An improved electrodeposition technique for preparing platinum and platinum-ruthenium nanoparticles on carbon nanotubes directly grown on carbon cloth for methanol oxidation

Platinum (Pt) and platinum-ruthenium (Pt-Ru) nanoparticles were successfully electrodeposited on dense carbon nanotubes (CNTs) directly grown on carbon cloths in ethylene glycol (EG) containing H2SO4 aqueous solutions. It was found that EG enhanced the dechlorination of Pt and Ru precursor salts and led to the formation of nanoparticles. In the meantime, it also acted as a stabilizing surfactant to prevent the particles from agglomeration during the electrodeposition processes. Nano-sized Pt and Pt-Ru particles were found in specimens treated at two pre-selected negative potentials. The particle sizes of Pt on CNTs ranged from similar to 4.5 to similar to 9.5 nm while those of Pt-Ru on CNTs (Pt-Ru/CNTs) ranged from similar to 4.8 to similar to 5.2 nm, as estimated from transmission electron microscopy. Electrochemical characteristics of methanol oxidation on these catalysts were investigated via cyclic voltammetry analysis in mixed 1 M CH3OH and. 0.5 M H2SO4 solutions. The efficiency of the Pt-Ru/CNTs electrode on methanol oxidation in terms of mass activity (normalized current density of methanol oxidation per gram of Pt loading) and of the ratio of forward peak current density to reverse peak current density was far superior to that of a commercial electrode with Pt-Ru supported on carbon black, clearly indicating a significantly improved catalytic activity of the new Pt-Ru/CNTs electrode prepared by electrodeposition in the EG containing solution. (c) 2006 Elsevier B.V. All rights reserved.