Overcoming activity/stability tradeoffs in CO oxidation catalysis by Pt/CeO2
Benjamin Bohigues, Sergio Rojas‐Buzo, Davide Salusso, Yu Xia, Avelino Corma, Silvia Bordiga, Mercedes Boronat, Tom Willhammar, Manuel Moliner, Pedro Serna
Abstract
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.