Electrode activity measuring device and method

Abstract

The invention provides an electrode activity measuring device and method. The device comprises a first measuring unit, a second measuring unit and a valve, the first measuring unit comprises a first shell, a first electrolytic tank positioned in the first shell and a diffusion channel; one end of the first electrolytic tank is used for mounting a to-be-detected electrode, one end of the diffusion channel is connected with the first electrolytic tank, and the other end penetrates through the first shell and is used for enabling gas with known concentration to enter the first electrolytic tank; the second measuring unit is adjacent to the first measuring unit and comprises a second shell, a second electrolytic tank and a working electrode, the second electrolytic tank and the working electrode are located in the second shell, and the working electrode is located on one side of the second electrolytic tank; the valve is arranged between the first shell and the second shell. The gas with the known concentration is controlled to enter the first measuring unit or enter the first measuring unit and the second measuring unit by opening and closing the valve, the activity of the diffusion electrode for the gas sensor is rapidly measured by two times of detection, and the research and development and production quality control efficiency of the gas sensor is improved.

Description

Technical Field

[0001] The present application relates to the field of chemical technology, and in particular to an electrode activity measurement device and method. Background Art

[0002] In order to improve the response sensitivity, reduce the detection limit and improve the stability of controlled potential current type electrochemical gas sensors, catalytic materials with high activity to the target gas are generally used and prepared into gas diffusion electrodes. The electrode material, electrode microstructure, electrode preparation process, electrolyte composition, etc. have a great influence on the electrode activity.

[0003] During the sensor development process, the performance of the sensor electrode needs to be systematically evaluated, among which the measurement of its catalytic activity is a very important indicator. Selecting a highly active catalyst helps to improve the stability of the sensor and reduce the detection limit. In addition, during the production process, activity testing of different batches of electrodes is also an important quality control method. Therefore, an indicator and measurement method for evaluating electrode activity are needed.

[0004] There is currently no good direct measurement method for the activity of gas diffusion electrodes used in gas sensors. The usual practice is to assemble the electrodes into finished sensors, and then conduct a systematic evaluation of the sensor performance, especially the measurement and analysis of its long-term stability, and judge the size of the electrode catalyst activity based on this; for sensors whose sensitivity is affected by the mixed control of gas diffusion and electrode reaction kinetics, changes in electrode activity have a certain impact on the sensitivity of the sensor. The fluctuation of electrode activity is mainly affected by environmental factors, the electrode's own microstructure, changes in hydrophilicity and hydrophobicity, etc. This can be evaluated and analyzed through sensor stability and reliability tests, but it is relatively time-consuming. Summary of the invention

[0005] The purpose of this application is to provide an electrode activity measurement device and method, which can quickly measure the electrode activity of a diffusion electrode and improve the efficiency of gas sensor research and development and production quality control.

[0006] The electrode activity measuring device comprises:

[0007] The first measuring unit comprises: a first shell, a first electrolytic cell and a diffusion channel; one end of the first electrolytic cell is used to install the electrode to be measured, and is located in the first shell; one end of the diffusion channel is connected to the first electrolytic cell, and the other end passes through the first shell, and is used to allow the gas of known concentration to enter the first electrolytic cell;

[0008] A second measuring unit, the second measuring unit is arranged adjacent to the first measuring unit; the second measuring unit comprises: a second shell, a second electrolytic cell and a working electrode; the second electrolytic cell is located in the second shell; the working electrode is located at one side of the second electrolytic cell;

[0009] The valve is arranged between the first shell and the second shell, and the opening and closing of the valve is used to control whether the gas with known concentration enters the second measuring unit from the first measuring unit.

[0010] In one example, the first electrolytic cell comprises:

[0011] a first reference electrode;

[0012] The first pair of electrodes, the first reference electrode and the first pair of electrodes are arranged at intervals;

[0013] The first electrolyte is located in the first shell, and one end of the first electrolyte is attached to the first reference electrode and the first counter electrode.

