CO gas sensor and method of using same
First Claim
1. A CO gas sensor for measuring CO concentration in an atmosphere containing CO and hydrogen gases, said sensor comprising:
- a detector including a detection electrode, a counter electrode and a solid electrolyte member sandwiched between said detection electrode and said counter electrode, wherein said detection electrode comprises a first electrochemically active catalyst carried on an electrically conductive porous body and forming a reaction layer thereon, said first catalyst having a density of 1 ng/cm2-100 μ
g/cm2 and a thickness of 0.3 nm-15 μ
m, and wherein said counter electrode comprises a second electrochemically active catalyst carried on an electrically conductive porous body;
means for contacting said detector with the atmosphere;
voltage application means for applying, between said detection electrode and said counter electrode while in contact with the atmosphere, a voltage in a wave form wherein the voltage continuously cycles between CO oxidation potential and CO adsorption potential and for thereby causing a response current to flow between said electrodes responsive to the applied voltage;
means for measuring the amount of response current; and
determination means for determining the CO concentration based on the measured amount of response current.
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Abstract
A CO gas sensor is equipped with a detecting unit in which a solid electrolyte membrane is held between a detection electrode and a counter electrode, and a voltage applying unit which applies voltage between the detection electrode and the counter electrode and changes the voltage. The detection electrode includes an electrochemically active first catalyst in an electrically conductive porous body, a reaction layer having a density of 1 ng/cm2-100 μg/cm2 and having a thickness of 0.3 nm-15 μm, and the counter electrode includes an electrochemically active second catalyst carried on an electrically conductive porous body.
26 Citations
18 Claims
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1. A CO gas sensor for measuring CO concentration in an atmosphere containing CO and hydrogen gases, said sensor comprising:
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a detector including a detection electrode, a counter electrode and a solid electrolyte member sandwiched between said detection electrode and said counter electrode, wherein said detection electrode comprises a first electrochemically active catalyst carried on an electrically conductive porous body and forming a reaction layer thereon, said first catalyst having a density of 1 ng/cm2-100 μ
g/cm2 and a thickness of 0.3 nm-15 μ
m, and wherein said counter electrode comprises a second electrochemically active catalyst carried on an electrically conductive porous body;
means for contacting said detector with the atmosphere;
voltage application means for applying, between said detection electrode and said counter electrode while in contact with the atmosphere, a voltage in a wave form wherein the voltage continuously cycles between CO oxidation potential and CO adsorption potential and for thereby causing a response current to flow between said electrodes responsive to the applied voltage;
means for measuring the amount of response current; and
determination means for determining the CO concentration based on the measured amount of response current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A CO gas sensor for measuring CO concentration in an atmosphere containing CO and hydrogen gases, said sensor comprising:
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a detector including a detection electrode, a counter electrode and a solid electrolyte member sandwiched between said detection electrode and said counter electrode;
means for contacting said detector with the atmosphere;
voltage application means for applying, between said detection electrode and said counter electrode while in contact with the atmosphere, a voltage in a wave form wherein the voltage continuously cycles between CO oxidation potential and CO adsorption potential and for thereby causing a response current to flow between said electrodes responsive to the applied voltage, said response current being 0.001 mA/cm2 to 1 A/cm2 at said CO adsorption potential;
means for measuring the amount of response current; and
determination means for determining the CO concentration based on the measured amount of response current. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A CO gas sensor for measuring CO concentration in an atmosphere containing CO and hydrogen gases, said sensor comprising:
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a detector including a detection electrode, a counter electrode and a solid electrolyte member sandwiched between said detection electrode and said counter electrode, wherein the detection electrode comprises a porous body which is electrochemically inactive and has electrical conductivity, and a reaction layer which is formed on the body and contains an electrochemically active first material, wherein density of the reaction layer is 1 ng/cm2-100 μ
g/cm2 and thickness of the reaction layer is 0.3 nm-15 μ
m;
means for contacting said detector with the atmosphere;
voltage application means for applying, between said detection electrode and said counter electrode while in contact with the atmosphere, a voltage in a wave form wherein the voltage continuously cycles between CO oxidation potential and CO adsorption potential and for thereby causing a response current to flow between said electrodes responsive to the applied voltage;
means for measuring the amount of response current; and
determination means for determining the CO concentration based on the measured amount of response current.
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18. A method for measuring CO concentration in an atmosphere containing CO and hydrogen gases, said method comprising:
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providing a detector including a detection electrode, a counter electrode and a solid electrolyte membrane sandwiched between said detection electrode and said counter electrode;
contacting the detector with the atmosphere;
applying a voltage between said electrodes while in contact with the atmosphere, said voltage continuously alternating between a CO oxidation potential upper limit and a CO adsorption potential lower limit, thereby causing a response current to flow between the electrodes responsive to the applied voltage;
determining the rate of current decrease in transition from the CO oxidation potential to the CO adsorption potential; and
determining CO concentration based on the determined rate of current decrease.
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Specification