The electrodeposition of Pt on RuO 2(110) from acid solutions of several Pt complexes was studied using programmed potential step or potential sweep methods. The RuO 2(110) single-crystal surface was obtained by gas-phase oxidation of Ru(0001). The electrodeposition process is characterized by a large crystallization overpotential and three-dimensional growth from a Pt adlayer. The mismatch between the RuO 2(110) and Pt lattices is the likely origin of that overpotential. The nucleation is instantaneous, as verified by potential step experiments. The process starts with depositing a 0.25 ML of Pt, with Pt atoms arranged in a c(2 × 2) array, which is followed by the growth of Pt islands and three-dimensional clusters as in the Stranski-Krastanov growth mode. Density functional theory calculations were used to help in elucidating atomically resolved electrochemical scanning tunneling microscopy (ECSTM) images of the initial stages of Pt deposition. A Pt adlayer on RuO 2(110) has lower catalytic activity for the oxygen reduction reaction compared to Pt, which is in agreement with a large calculated upshift of the d-band center of a low-coverage Pt deposit on RuO 2-(110) as well as a lack of the oxygen adsorption in a bridge configuration on that surface.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films