Electrocatalytic water hydrogen production catalyst based on hollow shell structure as well as preparation method and application thereof
By preparing hollow shell catalysts with Ir-FeP nanoheterostructures, the problems of high cost and poor conductivity of precious metal catalysts are solved, and efficient and stable electrocatalytic aquatic hydrogen performance is achieved, which is suitable for green hydrogen production.
Patent Information
- Application Number
- CN202510434622.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-08
- Publication Date
- 2025-07-04
AI Technical Summary
The existing precious metal catalysts have high cost, poor conductivity, cumbersome preparation methods, and low hydrogen activity of electrocatalytic aquatic products and poor stability.
The hollow shell structure was prepared by SiO2@C template, and hollow carbon spheres were formed by chemical corrosion, and FeP nanoparticles were loaded and Ir nanoparticles were loaded on their surface by chemical reduction to form Ir-FeP nanoheterostructure catalyst.
The amount of precious metals is reduced, the specific surface area and conductivity of the catalyst is improved, and the catalytic activity and stability are enhanced. The overpotential is only 15.3mV/cm-2 when it is 10mA/cm-2. The stability is more than 48 hours, making it suitable for industrial production.
Smart Images
Figure CN120250058A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of catalysts, and specifically relates to a highly efficient electrocatalytic water splitting hydrogen production catalyst based on a hollow shell structure, its preparation method and application. Background Art
[0002] With the continuous development of industrial production, the environmental problems caused by the combustion of fossil fuels have become increasingly serious, and the development and application of green energy have received great attention. Hydrogen energy is considered to be the best green energy for large-scale replacement of existing fossil fuels due to its non-toxic, pollution-free and high calorific value. The use of hydrogen is also an important means to solve future energy and environmental pollution problems. Electro-catalytic water splitting for hydrogen production is considered to be an effective method for pollution-free and high-efficiency hydrogen production. However, electro-catalytic water splitting hydrogen production catalysts face problems such as low hydrogen production activity and poor stability. Noble metal materials (Pt, Ir) are considered to be highly efficient electrolytic water splitting hydrogen production catalysts. However, due to their low content in the earth and high price, it is difficult to be widely used in industrial hydrogen production. Therefore, how to reduce the amount of noble metals used and thus reduce the price of the catalyst without reducing the catalytic performance of the catalyst has become a challenging topic. Developing high-performance electro-catalytic water splitting hydrogen production catalysts with low noble metal content is of great significance for promoting the development and commercialization process of electro-catalytic seawater preparation of green hydrogen technology. Modifying noble metal catalysts to give full play to their effectiveness has received extensive attention from researchers. One important research direction is to increase the effective active area of noble metal catalysts by loading them on carriers with high specific surface area to reduce their usage. On the other hand, by constructing heterogeneous structures, the adsorption energy of H* intermediate products is optimized to improve hydrogen production activity. The reported modification methods for noble metals at the present stage all have limitations, such as poor conductivity of the catalyst and complex process preparation, which seriously affect the final catalytic activity and stability of the electrode. Summary of the Invention
[0003] Object of the Invention: The technical problem to be solved by the present invention is to provide an electro-catalytic water splitting hydrogen production catalyst with a hollow shell structure modified by an Ir-FeP nano-heterogeneous structure to solve the problems of high cost, poor conductivity and cumbersome preparation method of existing noble metal catalysts.
[0004] Another technical problem to be solved by the present invention is to provide a preparation method for the above electro-catalytic water splitting hydrogen production catalyst.
[0005] The last technical problem to be solved by the present invention is to provide the application of the above electro-catalytic water splitting hydrogen production catalyst.
[0006] Technical Solution: To solve the above technical problems, the present invention adopts the following technical solutions:
[0007] A preparation method of an electrocatalytic water splitting hydrogen production catalyst based on a hollow shell structure. First, prepare a SiO2@C template, remove SiO2 from the SiO2@C to obtain NC, then load FeP nanoparticles on the surface of NC to obtain FeP@NPC, and finally load Ir nanoparticles on the surface of FeP@NPC to obtain the Ir-FeP@NPC electrocatalytic water splitting hydrogen production catalyst.
