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The in situ growth of Sn/SnO heterostructured nanospheres embedded in crumpled graphene is based on a new strategy for the calcination of tin oleate coating on the crystal surface of sodium carbonate. Sn/SnO nanospheres and crumpled graphene are acquired simultaneously without external forces involved. The obtained composite exhibits superior electrochemical properties when used as an anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Silicene, the ultimate scaling of a silicon atomic sheet in a buckled honeycomb lattice, represents a monoelemental class of two-dimensional (2D) materials similar to graphene but with unique potential for a host of exotic electronic properties. Nonetheless, there is a lack of experimental studies largely due to the interplay between material degradation and process portability issues. This review highlights the state-of-the-art experimental progress and future opportunities in the synthesis, characterization, stabilization, processing and experimental device examples of monolayer silicene and its derivatives. The electrostatic characteristics of the Ag-removal silicene field-effect transistor exhibit ambipolar charge transport, corroborating with theoretical predictions on Dirac fermions and Dirac cone in the band structure. The electronic structure of silicene is expected to be sensitive to substrate interaction, surface chemistry, and spin–orbit coupling, holding great promise for a variety of novel applications, such as topological bits, quantum sensing, and energy devices. Moreover, the unique allotropic affinity of silicene with single-crystalline bulk silicon suggests a more direct path for the integration with or revolution to ubiquitous semiconductor technology. Both the materials and process aspects of silicene research also provide transferable knowledge to other Xenes like stanene, germanene, phosphorene, and so forth. [ABSTRACT FROM AUTHOR]

Two-dimensional semiconductors (2DSCs) have attracted considerable attention as atomically thin channel materials for field-effect transistors. Each layer in 2DSCs consists of a single- or few-atom-thick, covalently bonded lattice, in which all carriers are confined in their atomically thin channel with superior gate controllability and greatly suppressed OFF-state current, in contrast to typical bulk semiconductors plagued by short channel effects and heat generation from static power. Additionally, 2DSCs are free of surface dangling bonds that plague traditional semiconductors, and hence exhibit excellent electronic properties at the limit of single atom thickness. Therefore, 2DSCs can offer significant potential for the ultimate transistor scaling to single atomic body thickness. Earlier studies of graphene transistors have been limited by the zero bandgap and low ON–OFF ratio of graphene, and transition metal dichalcogenide (TMDC) devices are typically plagued by insufficient carrier mobility. To this end, considerable efforts have been devoted towards searching for new 2DSCs with optimum electronic properties. Within a relatively short period of time, a large number of 2DSCs have been demonstrated to exhibit unprecedented characteristics or unique functionalities. Here we review the recent efforts and progress in exploring novel 2DSCs beyond graphene and TMDCs for ultra-thin body transistors, discussing the merits, limits and prospects of each material. [ABSTRACT FROM AUTHOR]

Graphene, despite being the best known strong and electrical/thermal conductive material, has found limited success in practical applications, mostly due to difficulties in the formation of desired large-scale highly organized structures. Our discovery of a liquid crystalline phase formation in graphene oxide dispersion has enabled a broad spectrum of highly aligned graphene-based structures, including films, fibers, membranes, and mesoscale structures. In this review, the current understanding of the structure–property relationship of graphene oxide liquid crystals (GOLCs) is overviewed. Various synthetic methods and parameters that can be optimized for GOLC phase formation are highlighted. Along with the results from different characterization methods for the identification of the GOLC phases, the typical characteristics of different types of GOLC phases introduced so far, including nematic, lamellar and chiral phases, are carefully discussed. Finally, various interesting applications of GOLCs are outlined together with the future prospects for their further developments. [ABSTRACT FROM AUTHOR]

The discovery of graphene opened a door for manufacturing and investigating two-dimensional (2D) materials. After more than ten years of development, 2D materials have become one of the most important topics in materials research, with dozens of new materials having been synthesized experimentally and even more predicted theoretically. In this review, we provide a comprehensive overview of the fabrication of 2D materials based on epitaxial growth in an ultra-high vacuum (UHV) experimental environment and the investigation of their physical and chemical properties. In particular, we focus on techniques like intercalation, templated molecular adsorption, and direct selenization and tellurization of metal substrates. We discuss progress in fabrication methods of monatomic and binary 2D materials and highlight their interesting and quite unusual physical properties. Finally, we assess future directions of research in this field, where breakthroughs can be expected, and indicate where investments in additional research might be most rewarding scientifically. [ABSTRACT FROM AUTHOR]

