Preparation Method and Application of Self-Supported Iron-Manganese Co-Doped Nickel Cobalt Selenide Nanorod Array Catalyst
The nickel-cobalt selenide nanorod array catalyst that supports iron-manganese co-doped co-doped on a foam nickel substrate was prepared by hydrothermal method on a foam nickel substrate, which solved the problems of slow reaction kinetics and scarce reserves of precious metal catalysts in the existing electrocatalytic water decomposition technology, and achieved efficient and low-cost hydrogen production effect of electrolytic water.
Patent Information
- Application Number
- CN202310346039.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-04-03
- Publication Date
- 2025-06-24
- Estimated Expiration
- 2043-04-03
AI Technical Summary
In the existing electrocatalytic water decomposition technology, the kinetics of anode oxygen evolution reaction and cathode hydrogen evolution reaction are slow and require a high voltage, which limits the conversion efficiency of electrolytic water, and the reserves of precious metal catalysts are scarce and expensive, which limits their practical application.
The nickel-cobalt selenide nanorod array catalyst that supports iron-manganese co-doped co-doped nickel-cobalt selenide nanorod array catalyst was prepared on a foam nickel substrate by hydrothermal method. The electronic structure of the catalyst was regulated by heterogeneous elements, increasing the active site and specific surface area, and improving conductivity and stability.
The excellent electrolytic activity and stability of the catalyst is achieved, the electrolytic efficiency is improved, the production cost is reduced, and the industrial application prospects are broad.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of electrocatalytic material preparation, specifically to a preparation method and application of a self-supporting iron-manganese co-doped nickel-cobalt selenide nanorod array catalyst, and the prepared material is used in the technical field of hydrogen production by electrolyzing water. Background Art
[0002] Traditional fossil fuels such as coal, oil, and natural gas are still the main sources of energy. However, the reserves of fossil energy are limited, the energy utilization rate is not high, and it is difficult to meet people's usage requirements. Moreover, fossil fuels are non-renewable energy sources, and their large-scale consumption will lead to serious energy crises and environmental pollution problems. Developing renewable clean energy can effectively alleviate energy crises, reduce the emissions of atmospheric pollutants, and improve the ecological environment, thereby realizing the sustainable development of human society. Solar energy, wind energy, and tidal energy are typical renewable energy sources that can reduce the consumption of fossil fuels. However, due to the constraints of seasonal and regional factors, these energies are uncontrollable and unpredictable in time, thus severely limiting their large-scale applications. Therefore, there is an urgent need to develop energy storage and conversion technologies to make full use of these renewable energy sources.
[0003] In recent years, many advanced energy storage and conversion technologies have developed rapidly, such as metal-ion batteries, metal-air batteries, supercapacitors, photocatalytic hydrogen production, and fuel cells. Hydrogen (H2) has characteristics such as high specific energy density, pollution-free combustion, abundant sources, compressible storage, and convenient transportation, and is considered the "ultimate energy" to replace fossil fuels. Moreover, as an ideal energy storage medium, hydrogen energy can convert unstable solar energy, wind energy, and tidal energy into stable chemical energy. Electrochemical water splitting (OWS) is an important way to obtain hydrogen energy, but its anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction (HER) are slow kinetic reactions, and a relatively high voltage is required to overcome the reaction energy barrier, which severely limits the conversion efficiency of electrolytic water. A large number of studies have shown that the most efficient OER and HER catalysts currently are still noble metal materials such as RuO2 / IrO2 and Pt, but their scarce reserves and high prices lead to very limited prospects for their practical applications. Therefore, rationally designing non-noble metal catalysts with low cost, high performance, and abundant reserves plays a crucial role in the development of hydrogen production technology by electrolyzing water and alleviating energy and environmental problems.
