Hydrothermal Approach for the Preparation of Blue‐Emitting Carbon Quantum Dots: An Insight into the Influence of the Reaction Parameters

The surface of carbon quantum dots (CDs) is rich in functionalities, which could be selectively post-derivatized to obtain smart materials for various advanced applications. In this context, the development of a robust synthesis processes for CD formation is a considerable challenge to guarantee the reproducibility of the properties and functionalities on their surface for successful post-derivatization. Thus, understanding the formation mechanism of CDs at the molecular level and its correlations with the reaction parameters is of paramount importance. Herein, we describe how two selected purification strategies and the reaction parameters influence the properties of CDs obtained through the hydrothermal method. We adopted a simplified approach employing small molecules that can be extracted from biomass/biowaste to develop a sustainable and scalable synthetic strategy for industrial applications. First, we studied the influence of the reaction parameters on the CD morphological, structural, and chemical properties. Then, we show how the reaction parameters, the temperature in particular, influence the formation of graphitic nitrogen oxide centers in CD honeycomb structure and their role in determining CDs color and stability. Finally, we concluded that low reaction temperatures cause an incomplete CD nucleation process while higher ones lead to more stable CDs, with reproducible properties and surface functionalities.