Improved Electrochemical Durability of PtRuAu/C Catalyst Synthesized by Radiolytic Process

2011 ◽  
Vol 1311 ◽  
Author(s):  
Satoru Kageyama ◽  
Akio Murakami ◽  
Satoshi Seino ◽  
Takashi Nakagawa ◽  
Hideo Daimon ◽  
...  
Keyword(s):  
Linear Sweep Voltammetry ◽  
X Ray Diffraction ◽  
Oxidation Activity ◽  
X Ray ◽  
Transmission Electron ◽  
Radiolytic Process ◽  
Significant Difference ◽  
Direct Methanol ◽  
X Ray Absorption ◽  
Methanol Fuel Cell

ABSTRACTNanoparticle catalyst of PtRuAu/C for direct methanol fuel cell anodes was synthesized by a radiolytic process. Its methanol oxidation activity and the electrochemical durability were evaluated by using the linear sweep voltammetry and the cyclic voltammety. The Au addition significantly improved the durability in comparison with PtRu/C catalyst without losing its high activity. The atomic structure was characterized with techniques of the transmission electron microscopy, the X-ray diffraction, the X-ray fluorescence spectroscopy and the X-ray absorption fine structure. These results implied that the arrangement of Pt and Ru atoms in the PtRuAu/C has no significant difference from that without Au, possessing a structure of Pt rich core and PtRu alloy shell. We concluded that the improvement in durability could originate from these PtRu nanoparticles decorated with Au, but not from particles with high Au contents.

EXAFS Study on Nanosized PtRu Catalyst for Direct Methanol Fuel Cell

2005 ◽  
Vol 900 ◽  
Author(s):  
Hiroaki Nitani ◽  
Takahiro Ono ◽  
Yusuke Honda ◽  
Akiko Koizumi ◽  
Takashi Nakagawa ◽  
...  
Keyword(s):  
Precursor Solution ◽  
Polyol Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Direct Methanol ◽  
Ptru Catalyst ◽  
Exafs Study ◽  
Ptru Catalysts ◽  
X Ray Absorption

ABSTRACTNano-sized PtRu catalysts supported on carbon nanoparticles were synthesized by a polyol process. The PtRu catalyst prepared at pH=3 indicated higher catalysis for methanol oxidation than one prepared at pH=5.5. The samples were analyzed by techniques of the extended X-ray absorption fine structure (EXAFS), transmission electron microscope (TEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF). Their results showed that the pH of the precursor solution during the polyol process affected the substructure of the PtRu nanoparticles. The correlation of the substructure with the catalytic activity was studied.

scholarly journals Structural Evolution in Wet Mechanically Alloyed Co-Fe-(Ta,W)-B Alloys

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 800
Author(s):  
Vladimír Girman ◽  
Maksym Lisnichuk ◽  
Daria Yudina ◽  
Miloš Matvija ◽  
Pavol Sovák ◽  
...  
Keyword(s):  
Structural Changes ◽  
Magnetic Measurements ◽  
Structural Evolution ◽  
High Energy ◽  
Control Agent ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Transmission Electron ◽  
X Ray Absorption

In the present study, the effect of wet mechanical alloying (MA) on the glass-forming ability (GFA) of Co43Fe20X5.5B31.5 (X = Ta, W) alloys was studied. The structural evolution during MA was investigated using high-energy X-ray diffraction, X-ray absorption spectroscopy, high-resolution transmission electron microscopy and magnetic measurements. Pair distribution function and extended X-ray absorption fine structure spectroscopy were used to characterize local atomic structure at various stages of MA. Besides structural changes, the magnetic properties of both compositions were investigated employing a vibrating sample magnetometer and thermomagnetic measurements. It was shown that using hexane as a process control agent during wet MA resulted in the formation of fully amorphous Co-Fe-Ta-B powder material at a shorter milling time (100 h) as compared to dry MA. It has also been shown that substituting Ta with W effectively suppresses GFA. After 100 h of MA of Co-Fe-W-B mixture, a nanocomposite material consisting of amorphous and nanocrystalline bcc-W phase was synthesized.

Preparation and Characterization of Pt/Superfine Mesocarbon Microbead Powers Electrocatalysts

2005 ◽  
Vol 3 (3) ◽  
pp. 358-360 ◽  
Author(s):  
Jia Rong-Li ◽  
Wang Cheng-Yang ◽  
Zhu Bin
Keyword(s):  
Reduction Method ◽  
Direct Methanol Fuel Cells ◽  
Electrochemical Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Platinum Particles ◽  
Platinum Electrocatalyst ◽  
Direct Methanol

Superfine mesocarbon microbead powders (SFMCMBs) as the new supports for platinum electrocatalysts were first investigated. The Pt∕SFMCMB electrocatalysts were prepared by an impregnation-reduction method, with hexachloroplatinic acid as the platinum precursor and formaldehyde as the reducing agent. The catalysts were characterized with x-ray diffraction (XRD), field emission gun transmission electron microscope (TEM), and electrochemical analysis. TEM photos showed the platinum particles were dispersed uniformly on the surface of SFMCMBs and there existed a little aggregation of platinum particles in the Pt∕SFMCMB catalysts. The TEM photos showed the existence of the platinum on the supports where the average platinum particle size were 4-6nm. The electrochemical analysis proved that SFMCMBs are excellent candidates to be used as the support of platinum electrocatalyst for methanol electrochemical oxidation as the potential catalyst candidate for direct methanol fuel cells (DMFCs).