[0004] Transition metals have unpaired electrons and unfilled orbitals, can form empty d electron orbitals for chemisorption bonds, and have diverse adsorption positions. Therefore, they are often used to prepare electrocatalysts. Transition metal selenides have characteristics such as good electrical conductivity, low cost, high activity, and easy preparation, which have attracted extensive attention from researchers. The catalytic active centers of transition metals have adjustable redox properties, making transition metal selenides have excellent electrocatalytic performance. Moreover, the low bandgap and high covalency of transition metal selenides enhance the charge transport characteristics, making them have better electrical conductivity and more active sites than the corresponding oxides. Heteroatom doping can increase active sites and regulate the electronic structure, thereby improving the electrocatalytic activity. Combining with a conductive substrate to construct a self-supporting array structure can improve the electrical conductivity and stability of the catalyst. Therefore, considering the above characteristics, a self-supporting iron-manganese co-doped nickel-cobalt selenide nanorod array catalyst was prepared. This catalyst has excellent electrolytic water activity and stability, and can effectively improve the electrolytic water efficiency. Summary of the Invention
[0005] One of the objectives of the present invention is to provide a preparation method for a self-supporting iron-manganese co-doped nickel-cobalt selenide nanorod array catalyst. Using nickel foam as the growth substrate, a self-supporting iron-manganese co-doped nickel-cobalt selenide nanorod array catalyst was prepared through a hydrothermal method and selenization treatment. Another objective of the present invention is to apply the self-supporting iron-manganese co-doped nickel-cobalt selenide nanorod array catalyst prepared by the above method to hydrogen production by electrolyzing water. Through doping, the electronic structure of nickel-cobalt selenide was effectively regulated. The nanorod array structure increased the catalytic active sites and specific surface area, and the conductive substrate nickel foam improved the electrical conductivity and stability, thereby promoting the improvement of the electrolytic water performance.
[0006] The present invention is realized through the following technical solutions: A preparation method for a self-supporting iron-manganese co-doped nickel-cobalt selenide nanorod array catalyst, including the following steps:
[0007] (1) Nickel nitrate hexahydrate, cobalt nitrate hexahydrate, iron nitrate nonahydrate, manganese nitrate tetrahydrate, urea, and ammonium fluoride were placed in a beaker according to a molar ratio of 1 mmol: 1 - 2 mmol: 0 - 0.3 mmol: 0 - 0.3 mmol: 3 - 10 mmol: 1 - 5 mmol, 20 mL of deionized water was added, and magnetic stirring was carried out at a constant temperature. After stirring evenly, it was placed in a 50 mL high-pressure reaction kettle with pretreated nickel foam, and sufficient hydrothermal reaction was carried out in a blast drying oven. The hydrothermal reaction temperature was 100 - 160 °C, and the heat preservation time was 3 - 12 h;
[0008] (2) Wait for the high-pressure reaction kettle to cool naturally, take out the reaction product, wash it several times with absolute ethanol and deionized water in sequence, and put it into a vacuum drying oven to dry, to obtain the iron-manganese co-doped precursor material;
[0009] (3) Place selenium powder and sodium hydroxide in a beaker according to a mass ratio of 0.1 - 0.2 g : 1.5 - 5 g, add 20 mL of deionized water, stir magnetically at a constant temperature, and after stirring evenly, place it in a high-pressure reaction kettle, and carry out a full hydrothermal reaction in a blast drying oven. The hydrothermal reaction temperature is 160 - 200 °C, and the heat preservation time is 6 - 24 h to obtain an alkali solution containing selenium.
[0010] (4) Put the prepared precursor and the selenium-containing alkali solution into a high-pressure reaction kettle, and carry out a full hydrothermal reaction in a blast drying oven. The hydrothermal reaction temperature is 100 - 160 °C, and the heat preservation time is 3 - 12 h.
[0011] (5) Wait for the high-pressure reaction kettle to cool naturally, take out the reaction product, wash it several times with absolute ethanol and deionized water in turn, and put it into a vacuum drying oven to dry to obtain the self-supporting iron and manganese co-doped nickel cobalt selenide nanorod array catalyst.
[0012] The nickel foam described in step (1) is ultrasonically treated with 1 mol / L hydrochloric acid, absolute ethanol and deionized water for 10 min in turn.
[0013] The magnetic stirring time is 10 - 30 min, and the stirring speed is 650 - 850 r / min.
[0014] The hydrothermal reaction products are washed 3 times with absolute ethanol and deionized water in turn.