The sp3-hybridized group 14 graphane analogues are a unique family of 2D materials in which every atom requires a terminal ligand for stability. Consequently, the optical, electronic, and thermal properties of these materials can be manipulated via covalent chemistry. Herein, we review the methodologies for preparing these materials, and compare their functionalization densities to Si/Ge(111) surfaces and other covalently terminated 2D materials. We discuss how the electronic structure, optical properties, and thermal stability of the 2D framework can be broadly tuned with the ligand identity and framework element. We highlight their recent application in electronics, optoelectronics, photocatalysis, and batteries. Overall, these materials are an intriguing regime in materials design in which both surface functionalization and solid-state chemistry can be uniquely exploited to systematically design properties and phenomena. [ABSTRACT FROM AUTHOR]

Two-dimensional layered materials (2DLMs) have attracted a tremendous amount of attention as photodetectors due to their fascinating features, including high potentials in new-generation electronic devices, wide coverage of bandgaps, ability to construct van der Waals heterostructures, extraordinary light–mass interaction, strong mechanical flexibility, and the capability of enabling synthesis of 2D nonlayered materials. Until now, most attention has been focused on the well-known graphene and transition metal dichalcogenides (TMDs). However, a growing number of functional materials (more than 5619) with novel optoelectronic and electronic properties are being re-discovered, thereby widening the horizon of 2D libraries. In addition to showing common features of 2DLMs, these new 2D members may bring new opportunities to their well-known analogues, like wider bandgap coverage, direct bandgaps independence with thickness, higher mechanical flexibility, and new photoresponse phenomena. The impressive results communicated so far testify that they have shown high potentials with photodetections covering THz, IR, visible, and UV ranges with comparable or even higher performances than well-known TMDs. Here, we give a comprehensive review on the state-of-the-art photodetections of two-dimensional materials beyond graphene and TMDs. The review is organized as follows: fundamentals of photoresponse first are discussed, followed by detailed photodetections of new 2D members including both layered and non-layered ones. After that, photodiodes and hybrid structures based on these new 2D materials are summarized. Then, the integration of these 2D materials with flexible substrates is reviewed. Finally, we conclude with the current research status of this area and offer our perspectives on future developments. We hope that, through reading this manuscript, readers will quickly have a comprehensive view on this research area. [ABSTRACT FROM AUTHOR]

The fabrication of graphene electrode with three-dimensional (3D) porous architecture would be highly desirable for electrochemical (bio-)sensing. Direct-laser-writing (DLW) on polyimide sheet has been recognized as an advance approach to pattern 3D porous graphene frameworks (3DPGFs)-based electrode. Herein, taking advantages of this straightforward and cost-effective DLW technique, we demonstrated the scalable and robust fabrication of a new type of 3DPGFs-based electrode patterned on the surface of indium−tin oxide (ITO) glass, denoted as 3DPGF@ITO. In this study, polyimide layer was synthesized on ITO glass surface not only to act as a sacrificial precursor for the in situ growth of 3DPGFs, but also to serve as a passivation layer for the effective separation of 3DPGFs working area and ITO contact pad. Importantly, the laser-induced 3DPGFs on ITO surface exhibit a 3D hierarchical and macroporous architecture consisting of interconnected multi-layered graphene sheets with large surface area and abundant edge-plane-like defective sites. These appealing features render the proposed 3DPGF@ITO electrode with marked improvement in electrochemical performance over traditional commercial electrodes. Finally, the developed 3DPGF@ITO electrode was successfully applied as a working electrode to selectively detect three important biospecies, namely, ascorbic acid, dopamine, and uric acid, in their ternary mixture with a high resolution of oxidation potentials. Thus, we envision that the 3DPGF@ITO electrode will open highly promising perspectives for the development of sensitive electrode-based (bio-)sensors. [ABSTRACT FROM AUTHOR]

