Preparation, application and device of oxygen-vacancy-rich electrode for portable detection of chemical oxygen demand

Abstract

The present invention belongs to the field of electrochemical rapid detection, and provides a preparation, application and device of an oxygen-vacancy-rich electrode for portable detection of chemical oxygen demand. The present invention prepares an electrode rich in oxygen vacancies by a hydrothermal method. The electrode can generate sufficient hydroxyl radicals at an appropriate potential to completely oxidize organic matter in water, and the detection sensitivity of the electrode to chemical oxygen demand is significantly improved. The main body of the portable electrochemical detection device for chemical oxygen demand includes a three-electrode system, a built-in electrochemical module chip, a touch screen and a built-in battery; the built-in electrochemical module chip is coupled internally to the device to miniaturize the detection device, avoiding the inconvenience of conventional electrochemical portable detection requiring an external electrochemical workstation, and the portability is significantly improved. It has the advantages of sensitivity, rapidity, and anti-interference for direct portable detection of chemical oxygen demand, and is suitable for on-site detection.

Description

Technical Field

[0001] The invention belongs to the field of electrochemical rapid detection, and relates to the preparation of an electrode rich in oxygen vacancies and a portable device for electrochemically detecting chemical oxygen demand, which can be used to measure the chemical oxygen demand concentration in environmental water bodies. Background Art

[0002] Chemical oxygen demand (COD) refers to the amount of oxidants consumed by reducing substances in water under certain conditions, expressed in mg / L. It is an indicator of the amount of reducing substances in water. Reducing substances in water include various organic compounds, nitrites, ferrous salts, and others, primarily organic compounds. Therefore, COD is also measured as an indicator of the amount of organic matter in water. Rapid, real-time COD monitoring is of great environmental significance.

[0003] Currently, there are many methods for measuring COD. Among these, electrochemical methods, which generate hydroxyl radicals to measure COD, are a major breakthrough in COD measurement due to their simplicity, quick operation, and the absence of chemical reagents. These methods primarily include potentiostatic coulometry and potentiostatic amperometry. It is reported that the detection mechanism of most current COD electrochemical sensors is based on the electrochemical signal generated by hydroxyl radicals generated on the surface of the electrode material when they oxidize organic matter in water.

[0004] However, the electrode material used for chemical oxygen demand detection has a low yield of hydroxyl radicals, and the electrode needs to be connected to an external electrochemical workstation and a mobile device to measure the chemical oxygen demand, and the portability needs to be further improved. Based on the above-mentioned problems, the present invention introduces oxygen vacancies in the detection process. Oxygen vacancies with functional defects can increase the reaction active sites of the material and thus increase the yield of hydroxyl radicals. Since the electrochemical module is the core component of the electrochemical workstation, directly coupling and packaging the electrochemical module with the front-end working electrode system can achieve further miniaturization of the detection electrode equipment. Summary of the Invention

[0005] To address the problem of portable electrochemical detection of chemical oxygen demand (COD), the present invention provides a method for preparing an electrode rich in oxygen vacancies. This electrode significantly improves the detection sensitivity of COD. Based on this electrode, an integrated electrode device coupled with an electrochemical module is developed, which further miniaturizes the COD sensor, significantly improves its portability, and is more suitable for field applications.

[0006] The technical solution of the present invention:

[0007] A method for preparing an oxygen vacancy-rich electrode for portable detection of chemical oxygen demand, comprising the following steps:

[0008] 1) Tetrabutyl titanate and ascorbic acid were mixed evenly, and an ethanol-water mixed solution was slowly added and stirred evenly. After the reaction was completed, a precursor 1 was obtained;

[0009] in,

[0010] The volume ratio of ethanol to water in the ethanol-water mixed solution is 7:(1-5), the volume ratio of the tetrabutyl titanate and ascorbic acid mixed solution to the ethanol-water mixed solution is 1:(5-20), and the volume-mass ratio of tetrabutyl titanate to ascorbic acid is 10:(1-10), mL / g;

[0011] The reaction time is 0.5 to 1 hour;

[0012] 2) Precursor 1 is reacted under certain temperature conditions, then taken out and passed through a membrane, which is cleaned with ethanol and water respectively and then vacuum dried to obtain precursor 2;

[0013] in,

[0014] Certain temperature conditions: temperature is 80-200℃, heating rate is 5℃ / min, reaction time is 10-20h;

