A bifunctional boron-doped molybdenum-cobalt microsphere full water-splitting catalyst, a preparation method and application thereof

Abstract

The application belongs to the technical field of electrochemical bifunctional overall water splitting catalyst materials, and particularly relates to a bifunctional boron-doped molybdenum-cobalt microsphere overall water splitting catalyst as well as a preparation method and application thereof. ‑2 The application is prepared by dissolving ammonium heptamolybdate and cobalt acetate tetrahydrate in water in a small amount of sulfuric acid and sodium citrate borate system according to a certain molar ratio, heating to a transparent liquid at a constant temperature, taking foamed nickel as a working electrode, taking a platinum sheet and an Ag / AgCl electrode as a counter electrode and a reference electrode, and taking a current density of-300 to-200 mA cm ‑2 at 20-50 DEG C for 10-30 minutes, rinsing the surface of the foamed nickel with deionized water after the electrodeposition is completed, and vacuum drying to obtain a black microsphere boron-doped MoCo material loaded on the foamed nickel. The catalyst prepared by the application has the characteristics of low cost, non-toxicity, high chemical activity and stability, exhibits high hydrogen evolution and oxygen evolution activity, and low overpotential.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemical bifunctional overall water splitting catalyst materials, and particularly relates to a bifunctional boron-doped molybdenum-cobalt microsphere overall water splitting catalyst and a preparation method and application thereof. BACKGROUND

[0002] Due to the increasing consumption of traditional fossil fuels, the urgent environmental problems drive the energy demand. Electrolysis of water to produce hydrogen is an important scheme to convert renewable energy into practical chemical form due to its high energy density and no pollution. However, the electrolysis of water to produce hydrogen is limited by two half-reactions of cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER). Therefore, it is a trend to develop efficient bifunctional catalysts.

[0003] In the current catalyst materials, noble metal-based catalysts are still the mainstream materials. For example, Pt-based catalysts for HER; Ir / Ru-based catalysts for OER. Although they show ideal performance with low HER and OER overpotential, the scarcity and high cost hinder their larger-scale development. Therefore, seeking a cheap, easy-to-obtain, efficient and stable non-noble metal-based bifunctional electrocatalyst is the focus of current researchers.

[0004] Among the non-noble metal elements, molybdenum-based catalysts show excellent HER catalytic performance due to their unique structure and are a well-known catalyst for water electrolysis hydrogen evolution reaction. However, there are few reports on its OER. Cobalt-based materials are a good OER catalyst. In addition, the adjustment of the electronic structure is important to provide an optimized catalyst. Therefore, by introducing Co to effectively couple with Mo, the electronic structure is reorganized in order to prepare a bifunctional overall water splitting catalyst that can be used for both HER and OER. In addition, borides have the advantages of low cost, high structural strength and chemical stability and can prolong the service life of the catalyst. The preparation of the catalyst in a borate system can induce the formation of amorphous structure, thereby adjusting the electronic structure of the host material and producing electrocatalytic unsaturated coordination active sites. Sodium citrate can make metal ions uniformly dispersed in the electrolyte, which is beneficial to uniform deposition on the electrode surface. Therefore, the preparation of boron-doped MoCo catalyst in a borate-sodium citrate system is a promising method to realize high catalytic performance and long-term stability of the bifunctional catalyst. SUMMARY

[0005] In order to solve the above technical problems, the application provides a method for preparing a bifunctional microsphere self-supporting overall water splitting catalyst material by simple one-step electrodeposition and a preparation method thereof. The catalyst prepared by the application has the characteristics of low cost, non-toxicity, high activity and high chemical stability.

[0006] To achieve the above object, the technical scheme adopted by the present application is:

[0007] A dual-functional boron-doped MoCo microsphere full water-splitting catalyst, and a preparation method thereof, the preparation method comprising the following steps:

[0008] 1) Pretreatment of the foamed nickel: cut the foamed nickel into small pieces, and ultrasonically clean them in acetone, anhydrous ethanol and deionized water respectively to remove grease, impurities and oxide layers on the surface of the foamed nickel samples, and then vacuum dry the cleaned foamed nickel samples;

[0009] 2) Preparation of the electrodeposition solution: add (NH4)6Mo7O24·H2O and Co(CH3COO)2·4H2O into 80-120 mL of deionized water in a sodium citrate-boric acid environment, then add 1-2 mL of sulfuric acid, and then add all the medicines into an electrolytic cell, and heat the electrolytic cell to a transparent solution at 20-50 DEG C, thereby obtaining the electrodeposition solution; 24

