论文简介 |
In this paper, we developed a simple, rapid, selective and colorimetric method to detect iodide (I−)
by etching silver-coated gold nanobipyramids (Au NBs@Ag nanostructure) in the presence of Cu2+. The
detection is based on the reaction that Cu2+ could oxidize I− into I2, which sequentially etches the Ag shell
of Au NBs@Ag nanostructure. When the Ag coating is thick and the Au NBs are buried in Ag nanorods,
the decrease of the Ag shell thickness and aspect ratio results in the blue-shift and intensity decrease of
the longitudinal localized surface plasmon resonances (LSPR) peak. The blue-shift and intensity decrease
of the longitudinal LSPR peak have been employed to quantificationally detect the concentration of I−.
The linear range of the detection could be improved by increasing the concentration of Cu2+ and reaction
time. Under the optimized conditions, both the blue-shift and intensity decrease of the longitudinal LSPR
have linear correlation with the concentration of I− in the range of 1.0–15 M. When the Ag coating
is very thin, the etching of the Ag shell results in the red shift of the LSPR in the visible range, which
further leads to the color of the colloid change from blue to pink. The etching-induced color change of
the colloid also depends on the concentration of I−, which enables the visual detection of I−. Compared
with other techniques, this method could facilitate multi-model quantitative detection of I− without any
sophisticated instrument. Interference studies and real samples test show that I− could be specifically
detected in dried kelp using this bimetallic optical nanoprobe.
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