Graphene, a single two-dimensional sheet of carbon atoms with an arrangement mimicking the honeycomb hexagonal architecture, has captured immense interest of the scientific community since its isolation in 2004. Besides its extraordinarily high electrical conductivity and surface area, graphene shows a long spin lifetime and limited hyperfine interactions, which favors its potential exploitation in spintronic and biomedical applications, provided it can be made magnetic. However, pristine graphene is diamagnetic in nature due to solely sp2 hybridization. Thus, various attempts have been proposed to imprint magnetic features into graphene. The present review focuses on a systematic classification and physicochemical description of approaches leading to equip graphene with magnetic properties. These include introduction of point and line defects into graphene lattices, spatial confinement and edge engineering, doping of graphene lattice with foreign atoms, and sp3 functionalization. Each magnetism-imprinting strategy is discussed in detail including identification of roles of various internal and external parameters in the induced magnetic regimes, with assessment of their robustness. Moreover, emergence of magnetism in graphene analogues and related 2D materials such as transition metal dichalcogenides, metal halides, metal dinitrides, MXenes, hexagonal boron nitride, and other organic compounds is also reviewed. Since the magnetic features of graphene can be readily masked by the presence of magnetic residues from synthesis itself or sample handling, the issue of magnetic impurities and correct data interpretations is also addressed. Finally, current problems and challenges in magnetism of graphene and related 2D materials and future potential applications are also highlighted. [ABSTRACT FROM AUTHOR]

The advancement of molecular electronics and spintronics requires novel hybrid materials with synergistic magnetic and electrical properties. The non-covalent functionalization of highly conductive graphene with magnetically bistable spin crossover (SCO) complexes may yield such a multifunctional material. In this regard, a graphene-Fe(ii) SCO complex hybrid (Gr-SCO) has been prepared by non-covalently anchoring a pyrene decorated SCO complex with solution phase pre-exfoliated few-layer graphene sheets. SQUID magnetometry revealed the preservation of SCO in the Gr-SCO hybrid material exhibiting more gradual spin state switching characteristics than in the bulk molecular complex. This persistence of SCO of a molecular Fe(ii) complex upon anchoring on the graphene surface has consequences towards the realization of SCO based applications: in (i) reversible spin state dependent band gap tuning of graphene with an SCO complex analogous to chemical doping of graphene, and (ii) to probe the spin state dependence of electrical conductivity modulation by wiring the anchoring group (pyrene) tethered SCO complex between chemically robust few-layer graphene electrodes. [ABSTRACT FROM AUTHOR]

Beside activity, electrocatalyst stability is gaining in importance. The most common degradation mechanism is the loss of the active surface area due to nanoparticle growth via coalescence/agglomeration. We propose a particle confinement strategy via vertically oriented graphene deposition to overcome degradation of the nanoparticles. [ABSTRACT FROM AUTHOR]

The first report of oxygen functionalized few-layer graphene (OFG) having an interlayer distance of 3.6 Å as an excellent proton conductor (8.7 × 10−3 S cm−1 at 80 °C, 95% RH) utilizing hydrophilic oxygen functionalities present at sheet edges bypassing the theoretical limitation of proton conduction through a basal plane. The synthesized OFG also exhibited excellent supercapacitor performance (296 F g−1). [ABSTRACT FROM AUTHOR]

Microfluidic strategies to enable the growth and subsequent serial crystallographic analysis of micro-crystals have the potential to facilitate both structural characterization and dynamic structural studies of protein targets that have been resistant to single-crystal strategies. However, adapting microfluidic crystallization platforms for micro-crystallography requires a dramatic decrease in the overall device thickness. We report a robust strategy for the straightforward incorporation of single-layer graphene into ultra-thin microfluidic devices. This architecture allows for a total material thickness of only ∼1 μm, facilitating on-chip X-ray diffraction analysis while creating a sample environment that is stable against significant water loss over several weeks. We demonstrate excellent signal-to-noise in our X-ray diffraction measurements using a 1.5 μs polychromatic X-ray exposure, and validate our approach via on-chip structure determination using hen egg white lysozyme (HEWL) as a model system. Although this work is focused on the use of graphene for protein crystallography, we anticipate that this technology should find utility in a wide range of both X-ray and other lab on a chip applications. [ABSTRACT FROM AUTHOR]