[0014] In one example, the second electrolytic cell comprises:

[0015] a second reference electrode;

[0016] The second pair of electrodes, the second reference electrode and the second pair of electrodes are spaced apart;

[0017] The second electrolyte is located in the second shell, one end of the second electrolyte is attached to the working electrode, and the other end is attached to the second reference electrode and the second counter electrode.

[0018] In one example, the first detection unit further includes: a first buffer chamber, the first buffer chamber is located in the first housing and is connected to the diffusion channel and one end of the valve respectively;

[0019] The second detection unit also includes: a second buffer chamber, which is located in the second shell, covers the working electrode, and is connected to the other end of the valve.

[0020] In one example, the first housing includes:

[0021] A bottom shell, wherein the first electrolytic cell is located in the bottom shell;

[0022] The upper cover and the diffusion channel are located inside the upper cover, and the upper cover and the bottom shell are detachably connected.

[0023] In one example, the electrode activity measuring device further comprises:

[0024] The gas channel is connected with the diffusion channel and is used for passing a gas with a known concentration.

[0025] In one example, the first detection unit further includes: a gas permeable membrane, wherein the gas permeable membrane is located between the diffusion channel and the first buffer chamber.

[0026] In one example, the electrode activity measurement device is used to perform measurement, and the method includes:

[0027] Assembling the electrode to be measured into the first measuring unit, and connecting the measuring circuit so that both the first measuring unit and the second measuring unit are in a balanced working state;

[0028] Close the valve, pass a gas of known concentration, measure it through the first measuring unit alone, and obtain a first steady-state response current of the gas of known concentration measured by the first measuring unit;

[0029] Open the valve, and the first measuring unit and the second measuring unit jointly perform measurement to obtain a second steady-state response current and a third steady-state response current of the gas with a known concentration measured by the first measuring unit and the second measuring unit;

[0030] The activity of the electrode to be tested is determined according to the known gas concentration and the first steady-state response current, the second steady-state response current, and the third steady-state response current.

[0031] In one example, the activity of the electrode to be tested is determined according to the known gas concentration and the first steady-state response current, the second steady-state response current, and the third steady-state response current, using the following formula:

[0032] R 15 =[((I 15b +I 33b )-I 15a ) / I 15a I 15b ]C1

[0033] Among them, R 15 is the activity of the electrode to be tested, C1 is the known gas concentration, I 15a is the first steady-state response current, I 15b is the second steady-state response current, I 33b is the third steady-state response current.

[0034] In one example, the valve is opened, and the first measuring unit and the second measuring unit perform measurements together to obtain the second steady-state response current and the third steady-state response current of the gas with known concentration measured by the first measuring unit; including:

[0035] Controlling the gas with known concentration to pass through the diffusion channel and then enter the first measuring unit;

[0036] A portion of the gas with known concentration reacts with the electrode to be tested to obtain a second steady-state response current;

[0037] Another portion of the gas with known concentration enters the second measuring unit through the valve and reacts with the working electrode to obtain a third steady-state response current.

[0038] The beneficial effects of this application compared with the prior art are:

[0039] The present application uses a first measuring unit, a second measuring unit and an openable and closable valve to quickly test the activity of the electrode to be tested, thereby quickly obtaining the activity of the electrode to be tested, thereby improving the efficiency of gas sensor research and development and production quality control. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 A schematic diagram of an electrode activity measurement device provided in one embodiment of the present application;

[0042] Figure 2 A schematic diagram of the electrode activity measurement principle provided in one embodiment of the present application;

[0043] Figure 3 for Figure 1 A schematic diagram of an equivalent circuit corresponding to the electrode activity measuring device provided in the corresponding embodiment;

[0044] Figure 4 A schematic diagram of the steps of a method for measuring electrode activity provided in one embodiment of the present application;

[0045] Figure 5 A detailed step diagram of step S430 provided in an embodiment of the present application.

