Catalytic Activity of Mono- and Bi-Metallic Nanoparticles Synthesized via Microemulsions

König, Ramona Y.G.; Schwarze, Michael; Schomäcker, Reinhard; Stubenrauch, Cosima

doi:10.3390/catal4030256

Cited by 26 publications

(22 citation statements)

References 36 publications

(68 reference statements)

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“…A more flexible surfactant film allows a faster material exchange [101] and, as a result, the difference between reduction rates is minimized, giving rise to a higher degree of mix [72]. This outcome can be clearly established from Table 1, by focusing our attention on nanoparticles prepared using a very flexible film, such as in a water/CTAB/isooctane/n-butanol microemulsion (see experiments number 15,25,28). All…”

Section: Keeping the Pair Of Metals Fixedmentioning

confidence: 93%

“…The presence of a second metal in a bimetallic nanoparticle not only reduces the cost as some noble metal that is substituted by a non-noble one, but also modifies the interactions between atoms giving rise to changes in the structure and surface. The electron interactions between two metal atoms, which are electron-rich, just as the heterometallic bonding interactions change the surface electronic properties of the nanoparticles [12][13][14][15][16][17][18][19]. As a rule, the catalytic behaviour is usually enhanced on bimetallic nanoparticles as compared to monometallic nanoparticles [3,7,[13][14][15][17][18][19][20][21] even at low Rai et al [46] suggest that the synergic cooperation between the two metals is more noticeable in alloyed nanoparticles, due to the higher probability of metal-metal interactions in comparison to core-shell ones.…”

Section: Bimetallic Nanoparticles As Catalystsmentioning

confidence: 99%

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On Metal Segregation of Bimetallic Nanocatalysts Prepared by a One-Pot Method in Microemulsions

2017

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A comparative study on different bimetallic nanocatalysts prepared from microemulsions using a one-pot method has been carried out. The analysis of experimental observations, complemented by simulation studies, provides detailed insight into the factors affecting nanoparticle architecture: (1) The metal segregation in a bimetallic nanocatalysts is the result of the combination of three main kinetic parameters: the reduction rate of metal precursors (related to reduction standard potentials), the material intermicellar exchange rate (determined by microemulsion composition), and the metal precursors concentration; (2) A minimum difference between the reduction standard potentials of the two metals of 0.20 V is needed to obtain a core-shell structure. For values ∆ε 0 smaller than 0.20 V the obtaining of alloys cannot be avoided, neither by changing the microemulsion nor by increasing metal concentration; (3) As a rule, the higher the film flexibility around the micelles, the higher the degree of mixture in the nanocatalyst; (4) A minimum concentration of metal precursors is required to get a core-shell structure. This minimum concentration depends on the microemulsion flexibility and on the difference in reduction rates.

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Section: Keeping the Pair Of Metals Fixedmentioning

confidence: 93%

Section: Bimetallic Nanoparticles As Catalystsmentioning

confidence: 99%

On Metal Segregation of Bimetallic Nanocatalysts Prepared by a One-Pot Method in Microemulsions

2017

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“…A synthesis procedure based on water-in-oil ME for mono (Pt) and bimetallic (PtBi, PtPb) nanoparticles is reported in the article by König et al [29]; furthermore, the catalytic activity was also reported [17]. As the authors concluded, bimetallic nanoparticles could be obtained, which consist of a mixture of different phases; the composition of the bimetallic particles was varied as a function of the metal salt ratio and the amount of reducing agent.…”

