A Ring-Disk Study of HOBr Formation at Platinum Electrodes in 1.0M H[sub 2]SO[sub 4]

The rotating ring‐disk electrode (RRDE) was used to study the oxidation of Br − at platinum electrodes in 1.0 M supporting electrolyte. In addition to the electrochemical oxidation of Br − to Br 2 by a convective‐diffusion controlled reaction, a small amount of HOBr was produced by oxidation of adsorbed Br − with concurrent oxidation of the platinum electrode surface. Bromide does not adsorb at an anodized platinum surface, whereas adsorption is very rapid at a reduced platinum surface. The equilibrium surface coverage by Br − corresponds to a monolayer for bulk concentrations of KBr greater than