Ni0.3Co2.7O4 spinel particles/polypyrrole composite electrode: Study by X-ray photoelectron spectroscopy

In this work we have studied the multilayered polypyrrole/oxide composite electrode on glassy carbon having the structure GC/PPy/PPy(Ni0.3Co2.7O4)/PPy, in which the spinel oxide Ni0.3Co2.7O4 is known to be an electrocatalyst of the oxygen reduction reaction in alkaline medium. The successive GC/PPy, GC/PPy/PPy(Ni0.3Co2.7O4) and GC/PPy/PPy(Ni0.3Co2.7O4)/PPy parts of the electrode were examined by X-ray photoelectron spectroscopy. The results indicate that the electronic structure of the PPy is independent of the thickness of the PPy used to prepare the electrodes. The XPS data also show that cobalt is present in both divalent and trivalent states. The PPy doping degree by Cl- ions (in terms of the Cl-/N) and the oxide/PPy mass ratio observed by XPS were 19 and 4.5%, respectively