Carbon-based composite material loaded with gold nano-glassy carbon electrode and its preparation method and application

Abstract

The present invention discloses a carbon-based composite material loaded with gold nano-glassy carbon electrode and its preparation method and application. The preparation method includes the following steps: pre-treating a multi-walled carbon nanotube material; adding the multi-walled carbon nanotube material to a graphene oxide dispersion and then ultrasonically treating it to obtain a MWCNTs-GO composite material dispersion; polishing the glassy carbon electrode and applying the MWCNTs-GO composite material dispersion dropwise onto the glassy carbon electrode and then drying it to obtain a MWCNTs-GO-GCE electrode; reducing the MWCNTs-GO-GCE electrode to a MWCNTs-RGO-GCE electrode by a current-time method; and modifying the MWCNTs-RGO-GCE electrode with a gold nanomaterial to obtain a carbon-based composite material loaded with gold nano-glassy carbon electrode. The present invention solves the problems of poor current response, low yield, and insufficient electrochemical performance of glassy carbon electrodes in the related art.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical technology, and in particular relates to a carbon-based composite material loaded with gold nano-glassy carbon electrode, and a preparation method and application thereof. Background Art

[0002] In recent years, food safety testing has garnered increasing attention. Nitrite, a recognized carcinogen by the World Health Organization, is a crucial component of food safety testing. Among the various methods currently available for detecting nitrite in food, electrochemical methods are the most commonly used due to their simplicity, low cost, speed, directness, and efficiency. However, since these electrochemical sensors utilize bare electrodes and require a higher applied potential, their application scenarios are significantly limited.

[0003] To this end, electrochemical sensors currently typically use carbon-based materials as modification carriers for chemical modification. However, the uneven coverage of carbon-based composite materials on the electrode surface will occupy the binding sites on the electrode surface, affecting the electrode's current response performance. At the same time, when gold nanoparticles are modified on the surface of graphene flexible electrodes, they will exhibit uneven size, uneven arrangement, and agglomeration, affecting the electrocatalytic performance of the finished product and the contact area between the electrode and the detected object, resulting in insufficient electrochemical performance and catalytic activity of the gold nanoparticle-modified electrode.

[0004] In order to solve the problems of poor current response, low yield and insufficient electrochemical performance in the production of carbon-based material loaded gold nano-modified glassy carbon electrodes, a carbon-based composite material loaded gold nano-glassy carbon electrode and its preparation method and application are proposed. Summary of the Invention

[0005] The embodiments of the present invention propose a carbon-based composite material loaded with gold nano-glassy carbon electrode and its preparation method and application, so as to at least solve the problems of poor current response, low yield and insufficient electrochemical performance in the production of glassy carbon electrodes in related technologies.

[0006] According to one embodiment of the present invention, a method for preparing a carbon-based composite material loaded with gold nano-glassy carbon electrodes is provided, comprising:

[0007] Pre-treating multi-walled carbon nanotube materials;

[0008] Multi-walled carbon nanotubes were added to graphene oxide dispersion and then ultrasonically treated to obtain MWCNTs-GO composite dispersion.

[0009] The glassy carbon electrode was polished and the MWCNTs-GO composite material dispersion droplets were applied onto the glassy carbon electrode and then dried to obtain the MWCNTs-GO-GCE electrode;

[0010] The MWCNTs-GO-GCE electrode was reduced to the MWCNTs-RGO-GCE electrode by the current-time method;

[0011] Gold nanomaterials were used to modify the MWCNTs-RGO-GCE electrode to obtain a carbon-based composite material loaded with gold nanoglassy carbon electrode.

[0012] In an exemplary embodiment, the pretreatment of the multi-walled carbon nanotube material comprises the steps of:

[0013] Weigh a set weight of multi-walled carbon nanotube material MWCNTs and dissolve it in hydrochloric acid solution;

[0014] The hydrochloric acid solution containing MWCNTs is ultrasonically dispersed for a set time;

[0015] The ultrasonically dispersed solution is filtered, washed, and air-dried to obtain the pretreated MWCNTs material.

[0016] In an exemplary embodiment, the step of adding a multi-walled carbon nanotube material to a graphene oxide dispersion and then ultrasonically treating the dispersion to obtain a MWCNTs-GO composite material dispersion comprises the following steps:

[0017] Take a set dose of graphene oxide dispersion, dilute it with water and then perform ultrasonic dispersion;

[0018] The pretreated MWCNTs material was weighed according to the set mass ratio of graphene oxide to multi-walled carbon nanotubes and added to the graphene oxide dispersion;

[0019] The mixed solution was ultrasonically dispersed to obtain a MWCNTs-GO composite material dispersion.

