Structure Matters: Tailored Graphitization of Carbon Dots Enhances Photocatalytic Performance.

Abstract

The chemical structure and photoredox properties of carbon dots (<b>CDs</b>) are not yet fully understood. However, it has been reported that, by carefully choosing the starting materials and tuning their synthesis conditions, it is possible to obtain <b>CDs</b> with different chemical structures and therefore different photocatalytic performance. For this work, a family of different <b>CDs</b> was synthesized in Milli-Q water <i>via</i> a microwave-assisted protocol, using citric acid and urea as precursors. The syntheses were carried out at different times and temperatures to assess the impact of the synthetic parameters on the photocatalytic properties of the final materials. After extensive and accurate purification, the photocatalytic abilities of a selected subset of <b>CDs</b> were tested by performing a photocatalyzed atom transfer radical addition reaction. Among the tested <b>CDs</b>, the best performing ones were found to be those synthesized at the highest temperature, which were the most graphitic. A number of different characterization techniques were then used to evaluate the degree of graphitization of <b>CDs</b> and to elucidate the origin of their different photocatalytic performance.