Theoretical insights into the hydrophobicity of low index CeO 2 surfaces

Marco Fronzi, M. Hussein N. Assadi, Dorian A.H. Hanaor

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

The hydrophobicity of CeO 2 surfaces is examined here. Since wettability measurements are extremely sensitive to experimental conditions, we propose a general approach to obtain contact angles between water and ceria surfaces of specified orientations based on density functional calculations. In particular, we analysed the low index surfaces of this oxide to establish their interactions with water. According to our calculations, the CeO 2 (111) surface was the most hydrophobic with a contact angle of Θ = 112.53° followed by (100) with Θ = 93.91°. The CeO 2 (110) surface was, on the other hand, mildly hydrophilic with Θ = 64.09°. By combining our calculations with an atomistic thermodynamic approach, we found that the O terminated (100) surface was unstable unless fully covered by molecularly adsorbed water. We also identified a strong attractive interaction between the hydrogen atoms in water molecules and surface oxygen, which gives rise to the hydrophilic behaviour of (110) surfaces. Interestingly, the adsorption of water molecules on the lower-energy (111) surface stabilises oxygen vacancies, which are expected to enhance the catalytic activity of this plane. The findings here shed light on the origin of the intrinsic wettability of rare earth oxides in general and CeO 2 surfaces in particular and also explain why CeO 2 (100) surface properties are so critically dependant on applied synthesis methods.

Original languageEnglish
Pages (from-to)68-74
Number of pages7
JournalApplied Surface Science
Volume478
DOIs
Publication statusPublished - 2019 Jun 1
Externally publishedYes

Keywords

  • CeO surfaces
  • Contact angle
  • Density functional theory
  • GGA + U

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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