A Study of Nanosize Fe3O4 Deposited on Carbon Matrix

2008 ◽  
Vol 8 (2) ◽  
pp. 591-594 ◽  
Author(s):  
B. Banov ◽  
L. Ljutzkanov ◽  
I. Dimitrov ◽  
A. Trifonova ◽  
H. Vasilchina ◽  
...  
Keyword(s):  
Average Particle Size ◽  
Carbon Matrix ◽  
Reversible Capacity ◽  
Carbon Support ◽  
Test Sample ◽  
Constant Current ◽  
Average Particle ◽  
Scanning Electron Micrographs ◽  
Lithium Secondary Batteries ◽  
Electrochemical Tests

Nanosized crystalline Fe3O4 (with an average particle size of 16 nm) was successfully synthesized on a carbon matrix surface. The prepared sample was heat-treated in the temperature range 300 °C–750 °C to remove residual impurities and to obtain a final product with a 77:23 ratio between magnetite and the carbon support. The sample was subjected to physicochemical and electrochemical tests. The purity of the phase and the particles size was determined by X-ray diffraction analysis and confirmed by field emission scanning electron micrographs. The specific surface area of the sample measured by the B.E.T method was 120 m2 g−1. A series of electrochemical tests including EIS, CV and long-term constant current cycling have been performed. The obtained reversible capacity within 15 cycles was in the range 400–550 mA h · g−1. The electrochemical behavior of the test sample and its possible practical use as an anode material in lithium secondary batteries are discussed.

scholarly journals Preparation and Electrocatalytic Characteristics Research of Pd/C Catalyst for Direct Ethanol Fuel Cell

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Qiao Xia Li ◽  
Ming Shuang Liu ◽  
Qun Jie Xu ◽  
Hong Min Mao
Keyword(s):  
Fuel Cell ◽  
Average Particle Size ◽  
Active Surface ◽  
Carbon Support ◽  
Catalytic Performance ◽  
Active Surface Area ◽  
Average Particle ◽  
Ethanol Fuel ◽  
Direct Ethanol Fuel Cell ◽  
Electrochemical Active Surface Area

Two kinds of carbon-support 20% Pd/C catalysts for use in direct ethanol fuel cell (DEFC) have been prepared by an impregnation reduction method using NaBH4and NaH2PO2as reductants, respectively, in this study. The catalysts were characterized by XRD and TEM. The results show that the catalysts had been completely reduced, and the catalysts are spherical and homogeneously dispersed on carbon. The electrocatalytic activity of the catalysts was investigated by electrochemical measurements. The results indicate that the catalysts had an average particle size of 3.3 nm and showed the better catalytic performance, when NaBH4was used as the reducing agent. The electrochemical active surface area of Pd/C (NaBH4) was 56.4 m2·g−1. The electrochemical activity of the Pd/C (NaBH4) was much higher than that of Pd/C (NaH2PO2).

scholarly journals Commercial Cokes and Graphites as Anode Materials for Lithium - Ion Cells

1997 ◽  
Vol 496 ◽  
Author(s):  
David J. Derwin ◽  
Kim Kinoshita ◽  
Tri D. Tran ◽  
Peter Zaleski
Keyword(s):  
Electron Microscopy ◽  
Ethylene Carbonate ◽  
Average Particle Size ◽  
Chemical Properties ◽  
Lithium Ion ◽  
Reversible Capacity ◽  
Bet Surface Area ◽  
Average Particle ◽  
Electrochemical Characteristics ◽  
Wide Range

AbstractSeveral types of carbonaceous materials from Superior Graphite Co. were investigated for lithium ion intercalation. These commercially available cokes, graphitized cokes and graphites have a wide range of physical and chemical properties. The coke materials were investigated in propylene carbonate based electrolytes and the graphitic materials were studied in ethylene carbonate / dimethyl solutions to prevent exfoliation. The reversible capacities of disordered cokes are below 230 mAh / g and those for many highly ordered synthetic (artificial) and natural graphites approached 372 mAh / g (LiC6). The irreversible capacity losses vary between 15 to as much as 200 % of reversible capacities for various types of carbon. Heat treated cokes with the average particle size of 10 microns showed marked improvements in reversible capacity for lithium intercalation. The electrochemical characteristics are correlated with data obtained from scanning electron microscopy (SEM), high resolution transmission electron microscopy (TAM), X - ray diffraction (XRD) and BET surface area analysis. The electrochemical performance, availability, cost and manufacturability of these commercial carbons will be discussed.