[0020] In an exemplary embodiment, the process of polishing the glassy carbon electrode and applying the dispersed MWCNTs-GO composite material droplets onto the glassy carbon electrode and then drying to obtain the MWCNTs-GO-GCE electrode comprises the following steps:

[0021] The bare glassy carbon electrode was polished using aluminum oxide polishing powder;

[0022] The polished glassy carbon electrode was placed in hydrochloric acid solution and deionized water for ultrasonic treatment for a set time;

[0023] The glassy carbon electrode after ultrasonic treatment was taken out, washed and dried with nitrogen gas;

[0024] A set amount of MWCNTs-GO composite material dispersion droplet was drawn and applied onto the treated glassy carbon electrode;

[0025] MWCNTs-GO-GCE electrodes were obtained by infrared drying.

[0026] In an exemplary embodiment, before the step of reducing the MWCNTs-GO-GCE electrode to the MWCNTs-RGO-GCE electrode by the current-time method, the step of detecting whether the MWCNTs-GO-GCE electrode structure is qualified is further included, including:

[0027] Obtaining information about the MWCNTs-GO-GCE electrode surface, including MWCNTs-GO material coverage, flatness, and particle size;

[0028] Calculating a coverage indicator value based on the MWCNTs-GO material coverage thickness and / or the MWCNTs-GO material coverage completeness on the surface of the MWCNTs-GO-GCE electrode;

[0029] The modification effect indicator value is calculated based on the smoothness and / or particle size of the MWCNTs-GO-GCE electrode surface;

[0030] The adsorption effect indicator value was calculated based on the specific surface area and / or adsorption capacity of the MWCNTs-GO-GCE electrode;

[0031] Calculate the qualification of the MWCNTs-GO-GCE electrode structure according to the coverage indicator value and / or the modification effect indicator value and / or the adsorption effect indicator value;

[0032] If the qualification degree of the MWCNTs-GO-GCE electrode structure is greater than the set qualification threshold, the MWCNTs-GO-GCE electrode structure is determined to be qualified; otherwise, the MWCNTs-GO-GCE electrode structure is determined to be unqualified, and the process returns to the step of polishing the glassy carbon electrode and applying the MWCNTs-GO composite material dispersion droplets onto the glassy carbon electrode and then drying it to obtain the MWCNTs-GO-GCE electrode.

[0033] In an exemplary embodiment, the reducing the MWCNTs-GO-GCE electrode to the MWCNTs-RGO-GCE electrode by the current-time method comprises the steps of;

[0034] The MWCNTs-GO-GCE electrode was placed in PBS buffer solution and scanned at a constant potential of -1.2 V;

[0035] During the scanning process, the graphene oxide on the electrode was reduced to obtain the MWCNTs-RGO-GCE electrode.

[0036] In an exemplary embodiment, the method of modifying the MWCNTs-RGO-GCE electrode with gold nanomaterials to obtain a carbon-based composite material loaded with gold nano-glassy carbon electrode comprises the following steps:

[0037] The MWCNTs-RGO-GCE electrode was placed in a pre-prepared chloroauric acid solution;

[0038] The carbon-based composite material loaded with gold nano-glassy carbon electrode was obtained by cyclic voltammetry from -1.3V to 0.8V.

[0039] In an exemplary embodiment, the step of testing the catalytic activity of the carbon-based composite material-loaded gold nano-glassy carbon electrode on nitrite is further included, comprising the steps of:

[0040] Obtain information on the electroactive sites of the gold nanoglassy carbon electrode loaded with carbon-based composite materials, the charge transfer resistance on the electrode surface, and the contact area between the electrode surface and the test object;

[0041] Differential pulse voltammetry was used to obtain the current response values ​​of the carbon-based composite material loaded gold nano-glassy carbon electrode to different concentrations of nitrite;

[0042] The detection performance index of nitrite is calculated based on the concentration of nitrite and its current response value;

[0043] Calculating the electrode catalytic performance index based on the electroactive site information of the gold nano-glassy carbon electrode loaded with the carbon-based composite material and / or the charge transfer resistance on the electrode surface and / or the contact area between the electrode surface and the test object;

[0044] Calculating an electrode catalytic activity evaluation value based on a nitrite detection performance index and / or an electrode catalytic performance index;

[0045] If the electrode catalytic activity evaluation value is greater than the set catalytic activity threshold, it is determined that the catalytic activity of the carbon-based composite material loaded with gold nano-glassy carbon electrode meets the requirements; otherwise, it is determined that the catalytic activity of the carbon-based composite material loaded with gold nano-glassy carbon electrode does not meet the requirements, and the process returns to step: using gold nanomaterials to modify the MWCNTs-RGO-GCE electrode to obtain a carbon-based composite material loaded with gold nano-glassy carbon electrode.

