Perovskite-based composite catalysts in-situ loaded with cobalt-iron-nickel alloy, preparation and application in OER catalysis

Abstract

The application belongs to the field of OER catalysis, and specifically discloses a preparation method of a perovskite-based composite catalyst of surface in-situ desolventized cobalt-iron-nickel ternary alloy nanoparticles. 1‑x BO 3‑δ The perovskite precursor material with a structural formula of A 1‑x BO 3‑δ , wherein A is an alkaline earth or rare earth metal element, B includes Co, Fe and Ni, and 0.85<=x<1. The application also includes the catalyst prepared by the preparation method and OER catalytic application thereof. The preparation method can be used for preparing a material with special physicochemical properties and structure and excellent OER catalytic activity.

Description

Technical Field

[0001] This invention belongs to the field of catalytic water splitting technology, specifically relating to the field of OER catalytic materials for water electrolysis. Background Technology

[0002] The growth in global energy demand is often a sign of a thriving socio-economic development. While fossil fuels have brought convenience to our lives, their excessive consumption has had a significant negative impact on the environment. The rational utilization and effective conversion of energy have become two crucial issues in the development of the energy industry today, and the exploration of renewable energy is of significant strategic importance to the sustainable development of society. Hydrogen energy, as an ideal, green, and efficient renewable energy source, boasts high calorific value, abundant sources, environmental friendliness, and wide applicability, and is receiving increasing attention in many national and international strategies. Hydrogen production via water electrolysis produces hydrogen with pure oxygen as the only byproduct. From an environmental and sustainable development perspective, water electrolysis is currently the optimal method for hydrogen production. The oxygen evolution reaction (OER) at the anode of water electrolysis involves multiple proton (H+) reactions. + The oxygen evolution reaction (OER) process is kinetically slow and is the most energy-intensive step in water electrolysis. Therefore, developing green, inexpensive, efficient, and highly stable OER catalysts has become an important issue in the current energy field.

[0003] Perovskite oxides have become a research hotspot in OER catalysts in recent years due to their flexible and stable crystal structure and unique physicochemical properties. The general structural formula of perovskite oxides is ABO3, where the A-site is usually an alkaline earth or rare earth metal element, and the B-site is generally a transition metal element with multiple valence states. The metal ion at the A-site plays a role in stabilizing the crystal structure, while the transition metal ion at the B-site, with its variable valence state, endows the material with special physicochemical properties. However, the relatively low electronic conductivity and intrinsic catalytic activity of perovskite oxides pose a challenge in catalyst research.

[0004] Currently, combining perovskite catalysts with alloy particles possessing high electrical conductivity for the oxygen evolution reaction (OER) in water electrolysis is one of the important approaches to improving its OER activity. Interactions occur at the two-phase interface, altering the electronic structure of the perovskite oxide. A unique synergistic effect enhances the catalyst's conductivity, resulting in composite materials exhibiting superior catalytic activity compared to their single-component counterparts. However, current methods for preparing composite catalysts of perovskite oxides and active materials generally employ traditional methods such as vapor deposition, ball milling, and wet chemical impregnation. These methods struggle to precisely control the size and density of surface metal nanoparticles, and the interactions between the perovskite matrix and metal nanoparticles in the prepared catalyst materials are relatively weak. In practical applications, metal nanoparticles inevitably aggregate at high temperatures, often shortening the catalyst's lifespan.

[0005] In response to the aforementioned technical shortcomings, a few improved solutions for solution removal preparation have recently been proposed in the industry. Although these solutions can improve the results to some extent, the existing solution removal methods are still immature. Most of them need to be carried out at high temperatures, making it difficult to effectively control the physicochemical characteristics, dispersion, and bonding ability of alloy particles with the substrate. This makes it difficult to effectively leverage the advantages of solution removal methods, and the OER performance of the prepared materials still needs to be further improved. Summary of the Invention

[0006] To address the issue of unsatisfactory OER activity and stability of existing perovskite-based composite catalysts, the primary objective of this invention is to provide a method for preparing a perovskite-based composite catalyst (also referred to as an in-situ supported perovskite-based composite catalyst or perovskite-based composite catalyst) using in-situ desolvation-supported cobalt-iron-nickel ternary alloy nanoparticles. This method aims to prepare a material with unique composition and structural characteristics, exhibiting excellent OER activity and cycle stability.

[0007] The second objective of this invention is to provide a perovskite-based composite catalyst prepared by the aforementioned method.

[0008] The third objective of this invention is the application of the perovskite-based composite catalyst as an OER catalyst, and an electrolytic water device containing the perovskite-based composite catalyst and its anode catalyst.

[0009] A method for preparing a perovskite-based composite catalyst using cobalt-iron-nickel ternary alloy nanoparticles with in-situ surface desolvation, yielding an A-site defect expressed as A. 1-x BO 3-δ The perovskite precursor material is then calcined in a hydrogen-containing atmosphere at a temperature of 340–410°C to obtain the product.

