Synthesis of tubular nanomaterials has become a prolific area of investigation due to their wide range of applications. A
facile solution-based method has been designed to fabricate uniform Bi2S3 nanotubes with average size of 20 nm × 160 nm using only bismuth nitrate (Bi(NO3)3·5H2O) and sulfur powder (S) as the reactants and octadecylamine (ODA) as the solvent. Powder X-ray diffraction (XRD), transmission
electron microscopy (TEM), high-resolution TEM (HRTEM), and energy dispersive spectroscopy (EDX) experiments were employed
to characterize the resulting Bi2S3 nanotubes and the classic rolling mechanism was applied to explain their formation process.
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Inorganic fullerene-like WS2 and MoS2 nanoparticles have been synthesized using exclusively solid precursors, by reaction of the corresponding metal oxide nanopowder,
sulfur and a hydrogen-releasing agent (NaBH4 or LiAlH4), achieved either by conventional furnace heating up to ∼900 °C or by photothermal ablation at far higher temperatures driven
by highly concentrated white light. In contrast to the established syntheses that require toxic and hazardous gases, working
solely with solid precursors permits relatively safer reactor conditions conducive to industrial scale-up.
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Submicrometer sized pure cubic phase, Eu3+ doped, and Yb3+/Er3+ co-doped α-NaYF4 particles with octahedral morphology have been prepared in acetic acid. The acetate anion plays a critical role in the formation
of such symmetric octahedral structures through its selective adsorption on the (111) faces of the products. The size of the
as-prepared octahedra can be tuned by varying the amount of sodium acetate added to the acetic acid. A possible formation
mechanism for these octahedra has been proposed. The doped α-NaYF4 octahedral submicrometer particles show down-conversion and up-conversion photoluminescence typical of these materials.
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Two fluorescent quantum clusters of gold, namely Au25 and Au8, have been synthesized from mercaptosuccinic acid-protected gold nanoparticles of 4–5 nm core diameter by etching with excess
glutathione. While etching at pH ∼3 yielded Au25, that at pH 7–8 yielded Au8. This is the first report of the synthesis of two quantum clusters starting from a single precursor. This simple method makes
it possible to synthesize well-defined clusters in gram quantities. Since these clusters are highly fluorescent and are highly
biocompatible due to their low metallic content, they can be used for diagnostic applications.
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A novel lamellar feather-like CeO2 structure has been fabricated by using a triblock copolymer as the structure-directing agent. This material was characterized
in detail by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy,
and BET surface area measurements. Compared with conventional spherical shaped ceria prepared by ammonia gelation, the ceria
feathers have superior ability to support nanosized platinum particles due to their special structure. The “skeletons” of
ceria feathers can serve as an ideal host matrix to anchor the platinum particles. Furthermore, the inter-crossing pattern
of the “skeletons” also acts as a partition to separate platinum particles, allowing the Pt nanoparticles (average diameter
∼6 nm) to be highly dispersed in the structure. The Pt/feather-like CeO2 catalyst exhibits high activity in the water gas shift reaction.
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We propose a simple method for the efficient and rapid synthesis of one-dimensional hematite (α-Fe2O3) nanostructures based on electrical resistive heating of iron wire under ambient conditions. Typically, 1–5 μm long α-Fe2O3 nanowires were synthesized on a time scale of seconds at temperatures of around 700 ° ⊂. The morphology, structure, and mechanism
of formation of the nanowires were studied by scanning and transmission electron microscopies, energy dispersive X-ray spectroscopy,
X-ray photoelectron spectroscopy, and Raman techniques. A nanowire growth mechanism based on diffusion of iron ions to the
surface through grain boundaries and to the growing wire tip through stacking fault defects and due to surface diffusion is
proposed.
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This paper describes a facile method of preparing cubic Au nanoframes with open structures via the galvanic replacement reaction
between Ag nanocubes and AuCl2−. A mechanistic study of the reaction revealed that the formation of Au nanoframes relies on the diffusion of both Au and
Ag atoms. The effect of the edge length and ridge thickness of the nanoframes on the localized surface plasmon resonance peak
was explored by a combination of discrete dipole approximation calculations and single nanoparticle spectroscopy. With their
hollow and open structures, the Au nanoframes represent a novel class of substrates for applications including surface plasmonics
and surface-enhanced Raman scattering.
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Shape control of nanocrystals has become a significant subject in materials science. In this work, we describe a convenient
way to achieve morphology-controllable synthesis of CoO nanocrystals including octahedrons and spheres as well as LiCoO2 polyhedrons and spheres. In particular, we explain the formation of CoO octahedrons exposing only high-energy (111) facets
using theoretical calculations; these should also be a useful tool for directing future face-controlled preparation of other
nanocrystals. More importantly, the as-obtained LiCoO2 nanocrystals showed different electrochemical performance depending on their morphology, indicating that Li-insertion/deintercalation
dynamics might be crystal face-sensitive.
