A novel method for the templated synthesis of homogeneous samples of hollow carbon nanospheres from cellulose chars

A novel method for the production of homogeneous samples of hollow carbon nanospheres is reported from cellulose, an inexpensive and renewable precursor. The nanospheres are of diameter 50 nm, graphitic wall thickness 5-10 nm, and can easily be produced in several hundred milligram batches. The nanospheres are derived from the laser pyrolysis of a nickel chloride templated cellulose char via open Ni-core shells.     

Superior Electrochemical Properties of Nanofibers Composed of Hollow CoFe2O4 Nanospheres Covered with Onion‐Like Graphitic Carbon

Nanofibers composed of hollow CoFe₂O₄ nanospheres covered with onion‐like carbon are prepared by applying nanoscale Kirkendall diffusion to the electrospinning process. Amorphous carbon nanofibers embedded with CoFe₂@onion‐like carbon nanospheres are prepared by reduction of the electrospun nanofibers. Oxidation of the CoFe₂‐C nanofibers at 300 °C under a normal atmosphere produces porous nanofibers composed of hollow CoFe₂O₄ nanospheres covered with onion‐like carbon. CoFe₂ nanocrystals are transformed into the hollow CoFe₂O₄ nanospheres during oxidation through a well‐known nanoscale Kirkendall diffusion process. The discharge capacities of the carbon‐free CoFe₂O₄ nanofibers composed of hollow nanospheres and the nanofibers composed of hollow CoFe₂O₄ nanospheres covered with onion‐like carbon are 340 and 930 mA h g^?1, respectively, for the 1000th cycle at a current density of 1 A g^?1. The nanofibers composed of hollow CoFe₂O₄ nanospheres covered with onion‐like carbon exhibit an excellent rate performance even in the absence of conductive materials.     

Polarized Raman Spectra VIII. Ramam Intensities of Anthracene Excited by Different Laser Light

An Ar-Kr ion laser was used to excite the Raman spectrum of powdered anthracene with two laser lines of 4880 and 6471 Å. There are significant differences in the intensity distribution in these two Raman spectra. These differences can be best explained by considering that Raman intensities are contributed by two allowed excited states of anthracene, and their contributions depend upon the laser frequency. From these Raman spectra, it is also possible to infer the vibrational structures in the higher energy, structureless excited state of anthracene.     

High performance pliable supercapacitor fabricated using activated carbon nanospheres intercalated into boron nitride nanoplates by pulsed laser ablation technique

Pliable supercapacitor, yielding specific capacitance (C_s) and energy density as high as 348 F g⁻¹ and 48.3 Wh Kg⁻¹ respectively was fabricated using modified activated carbon electrodes. The nanospheres of activated carbon (AC) were anchored on the nanoplates of boron nitride (BN) by employing the facile technique of pulsed laser ablation in liquid (PLAL) using 532 nm focused laser beam. Four different variants of electrode materials were synthesized by varying the weight percentage (1%, 3%, 5% and 10%) of BN in AC in the PLAL precursor solution. The morphological characteristics, the elemental composition and the structural analysis of the synthesized electrode materials were studied respectively by FESEM, XPS and XRD. The morphological studies indicated that the PLAL synthesis of the electrode materials resulted in proper intercalation of carbon nanospheres into BN nanoplates, which resulted in the observed enhanced performance of the fabricated supercapacitor. Four supercapacitors in this work were fabricated using the four variants of synthesized electrode materials in conjunction with gel polymer electrolyte (GPE). GPE are well known for their non-corrosive nature and best sealing ability to avoid any leakage that results in increasing the cycle life of the device. The performance of the fabricated supercapacitors was evaluated using cyclic voltammetry (CV), galvanostatic charge discharge (GCD) measurement and electrochemical impedance spectroscopy (EIS). The results indicate that the supercapacitor fabricated using 3% BN in AC as electrode material manifested the best specific capacitance and energy density. Also it was found that the supercapacitor maintained 85% of its initial capacitance even after 5000 charge/discharge cycles.     

