Showing papers in "Advanced Materials in 2011"
TL;DR: 2D nanosheets, composed of a few Ti 3 C 2 layers and conical scrolls, produced by the room temperature exfoliation of Ti 3 AlC 2 in hydrofl uoric acid are reported, which opens a door to the synthesis of a large number of other 2D crystals.
Abstract: Currently, however, there are relatively few such atomically layered solids. [ 2–5 ] Here, we report on 2D nanosheets, composed of a few Ti 3 C 2 layers and conical scrolls, produced by the room temperature exfoliation of Ti 3 AlC 2 in hydrofl uoric acid. The large elastic moduli predicted by ab initio simulation, and the possibility of varying their surface chemistries (herein they are terminated by hydroxyl and/or fl uorine groups) render these nanosheets attractive as polymer composite fi llers. Theory also predicts that their bandgap can be tuned by varying their surface terminations. The good conductivity and ductility of the treated powders suggest uses in Li-ion batteries, pseudocapacitors, and other electronic applications. Since Ti 3 AlC 2 is a member of a 60 + group of layered ternary carbides and nitrides known as the MAX phases, this discovery opens a door to the synthesis of a large number of other 2D crystals. Arguably the most studied freestanding 2D material is graphene, which was produced by mechanical exfoliation into single-layers in 2004. [ 1 ] Some other layered materials, such as hexagonal BN, [ 2 ] transition metal oxides, and hydroxides, [ 4 ] as well as clays, [ 3 ] have also been exfoliated into 2D sheets. Interestingly, exfoliated MoS 2 single layers were reported as early as in 1986. [ 5 ] Graphene is fi nding its way to applications ranging from supercapacitor electrodes [ 6 ] to reinforcement in composites. [ 7 ] Although graphene has attracted more attention than all other 2D materials combined, its simple chemistry and the weak van der Waals bonding between layers in multilayer structures limit its use. Complex, layered structures that contain more than one element may offer new properties because they
6,846 citations
TL;DR: In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-Capacitance have been explored and show not only enhanced capacitance, but as well good cyclability.
Abstract: Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed.
2,497 citations
TL;DR: Considering future bottlenecks in raw materials, options for the recycling of rare-earth intermetallics for hard magnets will be discussed and their potential impact on energy efficiency is discussed.
Abstract: A new energy paradigm, consisting of greater reliance on renewable energy sources and increased concern for energy effi ciency in the total energy lifecycle, has accelerated research into energy-related technologies. Due to their ubiquity, magnetic materials play an important role in improving the effi ciency and performance of devices in electric power generation, conditioning, conversion, transportation, and other energy-use sectors of the economy. This review focuses on the state-of-the-art hard and soft magnets and magnetocaloric materials, with an emphasis on their optimization for energy applications. Specifi cally, the impact of hard magnets on electric motor and transportation technologies, of soft magnetic materials on electricity generation and conversion technologies, and of magnetocaloric materials for refrigeration technologies, are discussed. The synthesis, characterization, and property evaluation of the materials, with an emphasis on structure‐property relationships, are discussed in the context of their respective markets, as well as their potential impact on energy effi ciency. Finally, considering future bottlenecks in raw materials, options for the recycling of rare-earth intermetallics for hard magnets will be discussed.
2,465 citations
TL;DR: The major strategies for designing surfaces that prevent fouling due to proteins, bacteria, and marine organisms are reviewed and ongoing research in this area should result in the development of even better antifouling materials in the future.
