Rotating Ring-Disk Study of the Reduction of Oxidized Platinum by Mercurous Mercury and Its Adsorption on Reduced Platinum

A potential-time study at a rotating platinum disk electrode showed that Hg(I) in 1.0M HClO, reduces an oxidized platinum surface. Using a rotating platinum ring-disk electrode, the time-dependent ring collection curves demonstrated that the amount of Hg(II) produced was less than the amount of Hg(I) consumed during the reduction of the oxidized platinum surface. The quantity of Hg(II) produced agreed with the electrical charge required to reduce the oxidized platinum surface. The difference between the amount of Hg(I) consumed and Hg(II) produced (357±47),㊼C/cm² corresponds to the amount of Hg(I) adsorbed on a reduced Pt surface. The quantity of adsorbed Hg(I) was independently established by determining the charge (1) required for reduction to Hg(0) on the disk; (2) required for oxidation to Hg(II) on the disk before and after reducing the disk; and (3) corresponding to the amount of Hg(II) produced in (2) using the ring electrode.