Rare earth element controlled MnCo2O4.5 oxygen evolution self-supporting electrode and application thereof

Abstract

The invention discloses a rare earth element controlled MnCo2O4.5 oxygen evolution self-supporting electrode and an application thereof. A nano array growth method is combined with a heat treatment two-step method to directly grow rare earth elements on a conductive substrate to regulate and control the MnCo2O4.5 nano array structure. The nano array growth method can realize preparation of the catalyst with high specific surface area and good electron transport performance, avoids use of a binder, significantly improves charge transport efficiency, and enhances the binding force of the catalyst and the substrate. Rare earth cations with small magnetic moment are introduced into MnCo2O4.5 to regulate and control the electron spinning state of Co, redistribution of charges is induced, the oxygen species adsorption / desorption capacity is optimized, and the reaction energy barrier is reduced. The nano array structure provides abundant active sites and rapid mass transfer channels, and rare earth doping synergistically improves the intrinsic activity and structural stability of the material. The preparation process provided by the invention is environment-friendly, has higher flexibility and controllability, and can meet the requirements of different application scenes.

Description

Technical Field

[0001] The present invention belongs to the field of electrocatalysis and relates to a method for regulating MnCo2O by rare earth elements. 4.5 Oxygen evolution self-supporting electrodes, especially rare earth element-regulated MnCo2O2, which achieves deep optimization of electronic structure through magnetic moment-spin state coupling effect. 4.5 Self-supporting electrodes for oxygen evolution and their applications. Background Art

[0002] With the acceleration of industrialization and urbanization, the extensive use of fossil fuels has led to serious environmental pollution and energy depletion. The development of clean and renewable energy has become a top priority. In the pursuit of sustainable energy solutions, the integration of water electrolysis with renewable energy has become a key strategy to achieve zero emissions. This integration addresses the intermittent challenges of solar and wind energy while promoting the production of green hydrogen, which is of great significance for the development and industrialization of fuel cell vehicles. Proton exchange membrane (PEM) electrolyzers are known for their high energy conversion efficiency, ability to produce high-purity gases, and compact design. However, the large-scale application of PEM electrolyzers is hindered by their reliance on expensive platinum group metal catalysts. Although non-precious metal-based catalysts have been reported as alternatives to acidic OER catalysts, these catalysts are easily dissolved and corroded in acidic environments, resulting in poor long-term durability, which greatly limits their practical application. Therefore, the development of efficient and stable non-precious metal acidic oxygen reduction catalysts has become both necessary and challenging.

[0003] In recent years, transition metal oxides (such as spinel Co3O4 and its derivatives) have attracted extensive attention due to their potential acidic OER activity. 4.5 By partially replacing the octahedral sites of cobalt, the stability of the catalyst can be improved. However, the existing technology still has key bottlenecks: for example, CN202311854070 discloses a method for preparing a rare earth element-doped cobalt manganese oxide-based catalyst, in which a precursor solution of rare earth metals, Mn and Co is coated on a substrate by a drop coating method, and the catalyst is prepared by multiple drop coatings and heat treatments. However, this method may cause uneven distribution of the catalyst on the substrate, making it difficult to form an ordered nanostructure, limiting the specific surface area and electron transfer efficiency, and affecting the activity and stability of the catalyst. In addition, as shown in the attached specification, Figure 2 It can be seen that the material phase still belongs to Co3O4.

