In-situ heterogeneous nucleation supported catalyst as well as preparation method and application thereof

Abstract

The invention discloses an in-situ heterogeneous nucleation supported catalyst as well as a preparation method and application thereof. The method comprises the following steps: firstly, precipitating a conductive metal oxide carrier precursor at a low pH value of 6.0-10; a solution containing two or more metal cations of nickel, iron, cobalt, chromium, manganese, copper and zinc is precipitated on the surface of the carrier under the condition that the pH is equal to 10-14, and high-dispersion transition metal-based active nanoparticles are formed on the carrier through in-situ heterogeneous nucleation; and finally, aging, washing, drying and carrying out heat treatment to obtain the catalyst. According to the method, a particle-carrier structure with uniformly loaded active particles and a clear interface is successfully constructed through fractional precipitation and interface nucleation control, a solid solution formed by traditional coprecipitation is effectively avoided, and maximum exposure and strong interface bonding of active sites are realized. The prepared catalyst shows high activity, low overpotential and excellent long-term operation stability in water electrolysis oxygen evolution reaction, and is simple in process, good in reproducibility and suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the fields of electrocatalytic materials and new energy technology, specifically to a supported catalyst for in-situ heterogeneous nucleation, its preparation method, and its application. Background Technology

[0002] Electrolysis of water to produce hydrogen is a green hydrogen production technology; however, the oxygen evolution reaction kinetics at the anode are sluggish, requiring a highly efficient catalyst to reduce overpotential. Currently, iridium and ruthenium oxides are commercially available standard raw materials, but their high cost and scarcity limit their large-scale application.

[0003] Non-precious metal materials such as nickel-iron-based, cobalt-manganese-based, and copper-zinc-based materials are promising alternatives, but their performance is still limited by the number, stability, and conductivity of active sites. Traditional methods, such as impregnation, struggle to achieve high dispersion and strong interfacial bonding of active components; while conventional co-precipitation methods easily form solid solutions or composite oxides where the active metal and carrier components are atomically homogeneous. This homogeneous structure may result in the burial of some active sites, suboptimal electron transport paths, and under long-term high-pressure operation, component segregation, particle sintering, or dissolution can easily occur, leading to deactivation.

[0004] Therefore, there is an urgent need for a new preparation method that can precisely construct highly exposed and stable active centers at the nanoscale and enable them to achieve strong electronic coupling with conductive substrates. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing technologies and provide an in-situ heterogeneous nucleation supported catalyst, its preparation method, and its application. This method involves first forming a support matrix, and then inducing in-situ heterogeneous nucleation and growth of active components on its surface, thereby creating a composite catalytic material with a clear interface, strong bonding, and highly dispersed active sites.

[0006] In one aspect of the present invention, a method for preparing an in-situ heterogeneous nucleation supported catalyst is provided. According to an embodiment of the present invention, the method includes the following steps:

[0007] S1, containing the first metal cation M n+ The first salt solution is mixed with the first precipitant to carry out the first precipitation reaction. The pH value of the reaction system is controlled to be 6.0-10 to generate a precursor slurry of conductive metal oxide, wherein M is selected from at least one of Cr, Mo, W and Sn.

[0008] S2. Without separating the precursor slurry, a second salt solution and a second precipitant are added to it to carry out a second precipitation reaction. The pH value of the reaction system is controlled to be 10-14, and the pH value of the second reaction is higher than that of the first reaction. The second salt solution contains at least two metal cations selected from nickel, iron, cobalt, chromium, manganese, copper and zinc.

[0009] S3. The product after the second step reaction is aged, separated into solid and liquid phases, washed, dried, and heat-treated to obtain the catalyst. The aging process is controlled at a temperature of 40-80℃ for 6-24 hours; solid-liquid separation is performed by centrifugation at 3000-8000 rpm for 2-15 minutes, with 3-6 centrifugation cycles; washing includes repeated washing of the precipitate with deionized water until the filtrate is neutral, followed by washing with anhydrous ethanol 1-5 times; drying is performed under vacuum at 40-90℃ for 6-24 hours.

