Special Issue "Noble Metal Nanoparticles in Catalysis"

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (30 November 2017).

Special Issue Editors

Prof. Dr. Ioannis N. Lykakis
Website
Guest Editor
Department of Chemistry, Aristotle University of Thessaloniki, University Campus, Thessaloniki 54124, Greece
Interests: Photocatalysis, Organic Chemistry, Green Chemistry, Synthetic Organic Methodologies, Catalysis of Organic Transformations with Metal Nanoparticles, Multi-Component Reactions, Heterocyclic Molecule Synthesis
Prof. Dr. Gerasimos S. Armatas
Website
Guest Editor
Department of Materials Science and Technology, University of Crete, Heraklion, 71003, Greece
Interests: mesoporous materials; semiconductor nanoparticles, self-assembly, photocatalysis, water splitting; catalysis

Special Issue Information

Dear Colleagues,

Since the beginning of the millennium, the field of noble-metal nanoparticle catalysis has emerged as one of the top subjects in scientific community. The spectacular properties of these nanoscale elements, such as tunable surface plasmon and photo thermal effects, excellent resistant to corrosion and air oxidation and lesser cytotoxicity, as well as their easy experimental realization make them excellent candidates for biological, opto-electronic and environmental related applications. Among them, Au, Pt and Ag nanoparticles can be taken as examples to demonstrate the relevance and diversity of catalytic functions that can be sustained by noble metals in general. In this Special Issue on “Noble Metal Nanoparticles in Catalysis” a series of original contributions made by leading experts in the field is expected to highlight recent advances and future perspectives of this emerging topic. These research articles are intended to cover various aspects of noble-metal nanoparticle science and technology, including synthesis, structural characterization, theoretical study and catalytic applications in a diverse range of reactions ranging from total synthesis of natural and pharmaceutical products, to water treatment and medicinal area, and to new organic transformations.

Prof. Dr. Ioannis N. Lykakis
Prof. Dr. Gerasimos S.Armatas
Guest Editors

Manuscript Submission Information

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Keywords

  • Gold nanoparticles
  • Silver nanoparticles
  • Platinum nanoparticles
  • Catalysis
  • Green chemistry
  • Nanostructured materials
  • Hydrogen generation
  • Redox organic trasnformations
  • Biological and enviromental applications
  • Medicinal applications

Published Papers (7 papers)

