Method for macroscopically preparing non-noble metal-based heterogeneous catalyst by gel sintering method

Abstract

According to the interface excitation effect design concept of a high-performance heterogeneous catalyst for hydrogen production by electrolysis of water, the heterogeneous characteristic of a gel system and the confinement effect of a three-dimensional network structure are utilized, and the non-noble metal-based heterogeneous catalyst is prepared. A solution containing nucleophilic components (nickel, cobalt and the like) is confined in a gel network framework constructed by electrophilic components (molybdenum, tungsten, vanadium, cerium, iron and the like), and the confined solution and the gel framework are subjected to heterogeneous nucleation and crystallization at the same time through sintering, so that the non-noble metal-based heterogeneous catalyst is obtained through direct reduction. The catalyst prepared by the method provided by the invention has a nano size, and has better electrochemical catalytic activity and stability in alkaline and neutral water electrolysis cathode catalysis processes as an electrode material. In addition, no waste liquid is discharged in the preparation process of the catalyst, the operation is simple, the preparation is simple and convenient, the large-scale preparation of the integral water electrolysis cathode hydrogen evolution electrode material is facilitated, and the large-scale practical application of the integral water electrolysis cathode hydrogen evolution electrode material is facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and specifically relates to a method for macroscopically preparing a non-noble metal-based heterogeneous catalyst by a gel sintering method. Background Art

[0002] The new anion exchange membrane (AEM) electrolytic water hydrogen production technology has the advantages of high energy efficiency, large current, long life, etc., and can effectively connect to the fluctuating power sources generated by upstream solar energy, wind energy, and hydropower stations, improving the utilization rate of clean energy. It is the current trend of electrolytic water hydrogen production technology. The prerequisite for driving AEM hydrogen production is to develop high-performance hydrogen evolution catalysts suitable for alkaline and neutral systems. Currently, platinum-based noble metal materials are catalysts with natural hydrogen evolution activity, but their large-scale application is restricted by the scarcity of resources. Therefore, the development and macroscopic preparation of high-activity non-noble metal hydrogen evolution catalysts are the key to realizing the industrial application of AEM hydrogen production, and this is also one of the "Top Ten Electrochemical Scientific Issues" proposed by the Electrochemistry Professional Committee of the Chinese Chemical Society at the beginning of 2024.

[0003] For the design and research and development of high-efficiency non-noble metal hydrogen evolution catalysts suitable for alkaline and neutral conditions, it is not only necessary to satisfy the Sabatier principle (appropriate adsorption energy for active H* species), but also necessary to consider the dissociation process of water molecules in order to provide sufficient active H* species for the subsequent hydrogen evolution process. Therefore, heterogeneous heterojunction materials with specific structures can meet the above requirements through the interfacial excitation effect. This heterogeneous material composed of an electrophilic (oxyphilic) phase and a nucleophilic phase can adsorb the oxygen end and proton end of water molecules respectively, thus producing a strong pulling effect on water molecules and playing the role of water hydrolysis - hydrogen evolution. Based on this, a variety of heterojunction catalytic materials have been successively developed, such as Ni4W / WO3, Ni / Fe2O3, Ni4Mo / MoO2, etc. Among them, Ni4Mo / MoO2 has extremely high hydrogen evolution catalytic activity and is one of the most promising materials to replace noble metal platinum-based catalysts.

[0004] The NiMoO4 precursor is grown on a nickel foam substrate through a high-temperature and high-pressure hydrothermal reaction, and then the Ni4Mo / MoO2 catalyst is prepared by high-temperature reduction in a hydrogen atmosphere for the hydrogen evolution reaction (HER) of electrolytic water. The main phase of the catalyst phase structure is MoO2, on which Ni4Mo alloy particles are loaded. Some studies have shown that mixing ammonia gas in the later reducing atmosphere will result in a nitrogen-doped Ni4Mo / MoO2 catalyst, further improving its hydrogen evolution activity. However, the catalyst grown on nickel foam is prone to falling off during sintering and use, and the nickel foam substrate will also become brittle and lose its support, which may cause short circuits and failures in the electrolytic cell during actual application. At the same time, the customization of large-scale high-pressure vessels, the ammonia gas atmosphere (prohibited emission gas), etc. are not conducive to large-scale production, which seriously hinders the practical application of such materials in large-scale AEMs. Summary of the Invention

[0005] The object of the present invention is to provide a method for macroscopically preparing a non-noble metal-based heterogeneous catalyst by a gel sintering method. This method improves the traditional method of preparing a catalyst by high-temperature and high-pressure hydrothermal treatment followed by high-temperature reduction. A gel precursor of the target material is obtained by a concentration method, and then a heterogeneous catalyst is directly obtained by sintering under relatively mild reduction conditions. The prepared catalyst is a typical heterogeneous heterojunction nanomaterial with a large specific surface area. Moreover, this method is easy to operate, has a yield close to 100%, no waste liquid discharge, and is suitable for large-scale production.

