The bis(p-sulfonatophenyl)phenylphosphine-assisted synthesis and phase transfer of ultrafine gold nanoclusters

The behavior of Couette flow of nanofluids composed of negatively-charged nanoparticles dispersed in aqueous NaCl solutions is studied theoretically. The equation for calculating the Couette flow velocity profiles is derived. The induced electric fields and velocity profiles are calculated as a function of key parameters including nanoparticle size and volume fraction. We have found for the first time that the velocity profile of nanofluids containing charged nanoparticles deviates significantly from the classical linear velocity profile for Couette flow. This previously unseen flow phenomenon is attributed to the dominance of the electric field strength induced by the flow of charged nanoparticles. This new mechanism of nanoparticle-induced microfluidic transport could lead to novel microfluidic and tribological applications.     

Light-driven synthesis of hollow platinum nanospheres

Hollow platinum nanospheres that are porous and have uniform shell thickness are prepared by templating platinum growth on polystyrene beads with an adsorbed porphyrin photocatalyst irradiated by visible light.     

Sonochemical synthesis of hollow PbS nanospheres

PbS hollow nanospheres with diameters of 80-250 nm have been synthesized by a surfactant-assisted sonochemical route. The nanostructures were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), (high-resolution) transmission electron microscopy [(HR)TEM], and scanning electron microscopy (SEM) images. Structural characterization indicates that shells of the hollow spheres are composed of PbS nanoparticles with diameters of about 12 nm. The formation of the hollow nanostructure was explained by a vesicle-template mechanism, in which sonication and surfactant play important roles. Furthermore, uniform silica layers were successfully coated onto the hollow spheres via a modified St?ber method to enhance their performance for promising applications.     

One-pot synthesis of hollow superparamagnetic CoPt nanospheres

Hollow metal nanospheres are of interest for a variety of academic and technological applications, including drug delivery, catalysis, plasmonics, and lightweight structural composites. Despite recent advances in synthesizing metal nanostructures with controlled morphologies, there are very few reports of hollow bimetallic nanospheres, although such systems promise to offer advantages over single-metal systems. Here, were report a one-pot synthetic strategy for accessing hollow CoPt nanospheres with a Co-Pt alloy structure. The approach utilizes an in situ Co template and exploits galvanic displacement reactions to selectively dissolve the Co core while depositing a Pt shell. The combination of reducing conditions and a polymer stabilizer appears to allow the Co and Pt to co-reduce and form a Co-Pt fcc alloy phase with a morphology that is templated by the sacrificial Co core. The hollow CoPt nanospheres, which show magnetic hysteresis at low temperatures, are thermally stable up to 300 degrees C. The approach, which adds to a growing toolbox of reactions that yield morphologically controlled magnetic CoPt and FePt nanomaterials, is likely to be general for a variety of alloy systems.     

Biomimetic synthesis of calcium-strontium apatite hollow nanospheres

In this work, calcium-strontium apatite (Sr-HA) hollow nanospheres were synthesized by a facile biomimetic method. The structure and property of Sr-HA were characterized by FESEM, TEM, HRTEM, XRD and FT-IR spectroscopy. The influences of different ratios of calcium and strontium on the morphologies of the Sr-HA products were investigated. The experimental results revealed that the hollow spherical Sr-HA, with a size of 30–120 nm in diameter, could be synthesized when the molar ratio of Ca/Sr was 1:1. The possible formation mechanism of the hollow Sr-HA was proposed. The drug release experiments indicated that the hollow spherical Sr-HA had the property of sustained release.     

Large-scale synthesis of bismuth hollow nanospheres for highly efficient Cr(vi) removal

Bismuth hollow nanospheres were successfully synthesized via a facile solvothermal method and exhibit highly efficient Cr(vi) removal capacities in a wide pH range (2-11).     

