Special Issue "Recent Advances of Electrocatalysis in Fuel Cells"

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

Deadline for manuscript submissions: closed (31 August 2018)

Special Issue Editor

Guest Editor
Dr. Kotaro Sasaki

Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA
Website | E-Mail
Interests: electrocatalysis; fuel cells; direct energy conversion; nanotechnology; nanomaterial characterization by in situ XAS; surface modifications by electrochemical methods

Special Issue Information

Dear Colleagues,

Fuel cells are widely considered as a potentially highly-efficient and clean energy systems. Regardless of the considerable advances in recent years, technical and economic barriers still exist in developing electrocatalysts, which play an essential role in fuel cell operations. The slow kinetics of the oxygen reduction reaction (ORR) at the proton-exchange membrane fuel cell (PEMFC) cathodes, even on the best Pt catalysts, causes a significant loss in cell voltage, thereby lowering the efficiency of energy conversion in the system. As a result, high Pt loading is required in cathode electrocatalysts. Durability is also critical for fuel-cell cathodes because of the very harsh conditions under which they operate, viz., low pH, dissolved molecular oxygen, and high positive potentials. On the other hand, liquid fuels, especially methanol and ethanol, are considered as potential alternatives to hydrogen fuel in PEMFCs due to their high-energy density and the ease of their storage and transportation. However, carbon monoxide (CO) poisoning also takes place during the methanol oxidation reaction (MOR). The tardiness of MOR at the anode is more prominent than that of ORR at the cathode, adversely affecting the performance of direct methanol oxidation fuel cells (DMFCs). Ethanol is a non-toxic renewable energy source that can be be produced from agricultural products; however, the commercialization of direct ethanol oxidation fuel cells (DEFCs) is considered more difficult than that of DMFCs, because the kinetics of ethanol oxidation reaction (EOR) are slower than those of MOR, even for the best available catalysts. Further development of more-efficient electrocatalysts for both cathodes and anodes is therefore necessary. This Special Issue aims to cover the most recent advances in fuel cell electrocatalysts to alleviate the current situations/drawbacks and to provide a better understanding in the development of high-performing fuel cells.

Dr. Kotaro Sasaki
Guest Editor

Manuscript Submission Information

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Keywords

  • Proton/anion exchange membrane fuel cells
  • Direct alcohol fuel cells
  • Low Pt-group-metal (PGM) electrocatalysts
  • Non-PGM electrocatalysts
  • Oxygen reduction reaction
  • Methanol oxidation reaction
  • Ethanol oxidation reaction
  • Hydrogen oxidation reaction
  • Core-shell structures
  • Density function theory

Published Papers (3 papers)

