JPS58200157A - Oxygen sensor - Google Patents

Abstract

PURPOSE:To obtain a high performance sensor which operates stably against changes in the O2 concentration with a large electromotive force and a high response speed by employing a porous conductor containing a polycyclo organic complex of transmission metal for a positive pole of an oxygen sensor. CONSTITUTION:To obtain a positive pole 4 of an oxygen sensor 1, transmission metal such as Ni, Co, Fe and Cu, a poriphin compound such as phthalocyanine and an aromatic polycyclo organic complex such as porphyrin are mixed into a teflon emulsion with carbon black, activated charcoal and the like and dried as a sheet. Then, this sheet 4b is joined under pressure on one side of a support collector 4a made of metal steel employing Ni, Ti or the like and heated to make a porous electrode 4. This electrode 4 is arranged on the side of a gas intake port 6 of a container 5 of a sensor 1 and an electrolytic layer 3 made of KOH, KC or the like between the electrode and a negative electrode 2 of Zn or the like to obtain a battery-operated oxygen sensor 1. This simplifies the measuring system usable without flowing of current thereby providing a sensor usable at the normal temperature free from heat generation of and deterioration in the element.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oxygen sensor used for measuring oxygen concentration in the environment at room temperature.

Detecting the oxygen concentration in the atmosphere and connecting it to alarm devices and other interlocking devices to prevent oxygen deficiency in caves and underground passages.
It is becoming more important as underground work increases. The oxygen sensor used for this oxygen sensitivity detection is galvanic #I
You can form an i-cell with the positive electrode of the porous electrode in contact with the gas to be measured, or form an 11-electrolyte cell with one electrode connected to the base metal partial pressure (generally, oxygen in the air in the atmosphere). partial pressure), the other electrode is brought into contact with the gas to be measured, and the resulting electromotive force or current change rtI11 is determined. There is a method to determine the change in electrical resistance (ti1).In addition, there is also a method that uses fluorescence quenching due to oxygen partial pressure.
Porous electrode containing silver etc., Zn for negative electrode.

MgQlt# is there. However, in the case of a dying electrolyte battery type, Zr and C Hatake0. When a porous conductor such as O8 is combined with a porous metal such as platinum or gold, pyrene is used.
Silicon Exhibition #111! However, among these materials in the prior art, noble metals such as platinum, gold, and silver are expensive, and the monolithic electrolyte does not operate under occlusion.

Oxide semiconductor materials have the disadvantage that the change in conductivity with respect to the base conductivity is small and that they are lost in the fluctuations of the base resistance, and that recovery is not quick. Sent has a poor response to oxygen partial pressure and lacks long-term stability, making it far from practical.

The present invention was made in view of the current situation, and
By using a porous conductor containing 4iT as an electrode, it is inexpensive, has a large electromotive force against changes in oxygen concentration, has a fast response, and is stable over a long period of time, resulting in high performance and high reliability. The purpose is to provide basic information.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

The 1st g1ll indicates -H of the oxygen center t of the present invention, and the symbol 1 in the figure is the forged steel 7 center t according to the present invention.

This oxygen sensor L has a negative electrode S made of a conductor such as metal,
An electrolyte layer 8 and a positive electrode 4 made of a porous conductor such as a transition metal organic complex are formed in close contact with each other in a layered manner. Electrolyte layer8. Kenso Ryuun 11, which consists of a positive pole number, is housed in Yong IIs. And Yong 4!
16 facing the positive electrode 8, there is a
Gas intake hole 6.6 for contacting the positive electrode 8 of 1.
is provided◎5WIJI111f't, 8
It is a lead wire consisting of a positive electrode 4 and a negative electrode s&:m. The above-mentioned correct 114 *The solute layer and the electrode 2 contain monooxygen, and also constitute a metal air layer battery that utilizes the reduction reaction of oxygen gas.

