Preparation method of carbon and nitrogen doped cobalt lanthanum oxide and application of carbon and nitrogen doped cobalt lanthanum oxide as electrocatalyst in electrocatalytic oxygen evolution

Abstract

The invention relates to the technical field of catalysis, in particular to a preparation method of a carbon and nitrogen doped cobalt-lanthanum oxide and application of the carbon and nitrogen doped cobalt-lanthanum oxide as an electrocatalyst in electrocatalytic oxygen evolution. The cobalt-lanthanum oxide is regulated and controlled in a calcination mode to prepare the heteroatom carbon and nitrogen doped cobalt-lanthanum oxide CoLaOx-CN; the band gap, conductivity and surface active sites of the material are changed by doping carbon and nitrogen. The electron density of the oxide is improved by nitrogen doping, and the electron conductivity and catalytic activity are enhanced. Carbon doping improves the surface hydrophobicity and stability of the material, and meanwhile, more active sites can be provided.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysis, and specifically, to a preparation method of carbon- and nitrogen-doped cobalt lanthanum oxide and its application as an electrocatalyst in electrocatalytic oxygen evolution. Background Art

[0002] Electrolytic water hydrogen production is one of the important technologies for realizing the conversion and utilization of clean energy. Among them, the oxygen evolution reaction (OER), as the key half-reaction, has problems such as slow kinetics and high overpotential, which limit the improvement of the overall electrolysis efficiency. Therefore, the development of efficient, stable and low-cost electrocatalysts has become the research focus in this field.

[0003] Currently, commercial oxygen evolution catalysts mainly represented by noble metal oxides (such as RuO 2 , IrO 2 ). Although they exhibit excellent catalytic performance, due to their high price and scarce resources, it is difficult to meet the requirements of large-scale industrial applications. Therefore, the research on cheap and efficient non-noble metal catalysts has become an important direction. Among them, cobalt-based and lanthanum-based oxides have received extensive attention due to their excellent redox properties and rich reserves.

[0004] Cobalt lanthanum oxide (CoLaO x ) as a bimetallic oxide material has high electrochemical activity and stability. However, its intrinsic catalytic activity is still limited, and the charge transfer efficiency is relatively low, resulting in the need for further optimization of the oxygen evolution performance. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a preparation method of carbon- and nitrogen-doped cobalt lanthanum oxide and its application as an electrocatalyst in electrocatalytic oxygen evolution.

[0006] The first object of the present invention is to provide a preparation method of carbon- and nitrogen-doped cobalt lanthanum oxide, including the following steps: The technical solution of the present invention to solve the above technical problems is as follows: A preparation method of carbon- and nitrogen-doped cobalt lanthanum oxide, including the following steps: S1. Dissolve cobalt acetylacetonate, lanthanum acetylacetonate and melamine in a mixed solution of ethanol and ultrapure water, stir, centrifuge and dry.

[0007] S2. Heat the product obtained in step (1) to obtain the product carbon- and nitrogen-doped cobalt lanthanum oxide, labeled as CoLaO x -CN.

[0008] Further, the temperature of the high-temperature calcination in Step 2 is 100 - 300 °C. If the calcination temperature is too low (<100 °C), the organic components and impurities in the precursor cannot be effectively decomposed, and carbon- and nitrogen-doped cobalt lanthanum oxide cannot be formed. If the calcination temperature is too high (>300 °C), it may lead to the loss of carbon and nitrogen, reducing the doping effect. At the same time, it may cause excessive growth of oxide grains, affecting the specific surface area and activity of the material. The optimized calcination temperature range of 100 - 300 °C can achieve the decomposition of the organic precursor and promote the formation of the oxide, while retaining the doped carbon and nitrogen elements.

[0009] Further, the calcination time is 180 minutes. The calcination time determines the completeness of the reaction. 180 minutes provides sufficient time for the uniform distribution of carbon and nitrogen doping in the cobalt lanthanum oxide lattice and ensures the formation of the crystal structure of the oxide. Too short a time may lead to incomplete reactions, and too long a time may result in a decrease in the carbon and nitrogen doping concentration or too large oxide particles.

