| Atomistic Structure of Cobalt-Phosphate Nanoparticles for Catalytic Water Oxidation. | |
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MedLine Citation:
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PMID: 23145574 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Solar-driven water splitting is a key photochemical reaction that underpins the feasible and sustainable production of solar fuels. An amorphous cobalt-phosphate catalyst (Co-Pi) based on earth-abundant elements has been recently reported to efficiently promote water oxidation to protons and dioxygen, a main bottleneck for the overall process. The structure of this material remains largely unknown. We here exploit ab initio and classical atomistic simulations combined with metadynamics to build a realistic and statistically meaningful model of Co-Pi nanoparticles. We demonstrate the emergence and stability of molecular-size ordered crystallites in nanoparticles initially formed by a disordered Co-O network and phosphate groups. The stable crystallites consist of bis-oxo bridged Co centers that assemble into layered structures (edge-sharing CoO6 octahedra) as well as in corner- and face-sharing cubane units. These layered and cubane motifs coexist in the crystallites, which always incorporate disordered phosphate groups at the edges. Our computational nanoparticles, although limited in size to ~1nm, can contain more than one crystallite and incorporate up to 18 Co centers in the cubane/layered structures. The crystallites are structurally stable up to high temperatures. We simulate the extended X-ray absorption fine structure (EXAFS) of our nanoparticles. Those containing several complete and incomplete cubane motifs - which are believed to be essential for the catalytic activity - display a very good agreement with the experimental EXAFS spectra of Co-Pi grains. We propose that the crystallites in our nanoparticles are reliable structural models of the Co-Pi catalyst surface. They will be useful to reveal the origin of the catalytic efficiency of these novel water-oxidation catalysts. |
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Authors:
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Xiao Liang Hu; Simone Piccinin; Alessandro Laio; Stefano Fabris |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2012-11-12 |
Journal Detail:
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Title: ACS nano Volume: - ISSN: 1936-086X ISO Abbreviation: ACS Nano Publication Date: 2012 Nov |
Date Detail:
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Created Date: 2012-11-13 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101313589 Medline TA: ACS Nano Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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