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In this study, a novel anionic template polymer (TPAS) with microblock structure was prepared by ultraviolet light (UV)–assisted template copolymerization (UV-TP). Acrylamide (AM) and sodium styrene sulfonate (SSS) were selected as monomers and polypropylene ammonium chloride (PAAC) was chosen as the template. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), nuclear magnetic resonance hydrogen spectroscopy (1H NMR), and thermogravimetry/differential scanning calorimetry (TG/DSC) were used to characterize the polymer chemical structure. The results showed that the attractive anionic microblock structure was formed in TPAS. Besides, the association constant (KM) and template reaction kinetics analysis results indicated that the polymerization reaction followed I (ZIP) template copolymerization mechanism. It proved the microblock structure formation again. The anionic microblock structure in TPAM could greatly improve the ability of charge neutralization, electrical patching, and bridging. After the hematite wastewater was conditioned by TPAS with this novel anionic microblock structure, the generated hematite flocs had larger particle size and denser structure. It was favorable for the reduction of turbidity, and the turbidity removal rate could reach 97.8%. TPAS showed excellent flocculation performance for hematite wastewater and had a broad market application prospect.

As one of the core technologies employed in the field of sludge conditioning, flocculation has the ability to improve the sludge dewatering performance and reduce its volume and amount, which can accordingly result in lower costs in sludge transportation as well as subsequent disposal. Therefore, the development of new and high-efficiency flocculants is a hot topic in this field. The template copolymer (TPAD) of acryloyloxyethyl trimethyl ammonium chloride (DAC) and acrylamide (AM) was successfully synthesized through ultrasonic-template copolymerization using sodium-polyacrylate (NaPAA) as a template. The analysis of FTIR, 1H (13C) NMR, TG/DSC and SEM revealed that TPAD had a conspicuously significant cationic segmental structure. In addition, the results obtained from the analysis on the association constant (KM) and the kinetics of the template reaction indicated that the ultrasonic-template was a free radical initiated polymerization and the polymerization mechanism was I Zip-up (ZIP), and which once again confirmed the formation of the cationic fragment structure. This novel cationic fragment structure in TPAD greatly enhanced the ability of charge neutralization, electric patching, adsorption and bridging, thus improving the active sludge conditioning and dewatering performance (FCMC: 72.9%, SRF: 4.0 × 1012 m·kg−1, d50: 228.604 μm, Df: 2.02 at 400 r/min). The floc breakage and regeneration experiments showed that the cationic fragment structure in TPAD could make great contribution to the formation of large and dense floc structures, and these flocs were able to regenerate rapidly after breakage. Finally, it was also known that these large and compact floc structures were beneficial to the creation of more channels and voids, thereby decreasing sludge resistance (SRF) and improving sludge dewatering performance.

In this work, one-dimensional Ni-rich LiNi0.6Co0.2Mn0.2O2 microrod cathode material for lithium-ion battery has been firstly prepared by a simple stepwise oxalate co-precipitation method. Rod-like CoC2O4·2H2O formed in the first process is served as template for the formation of MC2O4·2H2O (M=Ni, Co, Mn) precursor, and the morphology of rod-like is maintained after the heat treatment with Li2CO3. The crystalline structure and morphology of the samples are characterized by XRD, SEM, and TEM/HRTEM. The electrochemical performances are evaluated by galvanostatic charge/discharge tests. With the beneficiation of micro/nanostructure, the LiNi0.6Co0.2Mn0.2O2 microrod cathode material shows an initial discharge capacity of 162, 134, 117, and 105 mAh g−1 at 0.1 °C, 1 °C, 3 °C, and 5 °C, respectively, and maintains 72.8% of its initial discharge capacity after 100 cycles at 1 °C.

