A multi-technique study of CO2 adsorption on Fe3O4 magnetite

作者：Pavelec Jiri; Hulva Jan; Halwidl Daniel; Bliem Roland; Gamba Oscar; Jakub Zdenek; Brunbauer Florian; Schmid Michael; Diebold Ulrike; Parkinson Gareth S

来源：Journal of Chemical Physics, 2017, 146(1): 014701.

DOI：10.1063/1.4973241

<jats:p>The adsorption of CO2 on the Fe3O4(001)-(2 × 2)R45° surface was studied experimentally using temperature programmed desorption (TPD), photoelectron spectroscopies (UPS and XPS), and scanning tunneling microscopy. CO2 binds most strongly at defects related to Fe2+, including antiphase domain boundaries in the surface reconstruction and above incorporated Fe interstitials. At higher coverages,CO2 adsorbs at fivefold-coordinated Fe3+ sites with a binding energy of 0.4 eV. Above a coverage of 4 molecules per (2 × 2)R45° unit cell, further adsorption results in a compression of the first monolayer up to a density approaching that of a CO2 ice layer. Surprisingly, desorption of the second monolayer occurs at a lower temperature (≈84 K) than CO2 multilayers (≈88 K), suggestive of a metastable phase or diffusion-limited island growth. The paper also discusses design considerations for a vacuum system optimized to study the surface chemistry of metal oxide single crystals, including the calibration and characterisation of a molecular beam source for quantitative TPD measurements.</jats:p>

• 出版日期2017-1-7