Nucleation and Growth of Dendritic Islands during Platinum Oxidation-Reduction Cycling

Platinum is the model catalyst in fuel cells because of its high activity toward oxygen reduction and hydrogen oxidation. However, applicability limited due to degradation under operating conditions. This process has been extensively studied by repeatedly oxidizing reducing electrode, which leads roughening surface nucleation growth platinum nano-islands. Although general picture this well known, atomic details concerning early islands are still debate. In work, we use Density Functional Theory (DFT) calculate formation energies diffusion barriers an adatom, both unoxidized oxidized state, with aim provide further insight into phenomena. Moreover, analyze from STM images obtained experimentally shape nano-islands during first stages growth. Our results show not only that form surface, but also they grow a dendritic island shape, similarly formed vacuum Molecular Beam Epitaxy (MBE).