Topical Collection "Gold Catalysts"

Editors

Collection Editor
Dr. Leonarda F. Liotta

Institute of Nanostructured Materials, Palermo Research Division, CNR - ISMN, via Ugo La Malfa 153, 90146 Palermo, Italy
Website | E-Mail
Phone: +39 091 6809371
Fax: +39 091 6809399
Interests: synthesis; characterization and structure-activity relationship of supported noble metal (Pt,Pd,Au) for oxidation reactions; metal-support interaction in gold catalysts for low-temperature CO and VOCs oxidation; use of gold for hydrogen purification by selective oxidation of carbon monoxide (PROX); development of Pd and Au catalysts for abatement at low temperature of VOCs and methane emitted by mobile sources; synthesis and characterization of bimetallic Ni-Au catalysts for hydrocarbon steam reforming reaction and syngas production; optimization of Co-based catalysts composition and preparation method for Fischer-Tropsch synthesis
Collection Editor
Prof. Dr. Salvatore Scirè

Department of Chemical Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy
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Phone: +39 095 7385112
Fax: +39 095 580138
Interests: synthesis and catalytic activity measurements of supported catalysts; physico-chemical characterization of supported metal catalysts; catalysts for environmental protection; catalysts in the petrochemical industry and refinery; catalysts for energy production; gold based mono and bimetallic catalysts; gold-based catalysts for sensors and pollution control devices; low temperature combustion of VOCs; photocatalytic oxidation and water splitting; hydrogen on demand production; hydrogen purification for fuel cell applications

Topical Collection Information

Dear Colleagues,

Two Special Issues on gold catalysts, namely “Gold Catalysts“ and “New Trends in Gold Catalysts“, were successfully closed on 30 September 2011 and 15 June 2013, respectively, with a total of 24 papers published in Catalysts. These Special Issues had great success, and many of the papers received citations and reviews. Considering that the interest in the catalysis of gold is still continuously growing, with unresolved questions and new fields of applications, the Editorial Board of Catalysts decided to set this topic as a Topical Collection in the journal and invited us to lead this program. A Topical Collection functions the same way as a Special Issue but without a submission deadline within the next three years. During this period, authors will have the opportunity to contribute their excellent works on this key topic.

We thus invite all researchers working in the field of gold catalysts to submit high quality papers in this area, and also to serve as scholars in this field.

The topics of the Topical Collection include, but are not limited to:

  • recent progress and novel trends in the fields of gold catalysts ranging from the basic research and characterization (TEM, XPS, EXAFS, XRD, FT-IR) studies to the development of new gold catalyst formulations of environmental importance and industrial applications.
  • gold based bimetallic catalysts: synthesis, characterization and structure-activity relationship of supported mono and bi-metallic (Au-M) catalysts for oxidation and hydrogenation reactions;
  • investigations on the role of preparation method and pretreatment conditions on the performance of gold catalysts;
  • investigations on the durability of Au/metal oxide catalysts under reaction conditions;
  • metal-support interaction in gold catalysts for low-temperature CO, VOCs and soot oxidation;
  • use of gold for hydrogen purification by selective oxidation of carbon monoxide (PROX) and for hydrogen production (WGSR);
  • development and optimization of Au catalysts for selective oxidations and hydrogenations;
  • effects of support composition and oxygen vacancies content on gold activity and selectivity;
  • polymer supported gold catalysts
  • Au-based catalysts for sensors and pollution control devices;
  • Au catalysts for photocatalytic applications.

Dr. Leonarda Liotta
Prof. Dr. Salvatore Scirè
Collection Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the collection website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed open access monthly journal published by MDPI.

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Keywords

  • Preparation methods
  • Au oxidation state
  • Au-support interaction
  • Structural and electronic characterization
  • CO oxidation and PROX
  • Reduction of NOx and COx
  • Selective hydrogenation and oxidation
  • VOC and soot oxidation
  • Hydrodechlorination reactions
  • Stability under reaction conditions: Effect of CO2 and water added to the gas feed
  • Au-based photocatalysts

Related Special Issues

Published Papers (32 papers)

2018

Jump to: 2017, 2016, 2014, 2013, 2012, 2011

Open AccessArticle Selective Hydrogenation of Cinnamaldehyde Catalyzed by ZnO-Fe2O3 Mixed Oxide Supported Gold Nanocatalysts
Catalysts 2018, 8(2), 60; https://doi.org/10.3390/catal8020060
Received: 18 December 2017 / Revised: 24 January 2018 / Accepted: 31 January 2018 / Published: 3 February 2018
PDF Full-text (3222 KB) | HTML Full-text | XML Full-text
Abstract
ZnO-Fe2O3 mixed oxides and supported gold nanocatalysts were prepared by using coprecipitation and deposition–precipitation methods, respectively. Cinnamaldehyde hydrogenation over various ZnO-Fe2O3 mixed oxides supported gold nanocatalysts have been investigated at 140 °C and a hydrogen pressure of
[...] Read more.
ZnO-Fe2O3 mixed oxides and supported gold nanocatalysts were prepared by using coprecipitation and deposition–precipitation methods, respectively. Cinnamaldehyde hydrogenation over various ZnO-Fe2O3 mixed oxides supported gold nanocatalysts have been investigated at 140 °C and a hydrogen pressure of 1.0 MPa. The molar ratio of Fe to Zn was found to greatly affect the selective hydrogenation catalytic activity of ZnO-Fe2O3 mixed oxide supported gold nanocatalysts. Among these supported gold nanocatalysts in this work, Au/Zn0.7Fe0.3Ox (Au loading of 1.74 wt %) exhibited the highest conversion of cinnamaldehyde and high selectivity to cinnamal alcohol. The excellent catalytic activity of Au/Zn0.7Fe0.3Ox was tightly associated with a large surface area, small gold nanoparticles, and good H2 dissociation ability at low temperature. Full article
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2017

Jump to: 2018, 2016, 2014, 2013, 2012, 2011

Open AccessFeature PaperReview Dynamic Processes on Gold-Based Catalysts Followed by Environmental Microscopies
Catalysts 2017, 7(5), 134; https://doi.org/10.3390/catal7050134
Received: 30 March 2017 / Revised: 19 April 2017 / Accepted: 20 April 2017 / Published: 1 May 2017
Cited by 4 | PDF Full-text (16832 KB) | HTML Full-text | XML Full-text
Abstract
Since the early discovery of the catalytic activity of gold at low temperature, there has been a growing interest in Au and Au-based catalysis for a new class of applications. The complexity of the catalysts currently used ranges from single crystal to 3D
[...] Read more.
Since the early discovery of the catalytic activity of gold at low temperature, there has been a growing interest in Au and Au-based catalysis for a new class of applications. The complexity of the catalysts currently used ranges from single crystal to 3D structured materials. To improve the efficiency of such catalysts, a better understanding of the catalytic process is required, from both the kinetic and material viewpoints. The understanding of such processes can be achieved using environmental imaging techniques allowing the observation of catalytic processes under reaction conditions, so as to study the systems in conditions as close as possible to industrial conditions. This review focuses on the description of catalytic processes occurring on Au-based catalysts with selected in situ imaging techniques, i.e., PEEM/LEEM, FIM/FEM and E-TEM, allowing a wide range of pressure and material complexity to be covered. These techniques, among others, are applied to unravel the presence of spatiotemporal behaviours, study mass transport and phase separation, determine activation energies of elementary steps, observe the morphological changes of supported nanoparticles, and finally correlate the surface composition with the catalytic reactivity. Full article
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2016