[0008] Among them, the preparation method of the SiO2@C template is as follows:
[0009] (A1) Preparation of SiO2@PDA: Take SiO2, deionized water, and absolute ethanol and add them to a beaker and ultrasonically treat; add dopamine hydrochloride and NH3·H2O, stir, wash, centrifuge, and dry to obtain SiO2@PDA;
[0010] The preparation method of the SiO2 is as follows: Add 90 ml of absolute ethanol and 8.9 mL of NH3·H2O to a 250 ml beaker and stir for 5 min, denoted as solution A. Add 20 mL of absolute ethanol and 4 mL of tetraethyl orthosilicate to a 50 ml beaker and stir evenly, and drop it into A within 10 min and stir for 4.5 h. Wash, centrifuge the obtained suspension, and dry it in an oven at 60 °C;
[0011] (A2) Preparation of SiO2@C: Heat-treat the dried SiO2@PDA in a tubular furnace under an argon atmosphere to obtain SiO2@C.
[0012] In step (A2), for the heat treatment under an argon atmosphere, the heat treatment temperature is 800 °C and the heat treatment time is 5 h.
[0013] Furthermore, the method for removing SiO2 from SiO2@C is as follows: Take SiO2@C, stir and corrode it in a KOH solution, wash, centrifuge, and dry the corroded suspension to obtain NC.
[0014] Preferably, SiO2@C is corroded and treated in a 6M KOH solution at 80 °C to remove the SiO2 template, the stirring rate of the corrosion reaction is 800 rpm, and the corrosion time is 3.5 h.
[0015] Furthermore, the method for coating FeP nanoparticles on the surface of NC is as follows:
[0016] Preparation of FeP@NC: Dissolve FeCl3 in a mixed solution of deionized water and absolute ethanol and stir, add NC and ultrasonicate, and react; wash, centrifuge, and dry the reaction suspension, and perform phosphating heat treatment in a tubular furnace under an argon atmosphere.
[0017] Preferably, 0.3244 g of FeCl3 is dissolved in a mixed solution of 20 ml of deionized water and 20 ml of absolute ethanol and stirred for 30 min. 50 mg of NC is added and ultrasonically treated for 5 min, and the reaction is carried out at 50 °C for 3 h with a stirring rate of 800 rpm. It is washed, centrifuged, and dried. In a tubular furnace, an argon atmosphere is introduced, and NaH2PO2 is placed upstream of the argon gas flow and phosphated at 450 °C for 2 h to obtain FeP@NC.
[0018] Furthermore, the method for coating Ir nanoparticles on the surface of NC is as follows:
[0019] Preparation of Ir@NC: 15 mg of IrCl3·3H2O, 3 ml of 0.5 M PAH, and 36 mg of NC are dissolved in 33 ml of deionized water and stirred for 30 min. 2 ml of 1 M NaOH and 3 ml of formaldehyde solution are added and stirred for 30 min, then transferred to a reaction kettle and reacted at 200 °C for 8 h.
[0020] Furthermore, the method for coating Ir nanoparticles on the surface of FeP@NC is as follows:
[0021] Preparation of Ir-FeP@NC: 12 - 18 mg of IrCl3·3H2O, PAH, and FeP@NC are dissolved in deionized water and stirred. NaOH and formaldehyde solution are added, and after stirring, it is transferred to a reaction kettle for hydrothermal reaction. The reaction suspension is washed, centrifuged, and dried to obtain the finished Ir-FeP@NPC electrocatalytic water splitting hydrogen production catalyst.
[0022] Preferably, 15 mg of IrCl3·3H2O, 3 mL of 0.5 M PAH, and 36 mg of FeP@NC are dissolved in 33 ml of deionized water and stirred for 30 min. 2 mL of 1 M NaOH and 3 ml of formaldehyde solution are added and stirred for 30 min, then transferred to a reaction kettle and reacted at 200 °C for 8 h. The reaction suspension obtained after the reaction is washed, centrifuged, and dried to obtain the Ir-FeP@NC electrocatalytic water splitting hydrogen production catalyst.
[0023] The electrocatalytic water splitting hydrogen production catalyst prepared by the above preparation method of the high-efficiency electrocatalytic water splitting hydrogen production catalyst based on the hollow shell structure is within the protection scope of the present invention.
[0024] The application of the above electrocatalytic water splitting hydrogen production catalyst in hydrogen production is within the protection scope of the present invention.