Ultra-low PtCu loading on carbon nanotubes (CNT) catalysts were synthesized by a novel galvanic displacement (GD) method under sonication conditions. The influence of the type of copper template, reaction time, and Pt concentration in the galvanic displacement bath and their correlation to electrocatalytic activity of the catalysts for oxygen reduction reaction in acidic media were studied. Among the catalysts synthesized, the best catalyst identified through electrochemical analysis was used to prepare Membrane Electrode Assembly and evaluated in a hydrogen fuel cell. The maximum power density of the PtCu/CNT and commercial catalyst (20% Pt/C) in the fuel cell were 452 mW cm−2 at 0.424 V and 358 mW cm−2 at 0.475 V, respectively, clearly showing the superior electrocatalytic capability of the PtCu/CNT catalyst synthesized in this study when compared with the commercial catalyst.

In the family of high-performance cathode materials for lithium-ion batteries, lithium-rich layered oxides come out in front because of a high reversible capacity exceeding 250 mAh g–1. However, the long-term energy retention and high energy densities for lithium-rich layered oxide cathode materials require a stable structure with large surface areas. Here we propose a “bubble template” reaction to build “honeycomb-like” hollow microsphere architecture for a Li1.2Mn0.52Ni0.2Co0.08O2 cathode material. Our material is designed with ca. 8-μm-sized secondary particles with hollow and highly exposed porous structures that promise a large flexible volume to achieve superior structure stability and high rate capability. Our preliminary electrochemical experiments show a high capacity of 287 mAh g–1 at 0.1 C and a capacity retention of 96% after 100 cycles at 1.0 C. Furthermore, the rate capability is superior without any other modifications, reaching 197 mAh g–1 at 3.0 C with a capacity retention of 94% after 10...

A novel in situ templates etching method is used to prepare three-dimensional (3D) interconnected Fe-N doped hierarchical porous carbon materials. Citric acid serves as a carbon source and etchant. Fe2O3 nanoparticles not only provide the iron source by in situ etching but also act as templates to construct the hierarchical porous structure. The prepared optimal sample displays a high specific surface area of 1643.6 m2 g−1 with an interconnected abundant hierarchical porous structure and homogeneous distribution of Fe and N elements in the carbon. The optimized sample displays excellent catalytic oxygen reduction reaction (ORR) performance with a positive half-wave potential (0.85 V), efficient four-electron reaction and excellent durability, which are superior to those of Pt/C (20 wt%) catalyst. Meanwhile, due to the unique interconnected hierarchical porous structure, it also exhibits a high specific capacitance of 378.6 F g−1 at 0.5 A g−1 and an excellent rate capability of 276.6 F g−1 at 20 A g−1 as supercapacitors electrode materials in 6 M KOH. This work provides a simple design for the preparation of 3 D interconnected Fe-N doped hierarchical porous carbon electrode materials that display potential applications in ORR catalysts and supercapacitors.

One-dimension ZnSe and ZnO nanostructures with controlled diameters from 10 to 80 nm and lengths from 30 nm to micrometers were grown via the vapor–liquid–solid growth process using Au nanoparticles as catalysts fabricated by anodic aluminum oxide template assisted vapor deposition. The dependence of the growth on Au nanoparticle (NP) diameters and vapor stoichiometry during growth was investigated. Statistical analysis of the dimensions of nanostructures showed that large Au NPs led to thick and long nanorods (NRs) or nanowires (NWs) within the initial growth phase, but resulted in a slow growth rate as the NRs elongate. The diameter ratio of NRs to Au NPs, or R (Dnanorod/DAu), decreases from 0.45 to 0.32 as the mean length of NRs increases from 30 nm to 230 nm. The composition changes as the NRs elongate, as identified by energy dispersive X-ray analysis, indicate that the stoichiometry of ZnSe NWs can be controlled from Zn-rich to Se-rich; however, for ZnO NRs and NWs, their stoichiometry maintains Zn-rich throughout the growth process. These results are significant for the controlled fabrication of one-dimension nanostructures since their optoelectronic properties are directly determined by their dimensions and composition stoichiometry.

The co-condensation in situ of tetraethoxysilane (TEOS) and mercaptopropyltrimethoxysilane (MPTMS) using cetyltrimethylammonium bromide (CTAB) as a template results in the synthesis of multilayered mesoporous structured SiO2 colloids with “onion-like” chemical environments. Thiol groups were anchored to an inner selected SiO2 porous layer in a bilayered core shell particle producing different chemical regions inside the colloidal layered structure. X-Ray Photoelectron Spectroscopy (XPS) shows a preferential anchoring of the –SH groups in the double layer shell system, while porosimetry and simple chemical modifications confirm that pores are accessible. We can envision the synthesis of interesting colloidal objects with defined chemical environments with highly controlled properties.

