Solvent-Free Preparation of Tannic Acid Carbon Dots for Selective Detection of Ni(2+) in the Environment

Carbon dots (CDs) are widely used nanomaterials that not only exhibit good biocompatibility and photostability, but also benefit from a simple preparation process and easy functionalization, making them promising for broad applications in the fields of heavy metal ion detection and optoelectronic devices. Based on the excellent optical properties of CDs and the current situation of increasing energy shortages, this paper selects the natural polyphenolic compound tannic acid (TA) found in biomass materials as the carbon source and innovatively adopts a simple and convenient solvent-free pyrolysis method without auxiliary reagents or solvents. The CDs with good water solubility and certain fluorescence properties were directly prepared under the condition of high temperature, and the obtained CDs exhibited blue fluorescence, and a high QY of 35.4% was obtained at 300 °C. The analysis and results demonstrate the selectivity of these CDs for the detection of various metal ion solutions. In particular, these CDs are sensitive to Ni(2+) and can be used as fluorescent sensors for the efficient and sustainable detection of Ni(2+), whereas previous sensors were often specific to Fe(3+) and Hg(2+). Thus, a new sensing technique has been developed for the detection of Ni(2+) to achieve more sensitive and rapid detection.