[0025] The preparation method of the electrode material using the Ir-FeP@NC electrocatalytic water splitting hydrogen production catalyst as the raw material is as follows: Take 5 mg of Ir-FeP@NC, 1.5 mg of carbon black, 250 μL of deionized water, 250 μL of absolute ethanol, and 50 μL of 5% Nafion 117 solution, and ultrasonicate for 30 minutes to make a slurry; Take 10 μL of the slurry and drop it on the polished and cleaned glassy carbon electrode, and make the electrode after natural drying.
[0026] Electrochemical performance test:
[0027] The HER performance was analyzed on a CHI 650E electrochemical workstation through a standard three-electrode system. The saturated calomel electrode (SCE) and the platinum sheet were used as the reference electrode and the counter electrode respectively. The working electrode was the glassy carbon electrode (diameter 3 mm) loaded with the catalyst. All electrode potentials (relative to SCE) were calibrated with respect to the reversible hydrogen electrode (RHE) and IR correction (solution resistance) was performed, that is, E (RHE) = E (SCE) + 0.244 + (0.0599 × pH) - i Rs (at 25 °C). The linear sweep voltammetry (LSV) rate was 5 mV s -1 , Ir-FeP@NC, FeP@NC, Ir@NC, NC, and the high-purity Pt sheet were all tested in 0.5 M H2SO4 electrolyte. The voltage used for measuring chronoamperometry was 18.4 mV / cm -2 .
[0028] Beneficial effects: Compared with the prior art, the present invention has the following advantages:
[0029] (1) In the method for preparing the hollow shell catalyst of the present invention, the SiO2@PDA template is first prepared, and then the precursor of the FeP nanoparticles is attached to the surface of the SiO2@PDA template by a simple stirring method, and the two components are stably combined through subsequent phosphidation reaction. At the same time, the Ir nanoparticles are stably reduced near the synthesized FeP nanoparticles by a chemical reduction method to form a nanoheterostructure, increasing the stability during the catalyst reaction process.
[0030] (2) The present invention uses the SiO2@C template, and then forms a hollow shell structure through template corrosion, and then coats FeP and Ir nanoparticles on its surface. Through the hollow shell structure, the specific surface area of the catalyst is increased, the amount of Ir noble metal used is reduced, and high activity for catalytic hydrogen evolution is achieved at the same time, effectively solving the contradiction between the cost and performance of the Ir-based catalyst, which is of great significance for the problems existing in the current green hydrogen production.
[0031] (3) The FeP nanoparticles and Ir nanoparticles used in the present invention form a synergistic effect, optimizing the adsorption energy between the H* intermediate product and the active site, and improving the hydrogen evolution activity of the catalyst. Therefore, the prepared shell structure has high catalytic activity.
[0032] (4) The hollow shell structure synthesized in the present invention effectively promotes the transfer of electrons during the hydrogen evolution reaction, improves the conductivity of the catalyst, and further improves the hydrogen evolution activity.
[0033] (5) The synthesized electrocatalyst Ir-FeP@NC has high-efficiency hydrogen evolution performance. Under the premise that the overcurrent density is 10 mA / cm -2 , the overpotential in acidic solution is 15 mV / cm -2 , which is almost the same as that of high-purity flaky Pt.
[0034] (6) The preparation of the catalyst in the present invention has a simple process, a short production cycle, and easy control of reaction conditions, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Figure 1 SEM image of SiO2 microsphere template.
[0036] Figure 2 SEM image of NC hollow shell structure.
[0037] Figure 3 SEM image of FeP@NC hollow shell structure.
[0038] Figure 4 SEM image of Ir@NC hollow shell structure.
[0039] Figure 5 SEM image of Ir-FeP@NC hollow shell structure.
[0040] Figure 6 TEM image of FeP@NC hollow shell structure.
[0041] Figure 7 TEM image of Ir@NC hollow shell structure.
[0042] Figure 8 TEM image of Ir-FeP@NC hollow shell structure.
[0043] Figure 9 Electrocatalytic hydrogen evolution polarization curve diagrams of Ir-FeP@NC, FeP@NC, Ir@NC, NC and Pt.