Preparation of fine-grained MgO and Gd2O3 stabilized ZrO2 thin films by electron beam physical vapor deposition co-evaporation

1997 ◽  
Vol 12 (12) ◽  
pp. 3260-3265 ◽  
Author(s):  
F. Tcheliebou ◽  
M. Boulouz ◽  
A. Boyer
Keyword(s):  
Thin Films ◽  
Electron Beam ◽  
Average Particle Size ◽  
Electron Gun ◽  
Cubic Phase ◽  
Crystallographic Structure ◽  
Average Particle ◽  
Scanning Electron Micrographs ◽  
Dopant Content ◽  
Fine Grained

Thin films of ZrO2 doped with MgO and Gd2O3, 1–1.5 μm in thickness are formed onto nickel substrates by reactive thermal evaporation using a dual-hearth electron gun. X-ray diffraction patterns of the deposits show changes in the crystallographic structure and average particle size as a function of the dopant content. A mixture of monoclinic and tetragonal phases gradually disappears to become a single cubic phase with increasing dopant molar fraction. The average crystallite size deduced from diffraction line broadening decreases as the dopant content increases. This observation is strongly confirmed by scanning electron micrographs which reveal a smooth surface topography. Fine-grained materials obtained here are interpreted in terms of high nucleation rate and kinetically limited grain growth. It appears that composition, crystallographic structure, and microstructure relations are of paramount importance in ZrO2-based films prepared by electron-beam evaporation.

scholarly journals Easy preparation of SnO2@carbon composite nanofibers with improved lithium ion storage properties

2010 ◽  
Vol 25 (8) ◽  
pp. 1516-1524 ◽  
Author(s):  
Zunxian Yang ◽  
Guodong Du ◽  
Zaiping Guo ◽  
Xuebin Yu ◽  
Zhixin Chen ◽  
...  
Keyword(s):  
Anode Material ◽  
Carbon Nanofibers ◽  
Lithium Ion ◽  
Carbon Matrix ◽  
Reversible Capacity ◽  
Carbon Composite ◽  
Constant Current ◽  
Thermal Treatments ◽  
Ion Storage ◽  
Potential Use

SnO2@carbon nanofibers were synthesized by a combination of electrospinning and subsequent thermal treatments in air and then in argon to demonstrate their potential use as an anode material in lithium ion battery applications. The as-prepared SnO2@carbon nanofibers consist of SnO2 nanoparticles/nanocrystals encapsulated in a carbon matrix and contain many mesopores. Because of the charge pathways, both for the electrons and the lithium ions, and the buffering function provided by both the carbon encapsulating the SnO2 nanoparticles and the mesopores, which tends to alleviate the volumetric effects during the charge/discharge cycles, the nanofibers display a greatly improved reversible capacity of 420 mAh/g after 100 cycles at a constant current of 100 mA/g, and a sharply enhanced reversible capacity at higher rates (0.5, 1, and 2 C) compared with pure SnO2 nanofibers, which makes it a promising anode material for lithium ion batteries.

Study on Nickel Nanopowders Prepared by Arc Plasma

2013 ◽  
Vol 734-737 ◽  
pp. 1555-1558
Author(s):  
Cong Hua Hou ◽  
Yun Ge Chen
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Barometric Pressure ◽  
Constant Current ◽  
Average Particle ◽  
Face Centered Cubic ◽  
Arc Plasma ◽  
X Ray Diffraction ◽  
Current Voltage ◽  
Face Centered

In order to prepare the nickel nano-metal with high purity and uniform particle size , the arc plasma method was used. The nano-Ni was got under a constant current , voltage , barometric pressure, hydrogen and argon gas . The nickel nanopowders were tested through the Scan Electron Microscope (SEM ), X-ray diffraction (XRD), Laser Sizer Analysis (LSA). The results indicated that the feature of the nickel nanopowders were mainly spherical, smooth surface. The nickel powder particle distribute from 40 to 80nm. And average particle size is 60nm. Nanocrystals had a better internal crystallinity. The crystal structure is face-centered cubic FCC structure, the same as ordinary nickel nanoparticles .

