scholarly journals Synthesis and Characterization of Cobalt Nanoparticles Using Hydrazine and Citric Acid

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
S. A. Salman ◽  
T. Usami ◽  
K. Kuroda ◽  
M. Okido
Keyword(s):  
Citric Acid ◽  
Reduction Method ◽  
Spherical Shape ◽  
Reduction Reaction ◽  
Cobalt Nanoparticles ◽  
Cobalt Sulfate ◽  
Hexagonal Close Packed ◽  
Phase Reduction ◽  
Large Particles

Cobalt nanoparticles were produced by employing the liquid-phase reduction method and hydrazine. The effect of citric acid additives on the formation and growth mechanism of cobalt nanoparticles was investigated using polarization methods. The cobalt nanoparticles produced in 0.2 M cobalt sulfate and 5 M hydrazine at 298 K had a spherical shape with a diameter of 400 nm. The dendritic nanoparticles formed with the decreasing of hydrazine concentration at 298 K. On the other hand, dendritic large particles are confirmed at 353 K. It was confirmed that the reduction reaction progressed with the addition of citric acid, and a hexagonal close-packed (εCo) phase was formed.

Synthesis and Characterization of Poly(2-acrylamido-2-methyl propyl sulfonic acid-co-2-hydroxyethyl methclate)/ Silver Nanoparticle Composite Hydrogel as Catalysts for the Reduction of 4-Nitrophenol

2014 ◽  
Vol 809-810 ◽  
pp. 59-66
Author(s):  
Yun Long Li ◽  
Bin Huang Liu ◽  
Song Bai Lin
Keyword(s):  
Sulfonic Acid ◽  
Reduction Method ◽  
Catalytic Properties ◽  
Reduction Reaction ◽  
Composite Hydrogel ◽  
Synthesis And Characterization ◽  
In Situ Reduction ◽  
End Group

A novel kind of AgNPs catalyst was synthesized by in-situ reduction method using poly(2-acrylamido-2-methyl propyl sulfonic acid-co-2-hydroxyethyl methclate) [short as P(AMPS-co-HEMA)] hydrogel as matrices and AgNO3as a metal precursor. The structure of the composite hydrogel was characterized by Scan Electrical Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The results showed that AgNPs were binded with end group and most of the particles were isolated and uniformly distributed on the P(AMPS-co-HEMA). The catalytic properties in the reduction reaction of 4-nitrophenol(shorted as 4-NP) to 4-aminophenol(shorted as 4-AP) were studied in detail, and the result showed that conversion rate and conversion efficiency attained 97.56% and 0.9671 mmol/g·min when the amount of AgNPs was 9mg, [NaBH4] was 2.0×10−1mol/L, [4-NP] was 2.0×10−2mol/L and the total volume of solution was 50 mL, respectively.

Synthesis and Characterization of Palladium and Palladium–Cobalt Nanoparticles on Vulcan XC-72R for the Oxygen Reduction Reaction

2013 ◽  
Vol 5 (22) ◽  
pp. 11603-11612 ◽  
Author(s):  
Lisandra Arroyo-Ramírez ◽  
Rubenier Montano-Serrano ◽  
Tatiana Luna-Pineda ◽  
Félix R. Román ◽  
Raphael G. Raptis ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Reduction Reaction ◽  
Cobalt Nanoparticles ◽  
Synthesis And Characterization

Preparation and Characterization of Nickel Nanopowder for Conductive Pastes

2011 ◽  
Vol 347-353 ◽  
pp. 3485-3488
Author(s):  
Hui Ru Qin ◽  
Ji Min Xie ◽  
Jun Jie Jing ◽  
Wen Hua Li ◽  
Zhi Feng Jiang
Keyword(s):  
Electron Microscopy ◽  
Hydrazine Hydrate ◽  
Spherical Shape ◽  
Nickel Acetate ◽  
X Ray Diffraction ◽  
Phase Reduction ◽  
Transmission Electron ◽  
Nickel Particles ◽  
Nickel Nanopowder