[0006] The method for macroscopically preparing a non-noble metal-based heterogeneous catalyst by the gel sintering method provided by the present invention includes the following steps:

[0007] Step 1: Dissolve the soluble salt of the nucleophilic phase metal and the soluble salt of the electrophilic phase metal in deionized water to obtain a precursor solution; the soluble salt of the nucleophilic phase metal is a soluble salt of any one or two of Ni 2+ , Co 2+ , and the soluble salt of the electrophilic phase metal is a soluble salt of any one or more of Mo 6+ , V 5+ , W 6+ , Ce 3+ , Ce 4+ , Cr 3+ , Cr 6+ , Mn 2+ , Mn 7+ , Fe 2+ , Fe 3+ .

[0008] Step 2: Concentrate the precursor solution in Step 1 by vacuum distillation or rotary evaporation to obtain a gel concentrate;

[0009] Step 3: Sinter and reduce the gel concentrate in Step 2 to obtain a heterogeneous catalyst.

[0010] In the above Step 1, further an additive is added to the precursor solution, and the additive is any one or more of hydrochloric acid, ammonia water, citric acid, sodium citrate, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, potassium sodium tartrate, and triethanolamine. The addition of the additive can not only regulate the pH environment of different reactions, but also control the formation process of the precursor gelation.

[0011] In the above Step 1, preferably, the concentration of the soluble salt of the nucleophilic phase metal in the precursor solution is 0.001 - 5 mol / L -1 , and the concentration of the soluble salt of the electrophilic phase metal in the precursor solution is 0.001 - 5 mol / L -1, the molar ratio of the nucleophilic-phase metal element to the electrophilic-phase metal element in the precursor solution is 1 to 40:1.

[0012] In the above step 1, it is further preferred that the concentration of the soluble salt of the nucleophilic-phase metal in the precursor solution is 0.01 to 2 mol / L -1 , and the concentration of the soluble salt of the electrophilic-phase metal is 0.004 to 2 mol / L -1 , and the molar ratio of the nucleophilic-phase metal element to the electrophilic-phase metal element in the precursor solution is 1 to 20:1.

[0013] In the above step 1, it is preferred that the concentration of the additive in the precursor solution is 0.001 to 5 mol / L -1 .

[0014] In the above step 1, it is further preferred that the concentration of the additive in the precursor solution is 0.01 to 2 mol / L -1 .

[0015] In the above step 1, the soluble salt of Ni 2+ is any one or more of nickel sulfate, nickel nitrate, nickel acetate, nickel chloride, nickel sulfamate, nickel bromide; the soluble salt of Co 2+ is any one or more of cobalt nitrate, cobalt sulfate, cobalt chloride, cobalt acetate; the soluble salt of Mo 6+ is any one or two of ammonium molybdate, ammonium heptamolybdate, sodium molybdate; the soluble salt of V 5+ is any one or more of ammonium vanadate, sodium metavanadate, ammonium metavanadate, potassium metavanadate; the soluble salt of W 6+ is any one or more of ammonium tungstate, ammonium paratungstate, sodium tungstate, potassium tungstate; the soluble salt of Ce 3+ is any one or more of cerium nitrate, cerium chloride, cerium acetate, and the soluble salt of Ce 4+ is cerium sulfate; the soluble salt of Cr 3+ is any one or more of chromium nitrate, chromium chloride, chromium sulfate, and the soluble salt of Cr 6+ is sodium chromate; the soluble salt of Mn 2+ is any one or more of manganese chloride, manganese nitrate, manganese acetate, and the soluble salt of Mn 7+ is potassium permanganate; the soluble salt of Fe 3+ is any one or more of ferric chloride, ferric nitrate, and the soluble salt of Fe 2+ is ferrous chloride.

