There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.

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Graphene and Graphene Oxide: Synthesis, Properties, and Applications

Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp 2 -bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

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Carbon-based Supercapacitors Produced by Activation of Graphene

Although electrochemical capacitors (ECs), also known as supercapacitors or ultracapacitors, charge and discharge faster than batteries, they are still limited by low energy densities and slow rate capabilities. We used a standard LightScribe DVD optical drive to do the direct laser reduction of graphite oxide films to graphene. The produced films are mechanically robust, show high electrical conductivity (1738 siemens per meter) and specific surface area (1520 square meters per gram), and can thus be used directly as EC electrodes without the need for binders or current collectors, as is the case for conventional ECs. Devices made with these electrodes exhibit ultrahigh energy density values in different electrolytes while maintaining the high power density and excellent cycle stability of ECs. Moreover, these ECs maintain excellent electrochemical attributes under high mechanical stress and thus hold promise for high-power, flexible electronics.

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Laser Scribing of High-Performance and Flexible Graphene-Based Electrochemical Capacitors

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

Optimizing the Crystallite Structure of Lignin‐Based Nanospheres by Resinification for High‐Performance Sodium‐Ion Battery Anodes

Pr2NiO4-Ag composite as cathode for low temperature solid oxide fuel cells: Effects of silver loading methods and amounts

Novel hierarchical porous carbon aerogels (PCAs) derived from amphiphilic carbonaceous material (ACM) have been mass-prepared via a facile solvent exchange induced self-assembly process and subsequent carbonization and KOH activation. The resulting products are stacked up by highly interconnected carbon nanoparticles with a certain amount of micropores and mesopores, which aggregate to build a three-dimensional macroporous architecture. The hierarchical porous structure facilitates fast ion transportation inside the electrode simultaneously preserving efficient ion surface electrochemical reactions. Capacitive and rate performances were evaluated by fabricating symmetric capacitors with both aqueous and organic electrolytes. The PCA-0.5 and PCA-1.0 electrodes exhibit superior specific capacitances of 261.2 and 227.9 F g−1 at a current density of 0.05 A g−1 in 6 M KOH electrolyte, and still remain 145.5 and 175.4 F g−1 as the current density increases to 100 A g−1, respectively. Remarkably, the PCA-0.5 and PCA-1.0 electrodes show stable cycle durability with a slight capacitance loss of 8.2 and 11.2 % after 5000 cycles at 1 A g−1, respectively. Furthermore, in organic electrolyte system, the PCA-1.0 electrode manifests an outstanding capacitance of 155.4 F g−1 at a current density of 0.05 A g−1. The encouraging results demonstrate that PCAs are a sort of promising and competitive supercapacitors electrode materials.

Mingming Chen

Papers

Optimizing the Crystallite Structure of Lignin‐Based Nanospheres by Resinification for High‐Performance Sodium‐Ion Battery Anodes

Pr2NiO4-Ag composite as cathode for low temperature solid oxide fuel cells: Effects of silver loading methods and amounts

Amphiphilic carbonaceous material-based hierarchical porous carbon aerogels for supercapacitors

A novel non-organic hydrothermal/hydrolysis method for preparation of well-dispersed Li4Ti5O12

Retarding Li dendrites growth via introducing porous g-C3N4 into polymer electrolytes for solid-state lithium metal batteries