1
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Wu H, Yu H, Chow YL, Webley PA, Zhang J. Toward Durable CO 2 Electroreduction with Cu-Based Catalysts via Understanding Their Deactivation Modes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2403217. [PMID: 38845132 DOI: 10.1002/adma.202403217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2024] [Revised: 05/23/2024] [Indexed: 06/18/2024]
Abstract
The technology of CO2 electrochemical reduction (CO2ER) provides a means to convert CO2, a waste greenhouse gas, into value-added chemicals. Copper is the most studied element that is capable of catalyzing CO2ER to obtain multicarbon products, such as ethylene, ethanol, acetate, etc., at an appreciable rate. Under the operating condition of CO2ER, the catalytic performance of Cu decays because of several factors that alters the surface properties of Cu. In this review, these factors that cause the degradation of Cu-based CO2ER catalysts are categorized into generalized deactivation modes, that are applicable to all electrocatalytic systems. The fundamental principles of each deactivation mode and the associated effects of each on Cu-based catalysts are discussed in detail. Structure- and composition-activity relationship developed from recent in situ/operando characterization studies are presented as evidence of related deactivation modes in operation. With the aim to address these deactivation modes, catalyst design and reaction environment engineering rationales are suggested. Finally, perspectives and remarks built upon the recent advances in CO2ER are provided in attempts to improve the durability of CO2ER catalysts.
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Affiliation(s)
- Hsiwen Wu
- School of Chemistry, Monash University, Clayton, VIC, 3800, Australia
| | - Haoming Yu
- School of Chemistry, Monash University, Clayton, VIC, 3800, Australia
- Chemistry and Chemical Engineering School, Nanchang University, Nanchang, 330031, China
| | - Yuen-Leong Chow
- School of Chemistry, Monash University, Clayton, VIC, 3800, Australia
- Department of Chemical and Biological Engineering, Monash University, Clayton, VIC, 3800, Australia
| | - Paul A Webley
- Department of Chemical and Biological Engineering, Monash University, Clayton, VIC, 3800, Australia
- ARC Research Hub for Carbon Utilisation and Recycling, Monash University, Clayton, VIC, 3800, Australia
| | - Jie Zhang
- School of Chemistry, Monash University, Clayton, VIC, 3800, Australia
- Department of Chemical and Biological Engineering, Monash University, Clayton, VIC, 3800, Australia
- ARC Research Hub for Carbon Utilisation and Recycling, Monash University, Clayton, VIC, 3800, Australia
- ARC Centre of Excellence for Green Electrochemical Transformation of Carbon Dioxide, Monash University, Clayton, VIC, 3800, Australia
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2
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Haaring R, Kang PW, Lee JW, Lee J, Lee H. Nonconductive Metal Oxide Gas Diffusion Layer for Mitigating Electrowetting during CO 2 Electrolysis. ACS APPLIED MATERIALS & INTERFACES 2024; 16:28731-28741. [PMID: 38781021 DOI: 10.1021/acsami.4c05467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
Gas diffusion electrodes (GDEs) are extensively used for high current density electrochemical CO2 electrolysis (ECO2R), enabled by significantly reducing mass transfer resistance of CO2 to the catalyst layer. Conventionally, these GDEs are based upon hydrophobic carbon-based gas-diffusion layers (GDLs) that facilitate the gas transport; however, these supports are prone to flood with electrolyte during electrolysis. This potential-induced flooding, known as electrowetting, is related to the inherent conductivity of carbon and limits the activity of ECO2R. To investigate the effect of electrical conductivity more carefully, a GDE is constructed based on a Cu mesh with a nonconductive microporous GDL applied to this substrate, the latter composed of a mixture of metal oxide and polytetrafluoroethylene. With alumina as the metal oxide, a stable operation is obtained at -200 mA cm-2 with 70% selectivity for ECO2R (with over half toward C2+ products) without flooding as observed by in situ microscopy. On the contrary, with a Vulcan carbon-based GDL, the initial activity is rapidly lost as severe flooding ensues. It is reasoned that electrowetting is averted by virtue of the nonconductive nature of alumina, providing a new perspective on alternative GDL compositions and their influence on ECO2R performance.
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Affiliation(s)
- Robert Haaring
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Phil Woong Kang
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Jae Won Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Junpyo Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Hyunjoo Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
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3
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Park EJ, Jannasch P, Miyatake K, Bae C, Noonan K, Fujimoto C, Holdcroft S, Varcoe JR, Henkensmeier D, Guiver MD, Kim YS. Aryl ether-free polymer electrolytes for electrochemical and energy devices. Chem Soc Rev 2024; 53:5704-5780. [PMID: 38666439 DOI: 10.1039/d3cs00186e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
Anion exchange polymers (AEPs) play a crucial role in green hydrogen production through anion exchange membrane water electrolysis. The chemical stability of AEPs is paramount for stable system operation in electrolysers and other electrochemical devices. Given the instability of aryl ether-containing AEPs under high pH conditions, recent research has focused on quaternized aryl ether-free variants. The primary goal of this review is to provide a greater depth of knowledge on the synthesis of aryl ether-free AEPs targeted for electrochemical devices. Synthetic pathways that yield polyaromatic AEPs include acid-catalysed polyhydroxyalkylation, metal-promoted coupling reactions, ionene synthesis via nucleophilic substitution, alkylation of polybenzimidazole, and Diels-Alder polymerization. Polyolefinic AEPs are prepared through addition polymerization, ring-opening metathesis, radiation grafting reactions, and anionic polymerization. Discussions cover structure-property-performance relationships of AEPs in fuel cells, redox flow batteries, and water and CO2 electrolysers, along with the current status of scale-up synthesis and commercialization.