[0046] The above drawings include the following reference numerals:

[0047] 1-first measuring unit; 10-first shell; 11-first electrolytic cell; 12-diffusion channel; 13-first buffer chamber; 14-gas permeable membrane; 15-electrode to be measured; 101-bottom shell; 102-upper cover; 111-first electrolyte; 112-first reference electrode; 113-first counter electrode; 2-valve; 3-second measuring unit; 31-second shell; 32-second electrolytic cell; 33-working electrode; 34-second buffer chamber; 323-second electrolyte; 324-second reference electrode; 325-second counter electrode; 4-gas channel. DETAILED DESCRIPTION

[0048] The terms “first”, “second”, “third”, etc. are only used for distinguishing descriptions and do not indicate the order of arrangement, nor can they be understood as indicating or implying relative importance.

[0049] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0050] In the description of the present application, it should be noted that the terms "inside", "outside", "left", "right", "up", "down", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the products of the present application are usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0051] In the description of this application, unless otherwise clearly specified and limited, the terms "set", "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0052] Figure 1 A schematic diagram of an electrode activity measurement device provided in an embodiment of the present application, such as Figure 1 As shown, the electrode activity measuring device includes: a first measuring unit 1, a second measuring unit 3 and a valve 2. The first measuring unit 1 includes: a first shell 10, a first electrolytic cell 11 and a diffusion channel 12; the first electrolytic cell 11 is located in the first shell 10, one end of the diffusion channel 12 is connected to the first electrolytic cell 11, and the other end passes through the first shell 10, which is used to allow a gas of known concentration to enter the first electrolytic cell 11; wherein one end of the first electrolytic cell 11 is used to install the electrode to be measured 15. The second measuring unit 3 is arranged adjacent to the first measuring unit 1; the second measuring unit 3 includes: a second shell 31, a second electrolytic cell 32 and a working electrode 33; the second electrolytic cell 32 is located in the second shell 31; the working electrode 33 is located on one side of the second electrolytic cell 32; the valve 2 is arranged between the first shell 10 and the second shell 31, and the opening and closing of the valve 2 controls whether the gas of known concentration enters the second measuring unit 3 from the first measuring unit 1. When the valve 2 is opened, the gas with known concentration enters the second measuring unit 3 from the first measuring unit 1 . When the valve 2 is closed, the gas with known concentration only enters the first measuring unit 1 and does not enter the second measuring unit 3 .

[0053] In the present application, the valve 2 is first closed, a gas of known concentration is introduced into the first measuring unit 1 for measurement, and then the valve 2 is opened to introduce a gas of known concentration into the first measuring unit 1 and the second measuring unit 3 for measurement. The activity of the electrode to be measured 15 is calculated using the response current obtained from the two measurements and the known gas concentration (the specific calculation process is detailed below and will not be repeated here). The device can quickly measure the electrode activity of the electrode to be measured 15, thereby improving the efficiency of gas sensor research and development and production quality control.

[0054] In one example, if Figure 1 As shown, the electrode activity measuring device also includes: a gas channel 4, which is connected to the diffusion channel 12 and is used to pass a gas of known concentration; wherein the first shell 10 includes: a bottom shell 101 and an upper cover 102, and the first electrolytic cell 11 is located in the bottom shell 101; the diffusion channel 12 is located in the upper cover 102, and the upper cover 102 is detachably connected to the bottom shell 101, and the electrode 15 to be measured is placed in the first electrolytic cell 11 by removing the upper cover 102.

[0055] In one embodiment, the first electrolytic cell 11 includes: a first electrolyte 111, a first reference electrode 112 and a first counter electrode 113; the first reference electrode 112 and the first counter electrode 113 are arranged at intervals, the first reference electrode 112 is used to provide a reference potential for the electrode to be measured 15, and the first counter electrode 113 is used to ensure that current flows through the first electrolyte 111; the first electrolyte 111 is located in the first shell 10, one end of which is in contact with the first reference electrode 112 and the first counter electrode 113, and the other end is in contact with the electrode to be measured 15.