Core‐shell structured magnetic mesoporous carbon nanospheres derived from metal‐polyphenol coordination polymer‐coated Fe3O4 and its application in the enrichment of phthalates from water samples

In this work, core‐shell structured magnetic mesoporous carbon nanospheres were fabricated from the carbonization of metal‐polyphenol coordination polymer‐coated Fe₃O₄ nanoparticles. The preparation method is simple, fast, versatile, and easy to scale up. Magnetic mesoporous carbon nanospheres exhibit a high specific surface area, high superparamagnetism, and high adsorption efficiencies for phthalates. Four phthalates were extracted from aqueous solutions by using magnetic mesoporous carbon nanospheres via magnetic solid phase extraction. Subsequent analysis was performed by using high‐performance liquid chromatography with ultraviolet detection. The analytical method has good linearity in the concentration range of 1–200 ng/mL for diethyl phthalate, diisobutyl phthalate, and dicyclohexyl phthalate, and 3–200 ng/mL for dipropyl phthalate. The limits of detection were in the range of 0.10–0.62 ng/mL. Compared with previous methods, this method has a lower detection limit, wider linearity range, and faster adsorption and desorption rates. The results indicate that magnetic mesoporous carbon nanospheres are suitable for the enrichment of hydrophobic substances from aqueous solutions.     

Surface modification of Mitoxantrone-loaded PLGA nanospheres with chitosan

The purpose of this research was to develop polylactic-co-glycolic acid (PLGA) nanospheres surface modified with chitosan (CS). Mitoxantrone- (MTO-) loaded PLGA nanospheres were prepared by a solvent evaporation technique. The PLGA nanospheres surface was modified with CS by two strategies (adsorption and covalent binding). PLGA nanospheres of 248.4 ± 21.0 nm in diameter characterized by the laser light scattering technique, scanning electron microscopy (SEM) are spherical and its drug encapsulation efficiency is 84.1 ± 3.4%. Zeta potential of unmodified nanospheres was measured to be negative −21.21 ± 2.13 mV. The positive zeta potential of modified nanospheres reveals the presence of CS on the surface of the modified nanospheres. Modified nanospheres were characterized for surface chemistry by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR). FT-IR spectra exhibited peaks at 3420 cm⁻¹ and 1570 cm⁻¹, XPS spectra shows the N 1s (atomic orbital 1s of nitrogen) region of the surface of the nanospheres, corresponding to the primary amide of CS. In vitro drug release demonstrated that CS-modified nanospheres have many advantages such as prolonged drug release property and decreased the burst release over the unmodified nanospheres, and the modified nanospheres by covalent binding method could achieve the release kinetics of a relatively constant release. These data demonstrate high potential of CS-modified PLGA nanospheres for the anticancer drug carrier.     

Uniform silver nanoparticles on tunable porous N‐doped carbon nanospheres for aerobic oxidative synthesis of aryl nitriles from benzylic alcohols

Tunable N‐doped carbon nanospheres from sucrose as carbon source and Tris(2‐aminoethyl)amine (TAEA) as nitrogen source by a simple and easily reproducible method were prepared. It was demonstrated that the tunable N‐doping of carbon spheres could be realized by altering the ratio of TAEA in the raw materials. The content of doped nitrogen, surface area, pore volume and pore size of carbon nanospheres were increased with the increasing of TAEA amount in the hydrothermal process. Prepared N‐doped carbon nanospheres act as solid ligand for anchoring of Ag NPs which generated via chemical reduction of Ag ions. Benzylic alcohols and aldehydes were converted into the aryl nitriles by using Ag/N‐CS‐1 nanospheres as the catalyst and O₂ as the oxidant, efficiently. This catalyst was stable and could use for 6 successful runs.     

