Oscillating Dynamics of Migrating Cu-Pd Bimetallic Particles in the Catalytic Redox Reaction

Increasing evidence from in situ investigations discloses that nanoparticles (NPs) undergo reconstruction and migration during catalytic redox reactions. Insights into the driving mechanism are significant but remain rare for understanding NP-localized reaction kinetics while attenuating catalyst coarsening. Herein, tracking the restructuring of Cu-Pd bimetallic NPs in a redox atmosphere through environmental transmission electron microscopy, we unraveled non-equilibrium oscillating dynamics facilitating the continuous migration of a tadpole-like Cu_xPd/Cu₂O nanostructure. The spatially asymmetric distribution of Cu-Pd bimetallic and Cu₂O phases within individual NP dictates its movement under the driving force of the copper redox reaction. Time-resolved microstructure tracking revealed that this oscillation was caused by the asynchronous diffusion of H₂/O₂ reactants. In situ microscopy results further evidenced that the oscillatory migration starts from the oxidation of Cu atoms into Cu₂O at low-coordinated corner sites of the Cu-Pd NP. This work comprehends the mechanism of widely observed catalytic NP oscillation and migration, which inspires an in-depth understanding of the intrinsic nature of NP migration coarsening.