[0015] 3) Precursor 2 is calcined at high temperature under argon protection to obtain anatase-rutile homojunction titanium dioxide with oxygen vacancies;

[0016] in,

[0017] The high temperature calcination temperature is 600-1000°C, the heating rate is 5°C / min, and the high temperature calcination time is 1-5h;

[0018] 4) adding the anatase-rutile homojunction titanium dioxide with oxygen vacancies synthesized in step 3 to the aqueous solution containing Nafion 117, and sonicating for 1 hour to mix the two to obtain an anatase-rutile homojunction titanium dioxide solution with oxygen vacancies;

[0019] in,

[0020] The volume concentration of the aqueous solution containing Nafion 117 is 0.5 to 2.5 μL / mL, and the concentration of the anatase-rutile homojunction type titanium dioxide solution having oxygen vacancies is 0.5 to 2 mg / mL;

[0021] 5) applying an anatase-rutile homojunction titanium dioxide solution with oxygen vacancies to the surface of a glassy carbon electrode and allowing it to air dry to form an oxygen vacancy-rich electrode as a working electrode;

[0022] in,

[0023] The modification amount of anatase-rutile homojunction titanium dioxide solution with oxygen vacancies is 0.5-1.5 μL / mm 2 ;

[0024] The glassy carbon electrode is a threaded detachable electrode.

[0025] A method for detecting chemical oxygen demand using an oxygen vacancy-rich electrode as a detection electrode comprises the following steps:

[0026] A three-electrode system is constructed with an oxygen-rich vacancy electrode as a working electrode, a platinum sheet as a counter electrode, and a silver / silver chloride as a reference electrode. After a test solution is mixed with an electrolyte solution, the three-electrode system is completely immersed, and detection is performed using an electrochemical detector to measure the current value. Based on the measured current value, a standard curve of concentration and current is drawn using glucose as a chemical oxygen demand indicator to calculate the concentration of chemical oxygen demand in the test sample.

[0027] in,

[0028] The electrolyte solution is 0.2 mol / L sodium sulfate solution, which is mixed with the test solution in a 1:1 volume ratio;

[0029] The electrochemical detector measurement technique was the current-time curve method, and the applied potential was +1.0 to +2.2 V;

[0030] The standard curve is obtained by using glucose as a chemical oxygen demand indicator, recording the electrochemical response signals of the working electrode to different concentrations of glucose in a sodium sulfate solution at a fixed potential using an electrochemical workstation, and obtaining a standard curve and a linear equation based on the change in the response signal, with the logarithm of the concentration value converted to chemical oxygen demand equivalent of glucose as the abscissa and the current value as the ordinate.

[0031] in,

[0032] The concentration of sodium sulfate solution is 0.1 mol / L;

[0033] The concentration of glucose is 1.0~300.0mg / L.

[0034] A portable electrochemical detection device for chemical oxygen demand (COD) to which the above detection method can be applied completely oxidizes organic matter in water into water and carbon dioxide through sufficient hydroxyl radicals generated by a working electrode rich in oxygen vacancies. The generated oxidation current is converted into a COD value by an electrochemical module chip, and the COD value is displayed in the numerical display area of ​​a touch screen through a set circuit, thereby realizing portable and sensitive detection of COD, including:

[0035] An oxygen-rich vacancy electrode (1) is used as a working electrode and connected to a first pure copper wire (2-1); a silver / silver chloride electrode sheet (4) is used as a reference electrode and is encapsulated in the outer layer of the working electrode with a polytetrafluoroethylene material (3-1) and connected to a second pure copper wire (2-2); a platinum sheet (5) is used as a counter electrode and is encapsulated in the lower layer of the reference electrode with a polytetrafluoroethylene material (3-2) and connected to a third pure copper wire (2-3); the three pure copper wires are connected to an electrochemical module chip (7) through a wire transfer interface (6), the electrochemical module chip (7) is connected to a built-in battery (9) through a fourth pure copper wire (2-4), and the touch display screen (10) is connected to the built-in battery (9) through a fifth pure copper wire (2-5); and the entire device is encapsulated with a stainless steel material (8), exposing the oxygen-rich vacancy electrode (1), the silver / silver chloride electrode sheet (4), the platinum sheet (5) and the touch display screen (10).

