Dual-emission carbon dots-stabilized copper nanoclusters for ratiometric and visual detection of CrO ions and Cd ions.

The pollution of heavy metal increases greatly accompanying by the development of industries. So, it is very important to build up a quick and reliable technique for detection of heavy metal ions. In this work, we developed a simple and convenient method for ratiometric and visual detection of CrO ions and Cd ions. We utilized glutathione as raw material to prepare cyan-emitting carbon dots (GSH@CDs). The GSH@CDs were further used as the template to prepare carbon dots-stabilized copper nanoclusters (GSH@CDs-Cu NCs) that displayed two well-separated emission peaks respectively at 450 nm and 750 nm. The GSH@CDs-Cu NCs can be applied for the ratiometric and visual detection of CrO and Cd ions based on the fluorescence quenching or enhancement of GSH@CDs-Cu NCs at 750 nm. A linear range of 2-40 μmol L with a detection limit of 0.9 μmol L for CrO ions, and a linear range of 0-20 μmol L with a detection limit of 0.6 μmol L for Cd ions were achieved based on this method. The fluorescent test strips for CrO ions were successfully prepared based on GSH@CDs-Cu NCs. Moreover, the GSH@CDs-Cu NCs were successfully applied to determine CrO and Cd ions in real samples with promising results.