[0056] In another embodiment, the second electrolytic cell 32 includes: a second electrolyte 323, a second reference electrode 324 and a second pair of electrodes 325; the second reference electrode 324 and the second pair of electrodes 325 are arranged at intervals, the second reference electrode 324 is used to provide a reference potential for the electrode to be measured 15, and the second pair of electrodes 325 is used to ensure that the current flows through the second electrolyte 323; the second electrolyte 323 is located in the second shell 31, one end is in contact with the second reference electrode 324 and the second pair of electrodes 325, and the other end is in contact with the working electrode 33.

[0057] In one embodiment, the first detection unit 1 further includes: a first buffer chamber 13 and a gas permeable membrane 14, the first buffer chamber 13 is located in the first shell 10, and is connected to the diffusion channel 12 and one end of the valve 2 respectively, and is used to isolate the first electrolytic cell 11 from the external environment, thereby improving the measurement accuracy of the first detection unit; the gas permeable membrane 14 is a diffusion hole or a gas permeable membrane, and is located between the diffusion channel 12 and the first buffer chamber 13, and is used to adjust the rate at which the gas of known concentration enters the first buffer chamber 13 from the diffusion channel 12. The second detection unit 3 further includes: a second buffer chamber 34, the second buffer chamber 34 is located in the second shell 31, covers the working electrode 33, and is connected to the other end of the valve 2; it is used to isolate the second electrolytic cell 32 and the working electrode 33 from the external environment, thereby improving the measurement accuracy of the second detection unit. The valve 2 can be used to control whether the first buffer chamber 13 and the second buffer chamber 34 are unobstructed, that is, whether the gas of known concentration enters the second measurement unit 3.

[0058] The embodiments of the present application also provide a method for measuring electrode activity, which can be performed by the electrode activity measuring device described in the above embodiments. Figure 2 A schematic diagram of the electrode activity measurement principle provided in an embodiment of the present application is shown in FIG. Figure 2 As shown, this equivalent circuit is the equivalent circuit of the electrode reaction of the electrochemical gas sensor, where R g is the gas mass transfer impedance, C d is the double layer capacitance of the electrode, R r is the electrode reaction kinetic impedance (used to characterize electrode activity); where R r Corresponding to the electrode reaction kinetics process, it is related to the catalyst activity. Changes in catalyst activity will lead to R r The greater the electrode activity, the greater the R r Therefore, by measuring R r The change in is used to determine the size of the electrode activity.

[0059] Further, by Figure 2 The electrode equivalent circuit shown in the figure is analyzed, and the steady-state response current of the sensor satisfies formula (1) (the influence of Cd on the measurement can be ignored in steady-state measurement):

[0060] I = kC = C / (R g +R r ); (1)

[0061] Where I is the response current, k is the response sensitivity, R g is the gas diffusion resistance, R r is the electrode reaction impedance, and C is the gas concentration. Therefore, based on the above principle, R r (reflecting electrode activity) for measurement.

[0062] Figure 3 for Figure 1 The equivalent circuit diagram corresponding to the electrode activity measurement device provided in the corresponding embodiment is based on Figure 1-3 As shown, R 12 is the impedance of the diffusion channel 12, R 15 is the reaction kinetic impedance of the electrode 15 to be tested, R 33 is the reaction dynamics impedance of the second measuring unit 3 , and R2 is the impedance of the valve 2 .

[0063] According to the equivalent circuit:

[0064] R g =R 12 ; (2)

[0065]

[0066] Among them, R 12 is the gas diffusion resistance, R 15 is the reaction impedance of the electrode 15 to be tested, R 2+33 It is the sum of the impedances of the working electrode 33 and the valve 2.

[0067] Figure 4 A schematic diagram of the steps of an electrode activity measurement method provided in an embodiment of the present application, the electrode activity measurement method comprises the following steps:

[0068] Step S410: Assemble the electrode 15 to be measured into the first measuring unit 1, and connect the measuring circuit so that the first measuring unit 1 and the second measuring unit 3 are both in a balanced working state;

[0069] Step S420: Close the valve 2, pass the gas of known concentration, measure it through the first measuring unit 1 alone, and obtain the first steady-state response current of the gas of known concentration measured by the first measuring unit 1; in the equivalent circuit corresponding to the electrode activity measuring device, the gas of known concentration enters the first measuring unit 1 and reacts with the electrode to be measured 15, so that formula (4) is satisfied:

[0070] R 12 + R 15 = C1 / I 15a ; (4)

[0071] Among them, I 15a is the first steady-state response current, C1 is the known gas concentration, R 12 is the gas diffusion resistance, R 15 is the reaction impedance of the electrode 15 to be measured.

