scholarly journals Synthesis of Ag-Au Nanoparticles by Galvanic Replacement and Their Morphological Studies by HRTEM and Computational Modeling

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Manuel Ramos ◽  
Domingo A. Ferrer ◽  
Russell R. Chianelli ◽  
Victor Correa ◽  
Joseph Serrano-Matos ◽  
...  
Keyword(s):  
Computational Models ◽  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Metallic Silver ◽  
Galvanic Replacement ◽  
Colloidal Structure ◽  
Morphological Studies ◽  
Transmission Electron ◽  
Potential Applications ◽  
Chloride Hydrate

Bimetallic nanoparticles are important because they possess catalytic and electronic properties with potential applications in medicine, electronics, and chemical industries. A galvanic replacement reaction synthesis has been used in this research to form bimetallic nanoparticles. The complete description of the synthesis consists of using the chemical reduction of metallic silver nitrite (AgNO3) and gold-III chloride hydrate (HAuCl) salt precursors. The nanoparticles display round shapes, as revealed by high-resolution transmission electron microscope (HRTEM). In order to better understand the colloidal structure, it was necessary to employ computational models which involved the simulations of HRTEM images.

scholarly journals Characterization Microstructural and Electrochemical of AgPd Alloy Bimetallic Nanoparticles

MRS Advances ◽  
2017 ◽  
Vol 2 (50) ◽  
pp. 2857-2863 ◽  
Author(s):  
A. Santoveña ◽  
C. Rodriguez-Proenza ◽  
J.A. Maya-Cornejo ◽  
A. Ruiz-Baltazar ◽  
D. Bahena ◽  
...  
Keyword(s):  
Bimetallic Nanoparticles ◽  
Electrochemical Characterizations ◽  
Dark Field ◽  
High Catalytic Activity ◽  
X Ray Diffraction ◽  
Bimetallic Systems ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
Potential Applications

ABSTRACTBimetallic nanoparticles are of special interest for their potential applications to fuel cells, among the bimetallic systems, AuPd bimetallic nanoparticles have received great interest as they can be widely used as effective catalysts for various electrochemical reactions. Monodisperse AgPd alloy nanoparticles were synthesized by polyol method using silver nitrate and potassium tetrachloropalladate(II) in ethylene glycol as the reducing agent at 160 °C. Structural, compositional and electrochemical characterizations of synthesized bimetallic nanoparticles were investigated. High-angle annular dark field scanning/transmission electron microscopy (HAADF-STEM) images and parallel beam X-ray diffraction (XRD) of the bimetallic nanoparticles were obtained. XRD and the contrast of the HAADF-STEM images show that the bimetallic nanoparticles have an alloy structure. Cyclic voltammetry was carried out in order to confirm the electrochemical responses of the AgPd/C electrocatalysts for methanol oxidation. Thanks to the narrow size distribution of the AgPd alloy bimetallic nanoparticles (9.15 nm) the supported AgPd/C electrocatalysts have high catalytic activity toward methanol electro-oxidation.

scholarly journals Zeolite-Assisted Shear Exfoliation of Graphite into Few-Layer Graphene

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 377 ◽  
Author(s):  
Gabriela Tubon Usca ◽  
Cristian Vacacela Gomez ◽  
Marco Guevara ◽  
Talia Tene ◽  
Jorge Hernandez ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Low Cost ◽  
Great Promise ◽  
Layer Graphene ◽  
Morphological Studies ◽  
Transmission Electron ◽  
Potential Applications ◽  
Novel Method ◽  
Inorganic Layered Materials ◽  
Few Layer Graphene

A novel method is presented to prepare few-layer graphene (FLG) in N-methyl-2-pyrrolidinone (NMP) by using a simple, low-cost and energy-effective shear exfoliation assisted by zeolite and using a cappuccino mixer to produce shear. We propose that the exfoliation of natural graphite flakes can be achieved using inelastic collisions between graphite flakes and zeolite particles in a dynamic colloidal fluid. To confirm the exfoliation of FLG, spectroscopy and morphological studies are carried out using Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Additionally, the obtained graphene shows a linear flow of current and low resistance. The proposed method shows great promise for the industrial-scale synthesis of high-quality graphene with potential applications in future graphene-based devices, and furthermore, this method can be extended to exfoliate inorganic layered materials such as BN and MoS2.