Single crystalline tri-wing tellurium nanoribbons with well-defined outer surfaces and geometrical shapes are synthesized by a facile hydrothermal method in the presence of poly(vinyl alcohol) as the surfactant. The tri-wing Te nanoribbons with a length of tens of micrometres have a very thin wing structure with an average thickness about 20 nm. A two-step growth mechanism is proposed for the formation of tri-wing Te nanoribbons based on time dependent morphology evolution. By adjusting the pH value of the reaction solution, varied Te nanostructures including nanofeathers, nanobelts, tri-wing nanoribbons and nanorods are obtained, indicating that the reduction rate plays a key role in fabricating tri-wing Te nanoribbons since the pH value has a dramatic influence on the reduction reaction rate of TeO32−. With tri-wing Te nanoribbons as the precursor and template, Ag2Te nanoribbons in the same shape and similar size are synthesized through the direct reaction of Te with AgNO3 at room temperature, demonstrating that the Te nanoribbons with a very thin tri-wing structure are ideal templates to synthesize other Te related nanocompounds.

Nanopowders of Zr0.95Ce0.05O2 composition have been prepared by a standard Pechini-type sol–gel process and by means of a colloidal crystal template approach. In the latter method, inverse opal Zr0.95Ce0.05O2 powders were fabricated employing poly(methyl methacrylate) (PMMA) colloidal crystals as a template. The effects of the two different synthesis routes on the structure and microstructural characteristics of the prepared nanopowders were evaluated by X-ray diffraction and scanning electron microscopy. For both preparation routes, the X-ray diffraction analysis has shown that a tetragonal fluorite structure is formed with a crystallite size of ∼35–40 nm. The scanning electron microscopy measurements indicate that the powder obtained by the sol–gel Pechini-type process is comprised of nanoparticles that are arranged in agglomerates with shape and size relatively uniform whereas the inverse opal Zr0.95Ce0.05O2 nanopowders exhibit the formation of macropores with a mean size of ∼100 nm. The cathodoluminescence spectra of the prepared Zr0.95Ce0.05O2 nanomaterials have been measured in the 300–800 nm wavelength range. The powder prepared by sol–gel method yields a broad emission band centered at 482 nm whereas the emission from the inverse opal preparation is considerably less intense.

Zeolite beta (Si/Al∼18) was synthesized from a single template reaction mixture in a one-step hydrothermal treatment. By adjusting the synthesis conditions, the formation of isolated nanocrystals or mesoporous aggregates of zeolite beta was achieved. Depending on the synthesis conditions, zeolite beta nanocrystals of approximately 20–150 nm in diameter or mesoporous aggregates of approximately 120–140 nm in diameter were prepared. The use of concentrated synthesis gels resulted in mesoporous aggregates of nanocrystals and diluted reaction mixtures resulted in isolated zeolite nanoparticles. The crystallinity of the samples determined from pXRD patterns is similar to that of commercially available micron-sized zeolite beta. The samples had surface areas of greater than 600 m2/g and mesopore volumes of 0.4–0.5 cc/g.

Square-symmetry patterns are of interest in nanolithography but are not easily obtained from self-assembly of a diblock copolymer. Instead, we demonstrate highly ordered 44 nm period square patterns formed in a thin film of polyisoprene-block-polystyrene-block-polyferrocenylsilane (PI-b-PS-b-PFS) triblock terpolymer blended with 15% PS homopolymer by controlling the film thickness, solvent anneal conditions, the surface chemistry and topography of the substrates. The square patterns consist of PFS pillars that remained after removal of the PI and PS with an oxygen plasma. On an unpatterned smooth substrate, the average grain size of the square pattern was increased dramatically to several micrometers by the use of brush layers and specific solvent anneal conditions. Templated self-assembly of well-ordered square patterns was demonstrated on substrates containing nanoscale topographical sidewalls and posts, written by electron beam lithography, in which the sidewalls and base of the substrate were independently chemically functionalized.

