Tuning Nanostructure of Flame-Made Palladium Deposited on Cerium Oxide: Unveiling Palladium Loading–Activity Relationships in Suzuki–Miyaura Cross-Coupling

High Resolution Image Download MS PowerPoint Slide Developing robust and recyclable heterogeneous catalysts for the Suzuki–Miyaura cross-coupling (SMC) reaction is crucial for improving operational efficiency and catalyst recovery in chemical synthesis. Herein, we address this challenge through the nanoscale engineering of palladium/ceria (Pd/CeO 2 ) catalysts prepared via a single-step flame spray pyrolysis (FSP) approach. A series of catalysts with systematically varied Pd loadings (0.1–50 wt %) were prepared to unravel the relationship between their physicochemical properties and catalytic performance. Comprehensive characterization and catalytic evaluation revealed a volcano-type dependence of activity on Pd loading, with the 5 wt % Pd/CeO 2 ( 5Pd/CeO 2 ) catalyst exhibiting the highest catalytic performance in mild conditions (97% yield, turnover number = 19.4). This superior activity was attributed to highly dispersed interfacial Pd δ+ species stabilized by abundant Pd–O–Ce interactions, as revealed by XPS analysis. Importantly, the optimized flame-made 5Pd/CeO 2 demonstrated remarkable stability and recyclability, significantly outperforming catalysts synthesized by incipient wetness impregnation or deposition-precipitation method and showing high efficiency (95% yield) in a preliminary continuous-flow reactor test. This work not only highlights FSP as a powerful and scalable method for the rational design of durable cross-coupling catalysts but also elucidates the critical importance of tuning Pd species at the metal–support interface to achieve high catalytic efficiency.