Search for surface structural effects in electrocatalysis. I. Smooth platinum electrodes

Abstract

Platinum electrodes were pretreated in various ways with the aim of producing surfaces of different structure. The adsorptive properties were studied using linear sweep voltammetry, and the activity for the anodic oxidation of methanol was determined using a multi-pulse potential program. Although chemical etching and different kinds of heat treatment altered the hydrogen adsorptive properties of platinum, the specific activity for methanol oxidation was not significantly affected. A relationship between the shapes of anodic voltammograms in the hydrogen region and at the start of the oxide region was noted and used in deducing the nature of the adsorbed oxygen-containing species and its involvement in the methanol oxidation reaction. Electro- chemical activation of cold-worked electrodes was attributed to the removal, by anodic dissolution, of a structurally disturbed layer of surface platinum atoms of lower activity than a crystalline surface. The activity of platinum for methanol oxidation was concluded to be a property of a well-ordered crystalline surface, independent of orientation.