Preparation Of Grapheme Oxide-quantum Dots Composite And Its Application In The Copper Detection

Graphene, a single-atom-thick and two-dimensional sp2 carbon networking material, has excellent electrical and optical properties. The development of graphene-based hybrid nanostructures, in which different nanomaterials including quantum dots(QDs), gold nanoparticles, Ti O2 nanoparticles immobilized on graphene or graphene oxide sheet, has been expanded with various applications of solar cells sensors, photocatalysis and transistors.Semiconductor quantum dots have good quantum size effect, high fluorescence quantum yield, excitation spectrum width, narrow emission spectrum and can be used as the active layer in solar cell. Performance in QDs solar cells is stunted by limitations in sensitizer loading arising from losses inherent in the nature of electron transport throughout the quantum dot network. Electron conductance within QD films proceeds via electron hopping between orbitals on adjacent QDs, a process termed random walk and the process couled be affected by recombination or trapped-state. In particular, graphene's atomic thinness and large sheet surface area combined with excellent electron transport properties make it an ideal material for optimizing electron transport within QDs films while minimizing incident light absorption. When the graphene and quantum dot compound, photogenerated electrons can jump onto the graphene effective current to an electrode, and reduced the electrons in quantum dots recombination and trapped-state, which can effectively improve the energy conversion efficiency of solar cells. Therefore, we synthesized grapheme-QDs nanocomposites with the excellent broadband absorption capacity of quantum dots and excellent electrical properties of graphene, which coulde be applied in solar cell.Copper, widely distributed in nature, is also indispensable in many biological processes such as catalysis coenzyme, biosynthesis, biological transport. Organisms copper concentration level will affect the life activities of the organism, When the copper in the body is too low, many life activities can't be occurred, however when copper is too high, it will inhibit the activity of some enzymes or produces neurotoxicity in the human body. Common copper ion detection methods have spectrophotometric methods, electrochemical analysis, flouresence methods, chemiluminescence. Among them, flouresence methods have good selectivity and high sensitivity, attracted widespread attentions. Here, GO-DNA-Cd Te probe was prepared as bioflourescence sensor to detect copper ion.This thesis was financial supported from the National Natural Science Foundation of China(NO.50802069) and Natural Science Foundation of Hubei(NO. 2014CFB831). Graphene-Cd Te/Cd Te quantum dots composite, graphene oxide-DNA-Cd Te quantum dots probe have been synthesized and characterized the composites were applied in solar cells and copper detection, respectively. The main contents include:(1) Cd Te/Cd S core-shell quantum dots and Cd Te quantum dots were synthesized by the one-pot method and graphene oxide was prepared by improved Hummers method.(2) Graphene-Cd Te/Cd S quantum dots composite was prepared by hydrothermal methods. We optimized the synthesis conditions and studied the optical properties of the composite, and clarified optical properties of composites reinforced mechanisms.(3) GO-DNA-Cd Te fluorescent probes were prepared by chemical cross-linking method, which was applied to the detection of copper ion concentration, and DNA thermal stability and storage stability have been significantly improved, and clarify the fluorescent probe to detecte the copper ions.