Abstract: The major strategies for designing surfaces that prevent fouling due to proteins, bacteria, and marine organisms are reviewed. Biofouling is of great concern in numerous applications ranging from biosensors to biomedical implants and devices, and from food packaging to industrial and marine equipment. The two major approaches to combat surface fouling are based on either preventing biofoulants from attaching or degrading them. One of the key strategies for imparting adhesion resistance involves the functionalization of surfaces with poly(ethylene glycol) (PEG) or oligo(ethylene glycol). Several alternatives to PEG-based coatings have also been designed over the past decade. While protein-resistant coatings may also resist bacterial attachment and subsequent biofilm formation, in order to overcome the fouling-mediated risk of bacterial infection it is highly desirable to design coatings that are bactericidal. Traditional techniques involve the design of coatings that release biocidal agents, including antibiotics, quaternary ammonium salts (QAS), and silver, into the surrounding aqueous environment. However, the emergence of antibiotic- and silver-resistant pathogenic strains has necessitated the development of alternative strategies. Therefore, other techniques based on the use of polycations, enzymes, nanomaterials, and photoactive agents are being investigated. With regard to marine antifouling coatings, restrictions on the use of biocide-releasing coatings have made the generation of nontoxic antifouling surfaces more important. While considerable progress has been made in the design of antifouling coatings, ongoing research in this area should result in the development of even better antifouling materials in the future.
2,278 citations
TL;DR: Simultaneous enhancement of open-circuit voltage, short-circuits current density, and fill factor in highly efficient polymer solar cells by incorporating an alcohol/water-soluble conjugated polymer as cathode interlayer is domonstrated.
Abstract: Simultaneous enhancement of open-circuit voltage, short-circuit current density, and fill factor in highly efficient polymer solar cells by incorporating an alcohol/water-soluble conjugated polymer as cathode interlayer is domonstrated. When combined with a low-bandgap polymer PTB7 as the electron donor material, the power efficiency of the devices is improved to a certified 8.370%. Due to the drastic improvement in efficiency and easy utilization, this method opens new opportunities for PSCs from various material systems to improve towards 10% efficiency.
2,019 citations
TL;DR: This review will explore the materials properties of transparent conductors, covering traditional metal oxides and conductive polymers initially, but with a focus on current developments in nano-material coatings.
Abstract: Transparent electrodes are a necessary component in many modern devices such as touch screens, LCDs, OLEDs, and solar cells, all of which are growing in demand. Traditionally, this role has been well served by doped metal oxides, the most common of which is indium tin oxide, or ITO. Recently, advances in nano-materials research have opened the door for other transparent conductive materials, each with unique properties. These include CNTs, graphene, metal nanowires, and printable metal grids. This review will explore the materials properties of transparent conductors, covering traditional metal oxides and conductive polymers initially, but with a focus on current developments in nano-material coatings. Electronic, optical, and mechanical properties of each material will be discussed, as well as suitability for various applications.
1,947 citations
TL;DR: This article presents an overview of the essential aspects in the fabrication of silicon and some silicon/germanium nanostructures by metal-assisted chemical etching, and introduces templates based on nanosphere lithography, anodic aluminum oxide masks, interference lithographic, and block-copolymer masks.
Abstract: This article presents an overview of the essential aspects in the fabrication of silicon and some silicon/germanium nanostructures by metal-assisted chemical etching. First, the basic process and mechanism of metal-assisted chemical etching is introduced. Then, the various influences of the noble metal, the etchant, temperature, illumination, and intrinsic properties of the silicon substrate (e.g., orientation, doping type, doping level) are presented. The anisotropic and the isotropic etching behaviors of silicon under various conditions are presented. Template-based metal-assisted chemical etching methods are introduced, including templates based on nanosphere lithography, anodic aluminum oxide masks, interference lithography, and block-copolymer masks. The metal-assisted chemical etching of other semiconductors is also introduced. A brief introduction to the application of Si nanostructures obtained by metal-assisted chemical etching is given, demonstrating the promising potential applications of metal-assisted chemical etching. Finally, some open questions in the understanding of metal-assisted chemical etching are compiled.
1,689 citations
TL;DR: Narrow bandgap conjugated polymers in combination with fullerene acceptors, as well as the values used for the absolute potentials of standard electrodes, can complicate the comparison of materials properties and determination of structure/property relationships.
