Thermodynamically and Kinetically Stabilized Pt Clusters Against Sintering on CeO₂ Nanofibers Through Enclosing CeO₂...

Sintering is a major concern for the deactivation of supported metals catalysts, which is driven by the force of decreasing the total surface energy of the entire catalytic system. In this work, a double-confinement strategy is demonstrated to stabilize 2.6 nm-Pt clusters against sintering on electrospun CeO₂ nanofibers decorated by CeO₂ nanocubes (m-CeO₂ ). Thermodynamically, with the aid of CeO₂ -nanocubes, the intrinsically irregular surface of polycrystalline CeO₂ nanofibers becomes smooth, offering adjacent Pt clusters with decreased chemical potential differences on a relatively uniform surface. Kinetically, the Pt clusters are physically restricted on each facet of CeO₂ nanocubes in a nanosized region. In situ high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) observation reveals that the Pt clusters can be stabilized up to 800 °C even in a high density, which is far beyond their Tammann temperature, without observable size growth or migration. Such a sinter-resistant catalytic system is endowed with boosted catalytic activity toward both the hydrogenation of p-nitrophenol after being aged at 500 °C and the sinter-promoting exothermic oxidation reactions (e.g., soot oxidation) at high temperatures over 700 °C. This work offers new opportunities for exploring sinter-resistant nanocatalysts, starting from the rational design of whole catalytic system in terms of thermodynamic and kinetic aspects.