Electrochemical kinetics of bismuth sulphide formation on bismuth amalgam

✍ Scribed by L.M. Peter; G.A. Wright

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 375 KB
• Volume: 32
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(87)85066-1

✦ Synopsis

A monolayer of bismuth sulphide was formed anodically on a hanging drop electrode of bismuth amalgam in aqueous NaHCO, solution containing HS-at 20°C. Potential sweep experiments showed a monolayer current peak with a charge density of 430 &cm-', in close agreement with the value predicted from the (010) plane of orthorhombic bismuth-sulphide, with chains of (Bi&)_ on the electrode surface. The monolayer peaks of HgS were suppressed by prior formation of the Bi,!& monolayer, and a mixed film of Bi,S, and Bi,Oa formed at a higher overpotential. Galvanostatic transients gave a small nucleation peak, followed by growth at a constant overpotential until the monolayer was complete. Potentiostatic transients showed an asymmetric current peak indicating that the mechanism of monolayer formation involves instantaneous nucleation followed by expansion and overlap of two-dimensional centres.