Abstract: Narrow bandgap conjugated polymers in combination with fullerene acceptors are under intense investigation in the field of organic photovoltaics (OPVs). The open circuit voltage, and thereby the power conversion efficiency, of the devices is related to the offset of the frontier orbital energy levels of the donor and acceptor components, which are widely determined by cyclic voltammetry. Inconsistencies have appeared in the use of the ferrocenium/ferrocene (Fc + /Fc) redox couple, as well as the values used for the absolute potentials of standard electrodes, which can complicate the comparison of materials properties and determination of structure/property relationships.
1,681 citations
TL;DR: This Review tries to summarize what remarkable progress in multiferroic magnetoelectric composite systems has been achieved in most recent few years, with emphasis on thin films; and to describe unsolved issues and new device applications which can be controlled both electrically and magnetically.
Abstract: Multiferroic magnetoelectric composite systems such as ferromagnetic-ferroelectric heterostructures have recently attracted an ever-increasing interest and provoked a great number of research activities, driven by profound physics from coupling between ferroelectric and magnetic orders, as well as potential applications in novel multifunctional devices, such as sensors, transducers, memories, and spintronics. In this Review, we try to summarize what remarkable progress in multiferroic magnetoelectric composite systems has been achieved in most recent few years, with emphasis on thin films; and to describe unsolved issues and new device applications which can be controlled both electrically and magnetically.
1,642 citations
TL;DR: This progress report covers both basic concepts and recent advances in the development of HA‐based hydrogels for biomedical applications.
Abstract: Hyaluronic acid (HA), an immunoneutral polysaccharide that is ubiquitous in the human body, is crucial for many cellular and tissue functions and has been in clinical use for over thirty years. When chemically modified, HA can be transformed into many physical forms-viscoelastic solutions, soft or stiff hydrogels, electrospun fibers, non-woven meshes, macroporous and fibrillar sponges, flexible sheets, and nanoparticulate fluids-for use in a range of preclinical and clinical settings. Many of these forms are derived from the chemical crosslinking of pendant reactive groups by addition/condensation chemistry or by radical polymerization. Clinical products for cell therapy and regenerative medicine require crosslinking chemistry that is compatible with the encapsulation of cells and injection into tissues. Moreover, an injectable clinical biomaterial must meet marketing, regulatory, and financial constraints to provide affordable products that can be approved, deployed to the clinic, and used by physicians. Many HA-derived hydrogels meet these criteria, and can deliver cells and therapeutic agents for tissue repair and regeneration. This progress report covers both basic concepts and recent advances in the development of HA-based hydrogels for biomedical applications.
1,575 citations
TL;DR: In this review, recent developments in the area of high-electron-mobility diimides based on rylenes and related aromatic cores, particularly perylene- and naphthalene-diimide-based small molecules and polymers, for application in high-performance organic field-effect transistors and photovoltaic cells are summarized and analyzed.
Abstract: Organic electron-transporting materials are essential for the fabrication of organic p-n junctions, photovoltaic cells, n-channel field-effect transistors, and complementary logic circuits. Rylene diimides are a robust, versatile class of polycyclic aromatic electron-transport materials with excellent thermal and oxidative stability, high electron affinities, and, in many cases, high electron mobilities; they are, therefore, promising candidates for a variety of organic electronics applications. In this review, recent developments in the area of high-electron-mobility diimides based on rylenes and related aromatic cores, particularly perylene- and naphthalene-diimide-based small molecules and polymers, for application in high-performance organic field-effect transistors and photovoltaic cells are summarized and analyzed.
TL;DR: To facilitate the application of graphene in nanodevices and to effectively tune the bandgap of graphenes, a promising approach is to convert the 2D graphene sheets into 0D graphene quantum dots (GQDs).
