Optical Properties Of Carbon Quantum Dots Prepared Hydrothermal Method

Carbon quantum dots(CQDs)is a new fluorescent carbon nano-material with many excellent properties.It has bright fluorescent good light/chemical stability,anti-bleaching characters,and good biocompatibility.It can be controlied the fluorescent emission wavelength of CQDs by tuning a variety of parameters,Therefore,CQDs has a seductive application prospects and deVelopment potential in the biological imaging,chemical sensing,drug delivery,optoelectronic deVices,solar cells and other areas.In this paper,glucose/fruit juice were used as carbon sources to synthesize CQDs by microwave-assisted hydrothermal It was tried to use fresh fruit juice as a carbon source to synthesize CQDs by hydrothermal reaction at high-pressure.The characterization and analysis of the structural morphology and optical properties of the prepared CQDs were carried out by TEM,XPS,XRD,PL and UV-vis absorption spectra.The main results and findings were as follows:1.The glucose was used as the carbon source and heated in the microwave oven with power of 700 W for 6.5-13.5 min to synthesize CQDs by microwave-assisted hydrothermal reactioa We got the carbon quantum dots with the size distribution of 2?5 nm.The synthesized CQDs disperse well and distribute eVenly,and their surface and edges contain a large amount of oxygen-containing groups such as-C=O,-O-C=O,-OH,and-COOH which can be stably present in aqueous solution.The CQDs will emit luminescence with the peak wavelength range of 492-628 nm excied by the light of 320-570 nm.2.It was found that two kinds of methods can be use for tuning luminescence wavelengths of CQDs under the same synthesis conditions:with the increasing of microwave heating time or the concentration of carbon source glucose solution,the carbonization degree of CQDs increases gradually,the fluorescence emission wavelength redshifts accordingly.3.The surface state and the type of carbon dots have a significant effect on the photo luminescence properties.The emission wavelength of the carbon dots has changed obviously,with ammonia concentration changes.4.Carbon quantum dots were obtained by hydrothermal reaction in the high pressure reactor,and their size distributions were 2.5?6 nm and 3?5.5 nm using lemon juice or orange juice as a carbon source,respectively,and have the good dispersion and the high crystallinity.CQDs prepared from lemon juice emit bright blue-color fluorescence excied by UV light of 365 nm...