Shiding Miao

Synthesis and characterization of cadmium phosphide quantum dots emitting in the visible red to near-infrared.

The synthesis of high-quality cadmium phosphide quantum dots with emission wavelength maxima in the range from 1200 to approximately 760 nm are reported. The results demonstrate that the nucleation and growth linked with the optical properties can be controlled by the temperature, the growth time, and the addition of ligands such as oleylamine and trioctylphosphine. Photoelectrochemical investigations revealed that the cadmium phosphide QD-derivatized electrodes show an optical response and that photocurrents of several nanoamperes per square centimeter can be obtained upon illumination.

Ultrasmall SnO 2 Nanocrystals: Hot-bubbling Synthesis, Encapsulation in Carbon Layers and Applications in High Capacity Li-Ion Storage

Ultrasmall SnO2 nanocrystals as anode materials for lithium-ion batteries (LIBs) have been synthesized by bubbling an oxidizing gas into hot surfactant solutions containing Sn-oleate complexes. Annealing of the particles in N2 carbonifies the densely packed surface capping ligands resulting in carbon encapsulated SnO2 nanoparticles (SnO2/C). Carbon encapsulation can effectively buffer the volume changes during the lithiation/delithiation process. The assembled SnO2/C thus deliver extraordinarily high reversible capacity of 908u2005mA·h·g−1 at 0.5 C as well as excellent cycling performance in the LIBs. This method demonstrates the great potential of SnO2/C nanoparticles for the design of high power LIBs.

Synthesis of Monodisperse Cadmium Phosphide Nanoparticles Using ex-Situ Produced Phosphine

The synthesis of nanoparticles using a gas-liquid interfacial reaction, which for the first time is shown to result in highly monodisperse materials across a range of sizes, is presented. We demonstrate, using cadmium phosphide as the paradigm that this synthesis method can provide colloidal nanocrystals or quantum dots monodisperse enough so that for the first time multiple transitions in their absorbance spectra can be observed. Clear evidence is given that the resulting cadmium material is Cd(6)P(7) and not Cd(3)P(2), and a thorough investigation into the role of temperature and growth time and their effects on the optical properties has been conducted. This strategy can be extended to synthesize other relevant members of the binary component pnictide semiconducting family, and the chemistry of the pnictide compound formation using this synthetic methodology has been explained using the redox potential of the metals. The suitability of the resulting cadmium phosphide quantum dots for applications in light-emitting diodes (LEDs) has further been demonstrated.

High Efficiency Dye-sensitized Solar Cells Constructed with Composites of TiO2 and the Hot-bubbling Synthesized Ultra-Small SnO2 Nanocrystals

An efficient photo-anode for the dye-sensitized solar cells (DSSCs) should have features of high loading of dye molecules, favorable band alignments and good efficiency in electron transport. Herein, the 3.4u2009nm-sized SnO2 nanocrystals (NCs) of high crystallinity, synthesized via the hot-bubbling method, were incorporated with the commercial TiO2 (P25) particles to fabricate the photo-anodes. The optimal percentage of the doped SnO2 NCs was found at ~7.5% (SnO2/TiO2, w/w), and the fabricated DSSC delivers a power conversion efficiency up to 6.7%, which is 1.52 times of the P25 based DSSCs. The ultra-small SnO2 NCs offer three benefits, (1) the incorporation of SnO2 NCs enlarges surface areas of the photo-anode films, and higher dye-loading amounts were achieved; (2) the high charge mobility provided by SnO2 was confirmed to accelerate the electron transport, and the photo-electron recombination was suppressed by the highly-crystallized NCs; (3) the conduction band minimum (CBM) of the SnO2 NCs was uplifted due to the quantum size effects, and this was found to alleviate the decrement in the open-circuit voltage. This work highlights great contributions of the SnO2 NCs to the improvement of the photovoltaic performances in the DSSCs.

Emissive ZnO@Zn3P2 Nanocrystals: Synthesis, Optical, and Optoelectrochemical Properties

ZnO@Zn3 P2 quantum dots (QDs) are synthesized, with emission from yellow to red. Photoelectrochemical investigations reveal that the current and voltage of the QD-derivatized electrodes show a response upon illumination. A photocurrent of ca. 8 nA cm(-2) for a monolayer of ZnO@Zn3 P2 QDs deposited on indium tin oxide (ITO) electrode is recorded.

Encapsulated Cd3P2 quantum dots emitting from the visible to the near infrared for bio-labelling applications

Cd3P2 quantum dots (QDs) have been synthesized in both aqueous and high boiling point surfactant solutions via a gas-bubbling method. The synthesized QDs exhibit photoluminescent wavelengths spanning across the visible red to the near-infrared (NIR) spectral region. Two types of shell materials, SiO2 nano-beads and PS micro-spheres, have been employed to encapsulate the Cd3P2 QDs which provide protecting layers against physiological solutions. The coating layers are proven to enhance the optical and chemical stability of Cd3P2 QDs, and make the fluorescent particles capable of sustaining long-term photo-oxidation. To demonstrate the applicability of the bio-labelling, the fluorescent composite particles (PS@QDs, SiO2@QDs) were injected into a culture medium of colorectal carcinoma (LoVo) cells. The results demonstrated that the PS@QDs exhibited a brighter fluorescence, but the SiO2@QDs provided a better photo-stability which consequently led to long-term cancer cell detection as well as a much lower release of toxic Cd2+ into the PBS solutions.

Overlapping double potential wells in a single optical microtube cavity with vernier-scale-like tuning effect

Spatially and temporally overlapping double potential wells are realized in a hybrid optical microtube cavity due to the coexistence of an aggregate of luminescent quantum dots embedded in the tube wall and the cone-shaped tubes geometry. The double potential wells produce two independent sets of optical modes with different sets of mode numbers, indicating phase velocity separation for the modes overlapping at the same frequency. The overlapping mode position can be tuned by modifying the tube cavity, where these mode sets shift with different magnitudes, allowing for a vernier-scale-like tuning effect.

The use of nanocrystals with emission in the visible or near infrared and their applications for photonics and optoelectronics.

A general synthetic strategy for the synthesis of nanocrystals of both visible and near infrared emitting materials is introduced. Further, the potential for these materials to be employed in a wide variety of applications is discussed.