A novel electrochemical method has been developed towards cholesterol detection based on competitive host–guest interaction by selecting methylene blue (MB) and calix[6]arene functionalized graphene (CX6–Gra) as the “reporter pair”. In the presence of cholesterol, the MB molecules are displaced by cholesterol in the CX6–Gra.MB complex, leading to a “switch off” electrochemical response. A linear response range of 0.50 to 50.00 μM for cholesterol with a low detection limit of 0.20 μM (S/N = 3) was obtained by using the proposed method. This method could be successfully utilized to detect cholesterol in serum samples, and may be expanded to the analysis of other non-electroactive species. Besides, the host–guest interaction between cholesterol and CX6 was studied by molecular modeling calculations, which revealed that the complexation could reduce the energy of the system and the complex of a 1 : 1 host–guest stoichiometry had the lowest binding free energy of −8.01 kcal mol−1. In addition, the constructed electrochemical sensing platform is important as it does not use any enzyme or antibody for the detection of cholesterol efficiently and selectively over common interfering species. [ABSTRACT FROM AUTHOR]

Graphene is a well-known two-dimensional material that exhibits preeminent electrical, mechanical and thermal properties owing to its unique one-atom-thick structure. Graphene and its derivatives (e.g., graphene oxide) have become emerging nano-building blocks for separation membranes featuring distinct laminar structures and tunable physicochemical properties. Extraordinary molecular separation properties for purifying water and gases have been demonstrated by graphene-based membranes, which have attracted a huge surge of interest during the past few years. This tutorial review aims to present the latest groundbreaking advances in both the theoretical and experimental chemical science and engineering of graphene-based membranes, including their design, fabrication and application. Special attention will be given to the progresses in processing graphene and its derivatives into separation membranes with three distinct forms: a porous graphene layer, assembled graphene laminates and graphene-based composites. Moreover, critical views on separation mechanisms within graphene-based membranes will be provided based on discussing the effect of inter-layer nanochannels, defects/pores and functional groups on molecular transport. Furthermore, the separation performance of graphene-based membranes applied in pressure filtration, pervaporation and gas separation will be summarized. This article is expected to provide a compact source of relevant and timely information and will be of great interest to all chemists, physicists, materials scientists, engineers and students entering or already working in the field of graphene-based membranes and functional films. [ABSTRACT FROM AUTHOR]

The demand for flexible/wearable electronic devices that have aesthetic appeal and multi-functionality has stimulated the rapid development of flexible supercapacitors with enhanced electrochemical performance and mechanical flexibility. After a brief introduction to flexible supercapacitors, we summarize current progress made with graphene-based electrodes. Two recently proposed prototypes for flexible supercapacitors, known as micro-supercapacitors and fiber-type supercapacitors, are then discussed. We also present our perspective on the development of graphene-based electrodes for flexible supercapacitors. [ABSTRACT FROM AUTHOR]

Graphene nanosheets arranged perpendicularly to the substrate surface, i.e., vertically-oriented graphenes (VGs), have many unique morphological and structural features that can lead to exciting properties. Plasma-enhanced chemical vapor deposition enables the growth of VGs on various substrates using gas, liquid, or solid precursors. Compared with conventional randomly-oriented graphenes, VGs' vertical orientation on the substrate, non-agglomerated morphology, controlled inter-sheet connectivity, as well as sharp and exposed edges make them very promising for a variety of applications. The focus of this tutorial review is on plasma-enabled simple yet efficient synthesis of VGs and their properties that lead to emerging energy and environmental applications, ranging from energy storage, energy conversion, sensing, to green corona discharges for pollution control. [ABSTRACT FROM AUTHOR]

The parent skeleton of BN heterocoronene with three BN units and C3 symmetry was synthesized as a model compound of BN-doped graphene. Further investigation of this graphene-type molecule revealed the important role of BN doping in opening the bandgap and modulating the electronic properties. [ABSTRACT FROM AUTHOR]

Graphite sulphate is used as a precursor to graphene for the first time. The positively charged graphene layers react with water to yield a processable graphene derivative. The unprecedented low density of defects is determined to be 0.06% on average and may open the way for electronic applications. [ABSTRACT FROM AUTHOR]