Dual Protection of Sulfur by Carbon Nanospheres and Graphene Sheets for Lithium–Sulfur Batteries

Well‐confined elemental sulfur was implanted into a stacked block of carbon nanospheres and graphene sheets through a simple solution process to create a new type of composite cathode material for lithium–sulfur batteries. Transmission electron microscopy and elemental mapping analysis confirm that the as‐prepared composite material consists of graphene‐wrapped carbon nanospheres with sulfur uniformly distributed in between, where the carbon nanospheres act as the sulfur carriers. With this structural design, the graphene contributes to direct coverage of sulfur to inhibit the mobility of polysulfides, whereas the carbon nanospheres undertake the role of carrying the sulfur into the carbon network. This composite achieves a high loading of sulfur (64.2 wt %) and gives a stable electrochemical performance with a maximum discharge capacity of 1394 mAh g^?1 at a current rate of 0.1 C as well as excellent rate capability at 1 C and 2 C. The improved electrochemical properties of this composite material are attributed to the dual functions of the carbon components, which effectively restrain the sulfur inside the carbon nano‐network for use in lithium–sulfur rechargeable batteries.     

A facile template free synthesis of porous carbon nanospheres with high capacitive performance

Porous carbon nanospheres have been widely used in different fields such as electric devices, catalysts, and water treatment. Here we will introduce a template-free process for the preparation of porous carbon nanospheres starting from a direct 3-aminophenol formaldehyde polymerization in a mixed solution. We identify that the addition of different alcohols, particularly ethanol and n-butanol, is able to change the growth habit of the polymer nanospheres and introduce a favorable inner compositional homogeneity for the preparation of porous structure. After the carbonization of the polymer nanospheres, the obtained porous carbon exhibits promising electrochemical performance when used as electrode material in super capacitor.     

Preparation and properties of nitrogen-containing hollow carbon nanospheres by pyrolysis of polyaniline-lignosulfonate composites

Polyaniline-lignosulfonate composite hollow spheres were synthesized by using one-step unstirred polymerization of aniline in the presence of lignosulfonate. Novel nitrogen-containing hollow carbon nanospheres were prepared by direct pyrolysis of the polyaniline-lignosulfonate composite spheres at different temperatures under a nitrogen atmosphere. Thermal behavior of the polyaniline-lignosulfonate composite spheres was studied by TG-DTG, FTIR and element analyze instruments. The resultant carbon spheres were characterized by SEM, XRD and nitrogen adsorption-desorption measurement. It was found that the pyrolysis products of the polyaniline-lignosulfonate composite spheres were made up of uniform hollow carbon nanospheres with an average diameter of 135 nm. Furthermore, the hollow carbon nanospheres exhibit high BET surface area range from 381.6 m² g⁻¹ to 700.2 m² g⁻¹. The hollow carbon nanospheres could be used as adsorbents of papain. The papain adsorption capacity for the carbon spheres prepared at 1200 °C was up to 1161 mg g⁻¹ at an initial papain concentration of 10 mg mL⁻¹ at 25 °C.     

Bismuth Tellurate Nanospheres and Electrochemical Behaviors of L-Cysteine at the Nanospheres Modified Electrode

Bismuth tellurate nanospheres have been successfully synthesized by a facile hydrothermal route. X-ray diffraction (XRD) shows that the nanospheres are composed of orthorhombic Bi₂Te₂O₇ phase. Scanning electron microscopy (SEM) displays that the diameter of the nanospheres is 100–500 nm. The bismuth tellurate nanospheres (BTS) modified glassy carbon electrode (GCE) has been prepared for the electrochemical detection of L-cysteine (L-CySH). A pair of semi-reversible CV peaks at +0.14 V and–0.84 V, respectively are observed. The BTS modified GCE displays high electrocatalytic activity toward L-CySH and exhibits a linear relationship in the range of 0.0001–2 mM with a detection limit of 0.046 μM in KCl solution. The broad linear range, low detection limit, good reproducibility and stability make the BTS modified GCE valuable for the practical application.     

