Mechanistic Insights of Support Dynamics During Reactive Metal-Support Interaction

Reactive metal-support interactions (RMSI) are pivotal preparatory steps in the synthesis of many supported bimetallic nanoparticles. However, there is still a knowledge gap regarding the precise mechanics of such interactions, especially regarding support activation. The present study investigates the reduction of PdO nanoparticles supported on ZnO and the formation of the intermetallic compound ZnPd, using environmental scanning transmission electron microscopy (E-STEM). The ZnO support is activated due to hydrogen spillover from the nanoparticle, which then migrates to the nanoparticle and thereby forms an encapsulation layer. Subsequently, Zn is reduced to the metallic state and diffuses into the Pd lattice at the interface, forming ZnPd and resulting in partial core-shell structures. Structural analysis reveals that intermetallic ZnPd phase growth is diffusion-controlled and facilitated by interfacial nucleation. These findings provide mechanistic insights into reactive metal-support interactions, demonstrating the structural evolution of the supported catalyst system during reduction.