In this paper, nickel nanopowder was prepared by liquid phase reduction method, where nickel acetate and hydrazine hydrate was used as nickel source and reducing agent, respectively. The resulting Ni nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM). The results showed that nickel acetate can be effectively reduced by hydrazine hydrate. The as-prepared nickel nanoparticles are in spherical shape, with size ranging from 100 to 200nm and good dispersion. By changing the reaction conditions, the morphology and size of nickel particles can be controlled. The synthesized nickel nanopowders meet the general requirements of nickel powder that would be used for conductive paste, which can be prepared for nickel-based conductive paste. This method has some advantages such as inexpensive, non-pollution to environment; it can be used for industry.

scholarly journals Synthesis of Cobalt-Nickel Nanoparticles via a Liquid-Phase Reduction Process

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
T. Usami ◽  
S. A. Salman ◽  
K. Kuroda ◽  
M. K. Gouda ◽  
A. Mahdy ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Nickel Nanoparticles ◽  
Raw Materials ◽  
Reduction Process ◽  
Electronic Configuration ◽  
Reduction Reaction ◽  
Cobalt Sulfate ◽  
Mixing Ratios ◽  
Phase Reduction ◽  
Cobalt Nickel

Cobalt-nickel nanoparticles (Co-Ni-NPs) show promising electrochemical performance in oxygen and hydrogen evolution reactions (OER and HER) due to their physicochemical properties such as electronic configuration and great electrochemical stability. Therefore, developing new economically and environmentally friendly methods of synthesizing Co-Ni-NPs has become a practical requirement. Co-Ni-NPs were produced by employing the liquid-phase reduction method. Nickel and cobalt sulfate solutions in hydrazine monohydrate with various mixing ratios were used as raw materials. Nickel plays an important role in the nucleation process via increasing the reduction reaction rate throughout the formation of Co-Ni-NPs. Furthermore, the acceleration of the Co-Ni-NPs formation process may be attributed to the partial dissolution of Ni(OH)2 in the presence of N2H4 and/or citrate-anions and the formation of the Ni-N2H4 or Ni-Cit complexes in contrast to Co(OH)2.

A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

2020 ◽  
Author(s):  
Travis Marshall-Roth ◽  
Nicole J. Libretto ◽  
Alexandra T. Wrobel ◽  
Kevin Anderton ◽  
Nathan D. Ricke ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Active Sites ◽  
Catalytic Properties ◽  
Reduction Reaction ◽  
Iron Phthalocyanine ◽  
Electrochemical Studies ◽  
Onset Potential ◽  
Nitrogen Doped Carbon ◽  
Iron Active Sites

Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum in fuel cells, but their active site structures are poorly understood. A leading postulate is that iron active sites in this class of materials exist in an Fe-N<sub>4</sub> pyridinic ligation environment. Yet, molecular Fe-based catalysts for the oxygen reduction reaction (ORR) generally feature pyrrolic coordination and pyridinic Fe-N<sub>4</sub> catalysts are, to the best of our knowledge, non-existent. We report the synthesis and characterization of a molecular pyridinic hexaazacyclophane macrocycle, (phen<sub>2</sub>N<sub>2</sub>)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for oxygen reduction to a prototypical Fe-N-C material, as well as iron phthalocyanine, (Pc)Fe, and iron octaethylporphyrin, (OEP)Fe, prototypical pyrrolic iron macrocycles. N 1s XPS signatures for coordinated N atoms in (phen<sub>2</sub>N<sub>2</sub>)Fe are positively shifted relative to (Pc)Fe and (OEP)Fe, and overlay with those of Fe-N-C. Likewise, spectroscopic XAS signatures of (phen<sub>2</sub>N<sub>2</sub>)Fe are distinct from those of both (Pc)Fe and (OEP)Fe, and are remarkably similar to those of Fe-N-C with compressed Fe–N bond lengths of 1.97 Å in (phen<sub>2</sub>N<sub>2</sub>)Fe that are close to the average 1.94 Å length in Fe-N-C. Electrochemical studies establish that both (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe have relatively high Fe(III/II) potentials at ~0.6 V, ~300 mV positive of (OEP)Fe. The ORR onset potential is found to directly correlate with the Fe(III/II) potential leading to a ~300 mV positive shift in the onset of ORR for (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe relative to (OEP)Fe. Consequently, the ORR onset for (phen<sub>2</sub>N<sub>2</sub>)Fe and (Pc)Fe is within 150 mV of Fe-N-C. Unlike (OEP)Fe and (Pc)Fe, (phen<sub>2</sub>N<sub>2</sub>)Fe displays excellent selectivity for 4-electron ORR with <4% maximum H<sub>2</sub>O<sub>2</sub> production, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data establish (phen<sub>2</sub>N<sub>2</sub>)Fe as a pyridinic iron macrocycle that effectively models Fe-N-C active sites, thereby providing a rich molecular platform for understanding this important class of catalytic materials.<p><b></b></p>

