Keys Unlocking Redispersion of Reactive PdOx Nanoclusters on Ce-Functionalized Perovskite Oxides for Methane Activation

Nowadays, trace CH4 emitted from vehicle exhausts severely threaten the balance of the ecology system of our earth. Thereby, the development of active and stable catalysts capable of methane conversion under mild conditions is critical. Here, we present a convenient method to redisperse catalytically inert PdO nanoparticles (NPs) (>10 nm) into reactive PdOx nanoclusters (similar to 2 nm) anchored on a Ce-doped LaFeO3 parent. Isothermally activated in an N-2 flow, the redispersed catalyst achieved a CH4 conversion of 90% at 400 degrees C, which is significantly higher than the fresh and H-2- and O-2-treated counterparts (625, 616, and 641 degrees C, respectively), indicating the importance of the gas atmosphere in the redispersion of PdO NPs. In addition, the comprehensive catalyst characterizations demonstrated that the isolated Ce ions in the perovskite lattice play an irreplaceable role in the redispersion of reactive sites and the reduction of the energy barrier for C-H scission. More importantly, the Ce additive helps to stabilize the PdOx species by reducing overoxidation, resulting in significant lifetime extension. Through a thorough understanding of structural manipulation, this study sheds light on the design of highly performing supported catalysts for methane oxidation.

Automated summary

This study presents a convenient method of redispersing catalytically inert PdO nanoparticles into reactive PdOx nanoclusters anchored on a Ce-doped LaFeO3 parent. It is found that the gas atmosphere plays a crucial role in the redispersion of PdO nanoparticles, and the presence of Ce ions helps stabilize the PdOx species and extend the catalyst's lifetime. This study provides valuable insights for the design of highly performing supported catalysts for methane oxidation.