Wentai Wang

Graphene oxide membranes with tunable permeability due to embedded carbon dots

In this communication, we fabricated graphene oxide membranes with tunable permeation by embedding carbon nanodots of controllable sizes.

Carbon dots functionalized by organosilane with double-sided anchoring for nanomolar Hg2+ detection

Surface functional groups on carbon dots (CDs) play a critical role in defining their photoluminescence properties and functionalities. A new kind of organosilane-functionalized CDs (OS-CDs) were formed by a low temperature (150°C) solvothermal synthesis of citric acid in N-(β-aminoethyl)-γ-aminopropylmethyl-dimethoxysilane (AEAPMS). Uniquely, the as-synthesized OS-CDs have dual long chain functional groups with both NH2 and Si(OCH3)3 as terminal moieties. Double sided anchoring of AEAPMS on CDs occurs, facilitated by the water produced (and confined at the interface between CDs and solvent) when citric acid condenses into the carbon core. The resultant OS-CDs are multi-solvent dispersible, and more significantly, they exhibit excellent selectivity and sensitivity to Hg(2+) with a linear detection range of 0-50 nM and detection limit of 1.35 nM. The sensitivity and selectivity to Hg(2+) is preserved in highly complex fluids with a detection limit of 1.7 nM in spiked 1 M NaCl solution and a detection limit of 50 nM in municipal wastewater effluent. The results show that the OS-CDs synthesised by the solvothermal method in AEAPMS may be used as an effective Hg(2+) sensor in practical situations.

Advancement in materials for energy-saving lighting devices

This review provides a comprehensive account of energy efficient lighting devices, their working principles and the advancement of these materials as an underpinning to the development of technology. Particular attention has been given to solid state lighting devices and their applications since they have attracted the most interest and are the most promising. Solid state lighting devices including white light emitting diodes (LEDs), organic LEDs (OLEDs), quantum-dot LEDs (QLEDs) and carbon-dot LEDs (CLEDs) are promising energy efficient lighting sources for displays and general lighting. However there is no universal solution that will give better performance and efficiency for all types of applications. LEDs are replacing traditional lamps for both general lighting and display applications, whereas OLEDs are finding their own special applications in various areas. QLEDs and CLEDs have advantages such as high quantum yields, narrow emission spectra, tunable emission spectra and good stability over OLEDs, so applications for these devices are being extended to new types of lighting sources. There is a great deal of research on these materials and their processing technologies and the commercial viability of these technologies appears strong.

Thickness dependence of magnetic and transport properties in organic-CoFe discontinuous multilayers

Spin-dependent transport measurement in 3-hexadecyl pyrrole (3HDP) with a CoFe layer and the current-in-plane geometry is reported. Transport properties indicate the CoFe layers are discontinuous when their thicknesses are smaller than 6 nm. The temperature dependence of the conductance suggests that the transport mechanism is likely small polaron hopping. The observed positive magnetoresistance ratio at low temperature gives evidence of spin-conserving transport.

High performance heterojunction photocatalytic membranes formed by embedding Cu2O and TiO2 nanowires in reduced graphene oxide

A heterojunction photocatalytic membrane consisting of Cu2O and TiO2 nanowires between reduced graphene oxide (rGO) sheets was fabricated using a facile process from a colloidal suspension. The resultant membrane exhibits significantly enhanced activity in the UV-vis range, surpassing nanowire dispersions, owing to the heterojunction formation and concurrent electron and hole transfer on rGO sheets. The membrane also possesses increased permeability and photocorrosion resistance. Such a design and fabrication method of an rGO-facilitated heterojunction photocatalytic membrane can be extended to a broad range of energy and environmental applications.

Visible Light Driven photocatalyst BiVO4 for photocatalytic removal of NO

BiVO4 nanoparticles were synthesized through hydrothermal method, and characterized by XRD, SEM, FTIR and UV-Vis. The BiVO4 were pure monoclinic scheelite type, with particle size around 300-500nm and band gaps around 2.34-2.45ev. The photocatalytic activity was evaluated by oxidation of NO under visible light irradiation. The hydrothermal temperature of 200 °C induced the best photocatalytic activity due to the fine crystalline phase, flower-like morphology and the stronger visible light absorbance.