Theoretical insights into the support effect on the NO activation over platinum-group metal catalysts

We systematically explored NO activation at metal/oxide interfaces by the combination of Sr3Ti2O7, Sr3Fe2O7, CeO2, anatase-TiO2, ZrO2, and ?-Al2O3 supports and the platinum-group metal cluster (Pd-4, Pt-4, and Rh-4) using slab-model density functional theory calculations. These metal clusters can be strongly adsorbed at these metal oxide surfaces. The Pt-4 and Rh-4 clusters show larger adsorption energies than the Pd-4 cluster, yet the ?-Al2O3(100) surface shows smaller adsorption energies than other metal oxide surfaces. One oxygen vacancy close to the metal cluster was constructed to evaluate the NO activation at those metal/oxide interfaces. The O atom of NO refills the oxygen vacancy after NO dissociation, while the N adatom is left on the metal cluster. The exothermic process was identified for the NO activation except for the Sr3Fe2O7 case, indicating the significant role of the interplay between the metal cluster and oxygen vacancy.

Automated summary

This study systematically explored the activation of NO at metal/oxide interfaces using various metal oxide supports and platinum-group metal clusters. The Pt-4 and Rh-4 clusters showed stronger adsorption energies than the Pd-4 cluster, with the α-Al2O3(100) surface showing the lowest adsorption energy. The activation of NO was found to be an exothermic process, except for the Sr3Fe2O7 case, highlighting the importance of the interplay between the metal cluster and oxygen vacancy.