[0010] The A mentioned 1-x BO 3-δ In this context, A represents alkaline earth or rare earth metal elements, B includes Co, Fe, and Ni, 0.85 ≤ x < 1, and δ represents the number of oxygen lattice defects.

[0011] This invention innovatively uses the expression for the defect at position A as A. 1-x BO 3-δ Using perovskite as a precursor substrate, and further coordinating with the temperature control of subsequent hydrogen-containing calcination, a synergistic effect can be achieved, enabling the unexpected in-situ precipitation of Co-Fe-Ni ternary alloy particles at the specified temperature, thereby improving their dispersion uniformity and their physical and chemical bonding with the substrate. This synergistically improves the OER activity and catalytic stability of the prepared material.

[0012] In this invention, the combined control of A (the defective substrate) and temperature under a hydrogen-containing atmosphere is key to synergistically inducing the in-situ desolvation and precipitation of the ternary alloy particles, improving their dispersion and in-situ bonding stability, and enhancing their OER activity and stability.

[0013] In this invention, the expression for the A-site defect is A. 1-x BO 3-δ The perovskite can be prepared using existing methods, preferably by a sol-gel method. The steps are as follows: mixing stoichiometric amounts of source A, source B and complexing agent to carry out a sol-gel reaction, followed by foaming and aging to obtain a dry gel, and then performing oxidative calcination to obtain the perovskite precursor material.

[0014] In this invention, the A source is a water-soluble salt of metal A, such as at least one of metal A nitrate, metal alkoxide, chloride, and acetate.

[0015] In this invention, the metal A can be any alkaline earth metal or rare earth metal element, for example, it can be Sr.

[0016] In this invention, A represents a defect that contributes to the synergistic effect with the subsequent calcination temperature under a hydrogen-containing atmosphere. In this invention, x is preferably 0.9–0.95, more preferably 0.9–0.92.

[0017] The B source is a water-soluble salt of metal B, preferably at least one of metal B nitrate, metal alkoxide, chloride, and acetate.

[0018] Preferably, in the B metal element, the molar ratio of Co, Fe and Ni is x:y:(1-xy), where x is 0.45-0.55 and y is 0.3-0.4 (preferably 0.35-0.4);

[0019] Preferably, the perovskite substrate has the chemical formula Sr 0.9 Co x Fe y Ni 1-x-y O 3-δ The perovskite material, wherein x = 0.5, y = 0.3–0.4;

[0020] In this invention, the ingredients are prepared according to the stoichiometric ratio and then reacted with a complexing agent to obtain a gel.

[0021] In this invention, the complexing agent includes at least one of citric acid, oxalic acid, and stearic acid;

[0022] In this invention, the complexing agent further comprises at least one auxiliary agent selected from ethylenediaminetetraacetic acid, glucose, and tartaric acid. The amount of the auxiliary agent can be adjusted as needed; for example, its molar content in the complexing agent is less than or equal to 50 mol%, and more specifically, it can be 20–50 mol%.

[0023] In this invention, the ratio of the total molar amount of AB metals in the complexing agent can be adjusted as needed. Considering the processing cost, it can be further 1 to 5:1, or further 2 to 3:1.

[0024] In this invention, the temperature of the sol-gel reaction stage is 60–95°C, and the pH is 8–9.5.

[0025] Preferably, the temperature during the foaming and aging stage is 150–250°C, and more preferably 180–200°C.

[0026] There are no special requirements for the foaming and aging time, as long as a dry gel is formed. For example, the time can be more than 1 hour, and considering the processing efficiency, it can be further extended to 5 to 20 hours.

[0027] In this invention, the oxidation and calcination stage is carried out in an oxygen-containing atmosphere. The oxygen volume content of the oxygen-containing atmosphere is, for example, not less than 5%; considering processing costs, it can be further converted to air.

[0028] Preferably, the oxidation calcination temperature is 900–1100°C, and more preferably 950–1050°C;

[0029] In this invention, the time of the oxidation and calcination stage can be determined according to the formation of perovskite, and the time can be more than 1 hour. Considering the processing efficiency, it can be further 4 to 8 hours, or even 4 to 6 hours.

[0030] In this invention, the hydrogen-containing atmosphere is a composite gas of hydrogen and a protective gas;

[0031] Preferably, the protective gas is at least one selected from nitrogen and an inert gas. For example, the inert gas is Ar.

[0032] Preferably, in the hydrogen-containing atmosphere, the volume content of hydrogen is 5-25 vol%, more preferably 10-15 vol%.

[0033] This invention has discovered that by innovatively calcining A-defect perovskites in a hydrogen-containing atmosphere and further coordinating with temperature control, a synergistic effect can be achieved, enabling the precipitation of cobalt-iron-nickel ternary alloy nanoparticles at this temperature. This process improves the in-situ distribution of the nanoparticles and their chemical bonding with the substrate, thereby enhancing the OER activity and catalytic stability of the material.