The transfer of chemical vapor deposition (CVD)-grown graphene is the prerequisite for many applications. Herein, we introduce a simple and eco-friendly electrochemical technique to transfer graphene using agarose gel as the solid electrolyte and a mechanical support layer for graphene sheets. This transfer technique will be a perfect candidate for the industrial applications of graphene. [ABSTRACT FROM AUTHOR]

A review of articles, including “Photochromism in sound-induced alignment of a diarylethene supramolecular nanofibre" by Yasuhisa Hotta and others, “High-yield production of highly conductive graphene via reversible covalent chemistry" by Zhe Ji and others, and “Bismuth oxyiodide nanosheets: a novel high-energy anode material for lithium-ion batteries" by Chaoji Chen and others, which appeared in the periodical “ChemComm" in 2015 is presented.

Microporous nickel phosphite [Ni11(HPO3)8(OH)6] nanocrystals were prepared using a hydrothermal method, and were successfully applied as a positive electrode in a flexible all solid-state asymmetric supercapacitor. Because of the specific micro/nanostructure, the flexible solid-state asymmetric supercapacitor can achieve a maximum energy density of 0.45 mW h cm-3, which is higher than most reported supercapacitors. More importantly, the device performance remains efficient for 10000 cycles. [ABSTRACT FROM AUTHOR]

We describe a series of functionalized N-containing heterosuperbenzenes, created with a view to investigating the strategic role of methoxy substituents in (i) promoting cyclodehydrogenation and (ii) tuning the electronic properties and (iii) the supramolecular order in the resultant fused products. [ABSTRACT FROM AUTHOR]

Hybrid lamellar porous electrodes with excellent electrochemical performance were successfully fabricated by homogeneously intercalating single-walled carbon nanotubes into the lamellar assembled WS2 nanosheets through vacuum filtration. [ABSTRACT FROM AUTHOR]

CuInTe2/graphene composites were fabricated by spark plasma sintering and their thermoelectric properties were investigated. Embedding graphene sheets into CuInTe2 led to decreased thermal conductivity, which can be ascribed to the enhanced phonon scattering by the interface between graphene and the matrix. An improved dimensionless figure of merit (ZT) of 0.40 at 700 K was achieved in a CuInTe2/graphene composite with a mass ratio of 80 : 1. [ABSTRACT FROM AUTHOR]

The Ni3S2/graphene nanocomposites were designed and successfully prepared by a facile hydrothermal method, using nickel(ii) alkyldithiocarbonatio complexes [Ni(S2COC6H11)2] and graphene oxide as the raw materials. Graphene sheets were covered with Ni3S2 nanoparticles having diameters in the range of 8–28 nm. Electrochemical properties showed that Ni3S2/graphene have a lower resistance and a better electrochemical activity. Moreover, the pseudo second-order kinetic model can well-describe the adsorption kinetics of methyl orange on Ni3S2/graphene. [ABSTRACT FROM AUTHOR]

In this paper, we present the synthesis of Ni nanoparticles supported on graphene (Ni/G) using graphene oxide (GO) and Ni2+ ions as starting materials. GO is mixed with NiCl2 solution and treated by hydrazine. Hydrazine both reduces the GO and forms a complex with nickel(ii). A treatment in the tubular furnace allows decomposing the nickel-hydrazine complex into Ni metallic nanoparticles as well as further reducing the GO into graphene. The materials are characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and thermogravimetry–mass spectrometry as well as tested for methanol electrooxidation in alkaline medium. [ABSTRACT FROM AUTHOR]

A general route for the functionalization of graphene and graphene derivatives with a low molecular weight polymer by thiol-radical reactions is reported. Polymer-modified graphene is employed as a filler for high density polyethylene to generate materials with good electrical conductivity. [ABSTRACT FROM AUTHOR]

Few-layered boron carbon nitride nanosheets are synthesized by a simple and environmentally friendly process. The BCN nanosheets have 2–6 atomic layers with high surface area and show enhanced storage performance in lithium batteries, as well as a stable capacity of ∼100 mA h g−1 at 2 A g−1 for 5000 cycles. [ABSTRACT FROM AUTHOR]

The article discusses graphene-related materials that show exciting electronic properties.