As shown in FIG. 2, the positive electrode number made of the porous conductor containing the j1 transfer metal iron body is, for example, the Fnal type. Titanium,
A support current collector 4 made of gold IIm steel such as silver, and a transmissive force 111,1 fixed on one surface of this support current collector 4a.
Below the porous electrode material c containing an organic complex, the porous jl['I
It is abbreviated as IIIi material. ) 4b, and is arranged so that the porous electrode material 4b is in contact with the electrolyte layer 8 and the support current collector 6 is in contact with the gas to be measured. A water-based binder such as Teflon (trademark) is added to 11 carbon bodies such as powdered carbon, graphic activated carbon, and acetylene planta, and to this, transition metals such as iron, nitsinal, copal), #, and manganese, and porphine such as 7-talocyanine are added. A complex with an aromatic long lI4 organic compound such as a gripping compound or porphyrin, and a transition metal organic complex such as a metal 7t1 cyanine, dianocobalamin, or hemodapin are added to form a sheet-shaped porous electrode material 4bt.
The porous electrode material 4b is bonded to the metal mesh of the supporting current collector 4m, or the carbon powder is mixed with a water-repellent binder and the powder is pressed together with the gold 4111 mesh to form a film. A method in which the above-mentioned complex is vapor-deposited on a metal mesh, a method in which a mixed powder consisting of a carbon powder heavy binder and a complex is pressurized and integrated with a metal mesh, or a porous metal plate is prepared in place of the metal mesh. It can be manufactured by coating this with carbon powder and Teflon, and further vapor-depositing a complex thereon.Then, the above-mentioned carbon powder and acetylene black.

Carbon materials such as Ketjenblack 10 have many reaction points where electrode reactions occur, promote porosity to facilitate the inclusion of catalysts to suppress activation, and at the same time reduce the number of electrons accompanying reactions. Sufficient conductivity toy for easy movement
・Porous metals are also effective as constituent materials for porous conductors, but when using this material, the metal itself dissolves in the electrolyte. In order to prevent a reaction different from the oxygen reduction reaction from occurring, it is necessary to protect the porous metal surface using tjj-bon spray or the like. − In order to prevent the electrolyte from leaking from the pores of the porous conductors, these porous conductors are coated with Teff haze powder,
↑Add water-stiffening agents such as adding 7W emulsion carbonate, pre-coating the surface with 7m spray, etc., or pasting a porous Teflon sheet on one side of the electrode facing the gas stream.
It also needs to be waterproofed. ! ! In addition, in order to extend the life of the positive electrode made of a porous conductor, a porous sheet made of a water-repellent material may be crimped onto the fi1m in contact with the gas to be measured, or a water repellant may be sprayed onto the material.

Furthermore, zinc is used as a material for the above-mentioned negative mst configuration.

Alt-Um, Madamushium, Shirogane! or an alloy thereof is used, and the electrolyte layer 8 is dωH.

Alkaline electrolytes such as NaOH, neutral electrolytes such as NaCj, KeI, acidic electrolytes such as phosphoric acid, liquid and colloidal liquid electrolytes with addition of corrosion inhibitors and precipitating flocculants, and solid electrolytes such as plastic ionic conductors. etc. are used.◎ In such an oxygen center t1 of the present invention, positive lll
The 11-transfer metal organic complex constituting the porous conductor of lA4 acts as an effective reduction catalyst for oxygen gas and exhibits excellent properties.In other words, the above complex adsorbs oxygen gas easily, The central metal contained in the complex can easily transfer electrons to the oxidized element by the surrounding organic compound ligands having a constant of 1I4, and the electron energy of the central metal can be easily transferred. Because the unit is close to one unit of energy of an oxygen molecule, in iron lids, cyanine, etc., oxygen reduction reaction 1 is the most efficient oxygen-electron reaction (for example,
1 Doni force Q in the layer liquid "C'410. +JH!0 +4C
e-→4IOH-)ti1! [In addition, the response of the potential change to the change in activity is also quick. On the other hand, in cobalt-7thalocyanine, cyanocobalacene, and niranalphthalocyanine peaks, the λ-electron reaction (M
For example, in an alkaline electrolyte, 0. +H! 0+λC-→O
H''-+ HO*-) becomes dominant, but these complexes on the carbon powder have a high resolution of intermediates, and the value of the potential change relative to T with respect to the oxygen concentration change is large and the response is quick.

Furthermore, since the oxygen sensor according to the present invention can be used without passing current, the measurement system can be simplified, such as not requiring a constant current source, and heat generation of the element due to current flow can be avoided. It has a long life without deterioration. In addition, since the oxygen sensor of the present invention measures the open circuit voltage as it is, it can be used without harsh electrolyte conditions, and has the major advantage of being able to use not only liquid electrolytes but also gel and solid electrolytes. It has the characteristic t1f.

Hereinafter, the present invention will be explained in a non-conventional manner by showing examples, but the present invention is not limited to these embodiments in any way.

