Spontaneous Curvature Induction in an Artificial Bilayer Membrane.

Maintaining lipid asymmetry across membrane leaflets is critical for functions like vesicular traffic and organelle homeostasis. However, a lack of molecular-level understanding of the mechanisms underlying membrane fission and fusion processes in synthetic systems precludes their development as artificial analogs. Here, we report asymmetry induction of a bilayer membrane formed by an extended π-conjugated molecule with oxyalkylene side chains bearing terminal tertiary amine moieties (BA1) in water. Autogenous protonation of the tertiary amines in the periphery of the bilayer by water induces anisotropic curvature, resulting in membrane fission to form vesicles and can be monitored using time-dependent spectroscopy and microscopy. Interestingly, upon loss of the induced asymmetry by extensive protonation using an organic acid restored bilayer membrane. The mechanism leading to the compositional asymmetry in the leaflet and curvature induction in the membrane is validated by density functional theory (DFT) calculations. Studies extended to control molecules having changes in hydrophilic (BA2) and hydrophobic (BA3) segments provide insight into the delicate nature of molecular scale interactions in the dynamic transformation of supramolecular structures. The synergic effect of hydrophobic interaction and the hydrated state of BA1 aggregates provide dynamicity and unusual stability. Our study unveils mechanistic insight into the dynamic transformation of bilayer membranes into vesicles.

Recent Progress of 2D Layered Materials in Water-in-Salt/Deep Eutectic Solvent-Based Liquid Electrolytes for Supercapacitors.

Supercapacitors are candidates with the greatest potential for use in sustainable energy resources. Extensive research is being carried out to improve the performances of state-of-art supercapacitors to meet our increased energy demands because of huge technological innovations in various fields. The development of high-performing materials for supercapacitor components such as electrodes, electrolytes, current collectors, and separators is inevitable. To boost research in materials design and production toward supercapacitors, the up-to-date collection of recent advancements is necessary for the benefit of active researchers. This review summarizes the most recent developments of water-in-salt (WIS) and deep eutectic solvents (DES), which are considered significant electrolyte systems to advance the energy density of supercapacitors, with a focus on two-dimensional layered nanomaterials. It provides a comprehensive survey of 2D materials (graphene, MXenes, and transition-metal oxides/dichalcogenides/sulfides) employed in supercapacitors using WIS/DES electrolytes. The synthesis and characterization of various 2D materials along with their electrochemical performances in WIS and DES electrolyte systems are described. In addition, the challenges and opportunities for the next-generation supercapacitor devices are summarily discussed.

Optimization of acetamide based deep eutectic solvents with dual cations for high performance and low temperature-tolerant aqueous zinc ion batteries via tuning the ratio of co-solvents.

In this work, a novel acetamide-based deep eutectic solvent (DES) with Zn2+/ Li+ dual ions is designed and its physicochemical properties are tuned by adjusting the co-solvents (water and acetonitrile). Furthermore, the interplay between electrolyte components is investigated by spectroscopic analyses and molecular dynamics calculations. The addition of acetonitrile facilitates the formation of solid electrolyte interphase (SEI) with organic/inorganic components on the zinc anode. The presence of SEI coating enhances Coulombic efficiency and cycling stability by inhibiting the parasitic reactions and dendrite formation in the anode. The advantages of using dual cations in DES are demonstrated by assembling Zn ion batteries (ZIB) with the composite of δ-MnO2 and reduced graphene oxide as the cathode. The study of electrode kinetics in hybrid DES electrolytes suggests that Zn2+ and Li+ ions are responsible for battery-like and pseudocapacitive behavior of δ-MnO2 electrodes, respectively. With these merits, ZIB with the cutoff voltage of 2 V delivers a high cell capacity of 208 mAh g-1 at 0.1 Ag-1 and achieves 91% capacity retention after 1500 cycles at 2 Ag-1. More importantly, ZIB with hybrid DES is stably operated at the temperature of -20 °C, which is impossibly achieved by ZIB with conventional aqueous electrolytes.

