Ultrafine nickel-doped ruthenium oxide water electrolysis hydrogen production catalyst prepared by template method and application of ultrafine nickel-doped ruthenium oxide water electrolysis hydrogen production catalyst

Abstract

The invention relates to the technical field of electrochemical catalysis, in particular to a superfine nickel-doped ruthenium oxide water electrolysis hydrogen production catalyst prepared through a template method and application of the catalyst, the catalyst comprises a RuO2 matrix and a nickel element evenly doped in the matrix, and the mass of the nickel element accounts for 5%-20% of the total mass of the catalyst. According to the invention, the nickel element is doped into a RuO2 lattice, so that the charge distribution of RuO2 is optimized, the intrinsic activity of a catalytic active site is improved, and the catalytic performance of the oxygen evolution electrocatalyst of the material is improved; and meanwhile, ZIF8 is used as a template sacrificial agent, so that agglomeration among the nano-particles is reduced, and the uniformly dispersed metal nano-particles can be prepared.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical catalysis, and in particular to a template method for preparing an ultrafine nickel-doped ruthenium oxide water electrolysis hydrogen production catalyst and application thereof. Background Art

[0002] With the continuous development of society, the growing energy demand of mankind has led to the rapid consumption of fossil fuels. At the same time, the pollution caused by the burning of fossil fuels has led to serious global environmental problems. In order to alleviate the serious dependence of mankind on natural resources, the exploration of clean renewable energy technology is particularly urgent. Various energy storage and conversion technologies are becoming more and more widely used, such as solar cells, lithium-ion batteries, supercapacitors, fuel cells, metal-air batteries, water electrolysis to produce hydrogen, etc. Among them, the oxygen evolution reaction (OER) is the key reaction step in the electrolysis of water to produce hydrogen. Its reaction process is complex, the energy barrier is high, and it usually requires a large overpotential drive.

[0003] Currently, commercial OER catalysts are RuO2 or IrO2, but their high price, low precious metal storage, unsatisfactory catalytic performance, and short life limit their widespread application. Therefore, the development of high-performance, low-precious metal content, and low-cost oxygen evolution electrocatalysts is the key to promoting the development of hydrogen production by water electrolysis. Summary of the invention

[0004] The technical problem to be solved by the present invention is: how to reduce the content of precious metals in oxygen evolution electrocatalysts while improving their catalytic performance. The present invention uses ZIF8 with dodecahedral characteristics as a template sacrificial agent, which can effectively adsorb ruthenium and nickel metal precursors to inhibit the agglomeration between nanoparticles, thereby achieving the effect of preparing uniformly dispersed ultrafine nanoparticle catalysts. At the same time, nickel doping optimizes the charge distribution of the material, and the uniformly dispersed ultrafine nanoparticle catalysts can fully expose the active sites and fully contact and react with the electrolyte, thereby improving the intrinsic activity of the catalytic sites. The prepared oxygen evolution electrocatalyst has excellent catalytic performance, surpassing commercial RuO2. When used in water electrolysis to produce hydrogen, it greatly reduces the overpotential of the oxygen evolution reaction and improves the efficiency of the water electrolysis reaction.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a nickel-doped ruthenium oxide water electrolysis hydrogen production catalyst, the catalyst comprising a RuO2 matrix and nickel elements uniformly doped in the matrix, the mass of the nickel elements being 5%-20% of the total mass of the catalyst.

[0006] The above-mentioned method for preparing a nickel-doped ruthenium oxide water electrolysis hydrogen production catalyst comprises the following steps:

[0007] S1: Weigh zinc salt, dimethylimidazole and deionized water, mix and stir, centrifuge and dry to obtain a sacrificial template ZIF8;

[0008] S2: Add ZIF8 to deionized water, then add ruthenium salt and nickel salt, stir at room temperature for reaction, centrifuge, wash and dry to obtain a precursor material loaded with ruthenium and nickel;

[0009] S3: Sintering the precursor material to obtain nickel-doped ruthenium oxide water electrolysis hydrogen production catalyst Ni-RuO2.