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Uniform colloidal Bi2S3 nanodots and nanorods with different sizes have been prepared in a controllable manner via a hot injection method. X-ray
diffraction (XRD) results show that the resulting nanocrystals have an orthorhombic structure. Both the diameter and length
of the nanorods increase with increasing concentration of the precursors. All of the prepared Bi2S3 nanostructures show high efficiency in the photodegradation of rhodamine B, especially in the case of small sized nanodots—which
is possibly due to their high surface area. The dynamics of the photocatalysis is also discussed.
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High quality InAs/InP/ZnSe core/shell/shell quantum dots have been grown by a one-pot approach. This engineered quantum dots
with unique near-infrared (NIR) fluorescence, possessing outstanding optical properties, and the biocompatibility desired
for in vivo applications. The resulting quantum dots have significantly lower intrinsic toxicity compared to NIR emissive
dots containing elements such as cadmium, mercury, or lead. Also, these newly developed ultrasmall non-Cd containing and NIR-emitting
quantum dots showed significantly improved circulation half-life and minimal reticuloendothelial system (RES) uptake.
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Films of Ni1−xPtx (x=0, 0.02, 0.04, 0.06, and 0.08) have been prepared on fluorine-doped tin oxide-coated (FTO) glass substrates by a chemical
plating method and used as the photocathode for dye-sensitized solar cells (DSCs). The Ni0.94Pt0.06 film consisted of nanoparticles with a size of 4–6 nm and a Pt loading of 5.13 μg/cm2. The Ni0.94Pt0.06 photocathode exhibited high catalytic performance toward triiodide reduction, high light reflectance, and low charge-transfer
resistance. The DSC assembled with the Ni0.94Pt0.06 photocathode gave a short-circuit photocurrent density (Jsc) of 16.79 mA/cm2, an open-circuit photovoltage (Voc) of 736 mV, and a fill factor (FF) of 66.4%, corresponding to an overall conversion efficiency of 8.21% under standard AM
1.5 irradiation (100 mW/cm2), which is higher than that for the DSC with a pure Pt photocathode obtained by conventional thermal decomposition. Furthermore,
the DSC based on the Ni0.94Pt0.06 photocathode showed good stability. The results indicate that Ni0.94Pt0.06 films are promising lowcost and high-performance photocathodes for use in DSCs.
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Emerging layered semiconductors present multiple advantages for optoelectronic technologies including high carrier mobilities, strong light-matter interactions, and tunable optical absorption and emission. Here, metal-semiconductor-metal avalanche photodiodes (APDs) are fabricated from Bi2O2Se crystals, which consist of electrostatically bound [Bi2O2]2+ and [Se]2− layers. The resulting APDs possess an intrinsic carrier multiplication factor up to 400 at 7 K with a responsivity gain exceeding 3,000 A/W and bandwidth of ~ 400 kHz at a visible wavelength of 515.6 nm, ultimately resulting in a gain bandwidth product exceeding 1 GHz. Due to exceptionally low dark currents, Bi2O2Se APDs also yield high detectivities up to 4.6 × 1014 Jones. A systematic analysis of the photocurrent temperature and bias dependence reveals that the carrier multiplication process in Bi2O2Se APDs is consistent with a reverse biased Schottky diode model with a barrier height of ~ 44 meV, in contrast to the charge trapping extrinsic gain mechanism that dominates most layered semiconductor phototransistors. In this manner, layered Bi2O2Se APDs provide a unique platform that can be exploited in a diverse range of high-performance photodetector applications.
We report the investigation of the thermoelectric properties of large-scale solution-synthesized Bi2Te3 nanocomposites prepared from nanowires hotpressed into bulk pellets. A third element, Se, is introduced to tune the carrier concentration of the nanocomposites. Due to the Se doping, the thermoelectric figure of merit (ZT) of the nanocomposites is significantly enhanced due to the increased power factor and reduced thermal conductivity. We also find that thermal transport in our hot-pressed pellets is anisotropic, which results in different thermal conductivities along the in-plane and cross-plane directions. Theoretical calculations for both electronic and thermal transport are carried out to establish fundamental understanding of the material system and provide directions for further ZT optimization with adjustments to carrier concentration and mobility.
