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Nanomaterials
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New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis
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New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Energy and Catalysis".

Deadline for manuscript submissions: closed (30 November 2021) | Viewed by 24030

Special Issue Editor

Dr. Patricia Concepción

E-Mail Website
Guest Editor
Instituto de Tecnología Química, CSIC-UPV, Universidad Politécnica de Valencia, Av de los Naranjos s/n, 46022 Valencia, Spain
Interests: heterogeneous catalysis; in situ spectroscopy; infrared; Raman; XPS; near ambient XPS (NAP-XPS) spectroscopy; metal nanoparticles; metal cluster

Special Issue Information

Dear Colleagues,

Metal nanoparticles have attracted great interest in the field of hetereogeneous catalysis due to their size and shape-dependent chemical and physical properties that strongly influence their catalytic activity. The main challenges in the field of nano-catalysis are the control of their synthesis, comprehensive knowledge of active sites enabling a rational design of efficient catalysts, and their characterization under reaction conditions. Despite the tremendous progress in the field, several tasks concerning the dynamic behaviour of metal nanoparticles under reaction conditions, the in situ formation of active sites, and their link with its chemical reactivity remain unresolved, limiting our capability to achieve the rational design of efficient catalysts. Therefore, new strategies aimed at the identification of active sites, reaction mechanisms, and the controlled synthesis of disruptive novel catalysts are strongly required.

This Special Issue seeks to highlight the most recent results contributing to an advanced understanding of heterogeneous catalysts providing stimulating contributions in the synthesis, characterization, and catalytic application of metal nanoparticles in heterogeneous catalysis.

We kindly invite you to submit a manuscript to this Special Issue entitled “New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis”.

Potential topics include but are not limited to the following:

  • Surface science;
  • Computational modelling;
  • Reaction engineering;
  • In situ spectroscopy;
  • Mechanistic insights;
  • Kinetics of surface reactions;
  • Transient studies.

Dr. Patricia Concepción
Guest Editor

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 submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue 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. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Metal nanoparticles
  • Metal clusters
  • Heterogeneous catalysis
  • In situ spectroscopy
  • Mechanistic insights
  • Theoretical modelling.

Published Papers (10 papers)