[0010] 3) Cleaning of the foamed nickel substrate: ultrasonically clean the foamed nickel treated in step 1) with a hydrochloric acid solution, and then clean the foamed nickel samples with a large amount of anhydrous ethanol and distilled water to remove the residual hydrochloric acid on the surface of the foamed nickel, and then quickly dry the cleaned foamed nickel with a hair dryer, and then immediately immerse the foamed nickel into the electrodeposition solution in the electrolytic cell;

[0011] 4) Electrodeposition preparation of the dual-functional boron-doped MoCo microsphere full water-splitting catalyst in a three-electrode system: use the foamed nickel as a working electrode, use a platinum sheet and an Ag / AgCl electrode as a counter electrode and a reference electrode, set the current density to be -300 to -200 mAcm-2, and deposit for 10-30 minutes at 20-50 DEG C; after the electrodeposition is completed, rinse the surface of the foamed nickel sample with deionized water, and vacuum dry the foamed nickel sample to obtain the dual-functional boron-doped MoCo microsphere full water-splitting catalyst. -2

[0012] Further, in step 1) of the dual-functional boron-doped MoCo microsphere full water-splitting catalyst, the foamed nickel with a thickness of 1 mm is cut into small pieces with a size of 1 cm*1.5 cm.

[0013] Further, in steps 1) and 3) of the dual-functional boron-doped MoCo microsphere full water-splitting catalyst, the ultrasonic cleaning is performed at 20-40 DEG C for 10-20 minutes, and the cleaning power is 900-1200 W.

[0014] Further, in step 1) of the dual-functional boron-doped MoCo microsphere full water-splitting catalyst, the vacuum drying is performed at 30-60 DEG C for 10-15 hours.

[0015] ​​Further, in the step 2) of the above-mentioned bifunctional boron-doped MoCo microsphere overall water-splitting catalyst, the amount of substance of ammonium heptamolybdate ((NH4)6Mo7O 24 ) accounts for 16%-27% of the total amount of substance of ammonium heptamolybdate ((NH4)6Mo7O 24 ), cobalt acetate tetrahydrate (Co(CH3COO)2·4H2O) and boric acid (H3BO3).

[0016] Further, in the step 2) of the above-mentioned bifunctional boron-doped MoCo microsphere overall water-splitting catalyst, the amount of substance of ammonium heptamolybdate ((NH4)6Mo7O 24 ) accounts for 16%-27% of the total amount of substance of ammonium heptamolybdate ((NH4)6Mo7O 24 ), cobalt acetate tetrahydrate (Co(CH3COO)2·4H2O) and boric acid (H3BO3).

[0017] Further, in the step 2) of the above-mentioned bifunctional boron-doped MoCo microsphere overall water-splitting catalyst, the amount of substance of ammonium heptamolybdate ((NH4)6Mo7O 24 ) accounts for 16%-27% of the total amount of substance of ammonium heptamolybdate ((NH4)6Mo7O 24 ), cobalt acetate tetrahydrate (Co(CH3COO)2·4H2O) and boric acid (H3BO3).

[0018] Further, in the step 2) of the above-mentioned bifunctional boron-doped MoCo microsphere overall water-splitting catalyst, the constant temperature heating condition is that the temperature is 20-50℃.

[0019] Further, in the step 3) of the above-mentioned bifunctional boron-doped MoCo microsphere overall water-splitting catalyst, the concentration of the hydrochloric acid solution is 5-8mol / L. -1 .

[0020] Further, in the step 4) of the above-mentioned bifunctional boron-doped MoCo microsphere overall water-splitting catalyst, the vacuum drying is carried out at 20-50℃ for 60-120 minutes.

[0021] The beneficial effects of the present application are:

[0022] 1、The present application can controllably prepare a self-supporting bifunctional boron-doped MoCo microsphere overall water-splitting catalyst through a one-step simple electrodeposition method, can save the cumbersome steps of coating the catalyst suspension on a glassy carbon electrode or carbon cloth, significantly improves the conductivity, and can directly test the performance, which is simple, convenient and time-saving.

[0023] 2、The application can control different morphologies by changing different electrodeposition current, electrodeposition time, sulfuric acid concentration, boric acid concentration and electrolyte substance and ratio, etc., and can prepare micron-sized spherical materials by a simple one-step electrodeposition method, and the formed catalyst plating layer presents a relatively uniform spherical shape, and the surface of the spherical catalyst is observed to be uneven and lotus seed skin-like after amplification, and this structure can provide a larger specific surface area, thereby providing more active sites, and finally improving the catalytic activity.