Synthesis and Characterization of Novel Au(core)-Au/Pt Alloy(shell) Nanostructure

2004 ◽  
Vol 818 ◽  
Author(s):  
Ru-Shi Liu ◽  
Hau-Ming Chen ◽  
Shu-Fen Hu
Keyword(s):  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Energy Dispersive Spectrometer ◽  
Average Diameter ◽  
Shell Layer ◽  
Plasmon Band ◽  
Transmission Electron ◽  
Pt Alloy ◽  
Different Thickness

AbstractA systematic study is reported about the amount-dependent morphology change in a series of Au-Pt bimetallic nanoparticles synthesized using chemical reduction. The amount of Au precursor is kept constant throughout whole series of compounds to obtain fixed Au core size (∼7.5 nm). The Au/Pt ratio is varied from 1/1 to 1/4 in order to synthesize Pt shell layer of different thickness. We observed a remarkable shift of surface plasmon band around 410 nm. With the aid of high resolution transmission electron microscope (HRTEM) and energy-dispersive spectrometer (EDS), the composition of shell layer is found to be Pt enriched Au-Pt alloy. As the amount of Pt increases, the Pt clusters formed a string-like shape on the surface of nanoparticles. The average diameter of these Pt clusters is about 2 nm. This special structure may exhibit unique catalytic property.

Bimetallic Alloy of Fe2O3-Ag Nanoparticles: Characterization and Structural Modeling

2016 ◽  
Vol 1816 ◽  
Author(s):  
A. Ruíz-Baltazar ◽  
R. Esparza ◽  
J.L López-Miranda ◽  
G. Rosas ◽  
R. Pérez
Keyword(s):  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Elastic Light Scattering ◽  
Bimetallic Systems ◽  
Transmission Electron ◽  
Alloy Type ◽  
Ag Particles ◽  
Chloride Hexahydrate ◽  
Nanoparticles Characterization ◽  
Synthesis Methodology

ABSTRACTThe synthesis of Fe3O4-Ag bimetallic nanoparticles by chemical reduction was carried out. Fe nanoparticles were obtained using Fe (III) Chloride hexahydrate (FeCl3•6H2O) as precursor and sodium borohydride (NaBH4) as reducing agent, subsequently, a solution of silver nitrate (AgNO3) was added to the reaction. The synthesis methodology employed in this case, is a modification of chemical reduction method. Through this procedure has been possible simplify the synthesis route used to obtain bimetallic systems such as Fe3O4-Ag. Particles with semi-spherical morphology were observed. High-resolution transmission electron microscopy (HREM), ultraviolet visible spectroscopy (UV-is) and quasi-elastic light scattering (QELS) techniques were employed for the structural characterization of Fe3O4-Ag nanostructures. Some models presented describe and prove the formation of the Fe3O4-Ag alloy type structures.

scholarly journals Synthesis and Characterization of Bifunctionalα-Fe2O3-Ag Nanoparticles

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Alvaro Ruíz-Baltazar ◽  
Simón Yobanny Reyes-López ◽  
Rodrigo Esparza ◽  
Miriam Estévez ◽  
Ángel Hernández-Martínez ◽  
...  
Keyword(s):  
Ag Nanoparticles ◽  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Theoretical Models ◽  
Hybrid Nanoparticles ◽  
Chemical Reduction Method ◽  
Transmission Electron ◽  
Chloride Hexahydrate ◽  
The Individual

