User:Jgonzalez2015/Chemically Modified Electrodes

Chemically Modified Electrodes ...are electrodes covered in a small film of a chemical that will give it certain wanted chemical, optical or electrochemical properties. Royce Murray and his colleagues introduced these electrodes in the 1970s which allowed for extensive research for how these electrodes could be produced and how they could be used. (Mukhopadhyay 2008)

History
Chemically modified electrodes were first introduced in the late 1960s early 1970s by Royce Murray and his colleagues at the Gordon Research Conference on electrochemistry. He gave way for extensive research on the subject and was later asked to be part of IUPAC a group that gave terminology and definitions in the field of CME's. (Mukhopadhyay 2008)

Processes for Making CMEs
These electrodes can be manufactured in a range of manners to get the desired properties from the electrodes.

Chemisorption
This manner of producing CME's is done by allowing the conductor at hand to absorb properties of an electrode by creating a new layer on the conductor film making a new layer that lies on top of the conductor. This is the simplest way of producing CME's but when chmisorption is taking place the new electrode surface tends to occur at specific sites of the conductor making it inefficient.

Covalent Bonding
In Covalent bonding other chemical agents are used so that the chemical modifiers that want to be applied to the electrode are bonded by the sharing of electrons. This process overs more surface area than chemisorption process...(need to finish)

Polymer Film Coating
Polymer film coating is achieved by a combination of chemisorption and precipitation reactions on the electrode surface to cover more surface are of the electrode itself. It can result in the electrode having many layers of the chemical modifier on the electrode. This process can be broken down even further into these subcategories: i.Dip Coating

Here the conductor film is submerged in a solution for enough time so that the film formation of the electrode can form on the electrode.

ii.Solvent Evaporation

In solvent evaporation a drop of the solution of which the electrode is being coated with is put on the surface of the electrode and allowed to evaporate leaving the modified electrode with a trace of where the solution was covered. With this process one can immediately see where the polymer being applied has covered in the electrode.

iii.Spin Coating

In this process the electrode is being rotated while the solution is being applied. The excess solution runs off and this is repeated until the right amount of layers is acquired.

iv. Electrochemical Deposition

Also called redox deposition, electrochemical deposition is when a solvent is either reduced or oxidized to a state that is less soluble making it a permanent layer on the electrode.

v.Electrochemical Polymerization

This process involve a reduction-oxidation reaction where a polymer is formed on the surface of the electrode. With this process multiple layers are prevented from occurring because the film is in a more stable oxidation state. The layer merged onto the electrode has lower level of reactivity.

vi.Radio Frequency Polymerization

This method of modifying the conductor involves vaporizing the solution then exposing them to a radio frequency so that they may attach to the conductor. This process can cause chemical damage producing random and unknown alterations to the new electrode.

vii.Cross-Linking

Here the film is bonded to the electrode so that the electrode takes on properties of the film such as stability.

Applications
Chemically modified electrodes are now being used for a range of applications such as:

1.Biosensors

2.Electrochrmic Displays

3.Batteries

4.Corrosion Prevention

5.Molecular Electronics