[0010] Further, in Step 1, the mass ratio of cobalt acetylacetonate to lanthanum acetylacetonate is 210:(15 - 100). This ratio determines the relative ratio of cobalt and lanthanum in the final product, which in turn affects the crystal structure and catalytic activity of cobalt lanthanum oxide. Too high a mass of lanthanum acetylacetonate will reduce the electrocatalytic performance, and too low a mass will affect the structural stability and conductivity of the material.

[0011] Further, the addition amount of melamine is 50 - 150 mg. Melamine is the source of carbon and nitrogen, and its addition amount directly determines the doping amount of carbon and nitrogen in the final product. Too low an addition amount results in insufficient doping and cannot significantly improve the conductivity and catalytic activity of the oxide. Too high an addition amount causes excessive doping of carbon and nitrogen, leading to damage to the crystal structure of the oxide and a decline in material performance.

[0012] Further, the volume ratio of ethanol to ultrapure water in the mixed solution is 7:1, and the addition amount of the mixed solution is limited to 4 mL of the mixed solution per 7 mg of cobalt acetylacetonate. Ethanol has good organic solvent properties and can dissolve cobalt acetylacetonate, lanthanum acetylacetonate, and melamine, enabling the uniform dispersion of each component in the reaction system. Ultrapure water provides a trace polar environment, which helps to improve the stability of the solution and promote the interaction between precursors. The volume ratio of 7:1 ensures that the solution has good dissolution ability and can improve the uniformity and morphology quality of the product during subsequent centrifugation and drying processes.

[0013] The present invention also provides the application of the carbon- and nitrogen-doped cobalt lanthanum oxide as an electrocatalyst in the electrocatalytic oxygen evolution reaction.

[0014] The present invention also provides a preparation method for a modified electrode of the carbon- and nitrogen-doped cobalt lanthanum oxide electrocatalyst, including the following steps: (1) Weigh 3 mg of CoLaO x -CN powder, transfer 400 μL of absolute ethanol, 100 μL of water and 10 μL of Nafion solution, and ultrasonically disperse them evenly for 25 min to prepare a catalyst suspension; (2) Polish the bare glassy carbon electrode with alumina powder. After cleaning, coat 5 μL of CoLaO x -CN solution on the bare glassy carbon electrode, and obtain a carbon, nitrogen-doped cobalt lanthanum oxide electrocatalyst modified electrode after drying.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The CoLaOx-CN synthesized in the present invention is composed of oxides of Co and La, and the band gap, conductivity and surface active sites of the material are changed by doping with carbon and nitrogen. Nitrogen doping improves the electron density of the oxide, which helps to enhance the electron conductivity and catalytic activity. Carbon doping improves the surface hydrophobicity and stability of the material, and may also provide more active sites.

[0016] In the present invention, heteroatom carbon and nitrogen-doped cobalt lanthanum oxide is prepared by calcining cobalt lanthanum oxide. In an alkaline solution, when the current density is 10 mA·cm -2 , the overpotential of the prepared carbon, nitrogen-doped cobalt lanthanum oxide is 297 mV, and the Tafel slope is 106 mV·dec -1 . The results show that CoLaO x -CN exhibits excellent catalytic performance for the oxygen evolution reaction in an alkaline environment. The doping of carbon and nitrogen heteroatoms and the existence of a large number of oxygen vacancies not only greatly improve the conductivity of the CoLaO x -CN electrocatalyst, but also promote the exposure of more active sites, thus significantly enhancing the oxygen evolution reaction performance of the synthesized nanomaterial in an alkaline environment. Description of the Drawings