[0004] In view of these challenges, innovative methods to improve the performance of MnCo2O are urgently needed. 4.5 The durability of spinel without impairing its activity under strongly acidic OER conditions. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of existing non-precious metal catalysts, the purpose of the present invention is to provide a rare earth element-regulated MnCo2O 4.5 Oxygen evolution self-supporting electrode and its application. This invention realizes deep optimization of electronic structure through multi-level collaborative design of "magnetic moment-spin state-nanoarray" and magnetic moment-spin state coupling effect (realized in the pulse electrodeposition step), breaking through the activity-stability trade-off problem of traditional strategies and achieving a performance leap of non-precious metal catalysts in acidic OER. 4.5 The introduction of rare earth cations with smaller magnetic moments changes the effective magnetic moment of cobalt, thereby changing the electronic spin state of cobalt, inducing charge redistribution, optimizing the adsorption / desorption ability of oxygen species, reducing the energy barrier of the reaction, and improving the electrical conductivity, promoting charge transfer during the reaction, accelerating the reaction rate, and greatly improving the stability without reducing its acidic OER activity. 4.5 Rare earth cations with different magnetic moments are introduced into the MnCo2O4.5. The magnetic moment of rare earth elements mainly comes from their unpaired 4f orbital electrons. The fewer the unpaired electrons, the smaller the magnetic moment. In the examples of the present invention, lanthanum with zero magnetic moment, samarium and neodymium with relatively low magnetic moments, and holmium with a high magnetic moment are introduced. By comparing the electrochemical properties of these MnCo2O4.5 electrodes with different magnetic moments, it was found that the electrodes with smaller magnetic moments have better catalytic activity and stability.

[0006] The nanoarray growth method can also achieve the preparation of catalysts with high specific surface area and good electron transport performance. Combined with the in-situ growth strategy of the substrate, the use of binders is avoided, the charge transfer efficiency is significantly improved, and the bonding force between the catalyst and the substrate is enhanced. The nanoarray structure provides abundant active sites and fast mass transfer channels, and rare earth doping synergistically improves the intrinsic activity and structural stability of the material. In addition, the pulse electrodeposition method can also precisely control the growth process of the catalyst to obtain a uniformly distributed nanoarray structure without the need for multiple coatings, thereby increasing the specific surface area and electron transport performance, thereby further improving the activity and stability of the catalyst. This solution, which combines the two-step method of nanoarray growth method and heat treatment through rare earth element regulation, not only solves the problem of insufficient catalyst activity and stability in the existing technology, but also brings unexpected technical effects, such as significantly improved catalytic activity and excellent stability.

[0007] The object of the present invention is achieved through the following technical solutions:

[0008] <First Aspect>

[0009] The present invention provides a rare earth element-regulated MnCo2O 4.5 The oxygen evolution self-supporting electrode is characterized in that the rare earth element-regulated MnCo2O 4.5The nanostructured nanoparticles are grown on a pre-treated conductive substrate by a nanoarray growth method combined with heat treatment.

[0010] As an embodiment of the present invention, the nanoarray growth method includes an electrochemical deposition method; using a precursor solution containing cobalt, manganese and rare earth metal ions as an electrochemical deposition solution, electrochemically depositing and growing rare earth element-controlled MnCo2O on a pretreated conductive substrate 4.5 Precursor; after annealing heat treatment and cooling, the precursor is obtained to obtain MnCo2O 4.5 Nanoarray-structured self-supporting electrode for oxygen evolution.

[0011] As one embodiment of the present invention, the electrochemical deposition includes pulse electrodeposition. Preferably, the pulse electrodeposition is performed in a three-electrode system. In some embodiments, the pulse electrodeposition is performed in a three-electrode system using the pretreated substrate as the working electrode, a platinum wire as the counter electrode, and Ag / AgCl as the reference electrode.

[0012] As one embodiment of the present invention, the parameters of the pulse electrodeposition are: the operating voltage of the external power supply is -1.5 to -1.1 V vs Ag / AgCl, the duty cycle is 20% to 50%, the frequency is 50 to 500 Hz, and the deposition time is 5 to 15 minutes. In some specific implementation examples, the operating voltage of the external power supply is -1.5 to -1.1 V vs Ag / AgCl, the duty cycle is 20%, the frequency is 200 Hz, and the deposition time is 10 minutes. If cyclic voltammetry deposition is used, impurities may be introduced due to the continuous change of the cyclic voltammetry potential, thereby affecting the catalyst performance.