The Effect of Activation Time of Phosphoric Ester Cellulose Particles on the Electrorheological Properties of Anhydrous ER Fluids

2001 ◽  
Vol 15 (06n07) ◽  
pp. 1009-1016 ◽  
Author(s):  
B. G. Ahn ◽  
U. S. Choi ◽  
C. H. Kim ◽  
O. K. Kwon
Keyword(s):  
Particle Size ◽  
Electric Fields ◽  
Silicone Oil ◽  
Average Particle Size ◽  
Constant Current ◽  
Average Particle ◽  
Activation Time ◽  
Constant Current Density ◽  
Phosphoric Ester ◽  
Er Fluids

The electrorheological (ER) behavior of suspensions in silicone oil of phosphoric ester cellulose powder (average particle size: 17.77 μm) was investigated at room temperature with electric fields up to 2.5 kV/mm. For development of anhydrous ER fluids using at wide temperature range, it was sought the effect of activation time of phosphoric ester cellulose particles on the ER activities. Anhydrous ER fluids based on the phosphoric ester cellulose particles made from cellulose particles treating in chemical solution of 2M phosphoric acid and 4M urea and heating at 150°C were measured. After activating the phosphoric ester cellulose anhydrous ER fluids at 120°C, not only analysis of dispersing cellulose particles but also electroroheological characteristics of ER fluids such as dielectric constant, current density, electrical conductivity and rheological properties were studied. Activation time had a large influence to ER properties of anhydrous ER fluids based on phosphoric ester cellulose. As the activation time went by, particle size and number of dispersing particles, electrical properties, dynamic yield stress on electric field, initial apparent viscosity (η0) and electrorheological effect (τA/τ0) of phosphoric ester cellulose ER fluids increased with increasing activation time at 120°C till activation time over 5 hours.

Formation of metal-carbon nanocomposites based on Cu-Fe alloy nanoparticles and carbonized polyacrylonitrile

2021 ◽  
Vol 1 ◽  
pp. 58-66
Author(s):  
A.A. Vasilev ◽  
◽  
E.L. Dzidziguri ◽  
M.N. Efimov ◽  
D.G. Muratov ◽  
...  
Keyword(s):  
Particle Size ◽  
Carbon Nanostructures ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Carbon Matrix ◽  
Synthesis Temperature ◽  
Average Particle ◽  
Synthesis Of Nanoparticles ◽  
Fe Nanoparticles ◽  
Average Size

A method for the synthesis of nanoparticles of the Cu-Fe bimetallic system with limited mutual solubility of the components is proposed. The synthesis method consists of a one-stage process of IR pyrolysis of precursors in the form of films obtained from a joint solution of polyacrylonitrile and hydrates-nitrates of iron and copper. The effect of the synthesis temperature on the structure formation of the nanocomposites and the phase composition of bimetallic Cu-Fe nanoparticles dispersed in the carbon matrix was studied. The analysis showed a simultaneous presence of Fe and Cu phases in nanocomposites, presumably with a low solubility of the components. The average particle size is 14-17 nm and changes insignificantly with an increase in the synthesis temperature from 400 to 700°C. An increase in the synthesis temperature to 800°C led to a broadening of the particle size distribution and the increase in the average size. The formation of complex carbon nanostructures on Cu-Fe nanoparticles is found.

Zn0.5Co0.5O Solid Solution Nanoparticles with Durable Life for Rechargeable Lithium-ion Batteries

Nano LIFE ◽  
2014 ◽  
Vol 04 (04) ◽  
pp. 1441015 ◽  
Author(s):  
Linlin Wang ◽  
Daoli Zhao ◽  
Min Zhang ◽  
Caihua Wang ◽  
Kaibin Tang ◽  
...  
Keyword(s):  
Solid Solution ◽  
Particle Size ◽  
Energy Storage ◽  
Average Particle Size ◽  
Rate Capability ◽  
Lithium Ion ◽  
Reversible Capacity ◽  
Average Particle ◽  
Li Ion Batteries ◽  
Li Ion