The nucleation of curved graphitic structures such as carbon and boron nitride nanotubes in the absence of catalyst particles is still poorly understood. The nucleation and growth mechanisms of graphitic cones have been even more elusive. We investigate the formation of helical conical fibers of boron nitride (BN) and carbon (C) produced in a catalyst-free environment from the solid-state annealing of an amorphous B–C–N compound. Helical conical fibers consist of a single graphene sheet wrapped conically around an axis. We show that the cones grow radially in clusters, with each cluster arising from a common seed. The radial morphology originates from spherulite-like helicoidal polyhedral particles of BN that serve as templates for the BN and C cones. Evidence is presented that the original seed of the BN polyhedral particles is a ∼5 nm fullerene-like shell. We propose an idealized model for the seed structures that consists of multiply twinned hexagonal (h-)BN crystals containing a screw dislocation. Thi...

The assembly of nanosheets/nanoplates into three-dimensional hierarchical superstructures brings unexpected properties and unique applications. However, to organize borate nanostructures into ordered superstructures is still a great challenge. Herein, uniform hierarchical laminar priceite (Ca4B10O19·7H2O) superstructures were synthesized via a facile hydrothermal route, in the absence of any templates, surfactants, or capping reagents. The as-prepared hierarchical laminar Ca4B10O19·7H2O superstructures containing rhombic nanosheets were formed by the dissolution–recrystallization controlled growth and subsequent hydrothermal self-assembly and could also be further disassembled into the rhombic nanosheets by hydrothermal treatment over time. The superstructures exhibited transmittance vibrational bands concentrating on the wavenumber range 1750–450 cm–1, lost weight continuously within the temperature range 125–586 °C and kept constant weight thereafter, and demonstrated weak absorptions within the wavelen...

Using pre-existing ZnO nanowires as lattice-matched templates, we have systematically studied the catalyst-free regrowth of ZnO nanostructures in a chemical vapor deposition (CVD) system. Because the templates (or crystal seeds) provided nanoscale preferential nucleation sites for the subsequent growth, changing ZnO supersaturation and growth temperature led to distinct growth modes, from nonepitaxy to homoepitaxy and from axial to radial epitaxy. The perfect borderless homoepitaxial ZnO nanostructures demonstrate the inherent growth behaviors that were especially researched with the help of their position-dependent optical properties. Neither the self-catalyst vapor–liquid–solid (VLS) growth mechanism nor the defects-induced growth mechanism could explain most of these homoepitaxial growth modes. Instead, two-dimensional nucleation and step propagation model based on avapor–solid (VS) scenario was suggested and all these phenomena were well interpreted. In addition, our work presents a very convenient an...

Y2O3:Eu3+ phosphors with 3-dimensional assembled gear-shaped submicrostructure were successfully synthesized through a controlled solvothermal approach followed by a subsequent heat treatment, without using any catalyst or template. These gear-shaped prisms expressed pretty good size distribution. Besides, the possible formation mechanism of the gear-shaped prisms was discussed in brief. Furthermore, their photoluminescence (PL) properties were investigated. The results indicated that the gear-shaped prism samples showed the strongest red emission corresponding to D-5(0) -> F-7(2) transition (609 nm) among the synthesized samples, implying better photoluminescence property of this sub-microstructure with ordered arrays, and suggesting potential application in optoelectronics, such as for fluorescent lamps and flat panel devices application, etc. (C) 2011 Elsevier Masson SAS. All rights reserved.

A novel solution-controlled self-assembly process has been developed to fabricate nanorod assembled ZnO hollow spheres without adding any structure-directing agents and templates, and as-prepared hollow samples with size about 5 mu m are constructed by the radially oriented single-crystalline nanorods with length and diameter of about 1.5 mu n and 80 nm, respectively. The investigation on the evolution formation reveals that water was critical to control the assembly of the fresh formed nanocrystallites, and hollowing formation was proved to be the Ostwald ripening process by tracking the structures of the products at different reaction stages. Scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy were used to characterize the structure of synthesized products, and gas-sensing properties investigation shows that the nanorod-assembled hollow spheres exhibit high gas response to formaldehyde at the optimum working temperature of 400 degrees C.

In this paper, a series of MFe 2 O 4 (M=Mg, Co, Ni, Zn) hollow spheres are successfully prepared by hydrothermal treatment of the mixed solution of glucose, Fe 3+ and M 2+ and a subsequent calcination process. After the calcination process, the carbon core of the hydrothermally prepared composite carbon spheres was removed and the metal components were transformed to pure phase ferrites. The final products (ferrite hollow spheres) were characterized using X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy and the magnetic properties were evaluated using a SQUID magnetometer.

Silicon nanowires (SiNWs) were grown at low temperatures close to metal silicon eutectic point on a silicon substrate using gold catalyst coupled with assistance of the aluminum anodic oxide template. Either a vapor–solid–solid (VSS) growth process below metal silicon eutectic temperature or a vapor–liquid–solid (VLS) process at slightly higher temperatures was observed. The transmission electron microscopy coupled with both the X-ray energy dispersive spectroscopy and the selected area electron diffraction was adopted to characterize the SiNWs. Although the mechanism triggering the VSS process is still not clear, both the geometric and morphological characteristics of the SiNWs grown by the VSS process are discussed and compared with the SiNWs grown by the VLS process. The VSS SiNWs have a much slower growth rate (less than 100 nm/h), a smaller and more uniform diameter (in the range of 15.22 nm) due to a much slower rate of silicon diffusion and much smaller amount of silicon (6.8 wt.%) dissolved in the solid nanocatalyst.

A facile synthesis procedure based on chemical vapor deposition (CVD) process has been developed to fabricate carbon nanotubes (CNTs) with controlled diameters and high yields utilizing Fe-containing ordered hexagonal mesoporous silicas (HMSs) such as MCM-41 and SBA-15 having varied pore sizes as the catalysts as well as the templates. It is found that unlike Fe/HMS catalysts prepared by co-precipitation method, samples prepared by the impregnation method gave rise to multi-wall CNTs with uniform diameters, which were largely dictated by the pore size of the Fe/HMS catalysts. Among these uniform MWCNTs, sample with a larger diameter (≥ 8 nm) was found to be more favorable as support for Pt catalyst, leading to a homogeneous dispersion of metal nanoparticles. Consequently, the Pt/CNT electrocatalysts so prepared gave rise to superior methanol oxidation activities as well as tolerances for CO poisoning compared to Pt supported on commercial single-wall CNT (Pt/SWCNT) and XC-72 activated carbon (Pt/XC-72) having a similar metal loading.

Mesoporous silicas and Fe-SiO{sub 2} with worm-like structures have been synthesized using a room temperature ionic liquid, 1-hexadecane-3-methylimidazolium bromide, as a template at a high aging temperature (150-190 {sup o}C) with the assistance of NaF. The hydrothermal stability of mesoporous silica was effectively improved by increasing the aging temperature and adding NaF to the synthesis gel. High hydrothermally stable mesoporous silica was obtained after being aged at 190 {sup o}C in the presence of NaF, which endured the hydrothermal treatment in boiling water at least for 10 d or steam treatment at 600 {sup o}C for 6 h. The ultra hydrothermal stability could be attributed to its high degree of polymerization of silicate. Furthermore, highly hydrothermal stable mesoporous Fe-SiO{sub 2} has been synthesized, which still remained its mesostructure after being hydrothermally treated at 100 {sup o}C for 12 d or steam-treated at 600 {sup o}C for 6 h. -- Graphical abstract: Worm-like mesoporous silica and Fe-SiO{sub 2} with high hydrothermal stability have been synthesized using ionic liquid 1-hexadecane-3-methylimidazolium bromide as a template under the assistance of NaF at high temperature. Display Omitted Research highlights: {yields} Increasing aging temperature improved the hydrothermal stability of materials. {yields}Addition of NaF enhanced the polymerizationmore » degree of silicates. {yields} Mesoporous SiO{sub 2} and Fe-SiO{sub 2} obtained have remarkable hydrothermal stability.« less