Jump to: 2018, 2017, 2014, 2013, 2012, 2011

Open AccessArticle Au Capping Agent Removal Using Plasma at Mild Temperature
Catalysts 2016, 6(11), 179; https://doi.org/10.3390/catal6110179
Received: 15 September 2016 / Revised: 20 October 2016 / Accepted: 1 November 2016 / Published: 17 November 2016
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Abstract
To prevent sintering, ozone treatment at mild temperature is used to remove the capping agent from supported Au nanoparticles. The Au nanoparticles are first synthesized as a colloidal solution and then supported on alumina. Fourier Transform Infra Red (FTIR) shows the capping agent
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To prevent sintering, ozone treatment at mild temperature is used to remove the capping agent from supported Au nanoparticles. The Au nanoparticles are first synthesized as a colloidal solution and then supported on alumina. Fourier Transform Infra Red (FTIR) shows the capping agent is removed completely. Transmission Electron Microscopy (TEM) and catalytic test reactions show the Au does not sinter significantly upon low temperature ozone treatment. Full article
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Open AccessFeature PaperReview Au/CeO2 Catalysts: Structure and CO Oxidation Activity
Catalysts 2016, 6(10), 158; https://doi.org/10.3390/catal6100158
Received: 6 September 2016 / Revised: 3 October 2016 / Accepted: 11 October 2016 / Published: 18 October 2016
Cited by 13 | PDF Full-text (3283 KB) | HTML Full-text | XML Full-text
Abstract
In this comprehensive review, the main aspects of using Au/CeO2 catalysts in oxidation reactions are considered. The influence of the preparation methods and synthetic parameters, as well as the characteristics of the ceria support (presence of doping cations, oxygen vacancies concentration, surface
[...] Read more.
In this comprehensive review, the main aspects of using Au/CeO2 catalysts in oxidation reactions are considered. The influence of the preparation methods and synthetic parameters, as well as the characteristics of the ceria support (presence of doping cations, oxygen vacancies concentration, surface area, redox properties, etc.) in the dispersion and chemical state of gold are revised. The proposed review provides a detailed analysis of the literature data concerning the state of the art and the applications of gold–ceria systems in oxidation reactions. Full article
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Open AccessFeature PaperArticle Au/TiO2-CeO2 Catalysts for Photocatalytic Water Splitting and VOCs Oxidation Reactions
Catalysts 2016, 6(8), 121; https://doi.org/10.3390/catal6080121
Received: 1 July 2016 / Revised: 3 August 2016 / Accepted: 4 August 2016 / Published: 10 August 2016
Cited by 12 | PDF Full-text (6554 KB) | HTML Full-text | XML Full-text
Abstract
Photocatalytic water splitting for H2 production and photocatalytic oxidation of 2-propanol, an example of volatile organic compounds, were investigated over TiO2 catalysts loaded with gold and/or ceria. In the water splitting reaction the presence of gold only slightly affected the performance
[...] Read more.
Photocatalytic water splitting for H2 production and photocatalytic oxidation of 2-propanol, an example of volatile organic compounds, were investigated over TiO2 catalysts loaded with gold and/or ceria. In the water splitting reaction the presence of gold only slightly affected the performance of TiO2 whereas the presence of CeO2 had a more remarkable positive effect. In the 2-propanol oxidation Au/TiO2 was the most active sample in terms of alcohol conversion whereas Au/TiO2-CeO2 exhibited the highest CO2 yield. On the basis of characterization experiments (X-Ray Diffraction (XRD), Energy Dispersive X-ray Analysis EDX, surface area measurements, Diffuse Reflectance Spectroscopy (DRS) and Raman spectroscopy), it was suggested that the interaction of Au with TiO2 causes an increase in the charge separation between the photo-excited electron/hole pairs, leading to an enhanced photocatalytic activity (to acetone over Au/TiO2 and to CO2 over Au/TiO2-CeO2), whereas the presence of ceria, acting as a hole trap, positively mainly affects the formation of hydrogen by water splitting. Full article
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Open AccessFeature PaperReview Biomass Derived Chemicals: Furfural Oxidative Esterification to Methyl-2-furoate over Gold Catalysts
Catalysts 2016, 6(7), 107; https://doi.org/10.3390/catal6070107
Received: 16 March 2016 / Revised: 13 July 2016 / Accepted: 14 July 2016 / Published: 20 July 2016
Cited by 6 | PDF Full-text (4525 KB) | HTML Full-text | XML Full-text
Abstract
The use of heterogeneous catalysis to upgrade biomass wastes coming from lignocellulose into higher value-added chemicals is one of the most explored subjects in the prospective vision of bio-refinery. In this frame, a lot of interest has been driven towards biomass-derived building block
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The use of heterogeneous catalysis to upgrade biomass wastes coming from lignocellulose into higher value-added chemicals is one of the most explored subjects in the prospective vision of bio-refinery. In this frame, a lot of interest has been driven towards biomass-derived building block molecules, such as furfural. Gold supported catalysts have been successfully proven to be highly active and selective in the furfural oxidative esterification to methyl-2-furoate under mild conditions by employing oxygen as benign oxidant. Particular attention has been given to the studies in which the reaction occurs even without base as co-catalyst, which would lead to a more green and economically advantageous process. The Au catalysts are also stable and quite easily recovered and represent a feasible and promising route to efficiently convert furfural to methyl-2-furoate to be scaled up at industrial level. Full article
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Open AccessFeature PaperArticle Gold Catalysts on Y-Doped Ceria Supports for Complete Benzene Oxidation
Catalysts 2016, 6(7), 99; https://doi.org/10.3390/catal6070099
Received: 14 May 2016 / Revised: 28 June 2016 / Accepted: 1 July 2016 / Published: 8 July 2016
Cited by 2 | PDF Full-text (2911 KB) | HTML Full-text | XML Full-text
Abstract
Gold (3 wt. %) catalysts on Y-doped (1, 2.5, 5 and 7.5 wt. % Y2O3) ceria supports prepared by coprecipitation (CP) or impregnation (IM) were studied in complete benzene oxidation (CBO). A low-extent Y modification was chosen to avoid
[...] Read more.
Gold (3 wt. %) catalysts on Y-doped (1, 2.5, 5 and 7.5 wt. % Y2O3) ceria supports prepared by coprecipitation (CP) or impregnation (IM) were studied in complete benzene oxidation (CBO). A low-extent Y modification was chosen to avoid ordering of oxygen vacancies. The samples were characterized by XRD, TGA, XPS and TPR techniques. A positive role of air pretreatment at 350 °C as compared to 200 °C was established for all Y-containing catalysts and it was explained by cleaning the active sites from carbonates. The oxygen supply cannot be considered as a limiting step for benzene oxidation except for the high 7.5%-doped samples, as suggested by TGA and TPR data. On the basis of XPS results of fresh and used in CBO catalysts, the presence of cationic gold species does not seem important for high CBO activity. The gold catalyst on an IM support with 1% Y-doping exhibited the best performance. A 100% benzene conversion was achieved only over this catalyst and Au/ceria, while it was not reached even at 300 °C over all other studied catalysts. Gold and ceria particle agglomeration or coke formation should be excluded as a possible reason, and the most probable explanation could be associated with the importance of the benzene activation stage. Full article
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Open AccessArticle Effects of Support and Synthetic Procedure for Sol-Immobilized Au Nanoparticles
Catalysts 2016, 6(6), 87; https://doi.org/10.3390/catal6060087
Received: 15 March 2016 / Revised: 17 May 2016 / Accepted: 6 June 2016 / Published: 20 June 2016
Cited by 3 | PDF Full-text (7168 KB) | HTML Full-text | XML Full-text
Abstract
New gold catalysts supported on CeO2, ZrO2 and TiO2 were synthesized by two different techniques: deposition-precipitation and colloidal method. The role of the surfactant (PVA, PVP, THPC) was also investigated. The catalysts were tested in the oxidation of glucose
[...] Read more.
New gold catalysts supported on CeO2, ZrO2 and TiO2 were synthesized by two different techniques: deposition-precipitation and colloidal method. The role of the surfactant (PVA, PVP, THPC) was also investigated. The catalysts were tested in the oxidation of glucose to gluconic acid, in aqueous environment and under mild conditions (60 °C and atmospheric pressure). TEM and SEM analyses have shown that the small size of gold nanoparticles is a necessary condition, but not sufficient for a good conversion. In fact, for an active sample, we have verified that the excess of surfactant must be removed because it would coat the surface of the catalyst. The surfactant, however, should not be completely eliminated, since it has the fundamental role of stabilizing the sample preventing nanoparticles from aggregation. It was evidenced that both the synthetic approach and the kind of support affect the catalysts’ activity. In fact, by focusing on the three different supports, with all the preparation methods, the ceria has proved to be the best support. This is due to its ability to obtain small gold nanoparticles and to its ability to accumulate oxygen. The most appropriate synthesis methodology proved to be the colloidal method with PVA. Recyclability issue was investigated too. Full article
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2014

