A DFT+U investigation of hydrogen adsorption on the LaFeO3(010) surface

Isaac W. Boateng; Richard Tia; Evans Adei; Nelson Y. Dzade; C. Richard A. Catlow; Nora H. De Leeuw

doi:10.1039/c6cp08698e

A DFT+U investigation of hydrogen adsorption on the LaFeO₃(010) surface

Isaac W. Boateng, Richard Tia, Evans Adei, Nelson Y. Dzade, C. Richard A. Catlow, Nora H. De Leeuw

John and Willie Leone Department of Energy & Mineral Engineering (EME)

Research output: Contribution to journal › Article › peer-review

35 Scopus citations

Abstract

The ABO₃ perovskite lanthanum ferrite (LaFeO₃) is a technologically important electrode material for nickel-metal hydride batteries, energy storage and catalysis. However, the electrochemical hydrogen adsorption mechanism on LaFeO₃ surfaces remains under debate. In the present study, we have employed spin-polarized density functional theory calculations, with the Hubbard U correction (DFT+U), to unravel the adsorption mechanism of H₂ on the LaFeO₃(010) surface. We show from our calculated adsorption energies that the preferred site for H₂ adsorption is the Fe-O bridge site, with an adsorption energy of -1.18 eV (including the zero point energy), which resulted in the formation of FeOH and FeH surface species. H₂ adsorption at the surface oxygen resulted in the formation of a water molecule, which leaves the surface to create an oxygen vacancy. The H₂ molecule is found to interact weakly with the Fe and La sites, where it is only physisorbed. The electronic structures of the surface-adsorption systems are discussed via projected density of state and Löwdin population analyses. The implications of the calculated adsorption strengths and structures are discussed in terms of the improved design of nickel-metal hydride (Ni-MH) battery prototypes based on LaFeO₃.

Original language	English (US)
Pages (from-to)	7399-7409
Number of pages	11
Journal	Physical Chemistry Chemical Physics
Volume	19
Issue number	10
DOIs	https://doi.org/10.1039/c6cp08698e
State	Published - 2017

All Science Journal Classification (ASJC) codes

General Physics and Astronomy
Physical and Theoretical Chemistry

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10.1039/c6cp08698e

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title = "A DFT+U investigation of hydrogen adsorption on the LaFeO3(010) surface",

abstract = "The ABO3 perovskite lanthanum ferrite (LaFeO3) is a technologically important electrode material for nickel-metal hydride batteries, energy storage and catalysis. However, the electrochemical hydrogen adsorption mechanism on LaFeO3 surfaces remains under debate. In the present study, we have employed spin-polarized density functional theory calculations, with the Hubbard U correction (DFT+U), to unravel the adsorption mechanism of H2 on the LaFeO3(010) surface. We show from our calculated adsorption energies that the preferred site for H2 adsorption is the Fe-O bridge site, with an adsorption energy of -1.18 eV (including the zero point energy), which resulted in the formation of FeOH and FeH surface species. H2 adsorption at the surface oxygen resulted in the formation of a water molecule, which leaves the surface to create an oxygen vacancy. The H2 molecule is found to interact weakly with the Fe and La sites, where it is only physisorbed. The electronic structures of the surface-adsorption systems are discussed via projected density of state and L{\"o}wdin population analyses. The implications of the calculated adsorption strengths and structures are discussed in terms of the improved design of nickel-metal hydride (Ni-MH) battery prototypes based on LaFeO3.",

author = "Boateng, {Isaac W.} and Richard Tia and Evans Adei and Dzade, {Nelson Y.} and Catlow, {C. Richard A.} and {De Leeuw}, {Nora H.}",

note = "Funding Information: The authors gratefully acknowledge the UK's Royal Society and the Leverhulme Trust for a research grant under the Royal Society-Leverhulme Africa Award Scheme. EA, RT and IWB acknowledge the National Council for Tertiary Education, Ghana, for a TALIF research grant. Publisher Copyright: {\textcopyright} the Owner Societies 2017.",

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doi = "10.1039/c6cp08698e",

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AU - Boateng, Isaac W.

AU - Tia, Richard

AU - Adei, Evans

AU - Dzade, Nelson Y.

AU - Catlow, C. Richard A.

AU - De Leeuw, Nora H.

N1 - Funding Information: The authors gratefully acknowledge the UK's Royal Society and the Leverhulme Trust for a research grant under the Royal Society-Leverhulme Africa Award Scheme. EA, RT and IWB acknowledge the National Council for Tertiary Education, Ghana, for a TALIF research grant. Publisher Copyright: © the Owner Societies 2017.

PY - 2017

Y1 - 2017

N2 - The ABO3 perovskite lanthanum ferrite (LaFeO3) is a technologically important electrode material for nickel-metal hydride batteries, energy storage and catalysis. However, the electrochemical hydrogen adsorption mechanism on LaFeO3 surfaces remains under debate. In the present study, we have employed spin-polarized density functional theory calculations, with the Hubbard U correction (DFT+U), to unravel the adsorption mechanism of H2 on the LaFeO3(010) surface. We show from our calculated adsorption energies that the preferred site for H2 adsorption is the Fe-O bridge site, with an adsorption energy of -1.18 eV (including the zero point energy), which resulted in the formation of FeOH and FeH surface species. H2 adsorption at the surface oxygen resulted in the formation of a water molecule, which leaves the surface to create an oxygen vacancy. The H2 molecule is found to interact weakly with the Fe and La sites, where it is only physisorbed. The electronic structures of the surface-adsorption systems are discussed via projected density of state and Löwdin population analyses. The implications of the calculated adsorption strengths and structures are discussed in terms of the improved design of nickel-metal hydride (Ni-MH) battery prototypes based on LaFeO3.

AB - The ABO3 perovskite lanthanum ferrite (LaFeO3) is a technologically important electrode material for nickel-metal hydride batteries, energy storage and catalysis. However, the electrochemical hydrogen adsorption mechanism on LaFeO3 surfaces remains under debate. In the present study, we have employed spin-polarized density functional theory calculations, with the Hubbard U correction (DFT+U), to unravel the adsorption mechanism of H2 on the LaFeO3(010) surface. We show from our calculated adsorption energies that the preferred site for H2 adsorption is the Fe-O bridge site, with an adsorption energy of -1.18 eV (including the zero point energy), which resulted in the formation of FeOH and FeH surface species. H2 adsorption at the surface oxygen resulted in the formation of a water molecule, which leaves the surface to create an oxygen vacancy. The H2 molecule is found to interact weakly with the Fe and La sites, where it is only physisorbed. The electronic structures of the surface-adsorption systems are discussed via projected density of state and Löwdin population analyses. The implications of the calculated adsorption strengths and structures are discussed in terms of the improved design of nickel-metal hydride (Ni-MH) battery prototypes based on LaFeO3.

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A DFT+U investigation of hydrogen adsorption on the LaFeO₃(010) surface

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