Special Issue "Electro-Catalysts for Energy Conversion and Storage Devices"

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

Deadline for manuscript submissions: 30 September 2020.

Special Issue Editor

Dr. Vincenzo Baglio
Website SciProfiles
Guest Editor
CNR-ITAE Institute for Advanced Energy Technologies “N. Giordano”, Via Salita S. Lucia sopra Contesse 5, Messina 98126, Italy
Interests: polymer electrolyte fuel cells; direct alcohol fuel cells; water electrolysis; metal–air batteries; dye-sensitized solar cells; photo-electrolysis; carbon dioxide electro-reduction
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Special Issue Information

Dear Colleagues,

Today, with the threatening energy crisis and global warming, electrochemistry faces a great challenge as a discipline interfacing chemistry and electrical engineering. The efficient conversion and storage of energy are closely correlated to the development of electrochemical energy technologies, such as fuel cells, batteries and electrolyzers. Such devices are claimed to dominate the power supply market in a future sustainable energy economy. The practical efficiencies must be yet boosted before many of the aforementioned technologies become viable for large-scale use. In particular, more active, stable, and economically viable catalysts must be developed for the electrocatalytic processes occurring at practical electrodes of the cells. In this context, the research and development of efficient catalysts are key points to reach this target. This Special Issue is intended to present and discuss the most recent advances and developments in heterogeneous catalysis for application in electrochemical energy conversion and storage devices.

Dr. Vincenzo Baglio
Guest Editor

Manuscript Submission Information

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Keywords

  • Polymer Electrolyte Fuel Cells (PEFC)
  • Direct Alcohol Fuel Cells (DAFC)
  • Solid Oxide Fuel Cells (SOFC)
  • Polymer electrolyte and solid oxide electrolysers
  • Metal-air batteries
  • Advances in the design and synthesis of electrocatalysts
  • Advanced carbonaceous, non-carbonaceous, and hybrid support for electrocatalysts
  • Oxygen reduction and/or evolution reactions
  • Electro-oxidation of alcohols and other organic fuels (formic acid, glycols, etc.)
  • Hydrogen oxidation and/or evolution reactions

Published Papers (11 papers)

