Adsorption of Organic Species on Platinum Metal Electrodes

Electrooxidation of methanol on doped polypyrrole films in acidic media

“…In addition to the strong Pt 4f peak a strong Cl 2p peak at around 207 eV binding energy which is assigned to ClO 4 − is observed. However, no strong ClO 4 − could be observed at −0.6 V as is shown in Fig. 3iii.…”

“…The kinematically fast proton expulsion that takes place in the early part of the oxidation process is superseded at higher potentials by the thermodynamically favoured influx of anions. The stability of the ClO 4 − doped Pt/PPy/Ni electrodes is found to be good. The doped electrodes exhibited better electrocatalytic activity when compared with Pt/PPy/Ni or Pt.…”

“…Additionally, it is well known that the counterion can effect the PPy film morphology and the conductivity [29]. So, the higher activity obtained with ClO 4 − doped Pt/ PPy/Pt -Ni electrodes may be explained as due to the protective effect against the poisoning reactions of methanol oxidation by an increase in the conductivity and change in morphology when compared with platinum dispersed in PPy films. The degrees of freedom available to modify the electrochemical properties of a polymer by changing [25] report current densities of about 20 mA cm − 2 (geometric area) for Nafion ® films about 200 mm thick loaded with 4-8 mg cm − 2 of platinum, recorded in 1.0 M H 3 PO 4 containing 1.0 M methanol at 600 mV/RHE.…”

“…Upon further anodic oxidation in the reversible potential region, the polymer is transformed to the radical cation and anions are inserted into the solid to maintain electroneutrality. So, ClO 4 − anions are entrapped via Coulombic interaction with the positively charged polymer segments keeping their electrocatalytic properties. The presence of ClO 4 − anions is confirmed by XPS analysis on the doped polymer matrix at +0.8 V/ MSE.…”

“…So, ClO 4 − anions are entrapped via Coulombic interaction with the positively charged polymer segments keeping their electrocatalytic properties. The presence of ClO 4 − anions is confirmed by XPS analysis on the doped polymer matrix at +0.8 V/ MSE. We have checked the doped surface on a Ni substrate by XPS and no peak assignable to the substrate could be observed.…”