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Research

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Open AccessArticle Investigation of Earth-Abundant Oxygen Reduction Electrocatalysts for the Cathode of Passive Air-Breathing Direct Formate Fuel Cells
Catalysts 2018, 8(8), 320; https://doi.org/10.3390/catal8080320
Received: 30 June 2018 / Revised: 26 July 2018 / Accepted: 29 July 2018 / Published: 6 August 2018
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Abstract
The development of direct formate fuel cells encounters important obstacles related to the sluggish oxygen reduction reaction (ORR) and low tolerance to formate ions in Pt-based cathodes. In this study, electrocatalysts formed by earth-abundant elements were synthesized, and their activity and selectivity for
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The development of direct formate fuel cells encounters important obstacles related to the sluggish oxygen reduction reaction (ORR) and low tolerance to formate ions in Pt-based cathodes. In this study, electrocatalysts formed by earth-abundant elements were synthesized, and their activity and selectivity for the ORR were tested in alkaline electrolyte. The results showed that carbon-encapsulated iron-cobalt alloy nanoparticles and carbon-supported metal nitrides, characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD), do not present significant activity for the ORR, showing the same half-wave potential of Vulcan carbon. Contrarily, nitrogen-doped carbon, synthesized using imidazole as the nitrogen source, showed an increase in the half-wave potential, evidencing an influential role of nitrogen in the ORR electrocatalysis. The synthesis with the combination of Vulcan, imidazole, and iron or cobalt precursors resulted in the formation of nitrogen-coordinated iron (or cobalt) moieties, inserted in a carbon matrix, as revealed by X-ray absorption spectroscopy (XAS). Steady-state polarization curves for the ORR evidenced a synergistic effect between Fe and Co when these two metals were included in the synthesis (FeCo-N-C material), showing higher activity and higher limiting current density than the materials prepared only with Fe or Co. The FeCo-N-C material presented not only the highest activity for the ORR (approaching that of the state-of-the-art Pt/C) but also high tolerance to the presence of formate ions in the electrolyte. In addition, measurements with FeCo-N-C in the cathode of an passive air-breathing direct formate fuel cells, (natural diffusion of formate), showed peak power densities of 15.5 and 10.5 mW cm−2 using hydroxide and carbonate-based electrolytes, respectively, and high stability over 120 h of operation. Full article
(This article belongs to the Special Issue Recent Advances of Electrocatalysis in Fuel Cells)
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Open AccessArticle Analysis of Anodes of Microbial Fuel Cells When Carbon Brushes Are Preheated at Different Temperatures
Catalysts 2017, 7(11), 312; https://doi.org/10.3390/catal7110312
Received: 21 September 2017 / Revised: 17 October 2017 / Accepted: 19 October 2017 / Published: 25 October 2017
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Abstract
The anode electrode is one of the most important components in all microbial electrochemical technologies (METs). Anode materials pretreatment and modification have been shown to be an effective method of improving anode performance. According to mass loss analysis during carbon fiber heating, five
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The anode electrode is one of the most important components in all microbial electrochemical technologies (METs). Anode materials pretreatment and modification have been shown to be an effective method of improving anode performance. According to mass loss analysis during carbon fiber heating, five temperatures (300, 450, 500, 600, and 750 °C) were selected as the pre-heating temperatures of carbon fiber brush anodes. Microbial fuel cell (MFC) reactors built up with these pre-heated carbon brush anodes performed with different power densities and Coulombic efficiencies (CEs). Two kinds of measuring methods for power density were applied, and the numerical values of maximum power densities diverged greatly. Reactors with 450 °C anodes, using both methods, had the highest power densities, and the highest CEs were found using 500 °C anode reactors. The surface elements of heat-treated carbon fibers were analyzed using X-ray photoelectron spectra (XPS), and C, O, and N were the main constituents of the carbon fiber. There were four forms of N1s at the surface of the polyacrylonitrile (PAN)-based carbon fiber, and their concentrations were different at different temperature samples. The microbial community of the anode surface was analyzed, and microbial species on anodes from every sample were similar. The differences in anode performance may be caused by mass loss and by the surface elements. For carbon brush anodes used in MFCs or other BESs, 450–500 °C preheating was the most suitable temperature range in terms of the power densities and CEs. Full article
(This article belongs to the Special Issue Recent Advances of Electrocatalysis in Fuel Cells)
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Review

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Open AccessReview Morphology-Controlled Nitrogen-Containing Polymers as Synthetic Precursors for Electrochemical Oxygen Reduction Fe/N/C Cathode Catalysts
Catalysts 2018, 8(8), 324; https://doi.org/10.3390/catal8080324
Received: 2 July 2018 / Revised: 26 July 2018 / Accepted: 6 August 2018 / Published: 8 August 2018
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Abstract
Nitrogen-containing aromatic polymers such as polyimide are known for their high thermal stability. While they have been widely used in industry, their relevance to catalysis is still quite limited. In recent years, nitrogen-containing polymers have been explored as precursors of nitrogen-doped carbonaceous materials,
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Nitrogen-containing aromatic polymers such as polyimide are known for their high thermal stability. While they have been widely used in industry, their relevance to catalysis is still quite limited. In recent years, nitrogen-containing polymers have been explored as precursors of nitrogen-doped carbonaceous materials, which are particularly attractive as non-precious metal catalysts for oxygen reduction in fuel cells. The high thermal stability of nitrogen-containing polymers contributes to an effective control over the morphology of the resulting carbonaceous catalysts. This review article provides an overview of the recent progress on the research and development of Fe/N/C oxygen reduction catalysts prepared from morphology-controlled nitrogen-containing polymers. Full article
(This article belongs to the Special Issue Recent Advances of Electrocatalysis in Fuel Cells)
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