[0034] In this invention, the flow rate of the hydrogen-containing atmosphere is 15-25 mL / min, and considering the treatment effect and cost, it can be further increased to 18-22 mL / min.

[0035] In this invention, the combined control of the calcination temperature is key to the unexpected formation of in-situ precipitated ternary alloy particles at low temperatures and the improvement of OER performance.

[0036] Preferably, the calcination temperature is 350–400°C, more preferably 350–360°C. Studies have found that under these preferred conditions, the OER performance of the prepared material can be further synergistically improved.

[0037] Preferably, the roasting time is 0.5 to 5 hours, and more preferably 1 to 2 hours.

[0038] The present invention also provides a perovskite-based composite catalyst with in-situ desolvated and supported cobalt-iron-nickel ternary alloy nanoparticles prepared by the aforementioned preparation method.

[0039] The special preparation method described in this invention can endow the prepared material with special physicochemical and structural characteristics, and the special material obtained by the preparation method has unexpected effects in OER catalysis.

[0040] In this invention, the perovskite-based composite catalyst comprises a perovskite substrate and in-situ desoluble Co-Fe-Ni ternary alloy nanoparticles (also referred to as alloy nanoparticles in this invention).

[0041] The perovskite substrate is a perovskite material with defects at site A and alloy nanoparticles precipitated from site B after dissolution. Its expression is A. 1-x B y O 3-δ Where A is an alkaline earth or rare earth metal element, B includes Co, Fe and Ni, 0.85≤x<1, 0<y<1, and δ represents the number of oxygen lattice defects;

[0042] The alloy nanoparticles are Co-Fe-Ni ternary alloy particles.

[0043] This invention provides a novel perovskite-based composite catalyst, which uses a single perovskite structure material with A-site defects as a substrate and innovatively combines it with Co-Fe-Ni ternary synergistic alloy particles that are desorbed and precipitated in situ on the surface. Based on the combined control of the substrate, ternary alloy and in-situ structure, synergy can be achieved, thereby improving the OER activity and catalytic stability of the material.

[0044] In this invention, the A-site defect characteristics of the substrate, the synergy between the Co-Fe-Ni ternary alloy and its in-situ desolvation and loading structure are key to improving its OER activity and catalytic stability.

[0045] In this invention, the Co-Fe-Ni ternary alloy nanoparticles are dispersed on the surface of a perovskite substrate. Furthermore, this study has found that the catalyst prepared by this method exhibits a unique "nested" structure between the Co-Fe-Ni ternary alloy nanoparticles and the perovskite matrix. The interaction between the nanoparticles and the perovskite is strong, making aggregation less likely and thus improving the stability of the catalyst system. Moreover, the preparation method simultaneously constructs solid defects and composite interfaces. The heterostructure interface composed of nanoparticles and perovskite effectively improves the surface electronic environment, accelerating charge transfer and mass transfer during catalysis and effectively enhancing oxygen evolution performance.

[0046] Preferably, the perovskite substrate has a blocky structure with an average size of about 0.5 to 0.7 μm, and the alloy nanoparticles have an average size of about 50 to 100 nm.

[0047] The present invention also provides an application of the perovskite-based composite catalyst as an OER catalyst; preferably, it is used as an OER catalyst for oxygen evolution by water electrolysis.

[0048] This invention has found that innovatively using the novel perovskite-based composite catalyst as an OER catalytic material can exhibit excellent OER catalytic activity and catalytic stability. Furthermore, its application in water electrolysis for oxygen evolution can achieve good preparation results.

[0049] The present invention also provides an anode catalyst for water electrolysis and oxygen evolution, comprising a current collector, an anode material composited on the current collector, wherein the anode material comprises an active material, a conductive agent, and a binder, and wherein the active material comprises the perovskite-based composite catalyst.

[0050] The anode catalyst of this invention, apart from containing the perovskite-based composite catalyst of this invention, may have other components and component structures that are well known in the industry.

[0051] The present invention also provides a water electrolysis device comprising an anode catalyst of the perovskite-based composite catalyst described in the present invention.

[0052] The water electrolysis device of the present invention, except for the perovskite-based composite catalyst described in the present invention, can use materials and structural components that are known in the industry.

[0053] Beneficial effects:

[0054] (1) The present invention also provides a method for preparing a perovskite-based composite catalyst, which is based on the combined control of single perovskite with A-site defects and calcination temperature under a hydrogen atmosphere. This can achieve synergy, and at the specified temperature, Co-Fe-Ni ternary alloy particles can be precipitated in situ, improving their precipitation distribution and bonding morphology with the substrate. Moreover, a large number of active sites and oxygen vacancies can be introduced, thus effectively improving the OER activity and stability of the prepared material.