Single-layered porous silica films were prepared on polyethylene terephthalate (PET) substrates as antireflection coatings for efficient, large-scale flexible optoelectronic devices. Cetyltrimethylammonium bromide (CTAB)-templated synthesis was employed to form porous silica films. Without using high temperature treatment, CTAB was removed by washing in water to create a porous structure in the films. To spin-coat on PET substrates, contact angle between silica sol and PET surface was measured to optimize the molar ratio of the solution. Pore size and surface sharpness were estimated using atomic force microscope data. The average reflectance of as-prepared AR coatings on PET substrates was ≤ 2%.

NiO film with sandwich-like morphology is fabricated on nickel foam by a simple ammonia-evaporation process. Ammonia plays a major role in controlling the final geometry during this template- and surfactant-free synthesis. The obtained NiO film is constructed by regular triangular prisms with side length of 500 nm. Each triangular prism is self-assembled by single crystalline platelets. As an anode for lithium ion battery, this NiO film electrode exhibits high discharge capacity and excellent cycling performance. The reversible capacity of the sandwich-like NiO film sustains 400 mAh g−1 even after 50 cycles at 2 C, much higher than that of the dense NiO film prepared by eletrodeposition (198 mAh g−1). The high rate capability and reversibility of this NiO film can be attributed to its unique sandwich-like architecture.

The present work reports the exploitation of starch as a macromolecular matrix in the domain of ‘green’ bio-nanotechnology. The differential templating attributes of starch under ambient aging and sonication for biomimetically generated silver nanoparticles were investigated. Morphology-directing action of the starch-bioreductant (i.e., Mesua ferrea Linn. leaf aqueous extract, adjusted to basic pH) complex resulted in a branched silver structure (∼440 nm, along the long axis with branch average diameter of 11.5 nm) upon aging for 24 days. Starch assisted spherical silver nanoparticles (average diameter, 5.4 nm) were obtained under sonication parameters of 3 min, 0.5 cycles at 60% amplitude, optimized through response surface methodology. Evaluation of phytotoxicity on Cucumis sativus , compromise on amplification of a 263 base pair mammalian DNA sequence in polymerase chain reaction (PCR) and anti-microbial potency demonstrated differential action of the carbohydrate templated aged and sonicated silver nanoparticles at the bio-interface.

This paper describes the preparation of size-controlled CdS nanoparticles in block copolymer micelles and the formation of composite particles of the CdS nanoparticles and polymers. Uniformly sized CdS nanoparticles having various color emission spectra were successfully synthesized. Moreover, composite Janus particles, unidirectionally stacked lamellae and onion particles were formed by combination of CdS nanoparticles and polymer blend or block copolymer systems. This approach provides a simple route for preparation of functional organic/inorganic composite particles.

High quality three-dimensionally ordered macroporous (3DOM) nickel photonic crystals (PCs) are fabricated using the polystyrene template-assisted electrodeposition method on nickel alloy substrate. The Ni2+ in solution will firstly arrive in the electrode (nickel alloy substrate) and occupy the interstices among the PS template spheres; when enlarge the deposition time to 5 min, 3DOM nickel PCs will be achieved. The 3DOM nickel PCs grow firmly on the substrate due to the similar bounds between the PCs and substrate. Excellent mechanical properties are observed in the 3DOM nickel PCs, which may promote the practical applications of PCs.

The synthesis and full characterisation of pure and Mn-doped polycrystalline zinc oxide nanorods with tailored dopant content are obtained via a single source molecular precursor approach using two Schiff base type coordination compounds is reported. The infiltration of precursor solutions into the cylindrical pores of a polycarbonate template and their thermal conversion into a ceramic green body followed by dissolution of the template gives the desired ZnO and Mn-doped ZnO nanomaterial as compact rods. The ZnO nanorods have a mean diameter between 170 and 180 nm or 60–70 nm, depending on the template pore size employed, comprising a length of 5–6 μm. These nanorods are composed of individual sub-5 nm ZnO nanocrystals. Exact doping of these hierarchically structured ZnO nanorods was achieved by introducing Mn(II) into the ZnO host lattice with the precursor complex Diaquo-bis[2-(meth-oxyimino)-propanoato]manganese, which allows to tailor the exact Mn(II) doping content of the ZnO rods. Investigation of the Mn-doped ZnO samples by XRD, TEM, XPS, PL and EPR, reveals that manganese occurs exclusively in its oxidation state + II and is distributed within the volume as well as on the surface of the ZnO host.

