Fermi level dependence of gas-solid oxygen defect exchange mechanism on TiO2 (110) by first-principles calculations

Research output: Contribution to journalArticle

Abstract

In the same way that gases interact with oxide semiconductor surfaces from above, point defects interact from below. Previous experiments have described defect-surface reactions for TiO2(110), but an atomistic picture of the mechanism remains unknown. The present work employs computations by density functional theory of the thermodynamic stabilities of metastable states to elucidate possible reaction pathways for oxygen interstitial atoms at TiO2(110). The simulations uncover unexpected metastable states including dumbbell and split configurations in the surface plane that resemble analogous interstitial species in the deep bulk. Comparison of the energy landscapes involving neutral (unionized) and charged intermediates shows that the Fermi energy EF exerts a strong influence on the identity of the most likely pathway. The largest elementary-step thermodynamic barrier for interstitial injection trends mostly downward by 2.1 eV as EF increases between the valence and conduction band edges, while that for annihilation trends upward by 2.1 eV. Several charged intermediates become stabilized for most values of EF upon receiving conduction band electrons from TiO2, and the behavior of these species governs much of the overall energy landscape.

Original languageEnglish (US)
Pages (from-to)124710
JournalThe Journal of Chemical Physics
Volume153
Issue number12
DOIs
StatePublished - Sep 28 2020

Fingerprint Dive into the research topics of 'Fermi level dependence of gas-solid oxygen defect exchange mechanism on TiO2 (110) by first-principles calculations'. Together they form a unique fingerprint.

  • Cite this