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Title: Au-Pd core-shell nanoparticles: Understanding colloidal bimetallic catalysts using (in situ) transmission electron microscopy

Abstract: The atomic distribution of elements within a bimetallic nanoparticle can have a large impact in the catalytic properties of bimetallic nanoparticles. In particular, Au-Pd core-shell nanoparticles are promising for selective hydrogenation catalysis, exhibiting up to 50 times higher catalytic activity than their alloyed counterparts, while retaining high selectivity [1]. In the course of my PhD, we 1) used colloidal synthesis to make size, shape and composition controlled Au-Pd core-shell nanoparticles, 2) tested them in selective hydrogenation reactions and 3) used (in situ) transmission electron microscopy (TEM) as a core technique to characterize and understand how the nanoparticles can change under operating conditions. In this talk, I will give an outline on three different works. First, we will discuss how the catalytic properties of core-shell catalysts are distinct from those of alloys or monometallic counterparts in the liquid-phase selective hydrogenation of MBY. Then, we will discuss how we can assess the gas-dependent atomic distribution using in situ TEM, and how the alloying process of core-shell nanoparticles is affected by the gas atmosphere [2]. Last but not least, I will discuss how we can use 4D-STEM to do strain mapping at sub-nanometer resolution to observe the incorporation of hydrogen in a Pd lattice, forming palladium hydride [3].  

1. van der Hoeven, J. E. S. et al. Unlocking synergy in bimetallic catalysts by core–shell design. Nat. Mater.20, 1216–1220 (2021). 

2. Perxés Perich, M. et al. In situ analysis of gas dependent redistribution kinetics in bimetallic Au-Pd nanoparticles. J. Mater. Chem. A 12, 32760–32774 (2024). 

3. Perxés Perich, M., Lankman, J.-W., Keijzer, C. J. & van der Hoeven, J. E. S. In Situ Gas-Phase 4D-STEM for Strain Mapping during Hydride Formation in Palladium Nanocubes. Nano Lett.25, 5444–5451 (2025).