TY - JOUR
T1 - Insights into the Characteristic Gap Level and n-Type Conductivity of Rutile TiO 2 from the Hybrid Functional Method
AU - Han, Xiaoping
AU - Amrane, Noureddine
AU - Zhang, Zongsheng
AU - Benkraouda, Maamar
N1 - Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/1/31
Y1 - 2019/1/31
N2 - Using the Heyd-Scyseria-Ernzerhof (HSE) hybrid functional in the framework of the density functional theory (DFT), we probe the insight into the characteristic gap level and n-type conductivity of the intrinsic rutile TiO 2 . Thermodynamic and kinetic investigations have been conducted to elaborate the favorability for the formation of the possible n-type defects and unintentional impurities in rutile TiO 2 . Results show that oxygen vacancy is clearly identified to induce a deep localized state inside the forbidden energy region through localizing two excess electrons at two Ti 4+ ions along the [001] direction and reducing them into Ti 3+ ions, accounting for the characteristic gap level observed experimentally. The e g orbital composition of this gap level offers an accountable explanation of the experimentally measured ferromagnetism in TiO 2-x , while the electron transition from this characteristic level is contributable to the photocatalytic behaviors and visible photoluminescence of slightly reduced TiO 2 . Also, unintentional incorporation of hydrogen substitution for oxygen acts as a shallow donor, providing a consistent explanation of the n-type conductivity in TiO 2 . The fundamental understanding of these characteristic properties and the associated functionalities would be essential to improving and expanding the practical applications of TiO 2 -based materials and devices.
AB - Using the Heyd-Scyseria-Ernzerhof (HSE) hybrid functional in the framework of the density functional theory (DFT), we probe the insight into the characteristic gap level and n-type conductivity of the intrinsic rutile TiO 2 . Thermodynamic and kinetic investigations have been conducted to elaborate the favorability for the formation of the possible n-type defects and unintentional impurities in rutile TiO 2 . Results show that oxygen vacancy is clearly identified to induce a deep localized state inside the forbidden energy region through localizing two excess electrons at two Ti 4+ ions along the [001] direction and reducing them into Ti 3+ ions, accounting for the characteristic gap level observed experimentally. The e g orbital composition of this gap level offers an accountable explanation of the experimentally measured ferromagnetism in TiO 2-x , while the electron transition from this characteristic level is contributable to the photocatalytic behaviors and visible photoluminescence of slightly reduced TiO 2 . Also, unintentional incorporation of hydrogen substitution for oxygen acts as a shallow donor, providing a consistent explanation of the n-type conductivity in TiO 2 . The fundamental understanding of these characteristic properties and the associated functionalities would be essential to improving and expanding the practical applications of TiO 2 -based materials and devices.
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U2 - 10.1021/acs.jpcc.8b09766
DO - 10.1021/acs.jpcc.8b09766
M3 - Article
AN - SCOPUS:85060299737
SN - 1932-7447
VL - 123
SP - 2037
EP - 2047
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 4
ER -