Development of a Spectral Method for Qualitative and Quantitative Determination of the Surface Group Composition of Carbon Dots

Abstract

The relevance of studying carbon dots (CDs) stems from their unique optical and chemical properties, which make them promising materials for applications in sensing, catalysis, and biomedicine. For the effective use of CDs, a comprehensive study of the composition and properties of their surface groups is required.

In this work, the composition of the functional surface groups of CDs synthesized by the hydrothermal method from citric acid and thiourea was investigated using potentiometric titration, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). Potentiometric titration made it possible to determine the acid-base properties of the CD surface and quantitatively evaluate the content of carboxyl, hydroxyl, and amide groups. The XPS method confirmed the elemental composition of the CD surface, including the presence of nitrogen and sulfur, due to the use of thiourea as a precursor. FTIR spectroscopy revealed the functional groups on the CD surface, such as C=O, C–O, N–H, and S–H. As a result of a comparative analysis of all three methods, good agreement was achieved in the qualitative and quantitative determination of CD surface groups.

The obtained results demonstrate that the combination of the mentioned methods allows for a detailed study of the composition and properties of CD surface groups, which is important for their further functionalization and application as sensors or catalysts.

This research was supported by the Russian Science Foundation, project № 22-12-00138-П, https://rscf.ru/project/22-12-00138/.

Speaker

Kirill Kozhushnyi
Lomonosov Moscow State University, Faculty of Physics, Moscow, Russia
Russia

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