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Affiliation(s)
- Eun Joo Park
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | | | - Kenji Miyatake
- University of Yamanashi, Kofu 400-8510, Japan
- Waseda University, Tokyo 169-8555, Japan
| | - Chulsung Bae
- Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Kevin Noonan
- Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Cy Fujimoto
- Sandia National Laboratories, Albuquerque, NM 87123, USA
| | | | | | - Dirk Henkensmeier
- Korea Institute of Science and Technology (KIST), Seoul 02792, South Korea
- KIST School, University of Science and Technology (UST), Seoul 02792, South Korea
- KU-KIST School, Korea University, Seoul 02841, South Korea
| | - Michael D Guiver
- State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China.
| | - Yu Seung Kim
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
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4
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Ma M, Seger B. Rational Design of Local Reaction Environment for Electrocatalytic Conversion of CO 2 into Multicarbon Products. Angew Chem Int Ed Engl 2024; 63:e202401185. [PMID: 38576259 DOI: 10.1002/anie.202401185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 04/06/2024]
Abstract
The electrocatalytic conversion of CO2 into multi-carbon (C2+) products provides an attractive route for storing intermittent renewable electricity as fuels and feedstocks with high energy densities. Although substantial progress has been made in selective electrosynthesis of C2+ products via engineering the catalyst, rational design of the local reaction environment in the vicinity of catalyst surface also acts as an effective approach for further enhancing the performance. Here, we discuss recent advances and pertinent challenges in the modulation of local reaction environment, encompassing local pH, the choice of the species and concentrations of cations and anions as well as local reactant/intermediate concentrations, for achieving high C2+ selectivity. In addition, mechanistic understanding in the effects of the local reaction environment is also discussed. Particularly, the important progress extracted from in situ and operando spectroscopy techniques provides insights into how local reaction environment affects C-C coupling and key intermediates formation that lead to reaction pathways toward a desired C2+ product. The possible future direction in understanding and engineering the local reaction environment is also provided.
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Affiliation(s)
- Ming Ma
- School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an, 710049, People's Republic of China
| | - Brian Seger
- Surface Physics and Catalysis (Surfcat) Section, Department of Physics, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark
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5
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Heßelmann M, Lee JK, Chae S, Tricker A, Keller RG, Wessling M, Su J, Kushner D, Weber AZ, Peng X. Pure-Water-Fed Forward-Bias Bipolar Membrane CO 2 Electrolyzer. ACS APPLIED MATERIALS & INTERFACES 2024; 16:24649-24659. [PMID: 38711294 PMCID: PMC11103649 DOI: 10.1021/acsami.4c02799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 04/16/2024] [Accepted: 04/29/2024] [Indexed: 05/08/2024]
Abstract
Coupling renewable electricity to reduce carbon dioxide (CO2) electrochemically into carbon feedstocks offers a promising pathway to produce chemical fuels sustainably. While there has been success in developing materials and theory for CO2 reduction, the widespread deployment of CO2 electrolyzers has been hindered by challenges in the reactor design and operational stability due to CO2 crossover and (bi)carbonate salt precipitation. Herein, we design asymmetrical bipolar membranes assembled into a zero-gap CO2 electrolyzer fed with pure water, solving both challenges. By investigating and optimizing the anion-exchange-layer thickness, cathode differential pressure, and cell temperature, the forward-bias bipolar membrane CO2 electrolyzer achieves a CO faradic efficiency over 80% with a partial current density over 200 mA cm-2 at less than 3.0 V with negligible CO2 crossover. In addition, this electrolyzer achieves 0.61 and 2.1 mV h-1 decay rates at 150 and 300 mA cm-2 for 200 and 100 h, respectively. Postmortem analysis indicates that the deterioration of catalyst/polymer-electrolyte interfaces resulted from catalyst structural change, and ionomer degradation at reductive potential shows the decay mechanism. All these results point to the future research direction and show a promising pathway to deploy CO2 electrolyzers at scale for industrial applications.