[0055] (2): The preparation method described in this invention can prepare novel catalysts with special physicochemical and structural characteristics, and the catalysts with special structures prepared by the preparation method have excellent OER activity and catalytic stability.

[0056] (3): This invention innovatively uses the aforementioned perovskite-based composite catalyst as an OER catalyst, and further applies it to the electrolysis of water for oxygen evolution, exhibiting excellent activity and catalytic stability. For example, it exhibits excellent activity and catalytic stability at 10 mA / cm². 2 The overpotential was 280–290 mV. The modified perovskite showed no significant change in overpotential during a 10-hour chronopotential test, demonstrating good stability. Attached Figure Description

[0057] Figure 1 The images show the XRD patterns of the catalysts prepared in step 2 of Examples 1 to 4, where (a) is the X-ray diffraction pattern of the perovskite-based catalysts obtained in Examples 1, 2, 3 and 4, respectively; and (b) is the magnified X-ray diffraction pattern of the perovskite-based catalysts obtained in Examples 1, 2, 3 and 4 at 43° to 53°.

[0058] Figure 2 The XRD patterns of the catalysts finally obtained in Comparative Examples 1 to 4 are shown below. Part (a) is the X-ray diffraction pattern of the perovskite-based catalysts obtained in Comparative Examples 1, 2, 3 and 4; and part (b) is the magnified X-ray diffraction pattern of the perovskite-based catalysts obtained in Comparative Examples 1, 2, 3 and 4 at 43° to 53°.

[0059] Figure 3SEM images of the catalysts obtained in Examples 1-4 and Comparative Examples 1-4 are shown. (a) shows a SEM image of the perovskite-based composite catalyst with in-situ surface-dissolved cobalt-iron-nickel ternary alloy nanoparticles obtained in Example 1. (b) shows a SEM image of the perovskite-based composite catalyst with in-situ surface-dissolved cobalt-iron-nickel ternary alloy nanoparticles obtained in Example 2. (c) shows a SEM image of the perovskite-based composite catalyst with in-situ surface-dissolved cobalt-iron-nickel ternary alloy nanoparticles obtained in Example 3. (d) shows a SEM image of the perovskite-based composite catalyst with in-situ surface-dissolved cobalt-iron-nickel ternary alloy nanoparticles obtained in Example 4. (e) shows the Sr obtained in Comparative Example 1. 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ Scanning electron microscope (SEM) images of the perovskite precursor. (f) SEM image of the wet-impregnated cobalt-iron-nickel ternary alloy nanoparticle composite perovskite catalyst obtained in Comparative Example 2. (g) SEM image of the perovskite-based catalyst obtained in Comparative Example 3. (h) SEM image of the perovskite-based catalyst obtained in Comparative Example 4.

[0060] Figure 4 The images shown are transmission electron microscopy (TEM) images of the perovskite-based composite catalyst with in-situ surface-dissolved cobalt-iron-nickel ternary alloy nanoparticles obtained in Example 1. (a) shows a TEM image of the perovskite-based composite catalyst with in-situ surface-dissolved cobalt-iron-nickel ternary alloy nanoparticles; (b) shows a high-resolution TEM image of a designated area; (c) shows a selected area electron diffraction (SED) pattern of the perovskite matrix; and (d) shows a SED pattern of the alloy particle region.

[0061] Figure 5 The images show a high-angle annular dark field image (HAADF) and EDS elemental distribution diagrams of Sr, Co, Fe, Ni and O for the perovskite-based composite catalyst with surface in-situ desolvation of cobalt-iron-nickel ternary alloy nanoparticles obtained in Example 1.

[0062] Figure 6 The graph shows a performance comparison of the perovskite-based catalysts obtained in Examples 1, 2, 3, and 4.

[0063] Figure 7 The graph shows a performance comparison of the perovskite-based catalysts obtained in Comparative Examples 1, 2, 3, and 4.

[0064] Figure 8 The LSV curves of the perovskite-based catalysts obtained in Example 1 and Comparative Example 1 before and after 1000 CV cycles are shown. Detailed Implementation

[0065] The technical solution of the present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0066] The perovskite-based composite catalyst of the present invention utilizes a single perovskite structure precursor material with an A-defect (A... 1- x BO 3-δ It is prepared by calcination at a temperature of 340–410 °C in a hydrogen-containing atmosphere.

[0067] In this invention, the single-site perovskite precursor material is any A metal with A-site defects or a single-site perovskite material containing Co, Fe, and Ni. That is, any perovskite material satisfying A-site defects and containing Co, Fe, and Ni at the B-site can be used as a precursor material and, in conjunction with the hydrogen-containing atmosphere calcination conditions described in this application, to produce a novel OER catalyst material that in-situ precipitates ternary alloy particles of Co, Fe, and Ni.