Section: The Present Issuementioning

confidence: 99%

Synthesis of Nanostructured Catalytic Materials from Microemulsions

Sánchez-Domínguez

Boutonnet

2015

Catalysts

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BackgroundSince the 1980s [1,2], colloidal systems such as microemulsions (ME) have been widely investigated, especially for the synthesis of nanomaterials for various applications. In the field of catalysis, nanoparticles of noble metal or metal oxides, responsible for the catalytic activity and selectivity, are usually involved in the composition of the catalytic material [3]. A catalyst normally consists of metal nanoparticles deposited onto a carrier such as silica or alumina. Ideally, the nanoparticles will present a highly active surface area due to high metal dispersion. In addition, the surface structure of the nanoparticles, which depends on their size and shape, are related to the selectivity of the catalysts, for instance this is important in the case of alkane isomerization, which is a structure sensitive reaction [4].Depending of the size, the nanoparticles will contain various defects, which will correspond to catalytic sites with different selectivities and activities. These active sites correspond to groups of metal atoms placed on the edges, corners, and terraces structures at the surfaces of the metal nanoparticles. These metal atoms will have different coordination states and present different electronic effects, which will consequently result in different catalytic activity and selectivity. This is the reason why the preparation of nanoparticles with well-defined particle size is still of great interest in the field of catalysis. If one is able to obtain well-defined metal nanoparticles, it will be possible to relate the selectivity and activity of the reaction to some specific size and consequently to have a better understanding of the catalytic reaction mechanism. Consequently, by using a well-designed nanomaterial as catalyst, it will be possible to predict its properties regarding its catalytic activity and selectivity.During these last years, it has been shown that nanomaterials obtained from ME present specific properties, especially regarding the catalytic selectivity compared to catalysts prepared from traditional methods. Several catalytic processes have been investigated using these types of catalysts, i.e., high temperature catalytic combustion of methane, electro-catalyst for hydrogen production from methanol, production of polyalcohols from synthesis gas, Diesel production from synthesis gas via Fisher-Tropsch and hydrocracking of waxes, etc. [3][4][5][6][7][8][9][10][11]. These very different processes are associated to a great range of catalytic materials. The microemulsion method, based on water-in-oil, oil-in-water and bicontinuous ME, has shown to be suitable for the preparation of all these different types of materials [12][13][14][15][16][17][18][19][20][21][22].Even though a few valuable efforts were previously done to understand the formation of nanomaterials in ME systems [23][24][25], comprehensive research in this area is still needed to clarify this process, in order to reach a better control of nanoparticle characteristics and to understand why the formed nanopartic...

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“…Apart from biological conversion, p ‐NP can be oxidized via chemical treatment with oxidizing agents such as hydrogen peroxide or ozone among others. Anaerobic biological degradation or catalytic reduction (eg, with the use of nanoparticles) leads in general to formation of 4‐aminophenol . Aqueous photolysis of nitrophenols by solar ultraviolet (UV) radiation proceeding via radical formation results in release of nitro group in the form of nitrous acid …”

Section: Introductionmentioning

confidence: 99%

Beyond esterase‐like activity of serum albumin. Histidine‐(nitro)phenol radical formation in conversion cascade of p‐nitrophenyl acetate and the role of infrared light

Kowacz

Warszyński

2019

J of Molecular Recognition

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Serum albumin, recognized mainly for its capacity to act as a carrier protein for many compounds, can also actively transform some organic molecules. As a starting point in this study, we consider esterase‐like activity of bovine serum albumin (BSA) toward p‐nitrophenyl acetate (p‐NPA). Our results reveal that the reaction goes beyond ester hydrolysis step. In fact, the transformation product, p‐nitrophenol (p‐NP), becomes a substrate for further reaction with BSA in which its nitro group in subtracted and released in the form of HNO2. Spectral data indicate that this cascade of events proceeds through formation of phenoxyl radical via proton‐coupled electron transport (PCET) between OH group of p‐NP and imidazole ring of histidine from the protein. Furthermore, the effect of application of electromagnetic radiation in the infrared range suggests that this remote physical trigger can support interactions based on PCET mechanism by acting on polarization and mutual alignment of water dipoles serving as effective water wires.

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Catalytic Activity of Mono- and Bi-Metallic Nanoparticles Synthesized via Microemulsions

Cited by 26 publications

References 36 publications

On Metal Segregation of Bimetallic Nanocatalysts Prepared by a One-Pot Method in Microemulsions

On Metal Segregation of Bimetallic Nanocatalysts Prepared by a One-Pot Method in Microemulsions

Synthesis of Nanostructured Catalytic Materials from Microemulsions

Beyond esterase‐like activity of serum albumin. Histidine‐(nitro)phenol radical formation in conversion cascade of p‐nitrophenyl acetate and the role of infrared light

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