One‐step Green Synthetic Approach for the Preparation of Orange Light Emitting Copper Nanoclusters for Sensitive Detection of Mercury(II) Ions

In this paper, we synthesized water‐soluble fluorescent Cu nanoclusters (Cu NCs) through simple reduction reaction with 2‐mercaptobenzimidazole as a protective agent, polyvinyl pyrrolidone (PVP) as a stabilizer and ascorbic acid as a reducing agent for the first time. The optical properties and structures of as‐prepared Cu NCs were characterized by fluorescence spectroscopy, UV‐vis, FT‐IR, TEM and XPS. The characterization results showed that the Cu NCs had better fluorescence intensity, high dispersion and large Stokes shift. The Cu NCs had excellent stability against photo‐illumination and ionic strength and displayed an excitation‐independent fluorescence characteristic. The as‐prepared Cu NCs was selectively and sensitively quenched by Hg2+. Furthermore, the fluorescence of Cu NCs was linearly quenched in the range of 2–40 μM (concentration of Hg2+) with a detection limit of 23.0 nM. More importantly, this prepared Cu NCs could be successfully utilized as a probe for detection of Hg2+ in real water samples. A rapid sonochemical route is used for green, fast, and large‐scale synthesis of highly fluorescent Cu nanoclusters for Hg2+ sensing. Meaningfully, the as‐prepared Cu NCs exhibited excellent water solubility, low cytotoxicity, good photostability and high stability toward high ionic strength. Importantly, the relative fluorescence intensity was linear with the Hg2+ concentrations range from 2 to 40 μM. The fluorescence probe was successfully employed for the detection of Hg2+ in real water samples.