Jump to: 2018, 2017, 2016, 2013, 2012, 2011

Open AccessEditorial New Trends in Gold Catalysts
Catalysts 2014, 4(3), 299-304; https://doi.org/10.3390/catal4030299
Received: 26 June 2014 / Revised: 9 July 2014 / Accepted: 9 July 2014 / Published: 16 July 2014
Cited by 5 | PDF Full-text (991 KB) | HTML Full-text | XML Full-text
Abstract
Gold is an element that has fascinated mankind for millennia. The catalytic properties of gold have been a source of debate, due to its complete chemical inertness when in a bulk form, while it can oxidize CO at temperatures as low as ~200
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Gold is an element that has fascinated mankind for millennia. The catalytic properties of gold have been a source of debate, due to its complete chemical inertness when in a bulk form, while it can oxidize CO at temperatures as low as ~200 K when in a nanocrystalline state, as discovered by Haruta in the late 1980s [1]. Since then, extensive activity in both applied and fundamental research on gold has been initiated. The importance of the catalysis by gold represents one of the fasted growing fields in science and is proven by the promising applications in several fields, such as green chemistry and environmental catalysis, in the synthesis of single-walled carbon nanotubes, as modifiers of Ni catalysts for methane steam and dry reforming reactions and in biological and electrochemistry applications. The range of reactions catalyzed by gold, as well as the suitability of different supports and the influence of the preparation conditions have been widely explored and optimized in applied research [2]. Gold catalysts appeared to be very different from the other noble metal-based catalysts, due to their marked dependence on the preparation method, which is crucial for the genesis of the catalytic activity. Several methods, including deposition-precipitation, chemical vapor deposition and cation adsorption, have been applied for the preparation of gold catalysts over reducible oxides, like TiO2. Among these methods, deposition-precipitation has been the most frequently employed method for Au loading, and it involves the use of tetrachloroauric (III) acid as a precursor. On the other hand, the number of articles dealing with Au-loaded acidic supports is smaller than that on basic supports, possibly because the deposition of [AuCl4] or [AuOHxCl4x] species on acidic supports is difficult, due to their very low point of zero charge. Despite this challenge, several groups have reported the use of acidic zeolites as supports for gold. Zeolites are promising supports for Au stabilization, because of the presence of ion-exchange sites, such as NH4+, that can be substituted by Au+ ions through the elimination of NH4Cl [3]. Moreover, zeolites, due to their high thermal stability, the presence of a large surface area and micropores, may hinder Au sintering. [...] Full article
Open AccessReview Gold Nanoparticles as the Catalyst of Single-Walled Carbon Nanotube Synthesis
Catalysts 2014, 4(1), 38-48; https://doi.org/10.3390/catal4010038
Received: 29 July 2013 / Revised: 20 February 2014 / Accepted: 24 February 2014 / Published: 5 March 2014
Cited by 8 | PDF Full-text (530 KB) | HTML Full-text | XML Full-text
Abstract
Gold nanoparticles have been proven to act as efficient catalysts for chemical reactions, such as oxidation and hydrogen production. In this review we focus on a different aspect of the catalysis of gold nanoparticles; single-walled carbon nanotube (SWCNT) synthesis. This is not a
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Gold nanoparticles have been proven to act as efficient catalysts for chemical reactions, such as oxidation and hydrogen production. In this review we focus on a different aspect of the catalysis of gold nanoparticles; single-walled carbon nanotube (SWCNT) synthesis. This is not a traditional meaning of catalytic reaction, but SWCNTs cannot be synthesized without nanoparticles. Previously, gold was considered as unsuitable metal species as the catalyst of SWCNT synthesis. However, gold nanoparticles with diameters smaller than 5 nm were found to effectively produce SWCNTs. We discuss the catalysis of gold and related metals for SWCNT synthesis in comparison with conventional catalysts, such as iron, cobalt, and nickel. Full article
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2013

