Scanning tunneling microscopy evidence for the Mars-van Krevelen type mechanism of low temperature CO oxidation on an FeO(1 1 1) film on Pt(1 1 1)

We provide experimental evidence that the low temperature CO oxidation reaction on an ultrathin FeO(1 1 1) film on Pt(1 1 1) proceeds through the Mars-van Krevelen type mechanism which includes the following steps: the FeO film is oxidized into an FeO2−x film with trilayer O–Fe–O structure; CO reacts with the weakly bound, topmost oxygen atoms, effectively reducing the FeO2−x surface to FeO-like; and the subsequent oxidation by O2 recovers the FeO2−x structure.