ca. 95.2% of its initial fluorescence intensity remains after one month) as well as fast response time (2 s). Therefore, this work creates new opportunities for the preparation and application of LDH‐based chromophores in the field of optical sensors.