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Affiliation(s)
- Matthias Heßelmann
- Energy
Technologies Area, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Chemical
Process Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
| | - Jason Keonhag Lee
- Energy
Technologies Area, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Sudong Chae
- Energy
Technologies Area, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Andrew Tricker
- Energy
Technologies Area, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Robert Gregor Keller
- Chemical
Process Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
| | - Matthias Wessling
- Chemical
Process Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
- DWI
Leibniz-Institute for Interactive Materials, Forckenbeckstr. 50, 52074 Aachen, Germany
| | - Ji Su
- Energy
Technologies Area, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Douglas Kushner
- Energy
Technologies Area, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Adam Z. Weber
- Energy
Technologies Area, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Xiong Peng
- Energy
Technologies Area, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
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6
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Penot C, Maniam KK, Paul S. Electrochemical Characterization of Electrodeposited Copper in Amine CO 2 Capture Media. MATERIALS (BASEL, SWITZERLAND) 2024; 17:1825. [PMID: 38673182 PMCID: PMC11051279 DOI: 10.3390/ma17081825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/05/2024] [Accepted: 04/08/2024] [Indexed: 04/28/2024]
Abstract
This study explores the stability of electrodeposited copper catalysts utilized in electrochemical CO2 reduction (ECR) across various amine media. The focus is on understanding the influence of different amine types, corrosion ramifications, and the efficacy of pulse ECR methodologies. Employing a suite of electrochemical techniques including potentiodynamic polarization, linear resistance polarization, cyclic voltammetry, and chronopotentiometry, the investigation reveals useful insights. The findings show that among the tested amines, CO2-rich monoethanolamine (MEA) exhibits the highest corrosion rate. However, in most cases, the rates remain within tolerable limits for ECR operations. Primary amines, notably monoethanolamine (MEA), show enhanced compatibility with ECR processes, attributable to their resistance against carbonate salt precipitation and sustained stability over extended durations. Conversely, tertiary amines such as methyldiethanolamine (MDEA) present challenges due to the formation of carbonate salts during ECR, impeding their effective utilization. This study highlights the effectiveness of pulse ECR strategies in stabilizing ECR. A noticeable shift in cathodic potential and reduced deposit formation on the catalyst surface through periodic oxidation underscores the efficacy of such strategies. These findings offer insights for optimizing ECR in amine media, thereby providing promising pathways for advancements in CO2 emission reduction technologies.
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Affiliation(s)
- Corentin Penot
- Materials Innovation Centre, School of Engineering, University of Leicester, Leicester LE1 7RH, UK; (C.P.); (K.K.M.)
| | - Kranthi Kumar Maniam
- Materials Innovation Centre, School of Engineering, University of Leicester, Leicester LE1 7RH, UK; (C.P.); (K.K.M.)
| | - Shiladitya Paul
- Materials Innovation Centre, School of Engineering, University of Leicester, Leicester LE1 7RH, UK; (C.P.); (K.K.M.)
- Materials Performance and Integrity Technology Group, TWI, Cambridge CB21 6AL, UK
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7
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Li G, Huang L, Wei C, Shen H, Liu Y, Zhang Q, Su J, Song Y, Guo W, Cao X, Tang BZ, Robert M, Ye R. Backbone Engineering of Polymeric Catalysts for High-Performance CO 2 Reduction in Bipolar Membrane Zero-Gap Electrolyzer. Angew Chem Int Ed Engl 2024; 63:e202400414. [PMID: 38348904 DOI: 10.1002/anie.202400414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Indexed: 02/29/2024]
Abstract
Bipolar membranes (BPMs) have emerged as a promising solution for mitigating CO2 losses, salt precipitation and high maintenance costs associated with the commonly used anion-exchange membrane electrode assembly for CO2 reduction reaction (CO2RR). However, the industrial implementation of BPM-based zero-gap electrolyzer is hampered by the poor CO2RR performance, largely attributed to the local acidic environment. Here, we report a backbone engineering strategy to improve the CO2RR performance of molecular catalysts in BPM-based zero-gap electrolyzers by covalently grafting cobalt tetraaminophthalocyanine onto a positively charged polyfluorene backbone (PF-CoTAPc). PF-CoTAPc shows a high acid tolerance in BPM electrode assembly (BPMEA), achieving a high FE of 82.6 % for CO at 100 mA/cm2 and a high CO2 utilization efficiency of 87.8 %. Notably, the CO2RR selectivity, carbon utilization efficiency and long-term stability of PF-CoTAPc in BPMEA outperform reported BPM systems. We attribute the enhancement to the stable cationic shield in the double layer and suppression of proton migration, ultimately inhibiting the undesired hydrogen evolution and improving the CO2RR selectivity. Techno-economic analysis shows the least energy consumption (957 kJ/mol) for the PF-CoTAPc catalyst in BPMEA. Our findings provide a viable strategy for designing efficient CO2RR catalysts in acidic environments.
