Pulsed Laser Fragmented Carbon Black Powders for the Synthesis of Carbon Nanodots

Abstract

The pulsed laser fragmentation in liquid media of carbon black (CB) powders using picosecond (ps) laser pulses to produce photoluminescent carbon nanodots (CNDs) is reported. A 1064 nm Nd:YAG pulsed laser with a repetition rate of 15 Hz and 30 ps pulse duration was used. The fragmentation of CB agglomerates suspended in acetone, composed of 80 nm particles, was induced under 10, 20 and 30 min of fragmentation time to reach CNDs with 8 nm diameter average. The PL response of the CNDs solutions shown excitation-wavelength dependence, whose intensity was improved for all the excitation wavelengths with a post-synthesis irradiation by 10 min. The post-irradiation re-fragment the already suspended carbon dots, reaching stable, homogenized and CNDs solutions with similar PL features independently of the F-time. Time-resolved spectroscopy measurements allowed to identify the PL response is characterized by two-lifetime components of 3 ns and 0.15 ns. Raman analysis allowed to observe the D and G peaks characterizing the CNDs and raw material. The CNDs solution showed stable emission and well-dispersion after 9 months. CB is considered a waste material but is shown here as a suitable carbon source to produce CNDs for light emission using the PLFL pathway.