[0016] In the above step 2, it is preferred that the concentration temperature is 50 to 100 °C and the concentration time is 0.5 to 12 h.

[0017] In step 3 above, the sintering atmosphere is any one of air, nitrogen, and argon. The preferred sintering temperature is 500-700 °C, and the sintering time is 8-12 h. The reduction atmosphere is hydrogen, a mixture of hydrogen and nitrogen or argon, and the volume concentration of hydrogen in the mixture is 5%-30%. The preferred reduction temperature is 500-700 °C, and the reduction time is 2-6 h.

[0018] The present invention uses the sol-gel method to prepare a non-precious metal-based catalyst for the hydrogen evolution reaction (HER) of electrolyzed water, that is, a sol is first formed through hydrolysis and polycondensation reactions of a precursor, and then converted into a gel, and finally the catalyst is obtained through drying or heat treatment. The gel precursor is essentially a dispersion with a heterogeneous structure, in which the solvent (or solution) is confined by a three-dimensional gel network through non-covalent or covalent bonds. By adjusting the type, proportion of the precursor or doping other elements, the chemical composition of the catalyst can be accurately controlled. Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. The present invention adopts the gel sintering method to prepare a catalyst material with a heterogeneous structure in one step, without high-temperature and high-pressure hydrothermal reactions, and has the advantages of simplicity and high efficiency, and is suitable for industrial mass production of materials.

[0020] 2. The material prepared by the method of the present invention is a heterogeneous heterojunction crystal with nanoscale dispersion. During the preparation process, the yield is close to 100%, there is no waste liquid discharge, it is environmentally friendly, and meets the sustainable development goal.

[0021] 3. The catalytic material prepared by the present invention is used for the hydrogen evolution catalytic reaction of the cathode of electrolyzed water, has good electrochemically hydrogen evolution catalytic activity and stability, has the effect of high efficiency and energy saving, and can be used as a hydrogen evolution cathode catalyst for an anion exchange membrane electrolyzed water hydrogen production system.

[0022] 4. The preparation method of the heterogeneous catalyst provided by the present invention has a certain universality, and the obtained catalyst has extremely high electrochemically catalytic activity, providing an important reference for the development and mass production of high-efficiency non-precious metal-based hydrogen evolution catalysts.

[0023] 5. The catalytic material in the present invention does not use precious metal elements, has a low production cost, simple operation, wide sources of precursors, can achieve mass preparation, and is easy to industrialize. Description of the Drawings

[0024] Figure 1 It is a diagram of the precursor solution (left) and the gel concentrated product (middle and right) in Example 1, and the scale in the figure is 2 cm.

[0025] Figure 2 It is a scanning electron microscope microstructure (a) and X-ray diffraction (b) diagram of the heterogeneous nickel-molybdenum catalyst prepared in Example 1.

[0026] Figure 3 It is the energy spectrum diagram of each element corresponding to the heterogeneous nickel-molybdenum catalyst prepared in Example 1.

[0027] Figure 4 It is the scanning electron microscope microstructure (a) and X-ray diffraction (b) diagrams of the heterogeneous nickel-cerium catalyst prepared in Example 3.

[0028] Figure 5 It is the scanning electron microscope microstructure diagram of the heterogeneous nickel-molybdenum catalyst prepared in Example 5.

[0029] Figure 6 It is the X-ray diffraction comparison diagram of the heterogeneous nickel-molybdenum catalysts prepared in Example 5 and Example 1.

[0030] Figure 7 It is the scanning electron microscope microstructure (a), X-ray diffraction (b), and corresponding energy spectrum diagrams of each element (c-f) of the nickel-molybdenum catalyst prepared in Example 6.

[0031] Figure 8 It is the scanning electron microscope microstructure (a), X-ray diffraction (b), and corresponding energy spectrum diagrams of each element (c-f) of the nickel-molybdenum catalyst prepared in Comparative Example 1.

[0032] Figure 9 It is the hydrogen production performance (b) diagram of the catalyst prepared in Example 1 in an anion exchange membrane electrolytic cell (a).

[0033] Figure 10 It is the comparison diagram of the hydrogen evolution polarization curves (without iR compensation correction) of the heterogeneous nickel-molybdenum catalysts prepared in Example 5 and Example 1 in the electrolysis efficiency activity test of water electrolysis in an alkaline electrolyte (1M KOH aqueous solution).

