Embedding Ultrafine and High‐Content Pt Nanoparticles at Ceria Surface for Enhanced Thermal Stability

Abstract

Ultrafine Pt nanoparticles loaded on ceria (CeO2) are promising nanostructured catalysts for many important reactions. However, such catalysts often suffer from thermal instability due to coarsening of Pt nanoparticles at elevated temperatures, especially for those with high Pt loading, which leads to severe deterioration of catalytic performances. Here, a facile strategy is developed to improve the thermal stability of ultrafine (1–2 nm)‐Pt/CeO2 catalysts with high Pt content (≈14 wt%) by partially embedding Pt nanoparticles at the surface of CeO2 through the redox reaction at the solid–solution interface. Ex situ heating studies demonstrate the significant increase in thermal stability of such embedded nanostructures compared to the conventional loaded catalysts. The microscopic pathways for interparticle coarsening of Pt embedded or loaded on CeO2 are further investigated by in situ electron microscopy at elevated temperatures. Their morphology and size evolution with heating temperature indicate that migration and coalescence of Pt nanoparticles are remarkably suppressed in the embedded structure up to about 450 °C, which may account for the improved thermal stability compared to the conventional loaded structure.

Probing the Origin of Photocatalytic Effects in Photothermochemical Dry Reforming of Methane on a Pt/CeO2 Catalyst

“…The Pt NPs with a size of around 2 nm and a typical interplanar lattice spacing of 0.23 nm, corresponding to the (111) facet, were deposited on CeO 2 (Figure e) and ZrO 2 (Figure S3e). The Pt particles on Pt/ZrO 2 are more obvious than those on Pt/CeO 2 from the TEM images, which could be due to partial encapsulation of the Pt nanoparticles by CeO 2 because of the stronger interaction between Pt and CeO 2 support. , …”

“…The Pt particles on Pt/ZrO 2 are more obvious than those on Pt/CeO 2 from the TEM images, which could be due to partial encapsulation of the Pt nanoparticles by CeO 2 because of the stronger interaction between Pt and CeO 2 support. 26,27 The structure of the catalysts was further investigated by Xray diffraction (XRD) (Figure S4). Pt diffraction peaks were not obvious for both samples, probably due to the low volume fraction.…”

Selective Etching of N‐Doped Graphene Meshes as Metal‐Free Catalyst with Tunable Kinetics, High Activity and the Origin of New Catalytic Behaviors

“…Catalysts are typically described in terms of an apparent reaction rate constant, k app , which is found to be proportional to the concentration of catalyst present in system. Therefore, we use k 1 , a normalized k app by catalyst concentration (defined as k 1 = k app /M, where M is the concentration of catalyst in the whole reaction solution), to exclude the influence of catalyst concentration on the reaction rate. Obviously, the five N‐RGO sheets exhibited excellent activity, comparable to metal nanoparticles, the 5‐NRGO meshes had a maximum k 1 of 1.0 s −1 g −1 L, which is 14‐fold higher than that of pore‐free N‐doped graphene, 26‐fold higher than surface‐modified RGO without dopant (see comparison in Table S2, Supporting Information) .…”

Controlled growth of ultrafine metal nanoparticles mediated by solid supports

“…Zhang et al developed a way of in-situ embedding Pt UMNPs (1-2 nm) into a nanorod-shaped cerium dioxide (CeO 2 ) through a redox reaction that occurs at the solid solution interface (Figure 13). 98 CeO 2 has extremely high oxygen storage performance and strong interactions with metals, therefore is often used as a support for MNPs. Pt-CeO 2 shows superior thermal stability and durability because of the strong Pt-O bonds formed between Pt UMNPs and O atoms in CeO 2 .…”