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Research

Open AccessArticle
X-ray Absorption Spectroscopy Investigation of Platinum–Gadolinium Thin Films with Different Stoichiometry for the Oxygen Reduction Reaction
Catalysts 2020, 10(9), 978; https://doi.org/10.3390/catal10090978 - 31 Aug 2020
Abstract
Alloys of platinum and lanthanides present a remarkable activity for the oxygen reduction reaction—both in the form of extended surfaces and nanoparticulate catalysts. Co-sputter-deposited thin film catalysts based on platinum and gadolinium show great oxygen reduction activity improvement over pure Pt. The sputter-deposition [...] Read more.
Alloys of platinum and lanthanides present a remarkable activity for the oxygen reduction reaction—both in the form of extended surfaces and nanoparticulate catalysts. Co-sputter-deposited thin film catalysts based on platinum and gadolinium show great oxygen reduction activity improvement over pure Pt. The sputter-deposition technique represents a viable and versatile approach for investigating model catalyst systems with different compositions. In this work, co-sputtered Pt5Gd and Pt7.5Gd thin films were investigated using X-ray absorption spectroscopy as well as standardized electrochemical techniques. These investigations revealed the importance of forming alloys with specific stoichiometry, supporting the need of forming compressively strained Pt overlayers in order to achieve optimum catalytic performances. Full article
(This article belongs to the Special Issue Electro-Catalysts for Energy Conversion and Storage Devices)
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Open AccessFeature PaperArticle
Low-Noble-Metal-Loading Hybrid Catalytic System for Oxygen Reduction Utilizing Reduced-Graphene-Oxide-Supported Platinum Aligned with Carbon-Nanotube-Supported Iridium
Catalysts 2020, 10(6), 689; https://doi.org/10.3390/catal10060689 - 19 Jun 2020
Cited by 2
Abstract
Hybrid systems composed of the reduced graphene oxide-supported platinum and multiwalled carbon nanotube-supported iridium (both noble metals utilized at low loadings on the level of 15 and ≤2 µg cm−2, respectively) were considered as catalytic materials for the reduction of oxygen [...] Read more.
Hybrid systems composed of the reduced graphene oxide-supported platinum and multiwalled carbon nanotube-supported iridium (both noble metals utilized at low loadings on the level of 15 and ≤2 µg cm−2, respectively) were considered as catalytic materials for the reduction of oxygen in acid media (0.5-mol dm−3 H2SO4). The electrocatalytic activity toward reduction of oxygen and formation of hydrogen peroxide intermediate are tested using rotating ring–disk electrode (RRDE) voltammetric experiments. The efficiency of the proposed catalytic systems was also addressed by performing galvanodynamic measurements with gas diffusion electrode (GDE) half-cell at 80 °C. The role of carbon nanotubes is to improve charge distribution at the electrocatalytic interface and facilitate the transport of oxygen and electrolyte in the catalytic systems by lowering the extent of reduced graphene oxide restacking during solvent evaporation. The diagnostic electrochemical experiments revealed that—in iridium-containing systems—not only higher disk currents, but also somehow smaller ring currents are produced (when compared to the Ir-free reduced graphene oxide-supported platinum), clearly implying formation of lower amounts of the undesirable hydrogen peroxide intermediate. The enhancement effect originating from the addition of traces of iridium (supported onto carbon nanotubes) to platinum, utilized at low loading, may originate from high ability of iridium to induce decomposition of the undesirable hydrogen peroxide intermediate. Full article
(This article belongs to the Special Issue Electro-Catalysts for Energy Conversion and Storage Devices)
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Open AccessFeature PaperArticle
Enhanced Photoelectrochemical Water Splitting at Hematite Photoanodes by Effect of a NiFe-Oxide co-Catalyst
Catalysts 2020, 10(5), 525; https://doi.org/10.3390/catal10050525 - 09 May 2020
Cited by 2
Abstract
Tandem photoelectrochemical cells (PECs), made up of a solid electrolyte membrane between two low-cost photoelectrodes, were investigated to produce “green” hydrogen by exploiting renewable solar energy. The assembly of the PEC consisted of an anionic solid polymer electrolyte membrane (gas separator) clamped between [...] Read more.
Tandem photoelectrochemical cells (PECs), made up of a solid electrolyte membrane between two low-cost photoelectrodes, were investigated to produce “green” hydrogen by exploiting renewable solar energy. The assembly of the PEC consisted of an anionic solid polymer electrolyte membrane (gas separator) clamped between an n-type Fe2O3 photoanode and a p-type CuO photocathode. The semiconductors were deposited on fluorine-doped tin oxide (FTO) transparent substrates and the cell was investigated with the hematite surface directly exposed to a solar simulator. Ionomer dispersions obtained from the dissolution of commercial polymers in the appropriate solvents were employed as an ionic interface with the photoelectrodes. Thus, the overall photoelectrochemical water splitting occurred in two membrane-separated compartments, i.e., the oxygen evolution reaction (OER) at the anode and the hydrogen evolution reaction (HER) at the cathode. A cost-effective NiFeOx co-catalyst was deposited on the hematite photoanode surface and investigated as a surface catalytic enhancer in order to improve the OER kinetics, this reaction being the rate-determining step of the entire process. The co-catalyst was compared with other well-known OER electrocatalysts such as La0.6Sr0.4Fe0.8CoO3 (LSFCO) perovskite and IrRuOx. The Ni-Fe oxide was the most promising co-catalyst for the oxygen evolution in the anionic environment in terms of an enhanced PEC photocurrent and efficiency. The materials were physico-chemically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Full article