[0010] This invention is based on the principles of stepwise precipitation and solubility product difference, achieving stepwise construction of the carrier and active components through precise control of the pH gradient. Step S1 controls the pH between 6.0 and 10, utilizing Cr... 3+ Mo n+ Under these weakly alkaline conditions, the carrier metal ions can be hydrolyzed to form hydroxides or hydrated oxide precursors (such as Cr(OH)3, WO3·xH2O), while Ni... 2+ Fe 3+ The active metal ions remain dissolved due to their high solubility product, thus pre-constructing a complete conductive metal oxide support matrix and preventing premature co-precipitation of the active components. In step S2, the pH is raised to 10⁻¹⁴ and ensured to be significantly higher than in the first step. At this point, the supersaturation of the active metal ions exceeds the precipitation threshold. Based on the thermodynamic priority principle of heterogeneous nucleation, homogeneous nucleation preferentially occurs on the surface of the already formed support precursor rather than in solution. The reaction pathway is M. 2+ / 3+ Hydroxide / carbonate nanoparticles are generated in situ at the solid-liquid interface. High dispersibility is ensured by controlling the dropping rate (0.1-5.0 mL / min), which ultimately achieves precise positioning and maximum exposure of active sites on the carrier surface, completely avoiding the embedding problem caused by homogeneous structure.

[0011] Subsequent heat treatment is based on the principles of thermal decomposition and lattice reconstruction. The precursor is dehydrated and crystallized to form a stable oxide phase through oxidation calcination at 100-600℃. Then, oxygen vacancies and metal valence states are regulated by reduction treatment at 200-500℃. The aging process relies on Ostwald ripening to promote grain perfection and interface bonding. Combined with washing and drying, impurities are removed and agglomeration is prevented. Finally, a supported catalyst with clear interface, strong bonding, high activity and long-term stability is obtained.

[0012] In addition, the method for preparing an in-situ heterogeneous nucleation supported catalyst according to the above embodiments of the present invention may also have the following additional technical features:

[0013] In some embodiments of the present invention, the reaction temperature of steps S1 and S2 is 30-90°C; in step S2, the dropping rate of the second salt solution is 0.1-5.0 mL / min.

[0014] In some embodiments of the present invention, the first precipitant and the second precipitant are one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonia, and ammonium carbonate.

[0015] In some embodiments of the present invention, step S3 includes the following heat treatment: calcination in air or an inert atmosphere at 100-600°C for 1-20 hours, followed by treatment in a reducing or inert atmosphere at 200-500°C for 0.5-3 hours. The first heat treatment is based on the principle of thermal decomposition-oxidation crystallization, which dehydrates and decarbonizes the hydroxide / carbonate precursor and oxidizes and crystallizes it to form a stable oxide lattice framework, avoiding lattice defects caused by direct reduction. The second heat treatment is based on the principle of controllable reduction-oxygen vacancy regulation, which, while protecting the integrity of the lattice, reduces surface metal ions to a specific valence state or introduces oxygen vacancies to optimize electron transport and catalytic activity.

[0016] In another aspect of the present invention, the present invention proposes an in-situ heterogeneous nucleation supported catalyst prepared by the aforementioned preparation method.

[0017] In addition, the supported catalyst for in-situ heterogeneous nucleation according to the above embodiments of the present invention may also have the following additional technical features:

[0018] In some embodiments of the present invention, a conductive metal oxide carrier and transition metal-based nanoparticles uniformly loaded on its surface are included.

[0019] In some embodiments of the present invention, the conductive metal oxide support is Cr2O3 or MoO. x WO x The active particles contain at least one of the following: Ni, Fe, Co, Mn, Cu, and Zn, where x is a stoichiometric value.

[0020] In another aspect of the invention, an electrode is proposed. According to an embodiment of the invention, it comprises a conductive substrate and the aforementioned in-situ heterogeneous nucleation supported catalyst loaded on the conductive substrate.

[0021] In another aspect of the invention, an electrolytic water anode is provided. An embodiment of the invention includes the aforementioned electrode.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. This invention employs an in-situ heterogeneous nucleation strategy. By pre-precipitating and constructing a crystal-rich carrier precursor slurry at low pH and maintaining its non-separation, heterogeneous nucleation is induced at high pH using the difference in solubility product. This forces the nucleation reaction of the active components to be confined to the interface of the pre-constructed carrier, effectively avoiding homogeneous co-precipitation and directionally guiding the formation of a heterogeneous structure of "particles loaded on the carrier," thus ensuring the maximum exposure and full utilization of active sites.

