Search

The mechanochemical covalent functionalization of carbon-encapsulated iron nanoparticles (CEINs) is reported. Unprotected sugars (mannose, galactose, β-cyclodextrin) and amino sugars (glucosamine and chitosan) were successfully conjugated to the surface of CEINs. The developed grinding-induced methods employ (i) the 1,3-dipolar cycloadditions of nitrile oxides or azomethine ylides and (ii) amidation-type reactions with the inclusion of carboxyl-functionalized CEINs and amino sugars. All the developed mechanochemical processes are fast (reaction time 10 min) and result in high degrees of coverage (7.3–31.5 wt%). The presented functionalization routes also constitute easy to perform and environmentally improved protocols. Moreover, the use of toxic organic solvents is not required. A comprehensive study on the colloidal stability of the sugar-functionalized CEINs is also included in this work. The results of the turbidimetric analyses reveal that both grinding-induced formation of amide bonds and the cycloadditions of sugar moieties to the surface of CEINs result in the significant improvement of their colloidal stability. The highest stability of the aqueous dispersion was found for CEINs functionalized with β-cyclodextrin. The comparative studies between the classical wet approach and the grinding-induced functionalization of CEINs show that the herein developed environmentally improved method increases the colloidal stability three times. The crucial role of the mechanochemical approach in the covalent functionalization of CEINs and the improvement of their colloidal stability is discussed in this work. [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]

Among two dimensional (2D) van der Waals (vdW) layered materials such as graphene, which is used like a metal, and transition metal chalcogenides (TMdCs), which are used as semiconductors and metals, hexagonal boron nitride (hBN), which is used as an insulator, is ubiquitous as a building block to construct 2D vdW electronics for versatile tunneling devices. Monolayer and few-layer hBN films have been prepared with flake sizes of a few hundred micrometer via mechanical exfoliation and transfer methods. Another approach used to synthesize hBN films on a large scale is chemical vapor deposition (CVD). Although the single-crystal film growth of hBN on the wafer scale is the key to realizing realistic electronic applications, the various functionalities of hBN for 2D electronics are mostly limited to the microscale. Here, we review the recent progress for the large-area synthesis of hBN and other related vdW heterostructures via CVD, and the artificial construction of vdW heterostructures and 2D vdW electronics based on hBN, in terms of charge fluctuations, passivation, gate dielectrics, tunneling, Coulombic interactions, and contact resistances. The challenges and future perspectives for practical applications are also addressed. [ABSTRACT FROM AUTHOR]

Extensive research on two-dimensional (2D) materials has triggered the renaissance of an old topic, that is, the intercalation and exfoliation of layer materials. Such top-down exfoliation produced 2D materials and their dispersions have several advantages including low cost, scalable production capability, solution processability, and versatile functionalities stemming from the large number of species of layer materials, and show promising potential in many applications. In recent years, many new methods have been developed for exfoliating layer materials to 2D materials for different application purposes. In this review the different exfoliation approaches are first systematically analyzed from the viewpoint of methodology, and the advantages and disadvantages of each method are compared. Second, the assembly of exfoliated 2D materials into macrostructures by solution-based techniques is summarized. Third, the state-of-the-art applications of 2D material dispersions and their assemblies in electronics and optoelectronics, electrocatalysis, energy storage, etc., are discussed. Finally, insights and perspectives on current research challenges and future opportunities regarding the exfoliation and applications of 2D materials in dispersions are considered. [ABSTRACT FROM AUTHOR]

