CuO@MnNi electrocatalyst, preparation method thereof and application of CuO@MnNi electrocatalyst in glucose oxidation and hybrid zinc-air battery
By using CuO@MnNi electrocatalyst to replace the oxygen evolution reaction in a zinc-air battery, the problem of low efficiency in traditional zinc-air batteries was solved, achieving efficient glucose oxidation and improved battery performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NORTHEAST AGRICULTURAL UNIVERSITY
- Filing Date
- 2025-05-26
- Publication Date
- 2026-05-15
AI Technical Summary
Traditional zinc-air batteries have a high activation energy barrier for the oxygen evolution reaction and slow reaction kinetics, resulting in low battery efficiency.
Using CuO@MnNi electrocatalyst as the positive electrode material, a zinc-air battery was assembled by forming a CuO array on the surface of copper foam and growing a nanoscale flower-like MnNi structure by solvothermal method, replacing the traditional oxygen evolution reaction, and using an electrolyte containing glucose.
The charging potential was reduced, the battery's round-trip efficiency and stability were improved, the electrode fabrication process was simplified, the cost was reduced, and the battery was stably cycled for 1100 hours at a current density of 2 mA/cm2.
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Figure CN120565694B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a CuO@MnNi electrocatalyst, its preparation method, and its application in glucose oxidation and hybrid zinc-air batteries, belonging to the field of catalyst and its preparation technology. Background Technology
[0002] The oxygen evolution reaction (OER) has a high activation energy barrier, and its complex and slow kinetics severely hinder the efficiency of zinc-air batteries. From a thermodynamic perspective, many organic oxidation reactions have lower theoretical potentials; for example, the theoretical potential of the hydrazine oxidation reaction (HzOR) is only -0.33V, far lower than the theoretical potential of the OER (1.23V). However, from a kinetic perspective, some organic oxidation reactions are much faster, such as the urea oxidation reaction (UOR) and the methanol oxidation reaction (MOR). These reactions have faster reaction rates and can proceed at lower overpotentials. Furthermore, organic oxidation reactions typically involve multiple proton-coupled electron transfer steps, and high-value-added products can be obtained by controlling the reaction pathway. For example, methanol oxidation can produce high-value-added chemicals such as formate. All these theoretical considerations demonstrate that using organic oxidation to replace the slow OER process is a feasible strategy. Therefore, providing a hybrid zinc-air battery and its cathode material is essential. Summary of the Invention
[0003] To address the problem of high activation energy barrier and slow reaction kinetics leading to low battery efficiency in conventional zinc-air batteries, this invention provides a CuO@MnNi electrocatalyst, its preparation method, and its application in glucose oxidation and hybrid zinc-air batteries.
[0004] The technical solution of this invention:
[0005] One objective of this invention is to provide a method for preparing a positive electrode material for a hybrid zinc-air battery, the method comprising the following steps:
[0006] (1) Using a mixed aqueous solution of sodium hydroxide and ammonium persulfate as a pre-modification solution, copper foam was immersed in the pre-modification solution to obtain pre-modified copper foam, and after heat treatment, CuO array substrate was obtained.
[0007] (2) Using CuO array substrate as raw material, methanol as solvent, PVP as surfactant, and manganese nitrate and nickel nitrate as metal source, CuO@MnNi catalyst was prepared by solvothermal method, which is the positive electrode material of hybrid zinc-air battery.
[0008] Further specified, the concentration of sodium hydroxide in the pre-modified solution of (1) is 1.5 to 2.5 mol / L, and the concentration of ammonium persulfate is 0.10 to 0.15 mol / L.
[0009] Further specified, (1) the immersion temperature is room temperature and the time is 3 to 12 minutes.
[0010] Further specifying, in (1), the volume ratio of copper foam to pre-modified liquid is 6 cm⁻¹. 2 250mL.
[0011] Further specified, (1) the heat treatment temperature is 200℃ and the time is 0.5~1.5h.
[0012] Further, the reaction temperature of the solvothermal method in (2) is 160-180℃ and the time is 4-10h.
[0013] The second objective of this invention is to provide a CuO@MnNi catalyst prepared by the above method, wherein the catalyst comprises a CuO array and a manganese-nickel bimetallic flower-like structure material coated on the surface of the CuO array.