Lanthanum oxycarbonate (La 2 O 2 CO 3 ) hollow microspheres with novel porous architectures were successfully fabricated by a simple one-pot hydrothermal treatment of an aqueous solution containing glucose, La(NO 3 ) 3 ·6H 2 O, and subsequent calcination. The as-prepared La 2 O 2 CO 3 porous hollow spheres are composed of nanoparticles with a mean particle size of 15 nm. Carbon microspheres act as not only templates but also carbon sources for the formation of La 2 O 2 CO 3 hollow spheres. Interestingly, the as-prepared La 2 O 2 CO 3 hollow spheres show a green emission band under UV excitation, which may be used as fluorescent biological labels.

Cuprous oxide (Cu 2 O) dendrites were prepared by simple hydrothermal route at two different temperatures using starch as reducing and stabilizing agent. Scanning Electron Microscopy (SEM) revealed the alterations in morphology with reaction temperature and time. The spherical nanoparticles obtained at lower reaction temperature self-assembled into distinct dendritic nanostructures at high temperature. The mechanism of formation of dendrite over the polysaccharide template has been discussed. Transmission Electron Microscopy (TEM) revealed that the crystalline size of these dendrites in one dimension is about 50 nm. The nanoparticles were characterized by UV–vis and photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), FT-IR and Thermal Gravimetry Analyzer (TGA). Impedance analysis of the nanostructures showed conductivity to be a function of temperature.

Bismuth titanates, Bi 2 Ti 2 O 7 (BIT), with well-defined spherical structures were synthesized by a facile hydrothermal process without the use of any surfactant or template. XRD and SEM studies have shown that spheres could be fabricated in high yields by simply manipulating the concentrations of hydroxide ions. In this case, hydroxide ions seem to play a pivotal role in controlling the formation of seeds and growth rates of the BIT particles. On the basis of structural analysis of samples obtained at different concentrations of OH − , we also proposed a plausible mechanism to account for the formation of these distinctive morphologies under different conditions. The as-prepared BIT microspheres with good stability exhibited higher photocatalytic activities in the degradation of Rhodamine B (RhB) under visible light irradiation than that in commercial P25 TiO 2 . Furthermore, the enhanced photocatalytic performance for RhB degradation was also investigated with assistance of a small amount of H 2 O 2 .

In this communication, a facile and green method is introduced for the preparation of porous starch (PS), citric acid-modified PS (CAPS) and porous ZnO. PS was created by replacing ice crystals in frozen starch gel with selected solvent using a solvent exchange technique. The porosity of PS was greatly affected by the ethanol/water volume ratios. PS was further modified with citric acid (CA) in order to preserve or maintain its porous state, especially upon contact with aqueous solution. CAPS was subsequently used as a structure-directing agent to prepare ZnO with a porous network structure. The thus obtained PS, CAPS and porous ZnO may find their niche in applications such as adsorbent, structure-directing agents for porous metal oxides or as sensors.

Synthesis of Ag–Pd alloy nanoparticles was carried out with carboxylated cellulose nanocrystals as the scaffolds by reducing metallic cations using NaBH 4 . Alloy particles with a size less than 10 nm were readily prepared and dispersed well. The average size of alloy nanoparticles decreased as the increasing molar ratio of Ag/Pd. The carboxyl and hydroxyl groups of carboxylated cellulose nanocrystals supplied a coordination effect to adsorb metallic cations and alloy nanoparticles to prevent the aggregation of nanoparticles. The carboxylated cellulose nanocrystals as platforms carrying Ag–Pd alloy nanoparticles were used as labels for electrical detection of DNA hybridization.