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Affiliation(s)
- Geng Li
- Department of Chemistry, State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, 999077, P. R. China
| | - Libei Huang
- Division of Science, Engineering and Health Study, School of Professional Education and Executive Development, The Hong Kong Polytechnic University (PolyU SPEED), Hong Kong, P. R. China
| | - Chengpeng Wei
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Hanchen Shen
- Department of Chemistry and the Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Hong Kong, 999077, P. R. China
| | - Yong Liu
- Department of Chemistry, State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, 999077, P. R. China
| | - Qiang Zhang
- Department of Chemistry, State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, 999077, P. R. China
| | - Jianjun Su
- Department of Chemistry, State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, 999077, P. R. China
| | - Yun Song
- Department of Chemistry, State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, 999077, P. R. China
| | - Weihua Guo
- Department of Chemistry, State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, 999077, P. R. China
| | - Xiaohu Cao
- Department of Chemistry, State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, 999077, P. R. China
| | - Ben Zhong Tang
- Department of Chemistry and the Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Hong Kong, 999077, P. R. China
- School of Science and Engineering, Shenzhen Institute of Aggregate Science and Technology, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, P. R. China
| | - Marc Robert
- Université Paris Cité, Laboratoire d'Electrochimie Moléculaire, CNRS, 75006, Paris, France
| | - Ruquan Ye
- Department of Chemistry, State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, 999077, P. R. China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, Guangdong, 518057, P. R. China
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8
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Liu B, Guo W, Anderson SR, Johnstone SG, Wu S, Herrington MC, Gebbie MA. Exploring how cation entropy influences electric double layer formation and electrochemical reactivity. SOFT MATTER 2024; 20:351-364. [PMID: 38093637 DOI: 10.1039/d3sm01302b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Electric double layers are crucial to energy storage and electrocatalytic device performance. While double layer formation originates in electrostatic interactions, electric double layer properties are governed by a balance of both electrostatic and entropic driving forces. Favorable ion-surface electrostatic interactions attract counterions to charged surfaces to compensate, or "screen," potentials, but the confinement of these same ions from a bulk reservoir to the interface incurs an entropic penalty. Here, we use a dicationic imidazolium ionic liquid and its monovalent analogue to explore how cation valence and entropy influence double layer formation and electrochemical reactivity using CO2 electroreduction as a model reaction. We find that divalent and monovalent cations display similar CO2 reduction kinetics but differ vastly in steady-state reactivity due to rapid electrochemically induced precipitation of insulating dicationic (bi)carbonate films. Using in situ surface-enhanced Raman scattering spectroscopy, we find that potential-dependent cation reorientation occurs at similar potentials between the two ionic liquids, but the introduction of a covalent link in the divalent cation imparts a more ordered double layer structure that favors (bi)carbonate precipitation. In mixed monovalent-divalent electrolytes, we find that the divalent cations dominate interfacial properties by preferentially accumulating at surfaces even at very low relative concentrations. Our findings confirm that ion entropy plays a key role in modulating local electrochemical environments. Furthermore, we highlight how double layer properties are sensitive to the properties of counterions that pay the lowest entropic penalty to accumulate at interfaces. Overall, we illustrate that ion entropy provides a new knob to tune reaction microenvironments and unveil how entropy plays a major role in modulating electrochemical reactivity in mixed ion electrolytes.
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Affiliation(s)
- Beichen Liu
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
| | - Wenxiao Guo
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
| | - Seth R Anderson
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
| | - Samuel G Johnstone
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
| | - Siqi Wu
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
| | - Megan C Herrington
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
| | - Matthew A Gebbie
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
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9
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Pimlott DJD, Jewlal A, Kim Y, Berlinguette CP. Oxygen-Resistant CO 2 Reduction Enabled by Electrolysis of Liquid Feedstocks. J Am Chem Soc 2023; 145:25933-25937. [PMID: 37983190 DOI: 10.1021/jacs.3c08930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Electrolytic CO2 reduction fails in the presence of O2. This failure occurs because the reduction of O2 is thermodynamically favored over the reduction of CO2. Consequently, O2 must be removed from the CO2 feed prior to entering an electrolyzer, which is expensive. Here, we show that the use of liquid bicarbonate feedstocks (e.g., aqueous 3.0 M KHCO3), rather than gaseous CO2 feedstocks, enables efficient and selective CO2 reduction without additional procedures for removing O2. This effect is made possible because liquid bicarbonate solutions, which serve as a liquid CO2 carrier, deliver high concentrations of captured CO2 to the cathode, while the low solubility of O2 in aqueous media maintains a low O2 concentration at the same cathode surface. Consequently, electrolyzers fed with liquid bicarbonate feedstocks create an environment at the cathode that favors the reduction of CO2 over O2. We validate this claim by electrochemically converting CO2 into CO with reaction selectivities of 65% at 100 mA cm-2 using a 3.0 M KHCO3 solution bubbled with 100% CO2 or 100% O2. Similar experiments performed with a gaseous CO2 feedstock showed that merely 0.5% of O2 in the feedstock reduced CO selectivity by >90% after 1 h of electrolysis. Our findings demonstrate that a liquid bicarbonate feedstock enables efficient CO2 reduction without the need for expensive O2 removal steps.