[0034] Figure 11 It is the hydrogen evolution polarization curves (without iR compensation correction) of the commercial platinum-carbon catalyst and the catalysts prepared in Examples 1-5 in the hydrogen evolution activity test of water electrolysis in 1M KOH alkaline electrolyte.

[0035] Figure 12 It is the hydrogen evolution polarization curves (without iR compensation correction) of the catalysts prepared in Example 1, Example 6, and Comparative Example 1 in the hydrogen evolution activity test of water electrolysis in 1M KOH alkaline electrolyte.

[0036] Figure 13 It is the hydrogen evolution polarization curves (without iR compensation correction) of the commercial platinum-carbon catalyst and the catalyst prepared in Example 1 in the hydrogen evolution activity test of water electrolysis in 1M PBS neutral electrolyte. Detailed implementation manners

[0037] The present invention will be described in detail below with reference to the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments only.

[0038] Example 1

[0039] Preparation of heterogeneous nickel-molybdenum catalyst

[0040] Step 1: Nickel nitrate and ammonium heptamolybdate with a Ni:Mo molar ratio of 4:1 are added to deionized water. After stirring and fully dissolving, ammonia water is added to prepare 250 mL of a precursor solution. The concentration of nickel nitrate in the precursor solution is 0.2 mol / L -1 , the concentration of ammonium heptamolybdate is 0.007 mol / L -1 , and the concentration of ammonia water is 0.05 mol / L -1 .

[0041] Step 2: The precursor solution in Step 1 is concentrated by means of vacuum distillation. The concentration temperature is 65 °C, the concentration time is 1 h, and the rotation rate is 200 rpm to obtain a gel concentrated product.

[0042] Step 3: The gel concentrated product in Step 2 is placed in a muffle furnace for sintering. The sintering atmosphere is air, the sintering temperature is 550 °C, and the sintering time is 10 h to obtain a powder product; the powder product is continuously placed in a tubular furnace for reduction. The reduction atmosphere is a mixed gas of hydrogen and argon, and the volume concentration of hydrogen in the mixed gas is 5%. The reduction temperature is 500 °C, and the reduction time is 2 h to obtain 4.0 g of a heterogeneous nickel-molybdenum catalyst.

[0043] As Figure 1 can be seen, during the preparation process of the heterogeneous nickel-molybdenum catalyst, the precursor solution is concentrated to obtain a gel-state concentrated product after concentration. As Figure 2 shown, the prepared heterogeneous nickel-molybdenum catalyst is a nanoparticle accumulation structure, and its XRD analysis mainly has three phases: Ni, MoO2, and a small amount of NiO (generated by the oxidation of Ni on the surface). Figure 3 is the TEM morphology diagram of this catalyst and the EDX area scan of each element. The experimental results show that this catalyst contains Mo, Ni, O, and N elements. At the same time, an enriched metal phase Ni signal appears in the central area, while the Mo signal becomes weak in the same area, and the Mo and O signals are modified around Ni, indicating that MoO2 nanoparticles (or a small amount of NiO) are loaded on metallic Ni. At the same time, in Figure 3 (f), we can observe and detect the signal of N, indicating the successful doping of N atoms. In summary, the catalyst prepared in this example is a heterogeneous structure, with metallic Ni as the main phase in the phase structure, MoO2 particles loaded thereon, and the successful doping of N is achieved during the preparation process of the catalyst.

[0044] Example 2

[0045] Preparation of Heterogeneous Nickel-Tungsten Catalyst

[0046] Step 1: Nickel nitrate and ammonium metatungstate with a Ni:W molar ratio of 4:1 were added to deionized water, and stirred until fully dissolved to prepare a 250 mL precursor solution. The concentration of nickel nitrate in the precursor solution was 0.2 mol / L -1 , and the concentration of ammonium metatungstate was 0.0042 mol / L -1 .

[0047] Step 2: The precursor solution in Step 1 was concentrated by rotary evaporation at a concentration temperature of 70 °C, a concentration time of 1 h, and a rotation rate of 150 rpm to obtain a gel concentrated product.

[0048] Step 3: The gel concentrated product in Step 2 was sintered in a muffle furnace with an air sintering atmosphere, a sintering temperature of 550 °C, and a sintering time of 12 h to obtain a powder product; the powder product was then further reduced in a tubular furnace with a mixed gas of hydrogen and argon as the reduction atmosphere, the volume concentration of hydrogen in the mixed gas was 20%, the reduction temperature was 500 °C, and the reduction time was 3 h to obtain 5.0 g of heterogeneous nickel-tungsten catalyst.

