Synthesis and characterization of sulfonated-mercaptopropanoic acid coated Fe3O4 nanoparticles as a novel acid magnetic catalyst for Biginelli reaction

In this paper, Fe₃O₄ nanoparticles were coated with 3-mercaptopropanoic acid (MPA) through a simple in-situ method and subsequently oxidized by H₂O₂/H₂SO₄ to obtain a novel acid magnetic catalyst (Fe₃O₄/SMPA). This catalyst exhibited high catalytic activity in the one-pot synthesis of different 3,4-dihydropyrimidin-2(1H)-ones under mild and solvent-free conditions, along with excellent level of reusability.     

Synthesis of polygonized carbon nanotubes utilizing inhomogeneous catalyst activity of nonspherical Fe3O4 nanoparticles

The synthesis of novel carbon nanotubes (CNTs) with polygonal cross sections by heating a powder mixture of ferrocene, oxalic acid, and the alkali metal potassium at mediate temperatures (480-500 degrees C) is reported. This kind of special polygonized CNTs has two distinctive characters: first, ribbonlike polygonized CNTs have diameters between 60 and 200 nm, and the lengths as long as several microns; second, the edge of polygonized CNTs is well-graphitized, the wall of which is amorphous. On the basis of evidence that the formation of polygonized CNTs appears to be strongly determined by inhomogeneous catalytic activity of nonspherical Fe(3)O(4) nanoparticles, we propose the possible growth model.     

Synthesis of cyclo‐olefin copolymer latexes and their carbon nanotube composite nanoparticles

An efficient and environmentally benign synthetic method for the production of the stabilized cyclo‐olefin copolymer latexes and their carbon nanotube composite nanoparticles has been developed using an emulsion ring opening metathesis copolymerization catalyzed by the 2nd generation Grubbs catalyst in aqueous solution. Homopolymerizations of norbornene (NB) and dicyclopentadiene (DCPD) in aqueous solution yield unstable polymer latexes in combination with a large amount of their flocculation fractions. Copolymerizations of NB or DCPD with a selected liquid cyclo‐olefin comonomer dramatically improve not only the colloidal stability of the copolymer latexes but also the thermal stability of the copolymer nanoparticles. The liquid cyclo‐olefin comonomer plays a double role as a liquefied agent for the solid NB and DCPD monomers before the emulsification treatment, and a reactive comonomer itself to control entirely the copolymerization system. The as‐prepared cyclo‐olefin copolymer latexes exhibit an exceptionally high compatibility with a well‐dispersed carbon nanotube (CNT) in aqueous solution due to strong π–π interactions between the graphitic surfaces of the CNT with the C‐C double bonds located on the cyclo‐olefin copolymer main chains. Accordingly, a binary blending of these two well‐dispersed colloidal systems in aqueous solution led to the fabrication, for the first time, of the highly electrical conductive cyclo‐olefin copolymer/CNT composite nanoparticles. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4584–4591     

Iron/multiwalled carbon nanotube (Fe/MWCNT) hybrid materials characterization: thermogravimetric analysis as a powerful characterization technique

Journal of Thermal Analysis and Calorimetry - Nanomaterials and nanocomposites have gained relevance in science and technology due to their excellent properties. Therefore, the characterization of...     

Design,preparation and characterization of Cu/GA/Fe3O4@SiO2 nanoparticles as a catalyst for the synthesis of benzodiazepines and imidazoles

The synthesis and characterization of an efficient and reusable nanocatalyst, Cu/GA/Fe₃O₄@SiO₂, obtained by ultrasonic‐assisted grafting of guanidineacetic acid on modified Fe₃O₄@SiO₂ core–shell nanocomposite spheres and subsequent immobilization of Cu(II), are described. The catalyst was characterized by means of X‐ray diffraction, scanning and transmission electron microscopies, energy‐dispersive X‐ray spectroscopy, elemental analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy, vibrating sample magnetometry and inductively coupled plasma optical emission spectrometry. The prepared nanocatalyst facilitated an efficient and straightforward friendly procedure for the synthesis of benzodiazepines and imidazoles in ethanol and under solvent‐free conditions, respectively. The nanocatalyst can be easily recovered using a magnet and reused several times without any significant loss of activity. Copyright © 2016 John Wiley & Sons, Ltd.     