[0024] 3、The bifunctional boron-doped MoCo micron sphere full water splitting catalyst prepared by the one-step simple electrodeposition method has a simple process flow, is easy to operate, can reduce waste liquid pollution to a certain extent, is economic and environmentally friendly, is prepared in a boric acid sodium citrate system, and high-catalytic-activity catalyst is obtained, raw materials are cheap and easy to obtain, and commercial production is more favorable. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Figure 1 is a SEM diagram of a self-supporting bifunctional boron-doped MoCo micron sphere full water splitting catalyst prepared in embodiment 1 of the application, and the magnification is 0.5K, 5K, 20K and 100K respectively.

[0026] Figure 2 Figure 2 is an XRD diagram of the self-supporting bifunctional boron-doped MoCo micron sphere full water splitting catalyst prepared in embodiment 1 of the application.

[0027] Figure 3 Figure 3 is an ICP diagram of the self-supporting bifunctional boron-doped MoCo micron sphere full water splitting catalyst prepared in embodiment 1 of the application.

[0028] Figure 4 Figure 4 is a TEM diagram of the self-supporting bifunctional boron-doped MoCo micron sphere full water splitting catalyst prepared in embodiment 1 of the application.

[0029] Figure 5 Figure 5 is a diagram of the change of oxygen and hydrogen amounts with time when the self-supporting bifunctional boron-doped MoCo micron sphere full water splitting catalyst prepared in embodiment 1 of the application is collected at a current density of 600 mA cm -2 .

[0030] Figure 6 Figure 6 is an LSV curve of the self-supporting bifunctional boron-doped MoCo micron sphere full water splitting catalyst deposited at different current densities, wherein figure (a) is an electrochemical HER performance polarization curve, and figure (b) is an electrochemical OER performance polarization curve.

[0031] Figure 7 Figure 7 is an LSV curve of the self-supporting bifunctional boron-doped MoCo micron sphere full water splitting catalyst deposited at different times, wherein figure (a) is an electrochemical HER performance polarization curve, and figure (b) is an electrochemical OER performance polarization curve.

[0032] Figure 8 Figure 1 shows the LSV curves obtained by depositing self-supporting bifunctional boron-doped MoCo microsphere water-splitting catalysts at different sulfuric acid concentrations. Figure 2(a) shows the polarization curve of electrochemical HER performance, and Figure 3(b) shows the polarization curve of electrochemical OER performance.

[0033] Figure 9 Figure 1 shows the LSV curves obtained by depositing self-supporting bifunctional boron-doped MoCo microsphere water-splitting catalysts at different boric acid concentrations. Figure 2(a) shows the polarization curve of electrochemical HER performance, and Figure 3(b) shows the polarization curve of electrochemical OER performance.

[0034] Figure 10 To obtain LSV curves by depositing different materials, Figure (a) shows the polarization curve of electrochemical HER performance, and Figure (b) shows the polarization curve of electrochemical OER performance.

[0035] Figure 11 Figure 1 shows the LSV curves obtained under different molybdenum-cobalt ratios. Figure 2(a) shows the polarization curve of the electrochemical HER performance, and Figure 3(b) shows the polarization curve of the electrochemical OER performance.

[0036] Figure 12 Figure 1 shows the LSV curves of the self-supporting bifunctional boron-doped MoCo microsphere water-splitting catalyst prepared in Example 1 of this invention. Figure (a) is the iR-corrected HER performance polarization curve, and Figure (b) is the iR-corrected OER performance polarization curve.

[0037] Figure 13 This is the LSV curve of the complete water splitting of the self-supporting bifunctional boron-doped MoCo microsphere catalyst prepared in Example 1 of this invention.

[0038] Figure 14 This is an it curve of the total water splitting of the self-supporting bifunctional boron-doped MoCo microsphere catalyst prepared in Example 1 of this invention. Detailed Implementation

[0039] Example 1

[0040] (I) Preparation method

[0041] 1) Pretreatment of nickel foam: Cut 1mm thick nickel foam (NF) into 1cm×1.5cm pieces and ultrasonically clean them for 15 minutes (1000W) in acetone, anhydrous ethanol and deionized water at room temperature to remove grease, impurities and oxide layer from the surface of the nickel foam samples. Place the cleaned nickel foam samples in a vacuum drying oven and dry them at 50℃ for 12h.

