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Wu YT, Kumbhar SV, Tsai RF, Yang YC, Zeng WQ, Wang YH, Hsu WC, Chiang YW, Yang T, Lu IC, Wang YH. Manipulating the Rate and Overpotential for Electrochemical Water Oxidation: Mechanistic Insights for Cobalt Catalysts Bearing Noninnocent Bis(benzimidazole)pyrazolide Ligands. ACS ORGANIC & INORGANIC AU 2024; 4:306-318. [PMID: 38855334 PMCID: PMC11157513 DOI: 10.1021/acsorginorgau.3c00061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 01/22/2024] [Accepted: 01/23/2024] [Indexed: 06/11/2024]
Abstract
Electrochemical water oxidation is known as the anodic reaction of water splitting. Efficient design and earth-abundant electrocatalysts are crucial to this process. Herein, we report a family of catalysts (1-3) bearing bis(benzimidazole)pyrazolide ligands (H 2 L1-H 2 L3). H 2 L3 contains electron-donating substituents and noninnocent components, resulting in catalyst 3 exhibiting unique performance. Kinetic studies show first-order kinetic dependence on [3] and [H2O] under neutral and alkaline conditions. In contrast to previously reported catalyst 1, catalyst 3 exhibits an insignificant kinetic isotope effect of 1.25 and zero-order dependence on [NaOH]. Based on various spectroscopic methods and computational findings, the L3Co2 III(μ-OH) species is proposed to be the catalyst resting state and the nucleophilic attack of water on this species is identified as the turnover-limiting step of the catalytic reaction. Computational studies provided insights into how the interplay between the electronic effect and ligand noninnocence results in catalyst 3 acting via a different reaction mechanism. The variation in the turnover-limiting step and catalytic potentials of species 1-3 leads to their catalytic rates being independent of the overpotential, as evidenced by Eyring analysis. Overall, we demonstrate how ligand design may be utilized to retain good water oxidation activity at low overpotentials.
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Affiliation(s)
- Yu-Ting Wu
- Department
of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Sharad V. Kumbhar
- Department
of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Ruei-Feng Tsai
- Department
of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Yung-Ching Yang
- Department
of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan
| | - Wan-Qin Zeng
- Department
of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan
| | - Yu-Han Wang
- Department
of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Wan-Chi Hsu
- Department
of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Yun-Wei Chiang
- Department
of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Tzuhsiung Yang
- Department
of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - I-Chung Lu
- Department
of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan
| | - Yu-Heng Wang
- Department
of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
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2
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Li YY, Liao RZ. Exploring the Cooperation of the Redox Non-Innocent Ligand and Di-Cobalt Center for the Water Oxidation Reaction Catalyzed by a Binuclear Complex. CHEMSUSCHEM 2024:e202400123. [PMID: 38664234 DOI: 10.1002/cssc.202400123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 04/24/2024] [Indexed: 05/25/2024]
Abstract
Water oxidation is a crucial reaction in the artificial photosynthesis system. In the present work, density functional calculations were employed to decipher the mechanism of water oxidation catalyzed by a binuclear cobalt complex, which was disclosed to be a homogeneous water oxidation catalyst in pH=7 phosphate buffer. The calculations showed that the catalytic cycle starts from the CoIII,III-OH2 species. Then, a proton-coupled electron transfer followed by a one-electron transfer process leads to the generation of the formal CoIV,IV-OH intermediate. The subsequent PCET produces the active species, namely the formal CoIV,V=O intermediate (4). The oxidation processes mainly occur on the ligand moiety, including the coordinated water moiety, implying a redox non-innocent behavior. Two cobalt centers keep their oxidation states and provide one catalytic center for water activation during the oxidation process. 4 triggers the O-O bond formation via the water nucleophilic attack pathway, in which the phosphate buffer ion functions as the proton acceptor. The O-O bond formation is the rate-limiting step with a calculated total barrier of 17.7 kcal/mol. The last electron oxidation process coupled with an intramolecular electron transfer results in the generation of O2.