Recent Advances in the Development of Lipid-, Metal-, Carbon-, and Polymer-Based Nanomaterials for Antibacterial Applications.

Infections caused by multidrug-resistant (MDR) bacteria are becoming a serious threat to public health worldwide. With an ever-reducing pipeline of last-resort drugs further complicating the current dire situation arising due to antibiotic resistance, there has never been a greater urgency to attempt to discover potential new antibiotics. The use of nanotechnology, encompassing a broad range of organic and inorganic nanomaterials, offers promising solutions. Organic nanomaterials, including lipid-, polymer-, and carbon-based nanomaterials, have inherent antibacterial activity or can act as nanocarriers in delivering antibacterial agents. Nanocarriers, owing to the protection and enhanced bioavailability of the encapsulated drugs, have the ability to enable an increased concentration of a drug to be delivered to an infected site and reduce the associated toxicity elsewhere. On the other hand, inorganic metal-based nanomaterials exhibit multivalent antibacterial mechanisms that combat MDR bacteria effectively and reduce the occurrence of bacterial resistance. These nanomaterials have great potential for the prevention and treatment of MDR bacterial infection. Recent advances in the field of nanotechnology are enabling researchers to utilize nanomaterial building blocks in intriguing ways to create multi-functional nanocomposite materials. These nanocomposite materials, formed by lipid-, polymer-, carbon-, and metal-based nanomaterial building blocks, have opened a new avenue for researchers due to the unprecedented physiochemical properties and enhanced antibacterial activities being observed when compared to their mono-constituent parts. This review covers the latest advances of nanotechnologies used in the design and development of nano- and nanocomposite materials to fight MDR bacteria with different purposes. Our aim is to discuss and summarize these recently established nanomaterials and the respective nanocomposites, their current application, and challenges for use in applications treating MDR bacteria. In addition, we discuss the prospects for antimicrobial nanomaterials and look forward to further develop these materials, emphasizing their potential for clinical translation.

Solid and Liquid Surface-Supported Bacterial Membrane Mimetics as a Platform for the Functional and Structural Studies of Antimicrobials.

Increasing antibiotic resistance has provoked the urgent need to investigate the interactions of antimicrobials with bacterial membranes. The reasons for emerging antibiotic resistance and innovations in novel therapeutic approaches are highly relevant to the mechanistic interactions between antibiotics and membranes. Due to the dynamic nature, complex compositions, and small sizes of native bacterial membranes, bacterial membrane mimetics have been developed to allow for the in vitro examination of structures, properties, dynamics, and interactions. In this review, three types of model membranes are discussed: monolayers, supported lipid bilayers, and supported asymmetric bilayers; this review highlights their advantages and constraints. From monolayers to asymmetric bilayers, biomimetic bacterial membranes replicate various properties of real bacterial membranes. The typical synthetic methods for fabricating each model membrane are introduced. Depending on the properties of lipids and their biological relevance, various lipid compositions have been used to mimic bacterial membranes. For example, mixtures of phosphatidylethanolamines (PE), phosphatidylglycerols (PG), and cardiolipins (CL) at various molar ratios have been used, approaching actual lipid compositions of Gram-positive bacterial membranes and inner membranes of Gram-negative bacteria. Asymmetric lipid bilayers can be fabricated on solid supports to emulate Gram-negative bacterial outer membranes. To probe the properties of the model bacterial membranes and interactions with antimicrobials, three common characterization techniques, including quartz crystal microbalance with dissipation (QCM-D), surface plasmon resonance (SPR), and neutron reflectometry (NR) are detailed in this review article. Finally, we provide examples showing that the combination of bacterial membrane models and characterization techniques is capable of providing crucial information in the design of new antimicrobials that combat bacterial resistance.

Coassembled Nitric Oxide-Releasing Nanoparticles with Potent Antimicrobial Efficacy against Methicillin-Resistant Staphylococcus aureus (MRSA) Strains.