[0013] As one embodiment of the present invention, the annealing heat treatment is carried out in an air atmosphere, with the temperature being increased to 200-350°C at a heating rate of 1-5°C / min and maintained at this temperature for 3-12 hours. In some specific implementation examples, the temperature is increased to 200-350°C at a heating rate of 5°C / min and maintained at this temperature for 12 hours. The pulse electrodeposition plus low-temperature annealing employed in the present invention is simple in process, reduces energy consumption by 50%, and is suitable for large-scale production.

[0014] As an embodiment of the present invention, the total metal ion concentration of the metal in the precursor solution is 1 to 5 mol L -1 The molar concentration of rare earth metals is 0 to 0.5 mol L -1 The molar concentration of rare earth metals can be 0.01 mol L -1 , 0.02 mol L -1 , 0.05 mol L -1 , 0.07 mol L -1 , 0.08 mol L-1 , 0.1 mol L -1 , 0.15 mol L -1 , 0.2 mol L -1 In some specific implementation examples, the total metal ion concentration is 3 mol L -1 The molar concentration of rare earth metals is 0.01 to 0.2 mol L -1 .

[0015] As an embodiment of the present invention, the conductive substrate is one of fluorine-doped tin oxide, indium tin oxide, carbon paper, carbon cloth, nickel foam and Pt / Ti.

[0016] As an embodiment of the present invention, the substrate pretreatment comprises ultrasonically cleaning the conductive substrate with anhydrous ethanol, isopropyl alcohol and water in sequence for 5 to 30 minutes; and drying the conductive substrate in a vacuum drying oven at 55 to 65° C. for 10 to 14 hours.

[0017] As an embodiment of the present invention, the cobalt source in the precursor solution is a cobalt salt; the cobalt salt is at least one of cobalt nitrate, cobalt acetylacetonate, cobalt acetate and cobalt carbonate.

[0018] As an embodiment of the present invention, the manganese source in the precursor solution is a manganese salt; the manganese salt is at least one of manganese nitrate, manganese acetylacetonate, manganese acetate and manganese carbonate.

[0019] As an embodiment of the present invention, the rare earth metal source in the precursor solution is a completely decomposable rare earth metal salt, including but not limited to nitrates, and also completely decomposable salts such as carbonates, acetates, and acetylacetonates of these rare earth metals.

[0020] As an embodiment of the present invention, the rare earth metal is at least one of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium. In some specific implementation examples, the rare earth metal salt is selected from nitrates, such as lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, samarium nitrate, europium nitrate, gadolinium nitrate, terbium nitrate, dysprosium nitrate, holmium nitrate, erbium nitrate, thulium nitrate, ytterbium nitrate, lutetium nitrate, and yttrium nitrate. The rare earth elements designed by the present invention regulate the MnCo2O 4.5 The regulation mechanism of the oxygen evolution self-supporting electrode is different from the existing technology, which regulates the electronic and coordination environment of the active site by introducing rare earth cations with different ionic radius and electronegativity, or utilizes the large ionic radius and small electronegativity characteristics of rare earth elements to induce severe distortion of the surface lattice of the selenide and improve the d-band center position of the surface nickel atomic site; the present invention achieves deep optimization of the electronic structure through the magnetic moment-spin state coupling effect.

[0021] As an embodiment of the present invention, the molar ratio of the cobalt salt, the manganese salt and the rare earth metal salt in the precursor solution is 2:0.8 to 1:0.2 to 0.01.

[0022] As one embodiment of the present invention, prior to electrochemical deposition, the pretreated conductive substrate is placed in the electrodeposition solution for immersion. Prior to using the catalyst support for electrochemical deposition, immersing the catalyst support in the electrodeposition solution facilitates the subsequent electrodeposition process, effectively improving the efficiency and quality of the electrodeposition process while promoting uniform distribution of metal ions on the catalyst support surface, thereby avoiding localized electrodeposition or surface unevenness.