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Affiliation(s)
- Douglas J D Pimlott
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Andrew Jewlal
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Yongwook Kim
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Curtis P Berlinguette
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
- Department of Chemical and Biological Engineering, The University of British Columbia, 2360 East Mall, Vancouver, British Columbia V6T 1Z3, Canada
- Stewart Blusson Quantum Matter Institute, The University of British Columbia, 2355 East Mall, Vancouver, British Columbia V6T 1Z4, Canada
- Canadian Institute for Advanced Research (CIFAR), 661 University Avenue, Toronto, Ontario M5G 1M1, Canada
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10
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Wang Z, Zhou Y, Qiu P, Xia C, Fang W, Jin J, Huang L, Deng P, Su Y, Crespo-Otero R, Tian X, You B, Guo W, Di Tommaso D, Pang Y, Ding S, Xia BY. Advanced Catalyst Design and Reactor Configuration Upgrade in Electrochemical Carbon Dioxide Conversion. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2303052. [PMID: 37589167 DOI: 10.1002/adma.202303052] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 07/28/2023] [Indexed: 08/18/2023]
Abstract
Electrochemical carbon dioxide reduction reaction (CO2 RR) driven by renewable energy shows great promise in mitigating and potentially reversing the devastating effects of anthropogenic climate change and environmental degradation. The simultaneous synthesis of energy-dense chemicals can meet global energy demand while decoupling emissions from economic growth. However, the development of CO2 RR technology faces challenges in catalyst discovery and device optimization that hinder their industrial implementation. In this contribution, a comprehensive overview of the current state of CO2 RR research is provided, starting with the background and motivation for this technology, followed by the fundamentals and evaluated metrics. Then the underlying design principles of electrocatalysts are discussed, emphasizing their structure-performance correlations and advanced electrochemical assembly cells that can increase CO2 RR selectivity and throughput. Finally, the review looks to the future and identifies opportunities for innovation in mechanism discovery, material screening strategies, and device assemblies to move toward a carbon-neutral society.
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Affiliation(s)
- Zhitong Wang
- Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), Hubei Key Laboratory of Material Chemistry and Service Failure, State Key Laboratory of Materials Processing and Die & Mould Technology, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Rd, Wuhan, 430074, China
- School of Marine Science and Engineering, Hainan Provincial Key Lab of Fine Chemistry, School of Chemistry and Chemical Engineering, Hainan University, Haikou, 570228, China
| | - Yansong Zhou
- Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), Hubei Key Laboratory of Material Chemistry and Service Failure, State Key Laboratory of Materials Processing and Die & Mould Technology, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Rd, Wuhan, 430074, China
| | - Peng Qiu
- School of Optical and Electronic Information, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology (HUST), 1037 Luoyu Road, Wuhan, 430074, China
| | - Chenfeng Xia
- Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), Hubei Key Laboratory of Material Chemistry and Service Failure, State Key Laboratory of Materials Processing and Die & Mould Technology, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Rd, Wuhan, 430074, China
| | - Wensheng Fang
- Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), Hubei Key Laboratory of Material Chemistry and Service Failure, State Key Laboratory of Materials Processing and Die & Mould Technology, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Rd, Wuhan, 430074, China
| | - Jian Jin
- School of Optical and Electronic Information, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology (HUST), 1037 Luoyu Road, Wuhan, 430074, China
| | - Lei Huang
- Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), Hubei Key Laboratory of Material Chemistry and Service Failure, State Key Laboratory of Materials Processing and Die & Mould Technology, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Rd, Wuhan, 430074, China
| | - Peilin Deng
- School of Marine Science and Engineering, Hainan Provincial Key Lab of Fine Chemistry, School of Chemistry and Chemical Engineering, Hainan University, Haikou, 570228, China
| | - Yaqiong Su
- School of Chemistry, Xi'an Jiaotong University, 28 Xianning West Rd, Xi'an, 710049, China
| | - Rachel Crespo-Otero
- Department of Chemistry, University of College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Xinlong Tian
- School of Marine Science and Engineering, Hainan Provincial Key Lab of Fine Chemistry, School of Chemistry and Chemical Engineering, Hainan University, Haikou, 570228, China
| | - Bo You
- Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), Hubei Key Laboratory of Material Chemistry and Service Failure, State Key Laboratory of Materials Processing and Die & Mould Technology, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Rd, Wuhan, 430074, China
| | - Wei Guo
- Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), Hubei Key Laboratory of Material Chemistry and Service Failure, State Key Laboratory of Materials Processing and Die & Mould Technology, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Rd, Wuhan, 430074, China
| | - Devis Di Tommaso
- School of Physical and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Yuanjie Pang
- School of Optical and Electronic Information, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology (HUST), 1037 Luoyu Road, Wuhan, 430074, China
| | - Shujiang Ding
- School of Chemistry, Xi'an Jiaotong University, 28 Xianning West Rd, Xi'an, 710049, China
| | - Bao Yu Xia
- Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), Hubei Key Laboratory of Material Chemistry and Service Failure, State Key Laboratory of Materials Processing and Die & Mould Technology, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Rd, Wuhan, 430074, China
