Phase Quantification of Heterogeneous Surfaces Using DFT-Simulated Valence Band Photoemission Spectra

Roxy Lee; Raul Quesada-Cabrera; Joe Willis; Asif Iqbal; Ivan P. Parkin; David O. Scanlon; R. G. Palgrave

doi:10.1021/acsami.3c06638

Phase Quantification of Heterogeneous Surfaces Using DFT-Simulated Valence Band Photoemission Spectra

Roxy Lee, Raul Quesada-Cabrera^*, Joe Willis, Asif Iqbal, Ivan P. Parkin, David O. Scanlon, R. G. Palgrave^*

^*Corresponding author for this work

Chemistry

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Abstract

Quantifying the crystallographic phases present at a surface is an important challenge in fields such as functional materials and surface science. X-ray photoelectron spectroscopy (XPS) is routinely employed in surface characterization to identify and quantify chemical species through core line analysis. Valence band (VB) spectra contain characteristic but complex features that provide information on the electronic density of states (DoS) and thus can be understood theoretically using density functional theory (DFT). Here, we present a method of fitting experimental photoemission spectra with DFT models for quantitative analysis of heterogeneous systems, specifically mapping the anatase to rutile ratio across the surface of mixed-phase TiO2 thin films. The results were correlated with mapped photocatalytic activity measured using a resazurin-based smart ink. This method allows large-scale functional and surface composition mapping in heterogeneous systems and demonstrates the unique insights gained from DFT-simulated spectra on the electronic structure origins of complex VB spectral features.

Original language	English
Pages (from-to)	39956–39965
Number of pages	10
Journal	ACS Applied Materials & Interfaces
Volume	15
Issue number	33
Early online date	8 Aug 2023
DOIs	https://doi.org/10.1021/acsami.3c06638
Publication status	Published - 23 Aug 2023

Bibliographical note

Acknowledgments:
R.L. acknowledges funding from the M3S CDT (EP/L015862/1) and sponsorship by Thermo Fisher Scientific. The X-ray photoelectron (XPS) data collection was performed at the EPSRC National Facility for XPS (“HarwellXPS”), operated by Cardiff University and UCL, under Contract No. PR16195. RQC thanks the Beatriz Galindo Program (MEFP) and the Canarian Government (FEDER, ACIISI ProID2021010047), in Spain. The authors acknowledge the use of the UCL Myriad, Kathleen, and Thomas High Performance Computing Facilities (Myriad@UCL, Kathleen@UCL, Thomas@UCL), and associated support services, in the completion of this work.

Keywords

crystallographic phases
density functional theory
anatase to rutile ratio

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LeeR2022PhaseFinal published version, 5.2 MBLicence: Creative Commons: Attribution (CC BY)

Cite this

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title = "Phase Quantification of Heterogeneous Surfaces Using DFT-Simulated Valence Band Photoemission Spectra",

abstract = "Quantifying the crystallographic phases present at a surface is an important challenge in fields such as functional materials and surface science. X-ray photoelectron spectroscopy (XPS) is routinely employed in surface characterization to identify and quantify chemical species through core line analysis. Valence band (VB) spectra contain characteristic but complex features that provide information on the electronic density of states (DoS) and thus can be understood theoretically using density functional theory (DFT). Here, we present a method of fitting experimental photoemission spectra with DFT models for quantitative analysis of heterogeneous systems, specifically mapping the anatase to rutile ratio across the surface of mixed-phase TiO2 thin films. The results were correlated with mapped photocatalytic activity measured using a resazurin-based smart ink. This method allows large-scale functional and surface composition mapping in heterogeneous systems and demonstrates the unique insights gained from DFT-simulated spectra on the electronic structure origins of complex VB spectral features.",

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note = "Acknowledgments: R.L. acknowledges funding from the M3S CDT (EP/L015862/1) and sponsorship by Thermo Fisher Scientific. The X-ray photoelectron (XPS) data collection was performed at the EPSRC National Facility for XPS (“HarwellXPS”), operated by Cardiff University and UCL, under Contract No. PR16195. RQC thanks the Beatriz Galindo Program (MEFP) and the Canarian Government (FEDER, ACIISI ProID2021010047), in Spain. The authors acknowledge the use of the UCL Myriad, Kathleen, and Thomas High Performance Computing Facilities (Myriad@UCL, Kathleen@UCL, Thomas@UCL), and associated support services, in the completion of this work.",

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AU - Iqbal, Asif

AU - Parkin, Ivan P.

AU - Scanlon, David O.

AU - Palgrave, R. G.

N1 - Acknowledgments: R.L. acknowledges funding from the M3S CDT (EP/L015862/1) and sponsorship by Thermo Fisher Scientific. The X-ray photoelectron (XPS) data collection was performed at the EPSRC National Facility for XPS (“HarwellXPS”), operated by Cardiff University and UCL, under Contract No. PR16195. RQC thanks the Beatriz Galindo Program (MEFP) and the Canarian Government (FEDER, ACIISI ProID2021010047), in Spain. The authors acknowledge the use of the UCL Myriad, Kathleen, and Thomas High Performance Computing Facilities (Myriad@UCL, Kathleen@UCL, Thomas@UCL), and associated support services, in the completion of this work.

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N2 - Quantifying the crystallographic phases present at a surface is an important challenge in fields such as functional materials and surface science. X-ray photoelectron spectroscopy (XPS) is routinely employed in surface characterization to identify and quantify chemical species through core line analysis. Valence band (VB) spectra contain characteristic but complex features that provide information on the electronic density of states (DoS) and thus can be understood theoretically using density functional theory (DFT). Here, we present a method of fitting experimental photoemission spectra with DFT models for quantitative analysis of heterogeneous systems, specifically mapping the anatase to rutile ratio across the surface of mixed-phase TiO2 thin films. The results were correlated with mapped photocatalytic activity measured using a resazurin-based smart ink. This method allows large-scale functional and surface composition mapping in heterogeneous systems and demonstrates the unique insights gained from DFT-simulated spectra on the electronic structure origins of complex VB spectral features.

AB - Quantifying the crystallographic phases present at a surface is an important challenge in fields such as functional materials and surface science. X-ray photoelectron spectroscopy (XPS) is routinely employed in surface characterization to identify and quantify chemical species through core line analysis. Valence band (VB) spectra contain characteristic but complex features that provide information on the electronic density of states (DoS) and thus can be understood theoretically using density functional theory (DFT). Here, we present a method of fitting experimental photoemission spectra with DFT models for quantitative analysis of heterogeneous systems, specifically mapping the anatase to rutile ratio across the surface of mixed-phase TiO2 thin films. The results were correlated with mapped photocatalytic activity measured using a resazurin-based smart ink. This method allows large-scale functional and surface composition mapping in heterogeneous systems and demonstrates the unique insights gained from DFT-simulated spectra on the electronic structure origins of complex VB spectral features.

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JO - ACS Applied Materials & Interfaces

JF - ACS Applied Materials & Interfaces

IS - 33

ER -

Phase Quantification of Heterogeneous Surfaces Using DFT-Simulated Valence Band Photoemission Spectra

Abstract

Bibliographical note

Keywords

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