(409c) Overcoming Tradeoffs in Oxidation Catalysis

In this work, we discuss recent advances in the design of dispersed supported metal species to overcome inconvenient tradeoffs in catalysis. This is illustrated through a simple reaction, the CO oxidation reaction, catalyzed by Pt on reducible and non-reducible supports. Our data shows that metallic Pt nanoparticles are more active compared to single Pt atoms, and oxidic PtO_x clusters, and that the catalysis is most effective when the reduced Pt species are deposited on redox active supports, such as CeO₂, as reported by others. Unfortunately, promotion of the Pt activity via cooperation with the CeO₂ is accompanied by an acute deactivation of the Pt under practical reaction conditions (i.e. high-temperature and/or the excess of O₂), through a process that turns highly-active metallic Pt clusters into less-active PtO_x species. This situation results in the typical activity/stability conundrum reported in the literature, where Pt/CeO₂ and Pt on non-reducible supports are bookends (one highly active, but unstable, and vice versa).

Herein, we report Pt/CeO₂ catalysts that operate outside this undesired activity/stability correlation. More specifically, these materials are ~3-times more active than state-of-the-art Pt/CeO₂ catalysts under steady reaction conditions, and ~40-times more active than best Pt@zeolite catalysts reported so far. XAS, CO-DRIFT, XPS, HAADF-STEM, and DFT are used to infer that the generation of low order metallic Pt clusters connected to two crystallographic planes of the support is key to inhibit re-oxidation paths associated with the catalyst deactivation, without losing effective cooperation for the catalysis at the metal/support interface.