Ultrafast Nanostructuring Oxidation of Crystallized Intermetallic ZrAu at 25 °C

Valmalette, Jean‐Christophe; Isa, M. Mohamad; Passard, and M.; Lomello-Tafin, Marc

doi:10.1021/cm011184z

Cited by 11 publications

(12 citation statements)

References 13 publications

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“…The extreme reactivity of the crystallised ZrAu alloy in air and at room temperature has been previously reported [1]. This process is really amazing because such reactivity in similar thermodynamic conditions has never been mentioned in any type of crystallised or amorphous alloys and because of plenty of questions raised by this phenomenon [2].…”

Section: Introductionmentioning

confidence: 73%

“…We had previously mentioned that slice surfaces exhibit a purple/gilded colour after few hours of air exposure [1] i.e. the formation of a thin film of Au/ZrO 2 nanoparticles is the first step of the oxidation mechanism.…”

Section: Discussionmentioning

confidence: 99%

“…This layer is composed of gold and zirconia nanoparticles [1]. After a few weeks under these thermodynamic conditions, samples are completely transformed into black powder (Fig.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Study of the nanostructuration of ZrAu alloy near the ambient temperature by X-ray diffraction and thermal analyses

Isa

Valmalette

Müller

et al. 2004

Journal of Alloys and Compounds

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Section: Introductionmentioning

confidence: 73%

Section: Discussionmentioning

confidence: 99%

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Study of the nanostructuration of ZrAu alloy near the ambient temperature by X-ray diffraction and thermal analyses

Isa

Valmalette

Müller

et al. 2004

Journal of Alloys and Compounds

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“…The oxidation of pure Zr is more facilitated as Zr is alloyed with gold. It should be noted that the intermetallic compound AuZr is easily oxidized even at room temperature [12,16]. Although the mechanism of the oxidation behavior of AuZr is fairly complex [16], gold atoms in this compound promote adsorption and diffusion of oxygen, i.e., gold acts as a catalyst in the oxidation process of AuZr.…”

Section: Methodsmentioning

confidence: 99%

“…Decreases of the oxidation temperature for AuZr 3 H x may be figured out as follows; the structure change of AuZr 3 by hydrogen absorption plays a crucial role in oxidation behavior and a part of hydrogen in AuZr 3 H x is somewhat responsible for the oxidation. Valmalette et al reported that moisture significantly increase in the oxidation rate of AuZr [16]. Consequently, the oxidation of AuZr 3 with hydrogen absorption has the beneficial effect of H 2 O formation on the oxidation of AuZr 3 .…”

Section: Methodsmentioning

confidence: 99%

Preparation of Nano-Composited Catalyst from the Bulk Intermetallic Compound AuZr3 with Hydrogen Absorption

et al. 2010

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Calcination-induced catalytic activity of CO oxidation reaction (CO ? 1/2O 2 ? CO 2 ) for an intermetallic, AuZr 3 and a hydride, AuZr 3 H x (x = 4.8) has been studied. The catalytic activities for both samples were originated from the formation of nano-gold particles and nano-crystalline ZrO 2 , result by oxidation upon calcination. Oxidation of the AuZr 3 H x occurred at lower temperature than the AuZr 3 , gave rise to the formation of more homogenous distribution and smaller sizes of nano-gold particles (*5 nm) on ZrO 2 , which were responsible for relatively high catalytic performance. This study provides the possibility of hydrogen absorption treatment being a beneficial process for obtaining nano-composite from intermetallic compounds for catalysts.

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In Situ Phase Separation of NiAu Alloy Nanoparticles for Preparing Highly Active Au/NiO CO Oxidation Catalysts

et al. 2008

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We report the synthesis of NiAu alloy nanoparticles (NPs) and their use in preparing Au/NiO CO oxidation catalysts. Because of the large differences in Ni and Au reduction potentials and the immiscibility of the two metals at low temperatures, [1,2] NiAu alloy NP colloids are inherently difficult to prepare by reducing metal salts with common reducing agents. This study describes the first solution-based synthesis of NiAu alloy NPs by way of a fast butyllithium reduction method. By supporting the particles on SiO 2 and subsequent conditioning, one obtains a NiO-stabilized Au NP catalyst that exhibits remarkable resistance to sintering and is highly active for CO oxidation. The active NiO-stabilized Au NP catalyst is prepared by in situ phase transformation of NiAu alloy NPs through an Au@Ni core-shell-like NP intermediate. In contrast, the corresponding NiO-free Au NPs prepared by an analogous method show negligible low-temperature catalytic activity and a high propensity for coalescence.The development of new bimetallic NP catalysts in various architectures (e.g. alloy, core-shell, aggregates) is receiving increased attention due to the need for more sophisticated, multifunctional catalysts in a variety of applications. [3][4][5][6][7] In comparison to monometallic systems, bimetallic catalysts have the potential advantages of bifunctional activity [8] (e.g. PtRu electrocatalysts), tunable non-native reactivities [5] (e.g. core-shell NPs), and stabilizing influences from a co-metal partner. A classic example of the later is to use certain metal oxides to modify "inactive" silica supports [9] to stabilize and activate small Au NPs for CO oxidation reactions. [10,11] To rationally advance the design of heterogeneous catalysts, systematic analyses of bimetallic architectures and the development of new synthetic methods to make multifunctional catalysts are needed. Herein, we report a new strategy to prepare oxide-stabilized noblemetal NP catalysts using a controlled stepwise phase-separation process of a bimetallic NP precursor. We demonstrate this strategy by making silica-supported NiO-stabilized Au CO oxidation catalysts using an in situ phase separation process of NiAu alloy NP precursor. Because silica is well known to be a poor support for stabilizing Au NPs in catalytic systems, it is an ideal support for evaluating effects of secondary metal oxide components.In the solid state, NiAu alloys can be prepared by high-temperature annealing. [1,2] However, this method produces large particles with small surface areas that limit their application in catalysis. The Ni-Au phase diagram [1,2] shows a solid-solution fcc alloy phase at high temperatures (> 740 8C for 1:1 alloy), but there is a large immiscibility region containing phase-separated fcc Au and fcc Ni at low temperatures. The low-temperature immiscibility of Ni and Au and the large discrepancy in reduction potentials complicate solution-based NiAu alloy preparations. In a previous report, we described a fast butyllithium reduction method for the preparatio...

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Ultrafast Nanostructuring Oxidation of Crystallized Intermetallic ZrAu at 25 °C

Cited by 11 publications

References 13 publications

Study of the nanostructuration of ZrAu alloy near the ambient temperature by X-ray diffraction and thermal analyses

Study of the nanostructuration of ZrAu alloy near the ambient temperature by X-ray diffraction and thermal analyses

Preparation of Nano-Composited Catalyst from the Bulk Intermetallic Compound AuZr3 with Hydrogen Absorption

In Situ Phase Separation of NiAu Alloy Nanoparticles for Preparing Highly Active Au/NiO CO Oxidation Catalysts

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