[0017] Figure 1 SEM image of the CoLaO x -CN catalyst prepared in Example 1; Figure 2 Energy dispersive spectroscopy diagram of the CoLaO x -CN catalyst prepared in Example 1; Figure 3 Linear voltammetry scanning curve of the CoLaO x -CN catalyst prepared in Examples 1-3 in 1 mol·L -1 sodium hydroxide solution; Figure 4 Linear voltammetry scanning curve of the CoLaO x -CN catalyst prepared in Examples 1-3 in 1 mol·L-1 Tafel slope curve in sodium hydroxide solution; Figure 5 CoLaO prepared for Examples 1, 4, and 5 x -CN catalyst electrode in 1 mol·L -1 Linear voltammetry scan curve in sodium hydroxide solution; Figure 6 CoLaO prepared for Examples 1, 4, and 5 x -CN catalyst electrode in 1 mol·L -1 Tafel slope curve in sodium hydroxide solution; Figure 7 CoLaO prepared for Examples 1, 6 - 9 x -CN catalyst electrode in 1 mol·L -1 Linear voltammetry scan curve in sodium hydroxide solution; Figure 8 CoLaO prepared for Examples 1, 6 - 9 x -CN catalyst electrode in 1 mol·L -1 Tafel slope curve in sodium hydroxide solution; Figure 9 For CoLaO x -CN, CoLaO, CoO-CN, LaO-CN, CoO, LaO, GCE modified electrodes in 1 mol·L -1 Linear sweep voltammetry curve in sodium hydroxide solution; Figure 10 For LaO-CN, LaO modified electrodes in 1 mol·L -1 Linear sweep voltammetry curve in sodium hydroxide solution; Figure 11 For CoO, CoO-CN, CoLaO, CoLaO x -CN Tafel slope curve; Figure 12 For CoLaO x -CN, CoLaO, CoO-CN, LaO-CN, CoO, LaO, GCE in 1 mol·L -1 Electrochemical impedance spectroscopy curve in sodium hydroxide solution; Figure 13 For CoO in 1 mol·L -1 Cyclic voltammetry curves at different scan rates in sodium hydroxide solution; Figure 14 For LaO in 1 mol·L -1 Cyclic voltammetry curves at different scan rates in sodium hydroxide solution; Figure 15 Cyclic voltammograms of CoLaO in 1 mol·L -1 sodium hydroxide solution at different scan rates; Figure 16 Cyclic voltammograms of CoO-CN in 1 mol·L -1 sodium hydroxide solution at different scan rates; Figure 17 Cyclic voltammograms of LaO-CN in 1 mol·L -1 sodium hydroxide solution at different scan rates; Figure 18 Cyclic voltammograms of CoLaO x -CN in 1 mol·L -1 sodium hydroxide solution at different scan rates; Figure 19 Cyclic voltammograms of CoO, LaO, CoLaO, CoO-CN, LaO-CN, CoLaO x -CN at the current density difference at 0.8153 V (vs. RHE) and the linear fitting curve graph of the scan rate. Detailed implementation manners

[0018] Example 1 A preparation method of carbon and nitrogen co-doped cobalt lanthanum oxide, comprising the following steps: (1) First, weigh 210 mg of cobalt acetylacetonate, 30 mg of lanthanum acetylacetonate and 100 mg of melamine, disperse them into a mixed solution of 105 mL of ethanol and 15 mL of ultrapure water, stir for 24 hours, then centrifuge, and put the obtained substance into a blast drying oven for drying.

[0019] (2) Transfer the product obtained in step (1) to a porcelain crucible, calcine it at a temperature of 200 °C in a muffle furnace for 180 min to obtain a product of carbon and nitrogen co-doped cobalt lanthanum oxide.

[0020] The carbon and nitrogen co-doped cobalt lanthanum oxide prepared in Example 1 was characterized by scanning electron microscopy (SEM), and the results are shown in Figure 1 . The carbon and nitrogen co-doped cobalt lanthanum oxide prepared in Example 1 was characterized by energy dispersive spectroscopy, as shown in Figure 2 , showing the presence of elements cobalt, lanthanum, oxygen, carbon and nitrogen in the material.

[0021] Example 2 The difference between Example 2 and Example 1 is that the calcination temperature is 100 °C, and the other conditions are exactly the same, marked as CoLaO x -CN-100.