Jump to: 2018, 2017, 2016, 2014, 2012, 2011

Open AccessArticle Influence of Gold on Hydrotalcite-like Compound Catalysts for Toluene and CO Total Oxidation
Catalysts 2013, 3(4), 966-977; https://doi.org/10.3390/catal3040966
Received: 17 November 2013 / Revised: 3 December 2013 / Accepted: 3 December 2013 / Published: 12 December 2013
Cited by 8 | PDF Full-text (333 KB) | HTML Full-text | XML Full-text
Abstract
X6Al2HT500 hydrotalcites, where X represents Mg, Fe, Cu or Zn were synthetized and investigated before and after gold deposition for toluene and CO total oxidation reactions. The samples have been characterized by specific areas, XRD measurements and Temperature Programmed
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X6Al2HT500 hydrotalcites, where X represents Mg, Fe, Cu or Zn were synthetized and investigated before and after gold deposition for toluene and CO total oxidation reactions. The samples have been characterized by specific areas, XRD measurements and Temperature Programmed Reduction. Concerning the toluene total oxidation, the best activity was obtained with Au/Cu6Al2HT500 catalyst with T50 at 260 °C. However, catalytic behavior of Au/X6Al2HT500 sample in both reactions depends mainly on the nature of the support. Full article
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Open AccessReview Gold Nanoparticle-Biological Molecule Interactions and Catalysis
Catalysts 2013, 3(3), 683-708; https://doi.org/10.3390/catal3030683
Received: 18 May 2013 / Revised: 1 August 2013 / Accepted: 12 August 2013 / Published: 3 September 2013
Cited by 10 | PDF Full-text (2603 KB) | HTML Full-text | XML Full-text
Abstract
This review gives a brief summary of the field of gold nanoparticle interactions with biological molecules, particularly those with possible catalytic relevance. Gold nanoparticles are well known as catalysts in organic chemistry but much is unknown regarding their potential as catalysts of reactions
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This review gives a brief summary of the field of gold nanoparticle interactions with biological molecules, particularly those with possible catalytic relevance. Gold nanoparticles are well known as catalysts in organic chemistry but much is unknown regarding their potential as catalysts of reactions involving biological molecules such as protein and nucleic acids. Biological molecules may be the substrate for catalysis or, if they are the ligand coating the gold particle, may be the catalyst itself. In other cases biological molecules may form a template upon which gold nanoparticles can be precisely arrayed. As relatively little is currently known about the catalytic capabilities of gold nanoparticles in this area, this review will consider templating in general (including, but not restricted to, those which result in structures having potential as catalysts) before going on to consider firstly catalysis by the gold nanoparticle itself followed by catalysis by ligands attached to gold nanoparticles, all considered with a focus on biological molecules. Full article
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Open AccessArticle Investigation on the Stability of Supported Gold Nanoparticles
Catalysts 2013, 3(3), 656-670; https://doi.org/10.3390/catal3030656
Received: 19 June 2013 / Revised: 1 August 2013 / Accepted: 12 August 2013 / Published: 21 August 2013
Cited by 7 | PDF Full-text (4520 KB) | HTML Full-text | XML Full-text
Abstract
The procedures leading to the preservation of catalytic performances of Au/ZrO2 samples have been investigated. The three potential causes of deactivation, namely the particle growth by sintering of gold nanoparticles, the metal leaching and the formation of un-reactive species which inhibit the
[...] Read more.
The procedures leading to the preservation of catalytic performances of Au/ZrO2 samples have been investigated. The three potential causes of deactivation, namely the particle growth by sintering of gold nanoparticles, the metal leaching and the formation of un-reactive species which inhibit the reaction, have been evaluated. In particular, this paper deals with the stability of gold nanoparticles: (1) under storage conditions; (2) with time on stream for a gas phase reaction (LT-WGSR); (3) with time on stream for a liquid phase reaction (furfural oxidative esterification). Full article
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Open AccessArticle Fabrication and Catalytic Activity of Thermally Stable Gold Nanoparticles on Ultrastable Y (USY) Zeolites
Catalysts 2013, 3(3), 599-613; https://doi.org/10.3390/catal3030599
Received: 22 April 2013 / Revised: 17 June 2013 / Accepted: 1 July 2013 / Published: 9 July 2013
Cited by 5 | PDF Full-text (1231 KB) | HTML Full-text | XML Full-text
Abstract
Au was deposited on ultrastable Y (USY) zeolites using an ion-exchange method. Up to 5.5 wt% Au was introduced into the NH4-form of USY zeolites. In contrast, deposition of Au hardly took place on the H- and Na-forms of Y-type zeolites,
[...] Read more.
Au was deposited on ultrastable Y (USY) zeolites using an ion-exchange method. Up to 5.5 wt% Au was introduced into the NH4-form of USY zeolites. In contrast, deposition of Au hardly took place on the H- and Na-forms of Y-type zeolites, NH4-forms of mordenite, and ZSM-5. Treatment of the Au-loaded USY zeolite in a H2 atmosphere, afforded Au0 nanoparticles. These particles were thermally stable even at 973 K, where their mean particle diameter was 3.7 nm. In contrast, highly aggregated Au particles were observed after thermal treatment at temperatures lower than 523 K, followed by storage in air for a month. The resulting particle sizes were in good correlation with the IR band intensity of the adsorbed CO and the catalytic activity of Au in the aerobic oxidation of benzyl alcohol. The Au nanoparticles showed highest activity when the Au/USY zeolite was thermally treated at 673–973 K. A negligible deactivation was observed after repeating the reaction at least 12 times. In the case of Au/TiO2 catalyst prepared by the deposition-precipitation method, the highest activity was observed at 573 K, which was lower than the temperature used for the Au/USY zeolites. This study demonstrated the potential use of the NH4-form of USY zeolites for supporting Au. Full article
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Open AccessArticle Ni-Based Catalysts for Low Temperature Methane Steam Reforming: Recent Results on Ni-Au and Comparison with Other Bi-Metallic Systems
Catalysts 2013, 3(2), 563-583; https://doi.org/10.3390/catal3020563
Received: 9 April 2013 / Revised: 22 May 2013 / Accepted: 30 May 2013 / Published: 5 June 2013
Cited by 60 | PDF Full-text (1439 KB) | HTML Full-text | XML Full-text
Abstract
Steam reforming of light hydrocarbons provides a promising method for hydrogen production. Ni-based catalysts are so far the best and the most commonly used catalysts for steam reforming because of their acceptably high activity and significantly lower cost in comparison with alternative precious
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Steam reforming of light hydrocarbons provides a promising method for hydrogen production. Ni-based catalysts are so far the best and the most commonly used catalysts for steam reforming because of their acceptably high activity and significantly lower cost in comparison with alternative precious metal-based catalysts. However, nickel catalysts are susceptible to deactivation from the deposition of carbon, even when operating at steam-to-carbon ratios predicted to be thermodynamically outside of the carbon-forming regime. Reactivity and deactivation by carbon formation can be tuned by modifying Ni surfaces with a second metal, such as Au through alloy formation. In the present review, we summarize the very recent progress in the design, synthesis, and characterization of supported bimetallic Ni-based catalysts for steam reforming. The progress in the modification of Ni with noble metals (such as Au and Ag) is discussed in terms of preparation, characterization and pretreatment methods. Moreover, the comparison with the effects of other metals (such as Sn, Cu, Co, Mo, Fe, Gd and B) is addressed. The differences of catalytic activity, thermal stability and carbon species between bimetallic and monometallic Ni-based catalysts are also briefly shown. Full article
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Open AccessArticle Electron Transfer at Gold Nanostar Assemblies: A Study of Shape Stability and Surface Density Influence
Catalysts 2013, 3(1), 288-309; https://doi.org/10.3390/catal3010288
Received: 17 January 2013 / Revised: 25 February 2013 / Accepted: 26 February 2013 / Published: 12 March 2013
Cited by 15 | PDF Full-text (5075 KB) | HTML Full-text | XML Full-text
Abstract
Gold nanostars of ~70 nm tip to tip distances were synthesized by a seed mediated method and covalently self-assembled on 1,5-pentanedithiol modified electrodes. Electron transfer kinetics at the AuNS/dithiol modified electrodes were studied as a function of AuNS surface density which was varied
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Gold nanostars of ~70 nm tip to tip distances were synthesized by a seed mediated method and covalently self-assembled on 1,5-pentanedithiol modified electrodes. Electron transfer kinetics at the AuNS/dithiol modified electrodes were studied as a function of AuNS surface density which was varied by increasing their self-assembly time from 8 h, 16 h, 24 h to 32 h. Excellent electrocatalytic properties of AuNSs were observed toward electrochemistry of [Fe(CN)6]4−/3− redox couple. The apparent heterogeneous electron transfer constant, ket, has progressively increased with the surface density of AuNSs bonded to the electrodes from 0.65 × 10−5 cm s−1 (8 h), 1.47 × 10−5 cm s−1 (16 h), 3.95 × 10−5 cm s−1 (24 h) to an excellent 85.0 × 10−5 cm s−1 (32 h). Electrochemical charging of nanostars was confirmed, for the first time, by 79 times increase of double layer capacitance, Cdl, from 0.34 µF (8 h) to 27 µF (32 h). The electrochemical charging of AuNSs had also a strong influence on the electron tunneling process through the 1,5PDT molecules being more efficient at dense layers of AuNSs. The tunneling parameter, β, has decreased from 1.13 Å−1 (16 h) to 0.50 Å−1 (32 h). The AuNSs were chemically stable toward [Fe(CN)6]4−/3− showing no change in shape after electrochemical measurements. Full article
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Open AccessArticle Defect-Driven Restructuring of TiO2 Surface and Modified Reactivity Toward Deposited Gold Atoms
Catalysts 2013, 3(1), 276-287; https://doi.org/10.3390/catal3010276
Received: 11 January 2013 / Revised: 17 February 2013 / Accepted: 19 February 2013 / Published: 8 March 2013
Cited by 2 | PDF Full-text (1868 KB) | HTML Full-text | XML Full-text
Abstract
A partially reduced TiO2 surface exhibits increasingly complex nature when forming various defects, whose stoichiometry, structure and properties are markedly different from those of bulk TiO2. Using scanning tunneling microscopy and density functional theory, we investigate different types of surface defects formed by
[...] Read more.
A partially reduced TiO2 surface exhibits increasingly complex nature when forming various defects, whose stoichiometry, structure and properties are markedly different from those of bulk TiO2. Using scanning tunneling microscopy and density functional theory, we investigate different types of surface defects formed by Ti interstitials on TiO2 (110) and their reactivity toward deposited gold atoms. Sub-stoichiometric strands greatly enhance bonding of Au by transferring the excess charges from the reduced Ti3+ onto the strands. Thus the sub-stoichiometric strands behave as strong electron donor sites toward reactants. On the contrary, fully stoichiometric nanoclusters provide increased Au bonding through its 1-coordinated oxygen, which acts as a strong electron acceptor site. Specific interactions between Au and defects as well as the implication of electron donor/acceptor complexes for catalytic reactions are discussed. Full article
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2012

