Electrooxidation of Stepped Pt Crystals and its Influence on Pt Dissolution

Pt nanoparticle degradation in PEMFCs, primarily through electrooxidation and dissolution, limits catalyst durability. While studies on low-index Pt single crystals have revealed facet-dependent mechanisms, oxidation at defect sites—dominant in real catalysts and oxidized at lower potentials—remains unexplored. We propose operando high-energy surface X-ray diffraction (HESXRD) to investigate atomic-scale structural changes during electrooxidation and anion-modulated dissolution on stepped Pt surfaces. This work aims to elucidate the potential-driven evolution of step oxide structure and dynamics under operating conditions, providing fundamental insights for designing stable Pt electrocatalysts.