Unique role of silica in MOF-Derived High-Loading Palladium-on-Ceria single atom catalysts with excellent efficiency and durability.

It is a great challenge to develop a facile strategy to synthesize SACs with both high loading quantity and stability. Here, we report a silica-nanocasted method to not only prohibit structure collapsing of ceria supports during calcination process, but also facilitate the activation of oxygen species, consequently establishing strong metal-support interactions to stabilize and activate Pd single atoms. [Display omitted] • A facile strategy is devised to stabilize high-content Pd single-atom catalysts. • SiO 2 plays a vital role in stabilizing the structure against collapsing. • SiO 2 activates the surface oxygen by donating electrons to weaken Ce-O bond. • Strong metal-support interaction is achieved to stabilize and activate Pd atoms. • The promising catalytic activity and durability in CO oxidation can be achieved. In most cases, the sintering tendency of supported metal single atoms could be attributed to the unstable structural characteristics of supports in demanding operating conditions, particularly for high-loading single-atom catalysts (SACs), ultimately resulting in deactivation. To address this issue, SiO 2 is employed to enhance the structural stability of both supports and the supported Pd single atoms. SiO 2 serves not only to prevent the collapse of support structures but also to promote the activation of surface oxygen species by facilitating electron transfer with the supports. This, in turn, establishes strong metal-support interactions (MSIs) to stabilize and activate atomically dispersed Pd species. Additionally, the electrons donated from Ce-O and Si-O to Pd atoms further catalyze the formation of oxygen vacancies, ultimately leading to significantly improved activity and durability in CO oxidation. Without SiO 2 , the instability of support structure, coupled with the weak MSIs, promotes the aggregation of Pd atoms, resulting in relatively lower catalytic activity and durability. [ABSTRACT FROM AUTHOR]