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The initial stages of metalorganic chemical vapor deposition of InN have been investigated using two different growth procedures: growth of InN over a GaN buffer layer in one continuous run and growth of InN on a pre-deposited GaN template. While the growth conditions and material quality of the GaN underlying layers are nominally the same, characterization by AFM, X-ray diffraction and PL spectroscopy reveals significantly different material properties of InN islands formed using the two procedures and suggests a different path of evolution during the initial stages of growth. In particular, InN islands grown on a pre-deposited GaN template seem to nucleate directly on the GaN template and are 5 times larger in volume and 2 times lower in surface density as compared with InN growth in one continuous run with the GaN underlying layer. Our studies suggest that the Ga incorporation into the InN during the growth on a GaN buffer layer in one continuous run plays a significant role in altering InN growth mechanisms and material properties.

A simple one-step method to fabricate hierarchically porous TiO{sub 2}/Pd composite hollow spheres without any template was developed by using solvothermal treatment. Pd nanoparticles (2-5 nm) were well dispersed in the mesopores of the TiO{sub 2} hollow spheres via in-situ reduction. In our experiment, polyvinylpyrrolidone played an important role in the synthetic process as the reducing agent and the connective material between TiO{sub 2} and Pd nanoparticles. HF species generated from solvothermal reaction leaded to the formation of TiO{sub 2} hollow spheres and Ostwald ripening was another main factor that affected the size and structure of the hollow spheres. The as-prepared TiO{sub 2}/Pd composite hollow spheres exhibited high electrocatalytic activity towards the reduction of H{sub 2}O{sub 2}. The sensitivity was about 226.72 {mu}A mM{sup -1} cm{sup -2} with a detection limit of 3.81 {mu}M at a signal-to-noise ratio of 3. These results made the hierarchically porous TiO{sub 2}/Pd composite a promising platform for fabricating new nonenzymic biosensors. - Graphical Abstract: A new one-step solvothermal method was developed to prepare Pd nanoparticles embedded hierarchically porous TiO{sub 2} hollow spheres. Due to its unique nanostructure, the prepared TiO{sub 2}/Pd modified GC electrode exhibit a high sensitivity (226.72 {mu}A mM{sup -1} cm{sup -2}),more » a relatively low reduction potential (-0.2 V), a fast response time (

Ultra-long single crystal {beta}-Ag{sub 2}Te nanowires with the diameter of about 300 nm were fabricated through a solvothermal route in ethylene glycol (EG) system without any template. The long single crystal wires were curves, with high purity, well-crystallized, and dislocation-free and characterized by using X-ray powder diffraction (XRD), Differential scanning calorimetry (DSC) analysis, X-ray photoelectron spectroscope (XPS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high-resolution transmission microscopy (HRTEM). The detailed topotactic transformation process from particles into single crystal wires was studied. Furthermore, the electrical conductivity and Seebeck coefficient have been systematically studied between 300 and 600 K. - Graphical abstract: Ultra-long single crystal {beta}-Ag{sub 2}Te nanowires with the diameter of about 300 nm were fabricated by the solvothermal route in ethylene glycol (EG) system without any template. The diagram displays the variation of the phases and morphologies of products with different reaction time.

AgIn{sub 5}S{sub 8} powders were successfully synthesized by a microwave hydrothermal method for the first time. This method is a mild and highly efficient route involves no templates, catalysts, or surfactants. Therefore, it is very promising for the low-cost and large-scale industrial production. The samples were characterized by X-ray diffraction, UV-vis spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The photocatalytic activity of AgIn{sub 5}S{sub 8} nanoparticles was investigated through the degradation of methyl orange under visible light irradiation. Compared with TiO{sub 2-x}N{sub x}, AgIn{sub 5}S{sub 8} has exhibited a superior activity under the same condition. A liquid chromatogram-mass spectrometer was used to separate and identify the dye and degradation products generated during the reaction. According to the experiment results, a possible mechanism for the degradation of organic pollutant over AgIn{sub 5}S{sub 8} was proposed. - Graphical abstract: Compared with TiO{sub 2-x}N{sub x}, AgIn{sub 5}S{sub 8} has exhibited a superior activity under the same condition.

Plate-like Bi 5 Nb 3 O 15 (B5N3) particles and rectangular KNb 5 Bi 2 O 16 (KN5B2) particles were synthesized by the molten salt process and topochemical microcrystal conversion (TMC), respectively. The effects of the synthesis parameters on the phase structure and morphology of B5N3 precursor and KN5B2 were investigated. Results indicated that the retro-synthesis process of the as-synthesized KN5B2 retained the morphology and structural feature of the B5N3 precursor. The prepared KN5B2 particles with high aspect ratio of 20–30 are promising templates for texturing bismuth-layer and alkali niobate based ceramics by (reactive) templated grain growth method. The same method can be applied to other perovskite-structured templates.

ZnO nanorod arrays are grown on a-plane GaN template/r-plane sapphire substrates by hydrothermal technique. Aqueous solutions of zinc nitrate hexahydrate and hexamethylenetetramine were employed as growth precursors. Electron microscopy and X-ray diffraction measurements were carried out for morphology, phase and growth orientation analysis. Single crystalline nanorods were found to have off-normal growth and showed well-defined in-plane epitaxial relationship with the GaN template. The 〈0 0 0 1〉 axis of the ZnO nanorods were observed to be parallel to the 〈1 0 1¯ 0〉 of the a-plane GaN layer. Optical property of the as-grown ZnO nanorods was analyzed by room temperature photoluminescence measurements.