Abstract: Graphene, the two-dimensional (2D) single-atom carbon sheet, has attracted tremendous research interest due to its large surface area, high carrier transport mobility, superior mechanical fl exibility and excellent thermal/chemical stability. [ 1 ] In particular, its high transport mobility [ 2 , 3 ] and environmentally friendly nature meet important requirements in the fabrication of optoelectronic devices. Apart from the conducting fi lm [ 4 , 5 ] and transparent anode [ 6 ] developed previously, its high mobility renders it a promising alternative as an electron-accepting material for photovoltaic device applications. However, the easy aggregation and the poor dispersion of 2D graphene sheets in common solvents limit its application in such devices. Although effort has been made to prepare solution-processable functionalized graphenes (SPFGs), [ 7 ] the non-uniform size and shape, on a scale of several hundred nanometers and even micrometers of SPFGs, remain big challenges for the fabrication of highperformance photovoltaic cells with active layer thicknesses of only nanometer scale. To facilitate the application of graphene in nanodevices and to effectively tune the bandgap of graphenes, a promising approach is to convert the 2D graphene sheets into 0D graphene quantum dots (GQDs). Apart from unique electron transportation properties, [ 8 ] new phenomena from GQDs associated with quantum confi nement and edge effects are expected. [ 9 ] QDs are important for various applications in bioimaging, [ 10 ] lasing, [ 11 ]
TL;DR: BHJ solar cells are typically fabricated with a transparent conductive anode, a low-work-function metal cathode, and an active layer sandwiched between the anode and cathode.
Abstract: BHJ solar cells are typically fabricated with a transparent conductive anode (e.g. indium tin oxide, ITO), a low-work-function metal cathode (e.g., Al, Ca), and an active layer (a mixture of conjugated polymer and fullerene derivative) sandwiched between the anode and cathode. The BHJ layer and cathode dramatically affect the stability. In particular, the cathode is susceptible to degradation by oxygen and water vapor. Poly(3,4ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is often used as an anode buffer layer. Long-term stability is a problem because PEDOT:PSS is hygroscopic and acidic. [ 17–21 ]
TL;DR: Recent progress in functional materials applied in the currently prevailing rechargeable lithium-ion, nickel-metal hydride, lead acid, vanadium redox flow, and sodium-sulfur batteries is reviewed.
Abstract: There is an ever-growing demand for rechargeable batteries with reversible and efficient electrochemical energy storage and conversion. Rechargeable batteries cover applications in many fields, which include portable electronic consumer devices, electric vehicles, and large-scale electricity storage in smart or intelligent grids. The performance of rechargeable batteries depends essentially on the thermodynamics and kinetics of the electrochemical reactions involved in the components (i.e., the anode, cathode, electrolyte, and separator) of the cells. During the past decade, extensive efforts have been dedicated to developing advanced batteries with large capacity, high energy and power density, high safety, long cycle life, fast response, and low cost. Here, recent progress in functional materials applied in the currently prevailing rechargeable lithium-ion, nickel-metal hydride, lead acid, vanadium redox flow, and sodium-sulfur batteries is reviewed. The focus is on research activities toward the ionic, atomic, or molecular diffusion and transport; electron transfer; surface/interface structure optimization; the regulation of the electrochemical reactions; and the key materials and devices for rechargeable batteries.
TL;DR: This work has shown that materials presenting high pseudocapacitence (metal oxides) are incorporated directly into highly conductive nanostructured carbons (carbon nanotubes) in a manner similar to batteries, which enables high energy density but is in general kinetically unfavorable.