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11
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Xu M, Deng T, Liu LX, Han X. Enrichment Strategies for Efficient CO 2 Electroreduction in Acidic Electrolytes. Chemistry 2023; 29:e202302382. [PMID: 37707507 DOI: 10.1002/chem.202302382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 09/11/2023] [Accepted: 09/14/2023] [Indexed: 09/15/2023]
Abstract
Electrochemical CO2 reduction reaction (CO2 RR) has been recognized as an appealing route to remarkably accelerate the carbon-neutral cycle and reduce carbon emissions. Notwithstanding great catalytic activity that has been acquired in neutral and alkaline conditions, the carbonates generated from the inevitable reaction of the input CO2 with the hydroxide severely lower carbon utilization and energy efficiency. By contrast, CO2 RR in an acidic condition can effectively circumvent the carbonate issues; however, the activity and selectivity of CO2 RR in acidic electrolytes will be decreased significantly due to the competing hydrogen evolution reaction (HER). Enriching the CO2 and the key intermediates around the catalyst surface can promote the reaction rate and enhance the product selectivity, providing a promising way to boost the performance of CO2 RR. In this review, the catalytic mechanism and key technique challenges of CO2 RR are first introduced. Then, the critical progress of enrichment strategies for promoting the CO2 RR in the acidic electrolyte is summarized with three aspects: catalyst design, electrolyte regulation, and electrolyzer optimization. Finally, some insights and perspectives for further development of enrichment strategies in acidic CO2 RR are expounded.
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Affiliation(s)
- Meng Xu
- Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou, 221116, P. R. China
| | - Taojiang Deng
- Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou, 221116, P. R. China
| | - Li-Xia Liu
- Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou, 221116, P. R. China
| | - Xiguang Han
- Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou, 221116, P. R. China
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12
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Lai W, Qiao Y, Wang Y, Huang H. Stability Issues in Electrochemical CO 2 Reduction: Recent Advances in Fundamental Understanding and Design Strategies. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2306288. [PMID: 37562821 DOI: 10.1002/adma.202306288] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 08/08/2023] [Indexed: 08/12/2023]
Abstract
Electrochemical CO2 reduction reaction (CO2 RR) offers a promising approach to close the anthropogenic carbon cycle and store intermittent renewable energy in fuels or chemicals. On the path to commercializing this technology, achieving the long-term operation stability is a central requirement but still confronts challenges. This motivates to organize the present review to systematically discuss the stability issue of CO2 RR. This review starts from the fundamental understanding on the destabilization mechanisms of CO2 RR, with focus on the degradation of electrocatalyst and change of reaction microenvironment during continuous electrolysis. Subsequently, recent efforts on catalyst design to stabilize the active sites are summarized, where increasing atomic binding strength to resist surface reconstruction is highlighted. Next, the optimization of electrolysis system to enhance the operation stability by maintaining reaction microenvironment especially mitigating flooding and carbonate problems is demonstrated. The manipulation on operation conditions also enables to prolong CO2 RR lifespan through recovering catalytically active sites and mass transport process. This review finally ends up by indicating the challenges and future opportunities.
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Affiliation(s)
- Wenchuan Lai
- College of Materials Science and Engineering, Hunan University, Changsha, Hunan, 410082, P. R. China
- College of Chemistry and Materials Science, Nanjing Normal University, Nanjing, Jiangsu, 210023, P. R. China
| | - Yan Qiao
- College of Materials Science and Engineering, Hunan University, Changsha, Hunan, 410082, P. R. China
| | - Yanan Wang
- College of Materials Science and Engineering, Hunan University, Changsha, Hunan, 410082, P. R. China
| | - Hongwen Huang
- College of Materials Science and Engineering, Hunan University, Changsha, Hunan, 410082, P. R. China
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13
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Jiang Z, Zhang M, Chen X, Wang B, Fan W, Yang C, Yang X, Zhang Z, Yang X, Li C, Zhou T. A Bismuth-Based Zeolitic Organic Framework with Coordination-Linked Metal Cages for Efficient Electrocatalytic CO 2 Reduction to HCOOH. Angew Chem Int Ed Engl 2023; 62:e202311223. [PMID: 37721360 DOI: 10.1002/anie.202311223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 09/17/2023] [Accepted: 09/18/2023] [Indexed: 09/19/2023]
Abstract
Zeolitic metal-organic frameworks (ZMOFs) have emerged as one of the most promsing catalysts for energy conversion, but they suffer from either weak bonding between metal-organic cubes (MOCs) that decrease their stability during catalysis processes or low activity due to inadequate active sites. In this work, through ligand-directing strategy, we successfully obtain an unprecedented bismuth-based ZMOF (Bi-ZMOF) featuring a ACO topological crystal structure with strong coordination bonding between the Bi-based cages. As a result, it enables efficient reduction of CO2 to formic acid (HCOOH) with Faradaic efficiency as high as 91 %. A combination of in situ surface-enhanced infrared absorption spectroscopy and density functional theory calculation reveals that the Bi-N coordination contributes to facilitating charge transfer from N to Bi atoms, which stabilize the intermediate to boost the reduction efficiency of CO2 to HCOOH. This finding highlights the importance of the coordination environment of metal active sites on electrocatalytic CO2 reduction. We believe that this work will offer a new clue to rationally design zeolitic MOFs for catalytic reaction.
