Fig. 4From: Highly sensitive and selective visual detection of Cr(VI) ions based on etching of silver-coated gold nanorodsUV–vis absorption spectra of Au NRs coated with Ag nanoshell of different thickness resulting from adding the different amounts of silver nitrate. The absorption spectra of various concentrations of Cr(VI): a from 10 μM to 60 μM in AuNR@Ag-1 (Au NRs coated with 350 μL of 0.01 M AgNO3), b from 5 μM to 35 μM in AuNR@Ag-2 (Au NRs coated with 250 μL of 0.01 M AgNO3), c from 2 μM to 12 μM in AuNR@Ag-3 (Au NRs coated with 150 μL of 0.01 M AgNO3) (Insets: photograph of color change of the AuNR@Ag colloid solutions upon the addition of Cr(VI) with different concentrations). d A graph of three distinctive measurement ranges of three nanoparticles with different Ag shell thicknesses (a) AuNR@Ag-1 (b) AuNR@Ag-2 and (c) AuNR@Ag-3. Data of less than 1% change rate were excludedBack to article page