[0046] According to yet another embodiment of the present invention, a gold nanoparticle-modified flexible electrode prepared by the above preparation method is also provided.

[0047] According to another embodiment of the present invention, an application of a carbon-based composite material loaded with gold nano-glassy carbon electrode is provided, and an electrochemical sensor for detecting nitrite content is prepared using the carbon-based composite material loaded with gold nano-glassy carbon electrode as described above.

[0048] The advantages of the carbon-based composite material loaded with gold nano-glassy carbon electrode and its preparation method and application are as follows:

[0049] (1) By loading electrodes with a composite material of multi-walled carbon nanotubes and graphene oxide and modifying gold nanomaterials with this, compared with the traditional electrochemical sensor electrode preparation method, not only can the specific surface area of ​​the electrode be effectively increased to facilitate better attachment of gold nanoparticles, but the modified electrode particles are more uniform in size and more evenly distributed without the occurrence of agglomeration lines, which effectively improves the yield rate.

[0050] (2) The qualification of the MWCNTs-GO-GCE electrode structure is calculated based on the coverage indicator value and / or modification effect indicator value and / or adsorption effect indicator value of the carbon-based composite material on the electrode, and this is used to detect whether the MWCNTs-GO-GCE electrode structure is qualified. Compared with the traditional technical solution of using a fixed reaction time, it can effectively ensure the modification and adsorption effect of the carbon-based composite material on the electrode and improve the yield of the electrode.

[0051] (3) The electrode catalytic performance index is calculated based on the electroactive site information of the carbon-based composite material loaded gold nano-glassy carbon electrode and / or the charge transfer resistance on the electrode surface and / or the contact area between the electrode surface and the test object, and the electrode performance is tested based on this. Compared with the traditional technical solution of using a fixed cycle time to make electrodes, the electrochemical performance and yield of the carbon-based composite material loaded gold nano-glassy carbon electrode can be effectively guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a flow chart of a method for preparing a carbon-based composite material loaded with gold nano-glassy carbon electrode according to an embodiment of the present invention;

[0053] Figure 2 is a method flow chart of step S01 of an embodiment of the present invention;

[0054] Figure 3 is a flowchart of step S02 of an embodiment of the present invention;

[0055] Figure 4 is a method flow chart of step S03 of an embodiment of the present invention;

[0056] Figure 5 is a method flow chart of additional step S03' in an embodiment of the present invention;

[0057] Figure 6 is a flowchart of step S04 of an embodiment of the present invention;

[0058] Figure 7 is a method flow chart of step S05 of an embodiment of the present invention;

[0059] Figure 8 is a method flow chart of additional step S06 of an embodiment of the present invention;

[0060] Figure 9This is a flow chart of an application method of a carbon-based composite material loaded with gold nano-glassy carbon electrode according to an embodiment of the present invention. DETAILED DESCRIPTION

[0061] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art further understand the invention, but are not intended to limit the present invention in any form. It should be noted that those skilled in the art may make several changes and modifications without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0062] A method for preparing a carbon-based composite material loaded with gold nano-glassy carbon electrode according to an embodiment of the present invention is shown in the flow chart. Figure 1 As shown, the steps include:

[0063] Step S01, pre-treating multi-walled carbon nanotube material;

[0064] Step S02, adding a multi-walled carbon nanotube material to a graphene oxide dispersion and then ultrasonically treating the dispersion to obtain a MWCNTs-GO composite material dispersion;

[0065] Step S03, polishing the glassy carbon electrode and applying a dispersed drop of the MWCNTs-GO composite material onto the glassy carbon electrode and then drying it to obtain a MWCNTs-GO-GCE electrode;

[0066] Step S04, reducing the MWCNTs-GO-GCE electrode to a MWCNTs-RGO-GCE electrode by a current-time method;

[0067] Step S05: using gold nanomaterials to modify the MWCNTs-RGO-GCE electrode to obtain a carbon-based composite material loaded with gold nano-glassy carbon electrode.

[0068] In an exemplary embodiment, the step S01, pre-treating the multi-walled carbon nanotube material, is as follows: Figure 2 As shown, the steps include:

[0069] Step S011, weighing a set weight of multi-walled carbon nanotube material MWCNTs and dissolving it in a hydrochloric acid solution;

[0070] Step S012, performing ultrasonic dispersion on the hydrochloric acid solution containing MWCNTs for a set time;

[0071] Step S013: filtering and washing the ultrasonically dispersed solution, and drying the solution to obtain the pretreated MWCNTs material.