[0044] Figure 10 Electrocatalytic hydrogen evolution polarization curve diagrams of Ir-FeP@NC-12, Ir-FeP@NC-15, Ir-FeP@NC-18.
[0045] Figure 11 Stability test of Ir-FeP@NC. Specific implementation mode
[0046] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.
[0047] Example 1: Preparation of electrolytic water hydrogen production catalyst.
[0048] (1) Preparation of SiO2: Anhydrous ethanol and NH3·H2O were added to a beaker and stirred, denoted as solution A. Anhydrous ethanol and tetraethyl orthosilicate were added to a beaker and stirred evenly, and then dropped into solution A drop by drop. After stirring, it was washed, centrifuged, and dried.
[0049] (2) Preparation of SiO2@PDA: 100 mg of SiO2, 20 ml of deionized water, and 80 ml of anhydrous ethanol were mixed and ultrasonically treated for 15 min; 200 mg of dopamine hydrochloride and 1 ml of NH3·H2O were added and stirred at 40 °C and 1000 rpm for 5 h. Through washing, centrifugation, and drying, SiO2@PDA powder was obtained.
[0050] (3) Preparation of NC: The dried SiO2@PDA was heat-treated in a tubular furnace under an argon atmosphere at 800 °C for 5 h. The obtained heat-treated product was corroded in 6 M KOH solution at 80 °C to remove the SiO2 template. The stirring rate of the corrosion reaction was 800 rpm, and the corrosion time was 3.5 h. The suspension obtained from the reaction was washed, centrifuged, and dried.
[0051] (4) Preparation of FeP@NC: 0.3244 g of FeCl3 was dissolved in a mixed solution of 20 ml of deionized water and 20 ml of anhydrous ethanol and stirred for 30 min (the beaker mouth was sealed with a sealing film). 50 mg of NC was added and ultrasonically treated for 5 min, and the reaction was carried out at 50 °C for 3 h with a stirring rate of 800 rpm. It was washed, centrifuged, and dried. In a tubular furnace, an argon atmosphere was introduced, and NaH2PO2 was placed upstream of the argon flow and phosphated at 450 °C for 2 h to obtain the sample FeP@NC.
[0052] (5) Preparation of Ir@NC: 15 mg of IrCl3·3H2O, 3 ml of 0.5 M PAH (poly(allylamine·hydrochloride)), and 36 mg of NC were dissolved in 33 ml of deionized water and stirred for 30 min. 2 ml of 1 M NaOH and 3 ml of formaldehyde solution were added and stirred for 30 min, and then transferred to a reaction kettle and reacted at 200 °C for 8 h.
[0053] (6) Preparation of Ir-FeP@NC (Ir-FeP@NC-12, Ir-FeP@NC-15, Ir-FeP@NC-18): Dissolve 12 mg, 15 mg, and 18 mg of IrCl3·3H2O, 3 mL of 0.5 M PAH (poly(allylamine hydrochloride)), and 36 mg of FeP@NC in 33 mL of deionized water and stir for 30 min. Add 2 mL of 1 M NaOH and 3 mL of formaldehyde solution, stir for 30 min, transfer to a reaction kettle, and react at 200 °C for 8 h. Wash, centrifuge, and dry the resulting suspension after the reaction to obtain the catalysts Ir-FeP@NC-12, Ir-FeP@NC-15, and Ir-FeP@NC-18.
[0054] The SEM image of the SiO2 nanoparticle template synthesized in step (1) is as Figure 1 shown. The particles are uniform, the surface is smooth, and the size is about 200 nm.
[0055] The SEM image of the NC hollow shell structure synthesized in step (3) is as Figure 2 shown. The surface is smooth, the size is about 200 nm, and there is a hollow cavity structure in the middle.
[0056] The SEM images of the FeP@NC and Ir@NC hollow shell structures synthesized in steps (4) and (5) are as Figure 3 and Figure 4 shown. The surface is rough, loaded with nanoparticles, and the loaded nanoparticles are evenly distributed. The center of the sphere is a hollow structure, and the size is about 300 nm.
[0057] The SEM image of the Ir-FeP@NC hollow shell structure synthesized in step (6) is as Figure 5 shown. The surface is uneven, but the center of the sphere is still a hollow structure. Compared with the NC hollow shell, the Ir-FeP@NC hollow shell grows slightly larger, and the size is about 300 nm.