[0022] Example 3 Example 3 differs from Example 1 in that the calcination temperature is 300 °C, and the other conditions are exactly the same, labeled as CoLaO x -CN-300.

[0023] Example 4 Example 4 differs from Example 1 in that the addition amount of melamine is 50 mg, and the other conditions are exactly the same, labeled as CoLaO x -50CN.

[0024] Example 5 Example 5 differs from Example 1 in that the addition amount of melamine is 150 mg, and the other conditions are exactly the same, labeled as CoLaO x -150CN.

[0025] Example 6 Example 6 differs from Example 1 in that the amount of lanthanum acetylacetonate is 15 mg, and the other conditions are exactly the same, labeled as Co 210 La 15 O x -CN.

[0026] Example 7 Example 7 differs from Example 1 in that the amount of lanthanum acetylacetonate is 45 mg, and the other conditions are exactly the same, labeled as Co 210 La 45 O x -CN.

[0027] Example 8 Example 8 differs from Example 1 in that the amount of lanthanum acetylacetonate is 60 mg, and the other conditions are exactly the same, labeled as Co 210 La 60 O x -CN.

[0028] Example 9 Example 9 differs from Example 1 in that the amount of lanthanum acetylacetonate is 100 mg, and the other conditions are exactly the same, labeled as Co 210 La 100 O x -CN.

[0029] Perform an electrochemically decomposed water oxygen evolution activity test on the oxides prepared in Examples 1-9: (1) Prepare a modified electrode using the oxides prepared in Examples 1-9. The preparation method includes the following steps: S1. Weigh 3 mg of the oxide powder prepared in Examples 1-9, transfer 400 μL of absolute ethanol, 100 μL of water, and 10 μL of Nafion solution, and ultrasonically disperse them evenly for 25 min to prepare a catalyst suspension; S2. After polishing the bare glassy carbon electrode with alumina powder and cleaning it, 5 μL of CoLaO x -CN solution was coated on the bare glassy carbon electrode, and after drying, a carbon, nitrogen-doped cobalt lanthanum oxide electrocatalyst modified electrode was obtained.

[0030] (2) Test method: All electrochemical tests were carried out on a CHI760E electrochemical workstation and were carried out with a three-electrode system as the test system. The bare glassy carbon electrode modified with the catalyst was used as the working electrode, the platinum electrode was used as the counter electrode, and the silver-silver chloride electrode was used as the reference electrode in 1 mol·L -1 sodium hydroxide solution for the oxygen evolution reaction of electrolytic water.

[0031] (3) Test results Influence of calcination temperature on the catalytic performance of CoLaO x -CN: The test results of the electrochemical performance of the modified electrodes prepared by using the oxides prepared in Examples 1-3 are as Figure 3 and Figure 4 shown. At a current density of 10 mA·cm -2 , the overpotentials of the modified electrodes prepared in Example 2, Example 1, and Example 3 are 342 mV, 297 mV, and 314 mV respectively, and the corresponding Tafel slopes are 133 mV·dec -1 , 106 mV·dec -1 , 121 mV·dec -1 . At a temperature of 200 °C, CoLaO x -CN-200 has a smaller overpotential and a lower Tafel slope.

[0032] Influence of the amount of melamine added on the catalytic performance of CoLaO x -CN: The test results of the electrochemical performance of the modified electrodes prepared by using the oxides prepared in Example 1, Example 4, and Example 5 are as Figures 5-6 shown. The overpotentials of the modified electrodes prepared in Example 4, Example 1, and Example 5 at a current density of 10 mA·cm -2 are 380 mV, 297 mV, and 341 mV in sequence, and the corresponding Tafel slopes are 141 mV·dec -1 , 106 mV·dec -1 and 130 mV·dec -1 . When the amount of melamine is 100 mg, the modified electrode at this time has a smaller overpotential and a lower Tafel slope.

