scholarly journals ULTRAFINECOPPER AND NICKEL POWDERS INTHE ELECTRO-CATALYTICHYDROGENATIONOF ORGANIC COMPOUNDS

2021 ◽  
Vol 74 (2) ◽  
pp. 32-48
Author(s):  
E.A. SOBOLEVA ◽  
◽  
Ya.A. VISURKHANOVA ◽  
N.M. IVANOVA ◽  
М.Е. BEISENBEKOVA ◽  
...  
Keyword(s):  
Electrocatalytic Activity ◽  
Chemical Reduction ◽  
Ethanol Solution ◽  
Metal Powders ◽  
Nickel Powders ◽  
Polymer Stabilizer ◽  
Skeletal Copper ◽  
Ultrafine Copper ◽  
Copper Cations ◽  
Polymer Stabilizers

Ultrafine copper and nickel powders are synthesized by a chemical reduction of the metal cations from their salts in an aqueous ethanol solution without and with the addition of a polymer stabilizer (polyvinylpyrrolidone and polyvinyl alcohol). The structure and morphological features of the prepared metal powders were investigated by X-ray phase analysis and electron microscopy. The electrocatalytic properties of the Cu and Ni powders have been studied in the electrohydrogenation of acetophenone, nitrobenzene, p-nitroaniline, and cyclohexanone. A higher electrocatalytic activity of Cu powders, as well as skeletal copper, was established in the electrohydrogenation of the first three of the listed compounds in comparison with nickel powders, which is explained by the ability of copper cations to be reduced from its oxides in the electrochemical system under investigation. It is shown that the use of polymer stabilizers in the synthesis of Cu and Ni powders contributes to reducing metal particle sizes, but does not increase the electrocatalytic activity of the corresponding metal powders.

Aggregation Characteristics of Cu and Ag Nanoparticles in Presence of Starch as the Polymer Stabilizer

2010 ◽  
Vol 123-125 ◽  
pp. 615-618 ◽  
Author(s):  
Indrajit Sinha ◽  
Manjeet Singh ◽  
Rajiv Kumar Mandal
Keyword(s):  
Small Molecule ◽  
Ag Nanoparticles ◽  
Growth Models ◽  
Chemical Reduction ◽  
Cluster Aggregation ◽  
Diffusion Limited ◽  
X Ray Scattering ◽  
Polymer Stabilizer ◽  
Aqueous Conditions ◽  
Diffusion Limited Cluster Aggregation

This presentation deals with the aggregation characteristics of Cu and Ag nanoparticles in presence of starch as the polymer stabilizer. Uncontrolled aggregation of the destabilized nanoparticles offers problem for applications based on surface plasmon activity. Polymer or small molecule surfactants are used to control nature of aggregation of nanoparticles produced by chemical reduction synthesis routes. Different growth models such as diffusion limited cluster aggregation (DLCA), reaction limited cluster aggregation (RLCA) proposed to explain the formation of fractal colloidal aggregates do not account for aggregate formation in presence of polymer or small molecule surfactants. We shall be discussing the role of starch on the aggregation characteristics of copper and silver nanoparticles formed by chemical reduction in aqueous conditions. The effect of NaOH concentration and consequently the pH on such aggregation kinetics during such synthesis is delineated. We use small angle x-ray scattering (SAXS) to quantitatively understand different aspects of aggregation behavior.

Synthesis of Fine Nickel Powders by Solvothermal Method

2007 ◽  
Vol 334-335 ◽  
pp. 1145-1148 ◽  
Author(s):  
Yin Ye ◽  
Fang Li Yuan ◽  
Li Min Zhou ◽  
Hai Tao Huang
Keyword(s):  
Thermal Stability ◽  
Chemical Reduction ◽  
Spherical Shape ◽  
Butyl Alcohol ◽  
Nickel Powders ◽  
Good Crystallinity ◽  
Average Size ◽  
Solvothermal Conditions ◽  
Thermal Stability Of ◽  
Fine Nickel

Fine nickel powders have been prepared by chemical reduction between nickel acetate and alcohol under solvothermal conditions. The effect of adding surfactant and varying solvent on the particle size of the as-synthesized nickel powders have been explored. SEM, XRD and TG were employed to characterize the size, morphology, crystalline structure and the thermal stability of the as-synthesized nickel powders. It is revealed that the FCC-structured nickel powders are of uniform spherical shape with good crystallinity and thermal stability. Typically, nickel powders with an average size of 300 nm were obtained at 200°C for 8 h using 0.04 mol/L solution of Ni(CH3COO)2·4H2O in n-butyl alcohol under solvothermal conditions.