[0072] Step S430: Open the valve 2, and the first measuring unit 1 and the second measuring unit 3 perform measurement together to obtain the second steady-state response current and the third steady-state response current of the gas with known concentration measured by the first measuring unit 1 and the second measuring unit 3;

[0073] Furthermore, Figure 5 A detailed step diagram of step S430 provided in an embodiment of the present application is shown in FIG. Figure 5 As shown, the above step S430 specifically includes:

[0074] Step S431: Control the gas with known concentration to pass through the diffusion channel 12 and then enter the first measurement unit 1;

[0075] Step S432: a portion of the gas with known concentration reacts with the electrode to be tested 15 to obtain a second steady-state response current;

[0076] Step S433: another part of the gas with known concentration enters the second measuring unit 3 through the valve 2, and reacts with the working electrode 33 to obtain a third steady-state response current.

[0077] Therefore, when valve 2 is opened, formula (5) is finally satisfied:

[0078] R 12 + R 15 R 2+33 / ( R 15 +R 2+33 )= C / (I 15b +I 33b ); (5)

[0079] Among them, I 150b is the second steady-state response current, I 33b is the third steady-state response current, C1 is the known gas concentration, R 12 is the gas diffusion resistance, R 15 is the reaction impedance of the electrode 15 to be tested, R 2+33 It is the sum of the impedances of the working electrode 33 and the valve 2.

[0080] Step S440: determining the activity of the electrode to be tested 15 according to the known gas concentration and the first steady-state response current, the second steady-state response current, and the third steady-state response current.

[0081] The measurement current and impedance distribution of the first measurement unit 1 and the second measurement unit 3 satisfy the relationship:

[0082] I 15b / I 33b = R 2+33 / R 15 ; (6)

[0083] Among them, I 15b is the second steady-state response current, I 230b is the third steady-state response current, R 15 is the reaction impedance of the electrode 15 to be tested, R 2+33 It is the sum of the impedances of the working electrode 33 and the valve 2.

[0084] Therefore, by combining formulas (4), (5), and (6), we can calculate R 15 :

[0085] R 15 = [((I 15b + I 33b )-I 15a ) / I 15a I 15b ]C1; (7)

[0086] Among them, R 15 is the reaction impedance of the electrode 15 to be tested (used to characterize the activity of the electrode 15 to be tested), C1 is the known gas concentration, I 15a is the first steady-state response current, I 15b is the second steady-state response current, I 33b is the third steady-state response current.

[0087] The present application controls the gas of known concentration to enter the first measuring unit 1 through the gas channel 4 to react with the electrode to be measured 15 by closing the valve 2, and then opens the valve 2 to control part of the gas of known concentration to enter the first measuring unit 1 to react with the electrode to be measured 15, and part of the gas to enter the second measuring unit 3 to react with the working electrode 33. The activity of the electrode to be measured 15 is calculated using the first steady-state response current, the second steady-state response current, the third steady-state response current obtained from the two measurements and the known gas concentration. The device and method can quickly measure the electrode activity of the electrode to be measured 15, thereby improving the efficiency of gas sensor research and development and production quality control.

