A Multi-Technique Study of $C{O}_2$ Adsorption on $F{e}_3$$O_4$ Magnetite

Abstract

The adsorption of $C{O}_2$ on the $F{e}_3$$O_4$(001)-($\sqrt{2}$ $\times$ $\sqrt{2}$)R45° surface was studied experimentally using temperature programmed desorption (TPD), electron spectroscopies (UPS and XPS), and scanning tunneling microscopy (STM). $C{O}_2$ binds most strongly at defects related to Fe2+ including antiphase domain boundaries in the surface reconstruction and above incorporated Fe interstitials. On the pristine surface, $C{O}_2$ adsorbs molecularly at fivefold-coordinated Fe3+ sites with a binding energy of 0.4 eV. Above a coverage of 4 molecules per ($\sqrt{2}$ $\times$ $\sqrt{2}$)R45° unit cell, further adsorption results in a compression of the first monolayer up to a density approaching that of a $C{O}_2$ ice layer. Surprisingly, desorption of the second monolayer occurs at a lower temperature ($\approx$ 84 K) than $C{O}_2$ multilayers ($\approx$ 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.

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Cited by in corpus (10)

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• Water Agglomerates on Fe3O4(001)
• CO oxidation by Pt2/Fe3O4: metastable dimer and support configurations facilitate lattice oxygen extraction
• Cluster Catalysis with Lattice Oxygen: Tracing Oxygen Transport from a Magnetite(001) Support onto Small Pt Clusters
• Water Structures Reveal Local Hydrophobicity on the In2O3(111) Surface
• Adsorption of CO on the Fe3O4(001) Surface
• Rapid oxygen exchange between hematite and water vapor
• Oxygen-Terminated (1x1) Reconstruction of Reduced Magnetite Fe${}_3$O${}_4$(111)
• Infrared Reflection Absorption Spectroscopy Setup with Incidence Angle Selection for Surfaces of Non-Metals
• A Multi-Technique Study of C2H4 Adsorption on a Model Single-Atom Rh1 Catalyst