Chemically modified electrode (CME) is the
modern approach to the electrochemistry. It find wide spectrum of basic
electrochemical investigation, including the relationship of heterogeneous electron transfer , chemical reactivity to electrode surface chemistry, electrostatic process at
the electrode surfaces, electron and
ionic transport process in polymers, design of
electrochemical devices and
system for application in chemical sensing, energy conversion and storage,
molecular electronics, electrochromic
display, corrosion protection and electro-organic syntheses. CME is the thin
film of monomolecular to a few micrometers
of selected chemical is bonded or coated onto the electrode surface to provide the electrode with chemical, electrochemical, optical,
electrical, transport and other
desirable properties of the film
in a chemically designed manner. CME provides a higher rate for the
electrode reaction, reproducibility and even applicability. In the simplest
approach, a CME with a surface-bound moiety capable of promoting or catalyzing
the oxidation or reduction of the electroactive species. . CME itself act as
the reactant species to pump (reduction) / withdraw (oxidation) electron in the
reaction while in other spectroscopic application, this is not possible.
The
concept of CMEs was developed in mid 70s when the
electrochemist studied the nature of CME. But applied in late 90s because of the
development of polymer electrode film. In early years, CME is prepared by
covalent bonding and chemisorptions are
tedious, time consuming, poor reducibility, and a short lifetime. Polymer film
electrode offers a higher surface concentration of active sites (about 10-10
– 10 -6 mol/ cm2) and a very
sensitive electrochemical
response, easy ease of preparation, stable attachment, long electrode lifetime, as well as suitable spatial,
electrostatic, and chemical microenvironments constructed on the electrode surface.
The most common inorganic polymer films
include. prussian blue and its analogs [6-81, montmorillonite clays , zeolite.Chemically modified carbon paste electrode (CMCPEs) is
extremely attractive features for repetitive measurements. Various modifiers
such
as
organic and inorganic polymers, ion exchange resins, insoluble organics and
inorganics have been attachemed in CMCPEs.