Articles producció científica> Química Física i Inorgànica

Tetracobalt-polyoxometalate catalysts for water oxidation: Key mechanistic details

  • Identification data

    Identifier: PC:3138
    Authors:
    López, J.Musaev, D.Craig, H.Galán-Mascarós, J. R.Carbó, J.Poblet, J. M:
    Abstract:
    Filiació URV: SI
  • Others:

    Author, as appears in the article.: López, J. ; Musaev, D. ; Craig, H. ; Galán-Mascarós, J. R. ; Carbó, J. ; Poblet, J. M:
    Department: Química Física i Inorgànica
    URV's Author/s: LÓPEZ FERNÁNDEZ, JAVIER; Musaev, D. ; Craig, H. ; Galán-Mascarós, J. R. ; CARBÓ MARTIN, JORGE JUAN; POBLET RIUS, JOSEP MARIA
    Keywords: polyoxometalates water oxidation catalysis DFT
    Abstract: A mechanism of water oxidation catalyzed by the carbon-free tetra-Co containing polyoxometalates [Co4(H2O)2(PW9O34)2]10− (PCo4) and [Co4(H2O)2(VW9O34)2]10− (VCo4) is elucidated by DFT calculations. Computational analysis for PCo4 suggests that a first PCET step may proceed via a sequential electron-then-proton transfer (ET + PT) pathway and leads to one electron oxidize species S1 (POM-CoIIIOH). In contrast, the second PCET, which controls the potential required to form POM-CoIII active species S2 is clearly a concerted process. The overall S0 → S2 transformation is estimated to require less than 1.48 V and 1.62 V applied potential at pH = 8 for PCo4 and VCo4 anions, respectively. At operando conditions, with the presence of a buffer and with an applied potential above the threshold potential the two H-atom removal could take place via concerted pathways. These steps represent rapid pre-equilibria before the rate determining step, which corresponds to the OO bond formation. The key chemical step occurs via nucleophilic attack of an external water molecule to intermediate S2. We assume that this step governs the kinetics of the reaction. Comparison of the calculated energetics and electronic structures of intermediate species in the PCo4 and VCo4 catalyzed water oxidation cycle shows that coupling of d orbitals of V and Co atoms in VCo4 increases the oxidation potential of the Co-center. The orbital coupling is also responsible for the higher catalytic activity of VCo4 because it increases the electrophilicity of CoIII moiety in the key S2 species.
    Research group: Química Quàntica
    Thematic Areas: Química Química Chemistry
    licence for use: https://creativecommons.org/licenses/by/3.0/es/
    ISSN: 0021-9517
    Author identifier: 0000-0003-0322-6796; ; ; ; 0000-0002-3945-6721; 0000-0002-4533-0623
    Record's date: 2018-03-05
    Last page: 63
    Journal volume: 350
    Papper version: info:eu-repo/semantics/acceptedVersion
    Link to the original source: https://www.sciencedirect.com/science/article/pii/S0021951717301021?via%3Dihub
    Funding program: plan; Excelencia; CTQ2014-52774-P altres; Grupos Consolidados; 2014SGR199 altres; ICREA Academia
    Licence document URL: https://repositori.urv.cat/ca/proteccio-de-dades/
    Article's DOI: 10.1016/j.jcat.2017.03.018
    Entity: Universitat Rovira i Virgili
    Journal publication year: 2017
    First page: 56
    Publication Type: Article Artículo Article
  • Keywords:

    Aigua-Oxidació
    Catàlisi
    polyoxometalates
    water oxidation catalysis
    DFT
    Química
    Química
    Chemistry
    0021-9517
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