Special Issue "Platinum-Free Electrocatalysts"

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Electrocatalysis".

Deadline for manuscript submissions: closed (30 September 2018)

Special Issue Editors

Guest Editor
Prof. Dr. Massimo Innocenti

Department of Chemistry, Università di Firenze, Via della Lastruccia 3-13, 50019 Sesto Fiorentino, Firenze, Italy
Website | E-Mail
Interests: electrodeposition; energy; electrocatalysis; fuel cells
Guest Editor
Dr. Francesco Vizza

Institute of Chemistry of Organometallic Compounds, ICCOM-CNR, Polo Scientifico Area CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy
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Interests: electrocatalysis; fuel cells; electrolysis; hydrogen; CO2 electroreduction
Guest Editor
Dr. Hamish Miller

Institute of Chemistry of Organometallic Compounds, ICCOM-CNR, Polo Scientifico Area CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy
Website | E-Mail
Interests: electrocatalysis; fuel cells; electrolysis; hydrogen; CO2 electroreduction

Special Issue Information

Dear Colleagues,

Replacing rare and costly platinum (Pt)-based catalysts with abundant and sustainable non-precious-metal alternatives for fuel cells and metal air batteries will be essential for the wider diffusion, in the future, of such devices. At the same time, fundamental research is necessary aimed at reducing the amount of noble metals used by the combination of two or three different transition metals that promote synergic catalytic enhancements. The aim of this Special Issue is to bring together researchers from all over the world in an effort to create a summary of the state-of-the-art in recent developments in our understanding of the science and technology of platinum-free electrocatalysts. In particular, the topics of interest include a very large area of catalysts in different fields of chemistry, theoretical chemistry, energy, and all fields of morphological and structural analysis of modified surfaces of catalytic interest.

Prof. Dr. Massimo Innocenti
Dr. Francesco Vizza
Dr. Hamish Miller
Guest Editors

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Keywords

  • Electrocatalysis
  • Pt-free
  • Energy
  • Nanomaterials
  • Fuel cells
  • Metal air batteries

Published Papers (7 papers)