Abstract: With the ever-increasing power and energy needs in applications ranging from next-generation plug-in hybrid electric vehicles (PHEVs) and modern consumer electronics to microand nanoelectromechanical systems, recent research and development has focused on new electrode materials for advanced energy storage devices. [ 1–5 ] Of the various power source devices, supercapacitors, also known as electrochemical capacitors (ECs), have attracted great interest due to a number of desirable properties, including fast charging and discharging, long cycle life, and the ability to deliver up to ten times more power than conventional batteries. [ 6–10 ] In addition, ECs play an important role in complementing fuel cells in future all-electric vehicles based on clean and renewable energy media. [ 11 ] There are three major types of electrode materials reported for ECs: carbonaceous materials, [ 12 ] metal oxides/hydroxides, [ 13 ] and conducting polymers. [ 14 ] Carbon-based materials store charge electrostatically from the reversible adsorption of ions onto their surfaces, leading to high power delivery at the cost of low energy density. By contrast, metal oxides/hydroxides and conducting polymers store charge in a faradic or redox-type process similar to batteries, which enables high energy density but is in general kinetically unfavorable. To bridge the performance gap between these materials, attempts at novel electrode design have been extensively made. Despite a huge number of publications, nearly all of them can be clarifi ed into one general concept, that is, the use of pseudocapacitive material–conductive matrix hybrid nanostructures. [ 15 , 16 ] In this regard, materials presenting high pseudocapacitence (metal oxides) are incorporated directly into highly conductive nanostructured carbons (carbon nanotubes, [ 17–20 ]
TL;DR: Blue phosphorescence approaching the theoretical efficiency has also been achieved, which may overcome the final obstacle against the commercialization of full color display and white light sources from phosphorescent materials.
Abstract: Although organic light-emitting devices have been commercialized as flat panel displays since 1997, only singlet excitons were emitted. Full use of singlet and triplet excitons, electrophosphorescence, has attracted increasing attentions after the premier work made by Forrest, Thompson, and co-workers. In fact, red electrophosphorescent dye has already been used in sub-display of commercial mobile phones since 2003. Highly efficient green phosphorescent dye is now undergoing of commercialization. Very recently, blue phosphorescence approaching the theoretical efficiency has also been achieved, which may overcome the final obstacle against the commercialization of full color display and white light sources from phosphorescent materials. Combining light out-coupling structures with highly efficient phosphors (shown in the table-of-contents image), white emission with an efficiency matching that of fluorescent tubes (90 lm/W) has now been realized. It is possible to tune the color to the true white region by changing to a deep blue emitter and corresponding wide gap host and transporting material for the blue phosphor. In this article, recent progresses in red, green, blue, and white electrophosphorescent materials for OLEDs are reviewed, with special emphasis on blue electrophosphorescent materials.
TL;DR: This review covers advances in the MOF field from the past three years, focusing on applications, including gas separation, catalysis, drug delivery, optical and electronic applications, and sensing.
Abstract: Metal-organic frameworks (MOFs) represent a new class of hybrid organic-inorganic supramolecular materials comprised of ordered networks formed from organic electron donor linkers and metal cations. They can exhibit extremely high surface areas, as well as tunable pore size and functionality, and can act as hosts for a variety of guest molecules. Since their discovery, MOFs have enjoyed extensive exploration, with applications ranging from gas storage to drug delivery to sensing. This review covers advances in the MOF field from the past three years, focusing on applications, including gas separation, catalysis, drug delivery, optical and electronic applications, and sensing. We also summarize recent work on methods for MOF synthesis and computational modeling.
TL;DR: This Research News article is focused on a survey of the tremendous literature published between 2002 and 2010 that exhibits solar cells based on blends of P3HT and PCBM.
Abstract: In the field of polymer-based photovoltaic cells, poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C61 (PCBM) are, to date, the most-studied active materials around the world for the bulk-heterojunction structure. Various power-conversion efficiencies are reported up to approximately 5%. This Research News article is focused on a survey of the tremendous literature published between 2002 and 2010 that exhibits solar cells based on blends of P3HT and PCBM.
TL;DR: This book aims to provide a history of Tibet and its people from 1989 to 2002, a period chosen in order to explore its roots as well as specific cases up to and including the year in which descriptions of Tibetans in the region began to circulate.
Abstract: Ronan J. Smith , Paul J. King , Mustafa Lotya , Christian Wirtz , Umar Khan , Sukanta De , Arlene O’Neill , Georg S. Duesberg , Jaime C. Grunlan , Gregory Moriarty , Jun Chen , Jiazhao Wang , Andrew I. Minett , Valeria Nicolosi , and Jonathan N. Coleman *
TL;DR: This review highlights the recent progress in the chemical synthesis of bimetallic NCs and the control over morphology, size, composition, and structure of bimodal NCs as well as the exploration of their properties and applications.
