Catalytic Reduction of Nitrous Oxide by the Low-Symmetry Pt8 Cluster

Abstract

The search for a catalyst for the reduction of nitrous oxide (N₂O) is now imperative, as this molecule is a very dangerous pollutant. We found that the low-symmetry Pt₈ cluster presents multiple reaction pathways for N₂O rupture, which are regioselective. This result was revealed by means of density functional theory calculations within the zero-order-regular approximation, ZORA, explicitly including relativistic effects. It is further proved that Pt₈ is a competitive N₂O catalyst compared to sub-nanometric rhodium clusters, obtaining similar reaction barriers. The hot adsorption site, a tip atom of Pt₈, and the rotation of the N₂O molecule over the metallic cluster promote the formation of a frustrated bridge activated transition state, Pt₈-N₂O. This transition structure yields to spontaneous dissociation of N₂O without bridge formation. Along this catalytic process, rearrangements within the metal cluster take place, preserving its stability. Moreover, in addition to being important attributes of the Pt₈ particle in the N₂O reduction, fluxionality and multiple reaction pathways may also prevent poisoning effects. Overall, this differs from reported results for more symmetric metal particles also used as catalysts.