[0014] The third objective of this invention is to provide an application of the above-mentioned CuO@MnNi catalyst, specifically for catalyzing the oxidation of glucose.
[0015] The fourth objective of this invention is to provide an application of the above-mentioned CuO@MnNi catalyst, specifically its direct use as the positive electrode in a hybrid zinc-air battery.
[0016] The fifth objective of this invention is to provide a hybrid zinc-air battery, which uses the above-mentioned CuO@MnNi catalyst as the positive electrode, a zinc sheet as the negative electrode, and a KOH solution containing glucose as the electrolyte.
[0017] Further specified, the glucose content in the electrolyte is 0.4–0.8 mol / L.
[0018] Beneficial effects:
[0019] (1) This invention uses copper foam as a substrate material to form a CuO array on its surface, and then grows nanoscale flower-like MnNi on the CuO array using a solvothermal method to obtain a CuO@MnNi oxygen reduction self-supporting electrocatalyst. This catalyst has excellent glucose oxidation activity, with an overpotential of only 154 mV. This catalyst can also be used directly as a positive electrode material for zinc-air batteries. Using zinc sheets as the negative electrode and a 6M KOH solution containing 0.6 mol / L glucose as the electrolyte, a hybrid zinc-air battery is assembled. During charging, the glucose oxidation reaction catalyzed by CuO@MnNi replaces the traditional oxygen evolution reaction (OER) process, reducing the charging potential from 1.80 V to 1.57–1.73 V. Moreover, the array-like CuO can better disperse the catalyst, increase the contact between the catalyst and the electrolyte, thereby providing abundant active sites, improving the round-trip efficiency and stability of the metal-air battery, and enabling the battery round-trip efficiency to reach a maximum of 78% at 2 mA / cm². 2 It can be stably cycled for 1100 hours under constant current charge and discharge at a current density.
[0020] (2) The CuO@MnNi oxygen reduction self-supporting electrocatalyst prepared by the present invention has an array-shaped substrate that can also be used to bond and disperse the catalyst to obtain highly loaded active components, thereby providing abundant active sites.
[0021] (3) This invention uses a nano-hierarchical structure grown directly on a conductive substrate as a self-supporting catalyst. Compared with traditional powder catalysts, this avoids the need for post-coating processes and the addition of binders and conductive agents, simplifies the electrode preparation process, reduces costs, and improves process stability. Attached Figure Description
[0022] Figure 1 Scanning electron microscope (SEM) images (at different magnifications) of the CuO@MnNi self-supporting electrocatalyst prepared in Example 1;
[0023] Figure 2 Linear sweep voltammetry curves of the CuO@MnNi self-supporting electrocatalyst prepared in Example 1;
[0024] Figure 3 A comparison diagram of constant current charge and discharge of the zinc-air battery assembled in Example 1;
[0025] Figure 4 Charge-discharge curves of a zinc-air battery assembled with the CuO@MnNi self-supporting electrocatalyst prepared in Example 1 for different cycles;
[0026] Figure 5 The chart shows a comparison of the round-trip efficiency of the zinc-air battery assembled in Example 1. Detailed Implementation
[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.
[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art may make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.
[0029] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.
[0030] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.
[0031] Implementation Method 1:
[0032] The process for preparing the positive electrode material of the hybrid zinc-air battery according to the present invention is as follows:
[0033] Step 1: Form a CuO array on the surface of the copper foam to obtain an array-shaped CuO substrate:
[0034] A mixed aqueous solution of sodium hydroxide and ammonium persulfate was used as a pre-modification solution to pre-modify copper foam to grow a layer of Cu(OH)2 on the surface of the copper foam, thus obtaining pre-modified copper foam. The pre-modified copper foam was then heat-treated at 200℃ to pyrolyze the Cu(OH)2 on the surface of the copper foam into a CuO array during the heat treatment process, thus obtaining a CuO array substrate.
[0035] To ensure the formation of a CuO array on the surface of copper foam, this invention first uses a mixed aqueous solution of sodium hydroxide and ammonium persulfate as a pre-modification solution. Ammonium persulfate has strong oxidizing properties, capable of oxidizing the copper foam and growing a Cu(OH)₂ array in situ on the surface of the copper foam substrate. Subsequent heat treatment allows the Cu(OH)₂ to pyrolyze into CuO at high temperatures, thereby forming a CuO array on the copper foam surface. Sodium hydroxide provides an alkaline environment to promote the decomposition of ammonium persulfate and simultaneously provides OH⁻ for the formation of the Cu(OH)₂ array. - This promotes the oxidation reaction of Cu.
