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Title: Potential-specific structure at the hematite-electrolyte interface

Abstract

The atomic-scale structure of interfaces between metal oxides and aqueous electrolytes controls their catalytic, geochemical, and corrosion behavior. Measurements that probe these interfaces in situ provide important details of ion and solvent arrangements, but atomically precise structural models do not exist for common oxide-electrolyte interfaces far from equilibrium. Using a novel cell, we measured the structure of the hematite (a-Fe 2O 3) (110$$\bar{2}$$)-electrolyte interface under controlled electrochemical bias using synchrotron crystal truncation rod X ray scattering. At increasingly cathodic potentials, charge-compensating protonation of surface oxygen groups increases the coverage of specifically bound water while adjacent water layers displace outwardly and became disordered. Returning to open circuit potential leaves the surface in a persistent metastable protonation state. The flux of current and ions at applied potential is thus regulated by a unique interfacial electrolyte environment, suggesting that electrical double layer models should be adapted to the dynamically changing interfacial structure far from equilibrium.

Authors:
; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1422282
Report Number(s):
PNNL-SA-128852
Journal ID: ISSN 1616-3028; 49381; KC0302060
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Advanced Functional Materials (Online); Journal Volume: 28; Journal Issue: 8; Related Information: Article No. 1705618
Country of Publication:
United States
Language:
English
Subject:
geochemistry; electrochemistry; synchrotron; oxides; interface chemistry; Environmental Molecular Sciences Laboratory

Citation Formats

McBriarty, Martin E., Stubbs, Joanne, Eng, Peter, and Rosso, Kevin M. Potential-specific structure at the hematite-electrolyte interface. United States: N. p., 2018. Web. doi:10.1002/adfm.201705618.
McBriarty, Martin E., Stubbs, Joanne, Eng, Peter, & Rosso, Kevin M. Potential-specific structure at the hematite-electrolyte interface. United States. doi:10.1002/adfm.201705618.
McBriarty, Martin E., Stubbs, Joanne, Eng, Peter, and Rosso, Kevin M. Wed . "Potential-specific structure at the hematite-electrolyte interface". United States. doi:10.1002/adfm.201705618.
@article{osti_1422282,
title = {Potential-specific structure at the hematite-electrolyte interface},
author = {McBriarty, Martin E. and Stubbs, Joanne and Eng, Peter and Rosso, Kevin M.},
abstractNote = {The atomic-scale structure of interfaces between metal oxides and aqueous electrolytes controls their catalytic, geochemical, and corrosion behavior. Measurements that probe these interfaces in situ provide important details of ion and solvent arrangements, but atomically precise structural models do not exist for common oxide-electrolyte interfaces far from equilibrium. Using a novel cell, we measured the structure of the hematite (a-Fe2O3) (110$\bar{2}$)-electrolyte interface under controlled electrochemical bias using synchrotron crystal truncation rod X ray scattering. At increasingly cathodic potentials, charge-compensating protonation of surface oxygen groups increases the coverage of specifically bound water while adjacent water layers displace outwardly and became disordered. Returning to open circuit potential leaves the surface in a persistent metastable protonation state. The flux of current and ions at applied potential is thus regulated by a unique interfacial electrolyte environment, suggesting that electrical double layer models should be adapted to the dynamically changing interfacial structure far from equilibrium.},
doi = {10.1002/adfm.201705618},
journal = {Advanced Functional Materials (Online)},
number = 8,
volume = 28,
place = {United States},
year = {Wed Feb 21 00:00:00 EST 2018},
month = {Wed Feb 21 00:00:00 EST 2018}
}