Stable confinement of Fe/Fe_3C in Fe,N-codoped carbon nanotube towards robust zinc-air batteries

Catalytic oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) have garnered great attention as the key character in metal-air batteries.Herein,we developed a superior nonprecious bifunctional oxygen electrocatalyst,fabricated through spatial confinement of Fe/Fe_3 C nanocrystals in pyridinic N and Fe-Nx rich carbon nanotubes(Fe/Fe_3 C-N-CNTs).During ORR,the resultant electrocatalyst exhibits positive onset pote ntial of 1.0 V(vs.RHE),large half-wave potentials of 0.88 V(vs.RHE),which is more positive than Pt/C(0.98 V and 0.83 V,respectively).Remarkably,Fe/Fe_3 C-N-CNTs exhibits outstanding durability and great methanol tolerance,exceeding Pt/C and most reported nonprecious metal-based oxygen reduction electrocatalysts.Moreover,Fe/Fe_3 C-N-CNTs show a markedly low potential at j=10 mA/cm~2,small Tafel slopes and extremely high stability for OER.Impressively,the Fe/Fe_3 C-N-CNTs-based Zn-air batteries demonstrate high power density of 183 mW/cm~2 and robust charge/discharge stability.It is revealed that the spatial confinement effect can impede the aggregation and corrosion of Fe/Fe_3 C nanocrystals.Meanwhile,Fe/Fe_3 C and Fe-Nx play synergistic effect on boosting the ORR/OER activity,which provides an important guideline for construction of inexpensive nonprecious metal-carbon hybrid nanomaterials.     

Synthesis of vertically aligned carbon nanotube arrays on polyhedral Fe/Al2O3 catalysts

Polyhedral Fe/Al(2)O(3) catalysts prepared by an impregnation method were used for the synthesis of vertically aligned carbon nanotube (CNT) arrays from the pyrolysis of ethylene at 800 °C.     

3-D carbon nanotube structures used as high performance catalyst for oxygen reduction reaction

We report a high performance oxygen reduction reaction (ORR) catalyst based on vertically aligned, nitrogen-doped carbon nanotube (VA-NCNT) arrays. Characterization in conditions analogous to the operation of a polymer electrolyte membrane fuel cell show ORR taking place on the catalyst at a favorable reduction potential with a superior current density and greater rate constant.     

Fibroin-functionalized magnetic carbon nanotube as a green support for anchoring silver nanoparticles as a biocatalyst for A3 coupling reaction

Novel and powerful fibroin-functionalized magnetic carbon nanotube–supported silver nanoparticles (CNT–Fe₃O₄–fibroin–Ag) were successfully synthesized as a nontoxic and inexpensive biocatalyst. The structure of the organic–inorganic hybrid bionanocomposite was characterized by various techniques such as Fourier transform infrared spectroscopy, thermogravimetric analysis, energy-dispersive X-ray, field emission-scanning electron microscopy, transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry, atomic absorption spectroscopy, and inductively coupled plasma-optical emission spectrometry. Then, the catalytic activity of synthesized bionanocomposite was evaluated in the three-component A³ coupling reaction under solvent-free conditions with good to excellent yields. Several propargylamine derivatives were synthesized by the reaction of different aldehydes with amines and phenylacetylene. Biodegradability, biocompatibility, availability, easy synthesis, high stability, high-throughput, cost-effectiveness, and efficient magnetic separation are some advantages of this catalyst that make it economically justified and sustainable. Moreover, the catalyst can be recycled for several runs without appreciable loss in its catalytic activity.     

Synthesis of polyaniline/multiwall carbon nanotube composite via inverse emulsion polymerization

The composite of polyaniline (PANI) and multiwall carbon nanotube carboxylated through acid treatment (c‐MWCNT) was synthesized by chemical oxidative polymerization in an inverse emulsion system. The resultant composites were compared with products from aqueous emulsion polymerization to observe the improvements in electrical conductivity, structural properties, and thermal stability obtained by this synthetic method. Prior to the inverse emulsion polymerization, MWCNT was treated with a strong acid mixture to be functionalized with carboxylic acid groups. Carboxylic acid groups on surfaces induced selective dispersibility between polar and nonpolar solvents because of the increase of hydrophilicity. As the content of c‐MWCNT was increased, the electrical conductivity was increased by a charge transport function from the intrinsic electrical conductivity of MWCNT and the formation of a highly ordered dense structure of PANI molecules on the surface of c‐MWCNT. The images observed with electron spectroscopy showed the capping of c‐MWCNT with PANI. The growth of additional ordered structures of PANI/c‐MWCNT composite, which was observed through wide‐angle X‐ray diffraction patterns, supported the capping by PANI. It was observed that the doping of the composite had a significant relationship with the concentration of dodecylbenzenesulfonic acid (DBSA). The thermal stability of PANI composite was improved by the addition of c‐MWCNT; this was thought to be related with structure ordering by inverse emulsion polymerization. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2255–2266, 2008     

