Preparation Of Carbon Quantum Dots By Electrochemical Method And Its Application

Carbon quantum dots(CQDs),a new type of carbon materials,less than 10 nm in size,have a lot of excellent performance,such as superior solubility in water,chemical inertness,low toxicity,easy functionalization,resistance to photobleaching and good photostability,having attracted widespread attention as a rising star in nanocarbon family in recent years.CQDs produced from various synthetic strategies find their wide values in more and more fields,especially in biomedicine,optoeletronics,catalysis and sensors.Various methods including electrochemical(EC)methods have been reported for synthesis of CQDs.In this paper,we mainly studied two methods to fabricate CQDs and their applications in efficient cell imaging and specific ferric ion detection.Herein,solid-state CQDs were simply prepared by bottom-up EC carbonization of nitriles(e.g.acetonitrile)in the presence of ionic liquid [e.g.1-butyl-3-methylimidazolium hexafluorophosphate(BMIMPF6)],using carbon-free electrodes.Due to the positive charges of BMIM+ on the C-dots,the final products presented in a precipitate form on the cathode,and the unreacted nitrilesand BMIMPF6 can be easily removed by simple vacuum filtration.The as-prepared solid-state CQDs can be well dispersed in aqueous medium with excellent photoluminescence properties.For the second method,a simple and efficient bottom-up EC strategy was proposed for the generation of multifunctional nitrogen doped carbon quantum dots(N-CQDs)using amino acids(AAs)as the green precursors.Based on the three-electrode electrochemical/electroanalytical(ECA)system,not only water-dispersible N-CQDs with strong photoluminescence and stable electrochemiluminescent properties were obtained,one simple and direct-vision way was also developed for identifying the utmost QY point during one synthetic cycle of CQDs generation.The CQDs were characterized by a number of techniques.It turned out that the CQDs fabricated via the two methods exhibited uniform size and thickness,and also strong photoluminescence.