[0049] Example 3

[0050] Preparation of Heterogeneous Nickel-Cerium Catalyst

[0051] Step 1: Nickel nitrate and cerium nitrate with a Ni:Ce molar ratio of 16:1 were added to deionized water, and after stirring until fully dissolved, sodium citrate was added to prepare a 250 mL precursor solution. The concentration of nickel nitrate in the precursor solution was 0.8 mol / L -1 , the concentration of cerium nitrate was 0.05 mol / L -1 , and the concentration of sodium citrate was 0.1 mol / L -1 .

[0052] Step 2: The precursor solution in Step 1 was concentrated by vacuum distillation at a concentration temperature of 75 °C, a concentration time of 2 h, and a rotation rate of 200 rpm to obtain a gel concentrated product.

[0053] Step 3: The gel concentrated product in Step 2 was sintered in a muffle furnace with an air sintering atmosphere, a sintering temperature of 600 °C, and a sintering time of 10 h to obtain a powder product; the powder product was then further reduced in a tubular furnace with a mixed gas of hydrogen and argon as the reduction atmosphere, the volume concentration of hydrogen in the mixed gas was 5%, the reduction temperature was 700 °C, and the reduction time was 2 h to obtain 10.0 g of heterogeneous nickel-cerium catalyst. It can be Figure 4 seen that the prepared heterogeneous nickel-cerium catalyst has an irregular nano-block morphology, and its XRD analysis mainly shows two phases of Ni and CeO2.

[0054] Example 4

[0055] Preparation of Heterogeneous Nickel-Molybdenum-Iron Catalyst

[0056] Step 1: Nickel nitrate, ammonium heptamolybdate and iron nitrate with a molar ratio of Ni:Mo:Fe of 80:20:1 were added to deionized water and stirred until fully dissolved to prepare a 250 mL precursor solution. The concentration of nickel nitrate in the precursor solution was 0.2 mol / L -1 , the concentration of ammonium heptamolybdate was 0.007 mol / L -1 , and the concentration of iron nitrate was 0.0025 mol / L -1 .

[0057] Step 2: The precursor solution in Step 1 was concentrated by rotary evaporation at a concentration temperature of 65 °C, a concentration time of 1 h, and a rotation rate of 200 rpm to obtain a gel concentrated product.

[0058] Step 3: The gel concentrated product in Step 2 was placed in a muffle furnace for sintering. The sintering atmosphere was air, the sintering temperature was 500 °C, and the sintering time was 10 h to obtain a powder product; the powder product was then placed in a tubular furnace for reduction. The reduction atmosphere was a mixture of hydrogen and argon, the volume concentration of hydrogen in the mixture was 5%, the reduction temperature was 550 °C, and the reduction time was 2 h to obtain 4.0 g of heterogeneous nickel-molybdenum-iron catalyst.

[0059] Example 5

[0060] Macroscale Preparation of Heterogeneous Nickel-Molybdenum Catalyst

[0061] Step 1: Nickel nitrate and ammonium heptamolybdate with a molar ratio of Ni:Mo of 4:1 were added to deionized water. After stirring until fully dissolved, ammonia water was added to prepare a 1 L precursor solution. The concentration of nickel nitrate in the precursor solution was 1 mol / L -1 , the concentration of ammonium heptamolybdate was 0.035 mol / L -1 , and the concentration of ammonia water was 0.25 mol / L -1 .

[0062] Step 2: The precursor solution in Step 1 was concentrated by vacuum distillation at a concentration temperature of 65 °C, a concentration time of 5 h, and a rotation rate of 200 rpm to obtain a gel concentrated product.

