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Lang SM, Zimmermann N, Bernhardt TM, Barnett RN, Yoon B, Landman U. Size, Stoichiometry, Dimensionality, and Ca Doping of Manganese Oxide-Based Water Oxidation Clusters: An Oxyl/Hydroxy Mechanism for Oxygen-Oxygen Coupling. J Phys Chem Lett 2021; 12:5248-5255. [PMID: 34048261 DOI: 10.1021/acs.jpclett.1c01299] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Gas-phase ion-trap reactivity experiments and density functional simulations reveal that water oxidation to H2O2 mediated by (calcium) manganese oxide clusters proceeds via formation of a terminal oxyl radical followed by oxyl/hydroxy O-O coupling. This mechanism is predicted to be energetically feasible for Mn2Oy+ (y = 2-4) and the binary CaMn3O4+, in agreement with the experimental observations. In contrast, the reaction does not proceed for the tetramanganese oxides Mn4Oy+ (y = 4-6) under these experimental conditions. This is attributed to the high fluxionality of the tetramanganese clusters, resulting in the instability of the terminal oxyl radical as well as an energetically unfavorable change of the spin state required for H2O2 formation. Ca doping, yielding a symmetry-broken lower-symmetry three-dimensional (3D) CaMn3O4+ cluster, results in structural stabilization of the oxyl radical configuration, accompanied by a favorable coupling between potential energy surfaces with different spin states, thus enabling the cluster-mediated water oxidation reaction and H2O2 formation.
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Affiliation(s)
- Sandra M Lang
- Institute of Surface Chemistry and Catalysis, University of Ulm, 89069 Ulm, Germany
| | - Nina Zimmermann
- Institute of Surface Chemistry and Catalysis, University of Ulm, 89069 Ulm, Germany
| | - Thorsten M Bernhardt
- Institute of Surface Chemistry and Catalysis, University of Ulm, 89069 Ulm, Germany
| | - Robert N Barnett
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, United States
| | - Bokwon Yoon
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, United States
| | - Uzi Landman
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, United States
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Chakrapani V. Probing Active Sites and Reaction Intermediates of Electrocatalysis Through Confocal Near-Infrared Photoluminescence Spectroscopy: A Perspective. Front Chem 2020; 8:327. [PMID: 32411668 PMCID: PMC7199742 DOI: 10.3389/fchem.2020.00327] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 03/31/2020] [Indexed: 12/19/2022] Open
Abstract
Electrocatalytic reactions such as oxygen evolution (OER) and oxygen reduction reactions (ORR) are one of the most complex heterogeneous charge transfer processes because of the involvement of multiple proton-coupled-electron transfer steps over a narrow potential range and the formation/breaking of oxygen-oxygen bonds. Obtaining a clear mechanistic picture of these reactions on some highly active strongly-correlated oxides such as MnOx, NiOx, and IrOx has been challenging due to the inherent limitations of the common spectroscopic tools used for probing the reactive intermediates and active sites. This perspective article briefly summarizes some of the key challenges encountered in such probes and describes some of unique advantages of confocal near-infrared photoluminescence (NIR-PL) technique for probing surface and bulk metal cation states under in-situ and ex-situ electrochemical polarization studies. Use of this technique opens up a new avenue for studying changes in the electronic structure of metal oxides occurring as a result of perturbation of defect equilibria, which is crucial in a broad range of heterogeneous systems such as catalysis, photocatalysis, mineral redox chemistry, and batteries.
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Affiliation(s)
- Vidhya Chakrapani
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, United States.,Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, NY, United States
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3
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Zimmermann N, Bernhardt TM, Bakker JM, Landman U, Lang SM. Infrared photodissociation spectroscopy of di-manganese oxide cluster cations. Phys Chem Chem Phys 2019; 21:23922-23930. [PMID: 31661104 DOI: 10.1039/c9cp04586d] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Infrared multiple-photon dissociation (IR-MPD) spectroscopy and density functional theory (DFT) calculations have been employed to elucidate the geometric structure of a series of di-manganese oxide clusters Mn2Ox+ (x = 4-7). The theoretical exploration predicts that all investigated clusters contain a rhombus-like Mn2O2 core with up to four, terminally bound, oxygen atoms. The short Mn-O bond length of the terminal oxygen atoms of ≤1.58 Å indicates triple bond character instead of oxyl radical formation. However, the IR-MPD spectra reveal that higher energy isomers with up to two O2 molecules η2-coordinated to the cluster core can be kinetically trapped under the given experimental conditions. In these complexes, all O2 units are activated to superoxide species. In addition, the sequential increase of the oxygen content in the cluster allows for a controlled increase of the positive charge localized on the Mn atoms reaching a maximum for Mn2O7+.
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Affiliation(s)
- Nina Zimmermann
- Institute of Surface Chemistry and Catalysis, University of Ulm, Albert-Einstein-Allee 47, 89069 Ulm, Germany.