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Research

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13 pages, 2158 KiB  
Article
Water Formation Reaction under Interfacial Confinement: Al0.25Si0.75O2 on O-Ru(0001)
by Jorge Cored, Mengen Wang, Nusnin Akter, Zubin Darbari, Yixin Xu, Burcu Karagoz, Iradwikanari Waluyo, Adrian Hunt, Dario Stacchiola, Ashley Rose Head, Patricia Concepcion, Deyu Lu and Jorge Anibal Boscoboinik
Nanomaterials 2022, 12(2), 183; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12020183 - 06 Jan 2022
Cited by 2 | Viewed by 1709
Abstract
Confined nanosized spaces at the interface between a metal and a seemingly inert material, such as a silicate, have recently been shown to influence the chemistry at the metal surface. In prior work, we observed that a bilayer (BL) silica on Ru(0001) can [...] Read more.
Confined nanosized spaces at the interface between a metal and a seemingly inert material, such as a silicate, have recently been shown to influence the chemistry at the metal surface. In prior work, we observed that a bilayer (BL) silica on Ru(0001) can change the reaction pathway of the water formation reaction (WFR) near room temperature when compared to the bare metal. In this work, we looked at the effect of doping the silicate with Al, resulting in a stoichiometry of Al0.25Si0.75O2. We investigated the kinetics of WFR at elevated H2 pressures and various temperatures under interfacial confinement using ambient pressure X-ray photoelectron spectroscopy. The apparent activation energy was lower than that on bare Ru(0001) but higher than that on the BL-silica/Ru(0001). The apparent reaction order with respect to H2 was also determined. The increased residence time of water at the surface, resulting from the presence of the BL-aluminosilicate (and its subsequent electrostatic stabilization), favors the so-called disproportionation reaction pathway (*H2O + *O ↔ 2 *OH), but with a higher energy barrier than for pure BL-silica. Full article
(This article belongs to the Special Issue New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis)
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23 pages, 7727 KiB  
Article
Liquid-Phase Hydrogenation of 1-Phenyl-1-propyne on the Pd1Ag3/Al2O3 Single-Atom Alloy Catalyst: Kinetic Modeling and the Reaction Mechanism
by Alexander V. Rassolov, Igor S. Mashkovsky, Galina N. Baeva, Galina O. Bragina, Nadezhda S. Smirnova, Pavel V. Markov, Andrey V. Bukhtiyarov, Johan Wärnå, Alexander Yu. Stakheev and Dmitry Yu. Murzin
Nanomaterials 2021, 11(12), 3286; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11123286 - 03 Dec 2021
Cited by 10 | Viewed by 2124
Abstract
This research was focused on studying the performance of the Pd1Ag3/Al2O3 single-atom alloy (SAA) in the liquid-phase hydrogenation of di-substituted alkyne (1-phenyl-1-propyne), and development of a kinetic model adequately describing the reaction kinetic being also consistent [...] Read more.
This research was focused on studying the performance of the Pd1Ag3/Al2O3 single-atom alloy (SAA) in the liquid-phase hydrogenation of di-substituted alkyne (1-phenyl-1-propyne), and development of a kinetic model adequately describing the reaction kinetic being also consistent with the reaction mechanism suggested for alkyne hydrogenation on SAA catalysts. Formation of the SAA structure on the surface of PdAg3 nanoparticles was confirmed by DRIFTS-CO, revealing the presence of single-atom Pd1 sites surrounded by Ag atoms (characteristic symmetrical band at 2046 cm−1) and almost complete absence of multiatomic Pdn surface sites (<0.2%). The catalyst demonstrated excellent selectivity in alkyne formation (95–97%), which is essentially independent of P(H2) and alkyne concentration. It is remarkable that selectivity remains almost constant upon variation of 1-phenyl-1-propyne (1-Ph-1-Pr) conversion from 5 to 95–98%, which indicates that a direct alkyne to alkane hydrogenation is negligible over Pd1Ag3 catalyst. The kinetics of 1-phenyl-1-propyne hydrogenation on Pd1Ag3/Al2O3 was adequately described by the Langmuir-Hinshelwood type of model developed on the basis of the reaction mechanism, which suggests competitive H2 and alkyne/alkene adsorption on single atom Pd1 centers surrounded by inactive Ag atoms. The model is capable to describe kinetic characteristics of 1-phenyl-1-propyne hydrogenation on SAA Pd1Ag3/Al2O3 catalyst with the excellent explanation degree (98.9%). Full article
(This article belongs to the Special Issue New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis)
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16 pages, 3080 KiB  
Article
In Situ DRIFTS-MS Methanol Adsorption Study onto Supported NiSn Nanoparticles: Mechanistic Implications in Methanol Steam Reforming
by Luis F. Bobadilla, Lola Azancot, Svetlana Ivanova, Juan J. Delgado, Francisca Romero-Sarria, Miguel A. Centeno, Anne-Cécile Roger and José A. Odriozola
Nanomaterials 2021, 11(12), 3234; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11123234 - 28 Nov 2021
Cited by 3 | Viewed by 2178
Abstract
Methanol adsorption over both supported NiSn Nps and analogous NiSn catalyst prepared by impregnation was studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to gain insights into the basis of hydrogen production from methanol steam reforming. Different intermediate species such [...] Read more.
Methanol adsorption over both supported NiSn Nps and analogous NiSn catalyst prepared by impregnation was studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to gain insights into the basis of hydrogen production from methanol steam reforming. Different intermediate species such as methoxides with different geometry (bridge and monodentate) and formate species were identified after methanol adsorption and thermal desorption. It is proposed that these species are the most involved in the methanol steam reforming reaction and the major presence of metal-support interface sites in supported NiSn Nps leads to higher production of hydrogen. On the basis of these results, a plausible reaction mechanism was elucidated through the correlation between the thermal stability of these species and the evolution of the effluent gas released. In addition, it was demonstrated that DME is a secondary product generated by condensation of methoxides over the acid sites of alumina support in an acid-catalyzed reaction. Full article