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Research

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Open AccessCommunication Exfoliated Molybdenum Disulfide Encapsulated in a Metal Organic Framework for Enhanced Photocatalytic Hydrogen Evolution
Catalysts 2019, 9(1), 89; https://doi.org/10.3390/catal9010089
Received: 19 November 2018 / Revised: 20 December 2018 / Accepted: 13 January 2019 / Published: 16 January 2019
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Abstract
An exfoliated MoS2 encapsulated into metal-organic frameworks (MOFs) was fabricated as a promising noble-metal-free photocatalyst for hydrogen production under visible light irradiation. The as-synthesized samples were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron [...] Read more.
An exfoliated MoS2 encapsulated into metal-organic frameworks (MOFs) was fabricated as a promising noble-metal-free photocatalyst for hydrogen production under visible light irradiation. The as-synthesized samples were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) surface analysis. It is well known that bulk MoS2 is unsuitable for photocatalysis due to its inadequate reduction and oxidation capabilities. However, exfoliated MoS2 exhibits a direct band gap of 2.8 eV due to quantum confinement, which enables it to possess suitable band positions and retain a good visible-light absorption ability. As a result, it is considered to be an encouraging candidate for photocatalytic applications. Encapsulating exfoliated MoS2 into MOF demonstrates an improved visible light absorption ability compared to pure MOF, and the highest hydrogen production rate that the encapsulated exfoliated MoS2 could reach was 68.4 μmol h-1g-1, which was much higher than that of pure MOF. With a suitable band structure and improved light-harvesting ability, exfoliated MoS2@MOF could be a potential photocatalyst for hydrogen production. Full article
(This article belongs to the Special Issue Platinum-Free Electrocatalysts)
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Open AccessArticle Sol-Gel Mediated Greener Synthesis of γ-Fe2O3 Nanostructures for the Selective and Sensitive Determination of Uric Acid and Dopamine
Catalysts 2018, 8(11), 512; https://doi.org/10.3390/catal8110512
Received: 30 September 2018 / Revised: 22 October 2018 / Accepted: 30 October 2018 / Published: 2 November 2018
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Abstract
Novel eco-freindly benign morphology-controlled biosynthesis of acicular iron oxide (γ-Fe2O3) nanostructures with various shapes and sizes have been synthesized through greener surfactant, Aloe vera (AV) extract assisted sol-gel method. By simply varying the experimental parameters, pure phase of cubic [...] Read more.
Novel eco-freindly benign morphology-controlled biosynthesis of acicular iron oxide (γ-Fe2O3) nanostructures with various shapes and sizes have been synthesized through greener surfactant, Aloe vera (AV) extract assisted sol-gel method. By simply varying the experimental parameters, pure phase of cubic spinel superparamagnetic γ-Fe2O3 nanospherical aggregates, nanobelts and nanodots have been developed. The synthesized γ-Fe2O3 nanostructures are characterized through X-Ray Diffractommetry (XRD), X-Ray Photoelectron Spectroscopy (XPS), Fourier Transform-Infrared Spectrsocopy (FT-IR), Field Emission-Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometer (VSM). Moreover, the electrochemical determination of uric acid (UA) and dopamine (DA) of the as obtained γ-Fe2O3 nanostructures are systematically demonstrated. The electrochemical properties of the γ-Fe2O3 nanostructures modified glassy carbon electrode (GCE) displayed an excellent sensing capability for the determination of DA and UA, simultaneously than the bare GCE. When compared with the other iron oxide nanostructures, γ-Fe2O3 nanobelts/GCE exhibited remarkable oxidation current response towards the biomolecules. This occurred due to the high surface area and the unique one-dimensional nanostructure of γ-Fe2O3 nanobelts. Ultimately, the greener synthesis protocol explored in this research work may also be expanded for the preparation of other morphology controlled magnetic and non-magnetic nanomaterials, which could easily open up innovative potential avenues for the development of practical biosensors. Full article
(This article belongs to the Special Issue Platinum-Free Electrocatalysts)
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Open AccessArticle Atmospheric Air Plasma Treated SnS Films: An Efficient Electrocatalyst for HER
Catalysts 2018, 8(10), 462; https://doi.org/10.3390/catal8100462
Received: 10 September 2018 / Revised: 12 October 2018 / Accepted: 15 October 2018 / Published: 17 October 2018
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Abstract
Here, we demonstrate the enhanced water-splitting performance (I = 10 mA/cm2, Tafel slope = 60 mV/dec, onset potential = −80 mV) of atmospheric air plasma treated (AAPT) SnS thin films by the hydrogen evolution reaction (HER). The as prepared SnS films [...] Read more.
Here, we demonstrate the enhanced water-splitting performance (I = 10 mA/cm2, Tafel slope = 60 mV/dec, onset potential = −80 mV) of atmospheric air plasma treated (AAPT) SnS thin films by the hydrogen evolution reaction (HER). The as prepared SnS films were subjected to Atmospheric Air Plasma Treatment (AAPT) which leads to formation of additional phases of Sn and SnO2 at plasma powers of 150 W and 250 W, respectively. The AAPT treatment at 150 W leads to the evaporation of the S atoms as SO2 generates a number of S-vacancies and Sn active edge sites over the surface of the SnS thin film. S-vacancies also create Sn active edge sites, surface p-type pinning that tunes the suitable band positions, and a hydrophilic surface which is beneficial for hydrogen adsorption/desorption. At high plasma power (250 W), the surface of the SnS films becomes oxidized and degrades the HER performance. These results demonstrate that AAPT (150 W) is capable of improving the HER performance of SnS thin films and our results indicate that SnS thin films can work as efficient electrocatalysts for HER. Full article