The strong hydrogen bonding ability of 2-pyridones were exploited to build nanotrains on surfaces. Carborane wheels on axles
difunctionalized with 2-pyridone hydrogen bonding units were synthesized and displayed spontaneous formation of linear nanotrains
by self-assembly on SiO2 or mica surfaces. Imaging using atomic force microscopy confirmed linear formations with lengths up to 5 μm and heights within
the range of the molecular height of the carborance-tipped axles.
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A novel nano- and micro-integrated protein chip (NMIPC) that can detect proteins with ultrahigh sensitivity has been fabricated.
A microfluidic network (μFN) was used to construct the protein chips, which allowed facile patterning of proteins and subsequent
biomolecular recognition. Aqueous phase-synthesized, water-soluble fluorescent CdTe/CdS core-shell quantum dots (aqQDs), having
high quantum yield and high photostability, were used as the signaling probe. Importantly, it was found that aqQDs were compatible
with microfluidic format assays, which afforded highly sensitive protein chips for cancer biomarker assays.
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One-dimensional magnetic Ni-Co alloy microwires with different microstructures and differently shaped building blocks including
spherical particles, multilayer stacked alloy plates, and alloy flowers, have been synthesized by an external magnetic field-assisted
solvothermal reaction of mixtures of cobalt(II) chloride and nickel(II) chloride in 1, 2-propanediol with different NaOH concentrations.
By adjusting the experimental parameters, such as precursor concentration and Ni/Co ratio, Ni-Co alloy chains with uniform
diameters in the range 500 nm to 1.3 μm and lengths ranging from several micrometers to hundreds of micrometers can be obtained.
A mechanism of formation of the one-dimensional assemblies of magnetic Ni-Co microparticles in a weak external magnetic field
is proposed.
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We report a facile approach to synthesize narrow and long graphene nanoribbons (GNRs) by sonochemically cutting chemically
derived graphene sheets (GSs). The yield of GNRs can reach ∼5 wt% of the starting GSs. The resulting GNRs are several micrometers
in length, with ∼75% being single-layer, and ∼40% being narrower than 20 nm in width. A chemical tailoring mechanism involving
oxygen-unzipping of GSs under sonochemical conditions is proposed on the basis of experimental observations and previously
reported theoretical calculations; it is suggested that the formation and distribution of line faults on graphite oxide and
GSs play crucial roles in the formation of GNRs. These results open up the possibilities of the large-scale synthesis and
various technological applications of GNRs.
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Magnetic nanowires (NWs) are ideal materials for the fabrication of various multifunctional nanostructures which can be manipulated
by an external magnetic field. Highly crystalline and textured nanowires of nickel (Ni NWs) and cobalt (Co NWs) with high
aspect ratio (∼330) and high coercivity have been synthesized by electrodeposition using nickel sulphate hexahydrate (NiSO4·6H2O) and cobalt sulphate heptahydrate (CoSO4·7H2O) respectively on nanoporous alumina membranes. They exhibit a preferential growth along 〈110〉. A general mobility assisted
growth mechanism for the formation of Ni and Co NWs is proposed. The role of the hydration layer on the resulting one-dimensional
geometry in the case of potentiostatic electrodeposition is verified. A very high interwire interaction resulting from magnetostatic
dipolar interactions between the nanowires is observed. An unusual low-temperature magnetisation switching for field parallel
to the wire axis is evident from the peculiar high field M(T) curve.
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In this work, homogeneous Ni0.33Co0.67Se hollow nanoprisms were synthesized successfully in virtue of Kirkendall effect. It is the first time for bimetallic Ni-Co compounds Ni0.33Co0.67Se to be used in lithium-ion batteries (LIBs). Impressively, the Ni0.33Co0.67Se hollow nanoprisms show superior specific capacity (1,575 mAh/g at the current density of 100 mA/g) and outstanding rate performance (850 mAh/g at 2,000 mA/g) as anode material for LIBs. This work proves the potential of bimetallic chalcogenide compounds as high performance anode materials for LIBs.
A new kind of photodetector based on a double-walled carbon nanotube (DWCNT) film and a TiO2 nanotube array with hetrodimensional non-ohmic contacts has been fabricated. Due to the dimensionality difference effect,
the DWCNT film/TiO2 nanotube array photodetector exhibits a much higher photocurrent-to-dark current ratio and photoresponse relative to an Au
film/TiO2 nanotube array device, even at small bias voltage. The photocurrent-to-dark current ratio reached four orders of magnitude
and a high photoresponse of 2467 A/W was found upon irradiation at 340 nm. Furthermore, the photosensitive regions could be
extended into the visible range. The photocurrent-to-dark current ratio reached approximately three orders of magnitude upon
irradiation at 532 nm, where the photon energy is much lower than the band gap of TiO2.
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