(This article belongs to the Special Issue New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis)
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18 pages, 2628 KiB  
Article
Combined Spectroscopic and Computational Study of Nitrobenzene Activation on Non-Noble Metals-Based Mono- and Bimetallic Catalysts
by Reisel Millán, María Dolores Soriano, Cristina Cerdá Moreno, Mercedes Boronat and Patricia Concepción
Nanomaterials 2021, 11(8), 2037; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11082037 - 10 Aug 2021
Cited by 5 | Viewed by 2278
Abstract
In this paper, substituted anilines are industrially obtained by direct hydrogenation of nitroaromatic compounds with molecular H2 using metals as catalysts. Previous theoretical studies proposed that the mechanism of the reaction depends on the nature of the metal used as a catalyst, [...] Read more.
In this paper, substituted anilines are industrially obtained by direct hydrogenation of nitroaromatic compounds with molecular H2 using metals as catalysts. Previous theoretical studies proposed that the mechanism of the reaction depends on the nature of the metal used as a catalyst, and that rationally designed bimetallic materials might show improved catalytic performance. Herein, we present IR spectroscopic studies of nitrobenzene interactions with monometallic Ni/SiO2, Cu/SiO2 and Pd/SiO2, and with bimetallic CuNi/SiO2 and CuPd/SiO2 catalysts, both in the absence and presence of H2, combined with density functional theory (DFT) calculations on selected bimetallic NiCu(111) and PdCu(111) models. The results obtained experimentally confirm that the reaction mechanism on non-noble metals such as Ni proceeds through N-O bond dissociation, generating nitrosobenzene intermediates, while, on noble metals, such as Pd, H-attack is necessary to activate the NO bond. Moreover, a bimetallic CuPd/SiO2 catalyst with a Pd enriched surface is prepared that exhibits an enhanced H2 dissociation ability and a particular reactivity at the boundary between the two metals. Full article
(This article belongs to the Special Issue New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis)
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18 pages, 1234 KiB  
Article
Tailoring Carbon Nanotubes to Enhance their Efficiency as Electron Shuttle on the Biological Removal of Acid Orange 10 Under Anaerobic Conditions
by Ana Rita Silva, O. Salomé G.P. Soares, M. Fernando R. Pereira, M. Madalena Alves and Luciana Pereira
Nanomaterials 2020, 10(12), 2496; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10122496 - 11 Dec 2020
Cited by 10 | Viewed by 2022
Abstract
Anaerobic treatments have been described for the biodegradation of pollutants. However, the reactions proceed slowly due to the recalcitrant nature of these compounds. Carbon nanomaterials (CNM) intermediate in, and favor, the electron transfer, accelerating the anaerobic reduction of pollutants, which act as final [...] Read more.
Anaerobic treatments have been described for the biodegradation of pollutants. However, the reactions proceed slowly due to the recalcitrant nature of these compounds. Carbon nanomaterials (CNM) intermediate in, and favor, the electron transfer, accelerating the anaerobic reduction of pollutants, which act as final electron acceptors. In the present work, different carbon nanotubes (CNT) with modified surface chemistry, namely CNT oxidized with HNO3 (CNT_HNO3) and CNT doped with nitrogen in a ball milling process (CNT_N_MB) were prepared using commercial CNT as a starting material. The new CNM were tested as redox mediators (RM), 0.1 g L−1, in the biological reduction of the azo dye, Acid Orange 10 (AO10), with an anaerobic granular sludge, over 48 h of reaction. Methane production was also assessed to verify the microorganism’s activity and the CNM’s effect on the methanogenic activity. An improvement in the biological removal of AO10 occurred with all CNM (above 90%), when compared with the control without CNM (only 32.4 ± 0.3%). The best results were obtained with CNT_N_MB, which achieved 98.2 ± 0.1% biological AO10 removal, and an 11-fold reduction rate increase. In order to confer magnetic properties to the CNM, tailored CNT were impregnated with 2% of iron-samples: CNT@2%Fe, CNT@2%Fe_N_MB, and CNT@2%Fe_HNO3. The better performance of the CNT doped with nitrogen was confirmed with CNT@2%Fe_N_MB, and the magnetic character facilitated its recovery after treatment, and did not affect its good catalytic properties. No dye removal was observed in the abiotic assays, so the removal was not due to adsorption on the CNM. Furthermore, the microorganism’s viability was maintained during the assay and methane production was not affected by the presence of the CNM. Despite the toxic character of the aromatic amines formed, detoxification was observed after the biological process with thermally treated CNT. Full article
(This article belongs to the Special Issue New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis)
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20 pages, 5319 KiB  
Article
Sterically Hindered Phosphonium Salts: Structure, Properties and Palladium Nanoparticle Stabilization
by Daria M. Arkhipova, Vadim V. Ermolaev, Vasily A. Miluykov, Aidar T. Gubaidullin, Daut R. Islamov, Olga N. Kataeva and Valentine P. Ananikov
Nanomaterials 2020, 10(12), 2457; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10122457 - 09 Dec 2020
Cited by 8 | Viewed by 2259
Abstract
A new family of sterically hindered alkyl(tri-tert-butyl) phosphonium salts (n-CnH2n+1 with n = 2, 4, 6, 8, 10, 12, 14, 16, 18, 20) was synthesized and evaluated as stabilizers for the formation of palladium nanoparticles (PdNPs), [...] Read more.