Abstract: Bimetallic nanocrystals (NCs) with core/shell, heterostructure, or inter-metallic and alloyed structures are emerging as more important materials than monometallic NCs They are expected to display not only a combination of the properties associated with two distinct metals, but also new properties and capabilities due to a synergy between the two metals More importantly, bimetallic NCs usually show composition-dependent surface structure and atomic segregation behavior, and therefore more interesting applied potentials in various fields including electronics, engineering, and catalysis Compared with monometallic NCs, preparation of bimetallic NCs is much more complicated and difficult to be achieved In recent years, researchers from many groups have made great efforts in this area This review highlights the recent progress in the chemical synthesis of bimetallic NCs The control over morphology, size, composition, and structure of bimetallic NCs as well as the exploration of their properties and applications are discussed
TL;DR: A combination of extraordinary electrical, thermal, and mechanical properties makes graphene sheets not only attractive as atom-thick components in nanoelectronic devices, but also excellent molecular building blocks for assembling new macroscopic materials for widespread applications.
Abstract: A simple, bioinspired approach to effectively prevent the restacking of chemically converted graphene sheets in multilayered films is presented. The method enables the creation of a new generation of supercapacitors that combine high energy density, high power density, and high operation rates. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
TL;DR: This review will present how the bio-inspired wettability has been integrated into traditional materials or devices to improve their performances and to extend their practical applications by developing new functionalities.
Abstract: In this review we focus on recent developments in applications of bio-inspired special wettable surfaces. We highlight surface materials that in recent years have shown to be the most promising in their respective fields for use in future applications. The selected topics are divided into three groups, applications of superhydrophobic surfaces, surfaces of patterned wettability and integrated multifunctional surfaces and devices. We will present how the bio-inspired wettability has been integrated into traditional materials or devices to improve their performances and to extend their practical applications by developing new functionalities.
TL;DR: In this progress report, the recent advancements in the studies of the composites of CCG and small molecules, polymers, inorganic nanoparticles or other carbon nanomaterials are reviewed.
Abstract: Graphene, a one-atom layer of graphite, possesses a unique two-dimensional structure and excellent mechanical, thermal, and electrical properties. Thus, it has been regarded as an important component for making various functional composite materials. Graphene can be prepared through physical, chemical and electrochemical approaches. Among them, chemical methods were tested to be effective for producing chemically converted graphene (CCG) from various precursors (such as graphite, carbon nanotubes, and polymers) in large scale and at low costs. Therefore, CCG is more suitable for synthesizing high-performance graphene based composites. In this progress report, we review the recent advancements in the studies of the composites of CCG and small molecules, polymers, inorganic nanoparticles or other carbon nanomaterials. The methodology for preparing CCG and its composites has been summarized. The applications of CCG-based functional composite materials are also discussed.
TL;DR: Recent progress in the development of the most commonly used electronically conducting polymers used in flexible device prototypes are discussed, the advantages and disadvantages of this type of energy storage devices, as well as the two main approaches used in the manufacturing of paper-based charge storage devices.
Abstract: All-polymer and paper-based energy storage devices have significant inherent advantages in comparison with many currently employed batteries and supercapacitors regarding environmental friendliness, flexibility, cost and versatility. The research within this field is currently undergoing an exciting development as new polymers, composites and paper-based devices are being developed. In this report, we review recent progress concerning the development of flexible energy storage devices based on electronically conducting polymers and cellulose containing composites with particular emphasis on paper-based batteries and supercapacitors. We discuss recent progress in the development of the most commonly used electronically conducting polymers used in flexible device prototypes, the advantages and disadvantages of this type of energy storage devices, as well as the two main approaches used in the manufacturing of paper-based charge storage devices.
TL;DR: Recent studies on advanced ESIPT molecules and their optoelectronic applications are surveyed, particularly focusing on chemical sensors, fluorescence imaging, proton transfer lasers, and organic light-emitting diodes (OLEDs).