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Weerawardene KLDM, Aikens CM. Theoretical Investigation of Water Oxidation Mechanism on Pure Manganese and Ca-Doped Bimetal Oxide Complexes. J Phys Chem A 2019; 123:6152-6159. [DOI: 10.1021/acs.jpca.9b02652] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Christine M. Aikens
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, United States
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Jiao Y, Sharpe R, Lim T, Niemantsverdriet JWH, Gracia J. Photosystem II Acts as a Spin-Controlled Electron Gate during Oxygen Formation and Evolution. J Am Chem Soc 2017; 139:16604-16608. [PMID: 29064697 DOI: 10.1021/jacs.7b07634] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The oxygen evolution complex (OEC) of photosystem II (PSII) is intrinsically more active than any synthetic alternative for the oxygen evolution reaction (OER). A crucial question to solve for the progress of artificial photosynthesis is to understand the influential interactions during water oxidation in PSII. We study the principles of interatomic electron transfer steps in OER, with emphasis on exchange interactions, revealing the influence of delocalizing ferromagnetic spin potentials during the catalytic process. The OEC is found to be an exchange coupled mixed-valence electron-spin acceptor where its orbital physics determine the unique activity of PSII. The two unpaired electrons needed in the triplet O2 molecule interact with the high spin state of the catalyst via exchange interactions; the optimal ferromagnetic catalyst and the resulting radical intermediates are spin paired. As a result, the active center of the CaMn4O5 cofactor, stimulated by the driving potential provided by photons, works as a spin valve to accelerate the formation and release of O2 from diamagnetic H2O.
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Affiliation(s)
- Yunzhe Jiao
- SynCat@Beijing, Synfuels China Technology Co. Ltd. , Beijing 101407, China
| | - Ryan Sharpe
- SynCat@Beijing, Synfuels China Technology Co. Ltd. , Beijing 101407, China
| | - Tingbin Lim
- SynCat@Beijing, Synfuels China Technology Co. Ltd. , Beijing 101407, China
| | - J W Hans Niemantsverdriet
- SynCat@Beijing, Synfuels China Technology Co. Ltd. , Beijing 101407, China.,SynCat@DIFFER, Syngaschem BV , Eindhoven 5600 HH, The Netherlands
| | - Jose Gracia
- SynCat@Beijing, Synfuels China Technology Co. Ltd. , Beijing 101407, China.,SynCat@DIFFER, Syngaschem BV , Eindhoven 5600 HH, The Netherlands
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Petrova J, Ivanova A, Tadjer A. Density Functional Theory Assessment of the Environment Polarity Effect on Polyaniline-Water Coupling. J Phys Chem A 2017; 121:6327-6335. [PMID: 28742353 DOI: 10.1021/acs.jpca.7b04663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Crystallization water plays an important role in the self-organization of oligomer chains in conducting polyaniline. In order to quantify the interaction between emeraldine salt and such a water, models containing a tetramer in bipolaronic or polaronic form, chloride counterions, and an explicit water molecule are used. Different initial positions of water with respect to the oligomer chain-tangential and vertical-are considered. Various media are simulated by introducing an implicit solvent continuum of decreasing polarity. The DFT-D3/PCM computational approach is employed to examine the behavior of the systems in several aspects-the role of the explicit water position and the effect of the environment polarity on the spatial structure, energetics, charge distribution, and the frontier molecular orbital energies. The strength of hydrogen bonding and the patterns of charge redistribution invoked by the water molecule are discussed. The study establishes trend lines in the variation of the molecular characteristics upon change of milieu as a tool for control of the self-assembly process. The results show that chains interact more efficiently with tangentially placed water. The influence of the environment polarity is minor and is mainly expressed in slight shortening of the intermolecular distances and mild decrease of the group charges of the system components with reduction of polarity.
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Affiliation(s)
- Jasmina Petrova
- Faculty of Chemistry and Pharmacy, University of Sofia , 1 James Bourchier Boulevard, 1164 Sofia, Bulgaria
| | - Anela Ivanova
- Faculty of Chemistry and Pharmacy, University of Sofia , 1 James Bourchier Boulevard, 1164 Sofia, Bulgaria
| | - Alia Tadjer
- Faculty of Chemistry and Pharmacy, University of Sofia , 1 James Bourchier Boulevard, 1164 Sofia, Bulgaria
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Ray M, Saha A, Raghavachari K. Hydrogen evolution from water using Mo–oxide clusters in the gas phase: DFT modeling of a complete catalytic cycle using a Mo2O4−/Mo2O5− cluster couple. Phys Chem Chem Phys 2016; 18:25687-25692. [DOI: 10.1039/c6cp04259g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydrogen evolution from water using sacrificial reagents and Mo–oxide cluster anions has been explored. The internal energy preservation within the clusters plays a key role in the catalytic cycle.
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Affiliation(s)
- Manisha Ray
- Department of Chemistry
- Indiana University
- Bloomington
- USA
| | - Arjun Saha
- Department of Chemistry
- Indiana University
- Bloomington
- USA
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