CO Oxidation at SnO2/Pt3Sn(111) Interfaces

Segregation induced formation of oxide/metal interfaces can significantly influence the catalytic activity of alloy nanoparticles. One example is Pt3Sn nanoparticles, which are known to segregate into SnOX and an Sn deficient alloy phase during typical operating conditions for CO oxidation. Here, we use density functional theory calculations to investigate CO oxidation over Pt3Sn(111) supported SnO2 and (SnO2)3, representing the initial state of segregation. The results are compared to CO oxidation at an interface between bulk-like SnO2 and Pt3Sn(111). The barrier for CO oxidation via a Mars–van Krevelen mechanism is found to be lower on SnO2 and (SnO2)3 as compared to the bulk-like model. However, the regeneration of the finite systems is associated with higher barriers for O2 dissociation which may become the rate limiting step in the low temperature regime where the metal surface can be assumed to be CO covered.