ULTRAFINE AND STABLE FLUORESCENT C-DOTS AND DOPED C-DOTS FOR SUPERCAPACITOR AND BIOMEDICAL APPLICATIONS

Vijay Bhooshan Kumar ¹ Aharon Gedanken ^1,4 Zeev Porat ^2,3

¹Department of Chemistry, Institute for Nanotechnology and Advanced Materials, Bar-Ilan University
²Division of Chemistry, Nuclear Research Center Negev
³Institute of Applied Research, Ben-Gurion University of the Negev
⁴Department of Materials Science & Engineering, National Cheng Kung University

This research describes the one-step sonochemical synthesis of carbon dots (C-dots), which is carried out by sonication of pristine polyethylene glycol (PEG-400) for 0.5-3 hour. It demonstrates how various experimental parameters, such as the sonication time, the temperature and the amplitude of sonication affect the size of the C-dots (2-10 nm) and their fluorescence. The highest measured quantum yield of emission was ~16%. The synthesized C-dots were coated on polythene, Si-wafer and activated carbon (AC). C-dots were used for bio-imaging of living cells, whereas AC/C-dots were used as supercapacitors. Electrodes made of AC/C-dots demonstrated specific capacitance of 0.185 F.g^-1.cm^-2, almost 3 times higher than unmodified carbon. This electrode material also exhibited extremely stable galvanostatic performance over more than 5000 consecutive cycles with Coulombic efficiency around 100%.

In addition to that we synthesized C-dots doped with metals (Ga, In, Sn) and non-metals (N, P, S) for various applications, such as bio-imaging, antibacterial activity and gene delivery). We observed that the antibacterial activity of Ga@C-dots was high already with very low concentrations of Ga doping (ppb). N@C-dots was used for high-contrast bio-imaging of life cells, showing very high quantum yield (ca. 44%) and good biocompatibility.