A chip-type hemispherical copper oxide microelectrode, its preparation method and application

Abstract

The present invention provides a chip-type hemispherical copper oxide microelectrode, a preparation method and an application thereof. The copper oxide microelectrode comprises nano-copper and nano-copper oxide that are in-situ grown and stacked on a conductive substrate to form a semi-microsphere, wherein the surface layer of the semi-microsphere is formed by stacking the nano-copper oxide. The chip-type hemispherical copper oxide microelectrode, the preparation method and the application thereof provided by the present invention have a rough interface structure and exposed stereoscopic crystal planes at the same time. Therefore, the constructed microelectrode has good stability and reproducibility. When it is applied to a sensor for detecting glucose, excellent sensitivity, anti-interference property and stability can be obtained. At the same time, the semi-microspheres of the microelectrode are not easy to fall off, and the performance difference between the microelectrodes is small, making it possible to mass-produce enzyme-free glucose sensors in large quantities.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and particularly to a chip-shaped hemispherical copper oxide microelectrode, a preparation method and an application thereof. Background Art

[0002] Glucose sensors have experienced the development of enzyme and enzyme-free sensors. However, enzyme sensors cannot get rid of the inherent instability drawbacks of enzymes. In addition, the application of enzymes is also restricted by other conditions, such as pH, temperature, humidity and oxygen dependence. Coupled with the high price of enzymes, the sensor always faces the problem of construction cost. Based on the above factors, the research on enzyme-free glucose sensors has received great attention. At present, enzyme-free glucose sensors have been widely used in the fields of biomedicine, food industry, ecological methods, etc., and a series of metals and metal oxides, bimetallic nanomaterials, alloys, metal / metal oxide-carbon nanotube composites that can be applied to enzyme-free glucose sensors have also been proposed. However, the results show that the applied enzyme-free glucose sensors generally have technical defects of poor stability and low sensitivity.

[0003] Here, an electrode with high electrocatalytic activity plays a crucial role in improving the stability and sensitivity of enzyme-free glucose sensors. It can accelerate the electron transfer rate and reduce the reaction activation energy. For many years, researchers have been committed to developing electrodes with high electrocatalytic activity, such as increasing the specific surface area of the active material used for the electrode, increasing the electrochemically active sites, or regulating the mass transfer and diffusion of reactants at the electrode-electrolyte interface. Among them, non-precious metal transition metal active materials with a three-dimensional spherical-like structure and a rough interface have attracted extensive attention in electrocatalytic chemistry due to their unique properties. Such metal materials have a good catalytic structure, and their rough interface structure can effectively promote the mass transfer and diffusion of reactants; the three-dimensional structure can expose multiple crystal planes, thereby providing diverse electrochemically active sites. The unique properties of nanosphere-structured metal materials provide potential application value for electrocatalysis and electroanalysis.

[0004] In terms of electrode construction, the known methods for constructing an electrochemical working electrode are the drop-casting method, the electrochemical deposition method, and the template synthesis method. Among them, the electrochemical deposition method is widely used. It is driven by an electrochemical reaction and therefore occurs selectively on a conductive and electrochemically active surface. It can be well controlled by potential / current and time and has an advantage in forming complex geometric shape changes, thereby forming certain specific structures. This method has harsh conditions and requires specific electrochemical parameters (voltage, time, etc.), electrolyte types and concentrations, etc. Moreover, it lacks a certain controllability in the construction of an ordered spherical structure. Therefore, developing a controllable and inexpensive method for constructing an electrode with a nanosphere structure is still a great challenge and of great significance. Summary of the Invention

[0005] Based on the technical problems existing in the background art, the present invention proposes a chip - type hemispherical copper oxide micro - electrode, a preparation method thereof and an application. The copper oxide micro - electrode has both a rough interface structure and exposed three - dimensional crystal planes. Therefore, the constructed micro - electrode has good stability and reproducibility. When it is applied to a sensor for glucose detection, excellent sensitivity, anti - interference ability and stability can be obtained. At the same time, the semi - microspheres of the micro - electrode are not easy to fall off, and the performance difference between micro - electrodes is small, making the large - scale batch production of enzyme - free glucose sensors possible.