[0063] Step 3: Place the gel concentrated product from Step 2 in a muffle furnace for sintering. The sintering atmosphere is air, the sintering temperature is 550 °C, and the sintering time is 10 h to obtain a powder product. Then continue to place the powder product in a tube furnace for reduction. The reduction atmosphere is a mixture of hydrogen and argon, the volume concentration of hydrogen in the mixture is 5%, the reduction temperature is 500 °C, and the reduction time is 2 h to obtain approximately 80.0 g of heterogeneous nickel-molybdenum catalyst. From Figure 5 It can be seen that the heterogeneous nickel-molybdenum catalyst prepared in this example has a nanoparticle accumulation structure, which is similar to the structure of the heterogeneous nickel-molybdenum catalyst prepared in Example 1 ( Figure 2 (a)), and its XRD analysis ( Figure 6 ) is consistent with that of Example 1 ( Figure 2 (b)), indicating that the main existing phases of the two catalysts are the same. Thus, it can be seen that the method for preparing a heterogeneous nickel-molybdenum catalyst by expanding the concentration and volume in this example is feasible, and there is no difference in the structure between the catalyst prepared by macroscale preparation and the catalyst prepared in a small laboratory scale in Example 1.

[0064] Example 6

[0065] Preparation of Heterogeneous Nickel-Molybdenum Catalyst

[0066] Step 1: Add nickel nitrate and sodium molybdate with a Ni:Mo molar ratio of 4:1 to deionized water. After stirring and fully dissolving, add ammonia water to prepare a 250 mL precursor solution. The concentration of nickel nitrate in the precursor solution is 0.2 mol / L -1 , the concentration of sodium molybdate is 0.05 mol / L -1 , and the concentration of ammonia water is 0.05 mol / L -1 .

[0067] Step 2: Concentrate the precursor solution from Step 1 by vacuum distillation. The concentration temperature is 65 °C, the concentration time is 1 h, and the rotation rate is 200 rpm to obtain a gel concentrated product.

[0068] Step 3: Place the gel concentrated product from Step 2 in a muffle furnace for sintering. The sintering atmosphere is air, the sintering temperature is 550 °C, and the sintering time is 10 h to obtain a powder product. Then continue to place the powder product in a tube furnace for reduction. The reduction atmosphere is a mixture of hydrogen and argon, the volume concentration of hydrogen in the mixture is 5%, the reduction temperature is 500 °C, and the reduction time is 2 h to obtain 4.0 g of heterogeneous nickel-molybdenum catalyst. From Figure 7 (a), it can be seen that the catalyst presents a nanocluster structure and there is no obvious dispersion of small particles. Figure 7 (b) is the XRD pattern of the catalyst. From the figure, we can see that the main phases are Na2MoO4 and Ni, and in addition, there is a small amount of NiO generated by the oxidation of surface Ni. Figure 7(c - f) are the EDX area scans of each element. The results show that the catalyst contains three elements, Mo, Ni, and O, and no N element signal can be observed. Compared with Example 1, this catalyst is a non-nitrogen-doped heterogeneous nickel-molybdenum catalyst. Figure 7 (d) is the energy spectrum superposition diagram of Ni and Mo elements. We can find that the signal of Mo is much more than that of Ni.

[0069] Comparative Example 1

[0070] Take about 1.0 g of commercial NiMoO4 powder and place it in a tubular furnace for reduction. The reduction atmosphere is a mixture of hydrogen and argon. The volume concentration of hydrogen in the mixture is 5%, the reduction temperature is 500 °C, and the reduction time is 2 h to obtain nickel-molybdenum catalyst powder. From Figure 8 (a), it can be seen that the catalyst shows a state of nanoparticle aggregation, with an irregular morphology, and the sizes of different particles are different. Figure 8 (b) is the XRD pattern of the catalyst prepared from commercial NiMoO4 precursor. Compared with Figure 2 (b), the diffraction peak intensity of MoO2 is much larger. Combining the elemental Mapping analysis in Figure 8 (c - f), the signal of Mo element is much larger than that of Ni. Therefore, it can be obtained that in the phase composition of the nickel-molybdenum catalyst prepared from commercial NiMoO4 precursor, the main phase is MoO2, with a small amount of elemental Ni particles loaded on it, and no signal of N element can be observed.

