Electroless Deposition of Ferromagnetic Cobalt Nanoparticles in Propylene Glycol

Balela, Mary Donnabelle L.; Yagi, Shunsuke; Lockman, Zainovia; Aziz, Azizan; Amorsolo, Alberto V.; Matsubara, Eiichiro

doi:10.1149/1.3169776

Cited by 28 publications

(24 citation statements)

References 28 publications

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“…1(a) provide clear evidence of metallic Cu formation due to a peak associated with Cu(111) at 43.3°i n the Cu/Al 2 O 3 catalyst, but only weak diffraction peaks from the metals were seen for Ni/Al 2 O 3 and Co/Al 2 O 3 due to overlapping diffraction peaks with the support. 11,24,25 For the bimetallic Cu-Co and Cu-Ni catalysts, diffraction peaks were observed at 43.9°and 44°, respectively, which fall between the expected diffraction peaks of the pure metals, see Fig. 1(b).…”

Section: Resultsmentioning

confidence: 75%

Single-step catalytic conversion of furfural to 2-pentanol over bimetallic Co–Cu catalysts

et al. 2019

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Section: Resultsmentioning

confidence: 75%

Single-step catalytic conversion of furfural to 2-pentanol over bimetallic Co–Cu catalysts

et al. 2019

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“…This is consistent with the previous study that the major crystalline structure of Co is fcc in the nanoparticles, and this tendency becomes significant in the smaller particles. [12][13][14] In the XRD profiles in Fig. 3c and d, a very diffused peak exists at 55.5°.…”

Section: Resultsmentioning

confidence: 95%

“…The mean particle size of the Co nanoparticles decreases with an increase in the concentration of H 2 PtCl 6 , which shows that the nucleating agent apparently works as nuclei of the Co nanoparticles. 11,12 The smallest Co nanoparticles of 24 nm in diameter are obtained with the addition of 2.2 mM H 2 PtCl 6 . The relative standard deviations of the sample size are about 12-16%.…”

Section: Resultsmentioning

confidence: 99%

Room-Temperature Synthesis of Cobalt Nanoparticles by Electroless Deposition in Aqueous Solution

Balela

Yagi

Matsubara

2010

Electrochem. Solid-State Lett.

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Metallic Co nanoparticles of 24-110 nm diameters are prepared by electroless deposition ͑chemical reduction͒ in an aqueous solution at room temperature. The reduction process is monitored by an in situ measurement of a mixed potential. The mixed potential, which is above the redox potential of a Co͑II͒/Co redox pair, drops by the addition of the nucleating agent H 2 PtCl 6 and also decreases with an increase in the H 2 PtCl 6 concentration. Smaller Co nanoparticles are formed. In the smaller particle size, the fraction of the face-centered cubic Co phase increases, and the hexagonal close-packed Co phase decreases.Co nanoparticles have great scientific and technological importance due to their unique properties that are different from the bulk. 1-4 The formation of Co nanoparticles has been extensively studied over the years, leading to a wide variety of synthesis methods, such as thermal decomposition, micellar reduction, sonochemical reduction, and simple chemical ͑solution͒ reduction. 1-9 Most of the methods are conducted in an organic solvent at an elevated temperature because the fabrication of Co nanoparticles at room temperature is still challenging, specifically in an aqueous solution. This is due to the difficulty of formation of size-controlled Co nanoparticles without agglomeration and oxidation. The reducing agent, such as sodium borohydride, can reduce Co͑II͒ ions at room temperature. 3-5 However, the synthesized Co nanoparticles are usually polydispersed and amorphous containing boron. 3,4 In this article, we present a method of preparation of Co nanoparticles with diameters of 24-110 nm by electroless deposition ͑chemical reduction͒ with hydrazine monohydrate ͑N 2 H 4 ·H 2 O͒ as a reducing agent in an aqueous solution at room temperature. Chloroplatinic acid hexahydrate ͑H 2 PtCl 6 ·6H 2 O͒ is used as a nucleating agent. The effects of the nucleating agent on the particle morphology and deposition rates are studied by electron microscopy and in situ mixed potential measurements, respectively. ExperimentalAll chemical reagents were analytical grade ͑Nacalai Tesque͒. A Co͑II͒ aqueous solution was prepared by dissolving 0.01 mol Co͑II͒ acetate tetrahydrate ͓Co͑C 2 H 3 O 2 ͒ 2 ·4H 2 O͔ and 1.3 ϫ 10 −4 mol poly͑ethylene glycol͒ ͓H͑OCH 2 CH 2 ͒nOH, M w = 20,000͔ in 50 mL deoxygenated water. Then, 1 M sodium hydroxide ͑NaOH͒ aqueous solution of 25 mL was added to provide OH − ions. Next, 2.5 ϫ 10 -6 to 2.5 ϫ 10 −4 mol H 2 PtCl 6 ·6H 2 O in a propylene glycol ͑C 3 H 8 O 2 ͒ solution of 10 mL was added as the nucleating agent. The reducing agent solution was prepared by mixing 0.1 mol N 2 H 4 ·H 2 O in 25 mL deoxygenated C 3 H 8 O 2 . The N 2 H 4 ·H 2 O-C 3 H 8 O 2 solution was then added into the Co͑II͒ aqueous solution at room temperature, while the solution was continuously stirred and nitrogen gas ͑N 2 ͒ was bubbled at 50 mL/min. The pH value of the total solution was about 12. The total volume was 115 mL, and the final concentrations were 0.087 M Co͑II͒ acetate tetrahydrate, 1.1 mM poly͑eth-ylene glyco...

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“…Figure 1 shows the change in the mixed potentials during electroless deposition of 0.087 M Co(II) acetate in an aqueous solution with different concentrations of H 2 PtCl 6 . Based on thermodynamics, reduction of Co(II) ions occurs when the mixed potential is less than the oxidation-reduction potential of the Co(II)/Co redox pair [E Co(II)/Co = −0.615 V vs. SHE] (8)(9). Without H 2 PtCl 6 , the mixed potentials were fluctuated, and their average values in Fig.…”

Section: Methodsmentioning

confidence: 99%

Room-Temperature Synthesis of Cobalt Nanoparticles in Aqueous Solution

2010

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A fast low-cost approach to the fabrication of metallic cobalt (Co) nanoparticles is proposed. Metallic Co nanoparticles with mean diameters of 24−112 nm are synthesized by electroless deposition (chemical reduction) in an aqueous solution at room temperature. H 2 PtCl 6 and N 2 H 4 are used as a nucleating agent and a reductant, respectively. The Co(II) reduction rate and the mean particles size are strongly influenced by the concentration of the nucleating agent, which are observed by in situ mixed potential measurement and electron microscopy. The mixed potential shifts negatively with increasing H 2 PtCl 6 , which results to fast reduction of Co(II) ions. Small Co nanoparticles are thus formed.

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Electroless Deposition of Ferromagnetic Cobalt Nanoparticles in Propylene Glycol

Cited by 28 publications

References 28 publications

Single-step catalytic conversion of furfural to 2-pentanol over bimetallic Co–Cu catalysts

Single-step catalytic conversion of furfural to 2-pentanol over bimetallic Co–Cu catalysts

Room-Temperature Synthesis of Cobalt Nanoparticles by Electroless Deposition in Aqueous Solution

Room-Temperature Synthesis of Cobalt Nanoparticles in Aqueous Solution

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