[0068] In this invention, there are no special requirements for the metal element A. It can be an alkaline earth metal or a rare earth element. In this invention, Sr is a typical example of A.

[0069] For example, in this invention, the precursor material may be further Sr 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ Perovskite: In this invention, the perovskite precursor material can be prepared based on known methods, such as the sol-gel method.

[0070] The present invention provides a typical method for preparing a perovskite-based composite catalyst, the steps of which are as follows:

[0071] Step 1, Sr 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ Preparation of perovskite catalysts

[0072] Synthesis of perovskite catalyst Sr using the sol-gel method 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ powder, where δ represents Sr 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ The number of oxygen lattice defects in oxides.

[0073] Step two,

[0074] Sr 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ Perovskite powder is placed in a tube furnace and calcined in a reducing atmosphere at a temperature of 340–410°C to obtain modified perovskite.

[0075] In step one, the perovskite catalyst Sr is synthesized using the sol-gel method. 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ The oxide powder is prepared by the following steps: A certain amount of metal nitrates of strontium, cobalt, iron, and nickel are dissolved in deionized water according to the stoichiometric ratio in the chemical formulas to obtain an aqueous solution of metal salt ions. The solution is stirred at a constant temperature of 60–70°C using a magnetic stirrer. Then, a complexing agent prepared by mixing ethylenediaminetetraacetic acid and citric acid is added to the solution. Next, ammonia water is slowly added dropwise to adjust the pH of the solution to 8–9. The temperature is then increased to 80–90°C and stirred until the mixture becomes a reddish-brown gel. The resulting gel is transferred to an oven at 150–250°C and dried overnight until it becomes a black, sponge-like, porous, and loose solid. The resulting solid is ground into a uniform, fine powder in a mortar and then calcined in a muffle furnace to obtain Sr. 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ Perovskite catalyst powder.

[0076] In step one, the metal nitrates of strontium, cobalt, iron, and nickel are Sr(NO3)2, Co(NO3)2·6H2O, Fe(NO3)3·9H2O, and Ni(NO3)2·6H2O, respectively, and can be prepared according to the stoichiometric ratios described above. For example, the molar ratio of Sr, Co, Fe, and Ni is 0.9:0.5:0.35:0.15. In this invention, the total amount of elements can be adjusted according to the preparation scale. For example, the following case represents a laboratory scale, where the total number of metal ions can be 0.01–0.1 mol, and more specifically, 0.02 mol.

[0077] In step one, the molar ratio of metal ions in the solution to ethylenediaminetetraacetic acid to citric acid monohydrate is 1:1~2:1~2, and the amount of ethylenediaminetetraacetic acid added is 0.02 mol.

[0078] In step one, the roasting process is as follows: the roasting heating rate is 2-5℃ / min; the roasting temperature is 900-1000℃; the roasting time is 4-5 hours; and the cooling rate is 2-5℃ / min.

[0079] In step two, the reducing atmosphere during the calcination process is 10–15 vol% H2 / Ar.

[0080] In step two, the calcination process is as follows: the heating rate is 1-10℃ / min; the thermal reduction temperature is 350-400℃; the reduction time is 1-2 hours; and the cooling rate is 1-10℃ / min.

[0081] The preparation method described in this invention can precipitate Co-Fe-Ni ternary alloy particles in situ at the specified temperature. For example, the material obtained by the typical preparation method described above includes Sr... 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ The substrate formed by in-situ desolvation at the B site in perovskite and the Co-Fe-Ni ternary alloy nanoparticles dispersed on the substrate surface. The composition of the ternary alloy nanoparticles is CoFeNi, and δ represents Sr. 0.9 Co 0.5 Fe 0.5-x Ni x O 3-δ The number of oxygen lattice defects in oxides (not a human-controlled factor).

[0082] The process described in this invention prepares a composite catalyst material suitable for OER reactions. Electrochemical performance testing shows that the composite catalyst prepared by the in-situ desolvation method in this invention exposes more active sites through spontaneous lattice distortion, which can significantly reduce the overpotential required for electrochemical water splitting to produce hydrogen, thereby reducing the energy consumption of water splitting. This effectively achieves the advantages of low cost, simple process, high catalytic activity, and high stability.

[0083] The perovskite-based composite catalyst, prepared by the above steps using in-situ surface-desoluble cobalt-iron-nickel ternary alloy nanoparticles, was tested at 10 mA / cm². 2 The overpotential was 280–290 mV. The modified perovskite showed no significant change in overpotential during a 10-hour chronopotential test, demonstrating good stability.

[0084] In the following examples, the overnight stay refers to 6 to 12 hours.