[0072] The mass of MWCNTs is 100-200 mg, and 40-80 mL of 6.0 M hydrochloric acid is used. In this example, 150 mg of MWCNTs were weighed and dispersed in 60 mL of 6.0 M hydrochloric acid solution. The dispersed MWCNTs were ultrasonically dispersed, filtered through filter paper, and washed with deionized water. Finally, the MWCNTs were air-dried at room temperature to obtain pretreated MWCNTs.

[0073] In an exemplary embodiment, the step S02 is to add the multi-walled carbon nanotube material to the graphene oxide dispersion and then ultrasonically treat it to obtain a MWCNTs-GO composite material dispersion, as shown in the flow chart. Figure 3 As shown, the steps include:

[0074] Step S021: taking a set dose of graphene oxide dispersion, adding water to dilute it, and then performing ultrasonic dispersion;

[0075] Step S022: weighing the pretreated MWCNTs material according to the set mass ratio of graphene oxide to multi-walled carbon nanotubes and adding it to the graphene oxide dispersion;

[0076] Step S023: ultrasonically disperse the mixed solution to obtain a MWCNTs-GO composite material dispersion.

[0077] The volume ratio of GO to deionized water is 1-3:1-3; the mass ratio of GO to MWCNTs is 5-10:1-2; and the ultrasonication time is 1-2 hours. In this example, 2.5 mL of a 2.0 mg / mL GO dispersion was diluted with 2.5 mL of water to a 1.0 mg / mL GO dispersion, which was then ultrasonically dispersed for 1 hour. Subsequently, 1.0 mg of the treated MWCNTs was added to the GO dispersion and ultrasonically dispersed again for 1 hour to obtain a MWCNTs-GO composite dispersion.

[0078] In an exemplary embodiment, the step S03 is to polish the glassy carbon electrode and apply the MWCNTs-GO composite material dispersion droplets onto the glassy carbon electrode and then dry it to obtain the MWCNTs-GO-GCE electrode. The flow chart is as follows: Figure 4 As shown, the steps include:

[0079] Step S031: polishing the bare glassy carbon electrode using aluminum oxide polishing powder;

[0080] Step S032: placing the polished glassy carbon electrode in a hydrochloric acid solution and deionized water for ultrasonic treatment for a set time;

[0081] Step S033, taking out the glassy carbon electrode after ultrasonic treatment, washing it and blowing it dry with nitrogen;

[0082] Step S034, a set amount of MWCNTs-GO composite material dispersion droplets are drawn and applied onto the treated glassy carbon electrode;

[0083] Step S035: using infrared drying to obtain a MWCNTs-GO-GCE electrode.

[0084] In this example, the glassy carbon electrode was polished to a smooth surface using Al2O3. The polished glassy carbon electrode was ultrasonically treated with a hydrochloric acid solution (37%, w / w) and deionized water for 10 minutes, then washed and dried with nitrogen. A 10 μL pipette was used to draw a 6 μL droplet of the MWCNTs-GO composite material dispersion onto the treated glassy carbon electrode, which was then dried under an infrared lamp to obtain a MWCNTs-GO-GCE electrode.

[0085] In an exemplary embodiment, before step S04, step S03' is further included to detect whether the MWCNTs-GO-GCE electrode structure is qualified. The flow chart is as follows: Figure 5 As shown, including:

[0086] Step S03'1, obtaining information on the surface of the MWCNTs-GO-GCE electrode, including MWCNTs-GO material coverage information, flatness information, and particle size information;

[0087] Step S03'2, calculating a coverage indicator value according to the MWCNTs-GO material coverage thickness and / or the MWCNTs-GO material coverage completeness on the surface of the MWCNTs-GO-GCE electrode;

[0088] Step S03'3, calculating the modification effect indicator value according to the flatness and / or particle size of the MWCNTs-GO-GCE electrode surface;

[0089] Step S03′4: calculating an adsorption effect indicator value according to the specific surface area and / or adsorption property of the MWCNTs-GO-GCE electrode;

[0090] Step S03′5: calculating the qualification of the MWCNTs-GO-GCE electrode structure according to the coverage indicator value and / or the modification effect indicator value and / or the adsorption effect indicator value;

[0091] Step S03′6: If the qualification of the MWCNTs-GO-GCE electrode structure is greater than the set qualification threshold, the MWCNTs-GO-GCE electrode structure is determined to be qualified; otherwise, the MWCNTs-GO-GCE electrode structure is determined to be unqualified, and the process returns to step S03.

[0092] In this embodiment, the surface information of the MWCNTs-GO-GCE electrode is obtained through a microscopic particle image (such as a scanning electron microscope image SEM) of the surface of the MWCNTs-GO-GCE electrode.