Preparation and Characteristic of Ultrafine Copper-Based Powders Reduced by a Two-Step Reduction Method

2020 ◽  
Vol 1003 ◽  
pp. 122-127
Author(s):  
Jia Yuan Chang ◽  
Ru Yue Guo ◽  
Mu Hua Li ◽  
Hua Yi Li
Keyword(s):  
Electron Microscope ◽  
Copper Powder ◽  
Cuprous Oxide ◽  
Reduction Method ◽  
Ph Value ◽  
Chemical Reduction ◽  
Pure Copper ◽  
Glucose Content ◽  
Transmission Electron ◽  
Ultrafine Copper

In this study, the ultrafine copper-based powders were fabricated by a facile two-step chemical reduction method. Glucose (C6H12O6) and ascorbic acid (AA) were taken as a pre-reductant and a second reductant, respectively. Polyvinylpyrrolidone (PVP) was applied as the capping agent. Effects of parameters, such as glucose content, PVP content and PH value on the ultimate reduction products were analyzed. Microstructure and composition of the products were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). It was found that when the amount of glucose was increased from half to full and then excessive, the powder gradually changed from flaky to spherical, from pure copper powder to a mixture of copper and cuprous oxide (Cu2O). With the amount of PVP increasing from 0g to 0.64 g, the shape of the pure copper powder changed from cubic to spherical or HYPERLINK "javascript:void (0);" icosahedron. When the PH value changed from 10-14, the powder changed from spherical to regular octahedron and Irregular polyhedron, from pure copper powder to pure cuprous oxide powder. Therefore, copper-based powders with different morphologies and different compositions can be prepared by changing PH value and the amount of reductant.

Synthesis of Mono-Dispersed Fine Spherical Silver Powders by Chemical Reduction Method

2007 ◽  
Vol 539-543 ◽  
pp. 2782-2786 ◽  
Author(s):  
Jong Gwan Ahn ◽  
Dong Jin Kim ◽  
Jae Ryeong Lee ◽  
H.S. Jung ◽  
Byoung Gyu Kim
Keyword(s):  
Reduction Method ◽  
Chemical Reduction ◽  
Silver Powder ◽  
Nitrate Solution ◽  
Particle Morphology ◽  
Silver Nitrate Solution ◽  
Phase Method ◽  
Metal Powders ◽  
Chemical Reduction Method ◽  
Liquid Phase Method

The synthesis of spherical silver powders by chemical reduction method was investigated. Conductive metal pastes to have good properties in adhesion, stability, and conductivity, it is very important to control the purity, size, and shape of metal particles. In the present study, proper methods to control the properties of micron sized metal powders for conductive pastes are investigated. Chemical reduction method in aqueous solution was adapted to produce silver powder. The effects of reaction time, concentration of reductant and additives, and stirring speed were investigated, in experimental. Fine spherical silver powder of 0.5 to 3 ㎛ were synthesized from silver nitrate solution with hydroquinone as a reducing additive by liquid phase method, and some variables and reaction mechanism in conjunction with the particle morphology and size were studied.

scholarly journals Characterization of Ni-Cd Nanostructured System Obtained by Chemical Reduction of Salts

2016 ◽  
Vol 17 (4) ◽  
pp. 275 ◽  
Author(s):  
V.M. Pugachev ◽  
Yu.A. Zaharov ◽  
A.S. Valnyukova ◽  
V.G. Dodonov
Keyword(s):  
Chemical Reduction ◽  
Structural Parameters ◽  
Reduction Process ◽  
Metal Powders ◽  
X Ray Diffraction ◽  
X Ray ◽  
Initial Stage ◽  
Fcc Lattice ◽  
High Alkalinity