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Affiliation(s)
- Zhiqiang Jiang
- Vanadium and Titanium Resource Comprehensive Utilization Key Laboratory of Sichuan Province, Panzhihua University, Panzhihua, 617000, P. R. China
| | - Minyi Zhang
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350002, P. R. China
| | - Xingliang Chen
- Vanadium and Titanium Resource Comprehensive Utilization Key Laboratory of Sichuan Province, Panzhihua University, Panzhihua, 617000, P. R. China
| | - Bing Wang
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350002, P. R. China
| | - Wenjuan Fan
- Vanadium and Titanium Resource Comprehensive Utilization Key Laboratory of Sichuan Province, Panzhihua University, Panzhihua, 617000, P. R. China
| | - Chenhuai Yang
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, P. R. China
| | - Xiaoju Yang
- School of Chemistry and Chemical Engineering, Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
| | - Zhicheng Zhang
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, P. R. China
| | - Xuan Yang
- School of Chemistry and Chemical Engineering, Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
| | - Chunsen Li
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350002, P. R. China
| | - Tianhua Zhou
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350002, P. R. China
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14
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Iglesias van Montfort HP, Li M, Irtem E, Abdinejad M, Wu Y, Pal SK, Sassenburg M, Ripepi D, Subramanian S, Biemolt J, Rufford TE, Burdyny T. Non-invasive current collectors for improved current-density distribution during CO 2 electrolysis on super-hydrophobic electrodes. Nat Commun 2023; 14:6579. [PMID: 37852966 PMCID: PMC10584973 DOI: 10.1038/s41467-023-42348-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 10/09/2023] [Indexed: 10/20/2023] Open
Abstract
Electrochemical reduction of CO2 presents an attractive way to store renewable energy in chemical bonds in a potentially carbon-neutral way. However, the available electrolyzers suffer from intrinsic problems, like flooding and salt accumulation, that must be overcome to industrialize the technology. To mitigate flooding and salt precipitation issues, researchers have used super-hydrophobic electrodes based on either expanded polytetrafluoroethylene (ePTFE) gas-diffusion layers (GDL's), or carbon-based GDL's with added PTFE. While the PTFE backbone is highly resistant to flooding, the non-conductive nature of PTFE means that without additional current collection the catalyst layer itself is responsible for electron-dispersion, which penalizes system efficiency and stability. In this work, we present operando results that illustrate that the current distribution and electrical potential distribution is far from a uniform distribution in thin catalyst layers (~50 nm) deposited onto ePTFE GDL's. We then compare the effects of thicker catalyst layers (~500 nm) and a newly developed non-invasive current collector (NICC). The NICC can maintain more uniform current distributions with 10-fold thinner catalyst layers while improving stability towards ethylene (≥ 30%) by approximately two-fold.
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Affiliation(s)
| | - Mengran Li
- Department of Chemical Engineering, Delft University of Technology; 9 van der Maasweg, Delft, 2629HZ, the Netherlands
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Erdem Irtem
- Department of Chemical Engineering, Delft University of Technology; 9 van der Maasweg, Delft, 2629HZ, the Netherlands
| | - Maryam Abdinejad
- Department of Chemical Engineering, Delft University of Technology; 9 van der Maasweg, Delft, 2629HZ, the Netherlands
| | - Yuming Wu
- School of Chemical Engineering, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Santosh K Pal
- Department of Chemical Engineering, Delft University of Technology; 9 van der Maasweg, Delft, 2629HZ, the Netherlands
| | - Mark Sassenburg
- Department of Chemical Engineering, Delft University of Technology; 9 van der Maasweg, Delft, 2629HZ, the Netherlands
| | - Davide Ripepi
- Department of Chemical Engineering, Delft University of Technology; 9 van der Maasweg, Delft, 2629HZ, the Netherlands
| | - Siddhartha Subramanian
- Department of Chemical Engineering, Delft University of Technology; 9 van der Maasweg, Delft, 2629HZ, the Netherlands
| | - Jasper Biemolt
- Department of Chemical Engineering, Delft University of Technology; 9 van der Maasweg, Delft, 2629HZ, the Netherlands
| | - Thomas E Rufford
- School of Chemical Engineering, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Thomas Burdyny
- Department of Chemical Engineering, Delft University of Technology; 9 van der Maasweg, Delft, 2629HZ, the Netherlands.