The iron nanoparticles confined in highly ordered mesoporous carbons (OMCs) have been directly synthesized through a simple soft templating method by using resorcinol–formaldehyde (RF) as a carbon precursor, triblock copolymer Pluronic F127 as a template agent and hydrated iron nitrite as an iron source. This synthesis was carried out by the carbonization of the F127/[Fe(H 2 O) 9 ](NO 3 ) 3 /RF composites self-assembled in an acidic medium, which was generated from the self-hydrolysis of precursory salt. The effects of iron loading contents on the morphology, pore feature and magnetic properties of the iron nanoparticles confined in OMCs were characterized by the X-ray diffraction, transmission electron microscopy, nitrogen sorption and vibrating-sample magnetometer measurement. It was found that Fe 3+ was captured by the network of F127/RF and further reduced into metallic Fe nanoparticles during the carbonization. The results showed that the carbon material exhibited highly ordered mesoporous structure, and the iron nanoparticles were uniformly confined in the OMC walls when the Fe/R molar ratio was around 0.1. The saturation magnetization Ms , remanent magnetization Mr , and coercivity Hc of the Fe/OMC composites increased with the increasing of Fe/R molar ratio. The Fe/OMC composites exhibited the soft ferromagnetic behavior and the magnetization parameters could be adjusted by the content of iron.

Randomly aligned nerve cells in vitro on conventional culture substrata do not represent the complex neuronal network in vivo and neurites growing in uncontrolled manner may form neuroma. It is of great importance to mimic the organised growth pattern of nerve cells in the study of peripheral nerve repair. The aim of this work was to modify and optimize the photolithographic technique in creating a reusable template in the form of a silicon wafer that could be used to produce contact guidance on biodegradable polymer surface for the orientated growth of nerve cells. Micro-grooves (approximately 3 μm in depth) were etched into the silicon template using KOH at increased temperature. The originality of this work lies in the low cost and high efficiency method in producing microgrooves on the surface of biodegradable ultra-thin polymer substrates (50-100 μm), which can be readily rolled up to form clinically implantable nerve conduits. The design of a pattern with small ridge width (i.e., 5 μm) and bigger groove width (i.e., 20 μm) favored the alignment of cells along the grooves rather than on the ridges of the patterns, which minimized the effect of cross growing of neurites between adjacent grooves. Effectively, enhanced nerve regeneration could be anticipated from these patterned conduits.

An amphiphilic poly(L-lysine·HBr)-block-poly(L-leucine) (KL) diblock copolypeptide and its supramolecular assembly are used as a template to direct silica formation, which proceeds by a cooperative process involving biomimetic mineralization and copolypeptide reassembly under ambient conditions. Various silica structures can be obtained by using different counterions, changing the chain length of the KL diblocks, and applying a sol-gel mineralization method. We find that the chain length of the KL diblock is an important factor in terms of controlling biosilica morphologies. We also find that the nature of the counterions strongly affects the resulting silica structures. For the same KL diblock, variation of anions from phosphate to sulfate and to carbonate can produce hexagonal silica platelets, silica rods, and fused silica platelets, respectively. In contrast, application of a sol-gel method can replicate the copolypeptide fibril network morphology in water, while employment of ultrasonication to the sol-gel medium transforms the silica fibrils to rigid silica rods. The resulting silica morphology has been systematically characterized using SEM and TEM, and the polypeptide conformation is explored using FT-IR and CD spectroscopy.

Hydrothermal synthetic method has been used to prepare complex [ZnL] n ( 1 ) (H 2 L = 4-[(1H-imidazol-4-yl)methylamino]benzoic acid) as spherical microparticles. Slow morphological changes from small spindle-shaped particles to smoother spherical particles in the growth process of complex 1 were observed. Subsequently complex 1 was used as precursor as well as sacrificial template to synthesize hexagonal ZnO nanomaterials by calcination in air. The structure of the final products and the formation process were characterized by measurements of X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The formation mechanism of the final nanorods was proposed on the basis of the structural change of complex 1 in the calcination process. The photocatalytic properties of complex 1 and prepared ZnO have also been studied, and the results showed that all these nano-/micromaterials have photocatalytic properties and ZnO formed under lower calcinated temperature has higher photocatalytic activity.

Article history:Received 30 April 2009Received in revised form 16 June 2010Accepted 6 July 2010Available online xxxxKeywords:Silver nanoparticlesRaman scatteringSurface enhanced raman scatteringMagnetron sputteringAnodic aluminum oxideScanning electron microscopy Low-cost and highly sensitive surface-enhanced Raman scattering (SERS) substrates have been fabricated bya simple anodizing process and a magnetron sputtering deposition. The substrates, which consist of silvernanoparticles embedded on anodic aluminum oxide (AAO) templates, are investigated by a scanningelectron microscope and a confocal Raman spectroscopy. The SERS activities are demonstrated by Ramanscattering from adsorbed solutions of methylene blue and pyridine on the SERS substrate surface. The mostoptimized SERS substrate contains the silver nanoparticles, with a size distribution of 10–30 nm, depositedon the AAO template. From a calculation, the SERS enhancement factor is as high as 8.5×10 7 , which suggestsstrong potentials for direct applications in the chemical detection and analyses.© 2010 Elsevier B.V. All rights reserved.