The past decade has witnessed tremendous research efforts devoted to two-dimensional (2D) materials and great progress made in both their fundamental studies and technique development. 2D light-emitting materials such as transition-metal dichalcogenides (TMDs) and phosphorene are receiving particular attention as a result of their intriguing electronic, optical and optoelectronic properties. The ability to tune their layer numbers, engineer their dielectric environment, form alloys, create van der Waals heterostructures, etc. provides further means to modulate their properties which have led to a number of interesting luminescence features and potential applications in lighting, imaging and sensing. As the map of 2D materials has expanded over the past few years, 2D organic and organic–inorganic hybrid materials, such as 2D polymers, metal–organic frameworks (MOFs), and organic–inorganic hybrid perovskites, have also emerged with merits of low cost, chemical versatility and solution processibility. Importantly, the wide tunability of their functional properties is enabled by the rational design and controlled modification of their compositions and structures at the molecular level. Herein, we present a critical review of 2D light-emitting materials by categorizing them into three main groups, namely 2D inorganic light-emitting materials, 2D organic light-emitting materials, and 2D organic–inorganic hybrid light-emitting materials. Within each group, we will describe their preparation methods and discuss their structural and chemical properties. Significant emphasis will be placed on strategies that can tune their luminescence properties, and their potential applications in various fields. Finally, we will summarize by stating the current challenges and future opportunities in the development of 2D light-emitting materials. [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]

As a two-dimensional (2D) material, molybdenum disulfide (MoS2) exhibits unique electronic and optical properties useful for a variety of optoelectronic applications including light harvesting. In this article, we review recent progress in the synthesis, properties and applications of MoS2 and related heterostructures. Heterostructured materials are developed to add more functionality or flexibility compared to single component materials. Our focus is on their novel properties and functionalities as well as emerging applications, especially in the areas of light energy harvesting or conversion. We highlight the correlation between structural properties and other properties including electronic, optical, and dynamic. Whenever appropriate, we also try to provide fundamental insight gained from experimental as well as theoretical studies. Finally, we discuss some current challenges and opportunities in technological applications of MoS2. [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 (2D) metal–organic framework (MOF) nanosheets are attracting increasing research attention due to their unique properties originating from their ultrathin thickness, large surface area and high surface-to-volume atom ratios. Many great advances have been made in the synthesis and application of 2D MOF nanosheets over the past few years. In this review, we summarize the recent advances in the synthesis of 2D MOF nanosheets by using top-down methods, e.g. sonication exfoliation, mechanical exfoliation, Li-intercalation exfoliation and chemical exfoliation, and bottom-up methods, i.e. interfacial synthesis, three-layer synthesis, surfactant-assisted synthesis, modulated synthesis, and sonication synthesis. In addition, the recent progress in 2D MOF nanosheet-based nanocomposites is also briefly introduced. The potential applications of 2D MOF nanosheets in gas separation, energy conversion and storage, catalysis, sensors and biomedicine are discussed. Finally, we give our personal insights into the challenges and opportunities for the future research of 2D MOF nanosheets and their composites. [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]

We report a novel and versatile fabrication strategy for functional nanonetwork-structured carbon nitride with Au nanoparticle yolks (FNNS-C3N4-Au) based on hairy poly(acrylic acid)-grafted SiO2 nanospheres (Au@SiO2-g-PAA). Benefiting from the three-dimensional nanonetwork structure and well-distributed Au nanoparticles, the as-prepared nanocomposites demonstrated excellent photocatalysis performances (degradation rate constant: 1.8 × 10−2 min−1). [ABSTRACT FROM AUTHOR]

Uniform FeS1.4(Dmim)0.5 (Dmim = 1-n-butyl-2,3-dimethylimidazolium cation) hybrid nanosheets were developed through an innovative combination–decomposition approach. More importantly, the obtained hybrid nanosheets demonstrate unprecedentedly high electrocatalytic activity, which represents the discovery of a novel, efficient Fe-based electrocatalyst and expands the scope of new types of electrolytic water oxidation. [ABSTRACT FROM AUTHOR]