[0058] The TEM images of the FeP@NC and Ir@NC hollow shell structures synthesized in step (4) are as Figure 6 and Figure 7 shown. The surface is loaded with nanoparticles, the catalyst is a hollow structure, and the size is about 300 nm.
[0059] The SEM image of the Ir-FeP@NC hollow shell structure synthesized in step (6) is as Figure 8 shown. The center of the sphere is still a hollow structure, the size is about 230 nm, and there are nanoparticles loaded on the surface of the hollow shell.
[0060] Example 2: Hydrogen evolution reaction test.
[0061] The hydrogen evolution reaction test adopted a three-electrode test system, that is, a carbon rod was used as the counter electrode, Ag / AgCl was used as the reference electrode, and a glassy carbon electrode was used as the working electrode to test the performance using a three-electrode system. Specifically, Ir-FeP@NC (Ir-FeP@NC-12, Ir-FeP@NC-15, Ir-FeP@NC-18), FeP@NC, Ir@NC, NC, and Pt / C were loaded onto the glassy carbon electrode.
[0062] The method of loading the catalyst material onto the glassy carbon electrode was as follows: Take 5 mg of Ir-FeP@NC, 1.5 mg of carbon black, 250 μL of deionized water, 250 μL of absolute ethanol, and 50 μL of a 5% mass fraction Nafion 117 solution, and ultrasonicate for 30 minutes to make a slurry; Take 10 μL of the slurry and drop it onto the polished and cleaned glassy carbon electrode, and make the electrode after natural drying. The linear sweep voltammetry (LSV) test used for the HER test was carried out in this electrolyte, and the scan rate was 5 mV / s.
[0063] As Figure 9 、 10 shown are the hydrogen evolution reaction polarization curves of Ir-FeP@NC, FeP@NC, and Ir@NC. Among them, Pt has the best electrocatalytic hydrogen production activity. Under the condition of a current density of 10 mA / cm -2 , the overpotential is 10.2 mV / cm -2 , NC hardly has electrocatalytic hydrogen evolution activity. This result proves that the activity of the synthesized catalyst originates from Ir and FeP nanoparticles, rather than the NC hollow shell. Among the synthesized catalysts, the overpotentials of Ir-FeP-12@NC, Ir-FeP-15@NC, and Ir-FeP-18@NC are 48.6 mV / cm -2 , 15.3 mV / cm -2 , and 33.9 mV / cm -2 respectively. The overpotential of FeP@NC is 97.8 mV / cm -2 , the overpotential of Ir@NC is 67.2 mV / cm -2 , and the overpotential of Ir-FeP@NC is the smallest, almost equivalent to the hydrogen evolution activity of the Pt sheet, proving that among the synthesized catalysts, Ir-FeP@NC has the strongest catalytic hydrogen evolution activity
[0064] Through electrochemical experiments, the chronoamperometry method was used to test the stability of the catalyst Ir-FeP@NC, as Figure 11 shown. At a stable voltage of 18.4 mV / cm -2 , Ir-FeP@NC can maintain a stable current density for more than 48 h without decline, proving the hydrogen evolution stability of the synthesized Ir-FeP@NC catalyst.
[0065] In summary, it can be seen that the high-efficiency hydrogen evolution catalyst material Ir-FeP@NC of the present invention uses a simple method to load Ir nanoparticles on the hollow carbon shell, increasing the Ir loading amount and exposing more active sites; and by synthesizing a nanoheterostructure of Ir and FeP, the adsorption energy of H* intermediate products is optimized, thereby significantly reducing the overpotential of the catalyst at a certain current density during the HER process and maintaining good stability during the recycling process.
Claims
1. A preparation method of an electrocatalytic water splitting hydrogen production catalyst based on a hollow shell structure, characterized in that: First, prepare the SiO2@C template, remove SiO2 from SiO2@C to obtain NC, then load FeP nanoparticles on the surface of NC to obtain FeP@NPC, and finally load Ir nanoparticles on the surface of FeP@NPC to obtain the Ir-FeP@NPC electrocatalytic water splitting hydrogen evolution catalyst.
