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Co Nanoparticles (co + nanoparticle)

Distribution by Scientific Domains
Physics and Astronomy40%

Selected Abstracts

Orientation Ordering of Nanoparticle Ag/Co Cores Controlled by Electric and Magnetic Fields

CHEMPHYSCHEM, Issue 7 2008
Katarína Gmucová Dr.
Abstract The effect of electric and magnetic fields on the sandwich structure Pt/hydrogenated amorphous silicon (a-Si:H)/stearic acid monolayer/Langmuir,Blodgett film of Ag/Co nanoparticles encapsulated in an organic envelope is studied. This structure is used as a working electrode in an electrochemical cell filled with NaCl solution (1 mM) and equipped with an Ag/AgCl reference electrode. Reversible changes in voltammograms are observed due to treatments (negative or positive bias voltage and simultaneous laser irradiation) applied to the designed structure before measurements. As an explanation of the observed phenomena we suggest that both the Co-up and Ag-up (on the a-Si:H surface) orientation orderings of nanoparticle Ag/Co cores are repeatedly reached. The role of the photovoltaic material (a-Si:H) in the observed behavior is explained. Voltammetric measurements with an applied magnetic field support our idea about the orientation ordering of nanoparticle cores. [source]

Electrocatalysts: Facile Construction of Pt,Co/CNx Nanotube Electrocatalysts and Their Application to the Oxygen Reduction Reaction (Adv. Mater.

ADVANCED MATERIALS, Issue 48 2009
48/2009)
Pt,Co alloyed nanoparticles can be facilely immobilized onto CNx nanotubes due to the incorporated nitrogen, report Yanwen Ma, Zheng Hu, and co-workers on p. 4953. The as-prepared electrocatalysts exhibit good performance for oxygen reduction reactions in acidic media arising from the high dispersion and alloying effect of Pt,Co nanoparticles, as well as the intrinsic catalytic capacity of CNx nanotubes, which is significant for the development of fuel cells. [source]

Facile Construction of Pt,Co/CNx Nanotube Electrocatalysts and Their Application to the Oxygen Reduction Reaction

ADVANCED MATERIALS, Issue 48 2009
Shujuan Jiang
A straight forward method for immobilizing Pt,Co alloyed nanoparticles onto nitrogen-doped CNx nanotubes is presented (see image). The as-prepared electrocatalysts exhibit good performance for oxygen reduction reaction in acidic medium arising from the high-dispersion and alloying effect of the Pt,Co nanoparticles and the intrinsic catalytic capacity of the CNx nanotubes. [source]

Electrochemical synthesis and stabilization of cobalt nanoparticles

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2006
A. Ledo-Suárez
Abstract Cobalt nanoparticles (NPs) were synthesized via an electrochemical method in the presence of tetraalkylammonium salt. The nanometer dimensions of the NPs can be controlled in a simple way by adjustment of the current density. From these particles stable colloidal suspensions are prepared in the presence of a fatty acid (oleic acid) and triphenylphosphine. The colloidal system is stable against oxidation when they are kept in heptane (C7H16). Transmission electron microscopy (TEM) was employed to determine the core size and the shape of metal nanoparticles. The chemical interaction of the surfactant with the Co nanoparticles was studied by using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). Thermogravimetric analysis (TGA) was used to study the thermal stability and the composition of the capped cobalt nanoparticles. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Influence of substrate and temperature on the shape of deposited Fe, Co, and FeCo nanoparticles

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2010
Wolfgang Rosellen
Abstract In situ scanning tunneling measurements have been carried out on mass-filtered supported Fe, Co, and FeCo alloy nanoparticles with diameters between 4 and 14,nm. These nanoparticles are prepared from the gas phase using a continuously working cluster source and are subsequently deposited on bare W(110) and Ni(111)/W(110) surfaces. The size and the crystallographic structure before deposition are determined by high resolution transmission electron microscopy (HRTEM), the height of the nanoparticles on the substrate by scanning tunneling microscopy (STM). Depending on the substrate the particles do not maintain their spherical shape after deposition. The melting at elevated temperatures results in an anisotropic elongation along the [001] direction of the W(110) substrate. STM illustration of large Co nanoparticles deposited on an atomically flat W(110)-surface. [source]