Gas-pressure-assisted strategy for precise control of palladium-based nanoparticle sizes: Unveiling size effects on...

Understanding the relationship between catalyst particle size and activity is crucial for developing efficient catalytic systems. However, the size-dependent behavior of Pd-based alloy catalysts remains poorly understood, requiring a comprehensive investigation. This study presents a straightforward and effective gas-pressure-assisted heat-treatment method that allows precise control over the particle sizes of various Pd-based catalysts, including Pd, Pd₃Fe, Pd₃Co, Pd₃Ni, and Pd₃Cu. Our findings demonstrate that high pressure significantly inhibits nanoparticle sintering by increasing energy barriers for both metal atomic diffusion and nanocluster migration. A linear relationship has been established between average particle size and applied gas pressure. Specifically, this method was employed to synthesize Pd₃Fe nanoparticles (NPs) with an average particle size ranging from 2.8 to 6.9 nm. Furthermore, we explored the size effect of Pd₃Fe/C in the methanol oxidation reaction (MOR). The mass activity (MA) of the catalyst exhibited a volcano-shaped trend as particle size decreased. Notably, the Pd₃Fe/C-7 MPa catalyst with a particle size of 3.9 nm demonstrated superior MA compared to other samples within this range of sizes tested in this study. This work offers a valuable approach for systematically studying the size effect on catalytic performance, which aids researchers in designing high-performance catalytic materials.