A 'redox electrode' is an
electrode made from electron-conductive material and characterized by high
chemical stability in the solution under test. It is used for measuring the
redox potential of a specific
redox system in solution, and for
electrochemical studies (investigation of electrochemical
kinetics of interfacial processes).
The correlation of an electrode potential and redox system composition can be described by the
Nernst equation:
:Ox + ne
- = Red
:
,
where
:''E''
0 -
standard potential of a specific redox system,
:''R'' -
gas constant,
:''T'' -
temperature in
kelvins,
:''n'' - number of electrons taking part in a specific redox reaction,
:''F'' -
Faraday constant
:''a''
ox, ''a''
red -
activity of oxidising and reducing participants in redox reaction.
There are two general classes of redox electrodes:
★
metals (the most common are
platinum and
gold, but for special purposes other materials such as
titanium or
iridium can be used)
★
semiconductors (the most common are
graphite,
diamond, and
SnO2)
Illustration
A gold disk redox electrode with a Teflon shroud insulating the disk.
See also
★
Reference electrode
★
Flow battery