New Highly Mixed Phases in Ball-Milled Cu/ZnO Catalysts as Established by EXAFS and XANES

Grandjean, D.; Castricum, H.L.; Heuvel, Robert H. H. van den; Weckhuysen, Bert M.

doi:10.1063/1.2644615

Cited by 6 publications

(6 citation statements)

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“…In addition, CuO can be discarded by the absence of a pre-edge peak at $8978 eV, which is a known spectral feature corresponding to Cu 1s-3d transitions of divalent copper compounds since there is no 3d hole in Cu(0) and Cu(1þ). [31,32] This is in good accordance with GIXRD results shown in Figure 1(a), which showed the absence of peaks for the CuO phase (JCPDS card 00-048-1548). In the case of the films with lower Cu content, the line shapes of the Cu-K spectra remained unchanged.…”

Section: Effect Of Annealing On the A-c Matrix: C K-edge Xanessupporting

confidence: 90%

“…This suggests an increasing metallic copper environment for the Cu absorber as the average Cu content increases. On the contrary, the line shape of the lowest content film exhibits some features of CuO: [31,32] a marked absorption drop after the main XANES feature and an absorption rise at high energy. These observations suggest an oxidation of the surface of the Cu aggregates whose contribution to the XANES signal decreases with the aggregates diameter.…”

Section: Effect Of Annealing On Nanocomposite Properties: Conductivitmentioning

confidence: 99%

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Impact of Annealing on the Conductivity of Amorphous Carbon Films Incorporating Copper and Gold Nanoparticles Deposited by Pulsed Dual Cathodic Arc

Endrino

Horwat

Anders

et al. 2009

Plasma Processes & Polymers

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The influence of annealing in argon at 300 °C on the conductivity, phase stability and electronic structure of hydrogen‐free amorphous carbon (a‐C) films containing copper (a‐C:Cu) and gold (a‐C:Au) nanoclusters was investigated. The motivation of this work is twofold: (1) to study the thermal stability of a‐C:Cu and a‐C:Au films and (2) to point out the relevance of X‐ray absorption near edge structure (XANES) technique to study the structural evolution of metal‐doped a‐C nanocomposites. The films were produced at room temperature using a selective‐bias pulsed dual‐cathode arc deposition technique. Compositional analysis was performed with secondary neutral mass spectroscopy whereas grazing incidence X‐ray diffraction (GIXRD) was used to monitor phase transformation and identify the dispersion or agglomeration of the crystallites within the carbon matrix. XANES spectra at the C‐K was used to investigate the effect of annealing in argon on the electronic structure of the a‐C matrix, while Cu K and Au L‐edges were investigated on a‐C:Cu and a‐C:Au samples, respectively, to study the nanocluster evolution. XANES showed that the a‐C host matrix increased its graphitic character and that stress was relieved upon annealing. No relevant changes were observed in the Au arrangements in a‐C:Au films. In the case of the a‐C:Cu samples, the Cu‐K XANES spectra indicated the formation of Cu2O crystals which correlated well with GIXRD spectra and the decrease in conductivity.

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Section: Effect Of Annealing On the A-c Matrix: C K-edge Xanessupporting

confidence: 90%

Section: Effect Of Annealing On Nanocomposite Properties: Conductivitmentioning

confidence: 99%

Impact of Annealing on the Conductivity of Amorphous Carbon Films Incorporating Copper and Gold Nanoparticles Deposited by Pulsed Dual Cathodic Arc

Endrino

Horwat

Anders

et al. 2009

Plasma Processes & Polymers

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“…The local environmental differences between Co, Ni, Cu, and Zn in J14 is made clearer by taking the Fourier transform (FT) of each k 2 χ( k ) using a Hanning window range of k ≈3.25‐11.9 Å −1 to obtain the real space function χ( R ), shown in Figure B. Overall, each χ( R ) is consistent with a typical metal‐oxide system . The first large peak, between 1‐2 Å corresponds to scattering between the absorber and first nearest‐neighbor oxygen atoms.…”

Section: Resultsmentioning

confidence: 96%

“…Overall, each v(R) is consistent with a typical metal-oxide system. [12][13][14] The first large peak, between 1-2 A corresponds to scattering between the absorber and first nearest-neighbor oxygen atoms. The second peak, between 2-3 A, is produced by scattering between the absorber and the second nearest neighbor shell, which is populated by metal atoms.…”