[0024] 2. The structure of the catalyst of this invention combines the high activity of ultrafine nanoparticles with the stable anchoring and rapid electron transport advantages of conductive supports, enabling the catalyst to simultaneously possess low overpotential, high conversion frequency and ultra-long operating life.

[0025] 3. The in-situ heterogeneous nucleation method of the present invention has high versatility. It is applicable not only to a variety of conductive metal oxide supports, but also to a variety of active metal combinations (such as NiFe, CoMn, CuZn, etc.). The catalyst composition can be rationally designed according to specific reaction requirements.

[0026] 4. The process of this invention can precisely control the particle size and loading by adjusting parameters such as pH, temperature, and concentration. It is applicable to a variety of carriers, has good repeatability, and is easy to scale up.

[0027] 5. This invention utilizes the strong interfacial anchoring formed by in-situ heterogeneous nucleation and the carrier confinement effect to stabilize and anchor the active particles, effectively inhibiting their sintering, agglomeration, and dissolution loss. At the same time, it avoids phase segregation of homogeneous solid solutions, ensuring the structural integrity and ultra-long lifespan of the catalyst under long-term high-pressure operation.

[0028] 6. This invention forms a strong interfacial bond between active particles and the support through an in-situ heterogeneous nucleation mechanism, allowing active metals (Ni, Fe, etc.) to nucleate and grow on the support surface, rather than existing in the form of physical mixture or solid solution. This structure effectively inhibits the segregation, migration and aggregation of components during long-term operation. At the same time, the "stabilizing anchoring" effect of the conductive support on the active particles prevents the sintering growth and dissolution loss of nanoparticles under high temperature and high pressure conditions. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some implementation examples of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The X-ray diffraction (XRD) spectra of the in-situ heterogeneous nucleation supported catalyst prepared in Example 1 of the present invention and the catalyst material prepared in Comparative Example 1 are shown.

[0031] Figure 2 Linear sweep voltammetry (LSV) curve of the in-situ heterogeneous nucleation supported catalyst prepared in Example 1 of this invention;

[0032] Figure 3 The in-situ heterogeneous nucleation supported catalyst prepared in Example 1 of this invention was used at 0.5 Å cm⁻¹. -2 Stability performance diagram under current density conditions;

[0033] Figure 4 Transmission electron microscopy (TEM) image of the in-situ heterogeneous nucleation supported catalyst prepared in Example 1 of this invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] A method for preparing an in-situ heterogeneous nucleation supported catalyst includes the following steps:

[0037] (1) Dissolve 2 mmol Cr(NO3)3·9H2O in 40 mL of deionized water to obtain solution A. Dissolve 0.8 mmol Ni(NO3)2·6H2O and 0.2 mmol Fe(NO3)3·9H2O in 20 mL of water to obtain solution B. Prepare a mixed alkaline solution C of 1.0 M NaOH and 0.5 M Na2CO3.

[0038] (2) At 60°C, solution A and mixed alkaline solution C were added dropwise into 30 mL of hot water while stirring. The pH was maintained at 9.5. After the addition was complete, the mixture was stirred for 30 minutes to obtain a gray-blue slurry.

[0039] (3) Maintaining the conditions, mix alkaline solution B and mix alkaline solution C are dripped into the above slurry in a parallel flow, maintaining pH=10.5, so that Ni 2+ and Fe 3+ In-situ heterogeneous nucleation occurs on the carrier surface. After dripping, it is aged at 70°C for 18 hours.

[0040] (4) The product is centrifuged, washed with water and alcohol, and then vacuum dried at 60°C.

[0041] (5) The product obtained in step (4) was calcined at 350°C for 2 hours in air atmosphere, and then reduced at 500°C for 1 hour in 5% H2 / Ar atmosphere to obtain black powder NiFe / Cr2O3.

