Jinfeng Xia

Controlled Synthesis of ZnS Quantum Dots and ZnS Quantum Flakes with Graphene as a Template

Novel ZnS quantum dots (QDs) and ZnS quantum flakes (QFs) were successfully prepared with graphene nanosheets (GNs) as a special template, and two unique heterostructures of ZnS/GNs were also obtained. Due to the structure-directing template effect of GNs, the as-synthesized ZnS with different morphologies, dots or flakes, were uniformly distributed on the surface of GNs by controlling nucleation and growth. The two different heterostructures of ZnS/GNs exhibited obvious photovoltaic response, and ZnS/GN QFs-on-sheet heterostructures show higher photovoltage than that of ZnS/GN QDs-on-sheet.

Novel luminescent yttrium oxide nanosheets doped with Eu3+ and Tb3+

Novel single-layer rare-earth oxide nanosheets were obtained by the exfoliation of Y(1−X)REXOBr (RE = Eu/Tb) layer. First, the Br− ions in Y(1−X)REXOBr were exchanged by benzoate ions under microwave conditions. The interlayer benzoate can chelate RE ions in the oxide layer, and change the structure and luminescence properties of the new layer compound. Then, a colloid of yttrium oxide nanosheets was obtained in n-butanol after the ultrasonic treatment of the benzoate-inserted layer for 30 min. The size and thickness of the yttrium oxide nanosheets were ∼800 nm and 0.8 nm, as measured by transmission electron and atomic force microscopies, respectively. A transparent thin film of the yttrium oxide nanosheets on indium tin oxide glass was prepared by electrophoretic deposition. The thin film showed strong red or green emission upon UV-light excitation based on Eu3+ and Tb3+ ions, respectively.

Near-infrared-emitting colloidal Ag2S quantum dots excited by an 808 nm diode laser

Thioglycolic acid (TGA)-coated colloidal Ag2S quantum dots (QDs) emitting in the near-infrared (NIR) region upon excitation by an 808 nm diode laser were synthesized. The observed photoluminescence (PL) was attributed to the presence of ligand-modified Ag2S on the QD surfaces and could be easily controlled by a simple dilution process due to the concentration-dependent surface structure of the colloidal QDs. Upon dilution of the solution, the PL intensity initially increased before later decreasing, with a blueshift being observed in the PL spectra. These phenomena can be accounted for by the aggregation of QDs due to a decrease in the content of ligand-modified Ag2S on the QD surfaces upon dilution, which in turn affected the fluorescence resonance energy transfer (FRET), and re-emission of the surface energy level.

Enhanced fluorescence of europium-doped yttrium hydroxide nanosheets modified by 2-thenoyltrifluoroacetone

A novel luminescent inorganic/organic hybrid nanosheet [Y2(1−x)Eu2x(OH)5(TTA)n]+ was successfully synthesized. The photoluminescence of the hybrid nanosheet was significantly different from that of the unmodified nanosheet. The main charge transfer band Eu–O of the nanosheet was replaced by the more efficient π–π* electron transition band of the organic ligands in the hybrid. The emission bands of the 5D0–7F2 electric dipole transition in the hybrid were enhanced greatly. We also prepared a novel transparent thin film of the luminescent inorganic/organic hybrid on FTO glass by electrophoretic deposition. On being excited by ultraviolet radiation, the thin films show strong red emission.