[0023] Preferably, the infiltration process is accompanied by ultrasound, and the infiltration time is 5 to 15 minutes, for example, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes or 15 minutes, etc. The ultrasound power is 80 to 100 Hz.

[0024] As one embodiment of the present invention, after electrochemical deposition, the precursor is washed and dried.

[0025] Preferably, the drying method includes any one of forced air drying, vacuum drying or freeze drying, or a combination of at least two of them.

[0026] Preferably, the drying temperature is 60-90°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C or 90°C.

[0027] Preferably, the drying time is 12 to 24 hours, for example, it can be 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours or 24 hours.

[0028] As one embodiment of the present invention, after the annealing heat treatment, the oxygen-evolving self-supporting electrode is ultrasonically washed. Preferably, the ultrasonic washing time is 20 to 40 seconds, and the ultrasonic power is 80 to 100 Hz. This is to remove loosely adhered particles, and then the electrode is dried. Preferably, the drying method includes any one of forced air drying, vacuum drying, or freeze drying, or a combination of at least two. The drying temperature is 60 to 90°C, and the drying time is 12 to 24 hours.

[0029] In some specific implementation examples, a rare earth element is provided to regulate MnCo2O 4.5 The preparation method of the oxygen evolution self-supporting electrode comprises the following steps:

[0030] (1) Substrate pretreatment: ultrasonically clean the conductive substrate with anhydrous ethanol, isopropyl alcohol, and water for 5–30 min to remove surface oil, and then dry in a vacuum drying oven at 60 °C for 12 h.

[0031] (2) Preparing a precursor solution: Weigh appropriate amounts of cobalt salt, manganese salt, and rare earth metal salt, stir and dissolve them in an appropriate amount of deionized water, and the resulting precursor mixed solution is used as an electrodeposition solution;

[0032] (3) Nanoarray growth: Pulse electrodeposition was performed in a three-electrode system using the pretreated substrate as the working electrode, platinum wire as the counter electrode, and Ag / AgCl as the reference electrode. After completion, the electrodes were washed and dried.

[0033] (4) Heat treatment: The precursor obtained by pulse electrodeposition was annealed in air atmosphere, heated to 200-350°C at a heating rate of 5°C / min, kept at this temperature for 12 h, and naturally cooled to room temperature to obtain rare earth element-controlled MnCo2O 4.5 Self-supporting electrode for oxygen evolution.

[0034] The present invention uses a two-step method of nanoarray growth and heat treatment to synthesize rare earth element-regulated MnCo2O 4.5 The catalyst has a simple, safe and non-toxic synthesis process, and the catalyst is evenly distributed and in-situ grown on the substrate. The raw materials are directly prepared and sintered on the substrate, avoiding the use of binders, which enhances the MnCo2O 4.5 The contact between the catalyst and the substrate further stabilizes the catalyst.

[0035] <Second Aspect>

[0036] The present invention also provides the above rare earth element regulation MnCo2O 4.5 Application of oxygen evolution self-supporting electrodes in acidic oxygen evolution reactions, including oxygen evolution reactions in acidic water electrolysis.

[0037] As an embodiment of the present invention, the rare earth element regulates the MnCo2O 4.5 The application of the oxygen evolution self-supporting electrode in the acidic oxygen evolution reaction includes the following steps:

[0038] (1) The rare earth elements prepared above are used to regulate MnCo2O 4.5 The oxygen evolution self-supporting electrode was directly used as the working electrode, platinum wire was used as the counter electrode, and Ag / AgCl electrode was used as the reference electrode to construct a three-electrode system. The electrocatalytic oxygen evolution reaction was tested in an acidic solution.