Zn 0.5 Co 0.5 O solid solution materials have been extensively studied for possible spintronic applications, however, there are only a few reports using Zn 0.5 Co 0.5 O nanostructures for energy storage. Here, we report the preparation of Zn 0.5 Co 0.5 O nanoparticles with the average particle size 10 nm and their application as anode material for rechargeable Li -ion batteries (LIBs). Electrochemical measurements demonstrate that the Zn 0.5 Co 0.5 O solid solution nanoparticles deliver a stable reversible capacity of 309 mA h g-1 up to 250 cycles at 1 C rate. These results show higher-rate capability and better cycle durability compared with those of the reported ZnO or ZnO -based anodes.

scholarly journals Synthesis and characterization of ternary Pt-alloy nano particles for hydrogen fuel cell application

2020 ◽  
Vol 12 (1) ◽  
pp. 419-425
Author(s):  
Alhassan Kabiru Usman ◽  
Kamal Danazumi
Keyword(s):  
Electron Microscope ◽  
Average Particle Size ◽  
Carbon Support ◽  
Peak Position ◽  
Reduction Reaction ◽  
Nano Particles ◽  
Alloy Formation ◽  
Average Particle ◽  
Hydrogen Fuel Cell ◽  
Tem Analysis

A novel ternary PtM2 nano structures was prepared using simple salvothermal process. The alloy formation has been ascertained using different characterizations techniques such as X-ray diffraction, Tunneling electron microscope TEM, Scanning electron microscope SEM, EDX. The XRD pattern reveals that, the peak position was shifted to higher 2𝜃 angle specifying the presence of Co and Ni into the lattice to form an ordered L10 phase with a reduced Pt-Pt distance. The thickness of the alloy was found to be ~4.3nm and interplaner distance of ~0.23nm which correlate with TEM analysis with an average particle size ~20nm and distribution of the catalyst on carbon support was also investigated by TEM images. SEM was used to obtain the surface morphology of the synthesized catalyst as well the amount of metallic loaded from EDX. Key words; Platinum, Cobalt, Nickel on Carbon Support (PCN/C), Platinum, Cobalt and Nickel for 8 hour (PCN-8h), Commercial Platinum on Carbon Support (Pt/C), Oxidation Reduction Reaction (ORR), PEMFC, SEM, EDX, TEM, XRD.  

Enhanced catalytic activity of low-Pt content nanocatalysts supported on hollow carbon spheres for the ORR in alkaline media

MRS Advances ◽  
2020 ◽  
Vol 5 (57-58) ◽  
pp. 2961-2972
Author(s):  
P.C. Meléndez-González ◽  
E. Garza-Duran ◽  
J.C. Martínez-Loyola ◽  
P. Quintana-Owen ◽  
I.L. Alonso-Lemus ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Anion Exchange ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Alkaline Media ◽  
High Catalytic Activity ◽  
Average Particle ◽  
Carbon Spheres ◽  
Hollow Carbon ◽  
Hollow Carbon Spheres

In this work, low-Pt content nanocatalysts (≈ 5 wt. %) supported on Hollow Carbon Spheres (HCS) were synthesized by two routes: i) colloidal conventional polyol, and ii) surfactant-free Bromide Anion Exchange (BAE). The nanocatalysts were labelled as Pt/HCS-P and Pt/HCS-B for polyol and BAE, respectively. The physicochemical characterization of the nanocatalysts showed that by following both methods, a good control of chemical composition was achieved, obtaining in addition well dispersed nanoparticles of less than 3 nm TEM average particle size (d) on the HCS. Pt/HCS-B contained more Pt0 species than Pt/HCS-P, an effect of the synthesis method. In addition, the structure of the HCS remains more ordered after BAE synthesis, compared to polyol. Regarding the catalytic activity for the Oxygen Reduction Reaction (ORR) in 0.5 M KOH, Pt/HCS-P and Pt/HCS-B showed a similar performance in terms of current density (j) at 0.9 V vs. RHE than the benchmark commercial 20 wt. % Pt/C. However, Pt/HCS-P and Pt/HCS-B demonstrated a 6 and 5-fold increase in mass catalytic activity compared to Pt/C, respectively. A positive effect of the high specific surface area of the HCS and its interactions with metal nanoparticles and electrolyte, which promoted the mass transfer, increased the performance of Pt/HCS-P and Pt/HCS-B. The high catalytic activity showed by Pt/HCS-B and Pt/HCS-P for the ORR, even with a low-Pt content, make them promising cathode nanocatalysts for Anion Exchange Membrane Fuel Cells (AEMFC).

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