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Liu Y, Zhang S, Ma S, Sun X, Wang Y, Liu F, Li Y, Ma Y, Xu X, Xue Y, Tang C, Zhang J. Electronic Structure Modification of MnO 2 Nanosheet Arrays with Enhanced Water Oxidation Activity and Stability by Nitrogen Plasma. ACS APPLIED MATERIALS & INTERFACES 2024; 16:36498-36508. [PMID: 38963822 DOI: 10.1021/acsami.4c07973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/06/2024]
Abstract
The strategic design of catalysts for the oxygen evolution reaction (OER) is crucial in tackling the substantial energy demands associated with hydrogen production in electrolytic water splitting. Despite extensive research on birnessite (δ-MnO2) manganese oxides to enhance catalytic activity by modulating Mn3+ species, the ongoing challenge is to simultaneously stabilize Mn3+ while improving overall activity. Herein, oxygen (O) vacancies and nitrogen (N) doping have been simultaneously introduced into the MnO2 through a simple nitrogen plasma approach, resulting in efficient OER performance. The optimized N-MnO2v electrocatalyst exhibits outstanding OER activity in alkaline electrolyte, reducing the overpotential by nearly 160 mV compared to pure pristine MnO2 (from 476 to 312 mV) at 10 mA cm-2, and a small Tafel slope of 89 mV dec-1. Moreover, it demonstrates excellent durability over a 122 h stability test. The introduction of O vacancies and incorporation of N not only fine-tune the electronic structure of MnO2, increasing the Mn3+ content to enhance overall activity, but also play a crucial role in stabilizing Mn3+, thereby leading to exceptional stability over time. Subsequently, density functional theory calculations validate the optimized electronic structure of MnO2 achieved through the two engineering methods, effectively lowering the intermediate adsorption free energy barrier. Our synergistic approach, utilizing nitrogen plasma treatment, opens a pathway to concurrently enhance the activity and stability of OER electrocatalysts, applicable not only to Mn-based but also to other transition metal oxides.
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Affiliation(s)
- Yang Liu
- School of Material Science and Engineering, Hebei University of Technology, Dingzigu Road 1, Tianjin 300130, P. R. China
- Hebei Key Laboratory of Boron Nitride Micro and Nano Materials, Guangrongdao Road 29, Tianjin 300130, P. R. China
| | - Shiqing Zhang
- School of Material Science and Engineering, Hebei University of Technology, Dingzigu Road 1, Tianjin 300130, P. R. China
- Hebei Key Laboratory of Boron Nitride Micro and Nano Materials, Guangrongdao Road 29, Tianjin 300130, P. R. China
| | - Shaokai Ma
- School of Material Science and Engineering, Hebei University of Technology, Dingzigu Road 1, Tianjin 300130, P. R. China
- Hebei Key Laboratory of Boron Nitride Micro and Nano Materials, Guangrongdao Road 29, Tianjin 300130, P. R. China
| | - Xinyu Sun
- School of Material Science and Engineering, Hebei University of Technology, Dingzigu Road 1, Tianjin 300130, P. R. China
- Hebei Key Laboratory of Boron Nitride Micro and Nano Materials, Guangrongdao Road 29, Tianjin 300130, P. R. China
| | - Ying Wang
- School of Material Science and Engineering, Hebei University of Technology, Dingzigu Road 1, Tianjin 300130, P. R. China
- Hebei Key Laboratory of Boron Nitride Micro and Nano Materials, Guangrongdao Road 29, Tianjin 300130, P. R. China
| | - Fang Liu
- School of Material Science and Engineering, Hebei University of Technology, Dingzigu Road 1, Tianjin 300130, P. R. China
- Hebei Key Laboratory of Boron Nitride Micro and Nano Materials, Guangrongdao Road 29, Tianjin 300130, P. R. China
| | - Ying Li
- School of Material Science and Engineering, Hebei University of Technology, Dingzigu Road 1, Tianjin 300130, P. R. China
| | - Yuanhui Ma
- School of Material Science and Engineering, Hebei University of Technology, Dingzigu Road 1, Tianjin 300130, P. R. China
- Hebei Key Laboratory of Boron Nitride Micro and Nano Materials, Guangrongdao Road 29, Tianjin 300130, P. R. China
| | - Xuewen Xu
- School of Material Science and Engineering, Hebei University of Technology, Dingzigu Road 1, Tianjin 300130, P. R. China
| | - Yanming Xue
- School of Material Science and Engineering, Hebei University of Technology, Dingzigu Road 1, Tianjin 300130, P. R. China
- Hebei Key Laboratory of Boron Nitride Micro and Nano Materials, Guangrongdao Road 29, Tianjin 300130, P. R. China
| | - Chengchun Tang
- School of Material Science and Engineering, Hebei University of Technology, Dingzigu Road 1, Tianjin 300130, P. R. China
