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Abstract
Homogeneous electrocatalysis has been well studied over the past several decades for the conversion of small molecules to useful products for green energy applications or as chemical feedstocks. However, in order for these catalyst systems to be used in industrial applications, their activity and stability must be improved. In naturally occurring enzymes, redox equivalents (electrons, often in a concerted manner with protons) are delivered to enzyme active sites by small molecules known as redox mediators (RMs). Inspired by this, co-electrocatalytic systems with homogeneous catalysts and RMs have been developed for the conversion of alcohols, nitrogen, unsaturated organic substrates, oxygen, and carbon dioxide. In these systems, the RMs have been shown to both increase the activity of the catalyst and shift selectivity to more desired products by altering catalytic cycles and/or avoiding high-energy intermediates. However, the area is currently underdeveloped and requires additional fundamental advancements in order to become a more general strategy. Here, we summarize the recent examples of homogeneous co-electrocatalysis and discuss possible future directions for the field.
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Affiliation(s)
- Amelia G Reid
- Department of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, Virginia 22904-4319, United States
| | - Charles W Machan
- Department of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, Virginia 22904-4319, United States
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Application of a TEMPO-Polypyrrole Polymer for NOx-Mediated Oxygen Electroreduction. Catalysts 2022. [DOI: 10.3390/catal12111466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The oxygen reduction reaction (ORR) is one of the key processes for electrochemical energy storage, such as the cathode process in fuel cells and metal–air batteries. To date, the efficiency of the ORR half-reaction limits the overall performance of these energy storage devices. Traditional platinum-based materials are expensive and cannot provide the desired ORR efficiency. As an alternative, a new catalytic scheme for an ORR was proposed, which consisted of an electrode modified with a TEMPO-containing conductive polymer and a solution redox mediator system based on nitrogen oxides (NOx). NOx is perfect for oxygen reduction in solution, which, however, cannot be efficiently reduced onto a pristine electrode, while TEMPO is inactive in the ORR itself but catalyzes the electrochemical reduction of NO2 on the electrode surface. Together, these catalysts have a synergistic effect, enabling an efficient ORR in an acidic medium. In the present study, the synthesis of a novel TEMPO-containing conductive polymer and its application in the synergistic ORR system with a NOx mediator is described. The proposed mediator system may increase the performance of proton-exchange fuel cells and metal–air batteries.
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Preger Y, Johnson MR, Biswas S, Anson CW, Root TW, Stahl SS. Anthraquinone-Mediated Fuel Cell Anode with an Off-Electrode Heterogeneous Catalyst Accessing High Power Density when Paired with a Mediated Cathode. ACS ENERGY LETTERS 2020; 5:1407-1412. [PMID: 32856004 PMCID: PMC7447196 DOI: 10.1021/acsenergylett.0c00631] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The development of processes for electrochemical energy conversion and chemical production could benefit from new strategies to interface chemical redox reactions with electrodes. Here, we employ a diffusible low-potential organic redox mediator, 9,10-anthraquinone-2,7-disulfonic acid (AQDS), to promote efficient electrochemical oxidation of H2 at an off-electrode heterogeneous catalyst. This unique approach to integrate chemical and electrochemical redox processes accesses power densities up to 228 mW/cm2 (528 mW/cm2 with iR-correction). These values are significantly higher than those observed in previous mediated electrochemical H2 oxidation methods, including those using enzymes or inorganic mediators. The approach described herein shows how traditional catalytic chemistry can be coupled to electrochemical devices.