(This article belongs to the Special Issue Electro-Catalysts for Energy Conversion and Storage Devices)
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Open AccessArticle
Activated Carbon/MnO2 Composites as Electrode for High Performance Supercapacitors
Catalysts 2020, 10(2), 256; https://doi.org/10.3390/catal10020256 - 20 Feb 2020
Cited by 1
Abstract
Activated carbon (AC) was synthesized with various weight ratios of manganese dioxide (MO) through a simple hydrothermal approach. The electrochemical performance of the synthesized activated carbon/MnO2 composites was investigated. The effect of the activated carbon/MnO2 (AM) ratio on the electrochemical properties [...] Read more.
Activated carbon (AC) was synthesized with various weight ratios of manganese dioxide (MO) through a simple hydrothermal approach. The electrochemical performance of the synthesized activated carbon/MnO2 composites was investigated. The effect of the activated carbon/MnO2 (AM) ratio on the electrochemical properties of the activated carbon/MnO2 composites and the pore structure was also examined. The results show that the specific capacitance of the activated carbon material has been improved after the addition of MO. The as-synthesized composite material exhibits specific capacitance of 60.3 F g−1 at 1 A g−1, as well as stable cycle performance and 99.6% capacitance retention over 5000 cycles. Full article
(This article belongs to the Special Issue Electro-Catalysts for Energy Conversion and Storage Devices)
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Open AccessArticle
Study of the Hydrogen Evolution Reaction Using Ionic Liquid/Cobalt Porphyrin Systems as Electro and Photoelectrocatalysts
Catalysts 2020, 10(2), 239; https://doi.org/10.3390/catal10020239 - 17 Feb 2020
Abstract
In this work, the design and manufacture of graphite paste (Gr) electrodes is carried out, including N-octylpyridinium hexafluorophosphate (OPyPF6) ionic liquid (IL) as binder and modification with Co-octaethylporphyrin (Co), in order to study the hydrogen evolution reaction (HER) in the [...] Read more.
In this work, the design and manufacture of graphite paste (Gr) electrodes is carried out, including N-octylpyridinium hexafluorophosphate (OPyPF6) ionic liquid (IL) as binder and modification with Co-octaethylporphyrin (Co), in order to study the hydrogen evolution reaction (HER) in the absence and presence of light. The system is characterized by XRD and FESEM-EDX (Field Emission Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy), confirming the presence of all the components of the system in the electrode surface. The studies carried out in this investigation confirm that a photoelectrocatalytic system towards HER is obtained. The system is stable, efficient and easy to prepare. Through cyclic voltammetry and electrochemical impedance spectroscopy, was determined that these electrodes improve their electrochemical and electrical properties upon the addition of OPyPF6. These effects improve even more when the systems are modified with Co porphyrin. It is also observed that when the systems are irradiated at 395 nm, the redox process is favored in energy terms, as well as in its electrical properties. Through gas chromatography, it was determined that the graphite paste electrode in the presence of ionic liquid and porphyrin (Gr/IL/Co) presents a high turnover number (TON) value (6342 and 6827 in presence of light) in comparison to similar systems reported. Full article
(This article belongs to the Special Issue Electro-Catalysts for Energy Conversion and Storage Devices)
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Open AccessArticle
A Zn-Doped Ba0.5Sr0.5Co0.8Fe0.2O3-δ Perovskite Cathode with Enhanced ORR Catalytic Activity for SOFCs
Catalysts 2020, 10(2), 235; https://doi.org/10.3390/catal10020235 - 15 Feb 2020
Cited by 3
Abstract
The insufficient oxygen reduction reaction activity of cathode materials is one of the main obstacles to decreasing the operating temperature of solid oxide fuel cells (SOFCs). Here, we report a Zn-doped perovskite oxide Ba0.5Sr0.5(Co0.8Fe0.2)0.96 [...] Read more.