[0093] The calculation of the coverage indicator value based on the MWCNTs-GO material coverage thickness and / or the MWCNTs-GO material coverage integrity on the surface of the MWCNTs-GO-GCE electrode is: calculating the coverage indicator value based on a positive correlation between the MWCNTs-GO material coverage thickness on the surface of the MWCNTs-GO-GCE electrode and the coverage indicator value; calculating the coverage indicator value based on a positive correlation between the MWCNTs-GO material coverage integrity (the coverage integrity is calculated based on the ratio of the coverage area to the electrode surface area) on the surface of the MWCNTs-GO-GCE electrode and the coverage indicator value; calculating the coverage indicator value based on a positive correlation between the MWCNTs-GO material coverage thickness and coverage integrity on the surface of the MWCNTs-GO-GCE electrode and the coverage indicator value, represented by the variable e;

[0094] The calculation of the modification effect indicator value according to the smoothness and / or particle size of the MWCNTs-GO-GCE electrode surface is: calculating the modification effect indicator value according to the positive correlation between the smoothness of the MWCNTs-GO-GCE electrode surface (the smoothness is obtained by detecting the smoothness according to the existing smoothness detection means) and the modification effect indicator value, calculating the modification effect indicator value according to the positive correlation between the particle size of the MWCNTs-GO-GCE electrode surface and the modification effect indicator value, or calculating the modification effect indicator value according to the positive correlation between the smoothness and particle size of the MWCNTs-GO-GCE electrode surface and the modification effect indicator value, represented by the variable w;

[0095] The calculation of the adsorption effect indicator value according to the specific surface area and / or adsorption property of the MWCNTs-GO-GCE electrode is: calculating the adsorption effect indicator value according to the positive correlation between the specific surface area of ​​the MWCNTs-GO-GCE electrode and the adsorption effect indicator value, calculating the adsorption effect indicator value according to the positive correlation between the adsorption property of the MWCNTs-GO-GCE electrode (the adsorption property is calculated based on the adsorption ratio of the electrode to a unit amount of test material) and the adsorption effect indicator value, or calculating the adsorption effect indicator value according to the positive correlation between the specific surface area and adsorption property of the MWCNTs-GO-GCE electrode and the adsorption effect indicator value, represented by the variable y;

[0096] The calculation of the MWCNTs-GO-GCE electrode structure qualification according to the coverage indicator value and / or the modification effect indicator value and / or the adsorption effect indicator value is based on the positive correlation between the coverage indicator value and / or the modification effect indicator value and / or the adsorption effect indicator value and the electrode structure qualification, which is represented by the variable x;

[0097] A1 to A7 in Table A represent different implementation methods for calculating the qualification of the electrode structure. The coverage indicator value e, modification effect indicator value w, and adsorption effect indicator value y in Table A are calculated using the method described in any of the above implementation methods.

[0098] Table A Different ways to calculate the qualification of electrode structure

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105]

[0106] A pass threshold is set based on the accuracy requirements for nitrite detection scenarios. In this embodiment, the pass threshold is set at X = 0.8. The electrode structure pass x is calculated based on any item in Table A. If the electrode structure pass x > X, the resulting MWCNTs-GO-GCE electrode structure is considered pass.

[0107] In an exemplary embodiment, the step S04 is to reduce the MWCNTs-GO-GCE electrode to the MWCNTs-RGO-GCE electrode by the current-time method, as shown in the flow chart. Figure 6 As shown, the steps include:

[0108] Step S041, placing the MWCNTs-GO-GCE electrode in a PBS buffer solution and scanning at a constant potential of -1.2 V;

[0109] Step S042: During the scanning process, the graphene oxide on the electrode is reduced to obtain a MWCNTs-RGO-GCE electrode.

[0110] In this example, the dried MWCNTs-GO-GCE electrode was placed in 10 mL of PBS buffer solution with a pH of 4.1 and scanned at a constant potential of -1.2 V for 200 s to reduce the graphene oxide on the MWCNTs-GO-GCE electrode to obtain a MWCNTs-RGO-GCE modified electrode.

[0111] In an exemplary embodiment, the step S05, using gold nanomaterials to modify the MWCNTs-RGO-GCE electrode to obtain a carbon-based composite material loaded with gold nano-glassy carbon electrode, is as shown in the flow chart. Figure 7 As shown, the steps include:

[0112] Step S051, placing the MWCNTs-RGO-GCE electrode into a pre-prepared chloroauric acid solution;

[0113] Step S052: Cyclic voltammetry is used to scan from -1.3 V to 0.8 V to obtain a carbon-based composite material loaded with gold nano-glassy carbon electrode.

