Zengxing Zhang

3D Printable Graphene Composite

In human being’s history, both the Iron Age and Silicon Age thrived after a matured massive processing technology was developed. Graphene is the most recent superior material which could potentially initialize another new material Age. However, while being exploited to its full extent, conventional processing methods fail to provide a link to today’s personalization tide. New technology should be ushered in. Three-dimensional (3D) printing fills the missing linkage between graphene materials and the digital mainstream. Their alliance could generate additional stream to push the graphene revolution into a new phase. Here we demonstrate for the first time, a graphene composite, with a graphene loading up to 5.6 wt%, can be 3D printable into computer-designed models. The composite’s linear thermal coefficient is below 75 ppm·°C−1 from room temperature to its glass transition temperature (Tg), which is crucial to build minute thermal stress during the printing process.

Gate-Controlled BP–WSe2 Heterojunction Diode for Logic Rectifiers and Logic Optoelectronics

p-n junctions play an important role in modern semiconductor electronics and optoelectronics, and field-effect transistors are often used for logic circuits. Here, gate-controlled logic rectifiers and logic optoelectronic devices based on stacked black phosphorus (BP) and tungsten diselenide (WSe2 ) heterojunctions are reported. The gate-tunable ambipolar charge carriers in BP and WSe2 enable a flexible, dynamic, and wide modulation on the heterojunctions as isotype (p-p and n-n) and anisotype (p-n) diodes, which exhibit disparate rectifying and photovoltaic properties. Based on such characteristics, it is demonstrated that BP-WSe2 heterojunction diodes can be developed for high-performance logic rectifiers and logic optoelectronic devices. Logic optoelectronic devices can convert a light signal to an electric one by applied gate voltages. This work should be helpful to expand the applications of 2D crystals.

Solution-processed anchoring zinc oxide quantum dots on covalently modified graphene oxide

The combination of semiconductor quantum dots (QDs) and graphene or graphene oxide is attracting much attention due to its unique properties and potential applications for optoelectronics or photocatalysts. Here a solution process is reported to firmly anchor zinc oxide QDs on the surface of graphene oxide by a covalent method. The graphene oxide is obtained with a modified Hummers method and slightly reduced and modified with hydrosulfide groups. Zinc oxide QDs are ultrasonically mixed with the modified graphene oxide and then anchored on the surface due to the strong interaction of Zn–S bond. The mixture is analyzed with transmission electron microscopy, energy dispersive spectroscopy, and Raman spectroscopy in details. Further photoluminescence spectroscopy and photoelectrical characterizations exhibit that charge transfer happens between zinc oxide QDs and graphene oxide, indicating it should have potential applications for optoelectronics and photocatalysts.

All-Metal-Organic Framework-Derived Battery Materials on Carbon Nanotube Fibers for Wearable Energy-Storage Device

The ever-increasing demands for portable and wearable electronics continue to drive the development of high-performance fiber-shaped energy-storage devices. Metal-organic frameworks (MOFs) with well-tunable structures and large surface areas hold great potential as precursors and templates to form porous battery materials. However, to date, there are no available reports about fabrication of wearable energy-storage devices on the utilization of all-MOF-derived battery materials directly grown on current collectors. Here, MOF-derived NiZnCoP nanosheet arrays and spindle-like α-Fe2O3 on carbon nanotube fibers are successfully fabricated with impressive electrochemical performance. Furthermore, the resulting all-solid-state fiber-shape aqueous rechargeable batteries take advantage of large specific surface area and abundant reaction sites of well-designed MOF-derived electrode materials to yield a remarkable capacity of 0.092 mAh cm-2 and admirable energy density of 30.61 mWh cm-3, as well as superior mechanical flexibility. Thus, this research may open up exciting opportunities for the development of new-generation wearable aqueous rechargeable batteries.