[0071] To verify the actual operation of the heterogeneous nickel-molybdenum catalyst prepared in Example 1 in an anion exchange membrane electrolyzer, as shown in Figure 9 (a), the cathode heterogeneous nickel-molybdenum catalyst powder and the anode commercial nickel-iron catalyst powder are coupled with an anion exchange membrane of model PiperION-40μm by ultrasonic spraying method. A nickel felt is used as the cathode diffusion layer, and a carbon fiber paper is used as the anode diffusion layer to build an anion exchange membrane electrolyzer device. The electrolyte enters from the cathode side unilaterally. HER and OER reactions occur on the surfaces of the heterogeneous nickel-molybdenum catalyst and the commercial nickel-iron catalyst respectively. The gas products are discharged from the electrolyzer with the electrolyte and pipelines. The reaction temperature is set at 80 °C, and the peristaltic pump speed is set at 3 sscm. In 0.1 M KOH electrolyte, the initial potential of anion exchange membrane water electrolysis is about 1.4 V, and when the cell voltage is 2 V, a current density of 1.1 A cm -2 can be achieved ( Figure 9 (b)).

[0072] Take 10 mg each of the catalysts of Examples 1-6 and Comparative Example 1 and the commercial platinum-carbon catalyst, and add them to a dispersion of deionized water, ethanol, and Nafion® D-520 with a volume ratio of 12:12:1 to prepare a 1 mL solution. Ultrasonicate this solution for 30 min to obtain a black and homogeneous slurry. Load 4.5 μL of this slurry onto a glassy carbon electrode (GC) with a diameter of 3 mL for the electrolytic water hydrogen evolution efficiency activity test. The results are shown in Figures 10 - 13 .

[0073] As Figure 10 shown, the alkaline hydrogen evolution polarization curve of the heterogenous nickel-molybdenum catalyst prepared in large quantities in Example 5 basically coincides with that in Example 1, indicating that the heterogenous nickel-molybdenum catalyst prepared in large quantities has the same hydrogen evolution activity as the sample prepared in small laboratory doses.

[0074] In Figure 11 , curves 1-5 are the alkaline hydrogen evolution polarization curves of the commercial platinum-carbon catalyst, the heterogenous nickel-molybdenum catalyst prepared in Example 1, the heterogenous nickel-tungsten catalyst prepared in Example 2, the heterogenous nickel-cerium catalyst prepared in Example 3, and the heterogenous nickel-molybdenum-iron catalyst prepared in Example 4, respectively. Among them, the initial overpotential (η) of the heterogenous nickel-molybdenum catalyst loaded on the glassy carbon electrode in Example 1 is close to 0 mV, and its hydrogen evolution activity is better than that of the commercial platinum-carbon catalyst. The hydrogen evolution activities of the other catalysts are not much different from that of the commercial platinum-carbon catalyst.

[0075] In Figure 12 , curves 1-3 are the alkaline hydrogen evolution polarization curves of the nickel-molybdenum catalyst prepared in Example 1, the nickel-molybdenum catalyst prepared in Comparative Example 1, and the nickel-molybdenum catalyst prepared in Example 6, respectively. As can be seen from the figure, the alkaline hydrogen evolution activity of the heterogenous nickel-molybdenum catalyst prepared in Example 1 is significantly better than that of the nickel-molybdenum catalysts prepared in Comparative Example 1 and Example 6. This shows that the heterogenous structure of the catalyst prepared in Example 1 and the successful doping of nitrogen element endow the catalyst with higher HER catalytic activity.

[0076] In Figure 13 , curves 1-2 are the neutral hydrogen evolution polarization curves of the commercial platinum-carbon catalyst and the heterogenous nickel-molybdenum catalyst prepared in Example 1, respectively. As can be seen from the figure, the initial overpotential (η) of the heterogenous nickel-molybdenum catalyst loaded on the glassy carbon electrode is slightly greater than 0 mV, and its hydrogen evolution activity is close to that of the commercial platinum-carbon catalyst in the neutral electrolyte.

Claims

1. A method for macroscopically preparing a non-noble metal-based heterogeneous catalyst by gel sintering method, characterized in that, The method comprises the following steps: Step 1: Dissolve the soluble salt of the nucleophilic-phase metal and the soluble salt of the electrophilic-phase metal in deionized water to obtain a precursor solution; the soluble salt of the nucleophilic-phase metal is Ni 2+ , Co 2+ , any one or two of the soluble salts, and the soluble salt of the electrophilic-phase metal is Mo 6+ , V 5+ , W 6+ , Ce 3+ , Ce 4+ , Cr 3+ , Cr 6+ , Mn 2+ , Mn 7+ , Fe 2+ , Fe 3+ , any one or more of the soluble salts; Step 2: Concentrate the precursor solution in Step 1 by means of reduced pressure distillation or rotary evaporation to obtain a gel concentrated product; Step 3: Sinter and reduce the gel concentrated product in Step 2 to obtain a heterogeneous catalyst.