In this work we report on a method for fabricating highly ordered nanostructures of niobium and hafnium metals by physical vapour deposition using two different templates: anodized aluminum oxide membranes (AAO) and zirconium onto AAO membranes (Zr/AAO). The growth mechanism of these metal nanostructures is clearly different depending on the material used as a template. A different morphology was obtained by using AAO or Zr/AAO templates: when the metal is deposited onto AAO membranes, nanospheres with ordered hexagonal regularity are obtained; however, when the metal is deposited onto a Zr/AAO template, highly ordered nanocones are formed. The experimental approach described in this work is simple and suitable for synthesizing nanospheres or nanoholes of niobium and hafnium metals in a highly ordered structure.

Two couples of new compounds templated by the polyanion [SiW12O40]4−,[Hbix][CuI(bix)]3[SiW12O40]·4H2O (1) and [CuII(H2O)(Hbix)2(bix)]2[CuII(H2O)2(Hbix)2(bix)][SiW12O40]3·4H2O (2) (bix = 1,4-Bis(imidazol-1-ylmethyl)benzene), [CuI(bbi)]4[SiW12O40]·2H2O (3) and [CuII(bbi2)]2[SiW12O40] (4) (bbi = 1,1′-(1,4-butanediyl)bis(imidazole)) were hydrothermally synthesized, and characterized by elemental analyses, IR spectroscopy, thermogravimetric analyses and single X-ray diffraction. Compounds 1 and 2 were synthesized from the same reactants but exhibited distinct structures which could be ascribed to the different ratios of the reactant bix to CuII. In compound 1, the higher ratio of bix results in the transformation of the CuII to CuI, the [SiW12O40]4− templates direct the CuI–bix coordination polymers to form a 3D supramolecular framework with grid-like channels along two directions. The [SiW12O40]4− templates in compound 2 locate in the voids of the 3D supramolecular network constructed by CuII–bix coordination polymers, which exhibits the interdigitation fashion in both the formation of the 2D layer and the 3D framework. Compounds 3 and 4 were synthesized similar to 1 and 2, except for the change of bix to bbi. In compound 3, the CuI–bbi polymers form a supramolecular metal–organic host framework with rhombic channels in which the SiW12 templates reside. Compound 4 shows a framework with hexagonal channels constructed by CuII–bbi coordination polymers which accommodated the SiW12 templates.

Uniform and well-defined single-crystalline Ln(OH)3 and La(OH)3:Eu3+ (Ln: lanthanide ion) nanorods were successfully synthesized by a large-scale and facile hydrothermal method only using Ln(NO3)3·6H2O as lanthanide source and H2O2 as controller without any surfactant or template. The as-formed product via the hydrothermal process, La(OH)3:Eu3+, could transform to hexagonal La2O3:Eu3+ with the same morphology by a postannealing process. The above mentioned samples were characterized by means of X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and photoluminescence (PL) spectra. By tuning the hydrothermal treatment time, a morphological evolution between the nanoparticles and nanorods was observed. Furthermore the growth mechanism and the morphological evolution of different shapes were investigated. Unlike traditional synthesis of Ln(OH)3, H2O2 does not leave any impurity in the reaction system and makes the process very simple to obtain and separate the nanoparticles, nanomultipods and nanorods morphology. The La2O3:Eu3+ nanorods exhibit a strong red emission corresponding to 5D0 → 7F2 transition (625 nm) of Eu3+ under UV light excitation (282 nm), which have potential applications in fluorescent devices.

We report a simple, versatile, two-step fabrication technique for synthesizing a core–shell nanorod array whose architecture is specifically suited for use as an electrode in a dye sensitized solar cell (DSSC). The particular structure fabricated by us consists of a parallel array of 5 μm long and 150–200 nm wide Ag nanorod cores, each coated with a 15–20 nm thick ZnO shell. Importantly, the shell thickness is roughly uniform throughout the length of the rods, which are free standing but distinctly separated from each other. This would allow the dye to penetrate freely and cover the ZnO surface completely in a DSSC.

Nonstoichiometric (Cu 2− x Se) and stoichiometric (CuSe, β-Cu 2 Se and Cu 2 Se) copper selenide hexagonal nanoplates have been synthesized using different general and convenient copper sources, e.g. copper chloride, copper sulphate, copper nitrate, copper acetate, elemental copper with elemental selenium, friendly ethylene glycol and hydrazine hydrate in a defined amount of water at 100 °C within 12 h adopting the solvothermal method. Phase analysis, purity and morphology of the product have been well studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray diffraction (EDAX) techniques. The structural and compositional analysis revealed that the products were of pure phase with corresponding atomic ratios. SEM, TEM and HRTEM analyses revealed that the nanoplates were in the range 200–450 nm and the as-prepared products were uniform and highly crystallized. The nanoplates consisted of {0 0 1} facets of top–bottom surfaces and {1 1 0} facets of the other six side surfaces. This new approach encompasses many advantages over the conventional solvothermal method in terms of product quality (better morphology control with high yield) and reaction conditions (lower temperatures). Copper selenide hexagonal nanoplates obtained by the described method could be potential building blocks to construct functional devices and solar cell. This work may open up a new rationale on designing the solution synthesis of nanostructures for materials possessing similar intrinsic crystal symmetry. On the basis of the carefully controlled experiments mentioned herein, a plausible formation mechanism of the hexagonal nanoplates was suggested and discussed. To the best of our knowledge, this is the first report on nonstoichiometric (Cu 2− x Se) as well as stoichiometric (CuSe, β-Cu 2 Se and Cu 2 Se) copper selenide hexagonal nanoplates with such full control of morphologies and phases by this method under mild conditions.