[0036] This invention takes into account that while higher concentrations of sodium hydroxide and ammonium persulfate in the pre-modified solution can increase the oxidation rate of the Cu substrate, the size of the extracted Cu(OH)₂ nanowire array is difficult to control, and too low a concentration may result in incomplete reaction and failure to form the Cu(OH)₂ array. Therefore, this invention comprehensively considers both the reaction objective and the stability of the reaction system, and the concentration of sodium hydroxide in the pre-modified solution used in this invention is 1.5–2.5 mol / L; the concentration of ammonium persulfate is 0.10–0.15 mol / L.
[0037] To further ensure the impregnation effect and achieve a uniform formation of Cu(OH)₂ nanowire arrays on the surface of the pre-modified copper foam, which facilitates its transformation into a uniform CuO array during subsequent heat treatment, this invention involves impregnating the cleaned copper foam in a pre-modification solution. The impregnation temperature is room temperature, and the impregnation time is 3–12 minutes. The ratio of copper foam to pre-modification solution is 6 cm⁻¹. 2 250mL.
[0038] Since the surface of copper foam mainly exists in the form of Cu(OH)2 after being impregnated in a mixed aqueous solution of sodium hydroxide and ammonium persulfate, in order to convert Cu(OH)2 into CuO, this invention uses heat treatment to convert Cu(OH)2 on the surface of copper foam into CuO at high temperature, thereby obtaining a CuO array substrate.
[0039] This invention utilizes a combination of sodium hydroxide and ammonium persulfate impregnation and heat treatment to generate CuO nanowire arrays on the surface of copper foam. These arrays are not only structurally stable but also provide more nucleation sites. Compared to traditional pure substrates such as copper foam and nickel foam, the presence of CuO nanowires in the CuO array substrate prepared by this invention facilitates further exposure of the nucleation sites, allowing for better contact between the catalyst and the electrolyte, thereby improving subsequent catalytic activity.
[0040] In this invention, the specific heat treatment process is not limited, as long as it can convert Cu(OH)2 on the surface of the copper foam into CuO at high temperature. For example, CuO array substrates can be obtained by heat treatment at 200°C for 1–1.5 hours in a tube furnace under a nitrogen atmosphere. Alternatively, CuO array substrates can be obtained by heat treatment in an air atmosphere in a muffle furnace for 1–1.5 hours.
[0041] This invention takes into account that the presence of oxides and other impurities on the surface of the original copper foam may lead to uneven growth of Cu(OH)₂, resulting in uneven CuO formation and solvothermal reactions. Therefore, the copper foam needs to be cleaned before use to remove any potential impurities. To quickly and efficiently remove impurities such as oxides from the copper foam, in a preferred embodiment of this invention, ultrasonic cleaning is used with ethanol as the cleaning agent. The ultrasonic frequency is 60–80 kHz, and the ultrasonic time is 30 minutes, so that the oxides and other impurities on the surface of the copper foam are removed through the synergistic effect of ethanol and ultrasound. It is important to note that the water temperature will rise during the ultrasonic process; if the water temperature is too high, it will cause oxidation of the copper foam surface, so the water should be changed regularly.
[0042] After the ultrasonic treatment is completed, the ethanol on the surface of the foamed copper is washed off with deionized water and then dried. This invention does not limit the specific drying process parameters. For example, in a preferred embodiment of this invention, the temperature for drying the cleaned foamed copper is 50–60°C, and the drying time is 4–8 hours.
[0043] Step 2: After solvothermal reaction treatment on the surface of CuO array substrate, CuO@MnNi electrocatalyst is obtained;
[0044] This invention regulates the solvothermal reaction time to improve the bonding effect between MnNi and the CuO array on the substrate surface. Both excessively sparse and excessively dense MnNi growth negatively impact performance; excessive sparse growth reduces catalyst performance, while excessive density covers the CuO array structure, negating its advantages. To ensure the desired effect, the preferred solvothermal reaction time in this invention is 6 hours.