[0010] Preferably, the mass ratio of the zinc salt to dimethylimidazole is 1:0.8-1.5, and the concentration of the zinc salt in deionized water is 0.01-0.1 g / ml.

[0011] Preferably, the zinc salt is one or more of zinc nitrate hexahydrate, zinc chloride hexahydrate, and zinc acetate hexahydrate.

[0012] Preferably, the concentration of ZIF8 in deionized water is 0.001-0.1 g / mL.

[0013] Preferably, the mass ratio of the ZIF8 to the ruthenium salt is 2 to 10:1, and the mass ratio of the ruthenium salt to the nickel salt is 5 to 20:1.

[0014] Preferably, the ruthenium salt is one or more of ruthenium chloride, bis(pentamethylcyclopentene)ruthenium, bis(cyclooctene)ruthenium, and (1,5-cyclooctadiene)ruthenium chloride.

[0015] Preferably, the nickel salt is one or more of nickel nitrate hexahydrate, nickel chloride hexahydrate, and nickel acetate hexahydrate.

[0016] Preferably, the sintering treatment is carried out at a temperature of 500-900° C., for a time of 2-8 h, at a heating rate of 3-5° C. / min, and in an air atmosphere.

[0017] Any of the above nickel-doped ruthenium oxide water electrolysis hydrogen production catalysts is used in the oxygen evolution reaction at the water electrolysis anode.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention dopes nickel into the RuO2 lattice, optimizes the charge distribution of RuO2 and increases the intrinsic activity of the catalytic active sites, thereby improving the catalytic performance of the oxygen evolution electrocatalyst of the material. At the same time, nickel doping reduces the amount of metal ruthenium used, reduces the production cost and is suitable for large-scale preparation;

[0020] (2) The present invention uses ZIF8 as a template sacrificial agent. ZIF8 has dodecahedral characteristics and can be used as a carrier to effectively and evenly disperse and adsorb ruthenium salt and nickel salt metal precursors, thereby achieving the purpose of reducing the agglomeration between nanoparticles and effectively dispersing metal nanoparticles, creating conditions for the preparation of ultrafine and evenly dispersed nanoparticle catalysts. The template can be removed by calcination in an air atmosphere, and no inert gas protection such as nitrogen and argon is required, further reducing the production cost.

[0021] (3) The catalyst prepared by the present invention is used as a catalyst for the anode reaction of water electrolysis. Compared with the commercial RuO2 catalyst, it greatly reduces the overpotential during the oxygen evolution reaction, reduces the power consumption of the water electrolysis reaction, improves the reaction efficiency, and reduces the cost of the anode catalyst. It is an ideal oxygen evolution reaction (OER) catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the scanning electron microscope image of Ni-RuO2;

[0023] Figure 2 This is the transmission electron microscope image of Ni-RuO2;

[0024] Figure 3 This is the transmission electron microscope energy spectrum of Ni-RuO2;

[0025] Figure 4 Oxygen evolution reaction linear voltammetry (OER-LSV) curves of Ni-RuO2 prepared in Example 1, the catalyst prepared in Comparative Example 1, and commercial RuO2;

[0026] Figure 5 Electrochemical impedance spectroscopy of Ni-RuO2 and commercial RuO2. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Embodiment 1:

[0029] Preparation of nickel-doped ruthenium oxide catalyst for water electrolysis and hydrogen production:

[0030] (1) zinc nitrate hexahydrate (4.0 g), dimethylimidazole (5.0 g) and deionized water (400.0 mL) were mixed and magnetically stirred for 8 hours, then centrifuged, washed with deionized water, and then dried at 60° C. for 8 hours to obtain ZIF8;