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Affiliation(s)
- Yuliya Preger
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI-53706, USA
| | - Mathew R. Johnson
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI-53706, USA
| | - Sourav Biswas
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI-53706, USA
| | - Colin W. Anson
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI-53706, USA
| | - Thatcher W. Root
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI-53706, USA
| | - Shannon S. Stahl
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI-53706, USA
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Anson CW, Stahl SS. Mediated Fuel Cells: Soluble Redox Mediators and Their Applications to Electrochemical Reduction of O 2 and Oxidation of H 2, Alcohols, Biomass, and Complex Fuels. Chem Rev 2020; 120:3749-3786. [PMID: 32216295 PMCID: PMC7357856 DOI: 10.1021/acs.chemrev.9b00717] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mediated fuel cells are electrochemical devices that produce power in a manner similar to that of conventional proton exchange membrane fuel cells (PEMFCs). They differ from PEMFCs in their use of redox mediators dissolved in liquid electrolyte to conduct oxidation of the fuel or reduction of the oxidant, typically O2, in bulk solution. The mediators transport electrons (and often protons) between the electrode and the catalysts or chemical reagents in solution. This strategy can help overcome many of the challenges associated with conventional fuel cells, including managing complex multiphase reactions (as in O2 reduction) or the use of challenging or heterogeneous fuels, such as hydrocarbons, polyols, and biomass. Mediators are also commonly used in enzymatic fuel cells, where direct electron transfer from the electrode to the enzymatic active site can be slow. This review provides a comprehensive survey of historical and recent mediated fuel cell efforts, including applications using chemical and enzymatic catalysts.
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Affiliation(s)
- Colin W. Anson
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Shannon S. Stahl
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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Han SB, Kwak DH, Park HS, Choi IA, Park JY, Kim SJ, Kim MC, Hong S, Park KW. High-Performance Chemically Regenerative Redox Fuel Cells Using a NO 3- /NO Regeneration Reaction. Angew Chem Int Ed Engl 2017; 56:2893-2897. [PMID: 28157264 DOI: 10.1002/anie.201610738] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Indexed: 11/11/2022]
Abstract
In this study, we proposed high-performance chemically regenerative redox fuel cells (CRRFCs) using NO3- /NO with a nitrogen-doped carbon-felt electrode and a chemical regeneration reaction of NO to NO3- via O2 . The electrochemical cell using the nitrate reduction to NO at the cathode on the carbon felt and oxidation of H2 as a fuel at the anode showed a maximal power density of 730 mW cm-2 at 80 °C and twofold higher power density of 512 mW cm-2 at 0.8 V, than the target power density of 250 mW cm-2 at 0.8 V in the H2 /O2 proton exchange membrane fuel cells (PEMFCs). During the operation of the CRRFCs with the chemical regeneration reactor for 30 days, the CRRFCs maintained 60 % of the initial performance with a regeneration efficiency of about 92.9 % and immediately returned to the initial value when supplied with fresh HNO3 .
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Affiliation(s)
- Sang-Beom Han
- Department of Chemical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul, 06978, Republic of Korea
| | - Da-Hee Kwak
- Department of Chemical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul, 06978, Republic of Korea
| | - Hyun Suk Park
- Department of Chemical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul, 06978, Republic of Korea
| | - In-Ae Choi
- Department of Chemical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul, 06978, Republic of Korea
| | - Jin-Young Park
- Department of Chemical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul, 06978, Republic of Korea
| | - Si-Jin Kim
- Department of Chemical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul, 06978, Republic of Korea
| | - Min-Cheol Kim
- Department of Chemical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul, 06978, Republic of Korea
| | - Seongho Hong
- Department of Chemical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul, 06978, Republic of Korea
| | - Kyung-Won Park
- Department of Chemical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul, 06978, Republic of Korea
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Han SB, Kwak DH, Park HS, Choi IA, Park JY, Kim SJ, Kim MC, Hong S, Park KW. High-Performance Chemically Regenerative Redox Fuel Cells Using a NO3
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/NO Regeneration Reaction. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201610738] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sang-Beom Han
