Preparation And Application Study On Polymer Modified Graphene Quantum Dots

Energy shortage and environmental pollution are major problems worldwide. Brings to the environment problems in the process of energy utilization far-reaching effects on human society. Governments are already in new energy sources such as solar energy, wind energy, hydrogen invested enormous human and financial resources in the study, with its can be in clean energy and environmental pollution control can achieve organic combination, in order to reduce the environmental pollution and improve the efficiency of social production, the development of human long-term has far-reaching practical significance. As a newly developed energy source, solar energy is abundant, renewable, and pollution-free. Functional materials, metallic quantum dots in UV light because of its unique structure showed excellent catalytic performance and caused the extensive research, how to expand its application to the visible light range is a hot spot in the present study. However, insufficient research has been performed to synthesize graphene quantum dots(GQDs) with an excitation-independent behavior for the visible light photocatalytic degradation of organic matter. GQDs are new types of quantum dots, its excellent optical properties and potential application of biological cause the attention of the researchers, whether it has visible light photocatalytic properties and the biological imaging applications, making it both photocatalytic degradation of organic matter in water, and at the same time, the microorganisms in the water pollution can be targeted governance.This work focuses on the photocatalytic property of GQDs and polymer-modified GQDs under visible light. A hydrothermal synthesis route to GQDs was developed by using citric acid as a carbon precursor. The GQDs were modified with polyethylenimine(PEI) and polyethylene glycol(PEG). The obtained GQDs, GQDs-PEIs, and GQDs-PEGs were characterized and their structural information was determined through Fourier transform infrared spectroscopy(FTIR), transmission electron microscopy(TEM), photoluminescence spectroscopy, and UV-Vis absorption spectroscopy. Results revealed that the GQDs were uniform in size(2–5 nm) and rich in oxygen-containing groups. The GQDs exhibited a strong blue and excitation-independent photoluminescent behavior under excitation wavelengths of 320–420 nm.GQDs, GQDs-PEIs and GQDs-PEGs of potential applications in biology was studied, including biological compatibility and biological imaging application. Cytotoxicity test results show that the sample concentration in the range of 0-200 mu g/ml concentration, cell survival rate is over 67%, indirect GQDs, GQDs-PEIs, GQDs-PEGs for small cell toxicity; Compared three samples, in each sample concentrations, cell survival rate of GQDs, GQDs-PEGs, GQDs-PEIs reduced successively. In biological imaging, GQDs, GQDs-PEIs, GQDs-PEGs and MG-63 cells incubated with the common after 6 hours, all can enter into the cells.At the same time, the photocatalytic performance of these samples was demonstrated on the basis of methylene blue(MB) degradation. The photocatalytic rates of GQDs, GQDs-PEIs, and GQDs-PEGs decreased successively. The polymer-modified GQDs could qualitatively control the degradation rate of MB. Free radical species were generated to oxidize MB under light irradiation.Thus, photocatalytic organic matter degradation, sustained drug release, and tracking can be combined to implement proper sewage disposal.