Nitric oxide (NO)-releasing nanoparticles are effective nanomedicines with diverse therapeutic advantages compared with small molecule-based NO donors. Here, we report a new class of furoxan-based NO-releasing nanoparticles using a simple, creative yet facile coassembly approach. This is the first time we demonstrated that the coassembled NO-releasing nanoparticles with poly(ethylene glycol)101-block-poly(propylene glycol)56-block-poly(ethylene glycol)101 (Pluronic F127) had potent antimicrobial efficacies against methicillin-resistant Staphylococcus aureus (MRSA) strains. Nanoparticles obtained from the coassembly of either 4-(1-(3-methylpentan-5-ol)oxyl)(3-phenylsulfonyl) furoxan (compound 1) or 4-methoxy(3-phenylsulfonyl) furoxan (compound 2) with Pluronic F127 exhibit 4-fold improved antimicrobial activities compared to their self-assembled counterparts without Pluronic F127. 5(6)-Carboxylfluorescein (CF) leakage experiments further reveal that both coassembled NO-releasing nanoparticles show stronger interactions with lipid bilayers than those self-assembled alone. Subsequently, their strong plasma membrane-damaging capabilities are confirmed under both high-resolution optical microscopy and scanning electron microscopy characterizations. This coassembly approach could be readily applied to other small molecule-based antimicrobials, providing new solutions and important insights to further antimicrobial recipe design.

Molecularly engineered organic copolymers as high capacity cathode materials for aqueous proton battery operating at sub-zero temperatures.

High-performance aqueous all-organic rechargeable batteries are promising candidates for cost-effective, safe, and environment-friendly next-generation energy storage devices. Herein, two organic copolymers with nanorod-like morphology (AN-TA, and AN-PA), composed of different tertiary amines, are synthesized as the cathode material for an aqueous proton battery. The individual copolymer electrodes possess the dominated diffusion-controlled electrode kinetics resulting from the proton insertion/de-insertion along with the surface-controlled processes in 2 M HCl and 2 M H2SO4. Among the two copolymers, AN-PA exhibits the maximum specific capacity of 145 mAh g-1 at 1 A g-1 and then, even at the higher current density of 10 A g-1, it possesses the capacity as 110 mAh g-1 in 2 M HCl. The assembled aqueous proton battery comprising of AN-PA as a cathode delivers the capacity of 80 mAh g-1 at 1 A g-1 in 2 M HCl. The maximum deliverable energy density of 33.9 Wh kg-1 is achieved at the power density of 423 W kg-1. Notably, our proton battery can well operate at the sub-zero temperature of -25 °C with a cell voltage of 1.1 V. More importantly, the device retains 84 % of the initial capacity after 1000 cycles at 2 A g-1 and exhibits the retention of specific capacity of about > 93% when compared to that of room temperature.

Fluoride-incorporated cobalt-based electrocatalyst towards enhanced hydrogen evolution reaction.

We report an electrocatalyst, Co bases (metallic Co and Co(OH)2) with fluoride-incorporated CoO coating on the surface of (CoO-F/Co), was synthesized by the electro-deposition method. The porous network architecture of CoO-F/Co on the glassy carbon electrode exhibited an ultra-low overpotential of 15 mV, achieving the geometric current density of 10 mA cm-2 in 1.0 M KOH, which were comparable with the HER performance of numerous reported noble metal electrocatalysts. It is demonstrated that fluoride incorporation improved the electrodeposition particle size, electronic density, conductivity and hydrophilicity of CoO-F/Co the HER performance.

A 1.9-V all-organic battery-supercapacitor hybrid device with high rate capability and wide temperature tolerance in a metal-free water-in-saltelectrolyte.

