Huhu Cheng

Nitrogen-Doped Graphene Quantum Dots with Oxygen-Rich Functional Groups

Graphene quantum dots (GQDs) represent a new class of quantum dots with unique properties. Doping GQDs with heteroatoms provides an attractive means of effectively tuning their intrinsic properties and exploiting new phenomena for advanced device applications. Herein we report a simple electrochemical approach to luminescent and electrocatalytically active nitrogen-doped GQDs (N-GQDs) with oxygen-rich functional groups. Unlike their N-free counterparts, the newly produced N-GQDs with a N/C atomic ratio of ca. 4.3% emit blue luminescence and possess an electrocatalytic activity comparable to that of a commercially available Pt/C catalyst for the oxygen reduction reaction (ORR) in an alkaline medium. In addition to their use as metal-free ORR catalysts in fuel cells, the superior luminescence characteristic of N-GQDs allows them to be used for biomedical imaging and other optoelectronic applications.

All‐Graphene Core‐Sheath Microfibers for All‐Solid‐State, Stretchable Fibriform Supercapacitors and Wearable Electronic Textiles

Flexible graphene fi ber (GF) stands for a new type of fi ber of practical importance, which integrates such unique properties as high strength, electrical and thermal conductivities of individual graphene sheets into the useful, macroscopic ensembles. GFs possess the common characteristics of fi bers like the mechanical fl exibility for textiles, while maintaining the uniqueness such as low cost, light weight, and ease of functionalization in comparison with conventional carbon fi bers. [ 1–3 ] Due to the extraordinary challenge to assemble two-dimensional (2D) microcosmic graphene sheets with irregular size and shape into macroscopic fi brillar confi guration, however, the success in fabrication of neat graphene fi bers only comes true recently. [ 1–4 ]

A Versatile, Ultralight, Nitrogen‐Doped Graphene Framework

Graphene lite: a density of (2.1 ± 0.3) mg cm(-3), the lowest to date for a graphene framework architecture, is achieved by preparing an ultralight, N-doped, 3D graphene framework (see photo of a block of the material balancing on a dandelion). Its adsorption capacity for oils and organic solvents is much higher than that of the best carbonaceous sorbents, and it is a promising electrode material for supercapacitors (484 F g(-1)) and as a metal-free catalyst for the oxygen reduction reaction.

Highly compression-tolerant supercapacitor based on polypyrrole-mediated graphene foam electrodes.

Deformation-tolerant devices are vital for the development of high-tech electronics of unconventional forms. In this study, a highly compressible supercapacitor has been fabricated by using newly developed polypyrrole-mediated graphene foam as electrode. The assembled supercapacitor performs based on the unique and robust foam electrodes achieves superb compression tolerance without significant variation of capacitances under long-term compressive loading and unloading processes.

Facile Fabrication of Light, Flexible and Multifunctional Graphene Fibers

Macroscopic graphene fibers with strength comparable to carbon nanotube yarns have been fabricated with a facile dimensionally-confined hydrothermal strategy from low-cost, aqueous graphite oxide suspensions, which is shapable, weavable, and has a density of less than 1/7 conventional carbon fibers. In combination with the easy in situ and post-synthesis functionalization, the highly flexible graphene fibers can be woven into smart textiles.

Newly-Designed Complex Ternary Pt/PdCu Nanoboxes Anchored on Three-Dimensional Graphene Framework for Highly Efficient Ethanol Oxidation

Newly-designed ternary Pt/PdCu nanoboxes on three-dimensional graphene framework (Pt/PdCu/3DGF) have been fabricated via a dual solvothermal strategy. This structurally well-defined Pt/PdCu/3DGF system possesses an approximately 4-fold improvement in catalytic activity for ethanol oxidation in alkaline media over the commercial 20% Pt/C catalyst as normalized by the total mass of active metals, showing the great potential for direct fuel cell applications.

Textile electrodes woven by carbon nanotube–graphene hybrid fibers for flexible electrochemical capacitors

Functional graphene-based fibers are promising as new types of flexible building blocks for the construction of wearable architectures and devices. Unique one-dimensional (1D) carbon nanotubes (CNTs) and 2D graphene (CNT/G) hybrid fibers with a large surface area and high electrical conductivity have been achieved by pre-intercalating graphene fibers with Fe3O4 nanoparticles for subsequent CVD growth of CNTs. The CNT/G hybrid fibers can be further woven into textile electrodes for the construction of flexible supercapacitors with a high tolerance to the repeated bending cycles. Various other applications, such as catalysis, separation, and adsorption, can be envisioned for the CNT/G hybrid fibers.

Graphene Fibers with Predetermined Deformation as Moisture‐Triggered Actuators and Robots

Enough to make your hair curl! Moisture-responsive graphene (G) fibers can be prepared by the positioned laser reduction of graphene oxide (GO) counterparts. When exposed to moisture, the asymmetric G/GO fibers display complex, well-controlled motion/deformation in a predetermined manner. These fibers can function not only as a single-fiber walking robot under humidity alternation but also as a new platform for woven devices and smart textiles.

Moisture-activated torsional graphene-fiber motor.

A new type of moisture-driven rotational motor is developed using a helical arrangement of graphene sheets along a graphene oxide fiber, which not only presents remarkable performance as a reversible rotary motor with a rotary speed of up to about 5200 revolutions per minute under humidity alternation, but also allows the construction of humidity switches and promising moisture-triggered electric generators.

Graphene-Quantum-Dot Assembled Nanotubes: A New Platform for Efficient Raman Enhancement

Graphene quantum dots (GQDs), single or few-layer graphenes with a size of only several nanometers, are a new type of quantum dots (QDs) with unique properties. The assembly of QDs in a geometrically well-defined fashion opens up opportunities to obtain access to the full potential of assembled QDs by virtue of the collective properties of the ensembles. In the current study, we present the well-organized assembly of zero-dimensional (0D) functional GQDs into 1D nanotube (NT) arrays and demonstrate their remarkable potential as a new metal-free platform for efficient surface-enhanced Raman scattering (SERS) applications. The hierarchically porous 1D nanotube structure of 0D GQDs has been prepared by electrophoresis deposition within a nanoporous AAO template. On the basis of the unique porous nanotube architecture of GQDs, the GQD-NTs could ensure a more efficient charge transfer between the target molecules and the GQDs and thus produce much stronger SERS effect, exceeding that on flat graphene sheets. The unique architecture of 1D nanotubes of 0D GQDs provides a new point of view for designing and fabricating SERS substrates.