[0015] The drying temperature of the washed hydrothermal reaction product is 60 °C, and the heat preservation time is 12 h.
[0016] Nickel nitrate hexahydrate, cobalt nitrate hexahydrate, iron nitrate nonahydrate, manganese nitrate tetrahydrate, urea, ammonium fluoride, selenium powder, sodium hydroxide, absolute ethanol, and potassium hydroxide used in the present invention are all of analytical grade and are purchased from Shanghai Macklin Biochemical Co., Ltd.
[0017] The beneficial effects of the present invention:
[0018] 1. The present invention directly prepares a self-supporting iron and manganese co-doped nickel cobalt selenide catalytic material on a nickel foam substrate by a hydrothermal method, avoiding the use of binders and conductive agents, which is beneficial to simplifying the preparation process and reducing costs.
[0019] 2. The catalyst obtained by this preparation method has a rough nanorod array structure, and a large number of voids and channels are formed between the arrays, which can provide a high specific surface area and rich active sites, thereby improving its apparent activity; hetero-element doping can regulate the electronic structure of the catalyst and optimize the adsorption energy of reaction intermediates, thereby improving its intrinsic activity; by constructing a self-supporting structure with nickel foam as the substrate, its conductivity can be improved and its stability can be enhanced. The catalyst prepared by the present invention can exhibit excellent electrolytic water activity and stability, and has been successfully applied to hydrogen production by electrolytic water.
[0020] 3. This preparation method is simple, low-cost, high-yield, and easy to prepare in batches, with broad prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is the X-ray diffraction (XRD) pattern of the Fe,Mn-NiCo2Se4 / NF-6 catalyst prepared in Example 1.
[0022] Figure 2 It is the scanning electron microscope (SEM) image of the Fe,Mn-NiCo2Se4 / NF-6 catalyst prepared in Example 1.
[0023] Figure 3 It is the oxygen evolution reaction (OER) polarization curve of the Fe,Mn-NiCo2Se4 / NF-6 catalyst prepared in Example 1.
[0024] Figure 4 It is the hydrogen evolution reaction (HER) polarization curve of the Fe,Mn-NiCo2Se4 / NF-6 catalyst prepared in Example 1.
[0025] Figure 5 It is the overall water splitting (OWS) polarization curve of the Fe,Mn-NiCo2Se4 / NF-6 catalyst prepared in Example 1.
[0026] Figure 6 It is the E-t curve of the overall water splitting (OWS) stability test of the Fe,Mn-NiCo2Se4 / NF-6 catalyst prepared in Example 1. DETAILED DESCRIPTION OF THE INVENTION
[0027] The technical solutions of the present invention will be further described below in conjunction with the drawings and embodiments.
[0028] Example 1
[0029] This example is an instance of the preparation method of the self-supported iron-manganese co-doped nickel-cobalt selenide nanorod array catalyst of the present invention, including the following steps:
[0030] (1) Place 1 mmol of nickel nitrate hexahydrate, 2 mmol of cobalt nitrate hexahydrate, 0.2 mmol of iron nitrate nonahydrate, 0.2 mmol of manganese nitrate tetrahydrate, 5 mmol of urea, and 1 mmol of ammonium fluoride in a beaker, add 20 mL of deionized water and mix to obtain a mixed solution;
[0031] (2) Magnetically stir the obtained mixed solution at a constant temperature for 30 min at a stirring speed of 800 r / min until all the solids are completely dissolved and evenly mixed;
[0032] (3) Then place the uniformly mixed solution in a high-pressure reaction kettle containing pretreated nickel foam, and put it into a forced-air drying oven to react fully at 120 °C for 8 h;
[0033] (4) Wait for the high-pressure reaction kettle to cool naturally, take out the reaction product, wash it 3 times with absolute ethanol and deionized water in sequence, put it into a vacuum drying oven at 60 °C and dry it for 12 h to obtain a precursor sample of iron and manganese co-doped;
[0034] (5) Place 0.15 g of selenium powder and 2 g of sodium hydroxide in a beaker, add 20 mL of deionized water, stir magnetically at a constant temperature for 30 min with a stirring speed of 800 r / min. After stirring evenly, place it in a high-pressure reaction kettle and put it into a forced-air drying oven to react fully at 180 °C for 12 h to obtain a selenium-containing alkaline solution;
[0035] (6) Place the precursor sample and the selenium-containing alkaline solution in a high-pressure reaction kettle, and put it into a forced-air drying oven to react fully at 120 °C for 6 h. Wait for the high-pressure reaction kettle to cool naturally, take out the reaction product, wash it 3 times with absolute ethanol and deionized water in sequence, put it into a vacuum drying oven at 60 °C and dry it for 12 h to obtain an iron and manganese co-doped nickel cobalt selenide nanorod array catalyst directly grown on nickel foam. As Figure 1 shown, the XRD diffraction peaks of the prepared nickel cobalt selenide match those of NiCo2Se4 (PDF#04-006-5241), and Figure 2 shown, the morphology of the nickel cobalt selenide is a typical nanorod array structure. Since the selenization reaction time is 6 h, the product obtained in this example is denoted as Fe,Mn-NiCo2Se4 / NF-6, and the following is similar.