Developing battery-supercapacitor hybrid devices (BSHs) is viewed as an efficient route to shorten the gap between supercapacitors and batteries. In this study, a composite hydrogel consisting of perylene tetracarboxylic diimide (PTCDI) and reduced graphene oxide (rGO) is tested as the anode for BSHs in the electrolyte of ammonium acetate (NH4Ac) with a record concentration of 32 molality (m). This water-in-salt electrolyte exhibits a wide electrochemical stability window of 2.13 V and high conductivity of 23.3 mS cm-1 even at -12 °C. Molecular dynamics calculations and spectroscopic measurements reveal that a favorable water-acetate interaction occurs in a high concentration NH4Ac electrolyte. On the other hand, the study of electrode kinetics in 32 m NH4Ac demonstrates a high capacitive contribution to charge storage in PTCDI-rGO although an electrode redox reaction involves reversible enolization of carbonyl groups in PTCDI. This result suggests fast NH4+-ion intercalation kinetics in charge-discharge processes. Furthermore, the electrode performance is improved by optimizing the loading amount of rGO in composites. The best-performing composite electrode delivers the maximum capacity of 165 mAh g-1 at 0.5 A g-1 and sustains a great capacity retention of 66% at 8 A g-1. Finally, an all-organic BSH device is tested in a broad temperature window from -20 to 50 °C and is well operated at 1.9 V regardless of operating temperatures. Due to the synergetic effect of splendid electrolyte properties and high anode capacities, BSH devices possess the maximum energy density of 12.9 Wh kg-1 at the power density of 827 W kg-1 and retain 74 % of the initial capacity after 3000 cycles at 1 A g-1. Our study paves a novel route towards designing inexpensive and environmentally friendly BSH devices with high performances.

Electrodeposited NiSe on a forest of carbon nanotubes as a free-standing electrode for hybrid supercapacitors and overall water splitting.

NiSe nanoparticles are electrodeposited over a forest of carbon nanotubes (CNTs) to form an intertwined and porous network. The assynthesized composite (denoted as CNT@NiSe/SS) is used as a free-standing and multifunctional electrode for bothsupercapacitorsand overallwater splitting applications. For a supercapacitor application, CNT@NiSe/SS exhibits higher specific capacity and improved rate capability compared with individual NiSe and CNTs. A hybrid supercapacitor device consisting of battery-like CNT@NiSe/SS and EDLC-like graphene delivers a maximum energy density of 32.1 Wh kg-1 at a power density of 823 W kg-1 and has excellent stability after a floating test of 50 h. On the other hand, CNT@NiSe/SS also serves as a bifunctional electrocatalyst with high activity for overall water splitting. The CNT@NiSe/SS electrode displays excellent hydrogen and oxygen evolution reaction performance with the lowest overpotential of 174 mV at 10 mA cm-2 and 267 mV at 50 mA cm-2, respectively. The symmetrical two-electrode system requires an operating potential of 1.71 V to achieve a current density of 10 mA cm-2. Furthermore, this electrolyzer shows a negligible increment in potential after 24 hof continuouswater splitting. The outstanding performances of CNT@NiSe/SS can be attributed to the synergistic effect of NiSe and CNTs.

Annexin V-containing cubosomes for targeted early detection of apoptosis in degenerative retinal tissue.

New drug delivery materials targeting damaged ocular tissues are of particular interest. In this work, we have formulated annexin/phosphatidylserine/phytantriol and annexin/phosphatidylserine/monoolein cubosomes based on incorporation of 1,2-dipalmitoyl-sn-glycero-3-phospho-l-serine (PS) lipid and annexin V (ANX) protein with phytantriol (Phy) and monoolein (MO) respectively. The incorporation of ANX is important because it can be used as a diagnostic tool for in vivo apoptosis detection due to its high affinity to phosphatidylserine in the presence of Ca2+. We have also prepared PS-Phy and PS-MO cubosomes without ANX as a comparison, and characterized them using dynamic light scattering, cryo-TEM images and small-angle X-ray scattering, showing that PS-Phy cubosomes have greater chemical stability, and that ANX-PS-Phy cubosomes have the potential for in vivo drug delivery. In addition, we have reconstituted an apoptotic biomimetic membrane on a surface to gain insights into cubosome-bilayer interactions using a quartz-crystal microbalance and neutron reflectometry. The neutron reflectivity data reveal that there is exchange of materials between the biomimetic apoptotic bilayer and ANX-PS-Phy cubosomes, with an accumulation of ANX between the membrane and cubosomes possibly being the reason for the reduced cytotoxicity of ANX-PS-Phy cubosomes. A rat model of laser-induced choroidal neovascularization showed that ANX-PS-Phy cubosomes specifically targeted apoptotic cells in vivo. We propose that ANX-PS-Phy cubosomes are a potential candidate for ocular drug delivery for eye diseases.