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Research

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Open AccessArticle
UV-Vis-Induced Degradation of Phenol over Magnetic Photocatalysts Modified with Pt, Pd, Cu and Au Nanoparticles
Nanomaterials 2018, 8(1), 28; https://doi.org/10.3390/nano8010028 - 07 Jan 2018
Cited by 23
Abstract
The combination of TiO2 photocatalyst and magnetic oxide nanoparticles enhances the separation and recoverable properties of nanosized TiO2 photocatalyst. Metal-modified (Me = Pd, Au, Pt, Cu) TiO2/SiO2@Fe3O4 nanocomposites were prepared by an ultrasonic-assisted sol-gel [...] Read more.
The combination of TiO2 photocatalyst and magnetic oxide nanoparticles enhances the separation and recoverable properties of nanosized TiO2 photocatalyst. Metal-modified (Me = Pd, Au, Pt, Cu) TiO2/SiO2@Fe3O4 nanocomposites were prepared by an ultrasonic-assisted sol-gel method. All prepared samples were characterized by X-ray powder diffraction (XRD) analysis, Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), Mott-Schottky analysis and photoluminescence spectroscopy (PL). Phenol oxidation pathways of magnetic photocatalysts modified with Pt, Pd, Cu and Au nanoparticles proceeded by generation of reactive oxygen species, which oxidized phenol to benzoquinone, hydroquinone and catechol. Benzoquinone and maleic acid were products, which were determined in the hydroquinone oxidation pathway. The highest mineralization rate was observed for Pd-TiO2/SiO2@Fe3O4 and Cu-TiO2/SiO2@Fe3O4 photocatalysts, which produced the highest concentration of catechol during photocatalytic reaction. For Pt-TiO2/SiO2@Fe3O4 nanocomposite, a lack of catechol after 60 min of irradiation resulted in low mineralization rate (CO2 formation). It is proposed that the enhanced photocatalytic activity of palladium and copper-modified photocatalysts is related to an increase in the amount of adsorption sites and efficient charge carrier separation, whereas the keto-enol tautomeric equilibrium retards the rate of phenol photomineralization on Au-TiO2/SiO2@Fe3O4. The magnetization hysteresis loop indicated that the obtained hybrid photocatalyst showed magnetic properties and therefore could be easily separated after treatment process. Full article
(This article belongs to the Special Issue Noble Metal Nanoparticles in Catalysis)
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Open AccessArticle
Synthesis of Formate Esters and Formamides Using an Au/TiO2-Catalyzed Aerobic Oxidative Coupling of Paraformaldehyde
Nanomaterials 2017, 7(12), 440; https://doi.org/10.3390/nano7120440 - 12 Dec 2017
Cited by 4
Abstract
A simple method for the synthesis of formate esters and formamides is presented based on the Au/TiO2-catalyzed aerobic oxidative coupling between alcohols or amines and formaldehyde. The suitable form of formaldehyde is paraformaldehyde, as cyclic trimeric 1,3,5-trioxane is inactive. The reaction [...] Read more.
A simple method for the synthesis of formate esters and formamides is presented based on the Au/TiO2-catalyzed aerobic oxidative coupling between alcohols or amines and formaldehyde. The suitable form of formaldehyde is paraformaldehyde, as cyclic trimeric 1,3,5-trioxane is inactive. The reaction proceeds via the formation of an intermediate hemiacetal or hemiaminal, respectively, followed by the Au nanoparticle-catalyzed aerobic oxidation of the intermediate. Typically, the oxidative coupling between formaldehyde (2 equiv) and amines occurs quantitatively at room temperature within 4 h, and there is no need to add a base as in analogous coupling reactions. The oxidative coupling between formaldehyde (typically 3 equiv) and alcohols is unprecedented and occurs more slowly, yet in good to excellent yields and selectivity. Minor side-products (2–12%) from the acetalization of formaldehyde by the alcohol are also formed. The catalyst is recyclable and can be reused after a simple filtration in five consecutive runs with a small loss of activity. Full article
(This article belongs to the Special Issue Noble Metal Nanoparticles in Catalysis)
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Open AccessArticle
Synthesis of Au-Pd Bimetallic Nanoflowers for Catalytic Reduction of 4-Nitrophenol
Nanomaterials 2017, 7(9), 239; https://doi.org/10.3390/nano7090239 - 26 Aug 2017
Cited by 23
Abstract
Due to the great potential to improve catalytic performance, gold (Au) and palladium (Pd) bimetallic catalysts have prompted structure-controlled synthesis of Au-Pd nanoalloys bounded by high-index facets. In this work, we prepared Au-Pd bimetallic nanoflowers (NFs) with a uniform size, well-defined dendritic morphology, [...] Read more.
Due to the great potential to improve catalytic performance, gold (Au) and palladium (Pd) bimetallic catalysts have prompted structure-controlled synthesis of Au-Pd nanoalloys bounded by high-index facets. In this work, we prepared Au-Pd bimetallic nanoflowers (NFs) with a uniform size, well-defined dendritic morphology, and homogeneous alloy structure in an aqueous solution by seed-mediated synthesis. The prepared bimetallic NFs were fully characterized using a combination of transmission electron microscopy, Ultraviolet-Visible (UV-vis) spectroscopy, inductively coupled plasma optical emission spectroscopy, and cyclic voltammetry measurements. The catalytic activities of the prepared Au-Pd nanoparticles for 4-nitrophenol reduction were also investigated, and the activities are in the order of [email protected] NFs > Au-Pd NFs (Au1Pd1 core) > Au-Pd NFs (Au core), which could be related to the content and exposed different reactive surfaces of Pd in alloys. This result clearly demonstrates that the superior activities of Au-Pd alloy nanodendrites could be attributed to the synergy between Au and Pd in catalysts. Full article
(This article belongs to the Special Issue Noble Metal Nanoparticles in Catalysis)
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Open AccessArticle
Radiolytic Synthesis of Pt-Particle/ABS Catalysts for H2O2 Decomposition in Contact Lens Cleaning
Nanomaterials 2017, 7(9), 235; https://doi.org/10.3390/nano7090235 - 23 Aug 2017
Cited by 2
Abstract
A container used in contact lens cleaning requires a Pt plating weight of 1.5 mg for H2O2 decomposition although Pt is an expensive material. Techniques that decrease the amount of Pt are therefore needed. In this study, Pt nanoparticles instead [...] Read more.
A container used in contact lens cleaning requires a Pt plating weight of 1.5 mg for H2O2 decomposition although Pt is an expensive material. Techniques that decrease the amount of Pt are therefore needed. In this study, Pt nanoparticles instead of Pt plating film were supported on a substrate of acrylonitrile–butadiene–styrene copolymer (ABS). This was achieved by the reduction of Pt ions in an aqueous solution containing the ABS substrate using high-energy electron-beam irradiation. Pt nanoparticles supported on the ABS substrate (Pt-particle/ABS) had a size of 4–10 nm. The amount of Pt required for Pt-particle/ABS was 250 times less than that required for an ABS substrate covered with Pt plating film (Pt-film/ABS). The catalytic activity for H2O2 decomposition was estimated by measuring the residual H2O2 concentration after immersing the catalyst for 360 min. The Pt-particle/ABS catalyst had a considerably higher specific catalytic activity for H2O2 decomposition than the Pt-film/ABS catalyst. In addition, sterilization performance was estimated from the initial rate of H2O2 decomposition over 60 min. The Pt-particle/ABS catalyst demonstrated a better sterilization performance than the Pt-film/ABS catalyst. The difference between Pt-particle/ABS and Pt-film/ABS was shown to reflect the size of the O2 bubbles formed during H2O2 decomposition. Full article
(This article belongs to the Special Issue Noble Metal Nanoparticles in Catalysis)
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Open AccessArticle
First-Principles Study of Structural, Electronic and Magnetic Properties of Metal-Centered Tetrahexahedral V15+ Cluster
Nanomaterials 2017, 7(7), 164; https://doi.org/10.3390/nano7070164 - 30 Jun 2017
Cited by 2
Abstract
The V-centered bicapped hexagonal antiprism structure (A), as the most stable geometry of the cationic V15+ cluster, is determined by using infrared multiple photo dissociation (IR-MPD) in combination with density functional theory computations. It is found that the A [...] Read more.
The V-centered bicapped hexagonal antiprism structure (A), as the most stable geometry of the cationic V15+ cluster, is determined by using infrared multiple photo dissociation (IR-MPD) in combination with density functional theory computations. It is found that the A structure can be stabilized by 18 delocalized 3c-2e σ-bonds on outer V3 triangles of the bicapped hexagonal antiprism surface and 12 delocalized 4c-2e σ-bonds on inner trigonal pyramidal V4 moiety, and the features are related to the strong p-d hybridization of the cluster. The total magnetic moments on the cluster are predicted to be 2.0 µB, which come mainly from the central vanadium atom. Full article
(This article belongs to the Special Issue Noble Metal Nanoparticles in Catalysis)
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Open AccessArticle
Synthesis of [email protected]@CNTs Hierarchical Structure Catalyst by Atomic Layer Deposition and Their Photocatalytic and Photoelectrochemical Activity
Nanomaterials 2017, 7(5), 97; https://doi.org/10.3390/nano7050097 - 29 Apr 2017
Cited by 8
Abstract
[email protected]@CNTs hierarchical structures were prepared by first functionalizing carbon nanotubes (CNTs) with nitric acid at 140 °C. Coating of TiO2 particles on the CNTs at 300 °C was then conducted by atomic layer deposition (ALD). After the [email protected] structure was fabricated, Pt particles [...] Read more.
[email protected]@CNTs hierarchical structures were prepared by first functionalizing carbon nanotubes (CNTs) with nitric acid at 140 °C. Coating of TiO2 particles on the CNTs at 300 °C was then conducted by atomic layer deposition (ALD). After the [email protected] structure was fabricated, Pt particles were deposited on the TiO2 surface as co-catalyst by plasma-enhanced ALD. The saturated deposition rates of TiO2 on a-CNTs were 1.5 Å/cycle and 0.4 Å/cycle for substrate-enhanced process and linear process, respectively. The saturated deposition rate of Pt on TiO2 was 0.39 Å/cycle. The photocatalytic activities of [email protected]@CNTs hierarchical structures were higher than those without Pt co-catalyst. The particle size of Pt on [email protected] was a key factor to determine the efficiency of methylene blue (MB) degradation. The [email protected]@CNTs of 2.41 ± 0.27 nm exhibited the best efficiency of MB degradation. Full article
(This article belongs to the Special Issue Noble Metal Nanoparticles in Catalysis)
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Review