A simple aqueous solution route was introduced for the fabrication of uniform Eu(OH) 3 and Eu 2 O 3 nanospindles, nanorods and nanobundles by using Eu(NO 3 ) 3 and NaOH as the starting reaction reagents at room temperature and atmosphere pressure without any surfactant and template. The influence of the molar ratios of [OH − ]/[Eu 3+ ], reaction time, and temperature was investigated. It is demonstrated that the size of Eu(OH) 3 nanospindle can be well tuned by adjusting the [Eu 3+ ]/[OH − ] molar ratios. The possible growth mechanism of Eu(OH) 3 and Eu 2 O 3 nanostructures is also discussed. The room-temperature photoluminescence analysis shows that Eu 2 O 3 nanostructures have an intensive emission peak of Eu 3+ ion at around 611 nm due to the 5 D 0 – 7 F 2 forced electric dipole transition of Eu 3+ ions. It is found that the relative peak intensity increases with increasing reaction time.

CoFe2 nanowires with high aspect ratios were electrodeposited into the anodic aluminum oxide (AAO) template. The coercivities and remanence measured along the longitudinal axis of the nanowires are found to increase with the length of nanowires. The magnetostatic interaction between the nanowires is responsible for the decrease of coercivity and remanence of an array of nanowires as compared to an isolated single nanowire. By considering the magnetostatic interaction between the nanowires, a simple model as a function of length is used to calculate the coercivity in an array of the nanowire and this model shows good agreement with experimental data.

Development of multifunctional drug delivery vehicles with therapeutic and imaging capabilities as well as in situ methods of monitoring of intracellular processes will greatly benefit from a simple method of preparation of plasmonic Au structures with nanometer scale gaps between sharp metallic elements where the so-called SERS hot spots can be formed. Here the synthesis of gold lace capsules with average diameters ca. 100 nm made of a network of metallic branches 3-5 nm wide and separated by 1-3 nm gaps is reported. Biocompatible amphiphilic polyurethanes (PUs) were used as template for these particles. The unusual topology of the produced gold lace shells somewhat reminiscent of Fabergé eggs is likely to reflect the network of hydrophobic and hydrophilic domains of PU globules. The gold lace develops from initial open weblike structures by gradual enveloping the PU template. The diameter of gold lace shell is determined by the size of PUs in water and can be adjusted by the molecular mass of PUs. The close proximity between branches makes them excellent supports for surface-enhanced Raman spectroscopy (SERS), which was demonstrated using 1-naphthalenethiol upon excitation with photons with different wavelengths. The loading and releasing of pyrene as a model of hydrophobic drugs and the use of SERS to monitor it were demonstrated.

Supramolecular assembly (SMA) between poly(styrene)-b-poly(4-vinylpyridine) (PS-b-P4VP) and 1-pyrenebutyric acid (PBA) is investigated in thin films after annealing in a 1,4-dioxane atmosphere. The PBA selectively enriches with the P4VP block through hydrogen bonding between the carboxylic group of 1-pyrenebutyric acid and pyridine ring of P4VP. The supramolecular assembly of PS-b-P4VP with 1-pyrenebutyric acid resulted in changing the cylindrical morphology of pure block copolymer into lamellar morphology in thin film due to the increase of the block compositions of P4VP (PBA). Pure block copolymer after solvent annealing shows cylindrical microdomains normal to the substrate with a periodicity ∼26 nm, whereas the SMA complex shows perpendicularly oriented lamella with a periodicity ∼29 nm. These thin films were further immersed in ethanol, a good solvent for P4VP/P4VP (PBA) and a nonsolvent for PS to generate nanotemplates. These nanotemplates are effectively used for the fabrication of arrays of nanowi...

One flexible star-shaped bridging molecule tris-(4-cyanophenyl)amine (TCPA) is synthesized from tris-(4-iodophenyl)amine by treatment with CuCN in hexamethylphosphorotriamide (HMPA) as a catalyst in high yield. Anion-template-controlled reactions of TCPA and silver salts give a series of coordination polymers (CPs) with various topological patterns. The complex [Ag(TCPA)(ClO4)]n·nC6H6 (1) forms an undulating 4.82 network, which displays unusual net entanglement. Two 4.82 nets interweave each other to give rise to 2-fold interpenetrating basic layers, which link together via double μ-Operchlorate bridging interactions. The complex [Ag(TCPA)(CF3SO3)]n·2nC6H6 (2) forms noninterpenetrating (6,3) nets. The solid state structure of [Ag3(TCPA)(CF3CO2)3]n·nCH2Cl2 (3) also is a (6,3) honeycomb network, differently, including a sphere-type Ag4(CF3CO2)62− cluster-anion in the host frameworks, which is a rare example of the host cationic network containing a guest cluster-anion. The complexes [Ag(TCPA)(BF4)·0.5H2O]n·...

FeNi nanowires were fabricated by ac and pulse electrodeposition into the alumina template matrix. The effects of continuous ac electrodeposition as well as pulse features on the structure and magnetic properties of the nanowire arrays were studied. The microstructures and magnetic properties of the FexNi1−x nanowires are seen to be independent of the deposition frequency and off-time between the pulses. The ac electrodeposited Ni nanowires were not formed at more than 400 Hz deposition frequency, while the FexNi1−x nanowires, containing a small amount of Fe, formed in the all frequencies. For x less than 50% the coercivity slowly increases but over 50% Fe added to the FeNi alloy increases the coercivity with a higher rate and maximum coercivity was seen for the Fe0.97Ni0.03. The Fe and FexNi1−x nanowires containing less than 30 at.% Ni was seen to have a bcc structures with (110) preferential direction while FexNi1−x nanowires with more than 30 at.% Ni showed (110) bcc (Fe) and/or (111) bcc (FeNi) plus (111) fcc (Ni). A preferential (111) fcc structure was obtained for the Ni nanowires.

