XAFS study on promoting effect of Au via NiO reduction in Au-Ni bimetallic clusters

Shirakawa, Shogo; Osaki, Mayuko; Nagai, Yasutaka; Nishimura, Yusaku; Dohmae, Kazuhiko; Matsumoto, Shinichi; Hirata, Hirohito

doi:10.1016/j.cattod.2016.05.019

Cited by 13 publications

(15 citation statements)

References 29 publications

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“…Note that this protocol was not followed in previous studies of this system. 12 , 13 , 17 Table 2 summarizes the resulting steady state reaction data. All catalysts exhibited low N 2 O formation at 550 °C, a temperature that falls within the typical operating window for such catalysts; 18 very conspicuously, the Au 25 Ni 75 and Au 50 Ni 50 compositions delivered much higher NO conversions than the others.…”

Section: Resultsmentioning

confidence: 99%

“… 12 Their subsequent in situ study of a single catalyst consisting of ∼ 1:1 Au–Ni bimetallic particles supported on silica confirmed the effect of Au addition, but left open a number of key questions, including the actual condition of catalyst before and after reaction, the nature of the Au–Ni interaction, its dependence on composition, and the identity of the catalytically active sites. 13 As the authors themselves concluded “ However, the nature of the active sites remains very complicated, and there is room for further investigation. ” The object of the present paper is to identify or clarify the key issues.…”

Section: Introductionmentioning

confidence: 99%

“…Experimentally, particular attention was given to the method of sample preparation and, especially, the oxidative pretreatment applied to remove extensive polymeric residues, whose presence can radically affect the nature of the working catalyst. It was found that the methods previously used for such catalysts (e.g., 300 °C in air) 13 are inadequate. Although the catalysts underwent some sintering as a result of calcination in air, they retained their bimetallic nature and were stable against further sintering during subsequent reduction and catalytic reaction.…”

Section: Introductionmentioning

confidence: 99%

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Comprehensive Experimental and Theoretical Study of the CO + NO Reaction Catalyzed by Au/Ni Nanoparticles

et al. 2019

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The catalytic and structural properties of five different nanoparticle catalysts with varying Au/Ni composition were studied by six different methods, including in situ X-ray absorption spectroscopy and density functional theory (DFT) calculations. The as-prepared materials contained substantial amounts of residual capping agent arising from the commonly used synthetic procedure. Thorough removal of this material by oxidation was essential for the acquisition of valid catalytic data. All catalysts were highly selective toward N 2 formation, with 50–50 Au:Ni material being best of all. In situ X-ray absorption near edge structure spectroscopy showed that although Au acted to moderate the oxidation state of Ni, there was no clear correlation between catalytic activity and nickel oxidation state. However, in situ extended X-ray absorption fine structure spectroscopy showed a good correlation between Au–Ni coordination number (highest for Ni 50 Au 50 ) and catalytic activity. Importantly, these measurements also demonstrated substantial and reversible Au/Ni intermixing as a function of temperature between 550 °C (reaction temperature) and 150 °C, underlining the importance of in situ methods to the correct interpretation of reaction data. DFT calculations on smooth, stepped, monometallic and bimetallic surfaces showed that N + N recombination rather than NO dissociation was always rate-determining and that the activation barrier to recombination reaction decreased with increased Au content, thus accounting for the experimental observations. Across the entire composition range, the oxidation state of Ni did not correlate with activity, in disagreement with earlier work, and theory showed that NiO itself should be catalytically inert. Au–Ni interactions were of paramount importance in promoting N + N recombination, the rate-limiting step.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comprehensive Experimental and Theoretical Study of the CO + NO Reaction Catalyzed by Au/Ni Nanoparticles

et al. 2019

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“…In addition, some research groups found the synergetic effect of gold and nickel [33,34]. For example, Shirakawa et al reported the gold atoms improve the release of oxygen from nickel atoms of NiO within cluster [33]. Thus, in this work, we tried to combine the effect of nickel on gold activity and the structure-activity relationship on WGS and CO oxidation reactions.…”

Section: Of 13mentioning

confidence: 99%

“…Our previous findings also indicated that ceria-supported gold catalyst is very active for both CO oxidation [21] and WGS [7] reactions. In addition, some research groups found the synergetic effect of gold and nickel [33,34]. For example, Shirakawa et al reported the gold atoms improve the release of oxygen from nickel atoms of NiO within cluster [33].…”

Section: Of 13mentioning

confidence: 99%

Effect of Nickel Oxide Doping to Ceria-Supported Gold Catalyst for CO Oxidation and Water-Gas Shift Reactions

et al. 2018

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Ceria-supported gold catalyst has drew much research interest owing to its high reactivity on CO oxidation and water-gas shift (WGS) reactions. However, till now, there were relatively limited studies on the effect of secondary metal/metal oxide component into gold-ceria system to enhance its catalytic performance. In this work, we synthetized the ceria supported gold-nickel samples via a deposition-precipitation method with the base of NaHCO3 to adjust final pH value of 8~9. We found that the addition of nickel oxide drove off the gold species from the stock solution during synthesis, and thus resulted in a dramatical decrease on doped Au concentration. No crystallized phases of gold and nickel were observed on the surface of ceria nanorods in both X-ray diffraction (XRD) and transmission electron microscopy (TEM). The valence of nickel was maintained as Ni2+ for all the measured samples by X-ray photoelectron spectroscopy (XPS), while gold was oxidized with the increased nickel amount after analysis of X-ray absorption near edge spectroscopy (XANES). The corresponding catalytic tests showed that with the introduction of nickel oxide, the activity of gold-ceria catalyst was promoted for the WGS reaction, but inhibited for the CO oxidation reaction.

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Tuning the electronic structure of AuNi homogeneous solid-solution alloy with positively charged Ni center for highly selective electrochemical CO2 reduction

Hao

Zhu

et al. 2021

Chemical Engineering Journal

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XAFS study on promoting effect of Au via NiO reduction in Au-Ni bimetallic clusters

Cited by 13 publications

References 29 publications

Comprehensive Experimental and Theoretical Study of the CO + NO Reaction Catalyzed by Au/Ni Nanoparticles

Comprehensive Experimental and Theoretical Study of the CO + NO Reaction Catalyzed by Au/Ni Nanoparticles

Effect of Nickel Oxide Doping to Ceria-Supported Gold Catalyst for CO Oxidation and Water-Gas Shift Reactions

Tuning the electronic structure of AuNi homogeneous solid-solution alloy with positively charged Ni center for highly selective electrochemical CO2 reduction

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