Hydrothermal synthesis of carbon dots from Irish seaweed and seaweed derivatives Karlijn Hertsig, Yungxiang Liu, Peter W. Dunne Trinity College Dublin, Ireland Due to the increase in global renewable energy generation and the need for reduction in greenhouse gas emissions we find ourselves in the energy transition of the century wherein the demand for green, sustainable energy materials is rising. Carbon dots are considered a new and green nanomaterial, applicable for energy generation technologies, including photovoltaics. In this research the potential of seaweed and seaweed derivatives as feedstock for the hydrothermal formation of carbon dots was explored. Hydrothermal conversion of local kelp and Irish moss and seaweed derivatives, led to the formation of fluorescent chemical species emitting blue photoluminescence under UV illumination. Photophysical analysis of UV-vis and Fluorescence spectroscopy of the fluorescent species confirmed photoluminescent behaviour expected and reported for carbon dots, at ex. wl 360 nm and em. wl 448 nm. Structural characterisation by TEM, XRD and NMR confirmed fluorescent amorphous carbon, confirming the presence of carbon nanodots in dispersion. The fluorescence of the carbon dots produced was concluded to originate from molecular fluorescence due to the complex conjugated aromatic structure and heteroatoms present in the carbon nanodots. Aggregation of the fluorescent content was observed by eye, DLS and TEM and is explained by instability and impurities in the sample. Overall, seaweed and seaweed derivatives are concluded to be a viable feedstock for hydrothermal synthesis of carbon dots. References
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