[0033] Influence of the amount of lanthanum acetylacetonate added on CoLaOx - Influence on the catalytic performance of -CN: Fix the amount of cobalt acetylacetonate at 210 mg, and change the amount of lanthanum acetylacetonate to 15 mg (Example 6), 30 mg (Example 1), 45 mg (Example 7), 60 mg (Example 8), 100 mg (Example 9) respectively. That is, the ratios of cobalt acetylacetonate to lanthanum acetylacetonate are 14:1, 7:1, 14:3, 7:2, 21:10 respectively. Keep other conditions unchanged, the calcination temperature is 200 °C, and the holding time is 180 min. Finally, CoLaO -CN electrocatalysts with different cobalt - lanthanum ratios are obtained. x - The test results of the electrochemical performance of the modified electrode are as Figures 7-8 shown. At a current density of 10 mA·cm -2 , the overpotentials corresponding to the obtained modified electrodes are 300 mV, 297 mV, 350 mV, 340 mV, and 310 mV respectively, and the corresponding Tafel slopes are 144 mV·dec -1 , 106 mV·dec -1 , 137 mV·dec -1 , 85 mV·dec -1 and 101 mV·dec -1 . By comparison, it can be concluded that when the mass ratio of cobalt acetylacetonate to lanthanum acetylacetonate is 7:1, that is, when the amount of lanthanum acetylacetonate is 30 mg, the obtained modified electrode has the lowest overpotential and a relatively low Tafel slope, and the performance of the catalyst material is the best under this condition.

[0034] Comparative Example 1 The preparation method of CoLaO is as follows: (1) First, weigh 210 mg of cobalt acetylacetonate and 30 mg of lanthanum acetylacetonate, disperse them in a mixed solution of 105 mL of ethanol and 15 mL of ultrapure water, stir for 24 hours, then centrifuge it, and put the obtained substance into a blast drying oven for drying.

[0035] (2) Transfer the product obtained in step (1) to a porcelain crucible, and calcine it at 200 °C in a muffle furnace for 180 min to obtain a product of cobalt - lanthanum oxide, labeled as CoLaO.

[0036] Comparative Example 2 The preparation method of CoO - CN is as follows: (1) First, weigh 210 mg of cobalt acetylacetonate and 100 mg of melamine, disperse them in a mixed solution of 105 mL of ethanol and 15 mL of ultrapure water, stir for 24 hours, then centrifuge it, and put the obtained substance into a blast drying oven for drying.

[0037] (2) Transfer the product obtained in step (1) to a porcelain crucible and calcine it in a muffle furnace at a temperature of 200 °C for 180 min to obtain a carbon and nitrogen-doped cobalt oxide product, labeled as CoO x -CN.

[0038] Comparative Example 3 The preparation method of LaO-CN is as follows: (1) First, weigh 30 mg of lanthanum acetylacetonate and 100 mg of melamine, disperse them in a mixed solution of 105 mL of ethanol and 15 mL of ultrapure water, stir for 24 hours, then centrifuge it, and place the obtained substance in a blast drying oven for drying.

[0039] (2) Transfer the product obtained in step (1) to a porcelain crucible and calcine it in a muffle furnace at a temperature of 200 °C for 180 min to obtain a carbon and nitrogen-doped lanthanum oxide product, labeled as LaO-CN.

[0040] Comparative Example 4 The preparation method of CoO is as follows: Weigh 210 mg of cobalt acetylacetonate, transfer it to a porcelain crucible, and calcine it in a muffle furnace at a temperature of 200 °C for 180 min to obtain a cobalt oxide product, labeled as CoO.

[0041] Comparative Example 5 The preparation method of LaO is as follows: Weigh 210 mg of lanthanum acetylacetonate, transfer it to a porcelain crucible, and calcine it in a muffle furnace at a temperature of 200 °C for 180 min to obtain a lanthanum oxide product, labeled as LaO.

