Catalytic water dissociation by greigite Fe3S4surfaces: density functional theory study

Roldan Martinez, Alberto ORCID: https://orcid.org/0000-0003-0353-9004 and de Leeuw, Nora ORCID: https://orcid.org/0000-0002-8271-0545 2016. Catalytic water dissociation by greigite Fe3S4surfaces: density functional theory study. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472 (2188) , 20160080. 10.1098/rspa.2016.0080

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Abstract

The iron sulfide mineral greigite, Fe3S4, has shown promising capability as a hydrogenating catalyst, in particular in the reduction of carbon dioxide to produce small organic molecules under mild conditions. We employed density functional theory calculations to investigate the {001},{011} and {111} surfaces of this iron thiospinel material, as well as the production of hydrogen ad-atoms from the dissociation of water molecules on the surfaces. We systematically analysed the adsorption geometries and the electronic structure of both bare and hydroxylated surfaces. The sulfide surfaces presented a higher flexibility than the isomorphic oxide magnetite, Fe3O4, allowing perpendicular movement of the cations above or below the top atomic sulfur layer. We considered both molecular and dissociative water adsorption processes, and have shown that molecular adsorption is the predominant state on these surfaces from both a thermodynamic and kinetic point of view. We considered a second molecule of water which stabilizes the system mainly by H-bonds, although the dissociation process remains thermodynamically unfavourable. We noted, however, synergistic adsorption effects on the Fe3S4{001} owing to the presence of hydroxyl groups. We concluded that, in contrast to Fe3O4, molecular adsorption of water is clearly preferred on greigite surfaces.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Advanced Research Computing @ Cardiff (ARCCA) Chemistry
Publisher:	Royal Society
ISSN:	1364-5021
Funders:	Engineering and Physical Sciences Research Council
Date of First Compliant Deposit:	8 April 2016
Date of Acceptance:	11 March 2016
Last Modified:	10 Nov 2024 18:15
URI:	https://orca.cardiff.ac.uk/id/eprint/88962

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