Synthesis of water-stable and highly luminescent graphite quantum dots

Dsouza, Slavia Deeksha and Buerkle, Marius and Alessi, Bruno and Brunet, Paul and Morelli, Alessio and Payam, Amir Farokh and Maguire, Paul and Mariotti, Davide and Svrcek, Vladimir (2023) Synthesis of water-stable and highly luminescent graphite quantum dots. Nanotechnology, 34 (50). 505601. ISSN 0957-4484 (https://doi.org/10.1088/1361-6528/acf7cc)

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Abstract

Highly stable and environmentally friendly nitrogen-doped graphite quantum dots consisting of ∼12 layers of graphene, average diameter of ∼7.3 nm, prepared by atmospheric pressure microplasma are reported to have blue emission due to surface states created by nitrogen doping (9 atomic%) and reaction with oxygen. The low-temperature synthesis method requires simple precursors in water, with no annealing or filtration, producing crystalline disc-shaped quantum dots with ∼68% photoluminescence emission quantum yield at 420 nm excitation and that have shown stability for more than one month after the synthesis. The nitrogen doping in the quantum dots mainly occurs in graphitic core as substituted type of doping (63–67 atomic%) and the amount of doping is sufficient to create emissive states without impacting the core structure. The optical and chemical properties do not undergo serious retardation even with re-dispersion suggesting easy applicability for cellular imaging or optoelectronics.