[0036] The operation mode is as follows: inserting the electrode device into the sample solution to be tested, clicking the test button (10-2) on the touch screen (10) to perform electrochemical testing through the electrochemical module chip, recording the current value in the built-in storage area (7-1) of the electrochemical module chip, reading the standard curve in the built-in storage area (7-1) and calculating the concentration of the sample to be tested, and feeding back the sample concentration to the numerical display area (10-1) of the touch screen;

[0037] Among them, the reference electrode encapsulation distance is 10 to 20 mm from the surface of the working electrode;

[0038] Wherein, the electrochemical module chip (7) is a PlamSensEmStat Pico dual-channel constant potential instrument module or a HY-MODU-05005 electrochemical module;

[0039] Wherein, the touch display screen (10) is a programmable integrated serial port display screen connected to the electrochemical module;

[0040] A standard curve drawn with glucose as a chemical oxygen demand indicator is stored in a built-in storage area (7-1) of the electrochemical module chip (7), and measurement data obtained from the test is also stored in the built-in storage area (7-1).

[0041] An electrochemical technology selection module is provided on the control panel of the touch display screen (10), for users to input different technical parameters to test the chemical oxygen demand of different water bodies.

[0042] The electrochemical module chip (7) can generate different electrochemical modes according to input instructions, including chronoamperometric curves and cyclic voltammetric curves.

[0043] Beneficial effects of the present invention: The chemical oxygen demand detection electrode rich in oxygen vacancies of the present invention can generate sufficient hydroxyl radicals at an appropriate potential and can detect chemical oxygen demand in water with high sensitivity. The established chemical oxygen demand detection method has a detection range of 1.0 to 300.0 mg / L for chemical oxygen demand, a detection limit of 0.1 mg / L, and a measurement time as short as about 30 seconds, which is much shorter than that of existing conventional chemical oxygen demand detectors. It does not require a complex sample pretreatment process, and the detection device is miniaturized by the built-in coupled electrochemical module chip, avoiding the inconvenience of conventional electrochemical portable detection requiring an external electrochemical workstation, thereby greatly improving the portability of the detection. The present invention has the advantages of low cost, easy operation, low detection limit, good stability, selectivity, anti-interference and portability. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Scanning electron microscope image of the synthesized titanium dioxide material rich in oxygen vacancies.

[0045] Figure 2 This is a structural diagram of a portable electrochemical detection device for chemical oxygen demand.

[0046] Figure 3 The figure shows the standard curve of chemical oxygen demand detected by the portable electrochemical detection device of chemical oxygen demand based on the chemical oxygen demand electrode rich in oxygen vacancies.

[0047] Figure 4 Scanning electron micrograph of the synthesized titanium dioxide material without oxygen vacancies.

[0048] Figure 5 The current-time curve of a portable electrochemical chemical oxygen demand detection device based on chemical oxygen demand electrodes rich in oxygen vacancies and without oxygen vacancies in glucose solution.

[0049] Figure 6 This is a test diagram of the anti-interference ability of a portable chemical oxygen demand electrochemical detection device based on a chemical oxygen demand electrode rich in oxygen vacancies.

[0050] In the figure: 1 oxygen-rich vacancy electrode; 2-1 first pure copper wire; 2-2 second pure copper wire; 2-3 third pure copper wire; 2-4 fourth pure copper wire; 2-5 fifth pure copper wire; 4 silver / silver chloride electrode sheet; 3-1 first layer of polytetrafluoroethylene material; 3-2 second layer of polytetrafluoroethylene material; 5 platinum sheet; 6 wire adapter; 7 electrochemical module chip; 7-1 built-in storage area; 8 stainless steel material; 9 built-in battery; 10 touch screen; 10-1 numerical display area; 10-2 test button. DETAILED DESCRIPTION

[0051] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0052] Example 1: Preparation of a Chemical Oxygen Demand Detection Electrode Rich in Oxygen Vacancies

[0053] 1) 2 mL of tetrabutyl titanate and 0.15 g of ascorbic acid were mixed uniformly, and 20 mL of a 7:3 ethanol-water mixed solution was slowly added, and the mixture was stirred at 350 rpm for 0.5 h to obtain Precursor 1;

[0054] 2) Transfer the precursor 1 to a high-pressure reactor and react in an oven at 90°C (heating rate of 5°C / min) for 12 hours. Then, remove the membrane, wash it with ethanol and water, and vacuum dry it to obtain the precursor 2.

