Sphere-Cap Mercury Microelectrodes for Scanning Electrochemical Microscopy Above an Insulating Substrate

✍ Scribed by Salvatore Daniele; Carlo Bragato; Ilenia Ciani; M. Antonietta Baldo

• Book ID: 102181051
• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 120 KB
• Volume: 15
• Category: Article
• ISSN: 1040-0397
• DOI: 10.1002/elan.200390078

✦ Synopsis

Abstract

Sphere‐cap mercury microelectrodes, fabricated onto platinum microdisks 1 and 10 μm radius, were employed as tips in scanning electrochemical microscopy (SECM). Experimental current vs distance curves were acquired above an insulating substrate with a series of sphere caps whose aspect ratio h/a (h is the height of mercury deposit, a is the disk basal radius) varied between 0.28 and 2.14. It was found that the hindered diffusion effect of the insulating surface was the less pronounced the higher was the h/a parameter of the sphere cap. Comparison of experimental and theoretical approach curves displayed a fairly good agreement for subhemisphere caps (h), and a less satisfactory agreement for hemispherical (h=a) and superhemispherical (h>a) caps. Preliminary coupled anodic stripping voltammetry and SECM measurements were also performed for the investigation on local chemical equilibria involving heavy metals at sediment/water interfaces.