[0039] (2) In the present invention, the acidic solution is preferably H2SO4 solution; the concentration of the acidic solution is 0.05 to 1.0 mol·L -1 , preferably 0.5 mol·L-1 ; The voltage of the electrocatalytic reaction is 1.0~2.0V.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) The rare earth elements provided by the present invention regulate MnCo2O 4.5 Oxygen evolution self-supporting electrode by adding MnCo2O 4.5 The introduction of rare earth cations with smaller magnetic moments changes the effective magnetic moment of cobalt, thereby changing the electronic spin state of cobalt and inducing charge redistribution. This not only optimizes the adsorption / desorption ability of oxygen species and reduces the energy barrier of the reaction, but also improves the conductivity, promotes charge transfer during the reaction, and accelerates the reaction rate, thus obtaining rare earth element-regulated MnCo2O with good conductivity and low intermediate adsorption energy. 4.5 The oxygen evolution self-supporting electrode system is environmentally friendly and non-toxic. 4.5 The catalyst has good performance in acidic water electrolysis and oxygen evolution reaction and excellent stability.

[0042] (2) The nanoarray growth method can achieve the preparation of catalysts with high specific surface area and good electron transport performance, avoid the use of binders, enhance the bonding strength between the catalyst and the substrate, and ensure the stability of the catalyst while maintaining a high catalyst loading. The pulse electrodeposition method can precisely control the deposition process to obtain a uniformly distributed nanoarray structure. At the same time, the deposition amount and catalyst size can be easily controlled by changing the electrodeposition parameters.

[0043] (3) The preparation process of the present invention is simple to operate, does not involve complex equipment, consumes less energy, has a short experimental cycle, and has the prospect of large-scale commercial production. At the same time, combined with the advantages of the nanoarray growth method, the preparation method of the present invention has higher flexibility and controllability, which can meet the needs of different application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0045] Figure 1 1 is the XRD pattern of Example 1 of the present invention and Comparative Example 1.

[0046] Figure 2 This is the SEM image of Example 1 of the present invention.

[0047] Figure 3 These are the OER polarization curves of Examples 1-4 of the present invention and Comparative Examples 1 and 2.

[0048] Figure 4 These are the OER polarization curves of Examples 1 and 5 of the present invention.

[0049] Figure 5 These are the stability curves of Example 1 of the present invention and Comparative Examples 1 and 2. DETAILED DESCRIPTION

[0050] The present invention will be described in detail below with reference to the examples. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that those skilled in the art may make several adjustments and improvements without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0051] Example 1

[0052] This embodiment is 10% Sm-MnCo2O 4.5 Catalyst preparation

[0053] (1) Pt / Ti was cut into 2 cm × 1 cm pieces and ultrasonically cleaned in ethanol, isopropanol, and deionized water for 30 min to remove surface oil. The pieces were then dried in a vacuum drying oven at 60 °C for 12 h.

[0054] (2) Weigh a certain amount of cobalt nitrate hexahydrate (0.2 mol), manganese nitrate tetrahydrate (0.09 mol), and samarium nitrate hexahydrate (0.01 mol) and dissolve them in 100 mL of deionized water to prepare a solution for later use. The total concentration of metal ions in the electrodeposition solution is 3 mol·L -1 , where the concentration of Sm is 0.1 mol·L -1 .

[0055] (3) The dried Pt / Ti electrode in step (1) was placed in the electrodeposition solution in step (2), and after ultrasonication for 10 minutes, it was taken out and used as a working electrode, a platinum wire electrode was used as a counter electrode, and an Ag / AgCl electrode was used as a reference electrode. Pulse electrodeposition was performed with a pulse potential of -1.1 V vs. Ag / AgCl, a duty cycle of 20%, a frequency of 200 Hz, and a deposition time of 10 minutes. After the electrodeposition was completed, the electrode was rinsed with deionized water and dried in a vacuum drying oven at 60°C for 12 hours.