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15
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Haaring R, Kang PW, Guo Z, Lee JW, Lee H. Developing Catalysts Integrated in Gas-Diffusion Electrodes for CO 2 Electrolyzers. Acc Chem Res 2023; 56:2595-2605. [PMID: 37698057 DOI: 10.1021/acs.accounts.3c00349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
ConspectusAs the demand for a carbon-neutral society grows rapidly, research on CO2 electrolysis has become very active. Many catalysts are reported for converting CO2 into value-added products by electrochemical reactions, which have to perform at high Faradaic and energy efficiency to become commercially viable. Various types of CO2 electrolyzers have been used in this effort, such as the H-cell, flow cell, and zero-gap membrane-electrode assembly (MEA) cell. H-cell studies are conducted with electrodes immersed in CO2-saturated electrolyte and have been used to elucidate reaction pathways and kinetic parameters of electrochemical CO2 reduction on many types of catalytic surfaces. From a transport phenomenological perspective, the low solubility and diffusion of CO2 to the electrode surface severely limit the maximum attainable current density, and this metric has been shown to have significant influence on the product spectrum. Flow and MEA cells provide a solution in the form of gas-diffusion electrodes (GDEs) that enable gaseous CO2 to closely reach the catalyst layer and yield record-high current densities. Because GDEs involve a complicated interface consisting of the catalyst surface, gaseous CO2, polymer overlayers, and liquid electrolyte, catalysts with high intrinsic activity might not show high performance in these GDE-based electrolyzers. Catalysts showing low overpotentials at low current densities may suffer from poor electron conductivity and mass transfer limitations at high current densities. Furthermore, the stability of the GDE-based catalysts is often compromised as CO2 electrolysis is pursued with high activity, most notoriously by electrolyte flooding.In this Account, we introduce recent examples where the electrocatalysts were integrated in GDEs, achieving high production rates. The performance of such systems is contingent on both GDE and cell design, and various parameters that affect the cell performance are discussed. Gaseous products, such as carbon monoxide, methane, and ethylene, and liquid products, such as formate and ethanol, have been mainly reported with high partial current density using the flow or MEA cells. Different strategies to this end are described, such as controlling microenvironments by the use of polymers mixed within the catalyst layer or the functionalization of catalyst surfaces with ligands to increase local concentrations of intermediates. Unique CO2 electrolyzer designs are also treated, including the incorporation of light-responsive plasmonic catalysts in the GDE, and combining the electrolyzer with a fermenter utilizing a microbial biocatalyst to synthesize complex multicarbon products. Basic conditions which the catalyst should satisfy to be adapted in the GDEs are listed, and our perspective is provided.
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Affiliation(s)
- Robert Haaring
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Phil Woong Kang
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Zunmin Guo
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Jae Won Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Hyunjoo Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
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16
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El-Nagar GA, Haun F, Gupta S, Stojkovikj S, Mayer MT. Unintended cation crossover influences CO 2 reduction selectivity in Cu-based zero-gap electrolysers. Nat Commun 2023; 14:2062. [PMID: 37045816 PMCID: PMC10097803 DOI: 10.1038/s41467-023-37520-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Accepted: 03/21/2023] [Indexed: 04/14/2023] Open
Abstract
Membrane electrode assemblies enable CO2 electrolysis at industrially relevant rates, yet their operational stability is often limited by formation of solid precipitates in the cathode pores, triggered by cation crossover from the anolyte due to imperfect ion exclusion by anion exchange membranes. Here we show that anolyte concentration affects the degree of cation movement through the membranes, and this substantially influences the behaviors of copper catalysts in catholyte-free CO2 electrolysers. Systematic variation of the anolyte (KOH or KHCO3) ionic strength produced a distinct switch in selectivity between either predominantly CO or C2+ products (mainly C2H4) which closely correlated with the quantity of alkali metal cation (K+) crossover, suggesting cations play a key role in C-C coupling reaction pathways even in cells without discrete liquid catholytes. Operando X-ray absorption and quasi in situ X-ray photoelectron spectroscopy revealed that the Cu surface speciation showed a strong dependence on the anolyte concentration, wherein dilute anolytes resulted in a mixture of Cu+ and Cu0 surface species, while concentrated anolytes led to exclusively Cu0 under similar testing conditions. These results show that even in catholyte-free cells, cation effects (including unintentional ones) significantly influence reaction pathways, important to consider in future development of catalysts and devices.
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Affiliation(s)
- Gumaa A El-Nagar
- Electrochemical Conversion, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109, Berlin, Germany.
| | - Flora Haun
- Electrochemical Conversion, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109, Berlin, Germany
- Institut für Chemie & Biochemie, Freie Universität Berlin, 14195, Berlin, Germany
| | - Siddharth Gupta
- Electrochemical Conversion, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109, Berlin, Germany
- Institut für Chemie & Biochemie, Freie Universität Berlin, 14195, Berlin, Germany
| | - Sasho Stojkovikj
- Electrochemical Conversion, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109, Berlin, Germany
- Institut für Chemie & Biochemie, Freie Universität Berlin, 14195, Berlin, Germany
| | - Matthew T Mayer
- Electrochemical Conversion, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109, Berlin, Germany.
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