[0031] (2) ZIF8 (1.0 g) was added to deionized water (1000 mL), followed by the addition of hydrated ruthenium chloride (0.5 g) and nickel nitrate hexahydrate (0.1 g), magnetically stirred for 12 hours, then centrifuged, washed with deionized water, and then dried at 60° C. for 6 hours to obtain a precursor material loaded with ruthenium nickel;

[0032] (3) Under air conditions, the product of step (2) is placed in a quartz boat, placed in a muffle furnace, heated to 500°C at a heating rate of 3°C / min, and calcined at 500°C for 2 hours. After calcination, it is naturally cooled to room temperature to obtain a nickel-doped ruthenium oxide oxygen evolution water electrolysis catalyst (labeled sample as Ni-RuO2).

[0033] Embodiment 2:

[0034] Preparation of nickel-doped ruthenium oxide catalyst for water electrolysis and hydrogen production:

[0035] (1) zinc chloride hexahydrate (5.0 g), dimethylimidazole (5.0 g) and deionized water (100.0 mL) were mixed and magnetically stirred for 12 hours, then centrifuged, washed with deionized water, and then dried at 60° C. for 8 hours to obtain ZIF8;

[0036] (2) ZIF8 (1.2 g) was added to deionized water (240 mL), followed by the addition of bis(pentamethylcyclopentene)ruthenium (0.24 g) and nickel chloride hexahydrate (0.024 g), magnetically stirred for 8 hours, then centrifuged, washed with deionized water, and then dried at 60° C. for 8 hours to obtain a ruthenium-nickel-loaded precursor material;

[0037] (3) Under air conditions, the product of step (2) is placed in a quartz boat, placed in a muffle furnace, heated to 700° C. at a heating rate of 4° C. / min, and calcined at 700° C. for 4 hours. After calcination, it is naturally cooled to room temperature to obtain a nickel-doped ruthenium oxide oxygen evolution water electrolysis catalyst.

[0038] Embodiment 3:

[0039] Preparation of nickel-doped ruthenium oxide catalyst for water electrolysis and hydrogen production:

[0040] (1) zinc acetate hexahydrate (5.0 g), dimethylimidazole (4.2 g) and deionized water (60.0 mL) were mixed and magnetically stirred for 8 hours, then centrifuged, washed with deionized water, and then dried at 60° C. for 8 hours to obtain ZIF8;

[0041] (2) ZIF8 (1.5 g) was added to deionized water (200 mL), followed by the addition of bis(cyclopentadienyl)ruthenium (0.1875 g) and nickel acetate hexahydrate (0.0125 g), magnetically stirred for 8 hours, then centrifuged, washed with deionized water, and then dried at 60° C. for 8 hours to obtain a precursor material loaded with ruthenium nickel;

[0042] (3) Under air conditions, the product of step (2) is placed in a quartz boat, placed in a muffle furnace, heated to 800° C. at a heating rate of 5° C. / min, and calcined at 800° C. for 6 hours. After calcination, it is naturally cooled to room temperature to obtain a nickel-doped ruthenium oxide oxygen evolution water electrolysis catalyst.

[0043] Embodiment 4:

[0044] Preparation of nickel-doped ruthenium oxide catalyst for water electrolysis and hydrogen production:

[0045] (1) Zinc nitrate hexahydrate (6.0 g), dimethylimidazole (4.0 g) and deionized water (60.0 mL) were mixed and magnetically stirred for 8 hours, then centrifuged, washed with deionized water, and then dried at 60° C. for 8 hours to obtain ZIF8;

[0046] (2) ZIF8 (2.0 g) was added to deionized water (20 mL), followed by the addition of (1,5-cyclooctadiene)ruthenium chloride (0.2 g) and nickel nitrate hexahydrate (0.01 g), magnetically stirred for 8 hours, then centrifuged, washed with deionized water, and then dried at 60° C. for 8 hours to obtain a ruthenium-nickel-loaded precursor material;

[0047] (3) Under air conditions, the product of step (2) is placed in a quartz boat, placed in a muffle furnace, heated to 900° C. at a heating rate of 5° C. / min, and calcined at 900° C. for 8 hours. After calcination, it is naturally cooled to room temperature to obtain a nickel-doped ruthenium oxide oxygen evolution water electrolysis catalyst.