[0006] A chip - type hemispherical copper oxide micro - electrode proposed by the present invention includes nano - copper and nano - copper oxide that are in - situ grown and stacked on a conductive substrate to form semi - microspheres. Among them, the surface layer of the semi - microspheres is formed by stacking the nano - copper oxide.

[0007] In the present invention, by using nano - copper and nano - copper oxide that are in - situ grown and stacked on a conductive substrate to form semi - microspheres, the micro - electrode has a three - dimensional spherical structure and a rough interface structure. The synergistic effect of these two structures greatly improves the sensitivity of glucose detection, and has an extremely wide linear range and an extremely low detection limit. At the same time, when the surface layer of the semi - microspheres is formed by stacking the nano - copper oxide, a dense copper oxide thin film is formed on the surface of the micro - electrode. Since copper oxide has good electro - catalytic performance, the copper oxide micro - electrode further has the structural advantage of exposing high - activity sites, thereby obtaining stronger electro - catalytic activity performance.

[0008] Preferably, the size of the semi - microspheres is 2 - 20 μm, and the thickness of the surface layer of the semi - microspheres is 50 - 500 nm;

[0009] Preferably, the size of the semi - microspheres is 5 μm.

[0010] In the present invention, when the size of the semi - microspheres is 5 μm, the corresponding copper oxide micro - electrode has the best electro - catalytic activity performance.

[0011] The present invention also proposes a preparation method of the above - mentioned chip - type hemispherical copper oxide micro - electrode, including: using an electrochemical deposition method to in - situ grow and stack nano - copper on a conductive substrate to form semi - microspheres, and then further subjecting the nano - copper on the surface layer of the semi - microspheres to in - situ oxidation heat treatment to form copper oxide, thus obtaining the copper oxide micro - electrode.

[0012] In the present invention, transition metal copper is in-situ deposited on a conductive substrate by an electrochemical deposition method, and by controlling its deposition process, the transition metal copper is stacked to form semi-microspheres, and then through oxidation heat treatment, copper oxide is in-situ generated on the surface layer of the semi-microspheres from the transition metal copper, thereby forming a copper oxide microelectrode with a surface layer composed of copper oxide and a morphology also being semi-microspheres; for those skilled in the art, the copper oxide microelectrode with such a microscopic morphology has both a rough interface structure and an exposed three-dimensional crystal plane energy, so it can be directly used for the rapid electrochemical determination of glucose and has excellent sensitivity, anti-interference ability and stability.

[0013] Preferably, the electrochemical deposition method specifically includes: using a bare microchip electrode as the working electrode, a divalent copper salt solution as the electrolyte solution, and performing potentiostatic deposition under the cooperation of a counter electrode and a reference electrode, that is, in-situ growing and stacking nano-copper in the form of semi-microspheres on the working electrode;

[0014] Among them, the bare microchip electrode includes a gold conductive substrate and a silicon dioxide thin film located on the gold conductive substrate and having an open microporous structure;

[0015] Preferably, the diameter of the open micropores is 2 - 10 μm.

[0016] In the present invention, by selecting a bare microchip electrode including a gold conductive substrate and a silicon dioxide thin film located on the gold conductive substrate and having an open microporous structure, when the gold conductive substrate in the open microporous structure area of the silicon dioxide thin film in the bare microchip electrode is used as the working area, the contact area between the conductive substrate and the electrodeposition solution can be controlled, thereby controlling the spatial stacking morphology of the deposited transition metal copper, and finally forming hemispherical nano-copper, and then through oxidation heat treatment, a copper oxide microelectrode with the same morphology can also be obtained.

[0017] Preferably, the electrolyte solution further includes a perchlorate solution;

[0018] Preferably, the electrolyte solution includes a CuSO 4 solution with a concentration of 0.5 - 1.5 mmol / L and a NaClO 4 solution with a concentration of 5 - 15 mmol / L.

[0019] In the present invention, perchlorate as an additive can inhibit the hydrolysis of copper ions and contribute to the reduction of Cu 2+ to Cu and deposition on the surface of the conductive substrate.

[0020] Preferably, the voltage of the potentiostatic deposition is kept constant at -(0.3 - 0.5) V, and the deposition time is 5 - 75 s.

[0021] In the present invention, "constant potential deposition", as a technique for in-situ growth of nanoparticles, can control the orderliness, thickness, and uniformity of the grown particles at the nano- and micro-levels. By controlling the electrochemical parameters (such as voltage, time, etc.) during "constant potential deposition", the present invention can further control the size on the basis of the formed hemispherical copper oxide, and finally obtain a copper oxide half-microsphere with controllable size.

