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Electrochemical Nucleation of Platinum on Carbon Materials and Ruthenium Thin Films

The aim of this work is to study the electrocrystallization of platinum onto different substrates such as glassy carbon (GC), highly oriented pyrolytic graphite (HOPG), and the thin film of ruthenium. Electrodeposition was performed from a solution containing hexachloroplatinum ions using cyclic voltammetry and chronoamperometry. Electrodeposition of Pt on carbon substrates occurs according to the Volmer-Weber island growth mechanism due to a weak carbon substrate-Pt deposit interaction. At relatively low overpotentials, the electrodeposition is mainly initiated on steps and other surface defects. Analysis of potentiostatic pulse measurements on electrodes of carbon materials showed the 3D instantaneous nucleation and growth under the diffusion control. Parameters obtained from the applied model are the density of growing nucleation centers of Pt (10^9-10^10 cm^-2), and the stationary rate of nucleation (10^3 s^-1). The morphological study performed by SEM gave the uniformly distributed and monodispersed nanoparticles of Pt catalyst on carbon substrates. Ruthenium as a metallic substrate gave quite different image of Pt deposits than carbon materials, because of the stronger Ru– Pt interaction. Deviation from the classical nucleation models pointed to the alloy formation by 2D instantaneous nucleation mechanism.

Platinum; Ruthenium; Nucleation; Glassy carbon (GC); Highly oriented pyrolytic graphite (HOPG); 3D instantaneous nucleation; 2D instantaneous nucleation.

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