Origin of the enhanced visible-light absorption in N-doped bulk anatase TiO2 from first-principles calculations

M. Harb; P. Sautet; P. Raybaud

doi:10.1021/jp204059q

Origin of the enhanced visible-light absorption in N-doped bulk anatase TiO₂ from first-principles calculations

M. Harb, P. Sautet, P. Raybaud^*

^*Corresponding author for this work

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

92 Scopus citations

Abstract

Extension of the absorption properties of TiO₂ photocatalytic materials to the visible part of the solar spectrum is of major importance for energy and cleaning up applications. We carry out a systematic study of the N-doped anatase TiO₂ material using spin-polarized density functional theory (DFT) and the range-separated hybrid HSE06 functional. The thermodynamic stability of competitive N-doped TiO₂ structural configurations is studied as a function of the oxygen chemical potential and of various chemical doping agents: N₂, (N₂ + H₂), NH₃, N₂H₄. We show that the diamagnetic TiO _(2-3x)N_2x system corresponding to a separated substitutional N species (with 2-4% N impurities) and formation of one-half concentration of O vacancies (1-2 atom %) is an optimal configuration thermodynamically favored by NH₃, N₂H₄, and (N₂ + H₂) chemical doping agents presenting a dual nitrating-reducing character. The simulated UV-vis absorption spectra using the perturbation theory (DFPT) approach demonstrates unambiguously that the diamagnetic TiO_(2-3x)N_2x system exhibits the enhanced optical absorption in N-doped TiO₂ under visible-light irradiation. Electronic analysis further reveals a band gap narrowing of 0.6 eV induced by delocalized impurity states located at the top of the valence band of TiO ₂. A fruitful comparison with experimental data is furnished.

Original language	English (US)
Pages (from-to)	19394-19404
Number of pages	11
Journal	JOURNAL OF PHYSICAL CHEMISTRY C
Volume	115
Issue number	39
DOIs	https://doi.org/10.1021/jp204059q
State	Published - Oct 6 2011

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): UK-C0017
Acknowledgements: This work was supported by Award No. UK-C0017, made by King Abdullah University of Science and Technology (KAUST). The authors thank E. Puzenat (IRCELYON) for fruitful discussion.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
General Energy
Surfaces, Coatings and Films
Physical and Theoretical Chemistry

Access to Document

10.1021/jp204059q

Cite this

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title = "Origin of the enhanced visible-light absorption in N-doped bulk anatase TiO2 from first-principles calculations",

abstract = "Extension of the absorption properties of TiO2 photocatalytic materials to the visible part of the solar spectrum is of major importance for energy and cleaning up applications. We carry out a systematic study of the N-doped anatase TiO2 material using spin-polarized density functional theory (DFT) and the range-separated hybrid HSE06 functional. The thermodynamic stability of competitive N-doped TiO2 structural configurations is studied as a function of the oxygen chemical potential and of various chemical doping agents: N2, (N2 + H2), NH3, N2H4. We show that the diamagnetic TiO (2-3x)N2x system corresponding to a separated substitutional N species (with 2-4% N impurities) and formation of one-half concentration of O vacancies (1-2 atom %) is an optimal configuration thermodynamically favored by NH3, N2H4, and (N2 + H2) chemical doping agents presenting a dual nitrating-reducing character. The simulated UV-vis absorption spectra using the perturbation theory (DFPT) approach demonstrates unambiguously that the diamagnetic TiO(2-3x)N2x system exhibits the enhanced optical absorption in N-doped TiO2 under visible-light irradiation. Electronic analysis further reveals a band gap narrowing of 0.6 eV induced by delocalized impurity states located at the top of the valence band of TiO 2. A fruitful comparison with experimental data is furnished.",

author = "M. Harb and P. Sautet and P. Raybaud",

note = "KAUST Repository Item: Exported on 2020-10-01 Acknowledged KAUST grant number(s): UK-C0017 Acknowledgements: This work was supported by Award No. UK-C0017, made by King Abdullah University of Science and Technology (KAUST). The authors thank E. Puzenat (IRCELYON) for fruitful discussion. This publication acknowledges KAUST support, but has no KAUST affiliated authors.",

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N1 - KAUST Repository Item: Exported on 2020-10-01 Acknowledged KAUST grant number(s): UK-C0017 Acknowledgements: This work was supported by Award No. UK-C0017, made by King Abdullah University of Science and Technology (KAUST). The authors thank E. Puzenat (IRCELYON) for fruitful discussion. This publication acknowledges KAUST support, but has no KAUST affiliated authors.

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N2 - Extension of the absorption properties of TiO2 photocatalytic materials to the visible part of the solar spectrum is of major importance for energy and cleaning up applications. We carry out a systematic study of the N-doped anatase TiO2 material using spin-polarized density functional theory (DFT) and the range-separated hybrid HSE06 functional. The thermodynamic stability of competitive N-doped TiO2 structural configurations is studied as a function of the oxygen chemical potential and of various chemical doping agents: N2, (N2 + H2), NH3, N2H4. We show that the diamagnetic TiO (2-3x)N2x system corresponding to a separated substitutional N species (with 2-4% N impurities) and formation of one-half concentration of O vacancies (1-2 atom %) is an optimal configuration thermodynamically favored by NH3, N2H4, and (N2 + H2) chemical doping agents presenting a dual nitrating-reducing character. The simulated UV-vis absorption spectra using the perturbation theory (DFPT) approach demonstrates unambiguously that the diamagnetic TiO(2-3x)N2x system exhibits the enhanced optical absorption in N-doped TiO2 under visible-light irradiation. Electronic analysis further reveals a band gap narrowing of 0.6 eV induced by delocalized impurity states located at the top of the valence band of TiO 2. A fruitful comparison with experimental data is furnished.

AB - Extension of the absorption properties of TiO2 photocatalytic materials to the visible part of the solar spectrum is of major importance for energy and cleaning up applications. We carry out a systematic study of the N-doped anatase TiO2 material using spin-polarized density functional theory (DFT) and the range-separated hybrid HSE06 functional. The thermodynamic stability of competitive N-doped TiO2 structural configurations is studied as a function of the oxygen chemical potential and of various chemical doping agents: N2, (N2 + H2), NH3, N2H4. We show that the diamagnetic TiO (2-3x)N2x system corresponding to a separated substitutional N species (with 2-4% N impurities) and formation of one-half concentration of O vacancies (1-2 atom %) is an optimal configuration thermodynamically favored by NH3, N2H4, and (N2 + H2) chemical doping agents presenting a dual nitrating-reducing character. The simulated UV-vis absorption spectra using the perturbation theory (DFPT) approach demonstrates unambiguously that the diamagnetic TiO(2-3x)N2x system exhibits the enhanced optical absorption in N-doped TiO2 under visible-light irradiation. Electronic analysis further reveals a band gap narrowing of 0.6 eV induced by delocalized impurity states located at the top of the valence band of TiO 2. A fruitful comparison with experimental data is furnished.

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