Surfactant-assistant and facile synthesis of hollow ZnS nanospheres

Small and monodisperse ZnS hollow nanospheres with outer diameter ranging from 60 to 70 nm and wall thickness of 15-20 nm were fabricated in a large scale by a simple surfactant polyethylene glycol (PEG) assisted method. The diameter and the wall thickness of the hollow nanospheres could be controlled by manipulating the amount of PEG and the aging time, respectively. Moreover, the wall of these hollow nanospheres is very compact. The product was characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), UV-vis spectrum and fluorescence spectroscopy. The photocatalytic activity of as-prepared ZnS hollow nanospheres was also evaluated by using methyl orange (MO) as a model organic compound and the result revealed that their photocatalytic activity is a little lower than that of Degussa P25 TiO(2) but better than that of ZnS nanocrystals prepared by literature method. Furthermore, a rational mechanism to the formation and evolution of the products is proposed.     

The synthesis of ZnS hollow nanospheres with nanoporous shell

ZnS hollow nanospheres with nanoporous shell were successfully synthesized through the evolvement of ZnO nanospheres which were synthesized by hydrothermal method with poly (sodium-p-styrene sulfonate) (PSS) as surfactant at low temperature. The as-synthesized samples were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), UV/vis spectrum and N₂ adsorption. The results showed that the shell of as-synthesized ZnS hollow structure was composed of many fine crystallites and had a nanoporous structure with pore diameter about 4 nm demonstrated by N₂ adsorption/desorption isotherm. The sample possessed efficiency of photocatalytic degradation on X-containing (X=Cl, Br, I) organic pollutants.     

A cationic surfactant-induced selective etching strategy for the synthesis of organosilica hollow nanospheres

The simple and effective synthesis of well-defined organosilica hollow nanospheres (OHNSs) for fundamental research and practical applications is still a significant challenge. In this work, a facile “cationic surfactant-induced selective etching” strategy was developed for the fabrication of hollow thiocyanatopropyl silsesquioxanes (thiocyanatopropyl-SQ), mercaptopropyl silsesquioxane (mercaptopropyl-SQ) from cyanoethyl-SQ@thiocyanatopropyl-SQ and cyanoethyl-SQ@mercaptopropyl-SQ, respectively. The experiments demonstrated that cetyltrimethylammonium bromide (CTAB) had remarkable influence on the formation of hollow structure and could accelerate the etching process significantly. A formation mechanism initiated by the adsorption of cationic surfactant followed by the etching of inner core with NH₃·H₂O was proposed. Hollow thiocyanatopropyl-SQ and mercaptopropyl-SQ with various shell thickness could be prepared by manipulating the amount of CTAB. And large-scale OHNSs were obtained at appropriate concentration of CTAB through this strategy. Moreover, this strategy might be further extended to fabricate OHNSs with other worthy functional groups.

Open image in new window

     

One-pot synthesis and bioapplication of amine-functionalized magnetite nanoparticles and hollow nanospheres

To demonstrate their applications in biological and medical fields such as in immunoassays, magnetic separation of cells or proteins, drug or gene delivery, and magnetic resonance imaging, the template-free syntheses of water-soluble and surface functionalized magnetic nanomaterials have become essential and are challenging. Herein, we developed a facile one-pot template-free method for the preparation of amine-functionalized magnetite nanoparticles and hollow nanospheres by using FeCl(3)6 H(2)O as single iron source. These magnetic nanomaterials were characterized by TEM, SEM, XRD, and FTIR technologies. Their magnetic properties were also studied by using a superconducting quantum interference device (SQUID) magnetometer at room temperature. Then the amine-functionalized magnetite nanoparticles were applied to immunoassays and magnetic resonance imaging in live mice.     