We designed and synthesized three phosphorylated peptides as precursors of the same peptide Nap-YYY. We found that different precursors led to different materials with almost identical chemical compositions at the final stages. Only Nap-YpYY could form very uniform nanofibers in a stable supramolecular hydrogel by enzyme-instructed self-assembly (EISA) at the physiological temperature (37 °C). In contrast, de-phosphorylation of the other two precursors (Nap-pYYY and Nap-YYpY) resulted in diverse nanostructures in metastable hydrogels with precipitates. The formation of uniform nanomaterials in the stable hydrogels was due to the preorganization property of the precursor Nap-YpYY, which facilitated rapid folding and accelerated the kinetics of hydrogelation of the resulting peptide Nap-YYY generated by the EISA process. Our study demonstrated the importance of the precursor for the self-assembly of nanomaterials and provided a useful strategy to manipulate them. [ABSTRACT FROM AUTHOR]

We combine chiral amplification and host–guest chemistry to demonstrate an approach to achieve a switchable chiral assembly. After the addition of the guest coronene, homochiral honeycomb patterns transform into host–guest sunflower structures, in which supramolecular chirality is modulated dramatically. [ABSTRACT FROM AUTHOR]

Supercapacitors are attracting attention as energy storage devices but the energy density and cycle life of electrode materials require further improvement for commercial applications. To achieve this goal, a corn flake-like NiO nanostructure on nickel foam was synthesized using a facile electrodeposition method. X-ray diffraction, high resolution transmission electron microscopy, and field emission scanning electron microscopy confirmed the formation of a corn flake-like NiO nanostructure on nickel foam. The electrochemical properties of the as-prepared NiO nanostructure were analyzed by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The direct formation of a highly porous corn flake-like NiO nanostructure on nickel foam provided an excellent electronic charge transfer rate with a low equivalent series resistance and good ionic accessibility for strong supercapacitive behavior. The as-prepared NiO nanostructure on nickel foam exhibited a specific capacitance of 1717 F g−1 and a capacitance retention of 87% after 5000 cycles. The NiO//activated carbon asymmetric supercapacitor fabricated using a polyvinyl alcohol-KOH gel electrolyte showed high energy and power densities of 44 W h kg−1 and 14 kW kg−1, respectively. Overall, the corn flake-like NiO nanostructure on nickel foam is an excellent candidate for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Various types of nanomaterials such as magnetic nanoparticles, carbon nanostructures, metal oxides, noble metal nanoparticles, and ion imprinted polymers have been incorporated in new innovative approaches for speciation analysis. Small size, high surface to volume ratio, and high chemical reactivity are the properties which make them ideal sorbents for selective separation of chemical species. Nanostructures based on different modifications of the nanoparticles and combinations between them additionally increased the nano-strategies employed for on-line or off-line determination of particular chemical species of elements. The presented review is focused on the use of nanomaterials for speciation analysis, analytical procedures developed and their application for analysis of environmental, food and biological samples. Critical view points on the current limitations and their future perspective are presented. [ABSTRACT FROM AUTHOR]

InyZn1−yO nanostructures were processed through a solution-based strategy for optoelectronic-related functions. Their crystalline structure, phase purity and valence states of various transition metal ions existing within them were studied in detail using X-ray diffraction, Raman and X-ray photoelectron spectroscopic measurements. The morphological dimension of the nanostructures was observed to be of sheet-like form from the electron microscopic results, while the optical band gap was estimated to be around 3.13 eV using Tauc's plot. The luminescence measurements revealed the nanosheets to be associated with multiple defects through the wide sub-band edge emissions in the visible region. The origin of defect-related emission was also substantiated using Raman spectroscopy. The electrical properties of the nanosheets were studied from the Nyquist and Mott–Schottky plots, which were established through electrochemical impedance spectroscopic measurements. The optoelectronic capabilities of InyZn1−yO were investigated via establishing p–n architectures using silicon (p-Si) and studying their corresponding current–voltage (I–V) characteristics. UV photon irradiation was found to substantiate the potential of the fabricated heterostructures for optoelectronic functions. [ABSTRACT FROM AUTHOR]