Size dependent behavior of Fe3O4crystals during electrochemical (de)lithiation: an in situ X-ray diffraction, ex situ X-ray absorption spectroscopy, transmission electron microscopy and theoretical investigation

2017 ◽  
Vol 19 (31) ◽  
pp. 20867-20880 ◽  
Author(s):  
David C. Bock ◽  
Christopher J. Pelliccione ◽  
Wei Zhang ◽  
Janis Timoshenko ◽  
K. W. Knehr ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Dependent Behavior ◽  
X Ray Absorption

Crystal and atomic structural changes of Fe3O4upon electrochemical (de)lithiation were determined.

scholarly journals Observation and Characterization of Fragile Organometallic Molecules Encapsulated in Single-Wall Carbon Nanotubes

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Daisuke Ogawa ◽  
Ryo Kitaura ◽  
Takeshi Saito ◽  
Shinobu Aoyagi ◽  
Eiji Nishibori ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
High Yield ◽  
Single Wall Carbon Nanotubes ◽  
X Ray Diffraction ◽  
Single Wall Carbon ◽  
X Ray ◽  
Transmission Electron ◽  
Organometallic Molecules ◽  
X Ray Absorption

Thermally fragile tris(η5-cyclopentadienyl)erbium (ErCp3) molecules are encapsulated in single-wall carbon nanotubes (SWCNTs) with high yield. We realized the encapsulation of ErCp3with high filling ratio by using high quality SWCNTs at an optimized temperature under higher vacuum. Structure determination based on high-resolution transmission electron microscope observations together with the image simulations reveals the presence of almost free rotation of each ErCp3molecule in SWCNTs. The encapsulation is also confirmed by X-ray diffraction. Trivalent character of Er ions (i.e., Er3+) is confirmed by X-ray absorption spectrum.

Thiol-Capped CdSe and CdTe Nanoclusters: Synthesis by a Wet Chemical Route, Structural and Optical Properties

1998 ◽  
Vol 536 ◽  
Author(s):  
A. L. Rogach ◽  
A Eychmüller ◽  
J. Rockenberger ◽  
A. Kornowski ◽  
H. Weller ◽  
...  
Keyword(s):  
Particle Size ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Chemical Route ◽  
X Ray ◽  
Stabilizing Agents ◽  
Transmission Electron ◽  
Wet Chemical ◽  
Wet Chemical Route ◽  
X Ray Absorption

AbstractCdSe and CdTe nanoclusters were formed in aqueous solutions at moderate temperatures by a wet chemical route in the presence of thiols as effective stabilizing agents. The nature of the stabilizing agent (thioalcohols or thioacids) had an important influence on the particle size and largely determined the photoluminescence properties. The nanoclusters were characterized by means of UV-vis absorption and photoluminescence spectroscopy, powder X-ray diffraction, high resolution transmission electron microscopy, and extended X-ray absorption fine structure measurements. CdSe and CdTe nanoclusters were crystalline, in the cubic zincblende phase, with mean sizes in the range of 2 to 5 nm depending on the preparative conditions and the postpreparative size-selective fractionation, and showed pronounced electronic transitions in the absorption spectra. Thioglycerol-stabilized CdTe nanoclusters possessed sharp band-egde photoluminescence being tunable with particle size.

Structural, morphological, and magnetic study of nanocrystalline cobalt-copper powders synthesized by the polyol process

1995 ◽  
Vol 10 (6) ◽  
pp. 1546-1554 ◽  
Author(s):  
G.M. Chow ◽  
L.K. Kurihara ◽  
K.M. Kemner ◽  
P.E. Schoen ◽  
W.T. Elam ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Copper Powders ◽  
Face Centered ◽  
Increasing Temperature ◽  
X Ray Absorption

Nanocrystalline CoxCu100−x (4 ⋚ x ⋚ 49 at. %) powders were prepared by the reduction of metal acetates in a polyol. The structure of powders was characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), extended x-ray absorption fine structure (EXAFS) spectroscopy, solid-state nuclear magnetic resonance (NMR) spectroscopy, and vibrating sample magnetometry (VSM). As-synthesized powders were composites consisting of nanoscale crystallites of face-centered cubic (fcc) Cu and metastable face-centered cubic (fcc) Co. Complementary results of XRD, HRTEM, EXAFS, NMR, and VSM confirmed that there was no metastable alloying between Co and Cu. The NMR data also revealed that there was some hexagonal-closed-packed (hcp) Co in the samples. The powders were agglomerated, and consisted of aggregates of nanoscale crystallites of Co and Cu. Upon annealing, the powders with low Co contents showed an increase in both saturation magnetization and coercivity with increasing temperature. The results suggested that during preparation the nucleation of Cu occurred first, and the Cu crystallites served as nuclei for the formation of Co.

