Quantum oscillations in adsorption energetics of atomic oxygen on Pb(111) ultrathin films: A density-functional theory study

TL;DR

This study uses density-functional theory to reveal how quantum size effects in ultrathin Pb(111) films influence oxygen adsorption energies, diffusion barriers, and work function oscillations, highlighting their role in surface oxidation processes.

Contribution

It provides the first systematic analysis of quantum oscillations in oxygen adsorption and diffusion on ultrathin Pb(111) films using first-principles calculations.

Findings

Adsorption energies exhibit bilayer oscillations.

Work function increases with oxygen adsorption but maintains bilayer oscillation.

Diffusion and penetration barriers oscillate with bilayer periodicity.

Abstract

Using first-principles calculations, we have systematically studied the quantum size effects of ultrathin Pb(111) films on the adsorption energies and diffusion energy barriers of oxygen atoms. For the on-surface adsorption of oxygen atoms at different coverages, all the adsorption energies are found to show bilayer oscillation behaviors. It is also found that the work function of Pb(111) films still keeps the bilayer-oscillation behavior after the adsorption of oxygen atoms, with the values being enlarged by 2.10 to 2.62 eV. For the diffusion and penetration of the adsorbed oxygen atoms, it is found that the most energetically favored paths are the same on different Pb(111) films. And because of the modulation of quantum size effects, the corresponding energy barriers are all oscillating with a bilayer period on different Pb(111) films. Our studies indicate that the quantum size effect in ultrathin metal films can modulate a lot of processes during surface oxidation.