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Open AccessFeature PaperReview
Hydrophobic and Hydrophilic Au and Ag Nanoparticles. Breakthroughs and Perspectives
Nanomaterials 2018, 8(1), 11; https://doi.org/10.3390/nano8010011 - 27 Dec 2017
Cited by 15
Abstract
This review provides a broad look on the recent investigations on the synthesis, characterization and physico-chemical properties of noble metal nanoparticles, mainly gold and silver nanoparticles, stabilized with ligands of different chemical nature. A comprehensive review of the available literature in this field [...] Read more.
This review provides a broad look on the recent investigations on the synthesis, characterization and physico-chemical properties of noble metal nanoparticles, mainly gold and silver nanoparticles, stabilized with ligands of different chemical nature. A comprehensive review of the available literature in this field may be far too large and only some selected representative examples will be reported here, together with some recent achievements from our group, that will be discussed in more detail. Many efforts in finding synthetic routes have been performed so far to achieve metal nanoparticles with well-defined size, morphology and stability in different environments, to match the large variety of applications that can be foreseen for these materials. In particular, the synthesis and stabilization of gold and silver nanoparticles together with their properties in different emerging fields of nanomedicine, optics and sensors are reviewed and briefly commented. Full article
(This article belongs to the Special Issue Noble Metal Nanoparticles in Catalysis)
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