[0022] Preferably, in actual operation, in the electrochemical deposition method, the gold conductive substrate located in the open microporous structure region of the silica thin film in the bare microchip electrode is used as the working area, a silver wire electrode is used as the counter electrode. After connecting the silver wire electrode and the reference electrode together, the silver wire electrode is inserted into a capillary tube, and an electrolyte solution is injected into the capillary tube. Then, the end of the capillary tube is brought close to the surface of the working area of the bare microchip electrode for constant potential deposition.

[0023] In the present invention, when electrochemical deposition is achieved through the above operation method, the use of conductive glue can be avoided, thereby avoiding the situation that the conductive glue is carbonized and deposited on the surface of the microelectrode during subsequent thermal oxidation treatment, and thus reducing the sensitive response of the copper oxide microelectrode to glucose detection.

[0024] Preferably, the temperature of the thermal oxidation treatment is 200 - 300 °C, and the time is 3 - 8 min.

[0025] In the present invention, through thermal oxidation treatment, hemispherical nano-copper is oxidized to form hemispherical nano-copper oxide. During this in-situ oxidation process, the nano-copper particles are sintered with each other and tightly bonded to the conductive substrate, and are not easily detached, thereby enhancing the performance stability between the hemispherical nano-copper oxide and the conductive substrate, enabling the obtained copper oxide microelectrode to work stably for a long time when detecting glucose, improving the reliability of the enzyme-free glucose sensor, and making it possible for the enzyme-free glucose sensor to be widely applied in blood glucose or food industry detection. In addition, the in-situ oxidation method also provides an idea for constructing other micro-nano devices.

[0026] The present invention also proposes an enzyme-free glucose sensor, which uses the above-mentioned copper oxide microelectrode or the copper oxide microelectrode prepared by the above preparation method as the working electrode.

[0027] Preferably, the detection sensitivity of glucose can reach 340 μA·μM -1 ·cm -2 .

[0028] The present invention innovatively applies the potentiostatic deposition technique to the preparation of hemispherical copper oxide microelectrodes, resulting in copper oxide microelectrodes with a uniform, dense, and ordered structure and a rough interface. Moreover, hemispherical copper oxide microelectrodes of different sizes are obtained. On the one hand, these copper oxide microelectrodes improve electron conduction, and on the other hand, they also greatly reduce the performance differences between the preparations of different microelectrodes, making it possible to mass-produce microchip electrodes in large quantities.

[0029] The copper oxide microelectrodes of the present invention can be applied to enzyme-free glucose sensors, which can be directly used for the rapid electrochemical determination of glucose, and have high detection efficiency for glucose, good reproducibility, and can be reused. Brief Description of the Drawings

[0030] Figure 1 It is a schematic structural diagram of the bare microchip electrode described in the present invention: including the front view of the bare microchip electrode, a partial enlarged view of the working area of the bare microchip electrode, and a cross-sectional view of the bare microchip electrode;

[0031] Figure 2 It is a flowchart for the preparation of the copper oxide microelectrodes described in the present invention;

[0032] Figure 3 It is an SEM image of the copper oxide microelectrodes described in the present invention: (a) is the SEM image of the copper oxide microelectrodes in Example 2; (b) is the SEM image of the copper oxide microelectrodes in Example 1; (c) is the SEM image of the copper oxide microelectrodes in Example 3; (d) is the SEM image of the copper oxide microelectrodes in Example 4;

[0033] Figure 4 It is an SEM image of the cutting interface of the copper oxide microelectrodes in Example 1 of the present invention and an element mapping image on the cutting interface;

[0034] Figure 5 It is a CV response curve graph of the bare microchip electrode, copper microelectrode, and copper oxide microelectrode in Example 1 of the present invention for glucose: (a) is a comparative CV response curve graph of the bare microchip electrode, copper microelectrode, and copper oxide microelectrode in Example 1 for 0.1 mM glucose; (b) is a current response curve graph of the bare microchip electrode in Example 1 for the blank bottom solution and 0.1 mM glucose; (c) is a current response curve graph of the copper microelectrode in Example 1 for the blank bottom solution and 0.1 mM glucose; (d) is a current response curve graph of the copper oxide microelectrode in Example 1 for the blank bottom solution and 0.1 mM glucose;