[0056] (4) The catalyst precursor obtained in step (3) was placed in a muffle furnace for annealing, heated to 250°C at a heating rate of 5°C / min, kept warm for 12 hours, and cooled naturally to obtain 10% Sm-MnCo2O 4.5 Catalyst: ultrasonically place the catalyst in water for 20 to 40 seconds to remove loosely adhering particles, and then dry it.

[0057] Example 2

[0058] In this embodiment, 10% Nd-MnCo2O 4.5 Catalyst preparation

[0059] The difference between this embodiment and embodiment 1 is that neodymium nitrate hexahydrate is used instead of samarium nitrate hexahydrate.

[0060] Example 3

[0061] In this embodiment, 10% Ho-MnCo2O 4.5 Catalyst preparation

[0062] The difference between this embodiment and embodiment 1 is that holmium nitrate hexahydrate is used instead of samarium nitrate hexahydrate.

[0063] Example 4

[0064] In this embodiment, 10% La-MnCo2O 4.5 Catalyst preparation

[0065] The difference between this embodiment and embodiment 1 is that lanthanum nitrate hexahydrate is used instead of samarium nitrate hexahydrate.

[0066] Example 5

[0067] This embodiment is 10% Sm-MnCo2O 4.5 Catalyst preparation

[0068] This embodiment differs from embodiment 1 in that the heat treatment temperature is different. The heat treatment temperature is adjusted to 200°C, 300°C, and 350°C, respectively; the corresponding catalysts prepared are catalyst 5-1, catalyst 5-2, and catalyst 5-3.

[0069] Example 6

[0070] This embodiment is 20% Sm-MnCo2O 4.5 Catalyst preparation

[0071] The difference between this embodiment and embodiment 1 is that the doping ratio of Sm is changed to 20%, and the concentration of Sm in the electrodeposition solution is 0.2 mol·L -1 .

[0072] Comparative Example 1

[0073] This comparative example is MnCo2O 4.5 Catalyst preparation

[0074] The difference between this embodiment and embodiment 1 is that Sm is not doped.

[0075] Comparative Example 2

[0076] (1) Pt / Ti was cut into 2 cm × 1 cm pieces and ultrasonically cleaned in ethanol, isopropanol, and deionized water for 30 min to remove surface oil. The pieces were then dried in a vacuum drying oven at 60 °C for 12 h.

[0077] (2) Weigh a certain amount of cobalt nitrate hexahydrate (0.2 mol), manganese nitrate tetrahydrate (0.09 mol), and samarium nitrate hexahydrate (0.01 mol) and dissolve them in 100 mL of deionized water to prepare a precursor solution;

[0078] (3) 60 μL of the precursor solution was applied to the Pt / Ti substrate treated in step (1) by drop coating, placed on a heating table, slowly heated to 250°C, and reacted for 12 h; the Pt / Ti substrate after the above reaction was placed in water and ultrasonicated for 30 s, and 40 μL of the precursor solution was applied again by drop coating, placed on a heating table, slowly heated to 250°C, and reacted for 12 h; after the reaction, the substrate was ultrasonicated in deionized water again for 30 s, rinsed with deionized water after ultrasonication, and then dried in a vacuum drying oven at 60°C overnight to obtain a catalyst.

[0079] Performance Testing

[0080] The catalyst-loaded Pt / Ti prepared in each example and comparative example was used as a working electrode.

[0081] (1) The OER performance was measured in 0.5 M H2SO4 solution using a standard three-electrode system on a Coster electrochemical workstation. Platinum wire and Ag / AgCl (saturated KCl filling solution) electrodes were used as counter and reference electrodes, respectively. 4.5 The self-supporting oxygen evolution electrode was directly used as the working electrode. In 0.5M H2SO4 solution, the electrode was first charged at 100mV s between 1.0V and 1.8V. -1 Cyclic voltammetry (CV) was performed for 15 cycles and then at a scan rate of 5 mV s -1 LSV measurements were performed between 1.0 V and 2.0 V. The potentials measured for Ag / AgCl were converted to potentials relative to the reversible hydrogen electrode (RHE). The polarization curves of the performance were corrected for 80% ohmic impedance.