[0042] Test the linear sweep voltammetry curves of the glassy carbon electrodes modified with the catalysts obtained in Test Example 1 and Comparative Examples 1-5 in 1 mol·L -1 sodium hydroxide solution, as Figures 9-10 shown, the curves of LaO-CN and LaO are almost horizontal, indicating that LaO and LaO-CN themselves have relatively low electrocatalytic activities. The overpotential of CoLaO is less than that of CoO, indicating that metal alloys often have more excellent catalytic performance than single metals due to their unique structures and metal-metal interactions. Among them, CoLaO x -CN, CoLaO, CoO-CN, and CoO electrodes have overpotentials of 297 mV, 313 mV, 320 mV, and 326 mV, respectively, at a current density of 10 mA·cm -2 . The higher the overpotential, the worse the catalytic activity, indicating that the catalytic activity of Co itself is poor. Adding melamine and lanthanum elements can well improve its catalytic activity. However, to reach the same current density, CoLaO x-CN requires a smaller overpotential than CoLaO, CoLaO x -CN is superior to most cobalt-lanthanum-based electrocatalysts (Table 1), because carbon-nitrogen doping can adjust its chemical properties to obtain active sites, increase the electron density at the Fermi level and enhance the stability of the material.

[0043] Table 1 Comparison of OER performance of other recent cobalt / lanthanum-based catalysts

[0044] According to Figure 9 the data in the linear sweep voltammetry curve, the corresponding Tafel slopes of the four main catalysts were obtained. It can be seen from Figure 11 that the Tafel slopes of CoLaO, CoO, CoO-CN, CoLaO x -CN are 123 mV·dec -1 , 110 mV·dec -1 , 108 mV·dec -1 , 106 mV·dec -1 respectively, and the Tafel slopes decrease in turn. The lower the Tafel slope, the faster the reaction kinetics proceeds. Consistent with the results obtained from the linear sweep voltammetry curve, the Tafel slope of CoLaO x -CN is the smallest, indicating that the addition of melamine is beneficial to the oxygen evolution reaction and can thus well promote the catalytic effect and improve the oxygen evolution efficiency.

[0045] To study the charge transfer rate of the electrocatalyst, electrochemical impedance spectroscopy (EIS) was carried out, and the experimental results are as Figure 12 shown. It can be seen from Figure 12 that the arc diameters of the CoO, CoLaO, CoO-CN, CoLaO x -CN modified electrodes decrease in turn, that is, the charge transfer resistance decreases in turn. Among them, the arc diameter of the CoLaO x -CN catalyst is the smallest, that is, the charge transfer resistance is the smallest, indicating that the CoLaO x -CN has the fastest charge transfer rate. The radii of CoO and CoLaO are much larger than those of CoLaO x -CN, indicating that they have large resistance and poor conductivity. The charge transfer resistance of CoLaO x -CN is smaller than that of CoO-CN and LaO-CN, indicating that the synergistic effect between cobalt and lanthanum metals makes the CoLaO x -CN catalyst have good conductivity. The charge transfer resistance of CoLaO x -CN is smaller than that of CoLaO, indicating that carbon-nitrogen doping optimizes the structure of the material, reduces the resistance, improves the mass transfer rate, and the existence of oxygen vacancies also promotes the charge transfer during the oxygen evolution reaction.

[0046] The prepared different catalysts were tested for their electrochemical performance by cyclic voltammetry at different scanning rates, and the obtained results are as Figures 13-18 shown. To deeply evaluate the electrochemical performance of these catalysts, the current density difference at a potential of 0.8135 V (vs. RHE) was calculated and plotted against the corresponding scanning rate to obtain Figure 19 . Taking the obtained difference as the ordinate and the scanning rate as the abscissa, the double-layer capacitance value was obtained from the slope after linear fitting, as Figure 19 shown. The capacitances of CoLaO x -CN, CoO-CN, CoO, CoLaO, LaO-CN, and LaO are 6.38 mF·cm -2 , 5.87 mF·cm -2 , 6.08 mF·cm -2 , 1.08 mF·cm -2 , 4.96 mF·cm -2 , and 5.44 mF·cm -2 . The results show that the CoLaO x -CN catalyst has the largest capacitance value, indicating that it has the largest electrochemical active area and more active sites. This also proves that the structure of CoLaO x -CN nanomaterial doped with melamine has more active sites, and the abundant active sites are beneficial to the improvement of electrocatalytic oxygen evolution performance.