The insufficient oxygen reduction reaction activity of cathode materials is one of the main obstacles to decreasing the operating temperature of solid oxide fuel cells (SOFCs). Here, we report a Zn-doped perovskite oxide Ba0.5Sr0.5(Co0.8Fe0.2)0.96Zn0.04O3-δ (BSCFZ) as the SOFC cathode, which exhibits much higher electrocatalytical activity than Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) for the oxygen reduction reaction (ORR). The BSCFZ cathode exhibited a polarization resistance of only 0.23 and 0.03 Ω·cm2 on a symmetrical cell at 600 and 750 °C, respectively. The corresponding maximum power density of 0.58 W·cm−2 was obtained in the yittria-stabilized zirconia (YSZ)-based anode-supported single cell at 750 °C, an increase by 35% in comparison to the BSCF cathode. The enhanced performance can be attributed to a better balance of oxygen vacancies, surface electron transfer and ionic mobility as promoted by the low valence Zn2+ doping. This work proves that Zn-doping is a highly effective strategy to further enhance the ORR electrocatalytic activity of state-of-the-art Ba0.5Sr0.5Co0.8Fe0.2O3-δ cathode material for intermediate temperature SOFCs. Full article
(This article belongs to the Special Issue Electro-Catalysts for Energy Conversion and Storage Devices)
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Open AccessArticle
Performance Improvement in Direct Methanol Fuel Cells by Using CaTiO3-δ Additive at the Cathode
Catalysts 2019, 9(12), 1017; https://doi.org/10.3390/catal9121017 - 02 Dec 2019
Cited by 1
Abstract
A non-stoichiometric calcium titanate CaTiO3-δ (CTO) was synthesized and used as oxygen reduction reaction co-catalyst (together with Pt/C) in direct methanol fuel cells (DMFCs). A membrane-electrode assembly (MEA), equipped with a composite cathode formulation (Pt/C:CTO1:1), was investigated in DMFC, using a 2 [...] Read more.
A non-stoichiometric calcium titanate CaTiO3-δ (CTO) was synthesized and used as oxygen reduction reaction co-catalyst (together with Pt/C) in direct methanol fuel cells (DMFCs). A membrane-electrode assembly (MEA), equipped with a composite cathode formulation (Pt/C:CTO1:1), was investigated in DMFC, using a 2 M methanol solution at the anode and oxygen at the cathode, and compared with an MEA equipped with a benchmark Pt/C cathode catalyst. It appears that the presence of the CTO additive promotes the oxygen reduction reaction (ORR) due to the presence of oxygen vacancies as available active sites for oxygen adsorption in the lattice. The increase in power density obtained with the CTO-based electrode, compared with the benchmark Pt/C, was more than 40% at 90 °C, reaching a maximum power density close to 120 mW cm−2, which is one of the highest values reported in the literature under similar operating conditions. Full article
(This article belongs to the Special Issue Electro-Catalysts for Energy Conversion and Storage Devices)
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Open AccessArticle
In-situ Quantification of Nanoparticles Oxidation: A Fixed Energy X-ray Absorption Approach
Catalysts 2019, 9(8), 659; https://doi.org/10.3390/catal9080659 - 31 Jul 2019
Abstract
The oxidation of palladium nanoparticles causes the performance degradation of alkaline direct ethanol fuel cells. Quantifying this oxidation is a task of tremendous importance to design mitigation strategies that extend the service life of catalysts and devices. Here, we show that the Fixed [...] Read more.
The oxidation of palladium nanoparticles causes the performance degradation of alkaline direct ethanol fuel cells. Quantifying this oxidation is a task of tremendous importance to design mitigation strategies that extend the service life of catalysts and devices. Here, we show that the Fixed Energy X-ray Absorption Voltammetry (FEXRAV) can provide this information with an in-situ approach. To do so, we have developed a quantification method that assumes the linear response at fixed energy. With this method, we have investigated the oxidation of carbon black-supported palladium electrocatalysts during cyclic voltammetry in the same solution employed as a fuel in the direct ethanol fuel cells. We have shown that up to 38% of the palladium is oxidised at 1.2 V vs. RHE and that such oxidation also happens at lower potentials that the catalyst can experience in real direct ethanol fuel cells. The result of this study is a proof of concept of quantitative FEXRAV. Full article
(This article belongs to the Special Issue Electro-Catalysts for Energy Conversion and Storage Devices)
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Open AccessArticle
Point-Defect-Rich Carbon Sheets as the High-Activity Catalyst Toward Oxygen Reduction and Hydrogen Evolution
Catalysts 2019, 9(4), 386; https://doi.org/10.3390/catal9040386 - 25 Apr 2019
Cited by 1
Abstract
Exploring a novel approach for the synthesis of oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) catalysts with inexpensive and high-activity is desirable. Herein, we report a bubble templating method to synthesize the graphene-like mesoporous carbon sheets with point defects as ORR/HER [...] Read more.
Exploring a novel approach for the synthesis of oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) catalysts with inexpensive and high-activity is desirable. Herein, we report a bubble templating method to synthesize the graphene-like mesoporous carbon sheets with point defects as ORR/HER bifunctional electrocatalysts. The typical product shows excellent ORR performance including the positive onset potential (740 mV) and high diffusion-limiting current density (4.07 mA cm−2). Along with small Tafel slopes, the overpotential is determined to be about −453 and −378 mV at 10 mA cm−2 in both alkaline and acidic media, which suggests a good candidate for HER reaction as well. The superior catalytic activities are derived from the abundant point defects on the mesoporous carbon sheets surface, especially the existence of pyridinic and pyrrolic nitrogen species. This study may be an alternative route to prepare the novel functional materials for the applications of ORR and HER. Full article
