Temperature and Reaction Environment Influence the Nature of Platinum Species Supported on Ceria

Catalytic systems based on supported noble metals are extensively studied because of their widespread application. Discussions remain about the nature of the active species, whether they are atomically dispersed or nanoparticles, and their reactivity. In this work, combining in situ/operando spectroscopy with theoretical modeling, we propose a phase diagram of atomically dispersed platinum on ceria, demonstrating that it reversibly changes from (PtO2)-O-IV to (PtO)-O-II as a function of temperature and oxygen partial pressure. The phase diagram helps identify the stability domain of each species, while spectroscopies provide a quantitative evaluation depending on the reaction conditions. Finally, our results show that high-temperature activation in the presence of steam of supported atomically dispersed platinum enhances the activity toward low-temperature carbon monoxide oxidation because it promotes aggregation into nanoparticles. This work highlights the structure-activity relationship in supported metal catalysts and proposes a suitable approach to determine the amount of each species before the investigation of the reaction mechanism.

Automated summary

The study combines spectroscopy and theoretical modeling to propose a phase diagram of atomically dispersed platinum on ceria, revealing the structural changes of platinum under different temperatures and oxygen partial pressures. The results show that high-temperature activation promotes the aggregation of supported atomically dispersed platinum into nanoparticles, enhancing the activity towards low-temperature carbon monoxide oxidation. This work emphasizes the structure-activity relationship in supported metal catalysts and suggests a suitable method to determine the quantity of each species before investigating the reaction mechanism.