[0082] (2) Durability test: The test was carried out in 0.5M H2SO4 solution using a standard three-electrode system on a Coster electrochemical workstation. Platinum wire and Ag / AgCl (saturated KCl filling solution) electrodes were used as counter electrode and reference electrode respectively. 4.5 The self-supporting oxygen evolution electrode was directly used as the working electrode. In 0.5M H2SO4 solution, the electrode was first charged at 100mVs between 1.0V and 1.8V.-1 Cyclic voltammetry (CV) was performed for 30 cycles at a scan rate of 1.5 % and then the CV was activated at a current density of 200 mA cm -2 The constant current polarization test was carried out under the same conditions.

[0083] Figure 1 is the XRD pattern of Example 1 of the present invention and Comparative Example 1, Figure 1 It can be seen that the nanoarray growth method provided by the present invention combined with the two-step heat treatment method can successfully synthesize MnCo2O 4.5 Self-supported catalyst.

[0084] Figure 2 This is the SEM image of Example 1 of the present invention. It can be seen from the figure that a nano-array structure catalyst was successfully grown in situ on a conductive substrate through the nano-array growth method. Different from conventional structural designs such as particle stacking film and nanosheet structure, the rare earth element designed in the present invention regulates the MnCo2O 4.5 The structure of the oxygen evolution self-supporting electrode is a self-supporting nanoarray. This vertically arranged nanoarray can provide a directional electron transmission channel, thereby effectively reducing the oxygen evolution overpotential.

[0085] Figure 3 is the OER polarization curve diagram of Examples 1-4, Comparative Example 1 and Comparative Example 2, Figure 3 It can be seen that the regulation of rare earth elements, especially the addition of Sm, can improve the MnCo2O 4.5 The OER activity was as low as 250 mV.

[0086] Figure 4 The OER polarization curves of Example 1 and Example 5 are shown. The effects of different heat treatment temperatures on the activity of the nanoarray structure catalyst were studied, and it was determined that 200-250°C was the optimal heat treatment temperature.

[0087] Figure 5 The stability curves of Example 1, Comparative Example 1 and Comparative Example 2 of the present invention are shown in Figure 2. -2 Under high current density, the 10% Sm-MnCo2O prepared by the nanoarray growth method combined with low temperature annealing in the present invention is 4.5 The oxygen evolution self-supporting electrode can work stably for more than 600 hours (ie, Example 1), which is much longer than that of Comparative Examples 1 and 2. It can be seen that the rare earth element-regulated MnCo2O 4.5 The oxygen evolution self-supporting electrode exhibits excellent stability in acidic environment.

[0088] In summary, the present invention successfully prepared rare earth element-controlled MnCo2O on a conductive substrate by using a nanoarray growth method combined with high temperature annealing treatment. 4.5The oxygen evolution self-supporting electrode has a simple preparation process, is environmentally friendly, non-toxic and harmless, and further improves the activity and stability of the catalyst, achieving an overpotential as low as 250mV and a long-term charge of 600h@200mAcm in an acidic environment. -2 The preparation process provided by the present invention is environmentally friendly, has higher flexibility and controllability, and can meet the needs of different application scenarios.

[0089] The above description is merely a preferred embodiment and experimental example of the present invention and is not intended to limit the scope of protection of the present invention. It will be appreciated by those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A rare earth element regulates MnCo2O 4.5 The oxygen evolution self-supporting electrode is characterized in that The rare earth element-regulated MnCo2O 4.5 The nanostructured nanoparticles are grown on a pre-treated conductive substrate by a nanoarray growth method combined with heat treatment.