<p>The process of obtaining of highly dispersed metal powders of Ni-Cd system by reduction of their salts by hydrazine in aqueous medium at high alkalinity was investigated. The possibility of production metal powders containing up to 50 mol% of cadmium is established and conditions for their synthesis are optimized. Phase composition, structural parameters, dispersity of solid products during the reduction process were studied by X-ray diffraction (XRD) and SAXS. The formation of metal solid solutions with FCC lattice contradicts to the known phase diagram for Ni-Cd and may be explained by increasing the energy of the particles in the nanostate. The formation of intermetallide NiCd<sub>5</sub> in the studied compositions area is caused by sequential character of reduction process; as a result the metal product on the initial stage of reduction is significantly enriched with cadmium.</p>

Preparation of Nanocrystalline Nickel Powders by Chemical Reduction in Nonaqueous Media

2007 ◽  
pp. 2107-2110
Author(s):  
Ji Un Im ◽  
Seong Yup Jun ◽  
Seong Soo Hong ◽  
Gun Dae Lee ◽  
Kwang Ho Kim ◽  
...  
Keyword(s):  
Chemical Reduction ◽  
Nanocrystalline Nickel ◽  
Nonaqueous Media ◽  
Nickel Powders

Limit for Controlling Stabilization of Cu Powder Prepared from Cu2o-H2O System

2007 ◽  
Vol 558-559 ◽  
pp. 741-746 ◽  
Author(s):  
Hoang Tri Hai ◽  
Dong Jin Kim ◽  
Y.D. Kim ◽  
Chong Oh Kim ◽  
Hun Saeng Chung ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Chemical Reduction ◽  
Sodium Pyrophosphate ◽  
Critical Conditions ◽  
Palladium Chloride ◽  
Strong Impact ◽  
Copper Powders ◽  
Polymer Stabilizer ◽  
Wet Chemical

Ultrafine dispersed copper powders were prepared from copper (I) oxide (Cu2O) slurry by a wet chemical reduction with hydrazine as a reductant. Palladium chloride (PdCl2) was used as a nucleator along with its polymer stabilizer, polyvinylpyrrolidone (PVP). Sodium pyrophosphate (Na4O7P2) was added as a surfactant. It was found that the use of Cu2O and Na4O7P2 exhibit very strong impact on dispersity of the prepared Cu powders. In this study, we indicate the critical conditions at which the particles aggregation still occurs even though the powders produced at high zeta potential resulted from an appropriate addition of Na4O7P2.

Synthesis of amorphous boride nanosheets by the chemical reduction of Prussian blue analogs for efficient water electrolysis

2018 ◽  
Vol 6 (46) ◽  
pp. 23289-23294 ◽  
Author(s):  
Ting He ◽  
Jean Marie Vianney Nsanzimana ◽  
Ruijuan Qi ◽  
Jun-Ye Zhang ◽  
Mao Miao ◽  
...  
Keyword(s):  
Prussian Blue ◽  
Water Splitting ◽  
Electrocatalytic Activity ◽  
Chemical Reduction ◽  
Water Electrolysis ◽  
Nickel Boride ◽  
Overall Water Splitting ◽  
Cobalt Nickel ◽  
Prussian Blue Analogs ◽  
Cost Efficient

Amorphous cobalt–nickel boride nanosheets are synthesised by the chemical reduction of Prussian blue analogs, and demonstrate comparable and bifunctional electrocatalytic activity for cost-efficient overall water splitting.

A Study for Synthesis of Nanobelt and Nanowire Nickel Powders by Wet Chemical Method

2007 ◽  
Vol 544-545 ◽  
pp. 83-86
Author(s):  
Seung Yup Jeon ◽  
Eun Ju Chae ◽  
Won Ki Lee ◽  
Gun Dae Lee ◽  
Seong Soo Hong ◽  
...  
Keyword(s):  
Chemical Reduction ◽  
Wet Chemical Method ◽  
Nickel Ion ◽  
Sodium Tartrate ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Nickel Powders ◽  
Key Factor ◽  
Wet Chemical ◽  
Anion Surfactant

Ni nanosheet has been prepared at various temperature and time with anion surfactant by chemical reduction of the nickel ion complexes formed from complexing reagent in a pressurized vessel. Sample was characterized by the means of an X-ray diffractomer (XRD), a field emission scanning electron microscopy (FESEM), an energy dispersive X-ray spectrometer (EDS), a selected-area electron diffraction (SAED) and a high sensitive magnetometer (HSM). The use of SDBS and sodium tartrate could be a key factor for the formation and growth of Ni nanosheet.

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