Model electrodes consisting of ruthenium oxide nanosheets coated on freshly cleaved highly oriented pyrolytic graphite (RuO2 nanosheet/HOPG) were prepared to investigate the electrostatic interactions between RuO2 nanosheets and electrochemically dissolved Pt ions. The RuO2 nanosheet/HOPG model electrode was dipped into a solution containing dissolved Pt ions generated by potential cycling a Pt working electrode in sulfuric acid electrolyte. Scanning tunneling microscopy revealed preferential adsorption of Pt ions on the nanosheets as island-like deposits, while no such deposits were observed on HOPG. This shows the strong electrostatic interactions between the positively-charged Pt ions and negatively-charged nanosheet. The calculated amount of Pt ions adsorbed was 0.93 x 10(6) atoms mu m(-2), which agreed with the theoretical saturated adsorption amount of Pt ion on RuO2 nanosheet of 0.96 x 10(6) atoms mu m(-2). All of the Pt ions could be electrochemically reduced to Pt nanoparticles showing activity toward the oxygen reduction reaction. (C) 2013 The Electrochemical Society. All rights reserved.