Intraocular Pressure Induced Retinal Changes Identified Using Synchrotron Infrared Microscopy.

Infrared (IR) spectroscopy has been used to quantify chemical and structural characteristics of a wide range of materials including biological tissues. In this study, we examined spatial changes in the chemical characteristics of rat retina in response to intraocular pressure (IOP) elevation using synchrotron infrared microscopy (SIRM), a non-destructive imaging approach. IOP elevation was induced by placing a suture around the eye of anaesthetised rats. Retinal sections were collected onto transparent CaF2 slides 10 days following IOP elevation. Using combined SIRM spectra and chemical mapping approaches it was possible to quantify IOP induced changes in protein conformation and chemical distribution in various layers of the rat retina. We showed that 10 days following IOP elevation there was an increase in lipid and protein levels in the inner nuclear layer (INL) and ganglion cell layer (GCL). IOP elevation also resulted in an increase in nucleic acids in the INL. Analysis of SIRM spectra revealed a shift in amide peaks to lower vibrational frequencies with a more prominent second shoulder, which is consistent with the presence of cell death in specific layers of the retina. These changes were more substantial in the INL and GCL layers compared with those occurring in the outer nuclear layer. These outcomes demonstrate the utility of SIRM to quantify the effect of IOP elevation on specific layers of the retina. Thus SIRM may be a useful tool for the study of localised tissue changes in glaucoma and other eye diseases.

Effect of Lipid-Based Nanostructure on Protein Encapsulation within the Membrane Bilayer Mimetic Lipidic Cubic Phase Using Transmembrane and Lipo-proteins from the Beta-Barrel Assembly Machinery.

A fundamental understanding of the effect of amphiphilic protein encapsulation on the nanostructure of the bicontinuous cubic phase is crucial to progressing biomedical and biological applications of these hybrid protein-lipid materials, including as drug delivery vehicles, as biosensors, biofuel cells and for in meso crystallization. The relationship between the lipid nanomaterial and the encapsulated protein, however, remains poorly understood. In this study, we investigated the effect of incorporating the five transmembrane and lipo-proteins which make up the ß-barrel assembly machinery from Gram-negative bacteria within a series of bicontinuous cubic phases. The transmembrane ß-barrel BamA caused an increase in lattice parameter of the cubic phase upon encapsulation. By contrast, the mainly hydrophilic lipo-proteins BamB-E caused the cubic phase lattice parameters to decrease, despite their large size relative to the diameter of the cubic phase water channels. Analysis of the primary amino acid sequence was used to rationalize this effect, based on specific interactions between aromatic amino acids within the proteins and the polar-apolar interface. Other factors that were found to have an effect were lateral bilayer pressure and rigidity within the lipid bilayer, water channel diameter, and size and structure of the lipo-proteins. The data presented suggest that hydrophilic bioactive molecules can be selectively encapsulated within the cubic phase by using a lipid anchor or aromatic amino acids, for drug delivery or biosensing applications.

Reversible Association of Nitro Compounds with p-Nitrothiophenol Modified on Ag Nanoparticles/Graphene Oxide Nanocomposites through Plasmon Mediated Photochemical Reaction.