High yield syntheses of size-confined Bi2Te3 and Sb2Te3 nanocrystals and nanoflakes, and their alloys, were carried out by a facile glycol-mediated solvothermal process. Phase purity and good cryst...

A monoclinic tungsten trioxide (WO3) nanosphere film was synthesized via a sal gel approach using an amphiphilic diblock copolymer polystyrene-b-polyacrylic acid (PS-b-PAA) as template in toluene. The morphology, surface area and crystal structure of as-synthesized WO3 were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET (N-2) and powder X-ray diffraction (XRD). The XRD pattern of WO3 nanosphere film can be identified as a pure monoclinic WO3 phase. The WO3 precursor nanospheres had diameters ranging from 20 to 150 nm and surface area of 78.8 m(2) g(-1). The hydrogen gasochromic experiments revealed that such WO3 nanosphere film with high surface area had a rapid response (5 similar to 10 s) to pure hydrogen at room temperature. (C) 2010 Elsevier Masson SAS. All rights reserved.

Using polystyrene (PS) opal templates and RF magnetron sputtering, three-dimensional (3D) zinc oxide (ZnO) photonic crystals (PCs) of core–shell structures are prepared. Scanning electron microscopic (SEM) spectra show that there are up to five layers in the samples while X-ray diffraction (XRD) spectra indicate that they are of hexagonal wurtzite structures, preferentially (0 0 2) oriented. Ultraviolet–visible (UV–vis) spectra confirm the existence of photonic band gaps (PBG) in the samples.

In this paper, we report the successful synthesis of mesoporous MnO2 nanospheres composed of nanosheets via a facile hydrothermal route without any template. The phase and morphology of the products were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The reaction time played an important role in the formation of mesoporous MnO2 nanospheres. The obtained nanospheres showed superior catalytic ability in the degradation reaction of an aqueous solution of Rhodamine B (RhB) in the presence of H2O2. Electrochemical measurements predicted that the mesoporous MnO2 nanosphere-modified electrode showed good electrocatalytic properties for the reduction of H2O2 in alkaline medium, which might have wide application in electrochemical analysis.

AB diblock copolymers of poly(2-(dimethylamino)ethyl metharylate-block-potassiurn acrylate) were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. The structure of the block polymer was determined by the nuclear magnetic resonance (NMR) spectroscopy and the gel permeation chromatography. Moreover, it has also been shown that the diblock copolymers exhibit aggregate as function of the pH according to the result of 1H-NMR spectroscopy, FT-IR absorption spectra, UV-vis transmittance spectroscopy, transmission electron microscopy and ultrasonic particle size analyzer. The result was attributed that such AB diblock copolymers were tailored to undergo pH-induced self-assembly. Furthermore, the aggregate can be as template of metal nanoparticles preparation, and the sizes of the aggregate, in turn, strongly control nanoparticle sizes.

We present a facile one-step approach to large-scale production of single-crystal magnetite Fe3O4 nanosheets (NSs) employing a solid-state thermal decomposition route without the assistance of any template, carrier gas, and other additions. Single-crystal Fe3O4 NSs with average edge length in the range of 80–100 nm and thickness of about 30 nm were synthesized on a large scale via direct pyrolysis of inorganic–organic hybrid EDTA ferric sodium salt in a one-end closed and horizontal quartz tube furnace in the air. A series of techniques, including XRD, IR, TEM, HRTEM, and TGA, were used to characterize the final products. The HRTEM image obtained from a typical individual nanosheet displays a highly symmetrical lattice, which reveals the single-crystalline nature of the obtained Fe3O4 NSs. Furthermore, a possible formation mechanism from EDTA ferric sodium salt to Fe3O4 was also discussed. All the obtained Fe3O4 NSs are ferromagnetic at room temperature. This method is simple and facile and could synthesize other metal oxides under such experimental conditions.

Nearly monodisperse BaTiO3 hollow nanoparticles were prepared through a one-pot template-free route in molten hydrated salt medium. The composition and morphologies of the time-dependent products were investigated in detail, and Ostwald ripening is concluded to be responsible for the hollowing evolvement of the BaTiO3 particles. The size of the initial solid particles is proposed to play an important role in determining the evacuation manner of the solid in the ripening-induced hollowing process, that is, evacuating from the center region or underneath the surface layer of the solid aggregates, and could result in the morphology variation (i.e., hollow geometry or core−shell one) of the final products. Our study also points out that a highly active precursor is crucial to improve the uniformity of the products, and elevated reaction temperature is a prerequisite to activate the hollowing evolvement of solid aggregates. Second-harmonic-generation and Raman analyses revealed the ferroelectric tetragonal cha...

Ag···Ag interactions were shown to template [2 + 2] photochemical reactions of unsymmetrically substituted olefin molecules, namely 4-pyridyl acrylic acid (1), 4-pyridyl acryl amide (2), and methyl ester of 4-pyridyl acrylic acid (3) in their Ag(I) complexes [Ag(1)2(NO3)]·MeOH (4); [Ag(2)2(NO3)] (5); and [Ag(3)2(NO3)]·MeOH (6). Nitrate ions were found to bridge these Ag···Ag interactions in two ways: as a discrete dimer in 4 and 5 and as a zigzag 1D-polymer in the case of 6. Irradiation of these complexes in UV/sunlight produced respective head-to-head dimers in nearly 100% yields, as supported by 1H NMR spectroscopy. In the case of 5, the transformation was shown to occur in single crystal to single crystal fashion by determining the crystal structure of partially irradiated materials of 5. Further, we have also found that the irradiation of mechanically grounded samples of AgNO3 with 2 or 3 produces a similar [2 + 2] reaction, to result in respective head-to-head dimers in good yields.

