Zhenguang Wang

Synthesis, optical properties and applications of light-emitting copper nanoclusters

Metal nanoclusters (NCs) containing a few to a few hundreds of atoms bridge the gap between nanoparticles and molecular compounds. The last decade evidenced impressive developments of noble metal NCs such as Au and Ag. Copper is an earth abundant, inexpensive metal from the same group of the periodic table, which is increasingly coming into focus for NC research. This review specifically addresses wet chemical synthesis methods, optical properties and some emerging applications of Cu NCs. As surface protecting templates/ligands play an important role in the stability and properties of Cu NCs, we classified the synthetic methods by the nature of the capping agents. The optical properties of Cu NCs are discussed from the point of view of the effects of the metal core, surface ligands and environment (solvents and aggregation) on the emission of the clusters. Applications of luminescent Cu NCs in biological imaging and light emitting devices are considered.

Carbon-Supported Nickel Selenide Hollow Nanowires as Advanced Anode Materials for Sodium-Ion Batteries

Carbon-supported nickel selenide (Ni0.85 Se/C) hollow nanowires are prepared from carbon-coated selenium nanowires via a self-templating hydrothermal method, by first dissolving selenium in the Se/C nanowires in hydrazine, allowing it to diffuse out of the carbon layer, and then reacting with nickel ions into Ni0.85 Se nanoplates on the outer surface of the carbon. Ni0.85 Se/C hollow nanowires are employed as anode materials for sodium-ion batteries, and their electrochemical performance is evaluated via the cyclic voltammetry and electrochemical impedance spectroscopy combined with ex situ X-ray photoelectron spectroscopy and X-ray diffraction measurements. It is found that Ni0.85 Se/C hollow nanowires exhibit greatly enhanced cycle stability and rate capability as compared to Ni0.85 Se nanoparticles, with a reversible capacity around 390 mA h g-1 (the theoretical capacity is 416 mA h g-1 ) at the rate of 0.2 C and 97% capacity retention after 100 cycles. When the current rate is raised to 5 C, they still deliver capacity of 219 mA h g-1 . The synthetic methodology introduced here is general and can easily be applied to building similar structures for other metal selenides in the future.

Light-permeable, photoluminescent microbatteries embedded in the color filter of a screen

The battery and the screen are the two components occupying the largest volume in many electronic devices. Integrating them together will eventually engender a great reduction of device size. The current study demonstrates a promising strategy towards ultimate-compact electronic devices. Herein, a photoluminescent microbattery with reasonable light-permeability and hazing ability is developed. This aqueous Zn–MnOx/polypyrrole based microbattery features a flat architecture with interdigitated electrodes and utilizes a photoluminescent gelatin based electrolyte by embedding colloidal CdTe quantum dots. Furthermore, borax is introduced into the electrolyte as an additive, which effectively prevents luminescence quenching of the quantum dots and simultaneously enhances the electrochemical performance of the microbattery. A high device energy density of 21 mW h cm−3 is obtained. One step further, a three-primary-color (red–green–blue, RGB) photoluminescent microbattery array is assembled, endowing the battery with the function of a color filter and realizing a battery-in-screen configuration.

A Building Brick Principle to Create Transparent Composite Films with Multicolor Emission and Self‐Healing Function

A cellulose paper is used impregnated with light-emitting CdTe nanocrystals and carbon dots, and filled with a polyurethane to fabricate uniform transparent composite films with bright photoluminescence of red (R), green (G), and blue (B) (RGB) colors. A building brick-like assembly method is introduced to realize RGB multicolor emission patterns from this composite material. By sectioning out individual pixels from monochrome-emissive composite sheets, the advantage of the self-healing properties of polyurethane is taken to arrange and weld them into a RGB patterned fabric by brief exposure to ethanol. This provides an approach to form single layer RGB light-emitting pixels, such as potentially required in the display applications, without the use of any lithographic or etching processing. The method can utilize a wide range of different solution-based kinds of light-emitting materials.