[0085] Example 1

[0086] A method for preparing a perovskite-based composite catalyst using cobalt-iron-nickel ternary alloy nanoparticles with in-situ surface desolvation, comprising the following steps:

[0087] Step 1: Sr 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ Preparation of (precursor):

[0088] (1) According to the stoichiometric ratio in the chemical formula (the molar ratio of Sr:Co:Fe:Ni is 0.9:0.5:0.35:0.15), 0.02 mol of Sr(NO3)2, Co(NO3)2·6H2O, Fe(NO3)3·9H2O and Ni(NO3)2·6H2O were dissolved in 100 mL of deionized water to obtain an aqueous solution of metal salt ions. The solution was stirred at a constant temperature of 60-70 °C in a magnetic stirrer. Subsequently, 0.02 mol of ethylenediaminetetraacetic acid and 0.03 mol of citric acid were mixed to prepare a complexing agent and added to the solution.

[0089] (2) In the solution obtained in (1), ammonia water is slowly added dropwise using a dropper to adjust the pH value of the solution to 8-9. The temperature is then raised to 80-90℃ and heated and stirred until the mixture turns into a reddish-brown gel. The resulting gel is then transferred to an oven at 180-200℃ and dried overnight until it turns into a black, sponge-like, porous, and loose solid.

[0090] (3) The solid obtained in (2) is ground into a uniform and fine powder in a mortar, and then transferred to a muffle furnace for calcination. The temperature is increased to 1000℃ at a rate of 2℃ / min and held for 5 hours. After cooling, it is removed and ground again to obtain Sr with good crystallinity. 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ Perovskite catalyst powder.

[0091] Step 2:

[0092] The Sr prepared by the method described in 1 was subjected to in-situ exsolution. 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ Modification of perovskite powder: Sr 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ Perovskite powder was placed in a tube furnace and calcined at 350°C (marked as T) for 1 hour in a 10% H2 / Ar atmosphere with a gas flow rate of 20 mL / min to obtain a perovskite-based composite catalyst with in-situ desolvated cobalt-iron-nickel ternary alloy nanoparticles.

[0093] Example 2

[0094] Compared with Example 1, the only difference is that the temperature of T in step 2 is 400°C, and the other operations and parameters are the same as in Example 1.

[0095] Example 3

[0096] Compared to Example 1, the only difference is that the proportion of element A is changed, and the chemical formula of the designed precursor is Sr. 0.95 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ Other operations and parameters are the same as in Example 1.

[0097] Example 4

[0098] Compared to Example 1, the only difference is that the proportion of elements in B is changed, and the chemical formula of the designed precursor is Sr. 0.9 Co 0.5 Fe 0.4 Ni 0.1 O 3-δ Other operations and parameters are the same as in Example 1.

[0099] Comparative Example 1

[0100] Compared to Example 1, the only difference is that the hydrogen roasting treatment in step 2 was not performed. All other operations and parameters are the same as in Example 1, i.e., the Sr prepared in step 1 is used. 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ Perovskite catalysts are used as OER catalysts.

[0101] Comparative Example 2

[0102] A method for preparing a cobalt-iron-nickel ternary alloy nanoparticle composite perovskite catalyst, using a wet impregnation method, comprises the following steps:

[0103] 1. Dissolve 1 mmol of Co(NO3)2·6H2O, Fe(NO3)3·9H2O, and Ni(NO3)2·6H2O in 10 mL of deionized water, respectively, and then add 10 mmol of SCFN powder (Sr prepared in step 1 of Example 1). 0.9 Co 0.5 Fe 0.35 Ni 0.15 O 3-δ (Precursor).

[0104] 2. After stirring on a magnetic stirrer for 24 hours at room temperature, place the sample in a vacuum drying oven to dry.

[0105] 3. Finally, the catalyst was calcined at 600°C for 1 hour in air to obtain the catalyst.

[0106] Comparative Example 3 - The precursor is a non-A defect material

[0107] Compared to Example 1, the only difference is that the material without A-site defects, i.e., the chemical formula of the designed precursor is SrCo. 0.5 Fe 0.35 Ni 0.15 O 3-δ Other operations and parameters are the same as in Example 1.

[0108] Comparative Example 4

[0109] Compared with Example 1, the only difference is that the temperature of T in step 2 is 300°C, and the other operations and parameters are the same as in Example 1.

[0110] Figure 1 (ad) in the figures represent the X-ray diffraction patterns of the perovskite-based catalysts prepared in Examples 1-4, respectively. The patterns reveal that, after calcination, a pure perovskite phase material containing the CoFeNi alloy phase was obtained.

[0111] To test the oxygen evolution catalytic performance of the catalyst prepared by the above-mentioned method of preparing perovskite-based composite catalyst with cobalt-iron-nickel ternary alloy nanoparticles with in-situ surface desolvation, the following test example was set up.

