Electrodeposition of Pt-Ru nanoparticles on fibrous carbon substrates in the presence of nonionic surfactant: Application for methanol oxidation

Liquid crystalline and micellar aqueous solutions of the nonionic surfactant Triton X-100 were used to direct the electrodeposition of Pt-Ru nanoparticles onto graphite felts, which were investigated as novel anodes for the direct methanol fuel cell. The effects of surfactant concentration, current density and deposition time in the preparation of these three-dimensional electrodes were studied in a factorial experiment and the electrodes were characterized by SEM and ICP-AES. Cyclic voltammetry, chronoamperometry and chronopotentiometry were carried out to assess the activity of the catalyzed felts for methanol oxidation. The presence of Triton X-100 (40-60 wt.%) coupled with an acidic plating solution were essential for the efficient co-electrodeposition of Ru in the presence of Pt to yield approximately a 1:1 Pt:Ru atomic ratio in the deposit. The highest mass specific activity, 24 A g⁻¹ at 298 K (determined by chronoamperometry after 180 s at 0 V versus Hg/Hg₂SO₄, K₂SO_4std), was obtained for the Pt-Ru electrodeposited in the presence of 40 wt.% Triton X-100 at 60 A m⁻², 298 K for 90 min. Surfactant mediated electrodeposition is a promising method for meso-scale (ca. 10-60 nm diameter) catalyst particle preparation on three-dimensional electrodes.