- Hebei Key Laboratory of Boron Nitride Micro and Nano Materials, Guangrongdao Road 29, Tianjin 300130, P. R. China
| | - Jun Zhang
- School of Material Science and Engineering, Hebei University of Technology, Dingzigu Road 1, Tianjin 300130, P. R. China
- Hebei Key Laboratory of Boron Nitride Micro and Nano Materials, Guangrongdao Road 29, Tianjin 300130, P. R. China
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Tippner S, Lechner P, González L, Mai S. Interplay between protonation and Jahn-Teller effects in a manganese vanadium cubane water oxidation catalyst. J Chem Phys 2024; 160:084306. [PMID: 38411230 DOI: 10.1063/5.0189673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 02/05/2024] [Indexed: 02/28/2024] Open
Abstract
Understanding the protonation behavior of metal-oxo water oxidation catalysts is essential to improve catalyst efficiency and long-term performance, as well as to tune their properties for specific applications. In this work, we explore the basicity and protonation effects of the highly active water oxidation catalyst [(Mn4O4) (V4O13) (OAc)3]3- using density functional theory. We computed the relative free energies of protonation in a systematic fashion for all symmetry-inequivalent O atoms, where the presence of multiple oxidation states from Mn4IV to Mn4III and a rich Jahn-Teller isomerism adds a significant amount of complexity. For high oxidation states, the compound behaves like some other polyoxometalates, showing protonation preferably at the terminal and μ2-bridging O atoms of the vanadate cap. However, upon reduction, eventually, the protonation preference switches to the cubane O atoms, mostly driven by a strong increase in basicity for O atoms located along the Jahn-Teller axes. Our work further evidences that protonation can potentially lead to several chemical transformations, like disproportionation and charge transfer to vanadium, dissociation of ligands, or the opening of the cubane structure. Our simulated UV/Vis absorption spectra additionally provide valuable insights about how the protonation of the catalyst could be tracked experimentally. Overall, our analysis highlights the complexity involved in the protonation of heterometallic polyoxometalate clusters.
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Affiliation(s)
- Simon Tippner
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
- University of Vienna, Vienna Doctoral School in Chemistry (DoSChem), Währinger Str. 42, 1090 Vienna, Austria
| | - Patrick Lechner
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
| | - Leticia González
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
- Vienna Research Platform on Accelerating Photoreaction Discovery, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
| | - Sebastian Mai
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
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Schwiedrzik L, Rajkovic T, González L. Regeneration and Degradation in a Biomimetic Polyoxometalate Water Oxidation Catalyst. ACS Catal 2023; 13:3007-3019. [PMID: 36910868 PMCID: PMC9990072 DOI: 10.1021/acscatal.2c06301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/30/2023] [Indexed: 02/16/2023]
Abstract
Complete understanding of catalytic cycles is required to advance the design of water oxidation catalysts, but it is difficult to attain, due to the complex factors governing their reactivity and stability. In this study, we investigate the regeneration and degradation pathways of the highly active biomimetic water oxidation catalyst [Mn3+ 2Mn4+ 2V4O17(OAc)3]3-, thereby completing its catalytic cycle. Beginning with the deactivated species [Mn3+ 4V4O17(OAc)2]4- left over after O2 evolution, we scrutinize a network of reaction intermediates belonging to two alternative water oxidation cycles. We find that catalyst regeneration to the activated species [Mn4+ 4V4O17(OAc)2(OH)(H2O)]- proceeds via oxidation of each Mn center, with one water ligand being bound during the first oxidation step and a second water ligand being bound and deprotonated during the final oxidation step. ΔΔG values for this last oxidation are consistent with previous experimental results, while regeneration within an alternative catalytic cycle was found to be thermodynamically unfavorable. Extensive in silico sampling of catalyst structures also revealed two degradation processes: cubane opening and ligand dissociation, both of which have low barriers at highly reduced states of the catalyst due to the presence of Jahn-Teller effects. These mechanistic insights are expected to spur the development of more efficient and stable Mn cubane water oxidation catalysts.