The strategy to manipulate nanoscale building blocks into well-organized hierarchical architectures is very important to both material synthesis and nanodevice applications. In this work, hierarchical ZnO nanostructures with controllable morphology were synthesized by a two-step chemical route. At step-one, hexagonal- and spherical-shaped ZnO nanostructures were deposited on glass slide substrates. At step two, the morphology of hierarchical ZnO nanostructures could be effectively controlled by changing the composition of solutions. The method described here is a simple and reproducible process, which does not require any templates, catalysts, or surfactants, but can control the morphology of ZnO crystals from simple to complex. The morphologies and structures of the products were characterized by field-emission scanning electron microscopy and X-ray diffraction measurements. Room-temperature photoluminescence spectra demonstrate that the variety of nanostructures can cause the variation of the photoluminescence intensity, suggesting that the controlled morphologies can be used to modulate the optical properties of ZnO nanostructures.

MoO 2 microspheres were synthesized by a facile wet chemical method using the molybdenum trioxide as an inorganic precursor and paraphenylendiamine as a reducing agent and also a template, via a hydrothermal way. The as prepared product was characterized by XRD, SEM, TEM, DTA–TG, and IR. It was found that this product was composed by MoO 2 nanoparticles encapsulated into the organic shell microspheres with diameters of 1–3 μm. The influence of the temperature on the crystallinity of the products was investigated. Optimal conditions founded were: reaction temperature: 220 °C, reaction time: 72 h and cooling time remains unchanged. The possible formation mechanism of MoO 2 microspheres was also discussed.

In order to obtain oriented nano/micro-structured materials via a simple method for potential nanoelectronic/microelectronic applications, a study on preparation of oriented ZnO structures under hydrothermal reaction condition was carried out. The deposition film was characterized with scanning electron micrographs (SEM), X-ray diffraction (XRD) and photoluminescence (PL) spectra. The experimental results under the optimized reaction condition indicated that a ZnO nanotube array on a glass substrate can be directly formed via a one-step approach in ammonia aqueous solution. The XRD results showed the highly preferential growth of the ZnO nanotubes along the c -axis orientiation. The PL results showed the strong photoluminescence property of the ZnO nanotube array in a wide light range (387–416 nm). The possible mechanism to form the ZnO nanotube array via such a simple in-situ deposition approach was discussed. This template-less, surfactant-free and seed-free aqueous synthesis method makes it possible to synthesize large-scale, low-cost and well-oriented ZnO nano/microtube film at moderate temperature.

The hydro(solvo)thermal self-assembles of CuI, KI and 2,5-dicarboxylpyridine [2,5-(COOH){sub 2}py] in different molar ratios in H{sub 2}O/alcohol solutions produced three Cu coordination polymers as 2-D [N-C{sub 2}H{sub 5}py][Cu{sub 3}I{sub 4}] 1, 1-D [N-CH{sub 3}py][Cu{sub 2}I{sub 3}] 2 as well as 1-D [Cu(2-COOpy){sub 2}]{center_dot}H{sub 2}O 3 (N-C{sub 2}H{sub 5}py=N-ethylpyridine, N-CH{sub 3}py=N-methylpyridine, 2-COOpy=2-carboxylpyridine). N-C{sub 2}H{sub 5}py in 1 and N-CH{sub 3}py in 2 derived from the solvothermal in situ simultaneous decarboxylation and N-alkylation reactions of 2,5-(COOH){sub 2}py. The semi-decarboxylation reaction of 2,5-(COOH){sub 2}py into 2-COOpy occurred in the preparation of 3. X-ray single-crystal analysis revealed that CuI is transformed into a 2-D [Cu{sub 3}I{sub 4}]{sup -} layer in compound 1 and a 1-D chain in compound 2, templated by [N-C{sub 2}H{sub 5}py]{sup +} and [N-CH{sub 3}py]{sup +}, respectively. Compound 3 is a divalent Cu compound. The Cu(II) centers with a 4+2 geometry are coordinated by {mu}{sub 3}-mode 2-COOpy ligands. All of the title compounds were characterized by CHN analysis, IR spectrum analysis and TG analysis. Compounds 1 and 2 exhibit fluorescence properties with the maximum emissions at 581 nm for 1 and 537 nm for 2. - Graphical abstract: Three compounds were obtained via in situ metal-ligand hydro(solvo)thermal reactions of 2,5-(cooh){sub 2}pymore » with cui. Three types of in situ reactions occurred for 2,5-(cooh){sub 2}py: decarboxylation n-ethylated in 1, n-methylated in 2 and semi-decarboxylation in 3.« less

We reported a simple, large-scale, and controllable growth method for network-like branched single-crystalline Si 3 N 4 nanostructures by catalyst-assisted pyrolysis of a polysilazane. The templates were a silicon wafer deposited with a 5 nm Fe film. The processes simply involved in thermal cross-linking of the polymer precursor, crushing of the solidified preceramic polymer chunks into fine powder, and thermal pyrolysis of the powder under the protection of ultra-high purity nitrogen. The collected white network-like branched nanostructures were formed through “metal-absorption on the surface of nanostructures” model by vapor-liquid-solid mechanism. Microstructure characterizations indicate that the nanostructures are single-crystalline hexagonal α-Si 3 N 4 . The reaction mechanism of Si 3 N 4 nanonetworks was also proposed.