Because localized surface plasmon resonance in nanostructures of noble metals is accompanied by interesting physical effects such as optical near-field enhancement, heat release, and the generation of hot electrons, it has been employed in a wide range of applications, including plasmon-assisted chemical reactions. Here, we use a composite of silver nanoparticles and graphene oxide (Ag@GO) as the catalytic as well as the analytic platform for plasmon-assisted chemical reactions. Through time-dependent surface-enhanced Raman scattering experiments, it is found that p-nitrothiophenol (pNTP) molecules on Ag@GO can be associated with nitro compounds such as nitrobenzene and 1-nitropropane to form azo compounds when aided by the plasmons. Furthermore, the reaction rate can be modulated by varying the wavelength and power of the excitation laser as well as the nitro compounds used. In addition, the aforementioned coupling reaction can be reversed. We demonstrate that the oxidation of azo compounds on Ag@GO using KMnO4 leads to the dissociation of the N═N double bond in the azo compounds and that the rate of bond dissociation can be accelerated significantly via laser irradiation. Furthermore, the pNTP molecules on Ag@GO can be recovered after the oxidation reaction. Finally, we demonstrate that the plasmon-assisted coupling reaction allows for the immobilization of nitro-group-containing fluorophores at specific locations on Ag@GO.

Defining the structural characteristics of annexin V binding to a mimetic apoptotic membrane.

Annexin V is of crucial importance for detection of the phosphatidylserine of apoptotic cell membranes. However, the manner in which different amounts of phosphatidylserine at the membrane surface at different stages of apoptosis contribute to binding of annexin V is unclear. We have used a quartz crystal microbalance combined with dissipative monitoring (QCM-D) and neutron reflectivity to characterize binding of human annexin V to supported bilayers of different phospholipid composition. We created model apoptotic bilayers of 1-palmitoyl-2-oleoyl-sn-glycerophosphocholine and 1-palmitoyl-2-oleoyl-sn-glycerophosphoserine (POPS) in the ratios 19:1, 9:1, 6.7:1, 4:1, 3:1, and 2:1 (w/w) in the presence of 2.5 mM CaCl2. QCM-D data revealed that annexin V bound less to supported fluid lipid bilayers with higher POPS content (>25 % POPS). Neutron reflectivity was used to further characterize the detailed composition of lipid bilayers with membrane-bound annexin V. Analysis confirmed less annexin V binding with higher POPS content, that bound annexin V formed a discrete layer above the lipid bilayer with little effect on the overall structure of the membrane, and that the thickness and volume fraction of the annexin V layer varied with POPS content. From these results we show that the POPS content of the outer surface of lipid bilayers affects the structure of membrane-bound annexin V.

Nanocarriers for treatment of ocular neovascularization in the back of the eye: new vehicles for ophthalmic drug delivery.

Pathologic neovascularization of the retina is a major cause of substantial and irreversible loss of vision. Drugs are difficult to deliver to the lesions in the back of the eye and this is a major obstacle for the therapeutics. Current pharmacological approach involves an intravitreal injection of anti-VEGF agents to prevent aberrant growth of blood vessels, but it has limitations including therapeutic efficacy and side-effects associated with systemic exposure and invasive surgery. Nanotechnology provides novel opportunities to overcome the limitations of conventional delivery system to reach the back of the eye through fabrication of nanostructures capable of encapsulating and delivering small molecules. This review article introduces various forms of nanocarrier that can be adopted by ocular drug delivery systems to improve current therapy. The application of nanotechnology in medicine brings new hope for ocular drug delivery in the back of the eye to manage the major causes of blindness associated with ocular neovascularization.

Surface-enhanced Raman spectroscopy for DNA detection by the self-assembly of Ag nanoparticles onto Ag nanoparticle-graphene oxide nanocomposites.

