Interfacial\nReactivity-Triggered Oscillatory Lattice\nStrains of Nanoalloys

Understanding\nthe structure evolution of nanoalloys under reaction\nconditions is vital to the design of active and durable catalysts.\nHerein, we report an operando measurement of the dynamic lattice strains\nof dual-noble-metal alloyed with an earth-abundant metal as a model\nelectrocatalyst in a working proton-exchange membrane fuel cell using\nsynchrotron high-energy X-ray diffraction coupled with pair distribution\nfunction analysis. The results reveal an interfacial reaction-triggered\noscillatory lattice strain in the alloy nanoparticles upon surface\ndealloying. Analysis of the lattice strains with an apparent oscillatory\nirregularity in terms of frequency and amplitude using time-frequency\ndomain transformation and theoretical calculation reveals its origin\nfrom a metal atom vacancy diffusion pathway to facilitate realloying\nupon dealloying. This process, coupled with surface metal partial\noxidation, constitutes a key factor for the nanoalloy’s durability\nunder the electrocatalytic oxygen reduction reaction condition, which\nserves as a new guiding principle for engineering durable or self-healable\nelectrocatalysts for sustainable fuel cell energy conversion.