One to 2-µm long, ≤ 400-nm wide amorphous tris(8-hydroxyquinoline)aluminum (III) (Alq3) nanowires (NWs) grown from the 15-min boiled outer shell membrane (OSM) of the hen's egg and from the OSM solution cast film via thermal evaporation with a source temperature of 260 °C and a substrate temperature of 138 °C under 6.7 × 10 − 2 Pa gave about 1.4 to 1.7 times more photoluminescence emission than the control Alq3 sample did, which was grown from the plain glass surface. The characteristic bonding energies of C 1s X-ray photoelectron signal at 282 eV, O 1s signal at 529 eV and N 1s signal at 397 eV suggested that the relatively high NW density for the 15-min boiled OSM and the OSM solution cast film, was mainly caused by the formation of the O═C–O–C═O anhydride moiety and the C═N group in the proteinaceous OSM at high temperature of 90 °C to 100 °C. Therefore, we proposed that the 15-min boiled OSM and the OSM solution cast film apparently served as good templates by providing nano-regions of high concentration of the O═C–O–C═O anhydride groups and the C═N groups for nesting the Alq3 gas molecules to form nano-conical Alq3 nuclei for the growth of long and narrow NWs.

CuO hierarchical hollow nanostructures, assembled by nanosheets, were successfully prepared in n-octanol/aqueous liquid system through a microwave approach. Controlled experiments revealed that both bubble and interface play key roles in determining the self-assembly process of CuO hierarchical hollow nanostructures, and the morphology/size of building blocks and final products could be readily tuned by adjusting reaction parameters. Furthermore, a self-assembly mechanism of aggregation-then-growth process through bubble template was proposed for the formation of the hollow hierarchical architectures. Photocatalytic performance evidenced that the obtained CuO hierarchical hollow nanostructures possessed superior photocatalytic efficiency on RhB than that of non-hollow nanostructures, which could be easily demonstrated by SPS response about the separation and recombination situation of photogenerated charges.

Zeolite Beta Aggregates have been synthesized by the self-assembly of Beta nanoparticles without the use of second template or additive, where the large zeolitic aggregates avoided the filtration difficulties and the presence of mesopore reduced the diffusion limitation. The samples were characterized by XRD, N2-sorption, SEM, TEM, thermogravimetric analysis, IR spectroscopy and temperature programmed desorption of ammonia. The results showed that the SiO2/Al2O3 ratio played a key role on the particle size, mesopore volume and particle–particle aggregation process of zeolite Beta. The sample with SiO2/Al2O3 ratio below 60 had improved textual and acidic properties and exhibited the best catalytic activity to the alkylation of phenol with tert-butanol.

Todorokite-type manganese oxide octahedral molecular sieves (OMS-1) have been extensively studied due to their potential applications as materials. In this study, a nanofibrous todorokite-type, tun...

This study represents a key evolution in the synthesis of the superconductor MgB2, as it is the first to demonstrate that templated synthesis can be carried out successfully without a sealed reaction vessel. This is possible owing to the strong chelating ability of the biopolymer dextran, whose morphological complexity effectively cocoons the reaction, preventing oxygen ingress. This synthetic protocol demonstrates that not only can this important material be synthesized as nanoparticles but that, as the morphological template is calcined, it effectively carbon-dopes the superconducting phase, thereby improving the critical current density by a factor of five.

A new three-dimensional Mo/O/MnII/tetrazole compound [Mn(ptz)Mo2O7] (1) (ptz = 5-(2-pyridyl)tetrazole) was synthesized by a hydrothermal method. It represents the first example of a molybdenum-oxid...

Polycrystalline CdS hollow nanospheres with diameter of about 130 nm have been successfully synthesized in high yield by an ionic liquid (IL) assisted template-free hydrothermal method for the first time. Both the molar ratios of Cd/S precursor in the solution and the reaction temperature play important roles in the formation of the CdS hollow nanospheres. The concentrations of capping agent hexamethylenetetramine (HMT) and polyvinylpyrrolidone (PVP) are also crucial for the morphology and size of the final product. IL was found to be a key component in the formation of CdS hollow structures, because solid spheres were obtained in the absence of IL. A subsequent growth mechanism of hollow interior by localized Ostwald ripening process has been further discussed. Such hollow structures show high photocatalytic ability in the photodegradation of methylene blue.

We successfully fabricated a square pattern of anodic alumina oxide (AAO) template in thin Al film grown on Si substrate utilizing focused ion beam (FIB) milled indent. The pore size and its period of the square matrix were about 50 nm and 100 nm, respectively. We found that the minimum indented depth is required to satisfy the critical electric field which is a vertical component toward downward. In addition, we found that the anodizing voltage plays an important role in determining the pore shape and uniformity. The higher anodizing voltage not only reduces the minimum indent depth that is required to create a matrix array but also improves the uniformity of pore shapes in the matrix array.

