Model Electrode Studies of the Electrostatic Interaction between Electrochemically Dissolved Pt Ions and RuO2 Nanosheets

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 × 106 atoms μm−2, which agreed with the theoretical saturated adsorption amount of Pt ion on RuO2 nanosheet of 0.96 × 106 atoms μm−2. All of the Pt ions could be electrochemically reduced to Pt nanoparticles showing activity toward the oxygen reduction reaction. © 2013 The Electrochemical Society. [DOI: 10.1149/2.050403jes] All rights reserved.