Preparation of Platinum Cluster-Impregnated Electrodes and Their Methanol Electrooxidation Characteristics

Abstract

Platinum cluster-supported electrodes were prepared from Pt and Ru carbonyl complexes. [Pt₃(CO)₆]_n2M(n=3, 5), [PtCl₂(SnCl₃)₂]2M, [Pt₃Sn₈Cl₂₀]4M, [Pt₃Fe₃(CO)₁₅]2M and [HRu₃(CO)₁₁]M (M=Na⁺, NMe₄⁺, NEt₄⁺, NMe₃(CH₂ph)⁺) as precursors by an ion-exchange tech nique on an anion type solid polymer electrolyte membrane or an graphite which was surfacemodified with a silanizer of quarternary ammonium salt. The cluster-supported electrodes with Pt₉/C Pt₁₅/C but not with Pt or Pt₃, revealed a high level of electrocatalytic activity towards the anodic methanol oxidation in acidic Media. The specific activity was 0.5-1orders of magnitude higher than that of Pt electrode of ordinary type. Mixing of Pt and Ru clusters give improved activity on C but not on SPE. In Pt-Sn clusters, Pt₃Sn₃/C give noticeable activity only after strong anodic treatments. The amount of Pt required for methanol fuel cell may be decreased by this technique of preparing Pt in a highly dispersed state. It was found that catalytic activity towards the methanol electrooxidation of the Pt cluster-supported electrodes greatly depended upon the Pt size of clusters.