Implementation Hi Carbon powder (passed 200 meshes), Aryu Chiren Black Co V, Ketchen/-Tsuku 1 OJf and 2 g of iron 7 talocyanine were added to a fan emulsion (60% teflon-containing).
%) Mix well j7F and form into a sheet using a tube.

After drying in air for a few minutes, a nickel net (CJO mesh) was placed on one side and hot-pressed at a pressure of 100°/II for 30 minutes. Cool it in the air, cut it into a circular shape, and attach it to the gas to be measured side.
A battery-type oxygen sensor was constructed using latom as the electrolyte and zinc as the negative electrode.
The oxygen partial pressure dependence of the electrode potential (1, vs. saturated calomel electrode) was investigated under mixed gas. The results are shown in Figure 3.

In other words, Figure 83 shows the dependence of the electrode potential on the oxygen partial pressure of the positive electrode made of a porous conductor placed on the gas-to-be-measured side of the oxygen sensor in this implementation H. If 1.0 is -e at''/d, 1.
It shows the change in electrode potential when currents of CK) and -- are passed through.

According to JWJ, changes in electrode potential due to changes in oxygen gas partial pressure vary from 01 to I whisper when no current is applied.
The partial pressure changes up to os, the same below the saturated calomel electrode with T and -aO da 7mC) to -0024IV,
On the other hand, when the oxygen gas concentration is changed from 190% to /'S, it changes from -aO to -aO6, causing some hysteresis.
For changes in oxygen concentration between l and l, it is
o'iv 5-aotsv.

-atatv~-QO9tV, the large potential change remains stable regardless of the direction of change, and
The response is quick. 11 In addition, in this case, there was no temporal change in potential and it was stable for a long time. and mix, 10
After about 21 minutes, it is filtered with 0-filtered water, washed with water, and dried. This mixture contains Teflon emulsion.
0%) j79 was thoroughly mixed and a positive conductor made of a porous conductor was prepared in the same manner as in Example II#A row I.

Furthermore, the electrode potential (-) is set in the same manner as in the real IIh column 1.

The oxygen partial pressure dependence of the saturated calomel electrode was investigated.

The results are shown in Figure 3. That is, the lI# diagram is a graph showing the oxygen partial pressure dependence of the electrode potential of the positive electrode placed on the measured gas side of the oxygen concentration in this example. That fn QOOI”7
6d, QOl''Vol (D shows the change in electrode potential when a small current is passed.

According to the reference figure, the electric potential is 0. Concentrations from 1% to lO
It changes reversibly when it changes from 100- to
saturated calomel -1 or less) to -Q//Jv,
QOO/ m, y ノ and @-Q2112V or 6-Q/
7V *Q O/■ Sea - When energized, it takes a value in the range of -axis to 10210V. The change in potential corresponding to the change in single-element partial pressure was T quick, but the potential did not change over time and was stable for a long period of time ◎ Actual 1sH7 carbon powder (-〇〇 mesh passage > 109. Acetylene black Mix 209 and f70 flour, ili! Heat treatment was performed in a furnace at ℃ for 30 minutes, and this electrode material was vapor-deposited to contain iron 7#cyanine or cobalt 7#cyanine to form a positive electrode, and placed on the side of the gas to be measured to create an oxygen concentration.・Then, the dependence of the electrode potential (V, vs. saturated calomel electrode) on the partial pressure of the element was investigated in the same manner as on implementation day 1. This is a graph showing the dependence of the potential on the oxygen partial pressure when no current is applied. The curve m1le shows the potential change of the porous electrode on which cyanine is deposited on the iron cap, and the porous electrode on which cobalt-7 talocyanine is deposited. It shows: Oxygen concentration is 10O from tS
-, and then from 1oos to 1% blindness, the potential changes are respectively -
Ql! From JV (versus saturation force, the same applies hereinafter) -a
io4Iv, changed from -aiop to -ai reference 7v.
Although a slight hysteresis occurs, this value is quite small compared to the magnitude of the potential change due to oxygen partial pressure change.
No problem. On the other hand, in the case of iron fluoride #■cyanine, the potential becomes R between -〇〇〇JV and -QOI/V,
Does not cause hysteresis ◎ In both cases of iron and cobalt granite 7 talocyanine, the response of the electrode potential to changes in oxygen partial pressure is T
It was quick and stable over a long period of time, with no visible changes in electrode potential over time.

