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.

scholarly journals Facile and Rapid Synthesis of Ultrafine PtPd Bimetallic Nanoparticles and Their High Performance toward Methanol Electrooxidation

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Tiantian Xia ◽  
Hanrui Shen ◽  
Gang Chang ◽  
Yuting Zhang ◽  
Honghui Shu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Performance ◽  
Direct Methanol Fuel Cells ◽  
Bimetallic Nanoparticles ◽  
Methanol Electrooxidation ◽  
X Ray ◽  
Transmission Electron ◽  
Composition And Structure ◽  
Direct Methanol

Uniform and sub-10 nm size bimetallic PtPd nanoparticles (NPs) have been synthesized via a simple and facile method without using any surfactants at an ambient temperature. As a green and clean reductive agent, ascorbic acid (AA) was employed for the coreduction of K2PtCl4and K2PdCl4in aqueous solution. The morphology, composition, and structure of PtPd NPs had been characterized by transmission electron microscopy (TEM), field emission high resolution transmission electron microscopy (FE-HRTEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscope (XPS). Comparing with both the monometallic Pt and Pd, the as-prepared alloy nanoparticles show superior electrocatalytic activity and better tolerance against poisoning by intermediates generated during methanol electrooxidation, which makes them a promising electrocatalysts for direct methanol fuel cells (DMFCs). Meanwhile, the green and simple approach could be easily extended to the manufacture of bimetallic or trimetallic alloy nanomaterials.

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 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 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.

SEM and Auger microanalysis studies of Cu-Be dynode surfaces at each activation condition

1978 ◽  
Vol 36 (1) ◽  
pp. 524-525
Author(s):  
T. Koshikawa ◽  
Y. Fujii ◽  
E. Sugata ◽  
F. Kanematsu
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Life Time ◽  
Activation Process ◽  
Beam Diameter ◽  
Activation Temperature ◽  
Electron Multiplier ◽  
Activation Condition ◽  
Activation Conditions

The Cu-Be alloys are widely used as the electron multiplier dynodes after the adequate activation process. But the structures and compositions of the elements on the activated surfaces were not studied clearly. The Cu-Be alloys are heated in the oxygen atmosphere in the usual activation techniques. The activation conditions, e.g. temperature and O2 pressure, affect strongly the secondary electron yield and life time of dynodes.In the present paper, the activated Cu-Be dynode surfaces at each condition are investigated with Scanning Auger Microanalyzer (SAM) (primary beam diameter: 3μmϕ) and SEM. The commercial Cu-Be(2%) alloys were polished with Cr2O3 powder, rinsed in the distilled water and set in the vacuum furnance.Two typical activation condition, i.e. activation temperature 730°C and 810°C in 5x10-3 Torr O2 pressure were chosen since the formation mechanism of the BeO film on the Cu-Be alloys was guessed to be very different at each temperature from the results of the secondary electron emission measurements.

scholarly journals Removal of hexavalent chromium from wastewater by Cu/Fe bimetallic nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jien Ye ◽  
Yi Wang ◽  
Qiao Xu ◽  
Hanxin Wu ◽  
Jianhao Tong ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Particle Surface ◽  
Zerovalent Iron ◽  
Order Model ◽  
X Ray ◽  
Nanoscale Zerovalent Iron

AbstractPassivation of nanoscale zerovalent iron hinders its efficiency in water treatment, and loading another catalytic metal has been found to improve the efficiency significantly. In this study, Cu/Fe bimetallic nanoparticles were prepared by liquid-phase chemical reduction for removal of hexavalent chromium (Cr(VI)) from wastewater. Synthesized bimetallic nanoparticles were characterized by transmission electron microscopy, Brunauer–Emmet–Teller isotherm, and X-ray diffraction. The results showed that Cu loading can significantly enhance the removal efficiency of Cr(VI) by 29.3% to 84.0%, and the optimal Cu loading rate was 3% (wt%). The removal efficiency decreased with increasing initial pH and Cr(VI) concentration. The removal of Cr(VI) was better fitted by pseudo-second-order model than pseudo-first-order model. Thermodynamic analysis revealed that the Cr(VI) removal was spontaneous and endothermic, and the increase of reaction temperature facilitated the process. X-ray photoelectron spectroscopy (XPS) analysis indicated that Cr(VI) was completely reduced to Cr(III) and precipitated on the particle surface as hydroxylated Cr(OH)3 and CrxFe1−x(OH)3 coprecipitation. Our work could be beneficial for the application of iron-based nanomaterials in remediation of wastewater.

scholarly journals Size Control of Synthesized Silver Nanoparticles by Simultaneous Chemical Reduction and Laser Fragmentation in Origanum majorana Extract: Antibacterial Application

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2326
Author(s):  
Entesar Ali Ganash ◽  
Reem Mohammad Altuwirqi
Keyword(s):  
Silver Nanoparticles ◽  
Irradiation Time ◽  
Chemical Reduction ◽  
Size Control ◽  
Reduction Process ◽  
Laser Wavelength ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Transmission Electron ◽  
Origanum Majorana

In this work, silver nanoparticles (Ag NPs) were synthesized using a chemical reduction approach and a pulsed laser fragmentation in liquid (PLFL) technique, simultaneously. A laser wavelength of 532 nm was focused on the as produced Ag NPs, suspended in an Origanum majorana extract solution, with the aim of controlling their size. The effect of liquid medium concentration and irradiation time on the properties of the fabricated NPs was studied. While the X-ray diffraction (XRD) pattern confirmed the existence of Ag NPs, the UV–Vis spectrophotometry showed a significant absorption peak at about 420 nm, which is attributed to the characteristic surface plasmon resonance (SPR) peak of the obtained Ag NPs. By increasing the irradiation time and the Origanum majora extract concentration, the SPR peak shifted toward a shorter wavelength. This shift indicates a reduction in the NPs’ size. The effect of PLFL on size reduction was clearly revealed from the transmission electron microscopy images. The PLFL technique, depending on experimental parameters, reduced the size of the obtained Ag NPs to less than 10 nm. The mean zeta potential of the fabricated Ag NPs was found to be greater than −30 mV, signifying their stability. The Ag NPs were also found to effectively inhibit bacterial activity. The PLFL technique has proved to be a powerful method for controlling the size of NPs when it is simultaneously associated with a chemical reduction process.

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