Highly efficient Fe/N/C catalyst using adenosine as C/N-source for APEFC

An environmentally friendly precursor, adenosine, has been used as a dual source of C and N to synthesize nitrogen-doped carbon catalyst with/without Fe. A hydrothermal carbonization method has been used and water is the carbonization media. The morphology of samples with/without Fe component has been compared by HRTEM, and the result shows that Fe can promote the graphitization of carbon. Further electro-chemical test shows that the oxygen reduction reaction(ORR) catalytic activity of Fe-containing sample(C–Fe N) is much higher than that of the Fe-free sample(C–N). Additionally, the intermediates of C–Fe N formed during each synthetic procedure have been thoroughly characterized by multiple methods,and the function of each procedure has been discussed. The C–Fe N sample exhibits high electro-catalytic stability and superior electro-catalytic activity toward ORR in alkaline media, with its half-wave potential 20 mV lower than that of commercial Pt/C(40 wt%). It is further incorporated into alkaline polymer electrolyte fuel cell(APEFC) as the cathode material and led to a power density of 100 m W/cm~2.     

In situ synthesis and characterization of multiwalled carbon nanotube/Au nanoparticle composite materials

An effective and facile in situ reduction approach for the fabrication of carbon nanotube-supported Au nanoparticle (CNT/Au NP) composite nanomaterials is demonstrated in this article. Linear polyethyleneimine (PEI) is ingeniously used as both a functionalizing agent for the multiwalled carbon nanotubes (MWNTs) and a reducing agent for the formation of Au NPs. This method involves a simple mixing process followed by a mild heating process. This approach does not need the exhaustive surface oxidation process of CNTs. The coverage of Au NPs on CNTs is tunable by varying the experimental parameters, such as the initial molar ratio of PEI to HAuCl4, the relative concentration of PEI and HAuCl4 to MWNTs, and the temperature and duration of the heat treatment. More importantly, even the heterogeneous CNT/Au composite nanowires are obtainable through this method. TEM, XPS, and XRD are all used to characterize the CNT/Au composite materials. In addition, the optical and electrocatalytic properties are investigated.     

Cerium vanadate/carbon nanotube hybrid composite nanostructures as a high-performance anode material for lithium-ion batteries

The pristine CeVO4 and CeVO4/CNT hybrid composite nanostructured samples were facilely synthesized using a simple silicone oil-bath method.From the X-ray diffra...     

Immobilized VOsalpr on modified Fe3O4 nanoparticles as a magnetically separable epoxidation catalyst

Fe₃O₄ nanoparticles were prepared and modified with chloropropyl trimethoxysilane (Cl-PTMS). The N,N′-bis(3-salicylidenaminopropyl)amine (salpr) Schiff base ligand was then immobilized on modified Fe₃O₄, which was followed by the addition of VOSO₄ in order to complex it with immobilized sa0lpr. The obtained nanocatalyst designated as VO(Salpr)/SCMNPs was characterized by FT–IR, XRD, SEM, TEM, and VSM techniques. It was found that VO(salpr)/SCMNPs successfully catalyze the epoxidation of allyl alcohols, such as limonene, 1-octene-3-ol, trans-2-hexene-1-ol and geraniol with 50 to 100% conversion and 62 to 100% selectivity with tert-butylhydroperoxide (TBHP). The study of this catalyst's stability and reusability revealed that VO(salpr)/SCMNPs behaves heterogeneously with no desorption during the course of the epoxidation reactions.     

84% catalyst activity of water-assisted growth of single walled carbon nanotube forest characterization by a statistical and macroscopic approach

We propose a statistical and macroscopic analysis to estimate the catalyst activity of water-assisted growth (super-growth) of single-walled nanotubes (SWNT) and to characterize SWNT forests. The catalyst activity was estimated to be 84% (+/-6%), the highest ever reported. The SWNT forest was found to be a very sparse material where SWNTs represent only 3.6% of the total volume. This structural sparseness is believed to play a critical role in achieving highly efficient growth.     

基于N-掺杂碳包覆Fe3N复合材料的高效异相电芬顿降解有机物

水污染导致的缺水危机、水质恶化和生态环境破坏等问题,严重影响人的健康及社会的和谐可持续发展.异相电芬顿技术因催化剂可循环利用、宽pH适用范围等优点而广受关注.常见的催化剂以铁、铁氧化物等铁基材料为主,存在金属颗粒分布不均匀、铁元素易溶出、铁循环易受阻和H2O2选择性和转化效率低等问题,严重制约该技术的发展.尽管可以通过...