[0036] Example 2
[0037] This example is a comparative example of the preparation method of the self-supporting iron and manganese co-doped nickel cobalt selenide nanorod array catalyst of the present invention, without doping, and includes the following steps:
[0038] (1) Place 1 mmol of nickel nitrate hexahydrate, 2 mmol of cobalt nitrate hexahydrate, 5 mmol of urea and 1 mmol of ammonium fluoride in a beaker, add 20 mL of deionized water for mixing to obtain a mixed solution;
[0039] (2) Stir the obtained mixed solution magnetically at a constant temperature for 30 min with a stirring speed of 800 r / min until all the solids are dissolved evenly;
[0040] (3) Then place the uniformly mixed solution in a high-pressure reaction kettle containing pretreated nickel foam, and put it into a forced-air drying oven to react fully at 120 °C for 8 h;
[0041] (4) Wait for the high-pressure reactor to cool naturally, take out the reaction product, wash it 3 times with anhydrous ethanol and deionized water in sequence, put it into a vacuum drying oven at 60 °C and dry it for 12 h to obtain an undoped precursor sample;
[0042] (5) Place 0.15 g of selenium powder and 2 g of sodium hydroxide in a beaker, add 20 mL of deionized water, stir magnetically at a constant temperature for 30 min with a stirring speed of 800 r / min. After stirring evenly, place it in a high-pressure reactor and put it into a blast drying oven to react fully at 180 °C for 12 h to obtain a selenium-containing alkaline solution;
[0043] (6) Place the precursor sample and the selenium-containing alkaline solution in a high-pressure reactor, put it into a blast drying oven and react fully at 120 °C for 6 h. Wait for the high-pressure reactor to cool naturally, take out the reaction product, wash it 3 times with anhydrous ethanol and deionized water in sequence, put it into a vacuum drying oven at 60 °C and dry it for 12 h to obtain a nickel cobalt selenide nanorod array catalyst directly grown on nickel foam. Due to no doping, the product obtained in this example is denoted as NiCo2Se4 / NF-6.
