Search for surface structural effects in electrocatalysis. II. Platinized platinum electrodes

Abstract

The adsorptive properties of platinized electrodes, as indicated by cyclic voltammetry, depended on the potential of platinum electrodeposition. Electrodes deposited above 0.05 V v. reversible hydrogen electrode were similar to smooth platinum, while those deposited at negative potentials showed anomalous behaviour, particularly with regard to hydrogen sorption. Measurements with such electrodes over a range of sweep rates showed slow sorption of about two hydrogen atoms in excess of the usual fast adsorption of one hydrogen atom per surface platinum atom. Freshly electrodeposited platinum had a specific activity for methanol oxidation of one-quarter to one-half that of smooth platinum. The lower activity was attributed to the effects of disordered surface structure and/or small particle size. Anodic-cathodic cycling produced surface recrystallization and activities close to that for smooth platinum.