Borohydride reductions of metal ions. A new understanding of the chemistry leading to nanoscale particles of metals, borides, and metal borates

Glavee, George N.; Klabunde, Kenneth J.; Sorensen, Christopher M.; Hadjapanayis, George C.

doi:10.1021/la00039a008

“…Since that time, quite a number of studies have dealt with structural and magnetic properties of Co-B composite particles prepared by this technique. The effects of reaction conditions on nanosized particles in the borohydride reduction process were studied systematically by Glavee et al [13,14]. According to their studies, the primary product of this reaction, when carried out in aqueous medium, are either nanosized Co 2 B or Co(BO 2 ) 2 particles depending on the specific mixing procedures and product handling.…”

Section: Introductionmentioning

confidence: 99%

Nanocomposites of magnetic cobalt nanoparticles and cellulose

Pirkkalainen

¹

,

Leppänen

²

,

Vainio

³

et al. 2008

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Abstract. Polymeric matrices with stabilized metallic nanoparticles constitute an important class of nanostructured materials, because polymer technology allows fabrication of components with various electronic, magnetic and mechanical properties. The porous cellulose matrix has been shown to be a useful support material for platinum, palladium, silver, copper and nickel nanoparticles. In the present study, nanosized cobalt particles with enhanced magnetic properties were made by chemical reduction within a microcrystalline cellulose (MCC) matrix. Two different chemical reducers, NaBH4 and NaH2PO2, were used, and the so-formed nanoparticles were characterized with X-ray absorption spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. These experimental techniques were used to gain insight into the effect of different synthesis routes on structural properties of the nanoparticles. Magnetic properties of the nanoparticles were studied using a vibrating sample magnetometer. Particles made via the NaBH4 reduction were amorphous Co-B or Co oxide composites with diminished ferromagnetic behaviour and particles made via the NaH2PO2 reduction were well-ordered ferromagnetic hcp cobalt nanocrystals.

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“…These results suggest that borate product from decomposition of borohydride residues reacts with metallic cobalt and oxygen to give cobalt borates. Other possibility that cannot be discarded is the simultaneous formation of metallic cobalt and cobalt borides composites as have been reported by Glavee et al [8,9], in this case a two step oxidation process is also expected. Additionally, it is noted that organic phase content is higher for vesicles sample and the IR spectrum corroborates the presence of oleic acid (see Fig.…”

Section: Thermogravimetric Profilesmentioning

confidence: 81%

“…Therefore, in the present work the oxidation thermal profiles of metallic cobalt nano and micro particles obtained in colloidal dispersion is explored. The micro and nano particles under study were obtained using classical methods such as the reduction in aqueous media [8,9] and the so-called polyol method [10][11][12][13]. Results show that strong reducing agent such as borohydride contaminates the products not necessarily forming borides, as has been reported previously [8,9].…”

Section: Introductionmentioning

confidence: 89%

“…The micro and nano particles under study were obtained using classical methods such as the reduction in aqueous media [8,9] and the so-called polyol method [10][11][12][13]. Results show that strong reducing agent such as borohydride contaminates the products not necessarily forming borides, as has been reported previously [8,9]. It was found that when CTAB is used as template the system forms homogeneous microstructures distributions of secondary hollow particles with spherical morphology that organize in elongated mesoscopic systems.…”

Section: Introductionmentioning

confidence: 90%

“…The solution color changes from pale pink into black after approximately 10 min. Eventually, the proper amount of diethyl ether (8 ml) was then added under non-anaerobic conditions in order to minimize the formation of boron-cobalt compounds [8,9].…”

Section: Borohydride Reduction In Aqueous Mediamentioning

confidence: 99%

See 2 more Smart Citations

Synthesis and Thermal Behavior of Metallic Cobalt Micro and Nanostructures

Gattorno

¹

,

González²,

Santiago-Jacinto³

et al. 2011

Nano-Micro Lett

0

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Abstract:In this contribution, a comparative study of metallic cobalt micro and nanoparticles obtained in solution by four different chemical routes is reported. Classic routes such as borohydride reduction in aqueous media and the so-called polyol methodology were used to obtain the cobalt nanostructures to be studied. Using CTAB as surfactant, cobalt hollow nanostructures were obtained. The use of strong reducing agents, like sodium borohydride, favors the formation of quasi-monodispersed nanoparticles of about 2 nm size but accompanied with impurities; for hydrazine (a mild reducer), nanoparticles of larger size are obtained which organize in spherical microagglomerates. Valuable information on the particles thermal stability and on nature of the species anchored at their surface was obtained from thermogravimetric curves. The samples to be studied were characterized from UV-vis, IR, X-ray diffraction, and electron microscopy images (scanning and transmission).

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Cobalt Nanomaterials: Synthesis and Characterization

Zhang

¹

,

Zhou

²

,

Lu³

et al. 2009

Nanotechnologies for the Life Sciences

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The sections in this article are Introduction The Characterization of Co Nanoparticles Shape, Size, and Microstructure Transmission Electron Microscopy Scanning Electron Microscopy Magnetic Properties Morphology Elemental and Chemical Analysis Auger Electron Spectroscopy X ‐Ray Photoelectron Spectroscopy ( XPS ) Fourier Transform Infrared ( FTIR ) Spectroscopy The Crystal Structure: X ‐Ray Diffraction ( XRD ) Synthesis of Cobalt‐Based Nanoparticles Introduction Stabilization of Nanomaterials Synthesis of Cobalt Nanomaterials Physical Methods Chemical Vapor Deposition Liquid‐Phase Chemical Precipitation Summary and Outlook Magnetic Properties of Co Nanoparticles Introduction Finite Size Effects Size‐Dependent Crystalline Structure Size‐Dependent Magnetic Domain Structure and the Reversal of Co Nanoparticles Thermal‐Activation Effect on the Moment and Coercivity Superparamagnetism in Co Nanoparticle System and its Direct Investigation Surface Effects of Co Nanoparticles Moment Enhancement of Surface Atoms Anisotropy Enhancement of Co Nanoparticles Exchange Bias Between the Core and the Oxidized Surface in Co Nanoparticles Summary Summary and Outlook

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Borohydride reductions of metal ions. A new understanding of the chemistry leading to nanoscale particles of metals, borides, and metal borates

Cited by 185 publications

References 0 publications

Nanocomposites of magnetic cobalt nanoparticles and cellulose

Nanocomposites of magnetic cobalt nanoparticles and cellulose

Synthesis and Thermal Behavior of Metallic Cobalt Micro and Nanostructures

Cobalt Nanomaterials: Synthesis and Characterization

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