Metal oxide electrodes
First Claim
1. A metal oxide electrode sensitive to hydrogen ions comprising:
- a mixture of at least one insulating material having a density of binding sites sufficiently large to be sensitive to hydrogen ions, and at least one conductive metal oxide selected from the Group VIIIB metal oxides,wherein the size of the particles of conductive metal oxide in said mixture is sufficiently small as to not exhibit bulk conductive properties, thereby reducing the susceptibility of said mixture to redox interference, while the molar ratio of said conductive metal oxide to said insulating material is sufficiently large than the resistivity of said mixture is in the range of 1010 to 1014 ohm-cm, whereby the electrode, as a whole, has sufficient conductivity to operate in a Faradaic configuration.
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Abstract
An electrode for measuring the activity of ionic species. The electrode comprises a material which is chemically sensitive to at least one ionic species. The material comprises an insulating component and a conductive component of lower resistivity than the insulating component. The insulating component has a density of proton binding sites sufficiently large to be sensitive to the ionic species. The conductive component comprises particles, the size of which are sufficiently small to modify the bulk conductive properties such that the susceptibility of the particles to redox interference in the operation of the electrode is decreased, while maintaining sufficient conductivity to operate in Faradaic electrode configurations. Illustratively, the insulating component is tantalum oxide, zirconium oxide or aluminum oxide and the conductive component is iridium, platinum, ruthenium, palladium, rhodium or osmium oxide.
161 Citations
20 Claims
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1. A metal oxide electrode sensitive to hydrogen ions comprising:
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a mixture of at least one insulating material having a density of binding sites sufficiently large to be sensitive to hydrogen ions, and at least one conductive metal oxide selected from the Group VIIIB metal oxides, wherein the size of the particles of conductive metal oxide in said mixture is sufficiently small as to not exhibit bulk conductive properties, thereby reducing the susceptibility of said mixture to redox interference, while the molar ratio of said conductive metal oxide to said insulating material is sufficiently large than the resistivity of said mixture is in the range of 1010 to 1014 ohm-cm, whereby the electrode, as a whole, has sufficient conductivity to operate in a Faradaic configuration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An electrode for measuring pH comprising:
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a mixture of a first component which is conductive in bulk form, and a second component having a substantially greater resistivity in bulk form than that of said first component, said second component having a redox-interference-free surface response to hydrogen ions, said first component being present in said mixture in sufficiently small particle size so as to modify its bulk conductive properties enough that it does not affect the redox-interference-free surface response of said second component to hydrogen ions, wherein the molar ratio of said first component to said second component is sufficiently large that the resistivity of said mixture is in the range of 1010 to 1014 ohm-cm, whereby the electrode, as a whole, has sufficient conductivity to operate as a pH sensing electrode. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification