Imaging the strain evolution of a platinum nanoparticle under electrochemical control

International audience; Surface strain is widely employed in gas phase catalysis and electrocatalysis to control the binding energies of adsorbates on active sites. However, in situ or operando strain measurements are experimentally challenging, especially on nanomaterials. Here, we exploit coherent diffraction at the new 4 th generation Extremely Brilliant Source at the European Synchrotron Radiation Facility (ESRF-EBS) to map and quantify strain inside individual Pt catalyst nanoparticles under electrochemical control. 3D nanoresolution strain microscopy together with density functional theory and atomistic simulations show for the first time evidence of heterogeneous and potential-dependent strain distribution between highly-coordinated ({100} and {111} facets) and under-coordinated atoms (edges and corners) as well as evidence of strain propagation from the surface to the bulk of the nanoparticle. These dynamic structural relationships directly inform the design of strain-engineered nanocatalysts for energy storage and conversion applications.