Facile synthesis, structure, and luminescence properties of Pt(diimine)bis(arylacetylide) chromophore-donor dyads

The luminescent complex Pt(dpphen)bis(arylacetylide) complex (1) (dpphen = 4,7-diphenylphenanthroline and arylacetylide = 4-ethynylbenzaldehyde) has been synthesized and characterized structurally and spectroscopically. Complex 1 has been employed in the synthesis of donor-chromophore (D-C) dyads through Schiff base condensations of different anilines to give imine-linked dyads 2-4 and through imine reduction with borohydride, to give the corresponding amine-linked dyads 2a-4a. Crystal structure determinations of 1-4 and 4a establish a distorted square-planar geometry around the Pt(II) ion in each system with cis arylacetylide ligands and a diimine-constrained N-Pt-N bond angle of ca. 79.5 degrees. Complex 1 is strongly emissive having a relative quantum yield (phi) of 36% and an excited-state lifetime of 3.1 micros. In accord with the notion of photoinduced electron transfer from the aniline-based donor to the photoexcited chromophore, the emission of dyads 2-4 and 2a-4a is effectively quenched in all solvents tested. The intense absorption at 400 nm (30000-70000 L/mol.cm) for 2 and 2a has been assigned as an intraligand pi-pi* transition, whereas the lowest-energy transitions for all other dyads correspond to Pt-to-pi(diimine) MLCT transitions. Although the dyads can be synthesized in a facile manner, photolysis experiments reveal that both the imine and amine linkages are photochemically unstable, resulting in hydrolysis and regeneration of the aldehyde-containing chromophore 1.     

One-step pyrolysis process to synthesize dispersed Pt/carbon hollow nanospheres catalysts for electrocatalysis

An effective method for loading Pt nanoparticles on monodispersed hollow carbon nanospheres by one-step pyrolysis of polystyrene spheres (PS) adsorbed with platinum (IV) ions was developed. The polystyrene spheres were firstly enwrapped with a layer of sucrose and cetyltrimethyl ammonium bromide (CTAB) micelles. Adsorption of platinum (IV) ions onto the polystyrene spheres was carried out via electrostatic interaction between the negatively charged platinum salt and the positively charged amino group in the CTAB. Pyrolysis of the PS-Pt (IV) precursors at 600 °C under nitrogen atmosphere resulted in the simultaneous decomposition of the sucrose to carbon and the adsorbed platinum complex to metallic Pt. During this process the polystyrene spheres was removed and hollow sphere of PtC formed. Nanocomposites of hollow carbon nanospheres with different platinum loading were synthesized and their electrocatalytic activity was evaluated using methanol as a model molecule. Results showed that the as-prepared hollow carbon nanospheres supported platinum catalysts have high electrocatalytic activity and long-term stability towards the oxidation of methanol. The present method is promising for the fabrication of carbon supported platinum catalysts for the direct methanol fuel cell.     

Highly active catalysts: Double‐shelled hollow nanospheres with tiny Pt NPs

A facile strategy was reported to fabricate a novel Pt‐based metal oxide double‐shelled hollow nanospheres (MDSHs), which avoided the traditional tedious procedures. It was attractive that the formation mechanism of DSHs involved redeposition of etch‐released silica species and self‐assembly of metal oxide units. To verify the successful synthesis and structure features of Pt‐LCDSHs catalyst, the as‐prepared samples were characterized by several techniques, such as SEM, N₂ adsorption–desorption isotherm analysis, TEM, EDX, XRD and XPS. Results indicated that all of MDSHs possessed double‐shelled structures with both the inner and outer shells composing of metal oxide units. Interestingly, the metal oxide of the DHSs could offer abundant active points for Pt NPs and the space between the double shells also could be filled with Pt NPs. What's more, compared with the pure samples, the Pt‐embedded La₂O₃‐CeO₂‐DSHs exhibited the highest catalytic performance (6.58 × 10^?3 min^?1) and good reusability with a conversion of 94% even after eight cycles, which were evaluated by means of the reduction of 4‐nitrophenol monitored by UV–vis spectra. Finally, a possible reaction mechanism for the reduction reaction on Pt‐based La₂O₃‐CeO₂‐DSHs was also proposed.     