[0114] CV electrodeposition parameters: 0.5-1.0 mM chloroauric acid in sodium chloride solution, scan voltage: -1.3-0.8 V, scan rate: 30-60 mV / s, and scan number: 3-7 cycles. In a preferred embodiment, 0.1 mL of 50 mM HAuCl4 solution and 10 mL of 0.5 M NaCl are prepared to form a 0.5 mM HAuCl4 solution. The MWCNTs-RGO-GCE electrode is then placed in a 10 mL, 0.5 mM HAuCl4 solution on an electrochemical platform and cyclically scanned from -1.3-0.8 V for 4 cycles (or 5, 6, or 7 cycles) at a scan rate of 40 mV / s. Gold nanoparticles are then electrodeposited on the surface of the MWCNTs-RGO-GCE electrode to obtain an Au-MWCNTs-RGO-GCE electrode.

[0115] In an exemplary embodiment, after step S05, the process further includes step S06, testing the catalytic activity of the carbon-based composite material loaded with gold nano-glassy carbon electrode to nitrite, as shown in the flow chart. Figure 8 As shown, the steps include:

[0116] Step S061, obtaining information on the electroactive sites of the carbon-based composite material loaded with gold nano-glassy carbon electrodes, the charge transfer resistance on the electrode surface, and the contact area between the electrode surface and the test object;

[0117] Step S062, using differential pulse voltammetry to obtain current response values ​​of the carbon-based composite material loaded with gold nano-glassy carbon electrode to different concentrations of nitrite;

[0118] Step S063, calculating the nitrite detection performance index according to the nitrite concentration and the current response value;

[0119] Step S064, calculating the electrode catalytic performance index based on the electroactive site information of the carbon-based composite material loaded with gold nano-glassy carbon electrode and / or the charge transfer resistance on the electrode surface and / or the contact area between the electrode surface and the test object;

[0120] Step S065: calculating an electrode catalytic activity evaluation value based on the nitrite detection performance index and / or the electrode catalytic performance index;

[0121] Step S066: If the electrode catalytic activity evaluation value is greater than the set catalytic activity threshold, it is determined that the catalytic activity of the carbon-based composite material loaded gold nano-glassy carbon electrode meets the requirements; otherwise, it is determined that the catalytic activity of the carbon-based composite material loaded gold nano-glassy carbon electrode does not meet the requirements, and the process returns to step S05.

[0122] In this example, the electroactive site information, charge transfer resistance on the electrode surface, and contact area between the electrode surface and the test substance of the Au-MWCNTs-RGO-GCE electrode were obtained by microscopic particle imaging (e.g., scanning electron microscopy (SEM)) and electrocatalytic activity testing of the Au-MWCNTs-RGO-GCE electrode. The current response of the Au-MWCNTs-RGO-GCE electrode to nitrite in the concentration range of 10 to 800 μM was measured using DPV. The DPV test parameters were: buffer solution PBS pH = 4.0 (alternatively pH = 5.0, 6.0, or 7.0), and a scanning voltage range of 0.5 to 1.0 V.

[0123] The detection performance index of nitrite calculated according to the concentration of nitrite and its current response value is calculated according to the concentration of nitrite and its current response value. The detection range of the electrode for nitrite is calculated based on the positive correlation between the detection range and the minimum detection limit and the detection performance index of nitrite. The detection performance index of nitrite is represented by the variable p.

[0124] The electrode catalytic performance index is calculated based on the electroactive site information of the carbon-based composite material-loaded gold nano-glassy carbon electrode and / or the electrode surface charge transfer resistance and / or the contact area between the electrode surface and the test object, which includes: calculating the electrode catalytic performance index based on the positive correlation between the number of electroactive sites of the Au-MWCNTs-RGO-GCE electrode and the electrode catalytic performance index; calculating the electrode catalytic performance index based on the positive correlation between the surface charge transfer resistance of the Au-MWCNTs-RGO-GCE electrode and the electrode catalytic performance index; calculating the electrode catalytic performance index based on the positive correlation between the actual contact area of ​​the Au-MWCNTs-RGO-GCE electrode surface (the actual contact area with the test object) and the electrode catalytic performance index; and calculating the electrode catalytic performance index based on the positive correlation between the actual contact area of ​​the Au-MWCNTs-RGO-GCE electrode surface and the electrode catalytic performance index. -The electrode catalytic performance index is calculated based on the positive correlation between the number of electroactive sites and surface charge transfer resistance of the Au-MWCNTs-RGO-GCE electrode and the electrode catalytic performance index; the electrode catalytic performance index is calculated based on the positive correlation between the number of electroactive sites and the actual contact area of ​​the Au-MWCNTs-RGO-GCE electrode and the electrode catalytic performance index; the electrode catalytic performance index is calculated based on the positive correlation between the surface charge transfer resistance and the actual contact area of ​​the Au-MWCNTs-RGO-GCE electrode and the electrode catalytic performance index; any one of the electrode catalytic performance indicators is calculated based on the positive correlation between the number of electroactive sites and the surface charge transfer resistance and the actual contact area of ​​the Au-MWCNTs-RGO-GCE electrode and the electrode catalytic performance index, and is represented by the variable q.

