Feghhi Fazeleh, Minagar Ava, Madaah Hosseini H R
epartment of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, P.O. Box 11155-9466, Tehran, Iran.
epartment of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, P.O. Box 11155-9466, Tehran, Iran; Institute for Convergence Science & Technology, Center for Bioscience & Technology, Sharif University of Technology, Tehran 1458889694, Iran.
J Colloid Interface Sci. 2023 Dec;651:36-46. doi: 10.1016/j.jcis.2023.07.157. Epub 2023 Jul 28.
Cysteine, as a non-aromatic precursor, was used to produce Nitrogen (N) and Sulfur (S) sources for preparing N, S-doped carbon dots (CDs) with tunable luminescence emission. Despite the tremendous investigations, the photoluminescence (PL) mechanism of CDs is still unclear due to its complex core-shell structure, variety of surface functional groups, and structure dependency. This study focuses on controlling aromatization and graphitization processes during the hydrothermal synthesis on CDs by using Citric Acid (CA) and Ammonium persulfate. Detailed characterizations by FTIR spectroscopy, XPS, and HR-TEM are provided to suggest both chemical and bandgap structures. Results reveal that the red-shift of PL occurred due to the graphitization and increasing content of graphitic nitrogen in the core, as well as the Pyridinic and Amine groups creating sub-bands on the surface. These findings resolve the controversy on the PL mechanism of Cysteine-based CDs and provide a general guide for increasing the aromatization and graphitization degree from non-aromatic precursors which clarify the mechanism exploration and structural analysis of other types of CDs.
半胱氨酸作为一种非芳香族前驱体，被用于制备具有可调发光发射的氮（N）和硫（S）掺杂碳点（CDs）的氮源和硫源。尽管已有大量研究，但由于碳点具有复杂的核壳结构、多样的表面官能团以及结构依赖性，其光致发光（PL）机制仍不明确。本研究聚焦于通过使用柠檬酸（CA）和过硫酸铵来控制碳点水热合成过程中的芳构化和石墨化过程。通过傅里叶变换红外光谱（FTIR）、X射线光电子能谱（XPS）和高分辨透射电子显微镜（HR-TEM）进行详细表征，以揭示其化学结构和带隙结构。结果表明，PL的红移是由于核内石墨化以及石墨氮含量增加，以及表面吡啶基和胺基形成子带所致。这些发现解决了基于半胱氨酸的碳点PL机制的争议，并为从非芳香族前驱体提高芳构化和石墨化程度提供了通用指导，这有助于阐明其他类型碳点的机制探索和结构分析。