Implemented ginseng carbon powder (passed through λOO mesh) 09. ↑70n 1k
Mix 109 g of kl (passed through the jtO mesh) and t/7/g of cobalamin Q, place this in a disc-forming grip lid together with a Niranal mesh, and press with a pressure of 30I%'cII.
Thereafter, a porous electrode was prepared by heat treatment in a furnace at 300°C for 30 minutes, and an oxygen center was formed. And implementation M/
The dependence of the electrode potential (V, vs. saturated 2I Romel electrode) on oxygen partial pressure was investigated in the same manner.

FIG. 6 shows the oxygen partial pressure dependence of the electrode potential of the positive electrode in contact with the gas to be measured in the above-mentioned example when no current is applied.

According to Figure 6, when the oxygen partial pressure changes from /- to 100≦ and then from 1oos to 71, the change in electrode potential is from -Q/j6V (vs. saturated calomel electrode, the same applies hereinafter). -QII da v, -aii da V to -Ql!
At t7V, it is almost reversible. The electrode changed quickly in response to changes in oxygen partial pressure, and no temporal changes in electric potential were observed, indicating long-term stability. Implementation Mj Carbon powder (passed through -〇〇 mesh > *g, + The measured gas side was prepared in the same manner as the actual WaH/, except that 33 g of Tchen Black Sang, 2 g of hemoglobin, and 33 g of Teflon emulsion carbonate (containing 1% of Teflon) were mixed well, and the hot pressing time was 10 minutes. A positive electrode made of a porous conductor was fabricated.Then, an oxygen-containing tube was assembled in the same manner as in Example H7, and the dependence of the electrode potential (V, vs. saturated calomel electrode) on oxygen partial pressure was investigated.

FIG. 7 shows the dependence of the electrode potential on the oxygen partial pressure when the positive electrode in contact with the gas to be measured is not energized in the above-described implementation Mj.

#17 According to diagram, the oxygen partial pressure is from 7- to 1oos,
Next, when changing from 100% to 1, the electrode potential changes from -ai61v (versus saturation force mel electrode, the same applies hereafter) to -
It changes reversibly in the range up to aioov. The electrode potential changed quickly in response to changes in oxygen partial pressure, and the electrode potential did not change over time and was stable over a long period of time.

Implementation M6 Carbon powder (passed through 200 meshes) Dali, Ketjenblack 1104c and copper 7-cyanine or manganese-7 talocyanine λg were placed in concentrated sulfuric acid and mixed for 30 minutes. After dropping it into pure water of approximately λ, it is filtered, washed with water, and dried. Add ↑70 ml of emulsion to this mixture.
A positive electrode made of a porous conductor was prepared in the same manner as in the actual kHz/.Furthermore, the oxygen sensor was assembled and raised in the same manner as in the actual IM/, and the electrode potential (1, Figure 1 shows the oxygen partial pressure dependence of the electrode potential of the two porous positive electrodes placed in the oxygen sensor to be measured in this implementation. In the glove shown in FIG. 1, "A" indicates the case where manganese phthalate cyanine is contained, and "J" indicates the case where copper 7# cyanine is contained.

According to the In2 diagram, the electric potential changes from 7% to t
oos, conversely, lOO%tpbi's;:, barbaric*,
Manganese 7#Russian and copper phthalocyanine also change reversibly and in response to changes in oxygen partial pressure.In response to the above changes in oxygen partial pressure, manganese 7#Russian contains copper phthalocyanine. In the case - aoii vC vs. saturated calomel electrode,
The same applies below) to +aoosV, and in the case of copper cyanine content, it changes from 10llcoV to -QO71V (/J@-).These electrode potentials change over time when the forging volume partial pressure is constant. It remained stable for a long time without changing.
Carbon fine powder and Teflon were alternately sprayed on a 1-meter peeled 7-hole porous GIL product tuna board (specification table - Yari 7700'/, /) so that the weight ratio of the two was 5=3. After it has dried to some extent, it is pressed lightly to adjust the electrode thickness 8, and then heat treated at 100° C. for 30 minutes in an argon atmosphere. After cooling, it was taken out and cut into a circular shape with a diameter of JO to produce a porous electrode.

Iron phthalocyanine module or cobalt phthalocyanine is carefully deposited on one side of this porous niranal electrode to form a thin film to form a positive electrode, which is the 11th side facing the deposited fIt electrolyte.

The thus prepared positive electrode was assembled into an oxygen sensor as in Example 1, and the dependence of the electrode potential c vs. saturation power (conductor electrode) on oxygen partial pressure was investigated.

