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Title: XPS determination of Mn oxidation states in Mn (hydr)oxides

Abstract

Hydrous manganese oxides are an important class of minerals that help regulate the geochemical redox cycle in near-surface environments and are also considered to be promising catalysts for energy applications such as the oxidation of water. A complete characterization of these minerals is required to better understand their catalytic activity. In this contribution an empirical methodology using X-ray photoelectron spectroscopy (XPS) is developed to quantify the oxidation state of hydrous multivalent manganese oxides with an emphasis on birnessite, a common layered structure that occurs readily in Nature but is also the oxidized endmember in biomimetic water-oxidation catalysts. The Mn2p3/2, Mn3p, and Mn3s lines of near monovalent Mn(II), Mn(III), and Mn(IV) oxides were fit with component peaks; after the best fit was obtained the relative widths, heights and binding energies of the components were fixed. Unknown multivalent samples were fit such that binding energies, intensities, and widths of each oxidation state, composed of a packet of correlated component peaks, were allowed vary. whereas widths were constrained to maintain the difference between the standards. Both average and individual mole fraction oxidation states for all three energy levels were strongly correlated with close agreement between Mn3s and Mn3p, whereas Mn2p3/2 gave systematically moremore » reduced results. Limited stoichiometric analyses were consistent with Mn3p and Mn3s. Further, evidence indicates the shape of the Mn3p line was less sensitive to the bonding environment than Mn2p. Consequently, fitting the Mn3p and Mn3s lines yields robust quantification of oxidation states over a range of hydrous Mn oxide polytypes and compositions. In contrast, a common method for determining oxidation states that utilizes the multiplet splitting of the Mn3s line is not appropriate for birnessites.« less

Authors:
; ; ; ORCiD logo;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Biological and Environmental Research (BER)
OSTI Identifier:
1254570
Report Number(s):
PNNL-SA-113206
Journal ID: ISSN 0169-4332; 47509; 48389; KC0302060
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Applied Surface Science
Additional Journal Information:
Journal Volume: 366; Journal ID: ISSN 0169-4332
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
Manganese, birnessite, oxidation state, XPS, methodology; Environmental Molecular Sciences Laboratory

Citation Formats

Ilton, Eugene S., Post, Jeffrey E., Heaney, Peter J., Ling, Florence T., and Kerisit, Sebastien N. XPS determination of Mn oxidation states in Mn (hydr)oxides. United States: N. p., 2016. Web. doi:10.1016/j.apsusc.2015.12.159.
Ilton, Eugene S., Post, Jeffrey E., Heaney, Peter J., Ling, Florence T., & Kerisit, Sebastien N. XPS determination of Mn oxidation states in Mn (hydr)oxides. United States. https://doi.org/10.1016/j.apsusc.2015.12.159
Ilton, Eugene S., Post, Jeffrey E., Heaney, Peter J., Ling, Florence T., and Kerisit, Sebastien N. 2016. "XPS determination of Mn oxidation states in Mn (hydr)oxides". United States. https://doi.org/10.1016/j.apsusc.2015.12.159.
@article{osti_1254570,
title = {XPS determination of Mn oxidation states in Mn (hydr)oxides},
author = {Ilton, Eugene S. and Post, Jeffrey E. and Heaney, Peter J. and Ling, Florence T. and Kerisit, Sebastien N.},
abstractNote = {Hydrous manganese oxides are an important class of minerals that help regulate the geochemical redox cycle in near-surface environments and are also considered to be promising catalysts for energy applications such as the oxidation of water. A complete characterization of these minerals is required to better understand their catalytic activity. In this contribution an empirical methodology using X-ray photoelectron spectroscopy (XPS) is developed to quantify the oxidation state of hydrous multivalent manganese oxides with an emphasis on birnessite, a common layered structure that occurs readily in Nature but is also the oxidized endmember in biomimetic water-oxidation catalysts. The Mn2p3/2, Mn3p, and Mn3s lines of near monovalent Mn(II), Mn(III), and Mn(IV) oxides were fit with component peaks; after the best fit was obtained the relative widths, heights and binding energies of the components were fixed. Unknown multivalent samples were fit such that binding energies, intensities, and widths of each oxidation state, composed of a packet of correlated component peaks, were allowed vary. whereas widths were constrained to maintain the difference between the standards. Both average and individual mole fraction oxidation states for all three energy levels were strongly correlated with close agreement between Mn3s and Mn3p, whereas Mn2p3/2 gave systematically more reduced results. Limited stoichiometric analyses were consistent with Mn3p and Mn3s. Further, evidence indicates the shape of the Mn3p line was less sensitive to the bonding environment than Mn2p. Consequently, fitting the Mn3p and Mn3s lines yields robust quantification of oxidation states over a range of hydrous Mn oxide polytypes and compositions. In contrast, a common method for determining oxidation states that utilizes the multiplet splitting of the Mn3s line is not appropriate for birnessites.},
doi = {10.1016/j.apsusc.2015.12.159},
url = {https://www.osti.gov/biblio/1254570}, journal = {Applied Surface Science},
issn = {0169-4332},
number = ,
volume = 366,
place = {United States},
year = {Tue Mar 01 00:00:00 EST 2016},
month = {Tue Mar 01 00:00:00 EST 2016}
}