[0112] The testing steps are as follows:

[0113] 1. Preparation of test ink: For each of the eight samples from Examples 1-4 and Comparative Examples 1-4, 5 mg of catalyst sample and 5 mg of Super P Li were weighed and dispersed in 1 mL of anhydrous ethanol, and mixed thoroughly. Separately, 50 μL of Nafion solution was added dropwise to the aforementioned ethanol-based mixture, and the mixture was ultrasonically vibrated for 1.5 h to form a homogeneous catalyst ink.

[0114] 2. Take 10 μL of the catalyst ink from the above 8 samples and coat it onto a polished surface with an area of ​​0.196 cm². 2 The glassy carbon electrode center was air-dried to form a uniform black film, thus obtaining the working electrode. The working electrode was then transferred to the electrolyte for electrochemical measurements; the catalyst loading was 0.243 mg / cm³. -2 .

[0115] 3. The electrochemical performance of the catalyst was measured at room temperature using a conventional three-electrode system. A glassy carbon electrode modified with catalyst ink was used as the working electrode, an Hg / HgO (1.0 M KOH) electrode as the reference electrode, and a platinum sheet electrode as the counter electrode. The electrolyte was an O2-saturated 1.0 M KOH solution. Linear sweep voltammetry was performed within a potential window of 0.2–1.0 V at a scan rate of 5 mV / s. -1 The comparison current density is 10 mA / cm². 2 The corresponding overpotential. Accelerated durability testing is performed at 100 mV / s. -1 The scan rate was CV-cycled 1000 times within a voltage range of 0.2 to 1.0 V, and then a linear scan voltammetry test was performed again to compare the changes in overpotential before and after the cycle.

[0116] Table 1. Overpotential test results of the samples obtained in Examples 1-4 and Comparative Examples 1-4 as oxygen evolution catalysts.

[0117]

[0118] like Figure 1 and Figure 2 As shown, all catalysts exhibited a cubic perovskite structure containing the Pm-3m space group. After reduction for 1 h in a 10% H2 / Ar atmosphere at 340–410 °C (preferably 350–400 °C), the characteristic peaks of the perovskite shifted to lower angles, indicating lattice expansion. This may be due to the regulation of oxygen vacancies or lattice distortion after SCFN desolvation. Furthermore, two new peaks appeared at ~45° and ~52° in the XRD patterns of Examples 1, 2, 3, 4, and Comparative Example 2. This can be attributed to the presence of the CoFeNi alloy, confirming the desolvation of the metal nanoparticles after thermal reduction. No new peaks were found in the XRD patterns of Comparative Example 3 and Comparative Example 4, indicating that the preparation conditions could not achieve in-situ desolvation of the nanoalloy particles.

[0119] like Figure 3 As shown, the perovskite-based composite catalysts obtained in Examples 1, 2, 3, and 4 have a large number of spherical nanoparticles uniformly dispersed on their surface, while the surface of Example 1 is smooth. This indicates that the preparation method of the present invention can desorb a large number of nanoparticles from the perovskite matrix. In Comparative Example 2, some irregular lumps of varying sizes appear on the surface, with clear boundaries from the perovskite matrix, indicating that the interaction between the two phases in the composite material prepared by the wet impregnation method is not as strong as that prepared by the desorption method. In Comparative Examples 3 and 4, no nanoparticles are distributed on the surface, indicating that a perovskite-based composite catalyst with a surface-dispersed nano-alloy particle distribution cannot be obtained under these preparation conditions.

[0120] like Figure 4As shown in the transmission electron microscope (TEM) image of the perovskite-based composite catalyst with in-situ surface-desoluble cobalt-iron-nickel ternary alloy nanoparticles obtained in Example 1, it can be seen that the perovskite-based composite catalyst with in-situ surface-desoluble cobalt-iron-nickel ternary alloy nanoparticles was successfully prepared.

[0121] like Figure 5 As shown, the high-angle annular dark field image (HAADF) and EDS elemental distribution maps of Sr, Co, Fe, Ni and O of the perovskite-based composite catalyst with surface in-situ desolvation of cobalt-iron-nickel ternary alloy nanoparticles obtained in Example 1 are shown. High concentrations of Co, Fe and Ni aggregation regions can be clearly observed in the figure, and no other elements are distributed in this region, indicating the precipitation of cobalt-iron-nickel ternary alloy nanoparticles.

[0122] like Figure 6 As shown in the figure, and referring to Table 1, it can be concluded that at a current density of 10 mA / cm²... 2 In comparison, the overpotentials of Examples 1, 2, 3, and 4 were all lower than those of Comparative Examples 1, 2, 3, and 4, indicating that the perovskite-based composite catalyst with in-situ surface-dissolved cobalt-iron-nickel ternary alloy nanoparticles exhibits superior oxygen evolution reaction (OER) catalytic performance with significant advantages. Furthermore, Examples 1, 2, 3, and 4 all possessed smaller Tafel slope values, indicating that the perovskite-based composite catalyst with in-situ surface-dissolved cobalt-iron-nickel ternary alloy nanoparticles exhibits good OER reaction kinetics. After 1000 CV cycles, the overpotential changes of Examples 1, 2, 3, and 4 were all smaller than those of Comparative Examples 1, 2, 3, and 4, indicating that the perovskite-based composite catalyst with in-situ surface-dissolved cobalt-iron-nickel ternary alloy nanoparticles exhibits good cycling stability. The product obtained by the method for preparing the perovskite-based composite catalyst with in-situ surface-dissolved cobalt-iron-nickel ternary alloy nanoparticles disclosed in this invention has good commercial value as an electrocatalyst for the OER reaction in water electrolysis.