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Affiliation(s)
- Ying-Ying Li
- School of Chemistry and Chemical Engineering, Zhengzhou Normal University, Zhengzhou, 450044, P. R. China
| | - Rong-Zhen Liao
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Hubei Key Laboratory of Materials Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
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3
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Anferov SW, Boyn JN, Mazziotti DA, Anderson JS. Selective Cobalt-Mediated Formation of Hydrogen Peroxide from Water under Mild Conditions via Ligand Redox Non-Innocence. J Am Chem Soc 2024; 146:5855-5863. [PMID: 38375752 DOI: 10.1021/jacs.3c11032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Despite the broad importance of hydrogen peroxide (H2O2) in oxidative transformations, there are comparatively few viable routes for its production. The majority of commercial H2O2 is currently produced by the stepwise reduction of dioxygen (O2) via the anthraquinone process, but direct electrochemical formation from water (H2O) would have several advantages─namely, avoiding flammable gases or stepwise separations. However, the selective oxidation of H2O to form H2O2 over the thermodynamically favored product of O2 is a difficult synthetic challenge. Here, we present a molecular H2O oxidation system with excellent selectivity for H2O2 that functions both stoichiometrically and catalytically. We observe high efficiency for electrocatalytic H2O2 production at low overpotential with no O2 observed under any conditions. Mechanistic studies with both calculations and kinetic analyses from isolated intermediates suggest that H2O2 formation occurs in a bimolecular fashion via a dinuclear H2O2-bridged intermediate with an important role for a redox non-innocent ligand. This system showcases the ability of metal-ligand cooperativity and strategic design of the secondary coordination sphere to promote kinetically and thermodynamically challenging selectivity in oxidative catalysis.
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Affiliation(s)
- Sophie W Anferov
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60627, United States
| | - Jan-Niklas Boyn
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - David A Mazziotti
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60627, United States
| | - John S Anderson
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60627, United States
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4
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Lv H, Zhang XP, Guo K, Han J, Guo H, Lei H, Li X, Zhang W, Apfel UP, Cao R. Coordination Tuning of Metal Porphyrins for Improved Oxygen Evolution Reaction. Angew Chem Int Ed Engl 2023; 62:e202305938. [PMID: 37550259 DOI: 10.1002/anie.202305938] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 08/06/2023] [Accepted: 08/07/2023] [Indexed: 08/09/2023]
Abstract
The nucleophilic attack of water or hydroxide on metal-oxo units forms an O-O bond in the oxygen evolution reaction (OER). Coordination tuning to improve this attack is intriguing but has been rarely realized. We herein report on improved OER catalysis by metal porphyrin 1-M (M=Co, Fe) with a coordinatively unsaturated metal ion. We designed and synthesized 1-M by sterically blocking one porphyrin side with a tethered tetraazacyclododecane unit. With this protection, the metal-oxo species generated in OER can maintain an unoccupied trans axial site. Importantly, 1-M displays a higher OER activity in alkaline solutions than analogues lacking such an axial protection by decreasing up to 150-mV overpotential to achieve 10 mA/cm2 current density. Theoretical studies suggest that with an unoccupied trans axial site, the metal-oxo unit becomes more positively charged and thus is more favoured for the hydroxide nucleophilic attack as compared to metal-oxo units bearing trans axial ligands.
