XPS investigation of surface oxidation layers on a platinum electrode in alkaline solution

✍ Scribed by M. Peuckert

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 651 KB
• Volume: 29
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(84)87003-6

✦ Synopsis

thick oxidation layer on a platinum electrode has been grown in 1 N NaOH at 3 V us Ag/AgCI reference electrode. After transferring the Pt electrode into an ultrahigh vacuum chamber the surface layer was analysed by X-ray photoelectron spectroscopy. Pt4f,,,, Pt4f,,, and 01s electron binding energies of 74.3, 77.6 and 530.9 eV respectively, as well as the broad peak shape of the 01s signal and the oxygen-toplatinum intensity ratio of 3.08 point towards a platinumoxyhydroxide PtO(OH),. This formula is in good agreement with cyclic voltammetry curves, measured for the same electrode, that revealed two cathodic reduction peaks for oxygen surface coverages equivalent to more than two hydrogen monolayers. These two peaks were assigned to Pt-OH and Pta. XPS analysis at elevated temperatures showed that the thick (z 5 am) oxidation layer decomposes at 400 K to a mixture of several oxides and hydroxides of PtqC and Pt'* and Pt metal with a ratio of 0-to-Pt of 1. This mixture further gradually decomposes to only a monolayer ofoxygen at 77G870 K. Sodium cations were found to be present in trace amounts in the adlayer and to strongly shift the 01s binding energy to lower values.