[0123] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a perovskite-based composite catalyst with cobalt-iron-nickel ternary alloy nanoparticles supported by surface in-situ solvent removal, characterized in that, The chemical formula for obtaining Sr site defects is Sr 0.9 Co x Fe y Ni 1-x-y O 3-δ The perovskite precursor material is then calcined in a hydrogen-containing atmosphere at a temperature of 350~360℃ to obtain the product. Sr 0.9 Co x Fe y Ni 1-x-y O 3-δ In it, x = 0.5, y = 0.3 to 0.

4.

2. The preparation method according to claim 1, characterized in that, The perovskite precursor material is prepared by the sol-gel method, and the steps are as follows: stoichiometric amounts of source A, source B and complexing agent are mixed and subjected to sol-gel reaction, followed by foaming and aging to obtain dry gel, and then oxidative calcination treatment to obtain the perovskite precursor material. Source A is a water-soluble salt of metal A; metal A is Sr; The source of B is a water-soluble salt of metal B; metal B is Co, Fe, and Ni.

3. The preparation method according to claim 2, characterized in that, The complexing agent includes at least one of citric acid, oxalic acid, and stearic acid; The ratio of the complexing agent to the total metal molar amount of AB is 1~5:

1.

4. The preparation method according to claim 3, characterized in that, Source A is at least one of the following: nitrate, sulfate, chloride, and acetate of metal A; The source of B is at least one of the following: nitrate, metal alkoxide, chloride, and acetate of metal B; The ratio of the complexing agent to the total metal molar amount of AB is 2~3:1; The complexing agent also includes at least one of ethylenediaminetetraacetic acid, glucose, and tartaric acid.

5. The preparation method according to claim 3, characterized in that, The temperature during the sol-gel reaction stage is 60~95℃, and the pH is 8~9.5; The temperature during the foaming and aging stage is 150~250℃; The oxidation and calcination stage is carried out in an oxygen-containing atmosphere; The oxygen volume content of the oxygen-containing atmosphere is not less than 5%; The oxidation calcination temperature is 900~1100 ℃; The oxidation and calcination stage lasts for 4 to 8 hours.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The hydrogen-containing atmosphere is a composite gas of hydrogen and a protective gas; The protective gas is at least one of nitrogen and an inert gas; In the hydrogen-containing atmosphere, the volume content of hydrogen is 5-25% (v%). The flow rate of the hydrogen-containing atmosphere is 15~25 mL / min; The roasting time is 0.5 to 5 hours.

7. The preparation method according to claim 6, characterized in that, In the hydrogen-containing atmosphere, the volume content of hydrogen is 10-15% (v%). The roasting time is 1 to 2 hours.

8. A perovskite-based composite catalyst with surface in-situ dissolved and supported cobalt-iron-nickel ternary alloy nanoparticles, prepared by the preparation method according to any one of claims 1 to 7, characterized in that, It includes the perovskite substrate formed by in-situ desolvation in perovskite precursor materials and the Co-Fe-Ni ternary alloy nanoparticles in-situ composite on the surface of the perovskite substrate.

9. The perovskite-based composite catalyst with surface in-situ desolvation and supported cobalt-iron-nickel ternary alloy nanoparticles as described in claim 8, characterized in that, The Co-Fe-Ni ternary alloy nanoparticles are dispersed on the surface of the perovskite substrate; The perovskite substrate has a blocky structure with an average size of 0.5~0.7 μm, and the Co-Fe-Ni ternary alloy nanoparticles have an average particle size of 50~100 nm.

10. The application of a perovskite-based composite catalyst with surface in-situ dissolved and supported cobalt-iron-nickel ternary alloy nanoparticles prepared by the preparation method according to any one of claims 1 to 7, characterized in that, It was used as an OER catalyst.

11. The application as described in claim 10, characterized in that, It was used as an OER catalyst for oxygen evolution in water electrolysis.

12. An anode catalyst for water electrolysis and oxygen evolution, characterized in that, The active material includes a perovskite-based composite catalyst with surface in-situ desolvation and loading of cobalt-iron-nickel ternary alloy nanoparticles prepared by the preparation method according to any one of claims 1 to 7.

13. A water electrolysis device, characterized in that, It comprises the anode catalyst as described in claim 12.

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