Activated dissociation of O2 on Pb(111) surfaces by Pb adatoms

TL;DR

This study uses first-principles calculations to show that Pb adatoms activate O2 dissociation on Pb(111) surfaces at room temperature, explaining observed two-step oxidation processes.

Contribution

It reveals the role of Pb adatoms in activating O2 dissociation on Pb(111), providing a theoretical explanation for two-step oxidation.

Findings

Pb adatoms enhance molecular O2 adsorption

O2 dissociates during room-temperature annealing with adatoms

Theory explains two-step oxidation process

Abstract

We investigate the dissociation of O2 on Pb(111) surface using first-principles calculations. It is found that in a practical high-vacuum environment, the adsorption of molecular O2 takes place on clean Pb surfaces only at low temperatures such as 100 K, but the O2 easily desorbs at (elevated) room temperatures. It is further found that the Pb adatoms enhance the molecular adsorption and activate the adsorbed O2 to dissociate during subsequent room-temperature annealing. Our theory explains the observation of a two-step oxidation process on the Pb surfaces by the unique role of Pb adatoms.