[0042] Linear sweep voltammetry (LSV) was performed on the in-situ heterogeneous nucleation supported catalyst prepared in Example 1 using an electrochemical workstation with a three-electrode system. The LSV was conducted on a nickel foam electrode coated with the in-situ heterogeneous nucleation supported catalyst, with an Ag / AgCl electrode as the reference electrode and a platinum wire as the counter electrode. The in-situ heterogeneous nucleation supported catalyst material was dispersed in isopropanol, deionized water, and 5% Nafion, and then ultrasonically treated to form a uniform ink to prepare the catalyst ink. The prepared ink was sprayed onto the surface of the nickel foam electrode; LSV was then performed at 25°C using a 1.0 MkOH solution. The results are as follows: Figure 2 As shown, the linear sweep voltammetry (LSV) curve of the in-situ heterogeneous nucleation supported catalyst prepared in Example 1 shows that the catalyst exhibits good performance at 10 mA cm⁻¹. -2 The overpotential at current density is 292mV, and at 100mA cm⁻¹ -2 The overpotential at the current density is 392mV.

[0043] The in-situ heterogeneous nucleation supported catalyst material prepared in Example 1 was studied using an electrochemical workstation in a three-electrode system at 100 mA cm⁻¹. -2 Stability tests were conducted at various current densities. The stability tests were performed on an electrochemical workstation using a three-electrode system. Nickel foam with an in-situ heterogeneous nucleated supported catalyst was used as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum wire as the counter electrode. The tests were conducted at 25°C using 1.0 M KOH solution. The results are as follows: Figure 3 As shown, the in-situ heterogeneous nucleation supported catalyst prepared according to Example 1 was used in a 0.5 Å cm⁻¹ hydrothermal ionization process. -2 Stability tests were conducted at current density, and after 42 hours of operation, the voltage drop rate was 0.5 mV / h.

[0044] The microstructure of the in-situ heterogeneous nucleation supported catalyst prepared in Example 1 was characterized using transmission electron microscopy. The experimental procedure included: sonicating the sample in ethanol, taking a drop of the supernatant liquid onto a support mesh, and allowing it to dry naturally before testing. The results are as follows: Figure 4 As shown in the transmission electron microscope (TEM) image of the in-situ heterogeneous nucleation supported catalyst prepared in Example 1, it can be seen that NiFe nanoparticles are highly dispersed on the Cr2O3 support.

[0045] Example 2

[0046] A method for preparing an in-situ heterogeneous nucleation supported catalyst includes the following steps:

[0047] (1) Dissolve 2 mmol Cr(NO3)3·9H2O in 40 mL of deionized water to obtain solution A. Prepare five different solutions B, in which the total amount of Ni(NO3)2 is fixed at 0.8 mmol, and the amounts of Fe(NO3)3 are 0, 0.1, 0.2, 0.4, and 0.8 mmol, respectively, with corresponding Fe / Ni molar ratios of 0, 0.125, 0.25, 0.5, and 1.0. Prepare a mixed alkaline solution C of 1.0 M NaOH and 0.5 M Na2CO3.

[0048] (2) At 60°C, solution A and mixed alkaline solution C were added dropwise into 30 mL of hot water while stirring. The pH was maintained at 9.5. After the addition was complete, the mixture was stirred for 30 minutes to obtain a gray-blue slurry.

[0049] (3) Maintaining the conditions, solution B and mixed alkaline solution C are dripped into the above slurry in a parallel flow, maintaining pH=10.5, so that Ni 2+ and Fe 3 + In-situ heterogeneous nucleation occurs on the carrier surface. After dripping, it is aged at 70°C for 18 hours.

[0050] (4) The product is centrifuged, washed with water and alcohol, and then vacuum dried at 60°C.

[0051] (5) The product obtained in step (4) is calcined at 350°C for 2 hours in air atmosphere, and then reduced at 500°C for 1 hour in 5% H2 / Ar atmosphere to obtain black powder NiFe(X) / Cr2O3, where X is the Fe / Ni molar ratio.

[0052] Example 3

[0053] A method for preparing an in-situ heterogeneous nucleation supported catalyst includes the following steps:

[0054] (2) Dissolve 2 mmol Cr(NO3)3·9H2O in 40 mL of deionized water to obtain solution A. Dissolve 0.8 mmol Co(NO3)2·6H2O and 0.2 mmol Mn(NO3)3·4H2O in 20 mL of water to obtain solution B. Prepare a mixed alkaline solution C of 1.0 M NaOH and 0.5 M Na2CO3.