A new family of sterically hindered alkyl(tri-tert-butyl) phosphonium salts (n-CnH2n+1 with n = 2, 4, 6, 8, 10, 12, 14, 16, 18, 20) was synthesized and evaluated as stabilizers for the formation of palladium nanoparticles (PdNPs), and the prepared PdNPs, stabilized by a series of phosphonium salts, were applied as catalysts of the Suzuki cross-coupling reaction. All investigated phosphonium salts were found to be excellent stabilizers of metal nanoparticles of small catalytically active size with a narrow size distribution. In addition, palladium nanoparticles exhibited exceptional stability: the presence of phosphonium salts prevented agglomeration and precipitation during the catalytic reaction. Full article
(This article belongs to the Special Issue New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis)
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18 pages, 3882 KiB  
Article
Synergy between Ni and Co Nanoparticles Supported on Carbon in Guaiacol Conversion
by Elodie Blanco, Ana Belen Dongil and Néstor Escalona
Nanomaterials 2020, 10(11), 2199; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10112199 - 04 Nov 2020
Cited by 16 | Viewed by 2518
Abstract
Nickel-cobalt bimetallic catalysts supported on high surface area graphite with different Ni:Co ratios (3:1, 2:1 and 1:1) and the monometallic Ni and Co were prepared by wetness impregnation method. The catalysts were tested in hydrodeoxygenation (HDO) of guaiacol in the liquid phase at [...] Read more.
Nickel-cobalt bimetallic catalysts supported on high surface area graphite with different Ni:Co ratios (3:1, 2:1 and 1:1) and the monometallic Ni and Co were prepared by wetness impregnation method. The catalysts were tested in hydrodeoxygenation (HDO) of guaiacol in the liquid phase at 50 bar of H2 and 300 °C. The materials were characterized by N2 adsorption–desorption, XRD, TEM/STEM, H2-TPR, and CO-chemisorption to assess their properties and correlate them with the catalytic results. The activity was higher on the bimetallic catalysts and followed the trend NiCo2:1/G ∼ NiCo3:1/G > NiCo1:1/G > Co/G > Ni/G. Also, selectivity results showed that Ni was more active in the hydrogenation favoring cyclohexanol production from phenol, while this was inhibited on the Co-containing catalysts. Hence, the results showed that synergy was created between Ni and Co and that their interaction, properties, and catalytic performance depend on the metals’ ratio. Full article
(This article belongs to the Special Issue New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis)
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16 pages, 6607 KiB  
Article
Enhancing Methane Aromatization Performance by Reducing the Particle Size of Molybdenum Oxide
by Jing Hu, Jinghai Liu, Jinglin Liu, Yangyang Li, Peihe Li, Yin Wang, Jingqi Guan and Qiubin Kan
Nanomaterials 2020, 10(10), 1991; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10101991 - 09 Oct 2020
Cited by 2 | Viewed by 2164
Abstract
Efficient use of natural gas to produce aromatics is an attractive subject; the process requires catalysts that possess high-performance active sites to activate stable C–H bonds. Here, we report a facile synthetic strategy to modify HMCM-49 with small molybdenum oxide nanoparticles. Due to [...] Read more.
Efficient use of natural gas to produce aromatics is an attractive subject; the process requires catalysts that possess high-performance active sites to activate stable C–H bonds. Here, we report a facile synthetic strategy to modify HMCM-49 with small molybdenum oxide nanoparticles. Due to the higher sublimability of nano-MoO3 particles than commercial MoO3, they more easily enter into the channels of HMCM-49 and associate with Brønsted acid sites to form active MoCx-type species under calcination and reaction conditions. Compared with commercial MoO3 modified MCM-49, nano-MoO3 modified MCM-49 exhibits higher methane conversion (13.2%), higher aromatics yield (9.1%), and better stability for the methane aromatization reaction. Full article
(This article belongs to the Special Issue New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis)
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17 pages, 4790 KiB  
Article
Cu@Pd/C with Controllable Pd Dispersion as a Highly Efficient Catalyst for Hydrogen Evolution from Ammonia Borane
by Yanliang Yang, Ying Duan, Dongsheng Deng, Dongmi Li, Dong Sui and Xiaohan Gao
Nanomaterials 2020, 10(9), 1850; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10091850 - 16 Sep 2020
Cited by 7 | Viewed by 2357
Abstract
A series of Cu@Pd/C with different Pd contents was prepared using the galvanic reduction method to disperse Pd on the surface of Cu nanoparticles on Cu/C. The dispersion of Pd was regulated by the Cu(I) on the surface, which was introduced by pulse [...] Read more.
A series of Cu@Pd/C with different Pd contents was prepared using the galvanic reduction method to disperse Pd on the surface of Cu nanoparticles on Cu/C. The dispersion of Pd was regulated by the Cu(I) on the surface, which was introduced by pulse oxidation. The Cu2O did not react during the galvanic reduction process and restricted the Pd atoms to a specific area. The pulse oxidation method was demonstrated to be an effective process to control the oxidization degree of Cu on Cu/C and then to govern the dispersion of Pd. The catalysts were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscope (HRTEM), high angular annular dark field scanning TEM (HAADF-STEM), energy-dispersive spectroscopy (EDS) mapping, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES), and inductively coupled plasma optical emission spectrometer (ICP-OES), which were used to catalyze the hydrogen evolution from ammonia borane. The Cu@Pd/C had much higher activity than the PdCu/C, which was prepared by the impregnation method. The TOF increased as the Cu2O in Cu/C used for the preparation of Cu@Pd/C increased, and the maximum TOF was 465 molH2 min−1 molPd−1 at 298 K on Cu@Pd0.5/C-640 (0.5 wt % of Pd, 640 mL of air was pulsed during the preparation of Cu/C-640). The activity could be maintained in five continuous processes, showing the strong stability of the catalysts. Full article
(This article belongs to the Special Issue New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis)
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Review

