Overcoming activity/stability tradeoffs in CO oxidation catalysis by Pt/CeO2

The use of redox active metal oxides to support noble metals is critical in the design of highly-active CO oxidation catalysts for gas emissions control. Unfortunately, supports promoting the activity, such as CeO2, tend also to promote acute catalyst deactivation by turning highly-active metallic Pt clusters into less-active PtOx species, under practical reaction conditions (high-temperature and/or the excess of O2). This leads to a problematic activity/stability tradeoff where Pt/CeO2 catalysts, highly-active, and Pt on non-reducible supports, highly stable, are bookends. Herein, we report a method to trap Pt at V-shaped pockets/stepped sites of CeO2 that break this undesired correlation by showing both high activity and stability in the CO oxidation reaction. 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 (deactivating) re-oxidation paths of the metal, as a result of the high-energy required to form disordered/distorted PtOx ensembles at these positions. This new material allows, thus, to operate outside the commonly observed, limiting, activity/stability tradeoff. CO oxidation catalysts face a tradeoff between high activity and stability due to oxidation-induced deactivation. By trapping Pt clusters at stepped CeO2 pockets, this work circumvents the stability-activity dilemma.