We apply liquid nebulization (LN) in series with ion mobility spectrometry (IMS, using a differential mobility analyzer coupled to a condensation particle counter) to measure the size distribution functions (the number concentration per unit log diameter) of gold nanospheres in the 5–30 nm range, 70 nm × 11.7 nm gold nanorods, and albumin proteins originally in aqueous suspensions. In prior studies, IMS measurements have only been carried out for colloidal nanoparticles in this size range using electrosprays for aerosolization, as traditional nebulizers produce supermicrometer droplets which leave residue particles from non-volatile species. Residue particles mask the size distribution of the particles of interest. Uniquely, the LN employed in this study uses both online dilution (with dilution factors of up to 104) with ultra-high purity water and a ball-impactor to remove droplets larger than 500 nm in diameter. This combination enables hydrosol-to-aerosol conversion preserving the size and morphology of particles, and also enables higher non-volatile residue tolerance than electrospray based aerosolization. Through LN-IMS measurements we show that the size distribution functions of narrowly distributed but similarly sized particles can be distinguished from one another, which is not possible with Nanoparticle Tracking Analysis in the sub-30 nm size range. Through comparison to electron microscopy measurements, we find that the size distribution functions inferred via LN-IMS measurements correspond to the particle sizes coated by surfactants, i.e. as they persist in colloidal suspensions. Finally, we show that the gas phase particle concentrations inferred from IMS size distribution functions are functions of only of the liquid phase particle concentration, and are independent of particle size, shape, and chemical composition. Therefore LN-IMS enables characterization of the size, yield, and polydispersity of sub-30 nm particles. [ABSTRACT FROM AUTHOR]

A well-defined co-catalyst system TiO2 nanotube–Au (core)–Pt (shell) was demonstrated to be the combination of the localized surface plasmon effect of gold and excellent proton reduction nature of platinum. Furthermore, surface engineering by the descending Fermi energies of gold and platinum was beneficial to electron transfer. [ABSTRACT FROM AUTHOR]

One-dimensional nanostructured TiNb2O7 was prepared by a simple solution-based process and subsequent thermal annealing. The obtained anode materials exhibited excellent electrochemical performance with superior reversible capacity, rate capability and cyclic stability. [ABSTRACT FROM AUTHOR]

Nanomaterials have been widely used as multifunctional scaffolds and carriers in bone tissue engineering resulting from their versatile functionalities. Here, a classical Stöber method that combined the merits of an organic reagent-free hydrothermal route was introduced to rationally design and synthesize novel magnesium silicate hollow spheres (denoted as MgSiO3 hollow spheres). Due to the presence of mineral elements including silicon and magnesium, these well-prepared hollow structures exhibited positive effects in accelerated osteogenic differentiation. By using an osteoblastic cell line as example, namely MC3T3-E1, we investigated the in vitro toxicity of these hollow spheres via various classical methods including MTT assay, LDH assay, apoptosis, and morphology observation. Results indicated that these materials revealed extremely low systemic toxicity and high bio-compatibility. Moreover, cellular internalization observation demonstrated that these hollow spheres could be taken up by MC3T3-E1 cells in a time-dependent manner. This vigorous process of endocytosis could provide more raw materials for the following intracellular mineralization and bone regeneration. Results of ALP analysis and alizarin red staining indicated that these hollow spheres could clearly promote osteoblast differentiation and mineralization in a dose-dependent manner. Our study suggested that these magnesium silicate hollow spheres could act as promising candidates for enhanced bone regeneration and bone tissue engineering. [ABSTRACT FROM AUTHOR]

Nanomaterials with size- and structure-dependent properties have attracted much attention recently. However, it is still challenging to achieve large-scale fabrication of nanostructured arrays on flexible substrates at room temperature. Here, we report a facile procedure, inspired by eggshell formation, to synthesize high-order nanostructured flake arrays on a flexible Nafion membrane. We demonstrated, using Mn3(PO4)2·3H2O as a model, that a cation exchange Nafion membrane can function as a controller of cations and pH to provide the appropriate reaction environment for the nucleation and formation of rectangle-shaped Mn3(PO4)2·3H2O nanoflake arrays directly grown on the Nafion membrane substrate at room temperature. The bio-inspired approach offers a facile procedure for the large-scale synthesis of various nanostructures, in principle, at room temperature. The formation mechanism was investigated by tuning the experimental parameters. Interestingly, we also demonstrated that the hierarchical structures of the nanoflake arrays on flexible substrates showed impressive underwater superoleophobicity, similar to that of fish scales. [ABSTRACT FROM AUTHOR]

