Ultrasound-mediated synthesis of nanoporous fluorite-structured high-entropy oxides toward noble metal stabilization

High-entropy oxides (HEOs) are an emerging class of advanced ceramic materials capable of stabilizing ultrasmall nanoparticle catalysts. However, their fabrication still relies on high-temperature thermal treatment methodologies affording nonporous architectures. Herein, we report a facile synthesis of single-phase, fluorite-structured HEO nanocrystals via an ultrasound-mediated co-precipitation strategy under ambient conditions. Within 15 min of ultrasound exposure, high-quality fluorite-structured HEO (CeHfZrSnErOx) was generated as ultrasmallsized particles with high surface area and high oxygen vacancy concentration. Taking advantage of these unique structural features, palladium was introduced and stabilized in the form of highly dispersed Pd nanoclusters within the CeHfZrSnErOx architecture. Neither phase segregation of the CeHfZrSnErOx support nor Pd sintering was observed under thermal treatment up to 900 degrees C. The as-afforded Pd/CeHfZrSnErOx catalyst exhibits good catalytic performance toward CO oxidation, outperforming Pd/CeO2 of the same Pd loading, which highlights the inherent advantage of CeHfZrSnErOx as carrier support over traditional oxides.

Automated summary

In this study, a facile synthesis method for single-phase high-entropy oxide nanocrystals was reported, and palladium nanoclusters were successfully stabilized within the structure. The resulting catalyst showed good catalytic performance in CO oxidation, highlighting the advantage of the high-entropy oxide as a carrier support over traditional oxides.