[0044] Example 3
[0045] This example is another comparative example of the preparation method of the self-supporting iron and manganese co-doped nickel cobalt selenide nanorod array catalyst described in the present invention, only doped with Fe, and includes the following steps:
[0046] (1) Place 1 mmol of nickel nitrate hexahydrate, 2 mmol of cobalt nitrate hexahydrate, 0.2 mmol of iron nitrate nonahydrate, 5 mmol of urea and 1 mmol of ammonium fluoride in a beaker, add 20 mL of deionized water for mixing to obtain a mixed solution;
[0047] (2) Stir the obtained mixed solution magnetically at a constant temperature for 30 min with a stirring speed of 800 r / min until all the solids are dissolved evenly;
[0048] (3) Then place the uniformly mixed solution in a high-pressure reactor containing pretreated nickel foam, put it into a blast drying oven and react fully at 120 °C for 8 h;
[0049] (4) Wait for the high-pressure reactor to cool naturally, take out the reaction product, wash it 3 times with anhydrous ethanol and deionized water in sequence, put it into a vacuum drying oven at 60 °C and dry it for 12 h to obtain an iron-doped precursor sample;
[0050] (5) Place 0.15 g of selenium powder and 2 g of sodium hydroxide in a beaker, add 20 mL of deionized water, stir magnetically at a constant temperature for 30 min with a stirring speed of 800 r / min. After stirring evenly, place it in a high-pressure reactor and put it into a blast drying oven to react fully at 180 °C for 12 h to obtain a selenium-containing alkaline solution;
[0051] (6) Place the precursor sample and the selenium-containing alkali solution in a high-pressure reactor, and put it in a blast drying oven to react fully at 120 °C for 6 h. Wait for the high-pressure reactor to cool naturally, take out the reaction product, wash it 3 times with absolute ethanol and deionized water in sequence, put it in a vacuum drying oven at 60 °C and dry it for 12 h to obtain an iron-doped nickel cobalt selenide nanorod array catalyst directly grown on nickel foam. Since only Fe is doped, the product obtained in this example is denoted as Fe-NiCo2Se4 / NF-6.
[0052] Example 4
[0053] This example is another comparative example of the preparation method of the self-supporting iron and manganese co-doped nickel cobalt selenide nanorod array catalyst described in the present invention. Only Mn is doped, and it includes the following steps:
[0054] (1) Place 1 mmol of nickel nitrate hexahydrate, 2 mmol of cobalt nitrate hexahydrate, 0.2 mmol of manganese nitrate tetrahydrate, 5 mmol of urea and 1 mmol of ammonium fluoride in a beaker, add 20 mL of deionized water and mix to obtain a mixed solution;
[0055] (2) Magnetically stir the obtained mixed solution at a constant temperature for 30 min with a stirring speed of 800 r / min until all the solids are dissolved evenly;
[0056] (3) Then place the uniformly mixed solution in a high-pressure reactor containing pretreated nickel foam, and put it in a blast drying oven to react fully at 120 °C for 8 h;
[0057] (4) Wait for the high-pressure reactor to cool naturally, take out the reaction product, wash it 3 times with absolute ethanol and deionized water in sequence, put it in a vacuum drying oven at 60 °C and dry it for 12 h to obtain a manganese-doped precursor sample;
[0058] (5) Place 0.15 g of selenium powder and 2 g of sodium hydroxide in a beaker, add 20 mL of deionized water, magnetically stir at a constant temperature for 30 min with a stirring speed of 800 r / min, stir evenly, then place it in a high-pressure reactor, and put it in a blast drying oven to react fully at 180 °C for 12 h to obtain a selenium-containing alkali solution;
[0059] (6) Place the precursor sample and the selenium-containing alkali solution in a high-pressure reactor, and put it in a blast drying oven to react fully at 120 °C for 6 h. Wait for the high-pressure reactor to cool naturally, take out the reaction product, wash it 3 times with absolute ethanol and deionized water in sequence, put it in a vacuum drying oven at 60 °C and dry it for 12 h to obtain a manganese-doped nickel cobalt selenide nanorod array catalyst directly grown on nickel foam. Since only Mn is doped, the product obtained in this example is denoted as Mn-NiCo2Se4 / NF-6.
[0060] Example 5
[0061] This example is another instance of the preparation method of the self-supporting iron and manganese co-doped nickel cobalt selenide nanorod array catalyst described in the present invention, and includes the following steps:
[0062] (1) Place 1 mmol of nickel nitrate hexahydrate, 2 mmol of cobalt nitrate hexahydrate, 0.2 mmol of iron nitrate nonahydrate, 0.2 mmol of manganese nitrate tetrahydrate, 5 mmol of urea, and 1 mmol of ammonium fluoride in a beaker, add 20 mL of deionized water for mixing to obtain a mixed solution;
[0063] (2) Magnetically stir the obtained mixed solution at a constant temperature for 30 min at a stirring speed of 800 r / min until all the solids are completely dissolved and evenly mixed;
[0064] (3) Then place the evenly mixed solution in a high-pressure reaction kettle containing pretreated nickel foam, and place it in a blast drying oven to react fully at 120 °C for 8 h;
[0065] (4) Wait for the high-pressure reaction kettle to cool naturally, take out the reaction product, wash it 3 times with absolute ethanol and deionized water in sequence, place it in a vacuum drying oven at 60 °C and dry it for 12 h to obtain an iron and manganese co-doped precursor sample;
[0066] (5) Place 0.15 g of selenium powder and 2 g of sodium hydroxide in a beaker, add 20 mL of deionized water, magnetically stir at a constant temperature for 30 min at a stirring speed of 800 r / min. After stirring evenly, place it in a high-pressure reaction kettle and place it in a blast drying oven to react fully at 180 °C for 12 h to obtain a selenium-containing alkaline solution.
