CO adsorption and oxidation on Pt and PtRu alloys: dependence on substrate composition

✍ Scribed by R. Ianniello; V.M. Schmidt; U. Stimming; J. Stumper; A. Wallau

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 695 KB
• Volume: 39
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(94)85176-x

✦ Synopsis

Adsorption and electrooxidation of CO on polycrystalline Pt and Pt-Ru alloys (Pt,,,Ru,,, , Pt, .Ru, .) has heen studied by means of in situ infrared (FTIR) swctroscoDy and differential electro-".. ".", chemical mass spectrometry (D-EMS). Within the resolutiod limits dr this stud; (AR/R = 10T3) only one adsorbed CO(a) species at v x 2070-2075cm-' (pt) and 2050-206Ocm-' (I+Ru) was detected. No significant difference in C-O frequency between F't,,,Ru,,, and Pt,,,Ru,-,, was found. The oxidation of CO adsorbed in the hydrogen region on pt-Ru shows distinct diierences when compared with a polycrystalline Pt electrode. Whereas on Pt the oxidation of CO proceeds in two stages, on Pt-Ru cyclic voltammetry shows only one oxidation peak at a less positive potential compared to Pt. The lowest peak potential for CO adsorbate oxidation was observed on Pt,.,Ru,,, at about 380mV vs. rhe. The results for CO oxidation obtained on Pt and Pt,.,Ru,,, deposited onto a porous Au substrate by on line mass spectrometry were in accordance with the ir spectroscopic data It was shown that Ru atoms at the surface of a Pt-Ru bimetallic electrode increase the CO tolerance of the catalyst. The promoter effect of Ru is explained with the biiunctional mechanism for CO oxidation where oxygen containing species are bounded preferentially to ruthenium surface atoms.