[0055] (2) At 60°C, solution A and alkali solution C were added dropwise into 30 mL of hot water while stirring. The pH was maintained at 9.5. After the addition was complete, the mixture was stirred for 30 minutes to obtain a gray-blue slurry.

[0056] (3) Maintaining the conditions, solution B and alkali solution C are dripped into the above slurry in a parallel flow, maintaining pH=10.5, so that Ni2+ and Fe 3+ In-situ heterogeneous nucleation occurs on the carrier surface. After dripping, it is aged at 70°C for 18 hours.

[0057] (4) The product is centrifuged, washed with water and alcohol, and then vacuum dried at 60°C.

[0058] (5) The product obtained in step (4) was calcined at 350°C for 2 hours in air atmosphere, and then reduced at 500°C for 1 hour in 5% H2 / Ar atmosphere to obtain black powder CoMn / Cr2O3.

[0059] Example 4

[0060] A method for preparing an in-situ heterogeneous nucleation supported catalyst includes the following steps:

[0061] (1) Dissolve 2 mmol Cr(NO3)3·9H2O in 40 mL of deionized water to obtain solution A. Dissolve 0.5 mmol Co(NO3)2·6H2O, 0.3 mmol Cu(NO3)2·3H2O and 0.2 mmol Mn(NO3)2·4H2O in 20 mL of water to obtain ternary active salt solution B. Prepare a mixed alkaline solution C of 1.0 M NaOH and 0.5 M Na2CO3.

[0062] (2) At 60°C, solution A and alkali solution C were added dropwise into 30 mL of hot water while stirring. The pH was maintained at 9.5. After the addition was complete, the mixture was stirred for 30 minutes to obtain a gray-blue slurry.

[0063] (3) Maintaining the conditions, solution B and alkali solution C are dripped into the above slurry in a parallel flow, maintaining pH=10.5, so that Ni 2+ and Fe 3+ In-situ heterogeneous nucleation occurs on the carrier surface. After dripping, it is aged at 70°C for 18 hours.

[0064] (4) The product is centrifuged, washed with water and alcohol, and then vacuum dried at 60°C.

[0065] (5) The product obtained in step (4) was calcined at 350°C for 2 hours in air atmosphere, and then reduced at 500°C for 1 hour in 5% H2 / Ar atmosphere to obtain black powder CoCuMn / Cr2O3.

[0066] Example 5

[0067] A method for preparing an in-situ heterogeneous nucleation supported catalyst includes the following steps:

[0068] (1) Dissolve 2 mmol of ammonium metatungstate in 40 mL of deionized water, and adjust the pH to about 3 with dilute nitric acid to prevent premature hydrolysis, to obtain solution A. The preparation of active component solution B (Ni and Fe salts) and mixed alkaline solution C is the same as in Example 1.

[0069] (2) Under stirring at 70°C, solution A and alkali solution C are slowly added to the reactor in parallel flow, and the pH is controlled at 4.0 (this lower pH is a suitable condition for precipitating WO3·xH2O precursor). After the addition is complete, stir for 1 hour to obtain a light yellow tungstic acid slurry.

[0070] (3) Maintain the temperature, add solution B and alkali solution C dropwise in parallel, control the total pH to 9.0, and make Ni 2+ and Fe 3+ In-situ heterogeneous nucleation occurs on the carrier surface. Subsequent aging, washing, and drying steps are the same as in Example 1.

[0071] (4) The product obtained in step (4) is calcined in air at 450°C for 3 hours to obtain NiFe / WO3 catalyst.

[0072] Example 6

[0073] A method for preparing an in-situ heterogeneous nucleation supported catalyst includes the following steps:

[0074] (1) Place 2 mmol of ammonium molybdate in 40 mL of deionized water, add dilute ammonia dropwise and stir until completely dissolved to form a clear solution, which is solution A. The active component solution B (containing 0.8 mmol Ni(NO3)2·6H2O and 0.2 mmol Fe(NO3)3·9H2O) and the mixed alkaline solution C (1.0 M NaOH + 0.5 M Na2CO3) are prepared in the same way as in Example 1.