[0035] Figure 6Test diagrams of anti-interference property, stability and repeatability of the copper oxide microelectrode in Example 1 of the present invention for glucose detection: (a) Real-time response curve diagram of the copper oxide microelectrode in Example 1 for non-carbohydrate interferents during glucose detection; (b) Real-time response curve diagram of the copper oxide microelectrode in Example 1 for carbohydrate interferents during glucose detection; (c) Response value result diagram of the copper oxide microelectrode in Example 1 for the same concentration of glucose at the same interval of days.

[0036] Figure 7 Chronoamperometry curve diagrams of the copper oxide microelectrode in Example 1 of the present invention for different concentrations of glucose: (a) Chronoamperometry curve diagrams of the copper oxide microelectrode in Example 1 for different concentrations of glucose within 0 - 1800 s, where the inset is the enlarged current curve diagram of the copper oxide microelectrode in Example 1 for different concentrations of glucose within 0 - 800 s; (b) Current calibration curve diagram of the copper oxide microelectrode in Example 1 at the corresponding glucose concentrations. Detailed implementation manners

[0037] Next, the technical solutions of the present invention will be described in detail through specific examples, but it should be clearly stated that these examples are for illustrative purposes only and are not construed as limiting the scope of the present invention.

[0038] Example 1

[0039] This example provides a chip-type hemispherical copper oxide microelectrode, which is prepared by the following method:

[0040] Referring to Figure 1 、 2 As shown, a bare microchip electrode (including a gold conductive substrate 1 and a silica thin film 2 with an open microporous structure located on the gold conductive substrate) is used as the working electrode and connected to a wire (such as a Culead wire), exposing the gold conductive substrate in the area (lead) of the open micropores (with an open micropore diameter of 5 μm) of the silica thin film 2, and using it as the working area of the bare microchip electrode; using a silver wire electrode (with a diameter of 0.25 mm) as the counter electrode and Ag / AgCl as the reference electrode, connecting the reference electrode and the counter electrode together with the silver wire electrode, then threading the silver wire electrode into a capillary tube, and then using a micro syringe to take a small amount of electrolyte solution (containing 1 mmol / L of CuSO 4 solution and 10 mmol / L of NaClO 4Inject the (solution) into the capillary, and then bring the end of the capillary close to the surface of the working area of the bare microchip electrode for potentiostatic deposition. Set the potential of the potentiostatic deposition to be constant at -0.42 V and the deposition time to be 15 s. After the deposition is completed, a hemispherical copper microelectrode is obtained. Then, place the hemispherical copper microelectrode in a muffle furnace and calcine it at 250 °C for 5 min to obtain a chip-type hemispherical copper oxide microelectrode with a size of 5 μm.

[0041] Perform scanning electron microscope characterization on the hemispherical copper oxide microelectrode prepared in the above example, and the results are as Figure 3 (b) shown, Figure 3 (b) is the SEM image of the copper oxide microelectrode described in Example 1. Refer to Figure 3 (b). It can be seen that the copper oxide microelectrode is a semi-microsphere structure, and its structure is uniform, dense, ordered and has a rough interface.

[0042] Use the FIB (Focused Ion Beam) technology to perform cross-section cutting and analysis on the hemispherical copper oxide microelectrode prepared in the above example, and the results are as Figure 4 shown, Figure 4 is the SEM image of the corresponding cutting interface and the element mapping image on the corresponding cutting interface of the copper oxide microelectrode described in Example 1 after being cut by the FIB technology. Refer to Figure 4 It can be seen that the cross-section of the hemispherical copper oxide microelectrode has a rough copper oxide surface layer with a thickness of about 200 nm, and the internal structure is relatively flat and smooth, and is copper that has not been thermally oxidized and cuprous oxide that has not been completely thermally oxidized.

[0043] Example 2

[0044] This example presents a chip-type hemispherical copper oxide microelectrode, which is prepared by the method described in Example 1. Except that the diameter of the open micropores in the bare microchip electrode is set to 2 μm, and when performing potentiostatic deposition, the potential of the potentiostatic deposition is set to be constant at -0.42 V and the deposition time is 5 s, and finally a chip-type hemispherical copper oxide microelectrode with a size of 2 μm is obtained.

