Photoluminescent Carbon dots: synthesis, properties and applications

This presentation will focus on the evolution and recent developments of a new class of photoluminescent materials referred to as Carbon dots or C-dots, primarily comprising C, H, O, and N. Typically, C-dots have spherical shape with sizes lower than 20 nm, and can be synthesized at a large scale following the simple pyrolysis treatment of suitable carbon-rich precursors, including crude biomass, renewable resources, polymers, and carbon fibres (1,2). Depending on the preparation method and the nature of the starting materials, the graphitization degree, elemental composition and the morphology of C-dots can vary considerably, while post-synthesis treatments (such as chemical and electrochemical reactions, passivation strategies and physio-absorption) can modify their surface characteristics, thereby enhancing their solubility, biocompatibility, toxicity and optical properties (3).

In principle, C-dots demonstrate excitation wavelength-dependent emission with high quantum yields with the strongest emissions falling within the blue/green area, although red-emissive systems have also been reported (4). Moreover, the significant role of the organic fluorophores generated during the pyrolytic synthesis of C-dots has been demonstrated (5). Interest lies in the optical properties of C-dot-based aqueous dispersions, solid-state materials, polymer nanocomposites and nanopowders. This presentation will provide an overview of the structure--property relationships of C-dots with emphasis on emerging applications such as bioimaging, phototherapy, controlled drug release, molecular sensing, antimicrobial treatments, fertilisers, catalysis, energy conversion, nanoforensics, water treatment, environmental decontamination and anti-counterfeiting (6,7).

References

1. Stachowska, J.D.; Murphy, A.; Fernandes, D.; Gibbons, E.N.; Krysmann, M.J.; Kelarakis, A.; Burgaz, E.; Moore, J.; Yeates, S.G. Sci. Rep. 2021, 11, 10554
2. Krysmann, M.J.; Kelarakis, A.; Giannelis, E.P. Green Chem. 2012, 14, 3141
3.Kelarakis, A. Curr. Opin. Colloid Interface Sci. 2015, 20, 354
4.Gavalas, S.; Kelarakis, A. Nanomaterials 2021, 11, 2089
5. Krysmann, M.J.; Kelarakis, A.; Dallas, P.; Giannelis, E.P. J. Am. Chem. Soc. 2011, 134, 747
6. Fernandes, D.; Krysmann, M.J.; Kelarakis, A. Chem. Commun. 2015, 51, 4902
7.Verhagen, A.; Kelarakis, A. Nanomaterials 2020, 10, 1535