2. The preparation method of the electrocatalytic water splitting hydrogen production catalyst based on the hollow shell structure according to claim 1, characterized in that, The preparation method of the SiO2@C template is as follows: (A1) Preparation of SiO2@PDA: Take SiO2, deionized water, and absolute ethanol and add them to a beaker and ultrasonically treat; add dopamine hydrochloride and NH3·H2O, stir, wash, centrifuge, and dry to obtain SiO2@PDA; (A2) Preparation of SiO2@C: Heat-treat the dried SiO2@PDA in a tube furnace at 800 °C for 5 h under an argon atmosphere to obtain SiO2@C.
3. The preparation method of the electrocatalytic water splitting hydrogen production catalyst based on the hollow shell structure according to claim 1, characterized in that, The method for removing SiO2 from SiO2@C is as follows: Take SiO2@C and stir it in a 6 M KOH solution for a corrosion reaction for 3.5 h, wash, centrifuge, and dry the corroded suspension to obtain NC.
4. The preparation method of the electrocatalytic water splitting hydrogen production catalyst based on the hollow shell structure according to claim 1, wherein, The method for loading FeP nanoparticles on the surface of NC is as follows: Preparation of FeP@NC: Dissolve 0.3244 g of FeCl3 in a mixed solution of 20 ml of deionized water and 20 ml of absolute ethanol and stir for 30 min, add 50 mg of NC and ultrasonically treat for 5 min, react at 50 °C for 3 h, with a stirring rate of 800 rpm, wash, centrifuge, and dry; in a tube furnace, introduce an argon atmosphere, place NaH2PO2 upstream of the argon gas flow and phosphorate at 450 °C for 2 h to obtain the sample FeP@NC.
5. The preparation method of the electrocatalytic water splitting hydrogen production catalyst based on the hollow shell structure according to claim 1, wherein, The method for loading Ir nanoparticles on the surface of NC is as follows: Preparation of Ir@NC: Dissolve 15 mg of IrCl3·3H2O, 3 ml of 0.5 M PAH, and 36 mg of NC in 33 ml of deionized water and stir for 30 min, add 2 ml of 1 M NaOH and 3 ml of formaldehyde solution, stir for 30 min, transfer to a reaction kettle, and react at 200 °C for 8 h.
6. The preparation method of the electrocatalytic water splitting hydrogen production catalyst based on the hollow shell structure according to claim 1, characterized in that, The method for loading Ir nanoparticles on the surface of FeP@NPC is as follows: Preparation of Ir-FeP@NC: Dissolve IrCl3·3H2O, PAH, and FeP@NC in deionized water and stir, add NaOH and formaldehyde solution, stir and then transfer to a reaction kettle for hydrothermal reaction, wash, centrifuge, and dry the reacted suspension to obtain the finished Ir-FeP@NPC electrocatalytic water splitting hydrogen evolution catalyst.
7. The preparation method of the electrocatalytic water splitting hydrogen production catalyst based on the hollow shell structure according to claim 6, wherein: Dissolve 12 - 18 mg of IrCl3·3H2O, 3 mL of 0.5 M PAH, and 36 mg of FeP@NC in 33 mL of deionized water and stir for 30 min, add 2 mL of 1 M NaOH and 3 mL of formaldehyde solution, stir for 30 min, transfer to a reaction kettle, and react at 200 °C for 8 h. Wash, centrifuge, and dry the suspension obtained after the reaction to obtain the Ir-FeP@NC catalytic water splitting hydrogen evolution catalyst.
8. The electrocatalytic water splitting hydrogen evolution catalyst prepared by the preparation method of the electrocatalytic water splitting hydrogen evolution catalyst based on the hollow shell structure according to any one of claims 1 - 7.
9. Use of the electrocatalytic water splitting hydrogen production catalyst according to claim 8 in the electrocatalytic water splitting for hydrogen production.
10. The application according to claim 9, characterized in that The preparation method of the electrode material using the electrocatalytic water splitting hydrogen production catalyst as the raw material is as follows: Take 5 mg of Ir-FeP@NC, 1.5 mg of carbon black, 250 μL of deionized water, 250 μL of absolute ethanol, and 50 μL of a 5% Nafion 117 solution by mass fraction, and ultrasonically treat for 30 minutes to form a slurry; Take 10 μL of the slurry and drop it onto a polished and cleaned glassy carbon electrode, and make the electrode after natural drying.