First-principles investigation of electrochemical dissolution of Pt nanoparticles and kinetic simulation.

Dissolution is the primary route of Pt nanoparticle degradation in electrochemical devices, e.g., fuel cells. Investigation of potential-dependent dissolution kinetics of Pt nanoparticles is crucial to optimize the nanoparticle size and operating conditions for better performance. A mean-field kinetic theory under the steady-state approximation, combined with atomistic thermodynamics and Wulff construction, was developed to study the interplay between oxygen chemisorption, electrode potential, and particle size on the dissolution of Pt nanoparticles. We found that although oxygen chemisorption from electrode potential-induced water splitting can stabilize Pt nanoparticles through decreasing the surface energy and increasing the redox potential, the electrode potential plays a more decisive role in facilitating the dissolution of Pt nanoparticles. In comparison with the minor effect of oxygen chemisorption, an increase in the particle size, though reducing the dispersion, has a more significant effect on the suppression of the dissolution. These theoretical understandings on the effects of electrode potential and particle size on the dissolution are crucial for optimizing the nanoparticle size under oxidative operating conditions.