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Affiliation(s)
- Haoyuan Lv
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Xue-Peng Zhang
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Kai Guo
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Jinxiu Han
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Hongbo Guo
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Haitao Lei
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Xialiang Li
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Wei Zhang
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Ulf-Peter Apfel
- Ruhr-Universität Bochum, Fakultät für Chemie und Biochemie, Anorganische Chemie I, Universitätsstrasse 150, 44801, Bochum, Germany
- Fraunhofer UMSICHT, Osterfelder Strasse 3, 46047, Oberhausen, Germany
| | - Rui Cao
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
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Zhao Y, Adiyeri Saseendran DP, Huang C, Triana CA, Marks WR, Chen H, Zhao H, Patzke GR. Oxygen Evolution/Reduction Reaction Catalysts: From In Situ Monitoring and Reaction Mechanisms to Rational Design. Chem Rev 2023; 123:6257-6358. [PMID: 36944098 DOI: 10.1021/acs.chemrev.2c00515] [Citation(s) in RCA: 55] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
The oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are core steps of various energy conversion and storage systems. However, their sluggish reaction kinetics, i.e., the demanding multielectron transfer processes, still render OER/ORR catalysts less efficient for practical applications. Moreover, the complexity of the catalyst-electrolyte interface makes a comprehensive understanding of the intrinsic OER/ORR mechanisms challenging. Fortunately, recent advances of in situ/operando characterization techniques have facilitated the kinetic monitoring of catalysts under reaction conditions. Here we provide selected highlights of recent in situ/operando mechanistic studies of OER/ORR catalysts with the main emphasis placed on heterogeneous systems (primarily discussing first-row transition metals which operate under basic conditions), followed by a brief outlook on molecular catalysts. Key sections in this review are focused on determination of the true active species, identification of the active sites, and monitoring of the reactive intermediates. For in-depth insights into the above factors, a short overview of the metrics for accurate characterizations of OER/ORR catalysts is provided. A combination of the obtained time-resolved reaction information and reliable activity data will then guide the rational design of new catalysts. Strategies such as optimizing the restructuring process as well as overcoming the adsorption-energy scaling relations will be discussed. Finally, pending current challenges and prospects toward the understanding and development of efficient heterogeneous catalysts and selected homogeneous catalysts are presented.
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Affiliation(s)
- Yonggui Zhao
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | | | - Chong Huang
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Carlos A Triana
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Walker R Marks
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Hang Chen
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Han Zhao
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Greta R Patzke
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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6
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Exploring the Emergent Redox Chemistry of Pd(II) Nodes with Pendant Ferrocenes: From Precursors, through Building Blocks, to Self-Assemblies. INORGANICS 2023. [DOI: 10.3390/inorganics11030122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2023] Open
Abstract
Energy-relevant small molecule activations and related processes are often multi-electron in nature. Ferrocene is iconic for its well-behaved one-electron chemistry, and it is often used to impart redox activity to self-assembled architectures. When multiple ferrocenes are present as pendant groups in a single structure, they often behave as isolated sites with no separation of their redox events. Herein, we study a suite of molecules culminating in a self-assembled palladium(II) truncated tetrahedron (TT) with six pendant ferrocene moieties using the iron(III/II) couple to inform about the electronic structure and, in some cases, subsequent reactivity. Notably, although known ferrocene-containing metallacycles and cages show simple reversible redox chemistry, this TT undergoes a complex multi-step electrochemical mechanism upon oxidation. The electrochemical behavior was observed by voltammetric and spectroelectrochemical techniques and suggests that the initial Fc-centered oxidation is coupled to a subsequent change in species solubility and deposition of a film onto the working electrode, which is followed by a second separable electrochemical oxidation event. The complicated electrochemical behavior of this self-assembly reveals emergent properties resulting from organizing multiple ferrocene subunits into a discrete structure. We anticipate that such structures may provide the basis for multiple charge separation events to drive important processes related to energy capture, storage, and use, especially as the electronic communication between sites is further tuned.