[0067] (6) Place the precursor sample and the selenium-containing alkaline solution in a high-pressure reaction kettle, and place it in a blast drying oven to react fully at 120 °C for 3 h. Wait for the high-pressure reaction kettle to cool naturally, take out the reaction product, wash it 3 times with absolute ethanol and deionized water in sequence, place it in a vacuum drying oven at 60 °C and dry it for 12 h to obtain an iron and manganese co-doped nickel cobalt selenide nanorod array catalyst directly grown on nickel foam. Since the selenization reaction time is 3 h, the product obtained in this example is denoted as Fe,Mn-NiCo2Se4 / NF-3.
[0068] Example 6
[0069] This example is yet another instance of the preparation method of the self-supporting iron and manganese co-doped nickel cobalt selenide nanorod array catalyst with different selenization reaction times, and includes the following steps:
[0070] (1) Place 1 mmol of nickel nitrate hexahydrate, 2 mmol of cobalt nitrate hexahydrate, 0.2 mmol of iron nitrate nonahydrate, 0.2 mmol of manganese nitrate tetrahydrate, 5 mmol of urea, and 1 mmol of ammonium fluoride in a beaker, add 20 mL of deionized water for mixing to obtain a mixed solution;
[0071] (2) Keep the obtained mixed solution under constant temperature with magnetic stirring for 30 min at a stirring speed of 800 r / min until all the solids are completely dissolved and evenly mixed;
[0072] (3) Then place the evenly mixed solution in a high-pressure reaction kettle containing pretreated nickel foam, and put it into a blast drying oven to react fully at 120 °C for 8 h;
[0073] (4) Wait for the high-pressure reaction kettle to cool naturally, take out the reaction product, wash it 3 times successively with absolute ethanol and deionized water, put it into a vacuum drying oven at 60 °C and dry it for 12 h to obtain a precursor sample of iron and manganese co-doped;
[0074] (5) Place 0.15 g of selenium powder and 2 g of sodium hydroxide in a beaker, add 20 mL of deionized water, stir magnetically at a constant temperature for 30 min at a stirring speed of 800 r / min. After stirring evenly, place it in a high-pressure reaction kettle and put it into a blast drying oven to react fully at 180 °C for 12 h to obtain a selenium-containing alkaline solution.
[0075] (6) Place the precursor sample and the selenium-containing alkaline solution in a high-pressure reaction kettle, and put it into a blast drying oven to react fully at 120 °C for 9 h. Wait for the high-pressure reaction kettle to cool naturally, take out the reaction product, wash it 3 times successively with absolute ethanol and deionized water, put it into a vacuum drying oven at 60 °C and dry it for 12 h to obtain an iron and manganese co-doped nickel cobalt selenide nanorod array catalyst directly grown on nickel foam. Since the selenization reaction time is 9 h, the product obtained in this example is denoted as Fe,Mn-NiCo2Se4 / NF-9.
