Abstract
The carbon quantum dots (CQDs) were prepared by using an easy and economic one – pot method. The starting materials are the ascorbic acid as a carbon source and copper acetate as a catalyst to accelerate the reaction. The structural and optical properties of the CQDs are studied by UV-VIS spectrophotometer and photoluminescence (PL) measurements, transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FTIR). The excitation wavelength and the pH-dependent of PL properties was investigated also. The results show that the CQDs have strong absorption peak in the UV-region. The PL is the excitation wavelength dependent. The PL of CQDs decreases upon lowering the pH value of the solutions and the PL peaks shifted to the shorter wavelength. The average size of the CQDs is 4 nm from the TEM measurements.
Highlights
In recent years, the scientific and industrial committee show a great interest in the carbon nanomaterials due to their unique properties and applications, such that, photocatalysis, optoelectronic devices[1], sensors, security, and bioimaging, etc. [2]
It’s discovered by chance during the purification of carbon nanotubes in the electrophoresis method in 2004 [6]. It structure consists of a nanocrystalline core of the graphitic SP2hybridized, with functional groups on the surface. These functional groups are vary according to the raw materials which are used in the synthetic procedures [7].The carbon quantum dots (CQDs) have attracted much the attention from researchers due to: First of all, being of their eco-friendly, high biocompatible, chemically stable, low toxicity and highly soluble in water [8,9]
The main peaks are: The band of OH stretching vibration at 3392.79 cm-1, and 3410.15 cm-1, C-H at 2899.01 cm-1 and 2978.09 cm-1,C=O at 1558.48 cm-1 and 1631.78 cm-1, C-O-C at 1398.39 cm-1, C=C at 1558.48 cm-1 and 1631.78 cm-1. This result indicates that the CQDs are composed of a core and surrounded by effective surface groups such as hydroxyl, carboxyl, and alkyl [27]
Summary
The scientific and industrial committee show a great interest in the carbon nanomaterials due to their unique properties and applications, such that, photocatalysis, optoelectronic devices[1], sensors, security, and bioimaging, etc. [2]. The CQDs are characterized by the electronic and optical properties such as electron acceptor or donor, high photoluminescence, that have made it an important material in applications ,electronic, optical and sensing devices, bioimage, delivery of drug[10,11,12,13,14].the CQDs can be prepared using fast, low-cost method, and by from like natural raw materials or organic waste [15,16]. The optical and structural properties have been studied by using, FTIR, XRD, UV-VIS-NIR and TEM techniques
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