- Department of Chemical Engineering; Soongsil University; 369 Sangdo-ro, Dongjak-gu Seoul 06978 Republic of Korea
| | - Da-Hee Kwak
- Department of Chemical Engineering; Soongsil University; 369 Sangdo-ro, Dongjak-gu Seoul 06978 Republic of Korea
| | - Hyun Suk Park
- Department of Chemical Engineering; Soongsil University; 369 Sangdo-ro, Dongjak-gu Seoul 06978 Republic of Korea
| | - In-Ae Choi
- Department of Chemical Engineering; Soongsil University; 369 Sangdo-ro, Dongjak-gu Seoul 06978 Republic of Korea
| | - Jin-Young Park
- Department of Chemical Engineering; Soongsil University; 369 Sangdo-ro, Dongjak-gu Seoul 06978 Republic of Korea
| | - Si-Jin Kim
- Department of Chemical Engineering; Soongsil University; 369 Sangdo-ro, Dongjak-gu Seoul 06978 Republic of Korea
| | - Min-Cheol Kim
- Department of Chemical Engineering; Soongsil University; 369 Sangdo-ro, Dongjak-gu Seoul 06978 Republic of Korea
| | - Seongho Hong
- Department of Chemical Engineering; Soongsil University; 369 Sangdo-ro, Dongjak-gu Seoul 06978 Republic of Korea
| | - Kyung-Won Park
- Department of Chemical Engineering; Soongsil University; 369 Sangdo-ro, Dongjak-gu Seoul 06978 Republic of Korea
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Skyllas-Kazacos M, Cao L, Kazacos M, Kausar N, Mousa A. Vanadium Electrolyte Studies for the Vanadium Redox Battery-A Review. CHEMSUSCHEM 2016; 9:1521-43. [PMID: 27295523 DOI: 10.1002/cssc.201600102] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 04/05/2016] [Indexed: 05/07/2023]
Abstract
The electrolyte is one of the most important components of the vanadium redox flow battery and its properties will affect cell performance and behavior in addition to the overall battery cost. Vanadium exists in several oxidation states with significantly different half-cell potentials that can produce practical cell voltages. It is thus possible to use the same element in both half-cells and thereby eliminate problems of cross-contamination inherent in all other flow battery chemistries. Electrolyte properties vary with supporting electrolyte composition, state-of-charge, and temperature and this will impact on the characteristics, behavior, and performance of the vanadium battery in practical applications. This Review provides a broad overview of the physical properties and characteristics of the vanadium battery electrolyte under different conditions, together with a description of some of the processing methods that have been developed to produce vanadium electrolytes for vanadium redox flow battery applications.
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Affiliation(s)
- Maria Skyllas-Kazacos
- School of Chemical Engineering, University of NSW, UNSW Australia, Sydney, 2052, Australia.
| | - Liuyue Cao
- School of Chemical Engineering, University of NSW, UNSW Australia, Sydney, 2052, Australia
| | - Michael Kazacos
- School of Chemical Engineering, University of NSW, UNSW Australia, Sydney, 2052, Australia
| | - Nadeem Kausar
- School of Chemical Engineering, University of NSW, UNSW Australia, Sydney, 2052, Australia
| | - Asem Mousa
- School of Chemical Engineering, University of NSW, UNSW Australia, Sydney, 2052, Australia
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Gerken J, Stahl SS. High-Potential Electrocatalytic O2 Reduction with Nitroxyl/NO x Mediators: Implications for Fuel Cells and Aerobic Oxidation Catalysis. ACS CENTRAL SCIENCE 2015; 1:234-43. [PMID: 27162977 PMCID: PMC4827547 DOI: 10.1021/acscentsci.5b00163] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Indexed: 05/08/2023]
Abstract
Efficient reduction of O2 to water is a central challenge in energy conversion and many aerobic oxidation reactions. Here, we show that the electrochemical oxygen reduction reaction (ORR) can be achieved at high potentials by using soluble organic nitroxyl and nitrogen oxide (NO x ) mediators. When used alone, neither organic nitroxyls, such as 2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl (TEMPO), nor NO x species, such as sodium nitrite, are effective ORR mediators. The combination of nitroxyl/NO x species, however, mediates sustained O2 reduction with overpotentials as low as 300 mV in acetonitrile containing trifluoroacetic acid. Mechanistic analysis of the coupled redox reactions supports a process in which the nitrogen oxide catalyst drives aerobic oxidation of a nitroxyl mediator to an oxoammonium species, which then is reduced back to the nitroxyl at the cathode. The electrolysis potential is dictated by the oxoammonium/nitroxyl reduction potential. The overpotentials accessible with this ORR system are significantly lower than widely studied molecular metal-macrocycle ORR catalysts and benefit from the mechanism-based specificity for four-electron reduction of oxygen to water mediated by NO x species, together with kinetically efficient reduction of oxidized NO x species by TEMPO and other organic nitroxyls.