[0042] 2) Preparation of electrodeposition solution: Ammonium heptamolybdate ((NH4)6Mo7O 24)0.1875M, cobalt acetate tetrahydrate (Co(CH3COO)2.4H2O) 0.0625M, ammonium heptamolybdate ((NH4)6Mo7O 24 ) and cobalt acetate tetrahydrate (Co(CH3COO)2.4H2O) 0.25M, boric acid (H3BO3) 0.5M and sodium citrate (C6O7H5Na3.2H2O) 0.3M were weighed, and then sulfuric acid (H2SO4) 0.5M was added. All the chemicals were added to 100 mL of deionized water, and the solution was heated to a transparent solution at 30°C and 15 r / min, which was the electrodeposition solution.

[0043] 3) Cleaning the foam nickel substrate: the foam nickel treated in step 1) was cleaned with 6 mol / L hydrochloric acid solution at room temperature for 15 minutes (power 1000 W), and then the foam nickel sample was cleaned several times with anhydrous ethanol and distilled water in an ultrasonic machine to remove the residual hydrochloric acid on the surface. The cleaned foam nickel was quickly dried with a hair dryer and then immediately immersed in the electrodeposition solution in the electrolytic cell. -1

[0044] 4) Electrodeposition of self-supported dual-functional boron-doped MoCo microspheres for overall water splitting in a three-electrode system: foam nickel was used as the working electrode, platinum and Ag / AgCl electrodes were used as the counter electrode and reference electrode, and the current density was set to -250 mA / cm2. The electrodeposition was carried out at 30°C for 120 minutes. -2

[0045] 5) After the electrodeposition was completed, the foam nickel sample was rinsed with deionized water and dried in a vacuum drying oven at 30°C for 120 minutes to obtain the self-supported dual-functional boron-doped MoCo microspheres for overall water splitting catalyst.

[0046] Figure 1 The SEM images of the self-supported dual-functional boron-doped MoCo microspheres for overall water splitting catalyst are shown in Figures 1-4, with magnifications of 0.5K, 5K, 20K and 100K. As can be seen from the images, the coating layer presents a relatively uniform spherical shape, and the surface is relatively rough. Upon magnification, it can be seen that the shape is similar to that of a durian skin. This structure can expose more active sites and increase the specific surface area.

[0047] Figure 2 The XRD pattern of the self-supported dual-functional boron-doped MoCo microspheres for overall water splitting catalyst is shown in Figure 5. The XRD spectrum is consistent with Co (PDF # 15-0806). The sample has three diffraction peaks and one package peak, which are the (111), (200) and (220) crystal planes of Co and the amorphous package peak of B, indicating that cobalt and boron are successfully loaded on the foam nickel by electrodeposition.

[0048] Figure 3 ​​ICP spectrum of self-supported bifunctional boron-doped MoCo microspheres full water splitting catalyst. From the ICP spectrum, it can be seen that the catalyst of Example 1 contains 42.423% Mo element, 43.272% Co element and 13.327% B element, indicating that molybdenum, cobalt and boron are successfully loaded on the nickel foam by electrodeposition.

[0049] Figure 4 TEM image of self-supported bifunctional boron-doped MoCo microspheres full water splitting catalyst. The low magnification TEM morphology and high resolution HRTEM image of the deposited coating are shown respectively. From the figure, the morphology of amorphous Mo, B and Co with clear lattice fringes can be seen. From the mapping diagram, the existence of Mo and Co elements can be further proved, but the existence of B element is not found, which is considered to be because boron is an element with very low atomic number, and its scattering ability is very small, so it is difficult to be detected by electron beam scattering.

[0050] Figure 5 The amount of oxygen and hydrogen collected at a current density of 600 mA cm -2 -2 after 1299 s of electrolysis of water, 25 mL of oxygen and 50 mL of hydrogen were collected, and the calculated Faraday efficiency was 99.6%, with good conversion efficiency.

[0051] (B) Electro-catalytic performance detection

[0052] The electro-catalytic performance of the catalyst was detected: in a three-electrode system at room temperature and pressure, the electrolyte was 1M KOH aqueous solution, the self-supported bifunctional boron-doped MoCo microspheres full water splitting catalyst was the working electrode, the platinum plate was the counter electrode, and the Ag / AgCl electrode was the reference electrode.