While the blood vessel is seldom the target tissue, almost all nanomedicine will interact with blood vessels and blood at some point of time along its life cycle in the human body regardless of their intended destination. Despite its importance, many bionanotechnologists do not feature endothelial cells (ECs), the blood vessel cells, or consider blood effects in their studies. Including blood vessel cells in the study can greatly increase our understanding of the behavior of any given nanomedicine at the tissue of interest or to understand side effects that may occur in vivo. In this review, we will first describe the diversity of EC types found in the human body and their unique behaviors and possibly how these important differences can implicate nanomedicine behavior. Subsequently, we will discuss about the protein corona derived from blood with foci on the physiochemical aspects of nanoparticles (NPs) that dictate the protein corona characteristics. We would also discuss about how NPs characteristics can affect uptake by the endothelium. Subsequently, mechanisms of how NPs could cross the endothelium to access the tissue of interest. Throughout the paper, we will share some novel nanomedicine related ideas and insights that were derived from the understanding of the NPs' interaction with the ECs. This review will inspire more exciting nanotechnologies that had accounted for the complexities of the real human body. [ABSTRACT FROM AUTHOR]

This paper reports the novel synthesis of uranyl sulphide (UO2S) thin films using the successive ionic layer adsorption and reaction (SILAR) technique at room temperature. Cationic exchange reaction was used to convert uranyl sulphide (UO2S) to silver sulphide (Ag2S). The influence of concentration variation on the structural and optical properties of UO2S and Ag2S thin films was investigated. The structural, surface morphological, elemental analysis and optical absorption studies were performed. Structural studies revealed that all the deposited films were nano-sized and amorphous in nature. Surface morphology showed that all the grains were spherical and granular in nature and grains got conglomerated to form a large particle. Also, the variations of the optical band gap and the width of the tail of localized states were represented as a function of various parameters. [ABSTRACT FROM AUTHOR]

Metal nanostructures display a multitude of technologically useful properties that can be tailored through fine-tuning of certain parameters, such as size, shape and composition. In many cases, the shape or morphology of metal nanostructures plays the most crucial role in the determination of their properties and their suitability in specific applications. In this tutorial review, we provide a summary of recent research that centers on metal nanostructures having anisotropically branched morphologies. The branched structural features that are exhibited by these materials endow them with unique properties that can be utilized in many important applications. The formation of branched architectures can be achieved in solution through a variety of synthetic strategies, four of which are highlighted in this review and these are: (1) seedless growth, (2) seeded growth, (3) templated growth, and (4) chemical etching. The usefulness of these anisotropically branched metal nanostructures in the areas of plasmonics, catalysis and biomedicine is also presented. [ABSTRACT FROM AUTHOR]

Graphene has emerged as a rapidly rising star in the field of materials science since its successful preparation in 2004. Due to its distinguished electrical, chemical and optical performances, graphene and its derivatives have also generated huge interest in analytical chemistry. This article critically and comprehensively reviews the emerging graphene-based electrochemical analysis, photochemical analysis and extraction. We present a review of the current literature concerning the electrochemical applications and advancements of graphene in the detection of metal ions, gases, nucleic acids, proteins, cells, bacteria and other molecules. Meanwhile, we summarize the application of graphene in photoanalysis (including graphene-based fluorescence resonance energy transfer sensors and optical sensors). In addition, we comment on the application and advantages of graphene in extraction. We emphasize the unique roles and advantages of graphene materials used in analytical chemistry. [ABSTRACT FROM AUTHOR]