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Affiliation(s)
- Ludwig Schwiedrzik
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria.,Vienna Doctoral School in Chemistry (DoSChem), University of Vienna, Währinger Str. 42, 1090 Vienna, Austria
| | - Tina Rajkovic
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria
| | - Leticia González
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria
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Li M, Liao RZ. Water Oxidation Catalyzed by a Bioinspired Tetranuclear Manganese Complex: Mechanistic Study and Prediction. CHEMSUSCHEM 2022; 15:e202200187. [PMID: 35610183 DOI: 10.1002/cssc.202200187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 05/23/2022] [Indexed: 06/15/2023]
Abstract
Density functional theory calculations were utilized to elucidate the water oxidation mechanism catalyzed by polyanionic tetramanganese complex a [MnIII 3 MnIV O3 (CH3 COO)3 (A-α-SiW9 O34 )]6- . Theoretical results indicated that catalytic active species 1 (Mn4 III,III,IV,IV ) was formed after O2 formation in the first turnover. From 1, three sequential proton-coupled electron transfer (PCET) oxidations led to the MnIV -oxyl radical 4 (Mn4 IV,IV,IV,IV -O⋅). Importantly, 4 had an unusual butterfly-shaped Mn2 O2 core for the two substrate-coordinated Mn sites, which facilitated O-O bond formation via direct coupling of the oxyl radical and the adjacent MnIV -coordinated hydroxide to produce the hydroperoxide intermediate Int1 (Mn4 III,IV,IV,IV -OOH). This step had an overall energy barrier of 24.9 kcal mol-1 . Subsequent PCET oxidation of Int1 to Int2 (Mn4 III,IV,IV,IV -O2 ⋅) enabled the O2 release in a facile process. Furthermore, apart from the Si-centered complex, computational study suggested that tetramanganese polyoxometalates with Ge, P, and S could also catalyze the water oxidation process, where those bearing P and S likely present higher activities.
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Affiliation(s)
- Man Li
- 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
| | - 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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Schwiedrzik L, Brieskorn V, González L. Flexibility Enhances Reactivity: Redox Isomerism and Jahn-Teller Effects in a Bioinspired Mn 4O 4 Cubane Water Oxidation Catalyst. ACS Catal 2021; 11:13320-13329. [PMID: 34777908 PMCID: PMC8576808 DOI: 10.1021/acscatal.1c03566] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 09/28/2021] [Indexed: 12/25/2022]
Abstract
Understanding how water oxidation to molecular oxygen proceeds in molecular metal-oxo catalysts is a challenging endeavor due to their structural complexity. In this report, we unravel the water oxidation mechanism of the highly active water oxidation catalyst [Mn4V4O17(OAc)3]3-, a polyoxometalate catalyst with a [Mn4O4]6+ cubane core reminiscent of the natural oxygen-evolving complex. Starting from the activated species [Mn4 4+V4O17(OAc)2(H2O)(OH)]1-, we scrutinized multiple pathways to find that water oxidation proceeds via a sequential proton-coupled electron transfer (PCET), O-O bond formation, another PCET, an intramolecular electron transfer, and another PCET resulting in O2 evolution, with a predicted thermodynamic overpotential of 0.71 V. An in-depth investigation of the O-O bond formation process revealed an essential interplay between redox isomerism and Jahn-Teller effects, responsible for enhancing reactivity in the catalytic cycle. This is achieved by redistributing electrons between metal centers and weakening relevant bonds through Jahn-Teller distortions, introducing flexibility to the otherwise rigid cubane core of the catalyst. These mechanistic insights are expected to advance the design of efficient bioinspired Mn cubane water-splitting catalysts.
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Affiliation(s)
- Ludwig Schwiedrzik
- Institute of Theoretical
Chemistry, Faculty of Chemistry, University
of Vienna, Währinger Straße 17, 1090 Vienna, Austria
| | - Vera Brieskorn
- Institute of Theoretical
Chemistry, Faculty of Chemistry, University
of Vienna, Währinger Straße 17, 1090 Vienna, Austria
| | - Leticia González
- Institute of Theoretical
Chemistry, Faculty of Chemistry, University
of Vienna, Währinger Straße 17, 1090 Vienna, Austria
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