[0075] (2) At 80°C, with stirring, solution A and alkali solution C were added dropwise to the reactor in parallel, and the pH of the first-step precipitation reaction system was controlled to be 9.0. After the addition was completed, stirring was continued for 30 minutes to obtain a slurry containing molybdenum precursor.

[0076] (3) Maintain the temperature and stirring, and drip solution B and alkali solution C into the above slurry in a parallel flow, controlling the pH value of the second step reaction system to be 10.5, so that Ni 2+ and Fe 3+ In-situ heterogeneous nucleation occurs on the carrier surface. After dripping, it is aged at 80°C for 18 hours.

[0077] (4) The product is centrifuged, washed with water and alcohol, and then vacuum dried at 60°C.

[0078] (5) The product obtained in step (4) was calcined at 400°C for 3 hours in air atmosphere, and then reduced at 450°C for 1.5 hours in 5% H2 / Ar atmosphere to obtain black powder NiFe / MoO3.

[0079] Example 7

[0080] A method for preparing an in-situ heterogeneous nucleation supported catalyst includes the following steps:

[0081] (1) Dissolve 2 mmol of stannous chloride in a small amount of concentrated hydrochloric acid, then dilute with deionized water to 40 mL and use immediately to prevent hydrolysis, as solution A. Dissolve 0.8 mmol of Ni(NO3)2·6H2O and 0.2 mmol of Fe(NO3)3·9H2O in 20 mL of water to obtain solution B. Prepare a mixed alkaline solution C of 1.0 M NaOH and 0.5 M Na2CO3.

[0082] (2) At 60°C, with stirring, add solution A and alkaline solution C dropwise in parallel, controlling the pH of the first precipitation reaction system to 4.0 (precipitate Sn(OH)4 under acidic to weakly alkaline conditions to prevent the formation of stannic acid sol). Stir for 1 hour after the addition is complete.

[0083] (3) Maintain the temperature, add solution B and alkali solution C dropwise in parallel, and control the pH of the second-step reaction system to 9.5, so that Ni 2+ and Fe 3+ In-situ heterogeneous nucleation occurs on the carrier surface. After dripping, it is aged at 60°C for 24 hours.

[0084] (4) The product is centrifuged, washed with water and alcohol, and then vacuum dried at 60°C.

[0085] (5) The product obtained in step (4) is calcined at 450°C for 3 hours in air atmosphere, and then reduced at 350°C for 2 hours in 5% H2 / Ar atmosphere to obtain black powder NiFe / SnO2.

[0086] Example 8

[0087] A method for preparing an in-situ heterogeneous nucleation supported catalyst includes the following steps:

[0088] (1) Prepare a mixed aqueous solution containing 1 mmol Cr(NO3)3 and 1 mmol SnCl4 (dissolved in dilute hydrochloric acid), with a total volume of 40 mL, as solution A. Dissolve 0.8 mmol Ni(NO3)2·6H2O and 0.2 mmol Fe(NO3)3·9H2O in 20 mL of water to obtain solution B. Prepare a mixed alkaline solution C of 1.0 M NaOH and 0.5 M Na2CO3.

[0089] (2) Under stirring at 80℃, solution A and alkali solution C were added dropwise in parallel, and the pH of the first precipitation reaction system was controlled to be 8.5, which is a compromise condition for the co-precipitation of the two metal hydroxides. After the addition was completed, the mixture was stirred for 1 hour.

[0090] (3) Maintaining the conditions, solution B and alkali solution C are dripped into the above slurry in a parallel flow, maintaining pH=10.5, so that Ni 2+ and Fe 3+ In-situ heterogeneous nucleation occurs on the carrier surface. After dripping, it is aged at 80°C for 24 hours.

[0091] (4) The product is centrifuged, washed with water and alcohol, and then vacuum dried at 60°C.

[0092] (5) The product obtained in step (4) was calcined at 450°C for 2 hours in air atmosphere, and then reduced at 400°C for 2 hours in 5% H2 / Ar atmosphere to obtain black powder NiFe / Cr2O3-SnO2.