[0125] The electrode catalytic activity evaluation value calculated based on the nitrite detection performance index and / or the electrode catalytic performance index is calculated based on the positive correlation between the nitrite detection performance index and / or the electrode catalytic performance index and the electrode catalytic activity evaluation value, and is represented by the variable z.

[0126] B1 to B3 in Table B represent different implementation methods for calculating the electrode catalytic activity evaluation value, wherein the nitrite detection performance index p and the electrode catalytic performance index q involved in Table B are obtained using the above implementation methods.

[0127] Table B Different implementation methods for calculating the evaluation value of electrode catalytic activity

[0128]

[0129]

[0130]

[0131]

[0132] The electrode catalytic activity threshold is set based on the scenario for nitrite detection and the requirements for detection accuracy. In this embodiment, the catalytic activity threshold Z is set to 0.8. When the electrode catalytic activity evaluation value obtained according to any item in Table B is greater than the set catalytic activity threshold, it is determined that the catalytic activity performance of the carbon-based composite material-loaded gold nano-glassy carbon electrode meets the requirements, and a carbon-based composite material-loaded gold nano-glassy carbon electrode that meets the requirements has been produced. Otherwise, the process returns to step S05 to continue cyclic voltammetry.

[0133] For comparison, MWCNTs-RGO-GCE electrodes and Au-GCE electrodes were prepared using a procedure similar to that used to prepare Au-MWCNTs-RGO-GCE electrodes. Figure 9 As shown in the figure, the magnitude of the charge transfer resistance on the electrode surface is: Rct(Au-MWCNTs-RGO-GCE)>Rct(MWCNTs-RGO-GCE)>Rct(GCE), indicating that the modified AuNPs and MWCNTs-RGO composite materials have a synergistic effect, which accelerates the electron transfer rate on the Au-MWCNTs-RGO-GCE electrode surface.

[0134] A carbon-based composite material loaded with gold nano-glassy carbon electrode according to an embodiment of the present invention is prepared by the method of any of the above embodiments.

[0135] An application of a carbon-based composite material loaded with gold nano-glassy carbon electrode in an embodiment of the present invention is to use the carbon-based composite material loaded with gold nano-glassy carbon electrode described in any of the above embodiments to make an electrochemical sensor for detecting nitrite content.

[0136] The test results show that the Au-MWCNTs-RGO-GCE sensor has a good linear response to concentrations in the range of 10-800 μM.

[0137] Of course, those skilled in the art should realize that the above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. As long as they are within the scope of the present invention, any changes or modifications to the above embodiments will fall within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon-based composite material loaded with gold nano-glassy carbon electrode, characterized in that: include: Pre-treating multi-walled carbon nanotube materials; Multi-walled carbon nanotubes were added to graphene oxide dispersion and then ultrasonically treated to obtain MWCNTs-GO composite dispersion. The glassy carbon electrode was polished and the MWCNTs-GO composite material dispersion droplets were applied onto the glassy carbon electrode and then dried to obtain the MWCNTs-GO-GCE electrode; Detecting whether the MWCNTs-GO-GCE electrode structure is qualified includes: obtaining information on the surface of the MWCNTs-GO-GCE electrode, including MWCNTs-GO material coverage information, flatness information and particle size information; calculating a coverage indication value based on the MWCNTs-GO material coverage thickness and / or MWCNTs-GO material coverage integrity on the surface of the MWCNTs-GO-GCE electrode; calculating a modification effect indication value based on the flatness and / or particle size of the MWCNTs-GO-GCE electrode surface; calculating a modification effect indication value based on the specific surface area and and / or adsorption calculating an adsorption effect indicator value; calculating the qualification of the MWCNTs-GO-GCE electrode structure according to the coverage indicator value and / or the modification effect indicator value and / or the adsorption effect indicator value; if the qualification of the MWCNTs-GO-GCE electrode structure is greater than a set qualification threshold, the MWCNTs-GO-GCE electrode structure is determined to be qualified; otherwise, the MWCNTs-GO-GCE electrode structure is determined to be unqualified, and the process returns to the step of polishing the glassy carbon electrode and applying a MWCNTs-GO composite material dispersion droplet onto the glassy carbon electrode and then drying to obtain the MWCNTs-GO-GCE electrode; The MWCNTs-GO-GCE electrode was reduced to the MWCNTs-RGO-GCE electrode by the current-time method; Gold nanomaterials were used to modify the MWCNTs-RGO-GCE electrode to obtain a carbon-based composite material loaded with gold nano-glassy carbon electrode; Testing the catalytic activity of a carbon-based composite material loaded with gold nano-glassy carbon electrode for nitrite includes the following steps: obtaining electroactive site information, electrode surface charge transfer resistance, and contact area between the electrode surface and a test object of the carbon-based composite material loaded with gold nano-glassy carbon electrode; obtaining current response values ​​of the carbon-based composite material loaded with gold nano-glassy carbon electrode to different concentrations of nitrite using differential pulse voltammetry; calculating a nitrite detection performance index based on the nitrite concentration and its current response value; calculating an electrode catalytic performance index based on the electroactive site information and / or electrode surface charge transfer resistance and / or contact area between the electrode surface and a test object of the carbon-based composite material loaded with gold nano-glassy carbon electrode; calculating an electrode catalytic activity evaluation value based on the nitrite detection performance index and / or the electrode catalytic performance index; if the electrode catalytic activity evaluation value is greater than a set catalytic activity threshold, determining that the catalytic activity of the carbon-based composite material loaded with gold nano-glassy carbon electrode meets the requirements; otherwise, determining that the catalytic activity of the carbon-based composite material loaded with gold nano-glassy carbon electrode does not meet the requirements, and returning to the step of modifying the MWCNTs-RGO-GCE electrode with gold nanomaterials to obtain a carbon-based composite material loaded with gold nano-glassy carbon electrode.