(This article belongs to the Special Issue Electro-Catalysts for Energy Conversion and Storage Devices)
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Open AccessArticle
Pt/C and Pt/SnOx/C Catalysts for Ethanol Electrooxidation: Rotating Disk Electrode Study
Catalysts 2019, 9(3), 271; https://doi.org/10.3390/catal9030271 - 16 Mar 2019
Cited by 7
Abstract
Pt/C and Pt/SnOx/C catalysts were synthesized using the polyol method. Their structure, morphology and chemical composition were studied using a scanning electron microscope equipped with an energy dispersive X-ray spectrometer, transition electron microscope and X-ray photoelectron spectroscope. Electrochemical measurements were based [...] Read more.
Pt/C and Pt/SnOx/C catalysts were synthesized using the polyol method. Their structure, morphology and chemical composition were studied using a scanning electron microscope equipped with an energy dispersive X-ray spectrometer, transition electron microscope and X-ray photoelectron spectroscope. Electrochemical measurements were based on the results of rotating disk electrode (RDE) experiments applied to ethanol electrooxidation. The quick evaluation of catalyst activity, electrochemical behavior, and an average number of transferred electrons were made using the RDE technique. The usage of SnOx (through the carbon support modification) in a binary system together with Pt causes a significant increase of the catalyst activity in ethanol oxidation reaction and the utilization of ethanol. Full article
(This article belongs to the Special Issue Electro-Catalysts for Energy Conversion and Storage Devices)
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Open AccessArticle
Comparative Study between Pristine Ag and Ag Foam for Electrochemical Synthesis of Syngas with Carbon Dioxide and Water
Catalysts 2019, 9(1), 57; https://doi.org/10.3390/catal9010057 - 08 Jan 2019
Cited by 2
Abstract
The electrosynthesis of syngas (H2 + CO) from CO2 and H2O can reduce greenhouse gas emissions and address the energy crisis. In the present work, silver (Ag) foam was employed as a catalytic electrode for the electrochemical reduction of [...] Read more.
The electrosynthesis of syngas (H2 + CO) from CO2 and H2O can reduce greenhouse gas emissions and address the energy crisis. In the present work, silver (Ag) foam was employed as a catalytic electrode for the electrochemical reduction of CO2 in aqueous solution to design different syngas ratios (H2:CO). In addition to H2 and CO, a small amount of formic acid was found in the liquid phase. By contrast, the planar polycrystalline Ag yields CO, formic acid, methane and methanol as the carbon-containing products. During the potential-controlled electrolysis, the Ag foam displayed a relatively higher activity and selectivity in the electroreduction of aqueous CO2 to CO compared with its smooth surface counterpart, as evidenced by the lower onset potential, higher partial current density and Faradic efficiency at the same bias voltage. Moreover, the electrode remained stable after three successive cycles. Based on the characterization using X-ray diffraction, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, potential step determination and density functional theory calculations, superior performance was credited to the three-dimensional structure of Ag foam constructed with coral-like Ag particles, in which the numerous edge sites are beneficial for the stabilization of the surface adsorbed COOH species and the exposed {111} facets favor the desorption of adsorbed CO species. Full article
(This article belongs to the Special Issue Electro-Catalysts for Energy Conversion and Storage Devices)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: X-ray Absorption Spectroscopy Investigation of Platinum-Gadolinium Thin Films with Different Stoichiometry for the Oxygen Reduction Reaction
Authors: K. D. Jensen1,2, A. F. Pedersen2, E. Zamburlini2 and I. E. L. Stephens2,3, I. Chorkendorff2, and M. Escudero-Escribano1,2,*
Affiliation: 1 University of Copenhagen 2 Technical University of Denmark 3 Imperial College London
Abstract: Alloys of platinum and lanthanides present a remarkable activity for the oxygen reduction reaction, both in the form of extended surfaces and nanoparticulate catalysts. Co-sputter deposited thin film catalysts based on platinum and gadolinium show great oxygen reduction activity improvement over pure Pt. The sputter deposition technique represents a viable and versatile approach for investigating model catalyst systems with different compositions. In this work, co-sputtered Pt5Gd and Pt7.5Gd thin films were investigated using X-ray absorption spectroscopy as well as standardised electrochemical techniques. These investigations revealed the importance of forming alloys with specific stoichiometry, supporting the need of forming compressively strained Pt overlayers in order to achieve optimum catalytic performances.