2. The rare earth element-regulated MnCo2O according to claim 1 4.5 The oxygen evolution self-supporting electrode is characterized in that The nanoarray growth method includes an electrochemical deposition method; using a precursor solution containing cobalt, manganese and rare earth metal ions as an electrochemical deposition solution, electrochemically depositing and growing rare earth element-controlled MnCo2O on a pretreated conductive substrate. 4.5 Precursor; after annealing heat treatment and cooling, the precursor is MnCo2O 4.5 Nanoarray-structured self-supporting electrode for oxygen evolution.

3. The rare earth element-regulated MnCo2O according to claim 2 4.5 The oxygen evolution self-supporting electrode is characterized in that The electrochemical deposition includes pulse electrodeposition; the parameters of the pulse electrodeposition are: the working voltage of the external power supply is -1.5 to -1.1 V vs Ag / AgCl, the duty cycle is 20% to 50%, the frequency is 50 to 500 Hz, and the deposition time is 5 to 15 minutes.

4. The rare earth element-regulated MnCo2O according to claim 2 4.5 The oxygen evolution self-supporting electrode is characterized in that The annealing heat treatment is carried out in an air atmosphere, with the temperature being raised to 200-350° C. at a heating rate of 1-5° C. / min, and the heat preservation treatment is carried out for 3-12 hours.

5. The rare earth element-regulated MnCo2O according to claim 2 4.5 The oxygen evolution self-supporting electrode is characterized in that The total metal ion concentration of the metal in the precursor solution is 1 to 5 mol L -1 The molar concentration of rare earth metals is 0 to 0.5 mol L -1 .

6. The rare earth element-regulated MnCo2O according to claim 2 4.5 The oxygen evolution self-supporting electrode is characterized in that Include at least one of the following technical features: A1. The conductive substrate is one of fluorine-doped tin oxide, indium tin oxide, carbon paper, carbon cloth, nickel foam and Pt / Ti; A2. Substrate pretreatment includes ultrasonic cleaning of the conductive substrate using anhydrous ethanol, isopropyl alcohol, and water in sequence for 5 to 30 minutes; and drying in a vacuum drying oven at 55 to 65°C for 10 to 14 hours. A3. The cobalt source in the precursor solution is a cobalt salt; the cobalt salt is at least one of cobalt nitrate, cobalt acetylacetonate, cobalt acetate and cobalt carbonate; A4. The manganese source in the precursor solution is a manganese salt; the manganese salt is at least one of manganese nitrate, manganese acetylacetonate, manganese acetate, and manganese carbonate; A5. The rare earth metal source in the precursor solution is a completely decomposable rare earth metal salt; the rare earth metal is at least one of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium, and the completely decomposable rare earth metal salt includes one or more of nitrate, carbonate, acetate, and acetylacetonate.

7. The rare earth element-regulated MnCo2O according to claim 6 4.5 The oxygen evolution self-supporting electrode is characterized in that The molar ratio of the cobalt salt, the manganese salt and the rare earth metal salt in the precursor solution is 2:0.8 to 1:0.2 to 0.

01.

8. The rare earth element-regulated MnCo2O according to claim 2 4.5 The oxygen evolution self-supporting electrode is characterized in that Include at least one of the following technical features: B1. Before electrochemical deposition, the pretreated conductive substrate is placed in the electrochemical deposition solution for infiltration; B2. After electrochemical deposition, the precursor is washed and dried; B3. After the annealing heat treatment is completed, the oxygen evolution self-supporting electrode is ultrasonically washed.

9. The rare earth element-regulated MnCo2O according to claim 8 4.5 The oxygen evolution self-supporting electrode is characterized in that The infiltration process is accompanied by ultrasound, and the infiltration time is 5 to 15 minutes; the drying temperature is 60 to 90° C., and the time is 12 to 24 hours; the ultrasonic water washing time is 20 to 40 seconds; and the ultrasonic power is 80 to 100 Hz.

10. A rare earth element-regulated MnCo2O according to any one of claims 1 to 9 4.5 Application of oxygen evolution self-supporting electrode in acidic oxygen evolution reaction.

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