Preparation of photoluminescent carbon nanodots by traditional Chinese medicine and application as a probe for Hg2+

A friendly environmental and low-cost preparation of water-soluble photoluminescent carbon nanodots (C-Dots) utilizing the rhizome of the plant Giant Knotweed Rhizome, a traditional Chinese medicine, as a carbon source via hydrothermal method is developed for the first time. The as-prepared photoluminescent C-Dots show favorable blue color photoluminescence at the peak wavelength of 430 nm with a quantum yield of approximately 11.5%. It has been successfully applied as a novel probe for the detection of Hg2+. This novel probe exhibits excellent sensitivity and selectivity toward Hg2+ in the broad linear range from 50 nM to 100.0 mu M with a limit of detection as low as 8.2 nM. The practical use of this system was tested in river water by adding 10.0 mu M and 50.0 mu M Hg2+. The recoveries ranged from 101.0% to 104.0% and from 99.2% to 101.2%, respectively. These stable and economical photoluminescent C-Dots show promise as a powerful tool for environmental analysis.