[0047] References [1] Baosharile Aodu, Li Xin. Influence of Iron-Cobalt Ratio on the Morphology and Oxygen Evolution Reaction Activity of Carbon Materials [J / OL]. Industrial Catalysis: 1-11 [2024-05-13]. http: / / kns.cnki.net / kcms / detail / 61.1233.TQ.20240418.1535.002.html. [2] Chen Yuefei, Xiao Ke, Wang Chaoyang, et al. Research Progress of Electrocatalytic Water Splitting Catalysts [J]. Chemical Engineering of Oil & Gas, 2024, 53(02):62-70. [3] Hou Pengfei, Shan Xiaoyong, Bai Jianming. Latest Progress of Nickel-Based Oxygen Evolution Catalytic Materials for Alkaline Water Electrolysis [J]. Industrial Catalysis, 2024, 32(04):18-29. [4] Zhang M, Zhang J, Ran S, et al. A robust bifunctional catalystforrechargeable Zn-air batteries: Ultrathin NiFe-LDH nanowalls verticallyanchored on soybean-derived Fe-N-C matrix. Nano Res, 2020, 14: 1175–1186 [5] Lyu D, Yao S, Ali A, et al. N,S-codoped carbon matrix-encapsulatedCo9S8 nanoparticles as a highly efficient and durablebifunctional oxygen redox electrocatalyst for rechargeable Zn-air batteries.Adv Energy Mater, 2021, 11:2101249。

Claims

1. A method for preparing carbon- and nitrogen-doped cobalt lanthanum oxide, characterized in that: The following steps are involved: S1, dispersing cobalt acetylacetonate, lanthanum acetylacetonate and melamine in a mixed solution of ethanol and ultrapure water, stirring, centrifuging and drying; S2. The product obtained in step (1) is calcined at high temperature to obtain carbon- and nitrogen-doped cobalt lanthanum oxide, which is labeled as CoLaO x -CN.

2. The method for preparing carbon- and nitrogen-doped cobalt lanthanum oxide according to claim 1, characterized in that: The temperature of high temperature calcination in step 2 is 100-300°C.

3. The method for preparing carbon- and nitrogen-doped cobalt lanthanum oxide according to claim 1, characterized in that: The high temperature calcination time in step 2 is 180 minutes.

4. The method for preparing carbon- and nitrogen-doped cobalt lanthanum oxide according to claim 1, characterized in that: In step 1, the mass ratio of cobalt acetylacetonate to lanthanum acetylacetonate is 210:(15-100).

5. The method for preparing carbon- and nitrogen-doped cobalt lanthanum oxide according to claim 1, characterized in that: The amount of melamine added is 50-150 mg.

6. The method for preparing carbon- and nitrogen-doped cobalt lanthanum oxide according to claim 1, characterized in that: The volume ratio of ethanol to ultrapure water in the mixed solution is 7:1, and the amount of the mixed solution added is limited to 4 ml of the mixed solution for every 7 mg of cobalt acetylacetonate.

7. Use of carbon- and nitrogen-doped cobalt lanthanum oxide prepared by the preparation method according to any one of claims 1 to 6 as an electrocatalyst in an electrocatalytic oxygen evolution reaction.

8. The use of the carbon- and nitrogen-doped cobalt lanthanum oxide according to claim 7 as an electrocatalyst in an electrocatalytic oxygen evolution reaction, characterized in that: The method for preparing the carbon and nitrogen doped cobalt lanthanum oxide electrocatalyst modified electrode comprises the following steps: (1) Weigh 3 mg CoLaO x -CN powder, pipette 400 μL of anhydrous ethanol, 100 μL of water and 10 μL of Nafion solution, and disperse evenly under ultrasonication for 25 min to prepare a catalyst suspension; (2) The bare glassy carbon electrode was polished with alumina powder and cleaned. Then 5 μL of CoLaO x -CN solution was coated on a bare glassy carbon electrode, and after drying, a carbon and nitrogen doped cobalt lanthanum oxide electrocatalyst modified electrode was obtained.

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