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

Increasing evidence from <i>in situ</i> 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_<i>x</i>Pd/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. <i>In situ</i> 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.