光致发光
量子产额
发光
纳米点
光化学
化学
纳米材料
X射线光电子能谱
碳纤维
材料科学
荧光
分析化学(期刊)
纳米技术
化学工程
有机化学
光电子学
复合材料
工程类
物理
复合数
量子力学
作者
Till Thomas Meiling,Robin Schürmann,Stefanie N. Vogel,Kenny Ebel,Christophe Nicolas,Aleksandar R. Milosavljević,Ilko Bald
标识
DOI:10.1021/acs.jpcc.8b00748
摘要
Fluorescent carbon nanodots (CNDs) are very promising nanomaterials for a broad range of applications because of their high photostability, presumed selective luminescence, and low cost at which they can be produced. In this respect, CNDs are superior to well-established semiconductor quantum dots and organic dyes. However, reported synthesis protocols for CNDs typically lead to low photoluminescence quantum yield (PLQY) and low reproducibility, resulting in a poor understanding of the CND chemistry and photophysics. Here, we report a one-step synthesis of nitrogen-doped carbon nanodots (N-CNDs) from various carboxylic acids, Tris, and ethylenediaminetetraacetic acid resulting in high PLQY of up to 90%. The reaction conditions in terms of starting materials, temperature, and reaction time are carefully optimized and their influence on the photophysical properties is characterized. We find that citric acid-derived N-CNDs can result in a very high PLQY of 90%, but they do not show selective luminescence. By contrast, acetic acid-derived N-CNDs show selective luminescence but a PLQY of 50%. The chemical composition of the surface and core of these two selected N-CND types is characterized among others by high-resolution synchrotron X-ray photoelectron spectroscopy using single isolated N-CND clusters. The results indicate that photoexcitation occurs in the N-CND core, whereas the emission properties are determined by the N-CND surface groups.
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