Unprecedented Charge‐Transfer Complex of Fused Diporphyrin as Near‐Infrared Absorption‐Induced High‐Aspect‐Ratio Nanorods

Charge‐transfer (CT) complexes of near‐infrared absorbing systems have been unknown until now. Consequently, structural similarities between donor and acceptor are rather important to achieve this phenomenon. Herein, we report electron donors such as non‐fused diporphyrin‐anthracene (DP), zinc diporphyrin‐anthracene (ZnDP) and fused zinc diporphyrin‐anthracene (FZnDP) in which FZnDP absorbs in NIR region and permits a CT complex with the electron acceptor, perylene diimide (PDI ) in CHCl₃ exclusively. UV/Vis‐NIR absorption, ¹H NMR, NOESY and powder X‐ray diffraction analysis demonstrated that the CT complex formation occurs by π–π stacking between perylene units in FZnDP and PDI upon mixing together in a 1:1 molar concentration in CHCl₃, unlike non‐fused ZnDP and DP. TEM and AFM images revealed that the CT complex initially forms nanospheres leading to nanorods by diffusion of CH₃OH vapors into the CHCl₃ solution of FZnDP/PDI (1:1 molar ratio). Therefore, these CT nanorods could lead to significant advances in optical, biological and ferroelectric applications.     

Preparation of PTFE Nanosphere with the Assistant of Modified Multi-Walled Carbon Nanotubes

PTFE nanospheres have been obtained with the assistant of different multi-walled carbon nanotubes (MWNTs) by means of a simple preparation method. The results show that the PTFE nanospheres possess the best dispersion stability using the fluorocarbon-modified MWNTs as the assistant. The products are characterized by field-emission scanning electron microscopy and X-ray photoelectron spectroscopy, respectively.     

Water/ionic liquid interfaces as fluid scaffolds for the two-dimensional self-assembly of charged nanospheres

Liquid-liquid interfaces formed between water and ionic liquids serve as fluid scaffolds to self-assemble anionic nanospheres two-dimensionally. When aqueous dispersions of anionic fluorescent polystyrene nanospheres (diameter ～500 nm) are layered on ionic liquids, ordered monolayers are spontaneously formed at the interface. Fluorescent nanospheres are hexagonally packed in the interfacial monolayers, as observed by confocal laser scanning microscopy (CLSM). The adsorption and alignment of nanospheres at the interface are affected by the ionic strength and pH of the aqueous phase, indicating electrostatic interaction as the primary driving force for the self-assembly. CLSM observation of the water/ionic liquid interface reveals that the lower hemisphere of nanospheres is exposed to the ionic liquid phase, which effectively alleviates lateral electrostatic repulsion between charged nanospheres and promotes their close packing. The densely packed monolayer structure of nanospheres is stably immobilized on the surface of CLSM glass dishes simply by rinsing the ionic liquid layer with pure water, probably as a consequence of the gluing effect exerted by imidazolium cations. The fluidic nature of the water/ionic liquid interface facilitates the diffusion and ordering of nanospheres into a hexagonal lattice, and these features render the interface promising soft scaffolds to self-assemble anionic nanomaterials two-dimensionally.     

Temperature-programmed precise control over the sizes of carbon nanospheres based on benzoxazine chemistry

On the basis of benzoxazine chemistry, we have established a new way to synthesize highly uniform carbon nanospheres with precisely tailored sizes and high monodispersity. Using monomers including resorcinol, formaldehyde, and 1,6-diaminohexane, and in the presence of Pluronic F127 surfactant, polymer nanospheres are first synthesized under precisely programmed reaction temperatures. Subsequently, they are pseudomorphically and uniformly converted to carbon nanospheres in high yield, due to the excellent thermal stability of such polybenzoxazine-based polymers. The correlation between the initial reaction temperature (IRT) and the nanosphere size fits well with the quadratic function model, which can in turn predict the nanosphere size at a set IRT. The nanosphere sizes can easily go down to 200 nm while retaining excellent monodispersity, i.e., polydispersity <5%. The particle size uniformity is evidenced by the formation of large areas of periodic assembly structure. NMR, FT-IR, and elemental analyses prove the formation of a polybenzoxazine framework. As a demonstration of their versatility, nanocatalysts composed of highly dispersed Pd nanoparticles in the carbon nanospheres are fabricated, which show high conversion and selectivity, great reusability, and regeneration ability, as evidenced in a selective oxidation of benzyl alcohol to benzaldehyde under moderate conditions.     

