Electrochemical sensors
View Patent ↗An electrode for use in a electrochemical sensor comprises carbon modified with a chemically sensitive redox-active compound, excluding an electrode based on carbon having derivatized thereon two redox-active species wherein at least one of said species is selected from anthraquinone, phenanthrenequinone and N,N′-diphenyl-p-phenylenediamine (DPPD). The invention further provides a pH sensor comprising: a working electrode comprising carbon modified with a chemically sensitive redox active material; and a counter electrode, wherein the ratio of the surface area of the working electrode to the surface area of the counter electrode is from 1:10 to 10:1. Also provided is a pH sensor comprising: a working electrode comprising carbon modified with a chemically sensitive redox active material, and a counter electrode, wherein the area of the working electrode is from 500 μm 2 to 0.1 m 2 . The uses of these electrodes and sensors are also described.
1. A method for preparing an electrode for use in an electrochemical sensor, said method comprising
modifying unmodified graphite powder or unmodified multi-walled carbon nanotubes with a chemically sensitive redox active material to form a chemically sensitive redox derivatized carbon,
wherein the chemically sensitive redox active material is a chemically sensitive material selected from the group consisting of anthracenes, quinones, anthraquinones, and phenanthraquinones;
wherein the chemically sensitive redox derivatized carbon is stable over a period of greater than 1 month, and
wherein the step of modifying comprises one or more of the following methods:
a) derivatization via physical adsorption of the chemically sensitive redox active material; and
b) physical mixing with the chemically sensitive redox active material and a binder.
2. The method according to claim 1 , further comprising the step of applying the chemically sensitive redox derivatized carbon to a substrate.
3. The method according to claim 2 , wherein the step of applying comprises abrasively immobilising the composition on the surface of the substrate.
4. An electrode for use in an electrochemical sensor, said electrode comprising a chemically sensitive redox derivatized carbon produced from unmodified graphite powder or unmodified multi-walled carbon nanotubes, and a chemically sensitive redox-active compound,
wherein the chemically sensitive redox-active compound is a chemically sensitive material selected from the group consisting of anthracenes, quinones, anthraquinones, and phenanthraquinones;
wherein the chemically sensitive redox derivatized carbon is stable over a period of greater than 1 month, and
wherein the redox-active compound is either:
a) physically adsorbed to the graphite powder or multi-walled carbon nanotubes; or
b) bound to the graphite powder or multi-walled carbon nanotubes by physically mixing the chemically sensitive redox-active material and a binder.
5. The electrode according to claim 4 , wherein the chemically sensitive redox active compound is sensitive to the concentration of protons.
6. The electrode according to claim 4 , wherein the chemically sensitive redox active compound is physically adsorbed to the graphite powder or multi-walled carbon nanotubes.
7. An electrochemical sensor comprising an electrode as claimed in claim 4 .