[0045] Perform scanning electron microscope characterization on the hemispherical copper oxide microelectrode prepared in the above example, and the results are as Figure 3 (a) shown, Figure 3 (a) is the SEM image of the copper oxide microelectrode described in Example 2. Refer to Figure 3 (a). It can be seen that the copper oxide microelectrode is also a semi-microsphere structure, and its structure is also uniform, dense, ordered and has a rough interface.

[0046] Example 3

[0047] This embodiment provides a chip-type hemispherical copper oxide microelectrode, which is prepared by the method described in Example 1. Except that the diameter of the open micropores in the bare microchip electrode is set to 9 μm, and during potentiostatic deposition, the potential of potentiostatic deposition is set to be constant at -0.42 V, and the deposition time is 45 s, finally obtaining a chip-type hemispherical copper oxide microelectrode with a size of 10 μm.

[0048] The hemispherical copper oxide microelectrode prepared in the above embodiment was characterized by scanning electron microscopy, and the results are as Figure 3 (c) shown, Figure 3 (c) is the SEM image of the copper oxide microelectrode described in Example 3. Referring to Figure 3 (c), it can be seen that the copper oxide microelectrode is also a semi-microsphere structure, and its structure is also uniform, dense, ordered and has a rough interface.

[0049] Example 4

[0050] This embodiment provides a chip-type hemispherical copper oxide microelectrode, which is prepared by the method described in Example 1. Except that the diameter of the open micropores in the bare microchip electrode is set to 9 μm, and during potentiostatic deposition, the potential of potentiostatic deposition is set to be constant at -0.42 V, and the deposition time is 75 s, finally obtaining a chip-type hemispherical copper oxide microelectrode with a size of 20 μm.

[0051] The hemispherical copper oxide microelectrode prepared in the above embodiment was characterized by scanning electron microscopy, and the results are as Figure 3 (d) shown, Figure 3 (d) is the SEM image of the copper oxide microelectrode described in Example 3. Referring to Figure 3 (d), it can be seen that the copper oxide microelectrode is also a semi-microsphere structure, and its structure is also uniform, dense, ordered and has a rough interface.

[0052] Test Example 1:

[0053] The wire and the bare microchip electrode, hemispherical copper microelectrode, and hemispherical copper oxide microelectrode described in Example 1 were connected with conductive silver paste and insulating glue respectively. After natural drying, the packaged electrodes were obtained respectively; the packaged electrodes were placed in a three-electrode system as the working electrode, where the Pt wire electrode was the counter electrode and Ag / AgCl (1.0 M KCl) was the reference electrode. 10 mL of 0.1 mol / L phosphate buffer solution (PBS) aqueous solution was placed in the electrolytic cell, and a blank potential scan from -0.2 to 0.8 V was carried out by cyclic voltammetry (CV) using an electrochemical workstation. Then 0.1 mM glucose was added to the electrolytic cell, stirred evenly, and CV was repeated once. The results are as Figure 5 shown, Figure 5CV response curve graphs of the bare microchip electrode, copper microelectrode, and copper oxide microelectrode for glucose in Example 1 of the present invention.

[0054] Among them, Figure 5 (a) is a comparative CV response curve graph of the bare microchip electrode (bareME), copper microelectrode (Cu-Au ME), and copper oxide microelectrode (CuO-AuME) in Example 1 for 0.1 mM glucose;

[0055] Figure 5 (b) is the current response curve graph of the bare microchip electrode in Example 1 for the blank base solution and 0.1 mM glucose; Figure 5 (c) is the current response curve graph of the copper microelectrode in Example 1 for the blank base solution and 0.1 mM glucose; Figure 5 (d) is the current response curve graph of the copper oxide microelectrode in Example 1 for the blank base solution and 0.1 mM glucose. Referring to Figure 5 It can be seen that compared with the bare microchip electrode and the copper microelectrode, the oxidation peak current of the copper oxide microelectrode for glucose is obvious, and its oxidation potential is about +0.60 V.

