FUEL-RICH PREMIXED FLAME AS A REACTOR FOR BLUE, GREEN AND YELLOW CARBON DOTS SYNTHESIS

Due to their eco-compatibility, low toxicity and chemical stability, Carbon Dots (CDs) are actually considered attractive candidates for applications in the fields of imaging, replacing organic dyes, electronics, as semiconductors, or sensors. This work has identified a fuel-rich premixed ethylene flame as a bottom-up system for generating blue, green, and yellow CDs. Particulate matter (PM) was sampled in an ethylene/oxygen (C/O=1) flame, through thermophoretic sampling, in the soot inception (6mm) and in the aged soot (14mm) region. In both cases, PM was separated in organic carbon (OC), soluble in dichloromethane, and refractory organic carbon (ROC), soluble in N-methyl pyrrolidinone. Chromatographic, mass spectrometric and spectroscopic analysis have been carried out to investigate the features of these pyrogenic products. It was found that OC, coming from PM sampled at both heights of the flame, presents the same fluorescence emission in the blue wavelength region (420-500nm). Therefore, the two samples were grouped under the name: blue CDs. Whereas ROC samples, derived from PM sampled at low and high heights, fluoresce in the green (500-550 nm) and yellow wavelength region (550- 600nm), respectively, and were named green CDs and yellow CDs. Insights on their structure and fluorescence mechanisms, which make them appealing for applications as CDs, have been reported.