[0045] It should be emphasized that, in order to ensure the uniform formation of a manganese-nickel bimetallic flower-like nanostructure on the surface of the modified copper foam, in a preferred embodiment of the present invention, the preparation method for uniformly forming a layer of MnNi on the surface of the modified copper foam is as follows: The modified copper foam is first immersed in a mixed solution of metal ions and PVP (a methanol solution of manganese ions and nickel ions) at room temperature for 5 min. Then, it is transferred to a reaction vessel and reacted at 180°C for 6 h, wherein the molar ratio of nickel salt to manganese salt is 4-8:1.
[0046] Example 1:
[0047] This embodiment provides a CuO@MnNi oxygen reduction self-supporting electrocatalyst, and its preparation method includes the following steps:
[0048] Step 1: Form a CuO array on the surface of the copper foam:
[0049] 1) Cut 1.0mm thick copper foam into 2cm×3cm sizes, then immerse it completely in ethanol and sonicate it at an ultrasonic frequency of 70kHz for 30 minutes to remove surface oxides. Wash off the ethanol on the surface with deionized water to obtain clean copper foam.
[0050] 2) Disperse sodium hydroxide and ammonium persulfate sequentially in deionized water to prepare a pre-modified solution with a sodium hydroxide molar concentration of 2.0 mol / L and an ammonium persulfate molar concentration of 0.15 mol / L.
[0051] 3) Completely immerse the cleaned copper foam in 250 mL of the pre-modified solution prepared above, and soak at room temperature for 12 min, then remove it. Wash the soaked copper foam three times with deionized water to remove the residual pre-modified solution on the surface, and then dry it in an oven at 60°C for 6 h to remove excess deionized water, thus obtaining the pre-modified copper foam.
[0052] 4) The pre-modified copper foam obtained above is placed in a tube furnace and heated to 200°C at a heating rate of 2°C / min under a nitrogen atmosphere, and then held at 200°C for 1 hour to obtain a CuO array substrate.
[0053] Step 2: Solvent-thermally grow flower-like MnNi nanostructures on the surface of the above CuO array substrate.
[0054] 1) Place 1.0178g of nickel nitrate and 0.1044g of manganese nitrate in 35mL of methanol to prepare a mixed solution.
[0055] 2) Add 0.6g of polyvinylpyrrolidone to the mixed solution and stir magnetically for 30min.
[0056] 3) The CuO array substrate obtained in step 1 was immersed in the prepared mixed solution for 5 min at room temperature. Then, the CuO and solution were transferred together to a reactor and reacted at 180°C for 6 h. After filtration, washing and drying, CuO@MnNi oxygen reduction self-supported electrocatalyst was obtained.
[0057] The microstructure of the obtained CuO@MnNi oxygen reduction self-supporting electrocatalyst was characterized by scanning electron microscopy (SEM). The results are shown below. Figure 1 As shown. By Figure 1The test results show that CuO nanowires are densely and uniformly distributed on the surface of the copper foam substrate in the CuO@MnNi self-supporting electrocatalyst. Manganese nitrate and nickel nitrate react under solvothermal conditions to form a flower-like substance that uniformly coats each CuO nanowire, maximizing the advantages of the CuO array and allowing the catalyst supported on CuO to fully contact the electrolyte for better mass transfer.
[0058] The electro-oxidation-reduction performance of the obtained CuO@MnNi oxygen reduction self-supporting electrocatalyst was further characterized. Specifically, linear sweep voltammetry tests were performed in different electrolytes, and the test results are as follows: Figure 2 As shown. Glucose oxidation represents an electrolyte containing glucose (6M KOH solution containing 0.6 mol / L glucose as the electrolyte), and ORE represents a conventional electrolyte (6M KOH solution as the electrolyte). From Figure 2 The test results show that the CuO@MnNi self-supporting electrocatalyst exhibits a significant performance improvement in the presence of glucose in the electrolyte during electrochemical applications. This demonstrates that glucose oxidation replaces the oxidation reaction (OER). The overpotential of OER is 369 mV, while the overpotential of glucose oxidation is only 154 mV. This indicates that the prepared catalytic electrode has excellent reaction efficiency and superior performance for glucose oxidation.