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Open AccessEditorial New Frontiers in Gold Catalyzed Reactions
Catalysts 2012, 2(2), 299-302; https://doi.org/10.3390/catal2020299
Received: 24 April 2012 / Revised: 18 May 2012 / Accepted: 21 May 2012 / Published: 29 May 2012
Cited by 4 | PDF Full-text (76 KB) | HTML Full-text | XML Full-text
Abstract
For many years, gold has been regarded as a poor catalyst due to its chemical inertness towards reactive molecules such as oxygen and hydrogen. The interest in using gold in catalysis has increased during the last 20 years, since Haruta reported the surprisingly
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For many years, gold has been regarded as a poor catalyst due to its chemical inertness towards reactive molecules such as oxygen and hydrogen. The interest in using gold in catalysis has increased during the last 20 years, since Haruta reported the surprisingly high activity in CO oxidation at low temperature for small (3–5 nm) gold particles supported on various oxides. [...] Full article
Open AccessArticle Influence of Gold on Ce-Zr-Co Fluorite-Type Mixed Oxide Catalysts for Ethanol Steam Reforming
Catalysts 2012, 2(1), 121-138; https://doi.org/10.3390/catal2010121
Received: 9 January 2012 / Revised: 18 January 2012 / Accepted: 27 January 2012 / Published: 3 February 2012
Cited by 8 | PDF Full-text (494 KB) | HTML Full-text | XML Full-text
Abstract
The effect of gold presence on carbon monoxide oxidation and ethanol steam reforming catalytic behavior of two Ce-Zr-Co mixed oxides catalysts with a constant Co charge and different Ce/Zr ratios was investigated. The Ce-Zr-Co mixed oxides were obtained by the pseudo sol-gel like
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The effect of gold presence on carbon monoxide oxidation and ethanol steam reforming catalytic behavior of two Ce-Zr-Co mixed oxides catalysts with a constant Co charge and different Ce/Zr ratios was investigated. The Ce-Zr-Co mixed oxides were obtained by the pseudo sol-gel like method, based on metallic propionates polymerization and thermal decomposition, whereas the gold-supported Ce-Zr-Co mixed oxides catalysts were prepared using the direct anionic exchange. The catalysts were characterized using XRD, TPR, and EDXS-TEM. The presence of Au in doped Ce-Zr-Co oxide catalyst decreases the temperature necessary to reduce the cobalt and the cerium loaded in the catalyst and favors a different reaction pathway, improving the acetaldehyde route by ethanol dehydrogenation, instead of the ethylene route by ethanol dehydration or methane re-adsorption, thus increasing the catalytic activity and selectivity into hydrogen. Full article
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Open AccessReview Monometallic Supported Gold Catalysts in Organic Transformations: Ring Making and Ring Breaking
Catalysts 2012, 2(1), 101-120; https://doi.org/10.3390/catal2010101
Received: 10 October 2011 / Revised: 19 December 2011 / Accepted: 9 January 2012 / Published: 1 February 2012
Cited by 3 | PDF Full-text (970 KB) | HTML Full-text | XML Full-text
Abstract
Supported gold catalysts are highly active in oxidation reactions. Beside the most frequently studied CO oxidation, they are readily applied in the epoxidation of more or less complex olefinic compounds using air or oxygen directly or other oxidants like peroxides of various kinds.
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Supported gold catalysts are highly active in oxidation reactions. Beside the most frequently studied CO oxidation, they are readily applied in the epoxidation of more or less complex olefinic compounds using air or oxygen directly or other oxidants like peroxides of various kinds. Less frequently though, the reverse reaction, ring opening with single or double C–O scission is also investigated. These and other ring making and breaking reactions are reviewed, and the catalytic roles of gold species are described. Full article
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2011

