Gold‐Cluster‐Based Dual‐Emission Nanocomposite Film as Ratiometric Fluorescent Sensing Paper for Specific Metal Ion

Abstract

Abstract A dual‐emission ratiometric fluorescent sensing film for metal ion detection is designed. This dual‐emission film is successfully prepared from chitosan, graphitic carbon nitride (g‐C 3 N 4 ), and gold nanoclusters (Au NCs). Here, it is shown that the g‐C 3 N 4 not only serves as the fluorescence emission source, but also enhances the mechanical and thermal stability of the film. Meanwhile, the Au NCs are adsorbed on the surface of chitosan film by the electrostatic interaction. The as‐prepared dual‐emission film can selectively detect Cu 2+ , leading to the quench of red fluorescence of Au NCs, whereas the blue fluorescence from g‐C 3 N 4 persists. The ratio of the two fluorescence intensities depends on the Cu 2+ concentration and the fluorescence color changes from orange red to yellow, cyan, and finally to blue with increasing Cu 2+ concentration. Thus, the as‐prepared dual‐emission film can be worked as ratiometric sensing paper for Cu 2+ detection. Furthermore, the film shows high sensitivity and selectivity, with low limit of detection (LOD) (10 ppb). It is observed that this novel gold‐cluster‐based dual‐emission ratiometric fluorescent sensing paper is an easy and convenient way for detecting metal ions. It is believed that this research work have created another avenue for the detection of metal ions in the environment.