[0055] 3) Precursor 2 was calcined at 800°C for 2 h under argon protection (heating rate of 5°C / min) to obtain anatase-rutile homojunction titanium dioxide with oxygen vacancies;

[0056] 4) 1 mg of the anatase-rutile homojunction titanium dioxide with oxygen vacancies synthesized in step 3 was added to 1 mL of an aqueous solution containing 2.5 μL of Nafion 117, and the mixture was ultrasonicated for 1 h to mix the two to obtain an anatase-rutile homojunction titanium dioxide solution with oxygen vacancies.

[0057] 5) 8 μL of anatase-rutile homojunction titanium dioxide solution with oxygen vacancies was drop-coated on the surface of a glassy carbon electrode and allowed to air-dry to prepare an electrode rich in oxygen vacancies as a working electrode;

[0058] The present invention uses tetrabutyl titanate, ethanol, and water as raw materials and ascorbic acid as a reducing agent to synthesize titanium dioxide rich in oxygen vacancies through a hydrothermal method. The scanning electron microscope image of the titanium dioxide material rich in oxygen vacancies prepared by the method of the present invention is shown in FIG. Figure 1 , Figure 1 The titanium dioxide is shown to be a spherical crystal with block-like stacking growth.

[0059] Example 2: Portable electrochemical detection device for chemical oxygen demand

[0060] The structure diagram of the portable chemical oxygen demand electrochemical detection device is as follows Figure 2 As shown, the construction is as follows:

[0061] The surface of the working electrode obtained in Example 1 is modified with a titanium dioxide material rich in oxygen vacancies; the working electrode is a threaded detachable electrode that can be disassembled for cleaning or replacement; the working electrode, the counter electrode and the reference electrode are connected by pure copper wires, which can be inserted into a built-in electrochemical module chip through a three-wire wire adapter to detect the readings; the built-in electrochemical module chip is used to provide a +2.0V constant potential. When the test button on the touch display is pressed, the oxidation current value at this potential is recorded and stored in the built-in storage area, and is calculated through the standard curve in the built-in storage area and displayed in the numerical display area of ​​the touch display as the concentration of chemical oxygen demand.

[0062] The sample testing steps are as follows:

[0063] First, the sample to be tested is evenly mixed with the electrolyte solution. Then, the three electrodes of the portable chemical oxygen demand electrochemical detection device are completely immersed in the mixed solution to be tested. The built-in electrochemical module chip tests the time-current curve at a constant voltage of +2.0V, records the current value at the 30th second, and calculates based on the standard curve built into the storage area. The measured chemical oxygen demand concentration is stored in the built-in storage area of ​​the electrochemical module chip and displayed in the numerical display area of ​​the touch screen.

[0064] Example 3: Standard Curve

[0065] In the portable electrochemical detection device for chemical oxygen demand of the present invention, a standard curve between chemical oxygen demand concentration and current value is built into the built-in storage area of ​​the electrochemical module chip. The method for drawing the standard curve is as follows: using glucose as the chemical oxygen demand indicator substance, different known concentrations of glucose (concentration range: 1.0-300.0 mg / L) are prepared in a 0.1 mol / L sodium sulfate solution, and a chemical oxygen demand detection electrode rich in oxygen vacancies is inserted into each concentration of glucose solution. The built-in electrochemical module chip tests the time-current curve at a constant voltage of +2.0V, records the current-time curve for 30 seconds and stores it in the built-in storage area, and draws a standard curve with the chemical oxygen demand concentration as the horizontal axis and the current value at the 30th second as the vertical axis. Figure 3 As shown, the linear equation is I / μA=8.25×Log[c / mg / L]+7.43(R 2 =0.991), the detection limit was 0.10 mg / L;

[0066] Comparative Example 1: Preparation of a Chemical Oxygen Demand Detection Electrode without Oxygen Vacancies

[0067] Referring to Example 1, without adding ascorbic acid and keeping other conditions unchanged, a chemical oxygen demand detection electrode without oxygen vacancies was obtained; the scanning electron microscope image of the synthesized titanium dioxide material without oxygen vacancies is as follows: Figure 4 As shown;

[0068] The working electrode in the portable electrochemical detection device for chemical oxygen demand of Example 2 was screwed off and replaced with a chemical oxygen demand detection electrode without oxygen vacancies. Sample testing was performed according to Example 2. The built-in electrochemical module chip tested the time-current curve at a constant voltage of +2.0V, and the current value of 200.0 mg / L glucose at 30 seconds was recorded. The test results were compared with those of the portable electrochemical detection device with the chemical oxygen demand detection electrode rich in oxygen vacancies as the working electrode. Figure 5 As shown in the figure, it can be seen that the response current value of the electrode without oxygen vacancies used for comparison to chemical oxygen demand is extremely low, but the response current value of the electrode rich in oxygen vacancies synthesized in Example 1 to chemical oxygen demand is significantly enhanced. This performance improvement is attributed to the introduction of oxygen vacancy defect structures, which serve as reaction active sites and accelerate electron transfer, thereby effectively increasing the hydroxyl radical yield of the electrode and thus improving the detection signal of chemical oxygen demand.