Novel Aqueous Fabrication and Characterization of Gold Coated Cobalt Nanoparticles

2016 ◽  
Vol 1 (2) ◽  
pp. 95-101
Author(s):  
Geoffrey N. Manani ◽  
Ryan T. Spidle ◽  
Anagh Bhaumik ◽  
Kartik Ghosh ◽  
Raja Ram Pandey ◽  
...  
Keyword(s):  
Cobalt Nanoparticles ◽  
Fabrication And Characterization

scholarly journals Characterization of Phosphate Coatings: Influence of the Acid Pickling Conditions

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1048
Author(s):  
Belén Díaz ◽  
X. Ramón Nóvoa ◽  
Carmen Pérez ◽  
Sheila Silva-Fernández
Keyword(s):  
Citric Acid ◽  
High Strength ◽  
Acid Pickling ◽  
Acid Cleaning ◽  
Inorganic Acids ◽  
Phosphate Coatings ◽  
Acid Bath ◽  
Coating Morphology ◽  
Coating Weight

This research emphasizes the importance of the acid cleaning prior to the phosphate development on high-strength steel rods. It compares the phosphate properties achieved after different acid-pickling conditions. The most common inorganic acids were considered in this study. Additionally, taking into account the environmental and safety concerns of these acids, the assessment of a less harmful organic acid is presented. This study revealed significant differences in the coating morphology and chemical composition whereas no great changes were found in terms of the coating weight or porosity. Thus, hydrochloric and sulfuric acid promote the growth of a Fe-enriched phosphate layer with a less conductive character that is not developed after the pickling with phosphoric acid. The phosphate developed after the citric acid pickling is comparable to that developed after the inorganic acids although with a porosity slightly higher. The temperature of the citric acid bath is an important parameter that affects to the phosphate appearance, composition, and porosity.

scholarly journals Structural Characterization of a Polysaccharide from Gastrodia elata and Its Bioactivity on Gut Microbiota

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4443
Author(s):  
Jiangyan Huo ◽  
Min Lei ◽  
Feifei Li ◽  
Jinjun Hou ◽  
Zijia Zhang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Citric Acid ◽  
Gut Microbiota ◽  
Structural Characterization ◽  
Hot Water ◽  
Nmr Analysis ◽  
Gastrodia Elata ◽  
Hot Water Extraction ◽  
Hydroxybenzyl Alcohol

A novel homogeneous polysaccharide named GEP-1 was isolated and purified from Gastrodia elata (G. elata) by hot-water extraction, ethanol precipitation, and membrane separator. GEP-1, which has a molecular weight of 20.1 kDa, contains a polysaccharide framework comprised of only glucose. Methylation and NMR analysis showed that GEP-1 contained 1,3,6-linked-α-Glcp, 1,4-linked-α-Glcp, 1,4-linked-β-Glcp and 1,4,6-linked-α-Glcp. Interestingly, GEP-1 contained citric acid and repeating p-hydroxybenzyl alcohol as one branch. Furthermore, a bioactivity test showed that GEP-1 could significantly promote the growth of Akkermansia muciniphila (A. muciniphila) and Lacticaseibacillus paracasei (L.paracasei) strains. These results implied that GEP-1 might be useful for human by modulating gut microbiota.

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