Adsorption of ethane, ethene, and ethyne on reconstructed Fe3O4(001)

The adsorption of the C2 hydrocarbons, including ethane, ethene, and ethyne, are studied on magnetite Fe3O4(001) by a combination of molecular beam dosing, temperature programmed desorption, and X-ray photoelectron spectroscopy. The ethane desorption profile has a single temperature invariant peak at 100 K, while ethene and ethyne exhibit additional peaks at similar to 120 -and similar to 135 K. An inversion analysis is used to extract coverage-dependent desorption energies as well as coverage-averaged prefactors for each molecule. Ethene and ethyne exhibit moderate coverage-dependent desorption energies decreasing from similar to 80 to similar to 30 kJ/mol at saturation, while ethane shows a relatively coverage invariant desorption energy similar to 28 kJ/mol. The desorption energies of the C2 hydrocarbons increase in the order of increasing bond order. This is likely due to the enhanced interaction of the ethene and ethyne pi system to the coordinatively unsaturated octahedral Fe sites (Fe-oct) on the oxide surface. The saturation coverages of each C2 hydrocarbon at 82 K were also determined. These match well with the 2-dimensional area determined from their liquid densities.

Automated summary

The adsorption of C2 hydrocarbons on Fe3O4(001) was studied using various experimental methods, revealing different desorption characteristics for each molecule, with desorption energies increasing with bond order. The saturation coverage at 82K matches well with the 2-dimensional area determined from liquid densities.