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

Developing robust and recyclable heterogeneous catalysts for the Suzuki-Miyaura cross-coupling (SMC) reaction is crucial for sustainable chemical synthesis. Herein, we address this challenge through the nanoscale engineering of palladium/ceria (Pd/CeO2) 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/CeO2 (5Pd/CeO2) catalyst exhibiting the highest catalytical performance in mild conditions (97% yield, turnover number = 19.4). This superior activity was attributed to highly dispersed interfacial Pdδ+ species stabilized by abundant Pd-O-Ce interactions, as revealed by XPS analysis. Importantly, the optimized flame-made 5Pd/CeO2 demonstrated remarkable stability and recyclability, significantly outperforming a conventional incipient wetness catalyst 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 speciation at the metal-support interface to achieve high catalytic efficiency.