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

Abstract

The search for a catalyst for the reduction of nitrous oxide (N 2 O) is now imperative, as this molecule is a very dangerous pollutant. We found that the low-symmetry Pt 8 cluster presents multiple reaction pathways for N 2 O 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 Pt 8 is a competitive N 2 O catalyst compared to sub-nanometric rhodium clusters, obtaining similar reaction barriers. The hot adsorption site, a tip atom of Pt 8, and the rotation of the N 2 O molecule over the metallic cluster promote the formation of a frustrated bridge activated transition state, Pt 8 –N 2 O. This transition structure yields to spontaneous dissociation of N 2 O 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 Pt 8 particle in the N 2 O 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.