Adsorption of V on a hematite (0 0 0 1) surface and its oxidation: Submonolayer coverage

Jianjian Jin, Xiaoyan Ma, C. Y. Kim, D. E. Ellis*, M. J. Bedzyk

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

The adsorption of submonolayer V on an idealized model hematite (0 0 0 1) surface and subsequent oxidation under atomic O adsorption are studied by density functional theory. The preferred adsorption sites, adsorption energy and configuration changes due to V and O adsorption are investigated. It is found that in most cases V forms threefold bonds with surface O atoms, inducing a large geometry change at the hematite surface and near surface region and a bond stretch between surface Fe and O. The adsorption energy is mainly decided by interplay between adsorbed metal-surface oxygen bonding and adsorbed metal - subsurface metal interaction. The relative energy of subsequent O adsorption and geometry depends on the reformed V/hematite structure. Electronic properties such as projected densities of states and chemical state change upon V adsorption are studied through both periodic slab and embedded cluster localized orbital calculations; both strong vanadium-oxygen and vanadium-iron interactions are found. While V generally donates electrons to a hematite surface, causing nearby Fe to be partially reduced, the Fe and V oxidization state depends very much on the coverage and detailed adsorption configuration. When the V/hematite system is exposed to atomic O, V is further oxidized and surface/near surface Fe is re-oxidized. Our theoretical results are compared with X-ray surface standing wave and X-ray photoelectron spectroscopic measurements. The influence of d-electron correlation on the predicted structures is briefly discussed, making use of the DFT + U scheme.

Original languageEnglish (US)
Pages (from-to)3082-3098
Number of pages17
JournalSurface Science
Volume601
Issue number14
DOIs
StatePublished - Jul 15 2007

Funding

This research was supported by the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, US Department of Energy, Grant No. DE-FG02-03ER15457. The work of J.J. Jin was supported by the MRSEC Program of the National Science Foundation (DMR-0076097) through the Materials Research Center of Northwestern University.

Keywords

  • Density functional theory
  • Hematite
  • Surface oxidation
  • Vanadium adsorption

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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