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Tolmachev YV, Vorotyntsev MA. Fuel cells with chemically regenerative redox cathodes (review). RUSS J ELECTROCHEM+ 2014. [DOI: 10.1134/s1023193514020050] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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An L, Zhao TS, Zhou XL, Wei L, Yan XH. A high-performance ethanol–hydrogen peroxide fuel cell. RSC Adv 2014. [DOI: 10.1039/c4ra10196k] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We propose to create the cathode potential by introducing a redox couple to the cathode while using hydrogen peroxide to chemically charge the redox ions, which eliminates the mixed potential associated with direct reduction of hydrogen peroxide.
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Affiliation(s)
- L. An
- Department of Mechanical and Aerospace Engineering
- The Hong Kong University of Science and Technology
- Hong Kong SAR, China
| | - T. S. Zhao
- Department of Mechanical and Aerospace Engineering
- The Hong Kong University of Science and Technology
- Hong Kong SAR, China
| | - X. L. Zhou
- Department of Mechanical and Aerospace Engineering
- The Hong Kong University of Science and Technology
- Hong Kong SAR, China
| | - L. Wei
- Department of Mechanical and Aerospace Engineering
- The Hong Kong University of Science and Technology
- Hong Kong SAR, China
| | - X. H. Yan
- Department of Mechanical and Aerospace Engineering
- The Hong Kong University of Science and Technology
- Hong Kong SAR, China
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12
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Han SB, Lee YW, Kim SJ, Kim DY, Moon JS, Park AR, Park KW. Reduction of NO with Fe(ii) and subsequent regeneration of Fe(ii) in a fuel cell. RSC Adv 2012. [DOI: 10.1039/c2ra21750c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Han SB, Song YJ, Lee YW, Ko AR, Oh JK, Park KW. High-performance hydrogen fuel cell using nitrate reduction reaction on a non-precious catalyst. Chem Commun (Camb) 2011; 47:3496-8. [DOI: 10.1039/c0cc05534d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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The effect of ferric ions on the conductivity of various types of polymer cation exchange membranes. J Solid State Electrochem 2007. [DOI: 10.1007/s10008-007-0306-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Long JW, Dunn B, Rolison DR, White HS. Three-dimensional battery architectures. Chem Rev 2005; 104:4463-92. [PMID: 15669159 DOI: 10.1021/cr020740l] [Citation(s) in RCA: 455] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jeffrey W Long
- Surface Chemistry Branch, Code 6170, Naval Research Laboratory, Washington, DC 20375, USA.
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Ferrigno R, Stroock AD, Clark TD, Mayer M, Whitesides GM. Membraneless vanadium redox fuel cell using laminar flow. J Am Chem Soc 2002; 124:12930-1. [PMID: 12405803 DOI: 10.1021/ja020812q] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This paper describes the design and characterization of a small, membraneless redox fuel cell. The smallest channel dimensions of the cell were 2 mm x 50 mum or x 200 mum; the cell was fabricated in poly(dimethylsiloxane) using soft lithography. This all-vanadium fuel cell took advantage of laminar flow to obviate the need for a membrane to separate the solutions of oxidizing and reducing components.
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Affiliation(s)
- Rosaria Ferrigno
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA
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Folkesson B. Chemically regenerative redox fuel cells II. Regeneration reaction studies. J APPL ELECTROCHEM 1990. [DOI: 10.1007/bf01019564] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Larsson R, Folkesson B. Chemically regenerative redox fuel cells. I Membrane studies. J APPL ELECTROCHEM 1990. [DOI: 10.1007/bf01094299] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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