[0088] It should be noted that, in the absence of conflict, the features in the embodiments of the present application can be combined with each other. The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An electrode activity measuring device, characterized in that: include: A first measuring unit, the first measuring unit comprising: a first shell, a first electrolytic cell and a diffusion channel; one end of the first electrolytic cell is used to install the electrode to be measured, and is located in the first shell; one end of the diffusion channel is connected to the first electrolytic cell, and the other end passes through the first shell, so that the gas of known concentration enters the first electrolytic cell; A second measuring unit, the second measuring unit is arranged adjacent to the first measuring unit; the second measuring unit comprises: a second shell, a second electrolytic cell and a working electrode; the second electrolytic cell is located in the second shell; the working electrode is located at one side of the second electrolytic cell; A valve is provided between the first shell and the second shell, and the opening and closing of the valve is used to control whether the gas with known concentration enters the second measuring unit from the first measuring unit.

2. The electrode activity measuring device according to claim 1, characterized in that: The first electrolytic cell comprises: a first reference electrode; a first pair of electrodes, wherein the first reference electrode and the first pair of electrodes are spaced apart from each other; A first electrolyte is located in the first shell, and one end of the first electrolyte is attached to the first reference electrode and the first pair of electrodes.

3. The electrode activity measuring device according to claim 1, characterized in that: The second electrolytic cell comprises: a second reference electrode; a second pair of electrodes, wherein the second reference electrode and the second pair of electrodes are spaced apart from each other; A second electrolyte is located in the second shell, one end of the second electrolyte is attached to the working electrode, and the other end of the second electrolyte is attached to the second reference electrode and the second counter electrode.

4. The electrode activity measuring device according to claim 1, characterized in that: The first detection unit further includes: a first buffer chamber, which is located in the first housing and is connected to the diffusion channel and one end of the valve respectively; The second detection unit further includes: a second buffer chamber, which is located in the second shell, covers the working electrode, and is connected to the other end of the valve.

5. The electrode activity measuring device according to claim 1, characterized in that: The first housing comprises: A bottom shell, wherein the first electrolytic cell is located in the bottom shell; An upper cover, wherein the diffusion channel is located inside the upper cover, and the upper cover is detachably connected to the bottom shell.

6. The electrode activity measuring device according to claim 1, characterized in that: The electrode activity measuring device also includes: A gas channel is communicated with the diffusion channel and is used for passing a gas with a known concentration.

7. The electrode activity measuring device according to claim 4, characterized in that: The first detection unit further includes: a gas permeable membrane, and the gas permeable membrane is located between the diffusion channel and the first buffer chamber.

8. A method for measuring electrode activity, characterized in that: The electrode activity measuring device according to any one of claims 1 to 7 is used for measurement, and the method comprises: Assembling the electrode to be measured into the first measuring unit, and connecting the measuring circuit so that the first measuring unit and the second measuring unit are both in a balanced working state; Close the valve, pass a gas of known concentration, measure it through the first measuring unit alone, and obtain a first steady-state response current of the gas of known concentration measured by the first measuring unit; The valve is opened, and the first measuring unit and the second measuring unit perform measurements together to obtain a second steady-state response current and a third steady-state response current of the gas of known concentration measured by the first measuring unit and the second measuring unit; The activity of the electrode to be tested is determined according to the known gas concentration and the first steady-state response current, the second steady-state response current, and the third steady-state response current.

9. The electrode activity measurement method according to claim 8, characterized in that: The activity of the electrode to be tested is determined according to the known gas concentration and the first steady-state response current, the second steady-state response current, and the third steady-state response current, using the following formula: R 15 =[((I 15b +I 230b )-I 15a ) / I 15a I 15b ]C1 Among them, R 15 is the activity of the electrode to be tested, C1 is the known gas concentration, I 15a is the first steady-state response current, I 15b is the second steady-state response current, I 33b is the third steady-state response current.

10. The electrode activity measurement method according to claim 8, characterized in that: The valve is opened, the first measuring unit and the second measuring unit perform measurements together, and a second steady-state response current and a third steady-state response current of the gas with a known concentration measured by the first measuring unit are obtained; comprising: Controlling the gas with known concentration to pass through the diffusion channel and then enter the first measuring unit; A portion of the gas with known concentration reacts with the electrode to be tested to obtain the second steady-state response current; Another portion of the gas with known concentration enters the second measuring unit through the valve and reacts with the working electrode to obtain the third steady-state response current.

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