Atmosphere-dependent stability, mobility and CO oxidation performance of Pt single atoms and clusters on γ-alumina
Résumé
In this work, the stability of γ-alumina-supported single Pt atoms formed by oxidative treatment of an impregnated Pt precursor has been monitored by operando X-ray absorption spectroscopy (XAS). Their destabilization into subnanometric clusters under reductive treatment has been studied by XAS and environmental scanning transmission electron microscopy (E-STEM). DFT calculations allow us to fully rationalize these behaviors in terms of nuclearity and adsorbate coverage (O or H), which governs the cluster size, shape and interaction with the support.
Pt/γ-Al2O3 SACs were also submitted to CO oxidation heating/cooling cycles separated by a reduction treatment and the catalysts were analyzed by operando DRIFTS, operando XAS and STEM.