Sonochemical preparation of hollow nanospheres and hollow nanocrystals

Ceramic hollow spheres of MoS2 and MoO3 were obtained by sonochemical synthesis of MoS2 and MoO3 templated on silica nanoparticles (diameters 50-500 nm) followed by acid etching to remove the silica core. The resulting hollow materials have been characterized by elemental analysis, XPS, SEM, TEM, optical absorption, and hydrodesulfurization (HDS) studies. The TEM studies on the hollow ceramic materials indicate the formation of dispersed free spheres with a hollow core. The hollow materials obtained from thermally treated MoS2/SiO2 (450-700 degrees C) show the formation of layered MoS2 (lattice fringes approximately 6.2 A) with a wall thickness of 6-8 layers. The MoS2 hollow spheres are extremely active catalysts for the HDS of thiophene. Hollow spheres of MoO3 are prepared in a similar fashion. Surprisingly, upon heating, hollow crystals of MoO3 with sharp-edged truncated cubes containing inner voids are formed from the initial spheres.     

A block copolymer micelle template for synthesis of hollow calcium phosphate nanospheres with excellent biocompatibility

We report synthesis of hollow calcium phosphate (CaP) nanospheres with high surface area by using block copolymer micelles as templates. The obtained CaP nanospheres exhibit very high biocompatibility, showing great promise for intracellular bio-applications in future.     

A convenient one-pot synthesis of o-phenylene bis(diphenylphosphine)

The reaction between $\text{o}$-difluorobenzene and sodium diphenylphosphide in liquid ammonia provides a convenient synthesis of the title compound.     

Controllable synthesis and photoluminescence of single-crystalline BaHfO3 hollow micro- and nanospheres

This paper presents a facile hydrothermal route to synthesize monodispersive and single-crystalline BaHfO(3) hollow micro- and nanospheres in a concentrated basic environment. The hollow spheres were size tunable from submicrometer to nanoscale by simply adjusting the base concentration at a suitable temperature. The base concentration played the key role on forming BaHfO(3) hollow spheres. Detailed investigations on base concentration, reaction temperature, and duration indicated that the formation of BaHfO(3) hollow spheres was driven by Ostwald ripening process. Because of the abundance of defects, the as-prepared BaHfO(3) hollow nanospheres exhibited a blue light emission under UV-light excitation at room temperature. Calcination led to the photoluminescence declination due to the decrease of defects.     

Difunctional heterocycles: A convenient one pot synthesis of novel bis(benzoxazoles) from bis(o-aminophenols)

New bis(benzoxazoles) 14 and 17 have been synthesized in excellent yields from the corresponding bis(o-aminophenols) by refluxing with triethyl orthoformate. 6,6′-Bis(benzoxazole) ( 14 ) has also been prepared utilizing Gold's reagent. Compound 14 is inert to Reissert reaction conditions. However, the Reissert reaction on 5,5′-bis(benzoxazole) (17) led to ring opened product 20 .     

Templated synthesis of imine-based covalent organic framework hollow nanospheres for stable potassium-ion batteries

Covalent organic frameworks (COFs), as highly tunable porous crystalline materials, have promising applications in potassium-ion batteries (PIBs) due to their abundant charge carrier transport channels and excellent structural stability. However, the excessive stacking of interlayer electron clouds makes it difficult to expose internal active sites. Strategies to design functional COFs with controllable morphology and copious active sites are promising but still challenging. Herein, by utilizing the condensation between 1,3,5-triformylbenzene (TFB) and p-phenylenediamine (PPD) and using amino-modified SiO₂ nanospheres as templates, we synthesize core-shell NH₂-SiO₂@TP-COF. Through NaOH etching of NH₂-SiO₂@TP-COF, we obtain imine-based TP-COF hollow nanospheres, which shows excellent potassium storage performance when applied to the anode for PIBs. Ex-situ analysis and density functional theory calculations reveal that CN groups and benzenes are active sites for K⁺ storage.