A novel surface-enhanced Raman scattering (SERS) sensing system which operates by the self-assembly of Ag nanoparticles (AgNPs) onto the nanocomposite of AgNPs and graphene oxide (AgNP-GO) in the presence of two complementary DNAs has been developed. In this system, AgNP-GO serves as a SERS-active substrate. The AgNPs with the modification of non-fluorescent 4-mercaptobenzoic acid (4-MBA) act as highly efficient Raman probes for DNA hybridization. When probe DNAs on AgNP-GO are complementary to target DNAs on AgNPs functionalized with 4-MBA, the DNA hybridization occurring directs the self-assembly of AgNPs onto AgNP-GO, leading to the creation of SERS hot spots. Due to the fact that partial 4-MBA molecules are located in the region of the hot spots, their SERS signals are greatly enhanced, indicating successful DNA hybridization. It is noteworthy that the size of AgNPs contributes significantly to the enhancement of SERS activity. The detection limit of the target DNAs at the pM level can be achieved through the self-assembly of large sized AgNPs onto AgNP-GO. More importantly, the AgNP-AgNP-GO system shows reproducible SERS signals in proportion to the logarithm of the target DNA concentrations spanning from 10(-6) to 10(-12) M and the excellent capability for multiplex DNA detection.

High energy density asymmetric supercapacitor based on NiOOH/Ni3S2/3D graphene and Fe3O4/graphene composite electrodes.

The application of the composite of Ni3S2 nanoparticles and 3D graphene as a novel cathode material for supercapacitors is systematically investigated in this study. It is found that the electrode capacitance increases by up to 111% after the composite electrode is activated by the consecutive cyclic voltammetry scanning in 1 M KOH. Due to the synergistic effect, the capacitance and the diffusion coefficient of electrolyte ions of the activated composite electrode are ca. 3.7 and 6.5 times higher than those of the Ni3S2 electrode, respectively. Furthermore, the activated composite electrode exhibits an ultrahigh specific capacitance of 3296 F/g and great cycling stability at a current density of 16 A/g. To obtain the reasonable matching of cathode/anode electrodes, the composite of Fe(3)O(4) nanoparticles and chemically reduced graphene oxide (Fe(3)O(4)/rGO) is synthesized as the anode material. The Fe(3)O(4)/rGO electrode exhibits the specific capacitance of 661 F/g at 1 A/g and excellent rate capability. More importantly, an asymmetric supercapacitor fabricated by two different composite electrodes can be operated reversibly between 0 and 1.6 V and obtain a high specific capacitance of 233 F/g at 5 mV/s, which delivers a maximum energy density of 82.5 Wh/kg at a power density of 930 W/kg.

Hierarchically structured Ni(3)S(2)/carbon nanotube composites as high performance cathode materials for asymmetric supercapacitors.

The Ni3S2 nanoparticles with the diameters ranging from 10 to 80 nm are grown on the backbone of conductive multiwalled carbon nanotubes (MWCNTs) using a glucose-assisted hydrothermal method. It is found that the Ni3S2 nanoparticles deposited on MWCNTs disassemble into smaller components after the composite electrode is activated by the consecutive cyclic voltammetry scan in a 2 M KOH solution. Therefore, the active surface area of the Ni3S2 nanoparticles is increased, which further enhances the capacitive performance of the composite electrode. Because the synergistic effect of the Ni3S2 nanoparticles and MWCNTs on the capacitive performance of the composite electrode is pronounced, the composite electrode shows a high specific capacitance of 800 F/g and great cycling stability at a current density of 3.2 A/g. To examine the capacitive performance of the composite electrode in a full-cell configuration, an asymmetric supercapacitor device was fabricated by using the composite of Ni3S2 and MWCNTs as the cathode and activated carbon as the anode. The fabricated device can be operated reversibly between 0 and 1.6 V, and obtain a high specific capacitance of 55.8 F/g at 1 A/g, which delivers a maximum energy density of 19.8 Wh/kg at a power density of 798 W/kg. Furthermore, the asymmetric supercapacitor shows great stability based on the fact that the device retains 90% of its initial capacitance after a consecutive 5000 cycles of galvanostatic charge-discharge performed at a current density of 4 A/g.

Synthesis of large-area MoS2 atomic layers with chemical vapor deposition.

Large-area MoS(2) atomic layers are synthesized on SiO(2) substrates by chemical vapor deposition using MoO(3) and S powders as the reactants. Optical, microscopic and electrical measurements suggest that the synthetic process leads to the growth of MoS(2) monolayer. The TEM images verify that the synthesized MoS(2) sheets are highly crystalline.