Graphene has attracted tremendous research interest in recent years, owing to its exceptional properties. The scaled-up and reliable production of graphene derivatives, such as graphene oxide (GO) and reduced graphene oxide (rGO), offers a wide range of possibilities to synthesize graphene-based functional materials for various applications. This critical review presents and discusses the current development of graphene-based composites. After introduction of the synthesis methods for graphene and its derivatives as well as their properties, we focus on the description of various methods to synthesize graphene-based composites, especially those with functional polymers and inorganic nanostructures. Particular emphasis is placed on strategies for the optimization of composite properties. Lastly, the advantages of graphene-based composites in applications such as the Li-ion batteries, supercapacitors, fuel cells, photovoltaic devices, photocatalysis, as well as Raman enhancement are described (279 references).

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Graphene-based composites

Graphene based materials: Past, present and future

Graphene, a two-dimensional, single-layer sheet of sp(2) hybridized carbon atoms, has attracted tremendous attention and research interest, owing to its exceptional physical properties, such as high electronic conductivity, good thermal stability, and excellent mechanical strength. Other forms of graphene-related materials, including graphene oxide, reduced graphene oxide, and exfoliated graphite, have been reliably produced in large scale. The promising properties together with the ease of processibility and functionalization make graphene-based materials ideal candidates for incorporation into a variety of functional materials. Importantly, graphene and its derivatives have been explored in a wide range of applications, such as electronic and photonic devices, clean energy, and sensors. In this review, after a general introduction to graphene and its derivatives, the synthesis, characterization, properties, and applications of graphene-based materials are discussed.

Graphene-Based Materials: Synthesis, Characterization, Properties, and Applications

Supercapacitors have drawn considerable attention in recent years due to their high specific power, long cycle life, and ability to bridge the power/energy gap between conventional capacitors and batteries/fuel cells. Nanostructured electrode materials have demonstrated superior electrochemical properties in producing high-performance supercapacitors. In this review article, we describe the recent progress and advances in designing nanostructured supercapacitor electrode materials based on various dimensions ranging from zero to three. We highlight the effect of nanostructures on the properties of supercapacitors including specific capacitance, rate capability and cycle stability, which may serve as a guideline for the next generation of supercapacitor electrode design.

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Supercapacitor electrode materials: nanostructures from 0 to 3 dimensions

Three-dimensional (3D) N-doped graphene aerogel (N-GA)-supported Fe3O4 nanoparticles (Fe3O4/N-GAs) as efficient cathode catalysts for the oxygen reduction reaction (ORR) are reported. The graphene hybrids exhibit an interconnected macroporous framework of graphene sheets with uniform dispersion of Fe3O4 nanoparticles (NPs). In studying the effects of the carbon support on the Fe3O4 NPs for the ORR, we found that Fe3O4/N-GAs show a more positive onset potential, higher cathodic density, lower H2O2 yield, and higher electron transfer number for the ORR in alkaline media than Fe3O4 NPs supported on N-doped carbon black or N-doped graphene sheets, highlighting the importance of the 3D macropores and high specific surface area of the GA support for improving the ORR performance. Furthermore, Fe3O4/N-GAs show better durability than the commercial Pt/C catalyst.

3D Nitrogen-Doped Graphene Aerogel-Supported Fe3O4 Nanoparticles as Efficient Electrocatalysts for the Oxygen Reduction Reaction

Fluidized bed biomass gasifiers can be employed to produce hydrogen-rich gas. A non-premixed combustion model is used for biomass air-steam gasification in the gasifier, and the simulations were carried out by using the FLUENT 6.0 software. The simulation results are compared with the experimental data. The effects of the steam to biomass ratio (S/B), the equivalence ratio (ER), and the size of biomass particles on the hydrogen yield were studied. Meanwhile, the distributions of hydrogen inside the gasifier at different conditions are also described.

Non-premixed Combustion Model of Fluidized Bed Biomass Gasifier for Hydrogen-Rich Gas

Precise detection of the tumor environment for cancer diagnosis has been strongly demanded for further therapies. Here, a redox-responsive fluorescence switch off/on system PCQ was designed and synthesized conjugated with near-infrared (NIR) cyanine dyes (Cy5.5) and relevant quencher (FQ) in mixed polymeric micelles (PCy and PFQ). The mixed PCQ micelles were prepared with two kinds of polymers with poly(oligo (ethylene glycol) methacrylate) (POEGMA) as the hydrophilic shell, in which fluorescence emission was quenched by fluorescence resonance energy transfer (FRET) effect. The FQ was conjugated with POEGMA by disulfide linkage, which could be broken with a redox environment such as high glutathione (GSH) concentration in tumor cells. After the PCQ micelles got into tumor cells, PFQ blocks in PCQ would be disassembled to recompose PCy micelles. During that process, drugs like doxorubicin (DOX) could be loaded inside and formed PCQ@DOX nanoparticles and then released for accurate NIR bioimaging and drug de...

Glutathione Triggered Near Infrared Fluorescence Imaging-Guided Chemotherapy by Cyanine Conjugated Polypeptide.

Sharp pH-sensitive amphiphilic polypeptide macrophotosensitizer for near infrared imaging-guided photodynamic therapy.

Films were formed by casting and shearing ethyl cellulose in chloroform at high coating speed and thin coating thickness. The films were used as alignment layers for liquid crystals. Atomic force microscopy and polarizing optical microscopy (POM) were used to identify the banded-texture structure of the films. The alignments of nematic liquid crystal 4-cyano-4′-n-pentylbiphenyl (5CB) droplets on the films were observed by POM. Furthermore, the time-dependent alignment behaviour of 5CB on the films was recorded and studied.



© 2003 Society of Chemical Industry

Alignment behaviour of liquid crystals on ethyl cellulose films with banded-texture structure

Distinguished from commonly used Fe $_2$ O $_3$ and Fe $_3$ O $_4$ , a three-dimensional multilevel macro-micro-mesoporous structure of FeC $_2$ O $_4$ /graphene composite has been prepared as binder-free electrode for supercapacitors. The as-prepared materials are composed of macroporous graphene and microporous/mesoporous ferrous oxalate. Generally, the decomposition voltage of water is 1.23 V and the practical voltage window limit is about 2 V for asymmetric supercapacitors in aqueous electrolytes. When FeC $_2$ O $_4$ /rGO hydrogel was used as the negative electrode and a pure rGO hydrogel was used as the positive electrode, the asymmetrical supercapacitor voltage window raised to 1.7 V in KOH (1.0 mol/L) electrolyte and reached up to 2.5 V in a neutral aqueous Na $_2$ SO $_4$ (1.0 mol/L) electrolyte. Correspondingly it also exhibits a high performance with an energy density of 59.7 Wh/kg. By means of combining a metal oxide that owns micro-mesoporous structure with graphene, this work provides a new opportunity for preparing high-voltage aqueous asymmetric supercapacitors without addition of conductive agent and binder.

Lifeng Yan

Papers

Non-premixed Combustion Model of Fluidized Bed Biomass Gasifier for Hydrogen-Rich Gas

Glutathione Triggered Near Infrared Fluorescence Imaging-Guided Chemotherapy by Cyanine Conjugated Polypeptide.

Sharp pH-sensitive amphiphilic polypeptide macrophotosensitizer for near infrared imaging-guided photodynamic therapy.

Alignment behaviour of liquid crystals on ethyl cellulose films with banded-texture structure

3D macro-micro-mesoporous FeC2O4/graphene hydrogel electrode for high-performance 2.5 V aqueous asymmetric supercapacitors