Size-induced structural transitions in the Cu-O and Ce-O systems

Palkar, V. R.; Ayyub, Pushan; Chattopadhyay, Soma; Multani, M.S.

doi:10.1103/physrevb.53.2167

Cited by 155 publications

(100 citation statements)

References 7 publications

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“…For the erroneous impact of the support (especially reducible metal oxides like ceria or zirconia, and partly ZnO) on the quantification of dispersion and passivation extent, we refer to Bartley et al [27]. Concerning the stability of Cu 2 O phases, Palkar et al [39] report that cubic Cu 2 O is more stable than monoclinic CuO at small crystallite sizes ( < 25 nm). This is related to the increasing ionic character of solids with decreasing particle size and is also dependent on calcination conditions.…”

Section: Characterizationmentioning

confidence: 97%

Remarks on the passivation of reduced Cu-, Ni-, Fe-, Co-based catalysts

Huber

Lögdberg

et al. 2006

Catal Lett

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Catalysts containing metals such as Cu, Ni, Fe, Co in their reduced state are often subjected to passivation procedures prior to characterization. Passivation with N 2 O or O 2 to create a protective oxide layer also results in a certain degree of sub-surface oxidation. The heat released during oxidation is a critical parameter. The extent of bulk oxidation depends on the type of oxidant as well as on the size of the metal particles, as shown for copper catalysts. The final, meta-stable passivation layer requires a certain thickness to sustain exposure to ambient atmosphere. The encapsulation of metal particles in carbon is an efficient method for preserving the metallic state, as demonstrated for metallic nickel and iron with carbon nanofibers. The use of passivated samples for characterization of the active, i.e., reduced, catalyst has limited value.

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Section: Characterizationmentioning

confidence: 97%

Remarks on the passivation of reduced Cu-, Ni-, Fe-, Co-based catalysts

Huber

Lögdberg

et al. 2006

Catal Lett

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“…Consequently, it was confirmed that Cu 2 O nanoparticles can be uniformly dispersed in the matrix, irrespective of initial amount of deposited Cu. Palkar et al has reported that a decrease in particle size (below 25 nm) is to favor the Cu 2 O phase over CuO due to increase in ionic character with decreasing particle size [18]. It seems thus likely that the particles in the present study are Cu 2 O (not CuO) because the particle size is almost below 10 nm.…”

Section: Methodsmentioning

confidence: 80%

Preparation of Cu 2O nanoparticles dispersed in NH 2-terminated polyethyleneoxide matrix

Yanagimoto

Akamatsu

Gotō

et al. 2001

The European Physical Journal D

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Small Copper (I) oxide, Cu2O, nanoparticles dispersed in diamine-terminated polyethyleneoxide (PEO-NH2) matrix have been successfully prepared by vacuum evaporation of copper onto the molten PEO-NH2. The obtained composite were characterized by TEM, electron diffraction, TG-DTA and FT-IR spectroscopy. The stable composite, in which the Cu2O nanoparticles are stabilized through interaction between NH2 chain end groups of PEO molecules and Cu2O nanoparticles was obtained when the samples were heat-treated at 110 • C. The mean size of the Cu2O nanoparticles increased from 2.5 to 3.5 nm in diameter upon increasing the amount of initial Cu deposition. The obtained composite material having a waxy texture was soluble in many solvents without aggregation and can be handled as a simple chemical compound for starting material in various applications.

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“…At 80 W, when the annealing time was increased from 5 to 15 minutes with an effluent temperature increased from 288 to 349°C (Table 1), the conversion of CuO into Cu 2 O increased. The previous study also demonstrated that Cu nanoparticles could be converted into Cu 2 O at a low temperature of 250°C [38]. However, the weak CuO peaks in the XRD patterns that were still found after modification for 15 min at either 60 W or 80 W should be caused by the thick CuO film (about 15 μm) that was prepared by the former thermal oxidation process, and led to no signal of Cu substrate (thickness of 1 mm) that can be identified.…”

Section: Cu 2 O Nanowires Produced By Rf Plasma Reductionmentioning

confidence: 88%

“…By the thermal method, the decomposition of CuO to Cu 2 O is difficult and needs to be conducted in an environment above 1100°C [37,38]. Hence, the CuO nanowires prepared at 500°C were reduced into Cu 2 O by reacting with N-containing energetic species produced by the RF plasma at a relatively low temperature (<350°C) with a short reaction time (5-15 min).…”

Section: Cu 2 O Nanowires Produced By Rf Plasma Reductionmentioning

confidence: 99%

“…However, due to the fact that the measurement of NO trace was difficult, the optical emission spectrum (OES) was used to identify the active species. The plasma diagnosis was obtained via observations of optical emission spectra with the main bands and peak positions listed in Table 4 [37][38][39][40][41][42].…”

Section: Cu 2 O Nanowires Produced By Mw Plasma Reductionmentioning

confidence: 99%

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Preparation of Cu2O nanowires by thermal oxidation-plasma reduction method

Chen

Kuo

et al. 2012

Appl. Phys. A

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Facial synthesis of cuprous oxide (Cu 2 O) nanowires by directly heating copper substrates is difficult; however, in this study, it was successfully done by thermal oxidation followed by a plasma reduction process. The preparation of CuO nanowires with an average diameter of 76.2 nm supported on the surface of copper substrate was conducted first in air at 500°C for 3 hrs, and then the CuO nanowires were reduced into Cu 2 O in 15 min using either radio frequency (RF) N 2 plasma or microwave (MW) N 2 plasma. The characteristics of CuO and Cu 2 O nanowires were analyzed using XRD, FE-SEM, and TEM. The results showed that Cu 2 O nanowires can be successfully reduced from CuO nanowires by a simple, promising, and fast nitrogen plasma process. Moreover, in RF plasma, narrower and longer Cu 2 O nanowires can be produced as compared to MW plasma, because energetic N-containing species can reduce the nanowires at a relatively lower temperature.

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Size-induced structural transitions in the Cu-O and Ce-O systems

Cited by 155 publications

References 7 publications

Remarks on the passivation of reduced Cu-, Ni-, Fe-, Co-based catalysts

Remarks on the passivation of reduced Cu-, Ni-, Fe-, Co-based catalysts

Preparation of Cu 2O nanoparticles dispersed in NH 2-terminated polyethyleneoxide matrix

Preparation of Cu2O nanowires by thermal oxidation-plasma reduction method

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