Oil-Dispersible Green Emitting Carbon Dots: New Insights on a Facile and Efficient Synthesis

Gianluca Minervini^a^,^b, Annamaria Panniello^c, Elisabetta Fanizza^a^,^c, Maria Lucia Curri^a^,^b^,^c, Marinella Striccoli^c

^aDipartimento di Chimica, Università degli Studi di Bari,, Via Orabona 4, 70126 Bari, Italy

^bItalian National Interuniversity Consortium of Materials Science and Technology (INSTM)

^cCNR-IPCF Division of Bari, c/o Department of Chemistry, via Orabona 4, 70126 Bari, Italy

Proceedings of Internet Conference for Quantum Dots (iCQD)

Online, Spain, 2020 July 14th - 17th

Organizers: Quinten Akkerman, Raffaella Buonsanti, Zeger Hens and Maksym Kovalenko

Poster, Gianluca Minervini, 085
Publication date: 3rd July 2020

ePoster:

Carbon dots (CDs) are progressively attracting interest as novel environmentally friendly and cost effective luminescent nanoparticles for implementation in light-emitting devices, solar cells, photocatalytic devices and biosensors. [1] Here, starting from a cost effective bottom-up synthetic approach, based on a suitable amphiphilic molecule as carbon precursor, namely cetylpyridinium chloride (CPC), green-emitting CDs have been prepared in ambient conditions, upon treatment of CPC with concentrated NaOH solutions. The investigated method allows obtaining, in a one-pot procedure, both water-dispersible CDs (W-CDs) and oil-dispersible CDs (O-CDs), emitting in the green-yellow region of the visible spectrum, being the O-CDs characterized by a higher photoluminescence quantum-yield (PLQY). [2] The study provides original insights on the chemical reactions involved in the unique/distinctive process of carbonization of CPC in ambient conditions, finally proposing a reliable mechanism that accounts for the formation of the O-CDs in an aqueous system. In particular, the formation of intermediate blue-emitting molecular fluorophores during the CPC carbonization process and their contribution to the overall PL emission of the O-CDs are highlighted. The ability to discriminate the different species contributions allows to properly single out the O-CDs emission. Moreover, the preparative conditions have been investigated in order to further increase the efficiency of the synthetic approach, towards a fast preparation of brightly green-emitting CDs dispersible in various common organic solvents. In particular, a mild heating of the reaction mixture, at 70°C, has been demonstrated able to dramatically decrease the very long reaction time (i.e. from tens of hours to days, depending on the concentration of the added NaOH solution) required to obtain the O-CDs at room temperature, allowing to obtaining O-CDs in only 20 min, preserving their morphological and optical properties.

References:

[1] Sciortino, A., Cannizzo, A., Messina, F. Carbon Nanodots: A Review—From the Current Understanding of the Fundamental Photophysics to the Full Control of the Optical Response. C 2018, 4, 67.

[2] Zheng, B.; Liu, T.; Paau, M. C.; Wang, M.; Liu, Y.; Liu, L.; Wu, C.; Du, J.; Xiao, D.; Choi, M. M. F. One Pot Selective Synthesis of Water and Organic Soluble Carbon Dots with Green Fluorescence Emission. RSC Adv. 2015, 5, 11667–11675.

Acknowledgements:

This work has been financially supported by the Italian MIUR PRIN 2017 Candl2 Project Prot. n. 2017W75RAE. Italian National Interuniversity Consortium of Materials Science and Technology (INSTM) is also gratefully acknowledged.

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