[0048] Comparative Example 1:

[0049] The difference from Example 1 is that the catalyst for hydrogen production by electrolysis of water is directly prepared without using ZIF8 as a template;

[0050] (1) adding hydrated ruthenium chloride (0.5 g) and nickel nitrate hexahydrate (0.1 g) to deionized water (20 mL), stirring with a magnetic force for 12 hours, then evaporating the deionized water, and then drying at 60° C. for 6 hours to obtain a ruthenium nickel precursor material;

[0051] (2) Under air conditions, the product of step (1) is placed in a quartz boat, placed in a muffle furnace, heated to 500° C. at a heating rate of 3° C. / min, and calcined at 500° C. for 2 hours. After calcination, it is naturally cooled to room temperature to obtain a water electrolysis hydrogen production catalyst.

[0052] Catalyst structure characterization:

[0053] Figure 1 This is a scanning electron microscope image of the nickel-doped ruthenium oxide oxygen evolution and water electrolysis catalyst (Ni-RuO2) prepared in Example 1. It can be seen that the catalyst nanoparticles are well dispersed and present a uniform and fine spherical nanoparticle structure.

[0054] Figure 2 This is the transmission electron microscope image of the nickel-doped ruthenium oxide oxygen evolution and water electrolysis catalyst (Ni-RuO2) prepared in Example 1. It can be seen that the nanoparticles of the catalyst are very uniform and fine, with a particle size of about 10 nm and good morphology consistency of the nanoparticles.

[0055] Figure 3 The transmission electron microscope energy spectrum image of the nickel-doped ruthenium oxide oxygen evolution water electrolysis catalyst (Ni-RuO2) prepared in Example 1 shows that the nickel element is very evenly doped in the RuO2 lattice, which plays a very important role in optimizing the charge distribution of the material and improving the intrinsic activity of the catalytic site, thereby further improving the catalytic performance of the material in the oxygen evolution reaction.

[0056] Catalyst performance test:

[0057] Take 1.0 mg of the nickel-doped ruthenium oxide oxygen electrolysis water catalyst (Ni-RuO2) prepared in Example 1, the catalyst prepared in Comparative Example 1, and the commercial RuO2 catalyst, respectively, and then disperse them in 200 microliters of ethanol and 9.8 microliters of NaFion solution. After ultrasonic mixing, take 20 microliters of slurry and apply it on the rotating disk electrode. After it is completely dried, measure its oxygen evolution reaction linear voltammetry (OER-LSV) curve on the electrochemical workstation. The determination of the oxygen evolution reaction linear voltammetry (OER-LSV) curve uses a saturated Ag / AgCl electrode as a reference electrode, a Pt electrode as a counter electrode, a scan rate of 5mV / s, and an electrolyte of 1mol / L KOH solution.

[0058] The oxygen evolution reaction linear voltammetry (OER-LSV) curve obtained by the test is as follows: Figure 4 As shown in the figure, it can be clearly seen that the nickel-doped ruthenium oxide oxygen evolution water electrolysis catalyst (Ni-RuO2) in 1M KOH solution is 10mA / cm 2The overpotential of the commercial RuO2 catalyst under the same conditions is 240mV, while the overpotential of the commercial RuO2 catalyst is 300mV, which is 60mV lower, effectively reducing the overpotential of the oxygen evolution reaction, and the performance is significantly better than that of the commercial RuO2 catalyst. 2 The overpotential is 340mV, which is 100mV higher than the nickel-doped ruthenium oxide oxygen evolution water electrolysis catalyst (Ni-RuO2) prepared by the ZIF8 template method, and 40mV higher than the commercial RuO2 catalyst. This is because without ZIF8 as a template, the ruthenium salt and nickel salt precursors will rapidly agglomerate during the high-temperature calcination process to form a bulk material with huge particles, which has a relatively small specific surface area and fewer active sites. At the same time, the active sites cannot be fully exposed, and the contact effect with the electrolyte is also poor, so it shows a poor catalytic effect.