[0056] Test Example 2:

[0057] In order to investigate the anti-interference ability, stability, and repeatability of the hemispherical copper oxide microelectrode in Example 1 during glucose detection, the packaged electrode corresponding to the copper oxide microelectrode in Example 1 was also placed in a three-electrode system as the working electrode. 10 mL of 0.1 mol / L PBS solution was placed in the electrolytic cell, and a certain anodic potential was applied to the working electrode for electrochemical scanning, and the current-time curve was recorded. The results are as Figure 6 shown, Figure 6 is the anti-interference ability, stability, and repeatability test graph of the copper oxide microelectrode in Example 1 of the present invention during glucose detection.

[0058] Among them, to investigate the influence of possible non-carbohydrate interferents on glucose detection, the rotation speed was controlled at 250 rpm, and 0.1 mM glucose (glucose), 0.1 mM NaCl, 0.1 mM KCl, 0.1 mM uric acid (UA), 0.1 mM NaH 2 PO 4 , 0.1 mM ascorbic acid (AA), 0.1 mM urea (urea), 0.1 mM sodium citrate (sodiumcitrate), and 0.1 mM glucose (glucose) were successively added to 10 mL of 0.1 mol / L PBS solution every 100 s, and the response value of the current each time was calculated. The results are as Figure 6 (a) shown, Figure 6(a) is the real-time response curve of the copper oxide microelectrode described in Example 1 to non-carbohydrate interferents during glucose detection. Referring to Figure 6 (a), it can be seen that the interference current of the above non-carbohydrate interferents can be ignored, indicating that the copper oxide microelectrode described in the present invention has good anti-interference ability to these non-carbohydrate interferents.

[0059] To investigate the influence of possible carbohydrate interferents on glucose detection, the rotation speed was controlled at 250 rpm. In 10 mL of 0.1 mol / L PBS solution, 0.2 mM glucose, 0.1 mM sucrose, 0.1 mM fructose, 0.1 mM lactose and 0.2 mM glucose were added in sequence, and the response value of the current was calculated each time. The results are as Figure 6 (b) shown. Figure 6 (b) is the real-time response curve of the copper oxide microelectrode described in Example 1 to carbohydrate interferents during glucose detection. Referring to Figure 6 (b), it can be seen that the interference current of the above carbohydrate interferents can be ignored, indicating that the copper oxide microelectrode described in the present invention has good anti-interference ability to these carbohydrate interferents.

[0060] To investigate the stability of the copper oxide microelectrode described in Example 1 during glucose detection, with a cycle of 17 days, the response current value of glucose was detected every 3 days. Specifically, in 10 mL of 0.1 mmol / L PBS solution, a blank potential scan from -0.2 to 0.8 V was carried out by means of an electrochemical workstation using CV. Then glucose was added to the electrolytic cell with a concentration of 0.5 mM. After stirring evenly, CV test was carried out, and the obtained current values were plotted as a bar chart. The results are as Figure 6 (c) shown. Figure 6 (c) is the result chart of the response values of the copper oxide microelectrode described in Example 1 to the same concentration of glucose at the same interval days. Referring to Figure 6 (c), it can be seen that the response values of the same copper oxide microelectrode to the same concentration of glucose are very close every 3 days, indicating that the difference in the current values obtained by testing the same copper oxide microelectrode is not large, and the stability and repeatability of the copper oxide microelectrode described in the present invention are relatively good.

[0061] Test Example 3:

[0062] The packaged electrode corresponding to the hemispherical copper oxide microelectrode described in Example 1 was also placed in a three-electrode system as the working electrode and subjected to electrochemical scanning. When measuring glucose, the three-electrode system was placed in 10 mL of 0.1 mol / L phosphate buffer solution (PBS) aqueous solution. Then, a certain anodic potential was applied to the working electrode, and the current-time curve was recorded. When the background current reached a steady state, under the condition of continuous stirring at a rotation speed of 250 rpm, a glucose standard solution was added to the 10 mL of 0.1 mol / L PBS solution every 100 s, and the concentration range was from 5 μM to 4020 μM. A linear relationship curve between time current and glucose concentration was obtained. The results are as follows Figure 7 shown Figure 7 This is the time-current curve graph of the copper oxide microelectrode described in Example 1 of the present invention for different concentrations of glucose. Among them, Figure 7 (a) Time-current curve graph of the copper oxide microelectrode described in Example 1 for different concentrations of glucose within 0 - 1800 s. The inset is the enlarged current curve graph of the copper oxide microelectrode described in Example 1 for different concentrations of glucose within 0 - 800 s; Figure 7 (b) Current calibration curve graph of the copper oxide microelectrode described in Example 1 at the corresponding glucose concentration (0 - 4020 μM).

