Ring-Disk Electrode Study of the Reduction and Oxidation of Bismuth on Gold

The deposition and stripping of bismuth at a gold electrode was studied in 0.12M perchloric acid. Current-potential curves show four cathodic and four anodic processes at ED < + 0.40V vs. SCE. Three of these processes correspond to the deposition and stripping of Bi(O) at underpotential. A maximum of one monolayer of Bi(O), corresponding to 590 /xcoulombs/cm2 at ‘0.05V, was deposited on the electrode at underpotential. The fourth process was the deposition and stripping of bulk bismuth. The diffusion coefficient of Bi(III) was found to be 5.8 x 10 ~6 cm2/sec. No Bi-Au alloy formation was observed. Bi(III) was found to adsorb on gold oxide. The quantity adsorbed is a function of the oxidation potential of the electrode and the concentration of Bi(III).