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Open AccessArticle The Influence of Base Metal (M) Oxidation State in Au-M-O/TiO2 Systems on Their Catalytic Activity in Carbon Monoxide Oxidation
Catalysts 2012, 2(1), 38-55; https://doi.org/10.3390/catal2010038
Received: 6 October 2011 / Revised: 5 November 2011 / Accepted: 7 December 2011 / Published: 22 December 2011
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Abstract
Base metal promoted gold/titania catalysts were synthesized, characterized and tested in CO oxidation reaction. Catalysts containing dopant metals in higher oxidation states exhibited higher activity than catalysts containing dopants in reduced states. The activity of fresh catalysts promoted by Cu, Fe and Ni
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Base metal promoted gold/titania catalysts were synthesized, characterized and tested in CO oxidation reaction. Catalysts containing dopant metals in higher oxidation states exhibited higher activity than catalysts containing dopants in reduced states. The activity of fresh catalysts promoted by Cu, Fe and Ni was similar to the unpromoted one, but treatment in reducing and oxidizing atmospheres revealed the supremacy of the copper promoted catalyst. The sequential deposition method proved to be better than the co-deposition—precipitation method. An attempt to explain these differences using XPS, FTIR and H2 TPR was performed. Full article
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Open AccessReview The Art of Manufacturing Gold Catalysts
Catalysts 2012, 2(1), 24-37; https://doi.org/10.3390/catal2010024
Received: 17 October 2011 / Revised: 21 November 2011 / Accepted: 7 December 2011 / Published: 21 December 2011
Cited by 30 | PDF Full-text (1600 KB) | HTML Full-text | XML Full-text
Abstract
Gold has been considered as an active catalyst only when suitable techniques of preparation provided high metal dispersion. A comprehensive survey of the different methods now available for preparing active gold catalysts is reported with particular attention to the role of the supporting
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Gold has been considered as an active catalyst only when suitable techniques of preparation provided high metal dispersion. A comprehensive survey of the different methods now available for preparing active gold catalysts is reported with particular attention to the role of the supporting material in determining catalyst characteristics. Full article
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Open AccessArticle Gold/Iron Carbonyl Clusters for Tailored Au/FeOx Supported Catalysts
Catalysts 2012, 2(1), 1-23; https://doi.org/10.3390/catal2010001
Received: 6 October 2011 / Revised: 1 December 2011 / Accepted: 6 December 2011 / Published: 21 December 2011
Cited by 13 | PDF Full-text (1617 KB) | HTML Full-text | XML Full-text
Abstract
A novel preparation method was developed for the preparation of gold/iron oxide supported catalysts using the bimetallic carbonyl cluster salts [NEt4]4[Au4Fe4(CO)16] and [NEt4][AuFe4(CO)16] as precursors of highly
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A novel preparation method was developed for the preparation of gold/iron oxide supported catalysts using the bimetallic carbonyl cluster salts [NEt4]4[Au4Fe4(CO)16] and [NEt4][AuFe4(CO)16] as precursors of highly dispersed nanoparticles over different supports. A series of catalysts with different metal loadings were prepared and tested in the complete oxidation of dichlorobenzene, toluene, methanol and in the preferential oxidation of CO in the presence of H2 (PROX) as model reactions. The characterization by BET, XRD, TEM, H2-TPR, ICP-AES and XPS point out the way the nature of the precursors and the thermal treatment conditions affected the dispersion of the active phase and their catalytic activity in the studied reactions. Full article
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Open AccessArticle Pre-Reduction of Au/Iron Oxide Catalyst for Low-Temperature Water-Gas Shift Reaction Below 150 °C
Catalysts 2011, 1(1), 175-190; https://doi.org/10.3390/catal1010175
Received: 6 October 2011 / Revised: 14 November 2011 / Accepted: 29 November 2011 / Published: 9 December 2011
Cited by 9 | PDF Full-text (907 KB) | HTML Full-text | XML Full-text
Abstract
Low-temperature water-gas shift reaction (WGS) using gold catalyst is expected to be an attractive technique to realize an efficient on-site hydrogen production process. In this paper, Au/Fe3O4 catalysts for promoting the WGS below 150 °C were developed by a preliminary
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Low-temperature water-gas shift reaction (WGS) using gold catalyst is expected to be an attractive technique to realize an efficient on-site hydrogen production process. In this paper, Au/Fe3O4 catalysts for promoting the WGS below 150 °C were developed by a preliminary reduction of Au/iron oxide (Fe3+) catalyst utilizing high reactivity of Au nano-particles. The reduction was conducted under a CO, H2, or CO/H2O stream at either 140 or 200 °C, and the effect of reduction conditions on the characteristics of the Au/Fe3O4 catalyst and on the catalytic activity in WGS at 80 °C was investigated. The reaction progress during the pre-reduction treatment was qualitatively analyzed, and it was found that the iron oxide in Au/Fe2O3 calcined at 200 °C was easily reduced to Fe3O4 phase in all reduction conditions. The reduction conditions affected the characteristics of both Au and iron oxide, but all of the reduced catalysts had small Fe3O4 particles of less than 20 nm with Au particles on the surface. The surface area and content of cationic Au were high in the order of CO, H2, CO/H2O, and 140, 200 °C. In the WGS test at 80 °C using the developed catalysts, the activities of the catalysts pre-reduced by CO at 140 or 200 °C and by H2 at 140 °C were very high with 100% CO conversion even at such a low temperature. These results indicated that factors such as higher surface area, crystallized Fe3O4, and cationic Au content contributed to the catalytic activity. Full article
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Open AccessArticle Nano-Scale Au Supported on Carbon Materials for the Low Temperature Water Gas Shift (WGS) Reaction
Catalysts 2011, 1(1), 155-174; https://doi.org/10.3390/catal1010155
Received: 11 October 2011 / Revised: 4 November 2011 / Accepted: 29 November 2011 / Published: 9 December 2011
Cited by 5 | PDF Full-text (6721 KB) | HTML Full-text | XML Full-text
Abstract
Au-based catalysts supported on carbon materials with different structures such as graphite (G) and fishbone type carbon nanofibers (CNF-F) were prepared using two different methods (impregnation and gold-sol) to be tested in the water gas shift (WGS) reaction. Atomic absorption spectrometry, transmission electron
[...] Read more.
