Synthesis And Characterization Of Blue And Green Fluorescent Carbon Dots And Their Application In Photocatalytic Degradation

Untill now, the preparation and application of carbon dots(C-dots) have attractted more and more people’s attention. The main reasons are as follows:1)its small molecular weight and particle size, strong penetrating power and low toxicity making them suitable for implementing within cell markers. 2) With UV light excitating a long time, its fluorescence properties was almost unchanged. So it has excellent performance and stable fluorescent properties. 3) When C-dots in light excitation, it was an excellent electron donor and acceptor, showing the nature of the light-induced electron transfer.In the present study, blue and green fluorescent C-dots were successfully synthesized by a facile one-pot heating method. Then we studied their potential application in photocatalytic degradation of organic dyes. It provides a new choice and idea for the design and study of the catalytic mechanism of the photocatalyst.The main research content and conclusions are as follows:1、The blue C-dots were synthesized by a facile one-pot hydrothermal method using glucose as the carbon source and L-cysteine as a modifier.The structure, morphology, fluorescence properties and surface groups of the C-dots were characterized by using XRD, TEM, FL, UV-vis absorption, FTIR spectra. In the experiment, the effects of the reaction temperature, reaction time, the amount of L-cysteine on the fluorescence properties were studied. Besides, the effects of the p H value, Na+, Cu2+ on the photo-luminescence properties of C-dots were also analyzed. The results indicated that C-dots has a characteristic peak of amorphous structure carbon; The size of prepared CDs is about 12.5 nm; Oxygen-containing hydroxyl and carboxyl groups were introduced into the surface of C-dots, enhancing its water-soluble; The nanoparticles not only have exhibit excitation wavelength dependence, but also has good light stability. The CDs have a quantum yield of about 5.2%. With the influence of a higher concentration of Na Cl solution, it has excellent salt tolerance. But in certain coexistence of Cu2+, the fluorescence intensity of C-dots has been significantly decreased.C-dots as a photocatalyst, its influence on the photocatalytic degradation of methyl green(MG) with sunlight simulating were studied.The effects of illumination time, the catalyst system, the concentration of MG and catalyst on the degradation were studied. The results indicated that:In the presence of H2O2, C-dots played a good role on the photocatalytic degradation of MG. When the methyl green was 40mg/L, adding 2ml nanoparticles, the degradation rate of Methyl Green was greater than 90% in three hours.2、The green fluorescence C-dots were synthesized by a facile one-pot solvothermal method using ascorbic acid and glycine as carbon source in ethanol and phosphoric acid medium.The structure, morphology, optical properties and surface groups of the prepared C-dots were characterized by using XRD, TEM, FL, UV-vis absorption and FTIR spectroscopy. In the experiment, the effects of the reaction temperature and time, the amount of glycine on the fluorescence properties have been studied. Besides, the effects of the p H value, Na+, Cu2+ on the photo-luminescence properties of C-dots were explored. The results indicated that:C-dots has a characteristic peak of carbon,s amorphous; The CDs have size of about 9.8nm; The hydroxyl and carboxyl groups were introduced into the C-dots surface, so its water solubility has been enhanced; The nanoparticles not only have exhibit excitation wavelength dependence, but also have good light stability,the CDs have a quantum yield of about 8.3%. With the influence of a higher concentration of Na Cl solution, the fluorescence intensity changed a little, that has excellent salt tolerance, but in certain coexistence of Cu2+, the fluorescence intensity of C-dots has been significantly decreased.C-dots as a photocatalyst, its impact on the photocatalytic degradation of acid fuschin with sunlight simulating were studied. The effects of light, illumination time, the catalyst system, the initial concentration of acid fuschin and the amount of catalyst on the photocatalytic degradation were explored. The experimental results indicated that in the presence of H2O2, C-dots played a good role on acid fuschin degradation. The degradation rate of 98% was reached in one hour.