Toward Uniform Optical Properties of Carbon Dots. (14th July 2020)

• Record Type: Journal Article
• Authors: Noun, Farah; Manioudakis, John; Naccache, Rafik
• Is Part Of: Particle and particle systems characterization. Volume 37:Number 8(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-07-14
• Subjects: carbon dots -- microwave synthesis -- optical properties -- purification; Particles -- Periodicals; 620.43
• DOI: 10.1002/ppsc.202000119
• Languages: English
• ISSNs: 0934-0866

Abstract

Abstract: Carbon dots possess versatile optical properties that have prompted their investigation in applications including photocatalysis, photovoltaics, imaging, and drug delivery, among others. However, the preparation of these nanodots is accompanied by the formation of fluorophores and intermediates, which can be difficult to separate. In the absence of thorough purification protocols, the reported optical properties are often heterogeneous, which hinders understanding of their physicochemical and optical properties and concrete application development. Here, two hydrophilic carbon dot systems starting with citric acid and diethylenetriamine are prepared. The impact of purification, including dialysis, ultrafiltration, and organic washes, on the properties of the dots is demonstrated. It is shown that monitoring the purification endpoint using near‐infrared, fluorescence, and absorbance spectroscopies is possible. Moreover, it is demonstrated that fluorescence quantum yields can be a reliable tool to determine the purification endpoint. This work shows that even carbon dots derived from the same chemical precursors can have different purification profiles and purification requirements. However, the developed approach can be used to determine the proper purification procedure and endpoint for any carbon dot system regardless of the starting materials. Finally, it is envisioned that this work can be easily extended toward the purification of other hydrophilic nanomaterials. Abstract : Insufficient purification of carbon dots can lead to heterogeneity in their reported properties, hindering application development. Monitoring the purification endpoint is possible by tracking changes in their physico‐optical properties using established spectroscopic techniques. This approach uncovers their inherent properties and can be extended to many hydrophilic nanoparticle systems.