Colorimetric Differentiation of Multiple Oxidizing Anions Based on Two Core–Shell Au@Ag Nanoparticles with Different Morphologies as Array Recognition Elements

The efficient discrimination of oxidizing anions is of considerable importance in environmental monitoring. Here, for the first time, we have developed a simple and fast colorimetric sensor array for detection and identification of oxidizing anions, which takes advantage of the etching of the Ag shell of two core–shell [email protected] nanoparticles ( [email protected] nanospheres ( [email protected] NPs) and [email protected] nanocubes ( [email protected] NCs)) by oxidizing anions. The differential etching ability of various oxidizing anions to the Ag shell of the two [email protected] nanoparticles resulted in different absorbance and color change of the nanoparticles. Thus, employing [email protected] NPs and [email protected] NCs as the array’s receptors and the indicators, six oxidizing anions (i.e., BrO 3 –, Cr 2 O 7 2–, ClO 4 –, IO 3 –, IO 4 –, and MnO 4 – ) down to 10 nM could be identified from each other by their own colorimetric response patterns. Moreover, the complex mixtures of oxidizing anions could be well discriminated. Most importantly, the sensor array was successfully applied to the discrimination of oxidizing anions in river water and tap water samples.