(This article belongs to the Special Issue Platinum-Free Electrocatalysts)
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Open AccessArticle The Preparation of Pd/Foam-Ni Electrode and Its Electrocatalytic Hydrodechlorination for Monochlorophenol Isomers
Catalysts 2018, 8(9), 378; https://doi.org/10.3390/catal8090378
Received: 21 August 2018 / Revised: 1 September 2018 / Accepted: 3 September 2018 / Published: 5 September 2018
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Abstract
Noble metal palladium modified foamed nickel electrode (Pd/foam-Ni) was prepared by electrodeposition method. The fabricated electrode showed better catalytic performance than the Pd/foam-Ni prepared by conventional electroless deposition. The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy [...] Read more.
Noble metal palladium modified foamed nickel electrode (Pd/foam-Ni) was prepared by electrodeposition method. The fabricated electrode showed better catalytic performance than the Pd/foam-Ni prepared by conventional electroless deposition. The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Electrocatalytic activity of the Pd/Ni was studied for the hydrodechlorination of monochlorophenol isomers. The Pd/Ni exhibited good catalytic activity for 3-chlorophenol (3-CP). Complete decomposition of chlorophenol isomers could be achieved within 2 h, and the hydrodechlorination process conformed to the pseudo-first-order kinetic model. It showed a supreme stability after recycling for 5 times. The Pd/Ni exhibited a promising application prospect with high effectiveness and low Pd loading. Full article
(This article belongs to the Special Issue Platinum-Free Electrocatalysts)
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Open AccessArticle The Effects of Coordinated Molecules of Two Gly-Schiff Base Copper Complexes on Their Oxygen Reduction Reaction Performance
Catalysts 2018, 8(4), 156; https://doi.org/10.3390/catal8040156
Received: 23 March 2018 / Revised: 8 April 2018 / Accepted: 10 April 2018 / Published: 12 April 2018
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Abstract
In this study, two simple Schiff base copper complexes [Cu(H2O)2(HL)]·2H2O (Complex 1) (H3L = 2-OH-4-(OH)-C6H2CH=NCH2CO2H) and [Cu(py)2(HL)] (Complex 2) (Py = pyridine) were [...] Read more.
In this study, two simple Schiff base copper complexes [Cu(H2O)2(HL)]·2H2O (Complex 1) (H3L = 2-OH-4-(OH)-C6H2CH=NCH2CO2H) and [Cu(py)2(HL)] (Complex 2) (Py = pyridine) were initially achieved and authenticated by single-crystal X-ray structure analyses (SXRD), powder X-ray diffraction analyses (PXRD), FT-IR spectroscopy, and elemental analyses. The SXRD reveals that the Cu2+ center in Complex 1 exhibited a distorted square pyramidal geometry, which is constructed based on phenolate oxygen, water molecules, carboxylate oxygen, and imine nitrogen from a deprotonated H3L ligand in an NO4 fashion. The Cu2+ atom in Complex 2 had distorted square pyramidal geometry, and was coordinated with two pyridine molecules and one Gly-Schiff base ligand, exhibiting an N3O2 binding set. Additionally, the free water molecules in Complex 1 linked independent copper complexes by intermolecular hydrogen bond to form a 2D framework. However, the one-dimensional chain supramolecular structure of Complex 2 was formed by the intermolecular O–H…O hydrogen bonds. The oxygen reduction performance of the two complexes was analyzed by cyclic voltammetry (CV) and the rotating disk electrode (RDE) method. Both complexes could catalyze the conversion of oxygen to water through a predominant four-electron pathway, and the Cu–NxOy moieties might be the functional moieties for the catalytic activity. The catalytic pathways and underlying mechanisms are also discussed in detail, from which the structure–activity relationship of the complexes was obtained. Full article
(This article belongs to the Special Issue Platinum-Free Electrocatalysts)
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Open AccessArticle Carbon-Supported Copper-Based Nitrogen-Containing Supramolecule as an Efficient Oxygen Reduction Reaction Catalyst in Neutral Medium
Catalysts 2018, 8(2), 53; https://doi.org/10.3390/catal8020053
Received: 19 December 2017 / Revised: 23 January 2018 / Accepted: 26 January 2018 / Published: 30 January 2018
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Abstract
In this work, a nitrogen-containing bidentate ligand named 5,5′-(9-octyl-9H-carbazole-2,7-diyl)bis(1,10-phenanthroline) (OCBP) was synthesized as a nitrogen precursor for making an oxygen reduction catalyst. The 1,10-phenanthroline unit provides a coordination site for copper ions, and the resulting Cu-Nx unit may be responsible for the [...] Read more.
In this work, a nitrogen-containing bidentate ligand named 5,5′-(9-octyl-9H-carbazole-2,7-diyl)bis(1,10-phenanthroline) (OCBP) was synthesized as a nitrogen precursor for making an oxygen reduction catalyst. The 1,10-phenanthroline unit provides a coordination site for copper ions, and the resulting Cu-Nx unit may be responsible for the catalytic activities of the catalyst. Carbon black was selected as a support to improve the electroconductibility of the resulting catalyst. The metallo-supramolecule (Cu-SOCBP) was dispersed on the surface of Vulcan XC-72 carbon and was used as a catalyst (designated as Cu-SOCBP/C) for the oxygen reduction reaction (ORR). The microscope structure and surface components of the catalyst were acquired via scanning electron microscopy and X-ray photoelectron spectroscopy, as well as X-ray powder diffraction. The electrochemical property and ORR mechanism of Cu-SOCBP/C were analyzed using a variety of electroanalytical methods including cyclic voltammetry, electrochemical impedance spectroscopy, and linear sweep voltammetry. These results show that Cu-SOCBP/C was successfully synthesized and that ORR was achieved mainly via a four-electron transfer process to water. Thus, Cu-SOCBP/C was an effective catalyst and might have potential application as a cathodic catalyst in microbial fuel cells, which operate in an aqueous medium. Full article
(This article belongs to the Special Issue Platinum-Free Electrocatalysts)
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Review