2. The method for preparing a carbon-based composite material loaded with gold nano-glassy carbon electrode according to claim 1, characterized in that: The pretreatment of multi-walled carbon nanotube material comprises the following steps: Weigh a set weight of multi-walled carbon nanotube material MWCNTs and dissolve it in hydrochloric acid solution; The hydrochloric acid solution containing MWCNTs is ultrasonically dispersed for a set time; The ultrasonically dispersed solution is filtered, washed, and air-dried to obtain the pretreated MWCNTs material.

3. The method for preparing a carbon-based composite material loaded with gold nano-glassy carbon electrode according to claim 1, characterized in that: The method comprises the steps of adding a multi-walled carbon nanotube material to a graphene oxide dispersion and then ultrasonically treating the dispersion to obtain a MWCNTs-GO composite material dispersion. Take a set dose of graphene oxide dispersion, dilute it with water and then perform ultrasonic dispersion; The pretreated MWCNTs material was weighed according to the set mass ratio of graphene oxide to multi-walled carbon nanotubes and added to the graphene oxide dispersion; The mixed solution was ultrasonically dispersed to obtain a MWCNTs-GO composite material dispersion.

4. The method for preparing a carbon-based composite material loaded with gold nano-glassy carbon electrode according to claim 1, characterized in that: The method of polishing the glassy carbon electrode and applying the dispersed liquid of the MWCNTs-GO composite material onto the glassy carbon electrode and then drying the obtained MWCNTs-GO-GCE electrode comprises the following steps: The bare glassy carbon electrode was polished using aluminum oxide polishing powder; The polished glassy carbon electrode was placed in hydrochloric acid solution and deionized water for ultrasonic treatment for a set time; The glassy carbon electrode after ultrasonic treatment was taken out, washed and dried with nitrogen gas; A set amount of MWCNTs-GO composite material dispersion droplet was drawn and applied onto the treated glassy carbon electrode; MWCNTs-GO-GCE electrodes were obtained by infrared drying.

5. The method for preparing a carbon-based composite material loaded with gold nano-glassy carbon electrode according to claim 1, characterized in that: The method of reducing the MWCNTs-GO-GCE electrode to the MWCNTs-RGO-GCE electrode by the current-time method comprises the steps of: The MWCNTs-GO-GCE electrode was placed in PBS buffer solution and scanned at a constant potential of -1.2 V; During the scanning process, the graphene oxide on the electrode was reduced to obtain the MWCNTs-RGO-GCE electrode.

6. The method for preparing a carbon-based composite material loaded with gold nano-glassy carbon electrode according to claim 1, characterized in that: The method of using gold nanomaterials to modify the MWCNTs-RGO-GCE electrode to obtain a carbon-based composite material loaded with gold nano-glassy carbon electrode comprises the following steps: The MWCNTs-RGO-GCE electrode was placed in a pre-prepared chloroauric acid solution; The carbon-based composite material loaded with gold nano-glassy carbon electrode was obtained by cyclic voltammetry from -1.3 V to 0.8 V.

7. A carbon-based composite material loaded with gold nano-glassy carbon electrode, characterized in that: Prepared by the method according to any one of claims 1 to 6.

8. An application of a carbon-based composite material loaded with gold nano-glassy carbon electrode, characterized in that: An electrochemical sensor for detecting nitrite content is prepared by using the carbon-based composite material loaded with gold nano-glassy carbon electrode as claimed in claim 7.

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