[0069] Test Example 1: Anti-interference ability test of a portable electrochemical chemical oxygen demand detection device based on the chemical oxygen demand detection electrode rich in oxygen vacancies

[0070] Take 25mL of 0.1mol / L sodium sulfate solution in a beaker and completely immerse the three-electrode area of ​​the portable chemical oxygen demand electrochemical detection device. The built-in electrochemical module chip tests the time-current curve at a constant voltage of +2.0V and records the current value. During this period, glucose with a final concentration of 20mg / L (as a chemical oxygen demand indicator), sodium nitrate with a final concentration of 0.1mol / L, potassium sulfate, calcium sulfate, and magnesium sulfate are added to the beaker in sequence every 60 seconds to test the anti-interference ability of the device. The results are as follows Figure 6 As shown, the electrochemical response of the portable chemical oxygen demand electrochemical detection device to chemical oxygen demand has basically not changed, indicating that it has strong anti-interference ability.

[0071] Experimental Example 2: Application of a portable electrochemical chemical oxygen demand detection device based on the chemical oxygen demand detection electrode rich in oxygen vacancies, i.e., detecting the chemical oxygen demand content in environmental water

[0072] 1) Mix the environmental water sample with 0.2 mol / L sodium sulfate solution in a 1:1 volume ratio.

[0073] 2) Place 25 mL of the mixed solution in a beaker and completely immerse the three-electrode area of ​​a portable electrochemical COD detector. The built-in electrochemical module chip measures the time-current curve at a constant voltage of +2.0 V, and the current value is recorded. Each water sample is tested three times independently and compared with the results of the standard potassium dichromate method. The experimental results for the actual water samples are shown in Table 1.

[0074] Table 1

[0075]

[0076]

[0077] The preferred embodiments of this patent are described in detail above. However, this patent is not limited to the above embodiments. Other variations or modifications can be made within the knowledge of ordinary technicians in this field. It is not necessary and impossible to list all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included in the scope of protection of the claims of this invention.

Claims

1. A method for preparing an oxygen-vacancy-rich electrode for portable detection of chemical oxygen demand, characterized in that: Here are the steps: 1) Tetrabutyl titanate and ascorbic acid were mixed evenly, and an ethanol-water mixed solution was slowly added and stirred evenly. After the reaction was completed, a precursor 1 was obtained; 2) Precursor 1 is reacted under certain temperature conditions, then taken out and passed through a membrane, which is cleaned with ethanol and water respectively and then vacuum dried to obtain precursor 2; 3) Precursor 2 is calcined at high temperature under argon protection to obtain anatase-rutile homojunction titanium dioxide with oxygen vacancies; 4) adding the anatase-rutile homojunction titanium dioxide with oxygen vacancies synthesized in step 3 to the aqueous solution containing Nafion 117, and sonicating for 1 hour to mix the two to obtain an anatase-rutile homojunction titanium dioxide solution with oxygen vacancies; 5) An anatase-rutile homojunction titanium dioxide solution with oxygen vacancies is drop-coated on the surface of a glassy carbon electrode and allowed to air-dry to prepare an oxygen vacancy-rich electrode as a working electrode.

2. The preparation method according to claim 1, characterized in that In step 1), The volume ratio of ethanol to water in the ethanol-water mixed solution is 7:(1-5), the volume ratio of the tetrabutyl titanate and ascorbic acid mixed solution to the ethanol-water mixed solution is 1:(5-20), and the volume-mass ratio of tetrabutyl titanate to ascorbic acid is 10:(1-10), ml / g; The reaction time is 0.5 to 1 hour.

3. The preparation method according to claim 1, characterized in that In step 2), Certain temperature conditions: temperature is 80-200℃, heating rate is 5℃ / min, and reaction time is 10-20h.

4. The preparation method according to claim 1, characterized in that In step 3), The high-temperature calcination temperature is 600-1000° C., the heating rate is 5° C. / min, and the high-temperature calcination time is 1-5 hours.