Au-based catalysts supported on carbon materials with different structures such as graphite (G) and fishbone type carbon nanofibers (CNF-F) were prepared using two different methods (impregnation and gold-sol) to be tested in the water gas shift (WGS) reaction. Atomic absorption spectrometry, transmission electron microscopy (TEM), temperature-programmed oxidation (TPO), X-ray diffraction (XRD), Raman spectroscopy, elemental analyses (CNH), N2 adsorption-desorption analysis, temperature-programmed reduction (TPR) and temperature-programmed decomposition were employed to characterize both the supports and catalysts. Both the crystalline nature of the carbon supports and the method of gold incorporation had a strong influence on the way in which Au particles were deposited on the carbon surface. The higher crystallinity and the smaller and well dispersed Au particle size were, the higher activity of the catalysts in the WGS reaction was noted. Finally, catalytic activity showed an important dependence on the reaction temperature and steam-to-CO molar ratio. Full article
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Open AccessReview Synthesis of Gold Catalysts Supported on Mesoporous Silica Materials: Recent Developments
Catalysts 2011, 1(1), 97-154; https://doi.org/10.3390/catal1010097
Received: 13 October 2011 / Revised: 24 November 2011 / Accepted: 25 November 2011 / Published: 2 December 2011
Cited by 59 | PDF Full-text (1316 KB) | HTML Full-text | XML Full-text
Abstract
Mesoporous silica materials (MSM) with ordered and controllable porous structure, high surface area, pore volume and thermal stability are very suitable catalyst supports, because they provide high dispersion of metal nanoparticles and facilitate the access of the substrates to the active sites. Since
[...] Read more.
Mesoporous silica materials (MSM) with ordered and controllable porous structure, high surface area, pore volume and thermal stability are very suitable catalyst supports, because they provide high dispersion of metal nanoparticles and facilitate the access of the substrates to the active sites. Since the conventional wet-impregnation and deposition-precipitation methods are not appropriate for the incorporation of gold nanoparticles (AuNPs) into MSM, considerable efforts have been made to develop suitable methods to synthesize Au/MSM catalysts, because the incorporation of AuNPs into the channel system can prevent their agglomeration and leaching. In this review, we summarize the main methods to synthesize active gold catalysts supported on MSM. Examples and details of the preparative methods, as well as selected applications are provided. We expect this article to be interesting to researchers due to the wide variety of chemical reactions that can be catalyzed by gold supported catalysts. Full article
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Open AccessArticle Synthesis and Catalytic Features of Hybrid Metal Nanoparticles Supported on Cellulose Nanofibers
Catalysts 2011, 1(1), 83-96; https://doi.org/10.3390/catal1010083
Received: 6 October 2011 / Revised: 15 November 2011 / Accepted: 18 November 2011 / Published: 25 November 2011
Cited by 43 | PDF Full-text (1124 KB) | HTML Full-text | XML Full-text
Abstract
The structural and functional design of metal nanoparticles has recently allowed remarkable progress in the development of high-performance catalysts. Gold nanoparticles (AuNPs) are among the most innovative catalysts, despite bulk Au metal being regarded as stable and inactive. The hybridization of metal NPs
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The structural and functional design of metal nanoparticles has recently allowed remarkable progress in the development of high-performance catalysts. Gold nanoparticles (AuNPs) are among the most innovative catalysts, despite bulk Au metal being regarded as stable and inactive. The hybridization of metal NPs has attracted major interest in the field of advanced nanocatalysts, due to electro-mediated ligand effects. In practical terms, metal NPs need to be supported on a suitable matrix to avoid any undesirable aggregation; many researchers have reported the potential of polymer-supported AuNPs. However, the use of conventional polymer matrices make it difficult to take full advantage of the inherent properties of the metal NPs, since most of active NPs are imbedded inside the polymer support. This results in poor accessibility for the reactants. Herein, we report the topochemical synthesis of Au and palladium (Pd) bimetallic NPs over the surfaces of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers (TOCNs), and their exceptional catalytic performance. Highly-dispersed AuPdNPs were successfully synthesized in situ on the crystal surfaces of TOCNs with a very high density of carboxylate groups. The AuPdNPs@TOCN nanocomposites exhibit excellent catalytic efficiencies in the aqueous reduction of 4-nitrophenol to 4-aminophenol, depending on the molar ratios of Au and Pd. Full article
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Open AccessArticle In Situ Synthesis of Bimetallic Hybrid Nanocatalysts on a Paper-Structured Matrix for Catalytic Applications
Catalysts 2011, 1(1), 69-82; https://doi.org/10.3390/catal1010069
Received: 25 September 2011 / Revised: 14 November 2011 / Accepted: 18 November 2011 / Published: 25 November 2011
Cited by 10 | PDF Full-text (1236 KB) | HTML Full-text | XML Full-text
Abstract
Bimetallic nanoparticles have attracted significant attention as their electrochemical and catalytic properties being superior to those of the individual component nanoparticles. In this study, gold-silver hybrid nanoparticles (AuAgNPs) with an Aucore-Agshell nanostructure were successfully synthesized on zinc oxide (ZnO) whiskers.
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Bimetallic nanoparticles have attracted significant attention as their electrochemical and catalytic properties being superior to those of the individual component nanoparticles. In this study, gold-silver hybrid nanoparticles (AuAgNPs) with an Aucore-Agshell nanostructure were successfully synthesized on zinc oxide (ZnO) whiskers. The as-prepared nanocatalyst, denoted AuAgNPs@ZnO whisker, exhibits an excellent catalytic efficiency in the aqueous reduction of 4-nitrophenol to 4-aminophenol; the turnover frequency was up to 40 times higher than that of each component nanoparticle. Their unique features were attributed to the electronic ligand effect at the bimetallic interface. In addition, the AuAgNPs were synthesized on a ZnO whisker-containing paper with a fiber-network microstructure, which was prepared via a papermaking technique. The paper-structured AuAgNPs composite possessed both a paper-like practical utility and a good catalytic performance. Furthermore, the on-paper synthesis process for these bimetallic nanocatalysts is facile. These easy-to-handle nanocatalyst hybrid composites are expected to find a wide range of applications in various chemical and catalytic processes. Full article
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Open AccessArticle Gold Functionalized Supported Ionic Liquids Catalyst for CO Oxidation
Catalysts 2011, 1(1), 52-68; https://doi.org/10.3390/catal1010052
