石墨烯
量子点
拉曼光谱
傅里叶变换红外光谱
光化学
材料科学
量子产额
X射线光电子能谱
纳米材料
吸收(声学)
化学
荧光
纳米技术
化学工程
物理
工程类
量子力学
光学
复合材料
作者
Yingbin Hu,Christof Neumann,Lena Scholtz,Andrey Turchanin,Ute Resch‐Genger,Siegfried Eigler
出处
期刊:Nano Research
[Springer Nature]
日期:2022-09-02
卷期号:16 (1): 45-52
被引量:17
标识
DOI:10.1007/s12274-022-4752-1
摘要
Graphene quantum dots (GQDs) have attracted increasing attention due to their favorable optical properties and have been widely used, e.g., in the biomedical field. However, the properties related to the chemical structure of GQDs, resulting in solvent-dependent optical properties, still remain unclear. Herein, we present the synthesis of long-wavelength emitting GQDs with a size of about 3.6 nm via a solvothermal method using oxo-functionalized graphene (oxo-G) and p-phenylenediamine as precursors and their structural and surface chemical analysis by transmission electron and atomic force microscopy (TEM; AFM) as well as Fourier-transform infrared, Raman, and X-ray photoelectron spectroscopy (FTIR; Raman; XPS). Subsequently, the influence of solvent polarity and proticity on the optical properties of the as-prepared GQDs bearing −OH, −NH2, −COOH and pyridine surface groups was investigated. Based on the results of the absorption and fluorescence (FL) studies, a possible luminescence mechanism is proposed. The observed solvent-induced changes in the spectral position of the FL maximum, FL quantum yield, and FL decay kinetics in protic and aprotic solvents of low and high polarity are ascribed to a combination of polarity effects, intramolecular charge transfer (ICT) processes, and hydrogen bonding. Moreover, the potential of GQDs for the optical sensing of trace amount of water was assessed. The results of our systematic spectroscopic study will promote the rational design of GQDs and shed more light on the FL mechanism of carbon-based fluorescent nanomaterials.
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