[0059] Figure 5 From the electrochemical impedance spectra of the nickel-doped ruthenium oxide oxygen evolution water electrolysis catalyst (Ni-RuO2) prepared in Example 1 and commercial RuO2 under the same test conditions, it can be clearly seen that the charge transfer impedance of the nickel-doped ruthenium oxide oxygen evolution water electrolysis catalyst is much smaller, indicating that it has faster electron transfer performance than commercial RuO2, and also proving that its catalytic activity is higher.

[0060] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

Claims

1. A nickel-doped ruthenium oxide catalyst for electrolyzing water to produce hydrogen, characterized in that: The catalyst comprises a RuO2 matrix and nickel elements uniformly doped in the matrix, and the mass of the nickel elements accounts for 5% to 20% of the total mass of the catalyst.

2. The method for preparing a nickel-doped ruthenium oxide catalyst for electrolyzing water to produce hydrogen according to claim 1, characterized in that: The steps include: S1: Weigh zinc salt, dimethylimidazole and deionized water, mix and stir, centrifuge and dry to obtain a sacrificial template ZIF8; S2: Add ZIF8 to deionized water, then add ruthenium salt and nickel salt, stir at room temperature for reaction, centrifuge, wash and dry to obtain a precursor material loaded with ruthenium and nickel; S3: Sintering the precursor material to obtain nickel-doped ruthenium oxide water electrolysis hydrogen production catalyst Ni-RuO2.

3. The method for preparing a nickel-doped ruthenium oxide catalyst for electrolyzing water to produce hydrogen according to claim 2, characterized in that: The mass ratio of the zinc salt to dimethylimidazole is 1:0.8-1.5, and the concentration of the zinc salt in deionized water is 0.01-0.1 g / ml.

4. The method for preparing a nickel-doped ruthenium oxide catalyst for electrolyzing water to produce hydrogen according to claim 2, characterized in that: The zinc salt is one or more of zinc nitrate hexahydrate, zinc chloride hexahydrate, and zinc acetate hexahydrate.

5. The method for preparing a nickel-doped ruthenium oxide catalyst for electrolyzing water to produce hydrogen according to claim 2, characterized in that: The concentration of ZIF8 in deionized water is 0.001-0.1 g / mL.

6. The method for preparing a nickel-doped ruthenium oxide catalyst for electrolyzing water to produce hydrogen according to claim 2, characterized in that: The mass ratio of the ZIF8 to the ruthenium salt is 2-10:1, and the mass ratio of the ruthenium salt to the nickel salt is 5-20:

1.

7. The method for preparing a nickel-doped ruthenium oxide catalyst for electrolyzing water to produce hydrogen according to claim 2, characterized in that: The ruthenium salt is one or more of ruthenium chloride, bis(pentamethylcyclopentene)ruthenium, bis(cyclopentadiene)ruthenium, and (1,5-cyclooctadiene)ruthenium chloride.

8. The method for preparing a nickel-doped ruthenium oxide catalyst for electrolyzing water to produce hydrogen according to claim 2, characterized in that: The nickel salt is one or more of nickel nitrate hexahydrate, nickel chloride hexahydrate, and nickel acetate hexahydrate.

9. The method for preparing a nickel-doped ruthenium oxide catalyst for electrolyzing water to produce hydrogen according to claim 2, characterized in that: The sintering process is carried out at a temperature of 500-900° C., for a time of 2-8 hours, at a heating rate of 3-5° C. / min, and in an air atmosphere.

10. The nickel-doped ruthenium oxide water electrolysis hydrogen production catalyst according to any one of claims 1 to 9 is used in the oxygen evolution reaction at the anode of water electrolysis.

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