The synthesis ofα-Fe2O3-Ag bimetallic nanoparticles using a novel and simplified route is presented in this work. These hybrid nanoparticles were produced using a modification of the chemical reduction method by sodium borohydride (NaBH4). Fe(III) chloride hexahydrate (FeCl3·6H2O) and silver nitrate (AgNO3) as precursors were employed. Particles with semispherical morphology and dumbbell configuration were observed. High-resolution transmission electron microscopy (HRTEM) technique reveals the structure of the dumbbell-likeα-Fe2O3-Ag nanoparticles. Some theoretical models further confirm the formation of theα-Fe2O3-Ag structures. Analysis by cyclic voltammetry reveals an interesting catalytic behavior which is associated with the combination of the individual properties of the Ag andα-Fe2O3nanoparticles.

Facile Synthesis of PtAu Nanoparticles/Graphene Nanocomposites for Direct Electrochemistry and Electrocatalysis

2013 ◽  
Vol 760-762 ◽  
pp. 750-754
Author(s):  
Li Min Lu ◽  
Ou Zhang ◽  
Tao Nie ◽  
Jing Kun Xu ◽  
Kai Xin Zhang ◽  
...  
Keyword(s):  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Electrochemical Techniques ◽  
Direct Electrochemistry ◽  
Practical Application ◽  
Detection Range ◽  
Graphene Nanocomposites ◽  
Transmission Electron ◽  
Linear Detection ◽  
Simple Chemical

PtAu bimetallic nanoparticles (NPs) were successfully synthesized on single-stranded DNA functionalized graphene nanomaterials (ss-DNA/GR) via a simple chemical reduction method. The nanocomposites (PtAu/ss-DNA/GR) were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectrometer (EDS) and electrochemical techniques. Then a sensitive dopamine (DA) sensor was fabricated based on PtAu/ss-DNA/GR nanocomposites modified glassy carbon electrode (GCE). The results of electrochemical experiments demonstrated that the sensor exhibited excellent electrocatalytic activity to the oxidation of DA. The sensor displayed wide linear detection range from 8.0×10-8 to 1.0×10-5 M and 1.0×10-5 to 5.0×10-5 M and a low detection limit of 1.0×10-8 M (S/N = 3). In addition, the sensor also showed high selectivity, good reproducibility and stability for DA detection. Thus, it is considered to be an ideal candidate for practical application.

AuCu, AgCu and AuAg Bimetallic Nanoparticles: Synthesis, Characterization and Water Remediation

MRS Advances ◽  
2016 ◽  
Vol 1 (36) ◽  
pp. 2525-2530
Author(s):  
Judith Tanori ◽  
Diana Vargas-Hernández ◽  
Elisa Martínez-Barbosa ◽  
Raúl Borja-Urby ◽  
Arturo García-Bórquez ◽  
...  
Keyword(s):  
Composite Material ◽  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Water Remediation ◽  
Natural Systems ◽  
Self Assembling ◽  
Transmission Electron ◽  
Gold Silver ◽  
Vis Spectroscopy

ABSTRACTSelf-assembling systems of amphiphilic molecules display structures similar to those of biomineralization natural systems. This allows to somehow mimic nature to synthesize nanomaterials with low polidispersity and with diverse morphologies. In this work we describe the synthesis and characterization of gold-copper, silver-copper, and gold-silver bimetallic nanoparticles by chemical reduction in self-assembling systems of two surfactants. The nanoparticles were characterized by Transmission Electron Microscopy and UV-Vis spectroscopy. We have prepared a composite material using mesoporous silica as support of the AuAg bimetallic nanoparticles. The system was used in photocatalysis experiments for water remediation applications. Our results show that the AuAg/SBA15 composite material degrades methyl orange in water from 17 ppm to 4 ppm in 30 minutes.

scholarly journals Influence of Electrochemical Pretreatment Conditions of PtCu/C Alloy Electrocatalyst on Its Activity

