In Situ Visualization of Lattice‐Coherent Phase Oscillations and Active Brownian Motion of a Copper Catalyst During Hydrogen Oxidation

ratios (e.g., 5:1), featuring a metallic-rich head and an oxide-dominated tail, with their volumetric balance dynamically shifting through competitive oxidation-reduction cycles. Quantitative analysis establishes a direct correlation between migration velocity and redox dynamics, revealing that the oxidation process significantly enhances particle mobility while the followed reduction process slows the velocity. Molecular dynamics (MD) simulations demonstrate that particle elongation and oxide tail fragmentation, accompanying particle migration, can be explained by asymmetric adhesion forces between the metallic/oxide phases and the silicon nitride support, alongside the redox reactions occurring on the particles. This work provides atomic-scale insights into catalyst dynamics under operando redox conditions, offering foundational knowledge for designing stable, high-performance catalytic systems.