Electroreduction of oxygen on a (100)-like polycrystalline gold surface in an alkaline solution containing Pb(II)

Abstract

In a previous work from this laboratory, it was shown that it is possible to electrochemically modify a polycrystalline surface of gold so that it behaves towards O 2 reduction like the (100) gold plane. To check whether this similarity in behavior is due to the presence on the (100)-like surface of suciently large (100) spots, the process of the upd of Pb(II) was used in this work as a probe of the surface crystallographic orientations both in deaerated and in O 2 À saturated solutions. The observed cyclic voltammograms (CV) and polarization curves were entirely dierent from those reported in the literature for a typical polycrystalline gold surface. The CV data were analyzed in an attempt to gain insight on the crystallography of the (100)-like surface. The in¯uence of adsorbed lead on the electroreduction of oxygen in 1 M NaOH on the (100)-like surface was also scrutinised. It was found that the reduction is dierently aected by adsorbed Pb(II) ions and by underpotential deposited Pb adatoms. Adsorbed Pb(II) do not change the reduction mechanism, it only alters the rate constant for HO 2 À disproportionation, whereas the surface becomes able to reduce O 2 to OH À without desorption of HO 2 À to the solution bulk when modi®ed by Pb adatoms. The details of the electroreduction of O 2 and of HO 2 À are thoroughly discussed in relation to the surface processes underneath. Together with the CV data, they show that there are no signi®cant (100) spots on the (100)-like surface and that this surface is structurally dierent from the gold (100) plane. #

Electroreduction of Dioxygen on Polycrystalline Platinum in Alkaline Solution II. Platinum Surface Modified by Hydrogen Evolution

“…2a and b), in this return the polarization curve goes back through the same abovementioned stages that characterize the changing process toward the N-Pt surface. Once again, these observations remind us of the phenomena described for gold by Paliteiro et al 16 We also observed that the N-Pt surface obtained by fixing the upper potential at 1050 mV is not stable. The disk current intensity below 700 mV decreases every scan (in such a way that the N-Pt profile is maintained) until a stable surface configuration is reached; the initial N-Pt curves in Fig.…”

Electrocatalytic Reduction and Determination of Dissolved Oxygen at a Preanodized Screen‐Printed Carbon Electrode Modified with Palladium Nanoparticles

“…Compared to metal complexes and enzyme-based systems, metal electrodes were considerably attractive due to easy modification with tunable particle size characteristics. In recent years, variety of chemically modified metallic electrodes (e.g., Pt, Au, Ag and Pd) was developed for oxygen reduction reaction (ORR) with extraordinary catalytic feature over their bulk metal electrodes [7][8][9][10][11][12][13][14][15][16][17][18]. Although the initial Pt-based Clark O 2 electrode were effective, new chemically modified metallic electrodes to improve the catalytic efficiency and to eliminate the chloride interference are necessary for practical dissolved oxygen (DO) determination [19,20].…”

Quasi-reversible two-electron reduction of oxygen at iodine submonolayer-coated gold electrode in alkaline media

“…The ORR has been studied extensively using a large number of electrode materials with a view to clarifying its mechanism and to finding the highly active electrocatalysts for the reaction [1][2][3][4][5][6][7][8][9][10]. The metallic electrodes have been more widely investigated.…”