A novel amperometric biosensor based on NiO hollow nanospheres for biosensing glucose

NiO hollow nanospheres were synthesized by controlled precipitation of metal ions with urea using carbon microspheres as templates, which were for the first time adopted to construct a novel amperometric glucose biosensor. Glucose oxidase was immobilized on the surface of hollow nanospheres through chitosan-assisted cross-linking technique. Due to the high specific active sites and high electrocatalytic activity of NiO hollow nanospheres, the constructed glucose biosensors exhibited a high sensitivity of 3.43 μA/mM. The low detection limit was estimated to be 47 μM (S/N = 3), and the Michaelis-Menten constant was found to be 7.76 mM, indicating the high affinity of enzyme on NiO hollow nanospheres to glucose. These results show that the NiO hollow nanospheres are a promising material to construct enzyme biosensors.     

Enhancement of the anthracene aqueous solubility by a synergistic effect of alcohols and β-cyclodextrin

The results presented in this paper show that the solubility of anthracene in water increases significantly when β-cyclodextrin and alkanols with carbon numbers from 1 to 4 are added to the solution. The concentrations of the anthracene chosen as a model hydrophobic pollutant were determined using UV–vis spectroscopy. It has been demonstrated that the solubility of anthracene in a 1.1 wt% β-cyclodextrin solution increases by the factor of 45 or 62 when 4 wt% of methanol or ethanol are added, respectively. Obviously, the increase of anthracene solubility is due both to the solvent effect of the alcohols and to the formation of anthracene–β-cyclodextrin (β-CD) “guest–host” complexes. We propose, to use the solubility enhancement based on the β-cyclodextrin/alcohol effect for improving the availability of hydrocarbon pollutants in the biodegradation processes.     

Synthesis and magnetic properties of hollow α-Fe2O3 nanospheres templated by carbon nanospheres

Hollow α-Fe₂O₃ nanospheres were synthesized by using novel carbon spheres as templates. By carefully controlling the fundamental experimental parameters, porous nanospheres with diameters of 60–80 nm and nanojujubes with diameters of 80–100 nm have been efficiently obtained, respectively. The growth mechanism and magnetic properties are also discussed in detail. The coercivity values of the hollow α-Fe₂O₃ nanospheres and nanojujubes are much higher than those of other α-Fe₂O₃ nanomaterials. Due to the unique morphology with cavum and porous wall, the ferromagnetic nanospheres could be promising candidates as a magnetic carrier for drug targeting.     

Adsorption of anthracene using activated carbon and Posidonia oceanica

The aim of this work was to examine the static capacity of adsorption of anthracene by Posidonia oceanica and activated carbon. The effect of experimental parameters pH and contact time on the anthracene adsorption onto cited materials was investigated in detail. The results showed that the anthracene removal on both P. oceanica and activated carbon was unaffected in the pH range of 2–12. The equilibrium data fit well to the Langmuir model with a maximum adsorption capacity of 8.35 mg/g and 0.14 mg/g, respectively with activated carbon and P. oceanica.     

Double function of tris(hydroxymethyl)aminomethane (THAM) for the preparation of colloidal silica nanospheres and the conversion to ordered mesoporous carbon

Tris(hydroxymethyl)aminomethane (THAM) has been found to be an excellent catalyst for the preparation of colloidal silica nanospheres around 10 to 20 nm in size, and THAM on the surfaces of nanospheres is an efficient carbon source for the synthesis of highly ordered mesoporous carbon with controlled pore size by using closely packed nanospheres as a porogen.