[0053] Figure 6 LSV curve of self-supported bifunctional boron-doped MoCo microspheres full water splitting catalyst deposited at different current densities, in order to obtain the best current density during deposition. According to the curve, the HER performance is best at a current density of -300 mA cm -2 -2, the HER overpotential is 122.89 mV, and the OER performance is best at a current density of -250 mA cm -2 -2, the OER overpotential is 349.1 mV. Considering the performance at a current density of -250 mA cm -2 -2 is the best, the HER overpotential is 149.9 mV, and the OER overpotential is 349.1 mV. Therefore, the electrodeposition time is studied at a current density of -250 mA cm -2 -2. It is divided into 300 s, 600 s, 900 s, 1200 s and 1500 s.

[0054] Figure 7 LSV curves of self-supporting bifunctional boron-doped MoCo microspheres full water-splitting catalyst deposited at different times were obtained to determine the optimal deposition time. According to the curve, the performance is best when the electrodeposition time is 1200 s, the HER overpotential is 97.9 mV, and the OER overpotential is 337.1 mV. Therefore, based on the current density of -250 mA cm -2 -2, the deposition time of 1200 s, and the sulfuric acid concentration of 0.25 M, the boronic acid concentration is continued to be used as a variable for further study. 0.25 M, 0.5 M, and 1 M were added, respectively.

[0055] Figure 8 LSV curves of self-supporting bifunctional boron-doped MoCo microspheres full water-splitting catalyst deposited at different sulfuric acid concentrations were obtained to determine the optimal sulfuric acid concentration. According to the curve, the performance is best when the sulfuric acid concentration is 0.25 M, the HER overpotential is 85.9 mV, and the OER overpotential is 340.1 mV. Therefore, based on the current density of -250 mA cm -2 -2, the deposition time of 1200 s, and the sulfuric acid concentration of 0.25 M, the boronic acid concentration is continued to be used as a variable for further study. 0.25 M, 0.5 M, and 1 M were added, respectively.

[0056] Figure 9 LSV curves of self-supporting bifunctional boron-doped MoCo microspheres full water-splitting catalyst deposited at different boronic acid concentrations were obtained to determine the optimal boronic acid concentration. According to the curve, the performance is best when the boronic acid concentration is 0.5 M, the HER overpotential is 85.9 mV, and the OER overpotential is 340.1 mV. Therefore, based on the current density of -250 mA cm -2 -2, the deposition time of 1200 s, the sulfuric acid concentration of 0.25 M, and the boronic acid concentration of 0.5 M, the substance during deposition is continued to be used as a variable for further study. FeCoB, FeMoB, MoCoB, FeCoBSe, and FeMoBSe were used, respectively.

[0057] Figure 10 LSV curves of self-supporting bifunctional boron-doped MoCo microspheres full water-splitting catalyst deposited at different boronic acid concentrations were obtained to determine the optimal boronic acid concentration. According to the curve, the performance is best when the boronic acid concentration is 0.5 M, the HER overpotential is 85.9 mV, and the OER overpotential is 340.1 mV. Therefore, based on the current density of -250 mA cm

[0058] Figure 11The LSV curves obtained for different molybdenum cobalt ratios are used to obtain the optimal ratio suitable for boron-doped MoCo catalysts. According to the graph, the performance is best when molybdenum: cobalt = 3:1, the HER overpotential is 67.9 mV, and the OER overpotential is 340.1 mV. Therefore, boron-doped molybdenum cobalt is the best species.

[0059] Figure 12 The LSV curves of the self-supported bifunctional boron-doped MoCo microsphere catalyst for full water splitting are used to characterize the catalytic activity of the sample, and the test conditions are a three-electrode system, an Ag / AgCl electrode as a reference electrode, a platinum sheet as a counter electrode, a sample as a working electrode, and an electrolyte as a 1M KOH aqueous solution. As can be seen from the image, after 80% overpotential compensation, the overpotential is 49.53 mV at a current density of -10 mA cm -2 , and the overpotential is 321.60 mV at a current density of 10 mA cm -2 . The lower the overpotential of water electrolysis, the higher the total voltage required for water electrolysis and the conversion efficiency of electrical energy into hydrogen energy, and the higher the Faraday efficiency. Therefore, it has good commercial prospects.

[0060] Figure 13 The LSV curve of the self-supported bifunctional boron-doped MoCo microsphere catalyst for full water splitting prepared in Example 1 of the present application is shown in the figure. As can be seen from the image, the full cell voltage for full water splitting is 1.617 V at a current density of 10 mA cm -2 , which is close to most of the existing electrode materials.