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18 pages, 2412 KiB  
Review
Volatile Organic Compounds (VOCs) Removal from Indoor Air by Heterostructures/Composites/Doped Photocatalysts: A Mini-Review
by Alexandru Enesca and Cristina Cazan
Nanomaterials 2020, 10(10), 1965; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10101965 - 03 Oct 2020
Cited by 16 | Viewed by 3282
Abstract
The impact of volatile organic compounds (VOCs) on indoor air quality and, furthermore, on human health is still a subject of research investigations considering the large increase in forms of cancer and related diseases. VOCs can be 10 times higher in indoor air [...] Read more.
The impact of volatile organic compounds (VOCs) on indoor air quality and, furthermore, on human health is still a subject of research investigations considering the large increase in forms of cancer and related diseases. VOCs can be 10 times higher in indoor air concentrations then that of the outdoors, as a consequence of emissions from electronics, building materials and consumer goods. Direct transformation of VOCs in mineralization products seems to be an alternative to reduce indoor air contaminants. The advantage of photocatalysis implementation in indoor air treatment is given by the absence of additional chemicals (such as H2O2) and waste. The present mini-review presents a comparative study on VOCs photocatalytic removal considering the photocatalyst composition, morphology and specific surface. The sheet-like morphology seems to provide a higher number of active sites which may contribute to oxidative reactions. The insertion of materials able to increase light absorbance or to mediate the charge carrier’s transport will have a beneficial impact on the overall photocatalytic efficiency. Additionally, surface chemistry must be considered when developing photocatalysts for certain gas pollutants in order to favor molecule absorbance in the interfacial region. An energy consumption perspective is given based on the light intensity and irradiation period. Full article
(This article belongs to the Special Issue New Frontiers in Metal Nanoparticles for Heterogeneous Catalysis)
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