5. The preparation method according to claim 1, characterized in that In step 4), The volume concentration of the aqueous solution containing Nafion 117 is 0.5 to 2.5 μL / mL, and the concentration of the anatase-rutile homojunction type titanium dioxide solution having oxygen vacancies is 0.5 to 2 mg / mL.

6. The preparation method according to claim 1, characterized in that In step 4), The modification amount of anatase-rutile homojunction titanium dioxide solution with oxygen vacancies is 0.5-1.5 μL / mm 2 ; The glassy carbon electrode is a threaded detachable electrode.

7. A method for detecting chemical oxygen demand using the oxygen vacancy electrode obtained by the preparation method according to any one of claims 1 to 6 as a detection electrode, characterized in that: The steps include: A three-electrode system is constructed with an oxygen-rich vacancy electrode as a working electrode, a platinum sheet as a counter electrode, and a silver / silver chloride as a reference electrode. After a test solution is mixed with an electrolyte solution, the three-electrode system is completely immersed, and detection is performed using an electrochemical detector to measure the current value. Based on the measured current value, a standard curve of concentration and current is drawn using glucose as a chemical oxygen demand indicator to calculate the concentration of chemical oxygen demand in the test sample.

8. The detection method according to claim 7, characterized in that The electrolyte solution is 0.2 mol / L sodium sulfate solution, which is mixed with the test solution in a 1:1 volume ratio; The method used for electrochemical detection was the current-time curve method, and the applied potential was +1.0 to +2.2 V; The standard curve is obtained by using glucose as the indicator substance for chemical oxygen demand, and using an electrochemical workstation to record the electrochemical response signals of the working electrode to different concentrations of glucose in a sodium sulfate solution at a fixed potential. Based on the change in the response signal, the logarithm of the concentration value converted to chemical oxygen demand equivalent of glucose is taken as the abscissa, and the current value is taken as the ordinate to obtain the standard curve and linear equation; in, The concentration of sodium sulfate solution is 0.1 mol / L; The concentration of glucose is 1.0~300.0mg / L.

9. A portable electrochemical detection device for chemical oxygen demand, characterized in that: The portable electrochemical detection device for chemical oxygen demand comprises: The oxygen-rich vacancy electrode (1) is used as a working electrode and connected to a first pure copper wire (2-1); the silver / silver chloride electrode sheet (4) is used as a reference electrode and is encapsulated in the outer layer of the working electrode with a polytetrafluoroethylene material (3-1) and connected to a second pure copper wire (2-2); the platinum sheet (5) is used as a counter electrode and is encapsulated in the lower layer of the reference electrode with a polytetrafluoroethylene material (3-2) and connected to a third pure copper wire (2-3); the three pure copper wires are connected to an electrochemical module chip (7) through a wire adapter (6), the electrochemical module chip (7) is connected to a built-in battery (9) through a fourth pure copper wire (2-4), and the touch screen (10) is connected to the built-in battery (9) through a fifth pure copper wire (2-5); the entire device is encapsulated with a stainless steel material (8), exposing the oxygen-rich vacancy electrode (1), the silver / silver chloride electrode sheet (4), the platinum sheet (5) and the touch screen (10); The operation mode is as follows: inserting the electrode device into the sample solution to be tested, clicking the test button (10-2) on the touch screen (10) to perform electrochemical testing through the electrochemical module chip, recording the current value in the built-in storage area (7-1) of the electrochemical module chip, reading the standard curve in the built-in storage area (7-1) and calculating the concentration of the sample to be tested, and feeding back the sample concentration to the numerical display area (10-1) of the touch screen.

10. The portable electrochemical detection device for chemical oxygen demand according to claim 9, characterized in that: The reference electrode encapsulation distance is 10 to 20 mm from the working electrode surface; The electrochemical module chip (7) is a dual-channel potentiostat module or an electrochemical module; The touch screen (10) is a programmable integrated serial port display screen connected to the electrochemical module; A standard curve drawn using glucose as a chemical oxygen demand indicator is stored in a built-in storage area (7-1) of the electrochemical module chip (7), and measurement data obtained from the test is also stored in the built-in storage area (7-1); An electrochemical technology selection module is provided on the control panel of the touch display screen (10), for users to input different technical parameters to test the chemical oxygen demand of different water bodies; The electrochemical module chip (7) generates different electrochemical modes according to input instructions, including chronoamperometric curves and cyclic voltammetric curves.

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