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1499
Author(s):  
Angelina Pavlets ◽  
Anastasia Alekseenko ◽  
Vladislav Menshchikov ◽  
Sergey Belenov ◽  
Vadim Volochaev ◽  
...  
Keyword(s):  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Methanol Electrooxidation ◽  
Oxygen Electroreduction ◽  
Potential Range ◽  
Activation Process ◽  
Transmission Electron ◽  
Prepared Material ◽  
Pretreatment Conditions ◽  
Activation Conditions

A carbon supported PtCux/C catalyst, which demonstrates high activity in the oxygen electroreduction and methanol electrooxidation reactions in acidic media, has been obtained using a method of chemical reduction of Pt (IV) and Cu (2+) in the liquid phase. It has been found that the potential range of the preliminary voltammetric activation of the PtCux/C catalyst has a significant effect on the de-alloyed material activity in the oxygen electroreduction reaction (ORR). High-resolution transmission electron microscopy (HRTEM) demonstrates that there are differences in the structures of the as-prepared material and the materials activated in different potential ranges. In this case, there is practically no difference in the composition of the PtCux-y/C materials obtained after activation in different conditions. The main reason for the established effect, apparently, is the reorganized features of the bimetallic nanoparticles’ surface structure, which depend on the value of the limiting anodic potential in the activation process. The effect of the activation conditions on the catalyst’s activity in the methanol electrooxidation reaction is less pronounced.

Microstructure of laser-irradiated, conducting Kapton polyimide

1995 ◽  
Vol 53 ◽  
pp. 502-503
Author(s):  
D. L. Callahan ◽  
Z. Ball ◽  
H. M. Phillips ◽  
R. Sauerbrey
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Film Surface ◽  
Cross Sectional ◽  
General Utility ◽  
Transmission Electron ◽  
Considerable Debate ◽  
Potential Applications

Ultraviolet laser-irradiation can be used to induce an insulator-to-conductor phase transition on the surface of Kapton polyimide. Such structures have potential applications as resistors or conductors for VLSI applications as well as general utility electrodes. Although the percolative nature of the phase transformation has been well-established, there has been little definitive work on the mechanism or extent of transformation. In particular, there has been considerable debate about whether or not the transition is primarily photothermal in nature, as we propose, or photochemical. In this study, cross-sectional optical microscopy and transmission electron microscopy are utilized to characterize the nature of microstructural changes associated with the laser-induced pyrolysis of polyimide.Laser-modified polyimide samples initially 12 μm thick were prepared in cross-section by standard ultramicrotomy. Resulting contraction in parallel to the film surface has led to distortions in apparent magnification. The scale bars shown are calibrated for the direction normal to the film surface only.

Morphological studies of linear (AB)n multiblock copolymers and their blends

1992 ◽  
Vol 50 (1) ◽  
pp. 384-385
Author(s):  
Richard J. Spontak ◽  
Steven D. Smith ◽  
Arman Ashraf
Keyword(s):  
Electron Microscopy ◽  
Microphase Separation ◽  
Multiblock Copolymers ◽  
First Order ◽  
Morphological Studies ◽  
Transmission Electron ◽  
First Order Phase Transition ◽  
Covalently Bonded ◽  
Total Molecular Weight ◽  
First Order Phase

Block copolymers are composed of sequences of dissimilar chemical moieties covalently bonded together. If the block lengths of each component are sufficiently long and the blocks are thermodynamically incompatible, these materials are capable of undergoing microphase separation, a weak first-order phase transition which results in the formation of an ordered microstructural network. Most efforts designed to elucidate the phase and configurational behavior in these copolymers have focused on the simple AB and ABA designs. Few studies have thus far targeted the perfectly-alternating multiblock (AB)n architecture. In this work, two series of neat (AB)n copolymers have been synthesized from styrene and isoprene monomers at a composition of 50 wt% polystyrene (PS). In Set I, the total molecular weight is held constant while the number of AB block pairs (n) is increased from one to four (which results in shorter blocks). Set II consists of materials in which the block lengths are held constant and n is varied again from one to four (which results in longer chains). Transmission electron microscopy (TEM) has been employed here to investigate the morphologies and phase behavior of these materials and their blends.

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