Unveiling the Effects of Adsorbates on Pt Nanoparticle Crystal Structure during an Electrocatalytic Reaction

Understanding reaction mechanisms remains one of the central challenges in electrochemistry. Gaining insight into how reactions proceed at the molecular scale is crucial for improving catalytic performance. However, most available methods focus on tracking solution-side dynamics, offering limited understanding of how adsorbates influence the catalyst itself. Here, we directly probe the structural dynamics of a single Pt nanoparticle under electrochemical control by monitoring its strain evolution with Bragg coherent diffraction imaging, using the electrooxidation of glycerol as a proof-of-concept reaction. We observe potential-dependent distortions in the catalyst crystal induced by dynamic changes in surface adsorbates, allowing us to visualize how these species modulate the electrocatalyst structure during operation. Strain mapping reveals facet- and potential-dependent behavior that correlates with adsorbate density. Moreover, mechanical strain accommodation acts alongside the adsorbate-induced strain to shape the structural response, while surface defects can dominate the local strain distribution. These findings demonstrate how the interplay between surface chemistry, structure, and mechanical strain, often overlooked in mechanistic studies, plays a decisive role in electrocatalysis.