2. The method for macroscopically preparing a non-noble metal-based heterogeneous catalyst by gel sintering according to claim 1, wherein In Step 1, an additive is added to the precursor solution, and the additive is any one or more of hydrochloric acid, ammonia water, citric acid, sodium citrate, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, potassium sodium tartrate, and triethanolamine.

3. The method for macroscopically preparing a non-noble metal-based heterogeneous catalyst by gel sintering according to claim 1 or 2, characterized in that, In Step 1, the concentration of the soluble salt of the nucleophilic-phase metal in the precursor solution is 0.001 to 5 mol / L -1 and the concentration of the soluble salt of the electrophilic-phase metal is 0.001 to 5 mol / L -1 , and the molar ratio of the nucleophilic-phase metal element to the electrophilic-phase metal element in the precursor solution is 1 to 40:

1.

4. The method for macroscopically preparing a non-noble metal-based heterogeneous catalyst by gel sintering according to claim 3, characterized in that, In Step 1, the concentration of the soluble salt of the nucleophilic-phase metal in the precursor solution is 0.01 to 2 mol / L -1 and the concentration of the soluble salt of the electrophilic-phase metal is 0.004 to 2 mol / L -1 , and the molar ratio of the nucleophilic-phase metal element to the electrophilic-phase metal element in the precursor solution is 1 to 20:

1.

5. The method for macroscopically preparing a non-noble metal-based heterogeneous catalyst by gel sintering according to claim 2, characterized in that, In Step 1, the concentration of the additive in the precursor solution is 0.001 to 5 mol L -1 .

6. The method for macroscopically preparing a non-noble metal-based heterogeneous catalyst by gel sintering according to claim 5, characterized in that, In Step 1, the concentration of the additive in the precursor solution is 0.01 to 2 mol L -1 .

7. The method for macroscopically preparing a non-noble metal-based heterogeneous catalyst by gel sintering according to claim 1 or 2, characterized in that, In Step 1, the soluble salt of Ni 2+ is any one or more of nickel sulfate, nickel nitrate, nickel acetate, nickel chloride, nickel sulfamate, and nickel bromide; the soluble salt of Co 2+ is any one or more of cobalt nitrate, cobalt sulfate, cobalt chloride, and cobalt acetate; the soluble salt of Mo 6+ is any one or two of ammonium molybdate, ammonium heptamolybdate, and sodium molybdate; the soluble salt of V 5+ is any one or more of ammonium metavanadate, sodium metavanadate, ammonium metavanadate, and potassium metavanadate; the soluble salt of W 6+ is any one or more of ammonium tungstate, ammonium metatungstate, sodium tungstate, and potassium tungstate; the soluble salt of Ce 3+ is any one or more of cerium nitrate, cerium chloride, and cerium acetate, and the soluble salt of Ce 4+ is cerium sulfate; the soluble salt of Cr 3+ is any one or more of chromium nitrate, chromium chloride, and chromium sulfate, and the soluble salt of Cr 6+ is sodium chromate; the soluble salt of Mn 2+ is any one or more of manganese chloride, manganese nitrate, and manganese acetate, and the soluble salt of Mn 7+ is potassium permanganate; the soluble salt of Fe 3+ is any one or more of ferric chloride and ferric nitrate, and the soluble salt of Fe 2+ is ferrous chloride.

8. The method for macroscopically preparing a non-noble metal-based heterogeneous catalyst by gel sintering according to claim 1 or 2, characterized in that, In Step 2, the temperature of concentration is 50 - 100 °C, and the concentration time is 0.5 - 12 h.

9. The method for macroscopically preparing a non-noble metal-based heterogeneous catalyst by gel sintering according to claim 1 or 2, characterized in that, In Step 3, the sintering atmosphere is any one of air, nitrogen, and argon, the sintering temperature is 500 - 700 °C, and the sintering time is 8 - 12 h.

10. The method for macroscopically preparing a non-noble metal-based heterogeneous catalyst by gel sintering according to claim 1 or 2, characterized in that, In Step 3, the reduction atmosphere is hydrogen, a mixture of hydrogen and nitrogen or argon, the volume concentration of hydrogen in the mixture is 5% - 30%, the reduction temperature is 500 - 700 °C, and the reduction time is 2 - 6 h.

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