[0061] Figure 14 The i-t curve of the self-supported bifunctional boron-doped MoCo microsphere catalyst for full water splitting prepared in Example 1 of the present application is shown in the figure. As can be seen from the image, the full cell voltage for full water splitting is stably maintained at about 1.7 V for 50 h at a current density of 10 mA cm -2 , indicating that the material has good stability.

[0062] The above has made an exemplary description of the present application, and it should be noted that any simple modification, modification or equivalent replacement that does not deviate from the core of the present application and can be easily replaced by those skilled in the art without creative labor falls within the protection scope of the present application.

Claims

1. A bifunctional boron-doped molybdenum-cobalt microsphere water-splitting catalyst, characterized in that, The preparation method includes the following steps: 1) Pretreatment of nickel foam: Cut the nickel foam into small pieces and ultrasonically clean them in acetone, anhydrous ethanol and deionized water respectively to remove grease, impurities and oxide layer from the surface of the nickel foam sample. Vacuum dry the cleaned nickel foam sample. 2) Preparation of electrodeposition solution: Ammonium heptamolybdate (NH4)6Mo7O 24 Cobalt acetate tetrahydrate Co(CH3COO)2·4H2O is dissolved in deionized water in a borate-citrate system, and then sulfuric acid is added. The solution is heated at a constant temperature until it becomes a transparent solution, which is the electrodeposition solution. 3) Cleaning the substrate nickel foam: The nickel foam treated in step 1) is ultrasonically cleaned with hydrochloric acid solution, then rinsed repeatedly with a large amount of anhydrous ethanol and distilled water to remove the residual hydrochloric acid on its surface, quickly air-dried, and then immediately immersed in the electrodeposition solution. 4) Preparation of bifunctional boron-doped MoCo microsphere water-splitting catalyst by electrodeposition in a three-electrode system: Nickel foam was used as the working electrode, and platinum sheets and Ag / AgCl electrodes were used as the counter and reference electrodes, respectively. The electrodeposition conditions were as follows: the current density was set to -300 to -200 mA·cm⁻¹. -2 The sample was deposited at 20-50℃ for 10-30 minutes, rinsed with deionized water, and vacuum dried to obtain a bifunctional boron-doped MoCo microsphere water-splitting catalyst.

2. The bifunctional boron-doped molybdenum-cobalt microsphere water-splitting catalyst according to claim 1, characterized in that, In step 1), the 1mm thick nickel foam is cut into 1cm × 1.5cm pieces.

3. The bifunctional boron-doped molybdenum-cobalt microsphere water-splitting catalyst according to claim 1, characterized in that, In steps 1) and 3), the ultrasonic cleaning is performed at 20-40°C for 10-20 minutes with a cleaning power of 900-1200 W.

4. The bifunctional boron-doped molybdenum-cobalt microsphere water-splitting catalyst according to claim 1, characterized in that, In step 1), the vacuum drying is performed at 30-60℃ for 10-15 hours.

5. The bifunctional boron-doped molybdenum-cobalt microsphere water-splitting catalyst according to claim 1, characterized in that, In step 2), ammonium heptamolybdate (NH4)6Mo7O 24 The molar percentage of ammonium heptamolybdate (NH4)6Mo7O 24 The total amount of cobalt acetate tetrahydrate Co(CH3COO)2·4H2O and boric acid H3BO3 is 16%-27%.

6. The bifunctional boron-doped molybdenum-cobalt microsphere water-splitting catalyst according to claim 5, characterized in that, In step 2), the amount of cobalt acetate tetrahydrate Co(CH3COO)2·4H2O accounts for a certain percentage of the amount of ammonium heptamolybdate (NH4)6Mo7O. 24 The total amount of cobalt acetate tetrahydrate Co(CH3COO)2·4H2O and boric acid H3BO3 is 5%-17%.

7. The bifunctional boron-doped molybdenum-cobalt microsphere water-splitting catalyst according to claim 5, characterized in that, In step 2), the amount of boric acid H3BO3 accounts for a certain percentage of the amount of ammonium heptamolybdate (NH4)6Mo7O. 24 The total amount of cobalt acetate tetrahydrate Co(CH3COO)2·4H2O and boric acid H3BO3 is 60%-70%.

8. The bifunctional boron-doped molybdenum-cobalt microsphere water-splitting catalyst according to claim 1, characterized in that, In step 2), the temperature of the constant temperature heating is 20-50℃.

9. The application of the bifunctional boron-doped molybdenum-cobalt microsphere water-splitting catalyst according to any one of claims 1-8 in water electrolysis.

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