Received: 21 September 2011 / Revised: 17 October 2011 / Accepted: 17 November 2011 / Published: 25 November 2011
Cited by 3 | PDF Full-text (755 KB) | HTML Full-text | XML Full-text
Abstract
The present study tries to give an insight to the combination of the homogeneous and heterogeneous catalytic properties in a new class of materials. Well dispersed gold nanoparticles on an ionic liquid layer supported on a mineral carrier have been prepared. This work
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The present study tries to give an insight to the combination of the homogeneous and heterogeneous catalytic properties in a new class of materials. Well dispersed gold nanoparticles on an ionic liquid layer supported on a mineral carrier have been prepared. This work is concentrated on the characterizations and understanding of the interactions between all the components of the catalytic system. The application of the materials in the reaction of oxidation of carbon monoxide shows rather unexpected results—a good catalytic activity completely independent of the temperature. Full article
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Open AccessReview Catalytic Reactions on Model Gold Surfaces: Effect of Surface Steps and of Surface Doping
Catalysts 2011, 1(1), 40-51; https://doi.org/10.3390/catal1010040
Received: 6 October 2011 / Revised: 11 November 2011 / Accepted: 15 November 2011 / Published: 21 November 2011
Cited by 4 | PDF Full-text (443 KB) | HTML Full-text | XML Full-text
Abstract
The adsorption energies and the activation energy barriers for a series of reactions catalyzed by gold surfaces and obtained theoretically through density functional theory (DFT) based calculations were considered to clarify the role of the low coordinated gold atoms and the role of
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The adsorption energies and the activation energy barriers for a series of reactions catalyzed by gold surfaces and obtained theoretically through density functional theory (DFT) based calculations were considered to clarify the role of the low coordinated gold atoms and the role of doping in the catalytic activity of gold. The effect of the surface steps was introduced by comparison of the activation energy barriers and of the adsorption energies on flat gold surfaces such as the Au(111) surface with those on stepped surfaces such as the Au(321) or the Au(110) surfaces. It is concluded that the presence of low coordinated atoms on the latter surfaces increases the adsorption energies of the reactants and decreases the activation energy barriers. Furthermore, the increasing of the adsorption energy of the reaction products can lead to lower overall reaction rates in the presence of low gold coordinated atoms due to desorption limitations. On the other hand, the effect of doping gold surfaces with other transition metal atoms was analyzed using the dissociation reaction of molecular oxygen as a test case. The calculations showed that increasing the silver content in some gold surfaces was related to a considerable increment of the reactivity of bimetallic systems toward the oxygen dissociation. Importantly, that increment in the reactivity was enhanced by the presence of low coordinated atoms in the catalytic surface models considered. Full article
Open AccessArticle Role of the Support Effects on the Catalytic Activity of Gold Clusters: A Density Functional Theory Study
Catalysts 2011, 1(1), 18-39; https://doi.org/10.3390/catal1010018
Received: 6 October 2011 / Revised: 31 October 2011 / Accepted: 16 November 2011 / Published: 17 November 2011
Cited by 27 | PDF Full-text (4231 KB) | HTML Full-text | XML Full-text
Abstract
It is demonstrated that the support effects play a crucial role in the gold nanocatalysis. Two types of support are considered—the “inert” support of hexagonal boron nitride (h-BN) with the N and B vacancy defects and the “active” support of rutile TiO2
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It is demonstrated that the support effects play a crucial role in the gold nanocatalysis. Two types of support are considered—the “inert” support of hexagonal boron nitride (h-BN) with the N and B vacancy defects and the “active” support of rutile TiO2(110). It is demonstrated that Au and Au2 can be trapped effectively by the vacancy defects in h-BN. In that case, the strong adsorption on the surface defects is accompanied by the charge transfer to/from the adsorbate. The excess of the positive or negative charge on the supported gold clusters can considerably promote their catalytic activity. Therefore gold clusters supported on the defected h-BN surface can not be considered as pseudo-free clusters. We also demonstrate that the rutile TiO2(110) support energetically promotes H2 dissociation on gold clusters. We show that the formation of the OH group near the supported gold cluster is an important condition for H2 dissociation. We demonstrate that the active sites towards H2 dissociation on the supported Aun are located at corners and edges of the gold cluster in the vicinity of the low coordinated oxygen atoms on TiO2(110). Thus catalytic activity of a gold nanoparticle supported on the rutile TiO2(110) surface is proportional to the length of the perimeter interface between the nanoparticle and the support. Full article
Open AccessReview Atomically Monodisperse Gold Nanoclusters Catalysts with Precise Core-Shell Structure
Catalysts 2011, 1(1), 3-17; https://doi.org/10.3390/catal1010003
Received: 26 July 2011 / Revised: 26 August 2011 / Accepted: 29 August 2011 / Published: 7 September 2011
Cited by 22 | PDF Full-text (1206 KB) | HTML Full-text | XML Full-text
Abstract
The emphasis of this review is atomically monodisperse Aun nanoclusters catalysts (n = number of metal atom in cluster) that are ideally composed of an exact number of metal atoms. Aun which range in size from a dozen to a
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The emphasis of this review is atomically monodisperse Aun nanoclusters catalysts (n = number of metal atom in cluster) that are ideally composed of an exact number of metal atoms. Aun which range in size from a dozen to a few hundred atoms are particularly promising for nanocatalysis due to their unique core-shell structure and non-metallic electronic properties. Aun nanoclusters catalysts have been demonstrated to exhibit excellent catalytic activity in hydrogenation and oxidation processes. Such unique properties of Aun significantly promote molecule activation by enhancing adsorption energy of reactant molecules on catalyst surface. The structural determination of Aun nanoclusters allows for a precise correlation of particle structure with catalytic properties and also permits the identification of catalytically active sites on the gold particle at an atomic level. By learning these fundamental principles, one would ultimately be able to design new types of highly active and highly selective gold nanocluster catalysts for a variety of catalytic processes. Full article
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