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  • 1
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2017
    In:  Proceedings of the National Academy of Sciences Vol. 114, No. 8 ( 2017-02-21), p. 1801-1805
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 114, No. 8 ( 2017-02-21), p. 1801-1805
    Abstract: Understanding adsorbed water and its dissociation to surface hydroxyls on oxide surfaces is key to unraveling many physical and chemical processes, yet the barrier for its deprotonation has never been measured. In this study, we present direct evidence for water dissociation equilibrium on rutile-TiO 2 (110) by combining supersonic molecular beam, scanning tunneling microscopy (STM), and ab initio molecular dynamics. We measure the deprotonation/protonation barriers of 0.36 eV and find that molecularly bound water is preferred over the surface-bound hydroxyls by only 0.035 eV. We demonstrate that long-range electrostatic fields emanating from the oxide lead to steering and reorientation of the molecules approaching the surface, activating the O–H bonds and inducing deprotonation. The developed methodology for studying metastable reaction intermediates prepared with a high-energy molecular beam in the STM can be readily extended to other systems to clarify a wide range of important bond activation processes.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2017
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 2
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 116, No. 9 ( 2019-02-26), p. 3572-3577
    Abstract: Cytochrome c oxidase (C c O) reduces dioxygen to water and harnesses the chemical energy to drive proton translocation across the inner mitochondrial membrane by an unresolved mechanism. By using time-resolved serial femtosecond crystallography, we identified a key oxygen intermediate of bovine C c O. It is assigned to the P R -intermediate, which is characterized by specific redox states of the metal centers and a distinct protein conformation. The heme a 3 iron atom is in a ferryl (Fe 4+ = O 2− ) configuration, and heme a and Cu B are oxidized while Cu A is reduced. A Helix-X segment is poised in an open conformational state; the heme a farnesyl sidechain is H-bonded to S382, and loop-I-II adopts a distinct structure. These data offer insights into the mechanism by which the oxygen chemistry is coupled to unidirectional proton translocation.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2019
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2021
    In:  Proceedings of the National Academy of Sciences Vol. 118, No. 4 ( 2021-01-26)
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 118, No. 4 ( 2021-01-26)
    Abstract: Hierarchically ordered oxides are of critical importance in material science and catalysis. Unfortunately, the design and synthesis of such systems remains a key challenge to realizing their potential. In this study, we demonstrate how the deposition of small oligomeric (MoO 3 ) 1–6 clusters—formed by the facile sublimation of MoO 3 powders—leads to the self-assembly of locally ordered arrays of immobilized mono-oxo (MoO 3 ) 1 species on anatase TiO 2 (101). Using both high-resolution imaging and theoretical calculations, we reveal the dynamic behavior of the oligomers as they spontaneously decompose at room temperature, with the TiO 2 surface acting as a template for the growth of this hierarchically structured oxide. Transient mobility of the oligomers on both bare and (MoO 3 ) 1 -covered TiO 2 (101) areas is identified as key to the formation of a complete (MoO 3 ) 1 overlayer with a saturation coverage of one (MoO 3 ) 1 per two undercoordinated surface Ti sites. Simulations reveal a dynamic coupling of the reaction steps to the TiO 2 lattice fluctuations, the absence of which kinetically prevents decomposition. Further experimental and theoretical characterizations demonstrate that (MoO 3 ) 1 within this material are thermally stable up to 500 K and remain chemically identical with a single empty gap state produced within the TiO 2 band structure. Finally, we see that the constituent (MoO 3 ) 1 of this material show no proclivity for step and defect sites, suggesting they can reliably be grown on the (101) facet of TiO 2 nanoparticles without compromising their chemistry.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2021
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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