Abstract: Recently, organic fluorescent molecules harnessing the excited-state intramolecular proton transfer (ESIPT) process are drawing great attention due to their unique photophysical properties which facilitate novel optoelectronic applications. After a brief introduction to the ESIPT process and related photo-physical properties, molecular design strategies towards tailored emission are discussed in relation to their theoretical aspects. Subsequently, recent studies on advanced ESIPT molecules and their optoelectronic applications are surveyed, particularly focusing on chemical sensors, fluorescence imaging, proton transfer lasers, and organic light-emitting diodes (OLEDs).
TL;DR: While the fragility of superhydrophobic surfaces currently limits their applicability, development of mechanically durable surfaces will enable a wide range of new applications in the future.
Abstract: Development of durable non-wetting surfaces is hindered by the fragility of the microscopic roughness features that are necessary for superhydrophobicity. Mechanical wear on superhydrophobic surfaces usually shows as increased sticking of water, leading to loss of non-wettability. Increased wear resistance has been demonstrated by exploiting hierarchical roughness where nanoscale roughness is protected to some degree by large scale features, and avoiding the use of hydrophilic bulk materials is shown to help prevent the formation of hydrophilic defects as a result of wear. Additionally, self-healing hydrophobic layers and roughness patterns have been suggested and demonstrated. Nevertheless, mechanical contact not only causes damage to roughness patterns but also surface contamination, which shortens the lifetime of superhydrophobic surfaces in spite of the self-cleaning effect. The use of photocatalytic effect and reduced electric resistance have been suggested to prevent the accumulation of surface contaminants. Resistance to organic contaminants is more challenging, however, oleophobic surface patterns which are non-wetting to organic liquids have been demonstrated. While the fragility of superhydrophobic surfaces currently limits their applicability, development of mechanically durable surfaces will enable a wide range of new applications in the future.
TL;DR: A brief description of cancer pathology and the characteristics that are important for tumor‐targeted NM design are provided, followed by an overview of the different types of NMs explored to date, covering synthetic aspects and approaches explored.
Abstract: The application of nanomaterials (NMs) in biomedicine is increasing rapidly and offers excellent prospects for the development of new non-invasive strategies for the diagnosis and treatment of cancer. In this review, we provide a brief description of cancer pathology and the characteristics that are important for tumor-targeted NM design, followed by an overview of the different types of NMs explored to date, covering synthetic aspects and approaches explored for their application in unimodal and multimodal imaging, diagnosis and therapy. Significant synthetic advances now allow for the preparation of NMs with highly controlled geometry, surface charge, physicochemical properties, and the decoration of their surfaces with polymers and bioactive molecules in order to improve biocompatibility and to achieve active targeting. This is stimulating the development of a diverse range of nanometer-sized objects that can recognize cancer tissue, enabling visualization of tumors, delivery of anti-cancer drugs and/or the destruction of tumors by different therapeutic techniques.
TL;DR: The red-shift of emission independent of the size provides an insight into the luminescence mechanism of C-nanodots.
Abstract: The size of C-nanodots can be electrochemically tuned by changing the applied potential during their preparation. The higher the applied potential, the smaller the resulting C-nanodots. Moreover, the surface oxidation degree of the C-nanodots can also be electrochemically tuned. The red-shift of emission independent of the size provides an insight into the luminescence mechanism of C-nanodots.
TL;DR: A route for the preparation of binder-free sulfur-carbon cathodes is developed for lithium sulfur batteries that demonstrate good electrochemical performance at high current density attributed to the uniform dispersion of sulfur inside the carbon fiber.
Abstract: A route for the preparation of binder-free sulfur-carbon cathodes is developed for lithium sulfur batteries. The method is based on the impregnation of elemental sulfur into the micropores of activated carbon fibers. These electrodes demonstrate good electrochemical performance at high current density attributed to the uniform dispersion of sulfur inside the carbon fiber.