Individual CoFe alloy nanoparticles and CoFe-MgO nanocomposites were prepared through thermal reduction of single-source layered double hydroxide (LDH) precursors at various temperatures. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) analyses to investigate the influence of reduction temperature on the composition, particle size and size distribution, as well as the magnetic properties of the resulting materials. XRD and SEM results show that the as-prepared CoFe alloy nanoparticles and CoFe-MgO nanocomposites display high crystallinity and high purity. The average particle size of individual CoFe nanoparticles increases with the increase of reduction temperature. In the presence of the MgO matrix, uniform CoFe alloy nanoparticles with a narrow diameter distribution (8-11 nm) were obtained. Magnetic measurements indicate that the saturation magnetization strength (Ms) of the resulting materials increases with reduction temperature. The individual CoFe alloy nanoparticles exhibit excellent soft magnetic behavior with an extremely high Ms value (213 emu g-1 at 800 °C), comparable to that of bulk CoFe alloy (230 emu g-1). For CoFe-MgO nanocomposites, small Ms values were obtained due to the small CoFe alloy particle size and low percentage of magnetic component. However, the coercivities are greatly enhanced (663 Oe at 450 °C) for the composites, implying their potential applications in data storage and other magnetic devices. [ABSTRACT FROM AUTHOR]

Photothermal therapy (PTT) is limited by unsuitable photothermal agents and near-infrared (NIR) light. Herein, self-assembled PEGylated WO3–x hierarchical nanostructures, which could serve as excellent laser-cavity mirrors, were successfully prepared via a simple one-pot solvothermal route. The as-prepared WO3–x hierarchical nanostructures displayed strong near-infrared absorption. The absorption of pure water at 980 nm is 30 times higher than that at 915 nm, and the temperature of water only increased by 3.4 °C under the irradiation of a 915 nm laser with a power density of 1.0 W cm−2 for 10 min, while the temperature of water increased as much as 15.1 °C for the 980 nm laser. With continuous excitation by 915 nm light, the photothermal conversion efficiency of these WO3–x hierarchical nanostructures was evaluated to be 28.1%. Thus, the WO3–x hierarchical nanostructures could serve as excellent laser-cavity mirrors of a 915 nm laser. The PTT study on cancer cells in vivo demonstrated that the WO3–x hierarchical nanostructures can generate enough heat for efficient photothermal therapy of cancer cells under the irradiation of a 915 nm laser with a power density of 1.2 W cm−2 over a short period (5–10 min). [ABSTRACT FROM AUTHOR]

The article discusses research related to the use of microfluidic devices in chemistry and biologica laboratories. A study which performs cytotoxicity testing of graphene oxide (GO) sheets, multi-wall carbon nanotubes (MWCNTs), and CdSe nanoparticles found negligible cytotoxicity for GO. Another study which examines the microscale structures on rice leaves revealed that liquids with a lower surface tension than water could not preserve their shape on the surface of a rice leaf.

A fast preparation of prickly copper quinoline sulfate spherical superstructures is reported. The superstructures were obtained based on a simple coordinative reaction between CuSO4 and quinoline (q) in a water–methanol system without assistance of any surfactant or template. The obtained spherical superstructures were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), UV-vis absorption and photoluminescence (PL) spectra. SEM observations showed that the as-obtained spherical superstructures were constructed from abundant nanoplates. Experiments discovered that the phase, size and morphology of the superstructures could be affected by some reactive parameters including the molar ratio of Cu2+/q and the volume ratio of water/methanol. A time-dependent shape evolution experiment confirmed that the growth of CuqSO4 spherical superstructures underwent a process from flowerlike structures, to spherical structures with pores, and finally to prickly spherical superstructures. [ABSTRACT FROM AUTHOR]

