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트란반탐,최원묵 한국물리학회 2018 Current Applied Physics Vol.18 No.11
In this work, a green and simple one-pot route was developed for the synthesis of highly fluorescent aminofunctionalized graphene quantum dots (a-GQDs) via hydrothermal process without any further modification or surface passivation. We synthesized the a-GQDs using glucose as the carbon source and ammonium as a functionalizing agent without the use of a strong acid, oxidant, or other toxic chemical reagent. The as-obtained a- GQDs have a uniform size of 3–4 nm, high contents of amino groups, and show a bright green emission with high quantum yield of 32.8%. Furthermore, the a-GQDs show effective fluorescence quenching for Cu2+ ions which can serve as effective fluorescent probe for the detection of Cu2+. The fluorescent probe using the obtained a- GQDs exhibits high sensitivity and selectivity toward Cu2+ with the limit of detection as low as 5.6 nM. The mechanism of the Cu2+ induced fluorescence quenching of a-GQDs can be attributed to the electron transfer by the formation of metal complex between Cu2+ and the amino groups on the surface of a-GQDs. These results suggest great potential for the simple and green synthesis of functionalized GQDs and a practical sensing platform for Cu2+ detection in environmental and biological applications.
Duong Van Thiet,NGUYENVAN QUANG,Nguyen Thi Minh Hai,Nguyen Thi Huong,조성래,Duong Anh Tuan,Dang Duc Dung,트란반탐 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.8
In this work, we report on the structural and thermoelectric properties of Sb2Te3 films deposited on GaSb(111) substrates by using molecular beam epitaxy. The effects of the growth temperature on the microstructure and thermoelectric properties of the films were investigated. The results show that Sb2Te3 films grow on GaSb(111) along (00l) axis normal to the substrate and have a hexagonal structure with a layer-by-layer growth mode in growth temperature range from 200 to 250 °C while at 175 and 300 °C, the films show an island growth mode. Te and Sb2Te3 phases coexist at a growth temperature of 175 °C. The films exhibit a metallic behavior for growth temperatures below 250 °C and a semiconductor behavior at 300 °C. By changing growth temperature, we were able to vary the carrier density from 9.96×1018 to 4.55×1019 cm −3. At room temperature, the Seebeck coefficients are 110, 146, and 138 μV/K for growth temperatures of 175, 200 and 250 °C, respectively, and a large value of the power factor 61.67 μW/cm-K2 is achieved for the film grown at 250 °C.