[0059] Furthermore, a hybrid zinc-air battery was assembled using the prepared CuO@MnNi oxygen reduction self-supported electrocatalyst as the positive electrode, a zinc sheet as the negative electrode, and a 6M KOH solution containing 0.6 mol / L glucose as the electrolyte. To better illustrate that glucose oxidation replaced OER in the CuO@MnNi oxygen reduction self-supported electrocatalyst, a conventional zinc-air battery was assembled using the prepared CuO@MnNi oxygen reduction self-supported electrocatalyst as the positive electrode, a zinc sheet as the negative electrode, and a 6M KOH solution as the electrolyte. The performance of the prepared hybrid zinc-air battery and the conventional zinc-air battery were compared. Specific constant current charge-discharge test results are as follows: Figures 3-5 As shown. By Figure 3 The test results show that the CuO@MnNi self-supporting electrocatalyst remains stable after 700 hours of charge-discharge operation in the practical application of zinc-air batteries, regardless of whether the electrolyte contains glucose. However, the charging voltage of traditional zinc-air batteries is basically maintained at 1.78–1.80V, while the charging voltage of the hybrid battery for glucose oxidation is 1.57–1.73V. Figure 3 The test results show that the battery operates stably under different cycle counts. Plotting the integer number of cycles separately yields... Figure 4 By calculating the round-trip efficiency, such as Figure 5As shown, the round-trip efficiency remains stable at nearly 70% after 1500 cycles. In summary, thanks to the glucose oxidation reaction replacing the OER process, the charging voltage is reduced, avoiding the oxidation of the positive electrode catalyst caused by excessively high charging potential during long-term charge-discharge processes, which would exacerbate the deactivation of active sites and the shedding of active species, thus reducing battery performance.
[0060] Example 2:
[0061] The difference between this embodiment and embodiment 1 is that the solvothermal reaction temperature in step 2, 3) is 180°C and the time is 4 hours. The remaining process steps and parameter settings are the same as in embodiment 1.
[0062] Example 3:
[0063] The difference between this embodiment and embodiment 1 is that the solvothermal reaction temperature in step 2, 3) is 180°C and the time is 8 hours. The remaining process steps and parameter settings are the same as in embodiment 1.
[0064] Comparative Example 1:
[0065] The difference between this comparative example and Example 1 is that in step 2, 1), the amount of nickel nitrate is 0.6785g and the amount of manganese nitrate is 0.2088g. The remaining process steps and parameter settings are the same as in Example 1.
[0066] Comparative Example 2:
[0067] The difference between this comparative example and Example 1 is that in step 2, 1), the amount of nickel nitrate is 1.3571g and the amount of manganese nitrate is 0.2088g. The remaining process steps and parameter settings are the same as in Example 1.
[0068] The above description is merely a preferred embodiment of the present invention. These specific embodiments are different implementations based on the overall concept of the present invention, and the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A hybrid zinc-air battery, using a CuO@MnNi catalyst as the positive electrode, a zinc sheet as the negative electrode, and a KOH solution containing glucose as the electrolyte, characterized in that... The CuO@MnNi catalyst is obtained by a method for preparing a hybrid zinc-air battery cathode material, including: (1) Using a mixed aqueous solution of sodium hydroxide and ammonium persulfate as a pre-modification solution, copper foam was immersed in the pre-modification solution to obtain pre-modified copper foam, and CuO array substrate was obtained after heat treatment. (2) Using CuO array substrate as raw material, methanol as solvent, PVP as surfactant, and manganese nitrate and nickel nitrate as metal source, CuO@MnNi catalyst was prepared by solvothermal method, which is the positive electrode material of hybrid zinc-air battery.
2. The hybrid zinc-air battery according to claim 1, characterized in that, The glucose content in the electrolyte is 0.4~0.8 mol / L.
3. The hybrid zinc-air battery according to claim 1, characterized in that, (1) The concentration of sodium hydroxide in the pre-modified solution is 1.5~2.5 mol / L and the concentration of ammonium persulfate is 0.10~0.15 mol / L.
4. The hybrid zinc-air battery according to claim 1, characterized in that, (1) The immersion temperature is room temperature and the time is 3~12 min.
5. The hybrid zinc-air battery according to claim 1, characterized in that, (1) The volume ratio of copper foam to pre-modified liquid is 6 cm⁻¹ 2 250mL.
6. The hybrid zinc-air battery according to claim 1, characterized in that, (1) The heat treatment temperature is 200℃ and the time is 0.5~1.5h.
7. The hybrid zinc-air battery according to claim 1, characterized in that, (2) The reaction temperature of the solvothermal method is 160~180℃ and the time is 4~10h.