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

Recently a new, large family of two-dimensional (2D) early transition metal carbides and carbonitrides, called MXenes, was discovered. MXenes are produced by selective etching of the A element from the MAX phases, which are metallically conductive, layered solids connected by strong metallic, ionic, and covalent bonds, such as Ti2AlC, Ti3AlC2, and Ta4AlC3. MXenes ­combine the metallic conductivity of transition metal carbides with the hydrophilic nature of their hydroxyl or oxygen terminated surfaces. In essence, they behave as “conductive clays”. This article reviews progress—both ­experimental and theoretical—on their synthesis, structure, properties, intercalation, delamination, and potential applications. MXenes are expected to be good candidates for a host of applications. They have already shown promising performance in electrochemical energy storage systems. A detailed outlook for future research on MXenes is also presented.

25th Anniversary Article: MXenes: A New Family of Two‐Dimensional Materials

Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

Recent Advances in Ultrathin Two-Dimensional Nanomaterials

Graphene oxide: preparation, functionalization, and electrochemical applications.

Composite films of chemically converted graphene (CCG) and polyaniline nanofibers (PANI-NFs) were prepared by vacuum filtration the mixed dispersions of both components. The composite film has a layered structure, and PANI-NFs are sandwiched between CCG layers. Furthermore, it is mechanically stable and has a high flexibility; thus, it can be bent into large angles or be shaped into various desired structures. The conductivity of the composite film containing 44% CCG (5.5 × 102 S m−1) is about 10 times that of a PANI-NF film. Supercapacitor devices based on this conductive flexible composite film showed large electrochemical capacitance (210 F g−1) at a discharge rate of 0.3 A g−1. They also exhibited greatly improved electrochemical stability and rate performances.

Supercapacitors Based on Flexible Graphene/Polyaniline Nanofiber Composite Films

Recent progress in the study of graphene has triggered a gold rush for exploiting its possible applications in various areas. Graphene-containing carbonaceous materials have long been selected as electrodes in rechargeable lithium batteries. However, the understanding of the relationship between material structure and electrode performance is still poor due to the complexity of the carbon structures, which hinders the development of high performance batteries. Now it is time to focus on the structure–property relationship of carbonaceous electrodes again, but from the viewpoint of graphene.

Graphene-based electrode materials for rechargeable lithium batteries

Silicon has been touted as one of the most promising anode materials for next generation lithium ion batteries. Yet, how to build energetic silicon-based electrode architectures by addressing the structural and interfacial stability issues facing silicon anodes still remains a big challenge. Here, we develop a novel kind of self-supporting binder-free silicon-based anodes via the encapsulation of silicon nanowires (SiNWs) with dual adaptable apparels (overlapped graphene (G) sheaths and reduced graphene oxide (RGO) overcoats). In the resulted architecture (namely, SiNW@G@RGO), the overlapped graphene sheets, as adaptable but sealed sheaths, prevent the direct exposure of encapsulated silicon to the electrolyte and enable the structural and interfacial stabilization of silicon nanowires. Meanwhile, the flexible and conductive RGO overcoats accommodate the volume change of embedded SiNW@G nanocables and thus maintain the structural and electrical integrity of the SiNW@G@RGO. As a result, the SiNW@G@RGO elec...

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Adaptable Silicon–Carbon Nanocables Sandwiched between Reduced Graphene Oxide Sheets as Lithium Ion Battery Anodes

A novel strategy is developed for the large-scale fabrication of reduced graphene oxide films directly on flexible substrates in a controlled manner by the combination of a rod-coating technique and room-temperature reduction of graphene oxide. The as-prepared films display excellent uniformity, good transparency and conductivity, and great flexibility in a touch screen.

Rod‐Coating: Towards Large‐Area Fabrication of Uniform Reduced Graphene Oxide Films for Flexible Touch Screens

Novel graphene-confined tin nanosheets (G/Sn/G) are constructed using an elaborately designed glucose-assisted chemical protocol. The as-synthesized G/Sn/G are featured with significantly enhanced lithium storage properties when compared with other graphene-based 0D/2D composite nanostructures, disclosing the merits of the 2D/2D composite featured with a surface-to-surface integration formula between graphene and the second 2D phase.

Graphene-confined Sn nanosheets with enhanced lithium storage capability.

The unique properties of graphene render it as a versatile material applying in various energy-related devices. Solar cells with transparent and conductive graphene film as window electrode have exhibited considerable power conversion efficiency. The graphene-based materials used as anode in lithium ion secondary batteries displayed excellent cycling performance and high capacities. Supercapacitors with great potential for practical application have been fabricated as well using graphene-based materials as electrode. Graphene has emerged as a promising two-dimensional nanomaterial for developing economic and efficient energy-related devices. In this review, the recent progress concerning the application of graphene and graphene-based materials in clean energy-related devices has been summarized briefly. Copyright

Minghui Liang

Papers

Graphene-based electrode materials for rechargeable lithium batteries

Adaptable Silicon–Carbon Nanocables Sandwiched between Reduced Graphene Oxide Sheets as Lithium Ion Battery Anodes

Rod‐Coating: Towards Large‐Area Fabrication of Uniform Reduced Graphene Oxide Films for Flexible Touch Screens

Graphene-confined Sn nanosheets with enhanced lithium storage capability.

Application of graphene and graphene‐based materials in clean energy‐related devices