Strain-Induced Corrosion Kinetics at Nanoscale Revealed in Liquid: Enabling Control of Corrosion Dynamics of Electrocatalysis

SummaryCorrosion at the nanoscale is vital for the stability of nanoparticles. Understanding the corrosion mechanism can offer insights on how to design more stable nanoparticles during electrocatalysis, such as oxygen reduction reaction (ORR). Here, using a liquid cell (LC) transmission electron microscopy (TEM) technique, we study the corrosion process of palladium@platinum (Pd@Pt) core-shell octahedra at real time. The results revealed that the nanoscale corrosion kinetics was determined synergistically by both the quasi-static factor, local strain, and dynamic factor, local curvature. Specifically, in locations with tensile strain and high local curvature, the etching process is much faster than other places. Density functional theory (DFT) calculation suggested that the dissolution potential of the nanoscale Pd nanocrystal is decreased by the increasement of the strain and meanwhile the calculation indicated that the nanoscale surface Pd atoms trended to be corroded more easily under tensile strain than that under compressive strain. Through the investigation of the nanoscale corrosion mechanisms above, we subsequently designed and synthesized a nanoparticle with smaller strain, which showed higher durability both in in-situ liquid cell and ex-situ ORR stability test.