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Open AccessReview Methanol-Tolerant M–N–C Catalysts for Oxygen Reduction Reactions in Acidic Media and Their Application in Direct Methanol Fuel Cells
Catalysts 2018, 8(12), 650; https://doi.org/10.3390/catal8120650
Received: 7 November 2018 / Revised: 3 December 2018 / Accepted: 7 December 2018 / Published: 11 December 2018
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Abstract
Direct methanol fuel cells (DMFCs) are emerging technologies for the electrochemical conversion of the chemical energy of a fuel (methanol) directly into electrical energy, with a low environmental impact and high efficiency. Yet, before this technology can reach a large-scale diffusion, specific issues [...] Read more.
Direct methanol fuel cells (DMFCs) are emerging technologies for the electrochemical conversion of the chemical energy of a fuel (methanol) directly into electrical energy, with a low environmental impact and high efficiency. Yet, before this technology can reach a large-scale diffusion, specific issues must be solved, in particular, the high cost of the cell components. In a direct methanol fuel cell system, high capital costs are mainly derived from the use of noble metal catalysts; therefore, the development of low-cost electro-catalysts, satisfying the target requirements of high performance and durability, represents an important challenge. The research is currently addressed to the development of metal–nitrogen–carbon (M–N–C) materials as cheap and sustainable catalysts for the oxygen reduction reaction (ORR) in an acid environment, for application in polymer electrolyte fuel cells fueled by hydrogen or alcohol. In particular, this mini-review summarizes the recent advancements achieved in DMFCs using M–N–C catalysts. The presented analysis is restricted to M–N–C catalysts mounted at the cathode of a DMFC or investigated in rotating disk electrode (RDE) configuration for the ORR in the presence of methanol in order to study alcohol tolerance. The main synthetic routes and characteristics of the catalysts are also presented. Full article
(This article belongs to the Special Issue Platinum-Free Electrocatalysts)
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