Platinum oxide film formation—reduction: an in-situ mass measurement study

Abstract

The growth and reduction of oxide films at Pt was studied using the quartz crystal microbalance technique. The compact α-oxide was shown to be anhydrous in nature (either PtO or PtO 2). When the potential was extended into the hydrogen adsorption region, the electrode mass was seen to decrease, but then stabilized once the hydrogen evolution reaction commenced. These results, as well as the effect of the addition of chloride and ferrous ions on the mass measurements, have been interpreted in terms of ion adsorption—desorption processes. The mass change during the reduction of thin hydrous β-oxide films was also monitored and yielded a mass-to-charge ratio consistent with a PtO(OH) 2 film composition. Other mass data indicated that Pt dissolution can occur with repeated β-oxide growth—reduction cycles and that some Pt may redeposit, given sufficient time at negative potentials.