We report a facile method for the synthesis of Au@Pd nanostructures with controlled sizes and morphologies from flower-like to cuboctahedral shape by seed-mediated growth using Au nanospheres as seeds and cetylpyridinium chloride (CPC) as a surfactant. The use of CPC as a surfactant and its molar ratio with respect to Na2PdCl4 were critical factors to generate the Au@Pd nanostructures with flower-like morphology. In addition, the morphology of Au@Pd nanostructures could be easily controlled by changing the concentration of CPC in the reaction solution, where controlled reduction kinetics according to the concentration of CPC brought variety to the morphology of the Pd shell and eventually the Au@Pd nanostructures. The size of Au@Pd nanostructures could be also readily tuned in a controllable fashion by varying the concentration of Na2PdCl4. We also investigated the morphology-dependent electrocatalytic activities of Au@Pd nanostructures toward ethanol electrooxidation as a probe reaction. Thanks to their larger electroactive surface area and higher density of electroactive sites, the flower-like Au@Pd nanostructures exhibited 2.2 times enhanced electrocatalytic activity per Pd unit mass than cuboctahedral Au@Pd nanostructures. [ABSTRACT FROM AUTHOR]

The vapor–solid mechanism of 1D SiC nanostructure growth is examined. The chemical vapor deposition parameters were controlled to estimate their effects on SiC nanowhisker (NW) growth and cross-sectional microimages of the NWs were examined to identify the key factors which induce the initial NW growth. According to our careful investigation, we propose that noncatalytic NW growth is a kinetic driven process that occurs when a high density of small critically sized islands exist, which corresponds to the case of a low deposition rate and high surface diffusion. [ABSTRACT FROM AUTHOR]

Rare-earth (RE) doped transparent glass-ceramics are presented as very promising materials for optical applications. In this work, Transmission Electron Microscopy techniques have been used to structurally characterize a glass of composition 55SiO2–20Al2O3–15Na2O–10LaF3 (mol%), doped with 1 mol% Tm2O3, and the corresponding glass-ceramic. The proposed crystallization mechanism for this glass has been modified from the results obtained through advanced STEM/EDXS techniques. The parent glass contains phase separated regions mainly enriched in F and La and also in Al, Si and Tm. After annealing, 10–20 nm LaF3 nano-crystals are formed from these phase separated droplets. The partial incorporation of the doping Tm3+ ions into the LaF3 nano-crystals has been verified and the interphase crystal/glassy matrix has been more precisely characterized through EDXS. An Al enriched layer is formed around the crystals followed by a Si enriched shell, which greatly increase the viscosity in the periphery of the crystals, inhibiting further crystal growth and thus, keeping the nano size of the crystals. [ABSTRACT FROM AUTHOR]

The unique optical properties, such as size-tunable absorption and emission, caused semiconductor nanocrystals to attract a great deal of interest for recent technological developments. For the evaluation of semiconductor nanocrystals as new materials for various applications like optoelectronic devices, knowledge of the structure–property relationships is indispensable, but still presents a challenge. Here, we address these challenges for thioglycolic acid-capped CdTe nanocrystals with a focus on the quantification of thiol ligands, identification of the ligand shell structure and their influence on the optical properties of these nanocrystals. We present the use of a simple analytical technique, the Ellman's test, and ICP-OES analysis for the study of the surface chemistry of these nanomaterials. Together with theoretical calculations, the results of these studies show the strong influence of the amount of Cd–thiolates present in the ligand shell on the concentration-dependent emission properties, thereby providing the basis for a better understanding of the chemical nature of the NC–ligand interface. In this context, the present work contributes to the establishment of a clearer picture and better control of the surface chemistry, which will provide the basis for the design of highly emitting nanocrystals and the prediction of their applicability. [ABSTRACT FROM AUTHOR]

The article discusses the highlights of the 2012 Winter Conference on Plasma Spectrochemistry held in Tucson, Arizona on January 9-14. 12 symposia, three topical workshops, four poster sessions and 50 preconference short courses are cited as features of the event. Topics discussed include flow injection analysis, nanomaterial analysis, and laser-assisted plasma spectrochemistry. A lecture by Michael Ramsey on the use of microfabricated fluidic devices is also mentioned.