Three-dimensionally ordered macroporous (3DOM) lanthanum–iron-oxide (LaFeO3) with different pore diameters was prepared using a colloidal crystal of polymer spheres with different diameters as templates. Ethylene glycol–methanol mixed solution of metal nitrates was infiltrated into the void of the colloidal crystal template of a monodispersed poly(methyl methacrylate) (PMMA) sphere. Heating of this PMMA–metal salt–ethylene glycol composite produced the desired well-ordered 3DOM LaFeO3 with a high pore fraction, which was confirmed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), mercury (Hg) porosimetry, and ultraviolet–visible (UV–vis) diffuse reflectance spectra. 3DOM LaFeO3 with pore diameters of 281 and 321 nm shows opalescent colors because of photonic stop band properties. Catalytic activity of the 3DOM LaFeO3 for combustion of carbon particles was enhanced by a potassium cation, which was involved from K2S2O8 used as a polymerization initiator.

Homoepitaxial MgZnO thin films were grown from PLD targets with 1, 2, 4, and 10 wt.% MgO content on ZnO-buffered ZnO(001) substrates. The resulting Mg content of the films was determined from the blue-shift of the excitonic peak in low-temperature photoluminescence spectra. With increasing Mg content a considerable increase of film mosaicity was observed from HR-XRD (002) rocking curves. Triple-axis reciprocal space maps of symmetric (002) and asymmetric (104) reflections show the structural development in terms of tilt and perpendicular and parallel strain. For more than 1% Mg the films exhibit increasing tensile out-of-plane strain. Very high electron mobilities of 200 cm²/Vs at 300 K and 900 cm²/Vs at 65 K were measured in the homoepitaxial MgZnO/ZnO thin films with free electron concentrations around 10 18 and 10 17 cm − 3 , respectively. The homoepitaxial ZnO template film deposited from a melt-grown ZnO single crystal as PLD target shows two orders of magnitude lower carrier concentration due to high compensation.

A facile no-template approach for fabricating curved polystyrene (PS) nanosheets by miniemulsion polymerization technique was developed. Two essences of the high hydrophobicity of oil phase and the existence of cross-linking comonomer were found to ensure the stable curved sheet-like morphology. Here, when choosing tetradecane as the hydrophobic oil phase and divinylbenzene as cross-linker, the curved PS nanosheets with stable structure were obtained. Furthermore, after introducing functional groups by sulfonation reaction, these curved PS nanosheets can be used as a general template for preparing curved sheet-like inorganic/organic nanocomposites with broadly varied inorganic ingredients, such as metal Ag nanoparticles, inorganic titania, silica, etc. Otherwise, when calcining or carbonizing these inorganic/organic nanocomposites under air or nitrogen, novel mesoporous or microporous pure inorganic nanomaterials with curved sheet-like morphology were obtained conveniently further.

In the present work we report on the monocrystalline growth of (00.1) ZnO films on GaN template by the Atomic Layer Deposition technique. The ZnO films were obtained at temperature of 300 °C using dietylzinc (DEZn) as a zinc precursor and deionized water as an oxygen precursor. High resolution X-ray diffraction analysis proves that ZnO layers are monocrystalline with rocking curve FWHM of the 00.2 peak equals to 0.07°. Low temperature photoluminescence shows a sharp and bright excitonic line with FWHM of 13 meV.

Using composite surfactant templates, polyoxyethylene (20) oleyl ether (Brij98) and cetyl trimethyl ammonium bromide (CTAB), as structure-directing agents, N and La co-doped mesoporous TiO{sub 2} complex photocatalysts were synthesized successfully. The micromorphology of co-doped mesoporous TiO{sub 2} samples was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FT-IR), energy-dispersive X-ray spectrometer (EDS) and N{sub 2} adsorption-desorption measurements. The results indicated that the complex photocatalyst prepared with a molar ratio of Brij98:CTAB=1:1 showed a uniform pore size of ca. 7 nm and a high specific surface area (S{sub BET}) of 279.0 m{sup 2} g{sup -1}, and exhibited the highest photocatalytic activity for degradation of papermaking wastewater under ultra-violet light irradiation. The chemical oxygen demand (CODc{sub r}) percent degradation was about 73% in 12 h and chroma percent degradation was 100% in 8 h. - Graphical abstract: CODc{sub r} percent degradation of papermaking wastewater is about 73% after 12 h over the co-doped mesoporous TiO{sub 2} prepared with a molar ratio of Brij98:CTAB=1:1.

The precursors for boehmite and γ-Al2O3, aluminum acetate hydroxide [(CH3COO)2Al(OH)] with various morphologies including nanoleave, nanofibers, and hierarchically nanostructured microflowers, have been successfully synthesized by an ionic liquid-assisted hydrothermal synthetic method using 1-butyl-2, 3-dimethyl imidazollium chloride ([bdmim][Cl]) as a template. The effects of the ionic liquid [bdmim][Cl] on the morphology of the precursors aluminum acetate hydroxide have been investigated systematically. The boehmite and γ-Al2O3 nanostructures were obtained by calcining the as-synthesized precursors at 300 and 600 °C for 2 h, respectively, preserving the same morphology. The proposed formation mechanism of the precursors has also been investigated. The obtained products were characterized by several techniques, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N...

Co thin films with novel hierarchical structures were controllably fabricated by simple electrochemical deposition in the absence of hard and soft templates, which were used as sacrificial templates to further prepare noble metal (Pd, Pt, Au) hierarchical micro/nanostructures via metal exchange reactions. SEM characterization demonstrated that the resulting noble metal thin films displayed hierarchical architectures. The as-prepared noble metal thin films could be directly used as the anode catalysts for the electro-oxidation of formic acid. Moreover, bimetallic catalysts (Pt/Au, Au/Pt) fabricated based on the monometallic Au, Pt micro/nanostructures exhibited the higher catalytic activity compared to the previous monometallic catalysts.