[0093] Comparative Example 1

[0094] A method for preparing a supported catalyst includes the following steps:

[0095] (1) Dissolve 2 mmol Cr(NO3)3·9H2O in 40 mL of deionized water to obtain solution A. Dissolve 0.8 mmol Ni(NO3)2·6H2O and 0.2 mmol Fe(NO3)3·9H2O in 20 mL of water to obtain solution B. Prepare a mixed alkaline solution C of 1.0 M NaOH and 0.5 M Na2CO3.

[0096] (2) At 60℃, solution A and solution B were premixed and then co-precipitated with alkali solution C (total pH = 10.5). After the addition was completed, the mixture was stirred for 30 minutes to obtain a gray-blue slurry.

[0097] (3) After dripping, age at 70℃ for 18 hours.

[0098] (4) The product is centrifuged, washed with water and alcohol, and then vacuum dried at 60°C.

[0099] (5) The product obtained in step (4) was calcined at 450°C for 2 hours in air atmosphere, and then reduced at 400°C for 2 hours in 5% H2 / Ar atmosphere to obtain black powder NiFeCr-O.

[0100] The catalyst powders prepared in Example 1 and Comparative Example 1 were poured into an aluminum / glass sample cell, gently pressed and leveled with a glass slide, and then placed in the X-ray diffraction (XRD) instrument sample cell for testing. The results are as follows: Figure 1As shown, the material prepared by coprecipitation in Comparative Example 1 has a NiFe2O4 phase as the main phase, with only the peak intensity changing and no independent Cr2O3 phase, belonging to the NiFeCr-O solid solution phase; Example 1 uses an in-situ heterogeneous nucleation supported catalyst, which has not only a NiFe phase but also an independent Cr2O3 phase.

[0101] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the present invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A method for preparing an in-situ heterogeneous nucleation supported catalyst, characterized in that, Includes the following steps: S1, containing the first metal cation M n+ The first salt solution is mixed with the first precipitant to carry out the first precipitation reaction. The pH value of the reaction system is controlled to be 6.0-10 to generate a precursor slurry of conductive metal oxide, wherein M is selected from at least one of Cr, Mo, W and Sn. S2. Without separating the precursor slurry, a second salt solution and a second precipitant are added to it to carry out a second precipitation reaction. The pH value of the reaction system is controlled to be 10-14, and the pH value of the second reaction is higher than that of the first reaction. The second salt solution contains at least two metal cations selected from nickel, iron, cobalt, chromium, manganese, copper and zinc. S3. The product after the second step reaction is aged, separated into solid and liquid, washed, dried and heat-treated to obtain the catalyst.

2. The method for preparing an in-situ heterogeneous nucleation supported catalyst according to claim 1, characterized in that, The reaction temperature for both steps S1 and S2 is 30-90℃; in step S2, the dropping rate of the second salt solution is 0.1-5.0 mL / min.

3. The method for preparing an in-situ heterogeneous nucleation supported catalyst according to claim 1, characterized in that, The first precipitant and the second precipitant are one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonia, and ammonium carbonate, respectively.

4. The method for preparing an in-situ heterogeneous nucleation supported catalyst according to claim 1, characterized in that, In step S3, the heat treatment includes: calcining in air or an inert atmosphere at 100-600°C for 1-20 hours, followed by treatment in a reducing or inert atmosphere at 200-500°C for 0.5-3 hours.

5. An in-situ heterogeneous nucleation supported catalyst prepared by the preparation method according to any one of claims 1-4.

6. The supported catalyst for in-situ heterogeneous nucleation according to claim 5, characterized in that: It includes a conductive metal oxide carrier and transition metal-based nanoparticles uniformly loaded on its surface.

7. The supported catalyst for in-situ heterogeneous nucleation according to claim 5, characterized in that, The conductive metal oxide support is Cr2O3 or MoO. x WO x At least one of SnO2, where x is a numerical value that satisfies the stoichiometric ratio.

8. An electrode, characterized in that, It includes a conductive substrate and a supported catalyst for in-situ heterogeneous nucleation as described in claim 5, supported on the conductive substrate.

9. An electrolytic water anode, characterized in that, It includes the electrode as described in claim 8.

10. The application of the catalyst as described in claim 5, the electrode as described in claim 8, or the water electrolysis anode as described in claim 9 in a water electrolysis hydrogen production system.

Images