Zhipan Zhang

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 ]

Graphene quantum dots: an emerging material for energy-related applications and beyond

In this perspective, we focus on a new type of quantum dots, graphene quantum dots (GQDs). Due to quantum confinement and edge effects, GQDs have presented extraordinary properties, attracting extensive attention from scientists in the fields of chemistry, physics, materials, biology, and other interdisciplinary sciences. Herein, we summarize the significant advances achieved by us and other groups in the past few years on both the experimental and theoretical fronts. Synthetic strategies, unique optical and electronic properties, and the promise of GQDs in energy-related devices, such as photovoltaic devices, fuel cells, and light-emitting diodes, are systematically discussed.

Atomically Thin Mesoporous Nanomesh of Graphitic C3N4 for High-Efficiency Photocatalytic Hydrogen Evolution

Delamination of layer materials into two-dimensional single-atom sheets has induced exceptional physical properties, including large surface area, ultrahigh intrinsic carrier mobility, pronounced changes in the energy band structure, and other properties. Here, atomically thin mesoporous nanomesh of graphitic carbon nitride (g-C3N4) is fabricated by solvothermal exfoliation of mesoporous g-C3N4 bulk made from thermal polymerization of freeze-drying assembled Dicyandiamide nanostructure precursor. With the unique structural advantages for aligned energy levels, electron transfer, light harvesting, and the richly available reaction sites, the as-prepared monolayer of mesoporous g-C3N4 nanomesh exhibits a superior photocatalytic hydrogen evolution rate of 8510 μmol h(-1) g(-1) under λ > 420 nm and an apparent quantum efficiency of 5.1% at 420 nm, the highest of all the metal-free g-C3N4 nanosheets photocatalysts.

Graphitic Carbon Nitride Nanoribbons: Graphene‐Assisted Formation and Synergic Function for Highly Efficient Hydrogen Evolution

The development of new promising metal-free catalysts is of great significance for the electrocatalytic hydrogen evolution reaction (HER). Herein, a rationally assembled three-dimensional (3D) architecture of 1D graphitic carbon nitride (g-C3N4) nanoribbons with 2D graphene sheets has been developed by a one-step hydrothermal method. Because of the multipathway of charge and mass transport, the hierarchically structured g-C3N4 nanoribbon-graphene hybrids lead to a high electrocatalytic ability for HER with a Tafel slope of 54 mV decade(-1), a low onset overpotential of 80 mV and overpotential of 207 mV to approach a current of 10 mA cm(-2), superior to those non-metal materials and well-developed metallic catalysts reported previously. This work presents a great advance for designing and developing highly efficient metal-free catalyst for hydrogen evolution.

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.

Tailored graphene systems for unconventional applications in energy conversion and storage devices

Graphene-based materials have shown great potential in various fields across physics, chemistry, biology, and electronics, due to their unique electronic properties, facile synthesis, and ease of functionalization. In this review, we summarize the significant advances in tailored graphene systems for the recently developed unconventional energy conversion and storage devices reported by our group and others, namely focused on their tunable and controllable preparation and remarkable applications in new types of supercapacitors, lithium ion batteries, photovoltaic cells, and other emerging generators. This featured article also highlights the working principles and outlines the problems hindering the practical applications of graphene-based materials in these energy-related devices. Future research trends towards new methodologies in the design and synthesis of graphene-based systems with unique properties for emerging energy storage and energy conversion devices are also proposed.

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.

Spinning fabrication of graphene/polypyrrole composite fibers for all-solid-state, flexible fibriform supercapacitors

We have developed a facile and straightforward approach for the continuous fabrication of graphene/polypyrrole (G/PPy) composite fibers via a wet-spinning strategy. The diameter of G/PPy fibers can be well-controlled in the range of about 15–80 μm. Furthermore, the fiber possesses high conductivity and mechanical flexibility, thus offering significant advantages as flexible, lightweight electrodes for an efficient fiber-based electrochemical supercapacitor. The all-solid-state fiber supercapacitor with H2SO4–polyvinyl alcohol (H2SO4–PVA) gel electrolyte has been demonstrated, which could be woven into a textile for wearable electronics.

Dimension-tailored functional graphene structures for energy conversion and storage

Functional graphene nanostructures of interesting physical and chemical properties have been attracting lots of research effort. In this feature article we focus on some of the recent work of dimension-tailed graphene contributed by us and others, and review the current trends in the tunable and controllable preparation of functionalized graphene architectures ranging from zero-dimensional quantum dots to three-dimensional networks. Additionally, recent progresses in applying these dimension-tailored graphene structures in energy conversion and storage are explicitly discussed, particularly in devices such as solar cells, actuators, fuel cells, supercapacitors, etc., presenting the great prospect of functional graphene structures in this dynamic research field.

Stimulus-responsive graphene systems towards actuator applications

The rise of graphene has triggered the fast increasing research upsurge in both controllable synthesis of graphene and unique applications associated with its miraculous properties. In particular, graphene-based smart devices that can automatically respond to external stimulations are among those attracting our most attention. In this featured article, we summarize some of the recent advances in stimulus-responsive graphene actuation systems contributed by us and others, and discuss the different roles that graphene plays in various actuation circumstances such as under electrical, chemical, photonic, thermal and other stimuli. Impressive progress including graphene-based robots is also presented, demonstrating the great prospects of graphene actuation systems in a wide range of applications including sensors, switches, artificial muscles, nano/micro electromechanical devices, etc.