Title: Low-Noble-Metal-Loading Hybrid Catalytic System for Oxygen Reduction Utilizing Reduced-Graphene-Oxide-Supported-Platinum Aligned with Carbon-Nanotube-Supported Iridium
Authors: Beata Dembinska1, Magdalena Modzelewska1, Agnieszka Zlotorowicz1,5, Krzysztof Miecznikowski1, Leszek Stobinski1,2, Artur Malolepszy2, Maciej Krzywiecki3, Jerzy Żak1,4, Enrico Negro5, Vito Di Noto5, Pa
Affiliation:1Faculty of Chemistry, University of Warsaw, Pasteura 1, PL-02-093 Warsaw, Poland; 2Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warynskiego 1, Warsaw, Poland; 3Institute of Physics–CSE, Silesian University of Technology, Konarskiego 22B, 44-100 Gliwice, Poland; 4Silesian University of Technology, Faculty of Chemistry, Strzody 9, 44-100 Gliwice, Poland; 5Department of Industrial Engineering, Università degli Studi di Padova in Department of Chemical Sciences, Via Marzolo 1, 35131 Padova (PD) Italy

Title: Electrocatalysis for Oxygen Reduction Reaction on EDTAFeNa and Melamine co-Derived self-Supported Fe-N-C Materials
Authors: Xiang-Hui Yan,, Ziwei Meng, Mengfan Shen, Dong Li, Hongfang Shen
Affiliation: School of Materials Science and Engineering, North Minzu University, Yinchuan, Ningxia 750021, China ; International Scientific & Technological Cooperation Base of Industrial Waste Recycling and Advanced Materials, North Minzu University, Yinchuan, Ningxia 750021, China
Abstract: Self-supported Fe-N-C materials were prepared by carbonization of dual precursors including EDTA ferric sodium (EDTAFeNa) and melamine (MA) followed by acid-leaching and final pyrolysis. Towards oxygen reduction reaction (ORR) in 0.1 M KOH, the as-prepared MA/EDTAFeNa-AL-HT2 delivered onset (Eonset) and half-wave (E1/2) potentials of 0.97 and 0.84 V vs RHE, respectively, identical with that of a state-of-the-art Pt/C catalyst, accompanied with predominantly 4-electron pathway. The introduction of MA and extension of acid-leaching promoted a positive shift of E1/2 for 50 mV relative to that for only EDTAFeNa-derived counterpart. It is revealed that the enhancement of ORR activity is attributed to increase of nitrogen content and decrease of magnetic Fe species whilst nearly excluding effects of the graphitization degree, configuration of iron species and mesoscopic structure.

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