Yu Jingjing, Liu Chang, Yuan Kang, Lu Zunming, Cheng Yahui, Li Lanlan, Zhang Xinghua, Jin Peng, Meng Fanbin, Liu Hui
School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China.
Department of Electronics and Key Laboratory of Photo-Electronic Thin Film Devices and Technology of Tianjin, Nankai University, Tianjin 300071, China.
Nanomaterials (Basel). 2018 Apr 12;8(4):233. doi: 10.3390/nano8040233.
In this paper, spherical carbon dots (CDs) with distinct compositions and surface states have been successfully synthesized by a facile microwave method. From the fluorescence spectra, several characteristic luminescence features have been observed: surface amino groups are dominant in the whole emission spectra centering at 445 nm, and the fingerprint emissions relevant to the impurity levels formed by some groups related to C and N elements, including C-C/C=C (intrinsic C), C-N (graphitic N), N-containing heterocycles (pyridine N) and C=O groups, are located around 305 nm, 355 nm, 410 nm, and 500 nm, respectively. Those fine luminescence features could be ascribed to the electron transition among various trapping states within the band structure caused by different chemical bonds in carbon cores, or functional groups attached to the CDs' surfaces. According to the theoretical calculations and experimental results, a scheme of the band structure has been proposed to describe the positions of those trapping states within the band gap. Additionally, it has also been observed that the emission of CDs is sensitive to the concentration of Fe ions with a linear relation in the range of Fe concentration from 12.5 to 250 μM.
在本文中，通过简便的微波法成功合成了具有不同组成和表面状态的球形碳点。从荧光光谱中观察到了几个特征发光特性：表面氨基在以445 nm为中心的整个发射光谱中占主导地位，与由一些与C和N元素相关的基团形成的杂质能级相关的指纹发射，包括C-C/C=C（本征C）、C-N（石墨N）、含氮杂环（吡啶N）和C=O基团，分别位于305 nm、355 nm、410 nm和500 nm左右。这些精细的发光特性可归因于碳核中不同化学键或附着在碳点表面的官能团引起的能带结构内各种俘获态之间的电子跃迁。根据理论计算和实验结果，提出了一种能带结构方案来描述能带隙内那些俘获态的位置。此外，还观察到碳点的发射对Fe离子浓度敏感，在12.5至250 μM的Fe浓度范围内呈线性关系。