[0063] Referring to Figure 7 (a), it can be seen that the copper oxide microelectrode described in Example 1 produced a good amperometric response within a short response time, with characteristics such as a large linear range and good detection effect; referring to Figure 7 (b), it can be seen that it is based on Figure 7 (a) The relationship between the current response and the glucose concentration was linearly fitted for the obtained current-time curve. The linear relationship between the glucose concentration and the response current is y = 0.0034x + 1.1, that is, when the linear range of the copper oxide microelectrode is 5 - 4020 μM, the sensitivity can reach 340 μA·μM -1 ·cm -2 , and the actual detection limit is as low as 0.986 μM, that is, the detection sensitivity is high. The copper oxide microelectrode described in the present invention is of great significance for the detection of trace glucose.

[0064] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. Application of a chip - type hemispherical copper oxide micro - electrode, Characterized in that, The copper oxide micro - electrode is used in a non - enzymatic glucose sensor; The copper oxide micro - electrode comprises nano - copper and nano - copper oxide that are in - situ grown and stacked on a conductive substrate to form a semi - microsphere; wherein, the surface layer of the semi - microsphere is formed by stacking the nano - copper oxide; The size of the semi - microsphere is 2 - 20 μm, and the thickness of the surface layer of the semi - microsphere is 50 - 500 nm; The chip - type hemispherical copper oxide micro - electrode is prepared by the following method: Electrochemical deposition is used to in - situ grow and stack nano - copper on a conductive substrate to form a semi - microsphere, and then further through oxidation heat treatment, the nano - copper on the surface layer of the semi - microsphere is in - situ oxidized to copper oxide, thus obtaining the copper oxide micro - electrode; The electrochemical deposition method specifically includes: Using a bare micro - chip electrode as the working electrode, a divalent copper salt solution as the electrolyte solution, and carrying out potentiostatic deposition under the cooperation of a counter - electrode and a reference electrode, that is, in - situ growing and stacking nano - copper on the working electrode to form a semi - microsphere; wherein, the bare micro - chip electrode comprises a gold conductive substrate and a silica thin film located on the gold conductive substrate and having an open microporous structure.

2. The application of the chip - type hemispherical copper oxide micro - electrode according to claim 1, Characterized in that, The size of the semi - microsphere is 5 μm.

3. The application of the chip - type hemispherical copper oxide micro - electrode according to claim 1, Characterized in that, The diameter of the open micropore is 2 - 10 μm.

4. The application of the chip - type hemispherical copper oxide micro - electrode according to claim 1, Characterized in that, The electrolyte solution further includes a perchlorate solution.

5. The application of the chip - type hemispherical copper oxide micro - electrode according to claim 1, Characterized in that, The electrolyte solution specifically includes a CuSO solution with a concentration of 0.5 - 1.5 mmol / L 4 and a NaClO solution with a concentration of 5 - 15 mmol / L 4 solution.

6. The application of the chip - type hemispherical copper oxide micro - electrode according to claim 1, Characterized in that, The voltage of the potentiostatic deposition is constantly - (0.3 - 0.5) V, and the deposition time is 5 - 75 s.

7. The application of the chip - type hemispherical copper oxide micro - electrode according to claim 1, Characterized in that, In actual operation, in the electrochemical deposition method, the gold conductive substrate located in the open micropore area of the silica thin film in the bare micro - chip electrode is used as the working area, a silver wire electrode is used as the counter - electrode, after connecting the silver wire electrode and the reference electrode together, then the silver wire electrode is inserted into a capillary tube, and the electrolyte solution is injected into the capillary tube, and then the end of the capillary tube is close to the surface of the working area of the bare micro - chip electrode to carry out potentiostatic deposition.

8. The application of the chip - type hemispherical copper oxide micro - electrode according to claim 1, Characterized in that, The temperature of the oxidation heat treatment is 200 - 300 °C, and the time is 3 - 8 min.

9. The application of the chip - type hemispherical copper oxide micro - electrode according to claim 1, Characterized in that, In the enzyme-free glucose sensor, the detection sensitivity of glucose can reach 340 µA·µM -1 ·cm -2 .

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