Section: Methodsmentioning

confidence: 99%

Local structure of the Mg_xNi_xCo_xCu_xZn_xO(x=0.2) entropy‐stabilized oxide: An EXAFS study

et al. 2017

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Entropy‐stabilized oxides (ESOs) provide an alternative route to novel materials discovery and synthesis. It is, however, a challenge to demonstrate that the constituent elements in an entropy‐stabilized crystal are homogeneously and randomly dispersed among a particular sublattice, resulting in a true solid solution with no evidence of local order or clustering. In this work, we present the application and analysis of extended X‐ray absorption fine structure (EXAFS) on the prototype ESO composition MgxNixCoxCuxZnxO (x=0.2). In so doing, we can quantify the local atomic structure on an element‐by‐element basis. We conclude that local bond lengths between metal and oxygen vary around each absorbing cation, with notable distortion around the Cu–O polyhedra. By the second near neighbor (i.e., the cation‐cation pair), interatomic distances are uniform to the extent that the collected data can resolve. Crystal models that best fit the experimental scattering data include cations that are distributed randomly on an FCC sublattice with minimal positional disorder, with an interleaved FCC anion sublattice with oxygen ions displaced from the ideal locations to accommodate the distortions in the cation polyhedra. Density functional theory calculations of the ESO system yield a significant broadening in the positional distribution for the oxygen sublattice compared to that for the cation sublattice for all peaks, showing consistency with the conclusion from the experimental data that the distortion from an ideal rock salt structure occurs primarily through disorder in the oxygen sublattice.

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“…5). 27 During the milling of copper oxides and ZnO mixtures in CO 2 , the corresponding carbonates were observed as intermediates, which resulted in intimate Cu-Zn mixtures upon decomposition. Recently, a planetary ball mill method has also been used for the preparation of SRM Cu/Al 2 O 3 catalysts using a mixture of CuO and Al.…”

Section: Supported Metal Nanoparticlesmentioning

confidence: 99%

Mechanochemical synthesis of advanced nanomaterials for catalytic applications

et al. 2015

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Mechanochemical synthesis emerged as the most advantageous, environmentally sound alternative to traditional routes for nanomaterials preparation with outstanding properties for advanced applications. Featuring simplicity, high reproducibility, mild/short reaction conditions and often solvent-free condition (dry milling), mechanochemistry can offer remarkable possibilities in the development of advanced catalytically active materials. The proposed contribution has been aimed to provide a brief account of remarkable recent findings and advances in the mechanochemical synthesis of solid phase advanced catalysts as opposed to conventional systems. The role of mechanical energy in the synthesis of solid catalysts and their application is critically discussed as well as the influence of the synthesis procedure on the physicochemical properties and the efficiency of synthesized catalysts is studied. The main purpose of this feature article is to highlight the possibilities of mechanochemical protocols in (nano)materials engineering for catalytic applications.

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New Highly Mixed Phases in Ball-Milled Cu/ZnO Catalysts as Established by EXAFS and XANES

Abstract: Abstract. AnXAFS investigation at both the

Cited by 6 publications

References 3 publications

Impact of Annealing on the Conductivity of Amorphous Carbon Films Incorporating Copper and Gold Nanoparticles Deposited by Pulsed Dual Cathodic Arc

Impact of Annealing on the Conductivity of Amorphous Carbon Films Incorporating Copper and Gold Nanoparticles Deposited by Pulsed Dual Cathodic Arc

Local structure of the Mg_xNi_xCo_xCu_xZn_xO(x=0.2) entropy‐stabilized oxide: An EXAFS study

Mechanochemical synthesis of advanced nanomaterials for catalytic applications

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New Highly Mixed Phases in Ball-Milled Cu/ZnO Catalysts as Established by EXAFS and XANES

Abstract: Abstract. AnXAFS investigation at both the

Cited by 6 publications

References 3 publications

Impact of Annealing on the Conductivity of Amorphous Carbon Films Incorporating Copper and Gold Nanoparticles Deposited by Pulsed Dual Cathodic Arc

Impact of Annealing on the Conductivity of Amorphous Carbon Films Incorporating Copper and Gold Nanoparticles Deposited by Pulsed Dual Cathodic Arc

Local structure of the MgxNixCoxCuxZnxO(x=0.2) entropy‐stabilized oxide: An EXAFS study

Mechanochemical synthesis of advanced nanomaterials for catalytic applications

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Local structure of the Mg_xNi_xCo_xCu_xZn_xO(x=0.2) entropy‐stabilized oxide: An EXAFS study