Doping and Characterisation of Nanocrystalline Materials

2007 ◽  
Vol 128 ◽  
pp. 61-72
Author(s):  
Th. Wichert ◽  
Z. Guan
Keyword(s):  
Nanocrystalline Materials ◽  
Local Information ◽  
Atomic Scale ◽  
Radioactive Isotopes ◽  
Correlation Technique ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Significant Process ◽  
X Ray Absorption

The synthesis behaviour and characterisation of nanocrystalline materials is presented. The materials synthesised are ZnO and InP doped with shallow donors and acceptors, respectively. Characterisation was performed with radioactive isotopes using the perturbed γγ angular correlation technique (PAC), thereby yielding local information on an atomic scale. The characterisation was supplemented by X-ray diffraction, transmission electron microscopy, UV/VIS absorption spectroscopy, photoluminescence spectroscopy, and extended X-ray absorption fine structure spectroscopy. It was shown that the successful incorporation of dopants in nanocrystalline ZnO and InP requires annealing at temperatures at which the growth of the nanocrystals in the sample becomes a significant process.

PtRu-SiO2-TiO2/C Anode Electrocatalyst for Direct Methanol Fuel Cell

2011 ◽  
Vol 287-290 ◽  
pp. 1369-1374 ◽  
Author(s):  
Jian Feng Ju ◽  
Dong Hui Wu ◽  
Yu Jun Shi
Keyword(s):  
Fuel Cell ◽  
Methanol Oxidation ◽  
Direct Methanol Fuel Cell ◽  
Nitrogen Adsorption ◽  
Surface Characteristics ◽  
Cyclic Voltammograms ◽  
Oxidation Activity ◽  
Transmission Electron ◽  
Direct Methanol ◽  
Methanol Fuel Cell

The PtRu-SiO2-TiO2/C anode electrocatalyst ( loading 10wt% PtRu ) of direct methanol fuel cell is prepared by the surface reductive deposition method, using Vulcan XC-72 carbon black coated with nanometer SiO2-TiO2 (SiO2-TiO2/C) as the isotopic carrier. The surface characteristics of nanometer SiO2-TiO2 is studied through nitrogen adsorption, which shows that it is of porous structure together with large surface area, that is benefit to enhance the activity of SiO2-TiO2 and the dispersion of PtRu nanoparticle on the carrier of SiO2-TiO2/C. X-ray diffraction( XRD ) and transmission electron microscopy( TEM ) are used to characterize the catalyst. The PtRu nanoparticle homodisperse in SiO2-TiO2/C carrier with diameter around 2.4 nm. Cyclic voltammograms and chronoamperograms are conducted to compare the electrochemical methanol oxidation activity of the PtRu-SiO2-TiO2/C catalyst with the commercial PuRu/C catalyst ( 20 wt% of PtRu ). The results show that PtRu-SiO2-TiO2/C has higher catalytic activity and anti-poisoning ability for methanol oxidation, the addition of porous SiO2-TiO2 can replace the PtRu to some extent, comparing with the commercial PuRu/C catalyst, not only the loading of PtRu has been cut down 50%, but also the electro-oxidizing activity of methanol improved. The electro-oxidizing mechanism is basically analyzed.

Hydrothermal Synthesis and Electrocatalytic Property for H2O2 Reduction of Co3O4 Nanocubes

2011 ◽  
Vol 311-313 ◽  
pp. 477-480
Author(s):  
Zhi Ai Yang ◽  
Li Jin Feng ◽  
Xia Wang ◽  
Rong Ma ◽  
Jian Ping Sun ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Process ◽  
Linear Sweep Voltammetry ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
Linear Sweep ◽  
Electrocatalytic Property ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Subscript textThe Co3O4 nanocubes were synthesized by hydrothermal process. The products are characterized in detail by multiform techniques: scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray analysis. The results show that the products are uniform nanocubes with an average crystallite size about 20-40 nm. Electrocatalytic property of the prepared Co3O4 nanocubes was characterized by linear sweep voltammetry. LSV results indicate that Co3O4 nanocubes exhibit a remarkable electrocatalytic activity for the H2O2 reduction.

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