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7
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Hsu WC, Zeng WQ, Lu IC, Yang T, Wang YH. Dinuclear Cobalt Complexes for Homogeneous Water Oxidation: Tuning Rate and Overpotential through the Non-Innocent Ligand. CHEMSUSCHEM 2022; 15:e202201317. [PMID: 36083105 DOI: 10.1002/cssc.202201317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 09/09/2022] [Indexed: 06/15/2023]
Abstract
In this study, dinuclear cobalt complexes (1 and 2) featuring bis(benzimidazole)pyrazolide-type ligands (H2 L and Me2 L) were prepared and evaluated as molecular electrocatalysts for water oxidation. Notably, 1 bearing a non-innocent ligand (H2 L) displayed faster catalytic turnover than 2 under alkaline conditions, and the base dependence of water oxidation and kinetic isotope effect analysis indicated that the reaction mediated by 1 proceeded by a different mechanism relative to 2. Spectroelectrochemical, cold-spray ionization mass spectrometric and computational studies found that double deprotonation of 1 under alkaline conditions cathodically shifted the catalysis-initiating potential and further altered the turnover-limiting step from nucleophilic water attack on (H2 L)CoIII 2 (superoxo) to deprotonation of (L)CoIII 2 (OH)2 . The rate-overpotential analysis and catalytic Tafel plots showed that 1 exhibited a significantly higher rate than previously reported Ru-based dinuclear electrocatalysts at similar overpotentials. These observations suggest that using non-innocent ligands is a valuable strategy for designing effective metal-based molecular water oxidation catalysts.
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Affiliation(s)
- Wan-Chi Hsu
- Department of Chemistry, National Tsing Hua University, 101, Sec 2, Kuang-Fu Rd., 30013, Hsinchu, Taiwan
| | - Wan-Qin Zeng
- Department of Chemistry, National Chung Hsing University, 145, Xingda Rd., South Dist., 402, Taichung, Taiwan
| | - I-Chung Lu
- Department of Chemistry, National Chung Hsing University, 145, Xingda Rd., South Dist., 402, Taichung, Taiwan
| | - Tzuhsiung Yang
- Department of Chemistry, National Tsing Hua University, 101, Sec 2, Kuang-Fu Rd., 30013, Hsinchu, Taiwan
| | - Yu-Heng Wang
- Department of Chemistry, National Tsing Hua University, 101, Sec 2, Kuang-Fu Rd., 30013, Hsinchu, Taiwan
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8
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Armstrong CG, Potter M, Malcomson T, Hogue RW, Armstrong SM, Kerridge A, Toghill K. Exploring the Electrochemistry of Iron Dithiolene and Its Potential for Electrochemical Homogeneous Carbon Dioxide Reduction. ChemElectroChem 2022; 9:e202200610. [PMID: 36246849 PMCID: PMC9546257 DOI: 10.1002/celc.202200610] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In this work, the dithiolene complex iron(III) bis‐maleonitriledithiolene [Fe(mnt)2] is characterised and evaluated as a homogeneous CO2 reduction catalyst. Electrochemically the Fe(mnt)2 is reduced twice to the trianionic Fe(mnt)23− state, which is correspondingly found to be active towards CO2. Interestingly, the first reduction event appears to comprise overlapping reversible couples, attributed to the presence of both a dimeric and monomeric form of the dithiolene complex. In acetonitrile Fe(mnt)2 demonstrates a catalytic response to CO2 yielding typical two‐electron reduction products: H2, CO and CHOOH. The product distribution and yield were governed by the proton source. Operating with H2O as the proton source gave only H2 and CO as products, whereas using 2,2,2‐trifluoroethanol gave 38 % CHOOH faradaic efficiency with H2 and CO as minor products.
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Affiliation(s)
| | - Mark Potter
- Lancaster University Faculty of Science and Technology Chemistry UNITED KINGDOM
| | - Thomas Malcomson
- Manchester University Chemistry School of Natural SciencesUniversity of Manchester M13 9PL Manchester UNITED KINGDOM
| | - Ross W. Hogue
- Leiden University: Universiteit Leiden Leiden Institute of Chemistry LIC/Energy & SustainabilityGorlaeus LaboratoriesEinsteinweg 55 2333 CC Leiden NETHERLANDS
| | | | | | - Kathryn Toghill
- Lancaster University Chemistry Faraday Buildings LA1 4YB Lancaster UNITED KINGDOM
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