Applications of redox contacts for metal and semiconductor rotating ring-disk electrodes.

A design of a rotating ring-disk electrode with an electrolytic back contact cell for the disk has been implemented and tested. Both the disk, acting as a bipolar electrode between a conventional cell and back compartment, and the back electrolyte are made readily interchangeable. Major application is to semiconductor disks where ohmic contacts may be intricate to fabricate, as for the p-InP example experimentally investigated here. Control of the back cell characteristics with a metallic disk allows selective response to mixed redox couples, illustrated by amperometric end point detection in titrimetry.