An asymmetric two-step anodization process is used to fabricate hierarchical nanoporous anodic alumina templates (HNAATs) with different geometric characteristics. This nanostructure consists of an outer hexagonal lattice of concavities in the interior of which pores grow. The anodization conditions (anodization voltage, and type and concentration of the acid electrolyte) between the first and the second step are considerably varied to obtain different types of templates. Two growth regimes (mild and hard), three types of acid electrolytes (phosphoric, oxalic and sulphuric) and three acid electrolyte concentrations (0.3, 0.2 and 0.1 M) are combined. In addition, the voltage ratio between the second and the first step of the anodization process is ranged from 0.11 to 0.71. By modifying these parameters, it is possible to control the fabrication process and obtain HNAATs with a wide range of morphologies.

Cu nanowire arrays were synthesized via a porous alumina membrane (PAM) template with a high aspect ratio, uniform pore size (120–140 nm), and ordered pore arrangement. The Cu 2 O nanowire arrays were prepared from the oxidization of Cu metal nanowire arrays. The electrochemical deposition potential of Cu metal nanowires (−180 mV vs. SCE) was determined from X-ray diffraction (XRD) patterns. The microstructure and chemical composition of Cu nanowire arrays were characterized using field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD). Results indicate that the Cu/Cu 2 O nanowire arrays assembled into the nanochannel of the porous alumina template with diameters of 120–140 nm. The valence of copper was controlled by the porous alumina template during the annealing process. Copper nanowires transformed to the Cu 2 O phase with the space limitation of the PAM template. Single-crystal Cu 2 O nanowire arrays were also obtained under the template embedded.

Porous one-dimensional Mn2O3 nanostructures have been successfully fabricated via a facile hydrothermal treatment and sequential thermal decomposition without any template or surfactant. By adjusting the ethanol content in the solvent system, nanofibers, nanowires and nanorods nanostructures can be selectively prepared. Moreover, corresponding porous one-dimensional Mn2O3 nanostructures can be obtained by calcination at elevated temperatures. Electron microscopic, Fourier transform infrared spectra and powder X-ray diffraction (XRD) studies were used to characterize the as-prepared products before and after calcination. As a demonstration of potential applications for lithium-ion batteries anode materials, the polycrystalline porous Mn2O3 nanostructures exhibited a large initial discharge capacity and relative poor cycle performance.

Nearly monodisperse hollow α-Fe2O3 microspheres composed of nanoparticles have been successfully synthesized through a facile template-free hydrothermal method. The products were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. It is shown that the hollow α-Fe2O3 microspheres consist of well-aligned α-Fe2O3 nanoparticles with a mean diameter of about 15 nm. This facile reaction route presents an efficient method for mass production of monodisperse hollow magnetic nanomaterials. The final α-Fe2O3 microspheres exhibit special magnetic properties with a small remnant magnetization of 0.09 emu g−1 and a high coercivity of 1121.67 Oe at room temperature.

Arrays of Co-doped ZnO nanowires were fabricated by electrodeposition of Zn 2+ and Co 2+ into an anodic aluminum oxide template followed by post-oxidation annealing in an Ar/O 2 mixed atmosphere. Transmission electron microscopy showed that the nanowires were uniform with a diameter of about 75 nm. Significant differences in the crystalline structures of samples annealed at different temperatures were observed. Magnetization measurements showed that the Co-doped ZnO nanowires exhibit room-temperature ferromagnetism that changed with the annealing temperature.

Without any catalyst or pressure, bulk non-graphitizing carbon does not exhibit any change in its atomic order (or graphitize) even at 3000 °C. We propose a route for significant graphitization in polymer-derived disordered carbon materials at moderate temperatures by pre-aligning the precursor polymer chains. Accordingly, we employ a template-based fabrication process, where the capillary forces align the polyfurfuryl alcohol chains in the form of nanowires with diameter from 100–200 nm. The nanowires are pyrolyzed at temperatures ranging from 600 °C to 2000 °C and characterized with transmission electron and Raman microscopy as well as electrical conductivity measurements. The observed significant change in atomic rearrangement is explained by the alignment of precursor chains during the templated synthesis.

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 (

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.

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.

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.

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.

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.

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...