Dataset Information

Water Breakup at Fe₂O₃-Hematite/Water Interfaces: Influence of External Electric Fields from Nonequilibrium Ab Initio Molecular Dynamics.

ABSTRACT: The dynamical properties of physically and chemically adsorbed water molecules at pristine hematite-(001) surfaces have been studied by means of nonequilibrium ab initio molecular dynamics (NE-AIMD) in the NVT ensemble at room temperature, in the presence of externally applied, uniform static electric fields of increasing intensity. The dissociation of water molecules to form chemically adsorbed species was scrutinized, in addition to charge redistribution and Grotthus proton hopping between water molecules. Dynamical properties of the adsorbed water molecules and OH^- and H₃O⁺ ions were gauged, such as the hydrogen bonds between protons in water molecules and the bridging oxygen atoms at the hematite surface, as well as the interactions between oxygen atoms in adsorbed water molecules and iron atoms at the hematite surface. The development of Helmholtz charge layers via water breakup at Fe₂O₃-hematite/water interfaces is also an interesting feature, with the development of protonic conduction on the surface and more bulk-like water.

SUBMITTER: Futera Z

PROVIDER: S-EPMC8397349 | biostudies-literature | 2021 Jul

REPOSITORIES: biostudies-literature

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Water Breakup at Fe2O3-Hematite/Water Interfaces: Influence of External Electric Fields from Nonequilibrium Ab Initio Molecular Dynamics.

Futera Zdenek Z English Niall J NJ

The journal of physical chemistry letters 20210716 29

The dynamical properties of physically and chemically adsorbed water molecules at pristine hematite-(001) surfaces have been studied by means of nonequilibrium ab initio molecular dynamics (NE-AIMD) in the NVT ensemble at room temperature, in the presence of externally applied, uniform static electric fields of increasing intensity. The dissociation of water molecules to form chemically adsorbed species was scrutinized, in addition to charge redistribution and Grotthus proton hoppi ...[more]

PMID: 34270253

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Project description:In the exploration of the optimal material for achieving the photoelectrochemical dissociation of water into hydrogen, hematite (α-Fe2O3) emerges as a highly promising candidate for proof-of-concept demonstrations. Recent studies suggest that the concurrent application of external electric fields could enhance the photoelectrochemical (PEC) process. To delve into this, we conducted nonequilibrium ab initio molecular dynamics (NE-AIMD) simulations in this study, focusing on hematite-water interfaces at room temperature under progressively stronger electric fields. Our findings reveal intriguing evidence of water molecule adsorption and dissociation, as evidenced by an analysis of the structural properties of the hydrated layered surface of the hematite-water interface. Additionally, we scrutinized intermolecular structures using radial distribution functions (RDFs) to explore the interaction between the hematite slab and water. Notably, the presence of a Grotthuss hopping mechanism became apparent as the electric field strength increased. A comprehensive discussion based on intramolecular geometry highlighted aspects such as hydrogen-bond lengths, H-bond angles, average H-bond numbers, and the observed correlation existing among the hydrogen-bond strength, bond-dissociation energy, and H-bond lifetime. Furthermore, we assessed the impact of electric fields on the librational, bending, and stretching modes of hydrogen atoms in water by calculating the vibrational density of states (VDOS). This analysis revealed distinct field effects for the three characteristic band modes, both in the bulk region and at the hematite-water interface. We also evaluated the charge density of active elements at the aqueous hematite surface, delving into field-induced electronic charge-density variations through the Hirshfeld charge density analysis of atomic elements. Throughout this work, we drew clear distinctions between parallel and antiparallel field alignments at the hematite-water interface, aiming to elucidate crucial differences in local behavior for each surface direction of the hematite-water interface.

Dataset Information

Water Breakup at Fe₂O₃-Hematite/Water Interfaces: Influence of External Electric Fields from Nonequilibrium Ab Initio Molecular Dynamics.

Publications

Water Breakup at Fe<sub>2</sub>O<sub>3</sub>-Hematite/Water Interfaces: Influence of External Electric Fields from Nonequilibrium <i>Ab Initio</i> Molecular Dynamics.

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