FIG. 9 is a graph showing the oxygen partial pressure dependence of the electrode potential of the positive electrode disposed in the gas-to-be-measured preparation of the oxygen sensor in implementation v47. is the iron phthalocyanine flA deposited positive.
, and L indicates the potential change of the positive electrode on which cobalt phthalocyanine is deposited.

According to Figure 9, the change in the equilibrium potential of the electrode due to the change in oxygen partial pressure is 0 when cobalt 7#cyanine is deposited.
．． Conversely, when the concentration changes from 1% to lOO≦, 10
When changing from 0- to ls, it has a drying hysteresis in the range from -(1/Il"l (versus saturation force ■ Nor electrode, hereinafter referred to as i4m) to -02 das v!!. There is no hysteresis at all in practical use as an electrode for corrugated iron sensors.On the other hand, in the case of evaporating iron 7# russian, the temperature ranges from 1016 V to 10222 N for a uniform 0.0 concentration change.
Hysteresis up to rt4!1. The potential changes T reversibly without any interruption.

In both cases, the potential changes in response to changes in oxygen partial pressure are rapid (,
Moreover, no temporal change in potential was observed at the same oxygen concentration, and the potential was stable for a long period of time.

Implementation [1 Carbon powder * (λOO mesh: L passing), acetylene black coli, Natsuchen black 1029 and iron phthalocyanine at the same time [Pour in concentrated sulfuric acid and stir for 30 minutes ◎ Then, add to about 2I pure water After removing, washing with water, dry. The obtained mixed powder and cyanobacterium aOda 2 and tjO- were stirred in water, and this was dropped into about 1,000 liters of acetone.

Mixed powder obtained by drying once and ↑7 Kan-e! Mix 33g of luzi (containing 60% F70) with a tube and roll it into a sheet. From this sheet, make a positive electrode made of porous conductor in the same manner as in M/. The positive electrode was assembled into an oxygen-containing tube as shown in Example 111M/, and the dependence of the electrode potential (vs. saturated calomel charge m) on oxygen partial pressure was investigated.The results are shown in Part 1oIIi!!l.

According to Figure 10, the change in the equilibrium potential of the electrode due to the change in oxygen partial pressure is ρ, from l to 100% concentration, then t
When changing from oos to 7%, it was in the range of -003V (against saturated calomel electrode, the same applies hereinafter) to -QO7JV ・Some hysteresis occurs, but there is no problem as an electrode for oxygen senna ・Mase JV The potential responds quickly to changes in partial pressure, and no temporal changes in electrode potential were observed at the same oxygen partial pressure, demonstrating the excellent characteristics of a highly sensitive, long-term stable electrode for an oxygen sensor.

As explained above, the oxygen sensor of the present invention has a positive electrode in contact with a gas to be measured containing various metals such as transition metals, cyanine, dianocobalamin, and hemoglobin.
◎Therefore, according to the oxygen-sensing tube of the present invention, the positive electrode made of the porous conductor can quickly respond to a 1 degree change in oxygen gas by T. It also provides a large potential change that can be used sufficiently, has long-term stability, and exhibits excellent 'F: characteristics.
This oxygen sensor quickly and reliably measures changes in the oxygen concentration in the gas being measured, is stable over a long period of time, has great reliability, and has high practical value.

[Brief explanation of the drawing]

Figure 117 shows a row of oxygen-sensing tubes of the present invention.
The IJ diagram and Figure 2 show the porous conductor used in the positive electrode of the oxygen sensor of the present invention. 1 is a T graph showing the relationship between the oxygen partial pressure and the electrode potential of this Jongdake sensor. l...Oxygen sensor, 8...Negative electrode, 8.
... Electrolyte layer, number ... Positive electrode, b...
... Soy sauce, 6... Gas intake hole. Source Nippon Telegraph and Telephone Public Corporation Figure 1 Figure 3 Figure 4 Figure 5 0*Ra ('4) Figure 6 Figure 7 Figure 8 Figure 9 Figure 11O Figure

Claims (1)

[Claims] a negative electrode; a positive electrode in contact with a gas to be measured containing oxygen;
In the oxygen sensor, which has an electrolyte layer provided between these two electrodes and detects the oxygen concentration in the gas to be measured by measuring the electromotive force between the two electrodes, the positive electrode contains a transition gold layer-rich organic complex. T
Porous conductor t#1 patented and tethered 7-pin 1゜