[0076] Example 7
[0077] This example is the 7th example of the preparation method of the self-supporting iron and manganese co-doped nickel cobalt selenide nanorod array catalyst described in the present invention. The selenization reaction time is different, and it includes the following steps:
[0078] (1) Place 1 mmol of nickel nitrate hexahydrate, 2 mmol of cobalt nitrate hexahydrate, 0.2 mmol of iron nitrate nonahydrate, 0.2 mmol of manganese nitrate tetrahydrate, 5 mmol of urea and 1 mmol of ammonium fluoride in a beaker, add 20 mL of deionized water for mixing to obtain a mixed solution;
[0079] (2) Keep the obtained mixed solution under constant temperature with magnetic stirring for 30 min at a stirring speed of 800 r / min until all the solids are completely dissolved and evenly mixed;
[0080] (3) Then place the evenly mixed solution in a high-pressure reaction kettle containing pretreated nickel foam, and put it into a blast drying oven to react fully at 120 °C for 8 h;
[0081] (4) Wait for the high-pressure reactor to cool naturally, take out the reaction product, wash it 3 times successively with absolute ethanol and deionized water, put it into a vacuum drying oven at 60 °C and dry it for 12 h to obtain an iron-manganese co-doped precursor sample;
[0082] (5) Place 0.15 g of selenium powder and 2 g of sodium hydroxide in a beaker, add 20 mL of deionized water, stir magnetically at a constant temperature for 30 min, with a stirring speed of 800 r / min. After stirring evenly, place it in a high-pressure reactor and put it into a blast drying oven to react fully at 180 °C for 12 h to obtain a selenium-containing alkaline solution;
[0083] (6) Place the precursor sample and the selenium-containing alkaline solution in a high-pressure reactor, put it into a blast drying oven and react fully at 120 °C for 12 h. Wait for the high-pressure reactor to cool naturally, take out the reaction product, wash it 3 times successively with absolute ethanol and deionized water, put it into a vacuum drying oven at 60 °C and dry it for 12 h to obtain an iron-manganese co-doped nickel-cobalt selenide nanorod array catalyst directly grown on nickel foam. Since the selenization reaction time is 12 h, the product obtained in this example is denoted as Fe,Mn-NiCo2Se4 / NF-12.
[0084] Table 1 Performance test results of nickel-cobalt selenide nanorod array catalysts obtained under different test conditions
[0085]
[0086] As can be seen from the results in Table 1, the electrocatalytic performance of the nickel-cobalt selenide prepared in the present invention is related to factors such as element doping and hydrothermal reaction time. The self-supporting nickel-cobalt selenide nanorod array catalysts prepared by this method all exhibit excellent oxygen evolution, hydrogen evolution and water electrolysis performances. By element doping, the electronic structure of the catalyst can be regulated and the active sites can be increased, further improving the water electrolysis performance of the catalyst. In addition, a reasonable reaction time can obtain materials with better morphology, structure and performance. Therefore, the Fe,Mn-NiCo2Se4 / NF-6 nanorod array catalyst described in Example 1 has better oxygen evolution, hydrogen evolution and water electrolysis activities ( Figures 3 - 5 ), and also exhibits excellent water electrolysis stability ( Figure 6 ), and can be applied to efficient water electrolysis for hydrogen production, with broad application prospects.
[0087] Evaluation of the electrocatalytic activity and stability of the catalysts prepared in the present invention: Using an electrochemical workstation, the polarization curves of each catalyst material are scanned by cyclic voltammetry and linear voltammetry to analyze the electrocatalytic activity performances such as the onset potential, overpotential at a specific current density, Tafel slope, etc. The chronopotentiometry electrochemical method is used to test the stability of the Fe,Mn-NiCo2Se4 / NF-6 nanorod array catalyst material.
Claims
1. Preparation method of self-supporting iron-manganese co-doped nickel cobalt selenide nanorod array catalyst, characterized in that It includes the following steps: (1) Nickel nitrate hexahydrate, cobalt nitrate hexahydrate, iron nitrate nonahydrate, manganese nitrate tetrahydrate, urea and ammonium fluoride are placed in a beaker according to the molar ratio of 1 mmol: 1 - 2 mmol: 0 - 0.3 mmol: 0 - 0.3 mmol: 3 - 10 mmol: 1 - 5 mmol. Add 20 mL of deionized water, stir magnetically at a constant temperature, and after stirring evenly, place it in a 50 mL high-pressure reaction kettle with pretreated nickel foam, and carry out a full hydrothermal reaction in a blast drying oven. The hydrothermal reaction temperature is 100 - 160 °C, and the heat preservation time is 3 - 12 h; (2) Wait for the high-pressure reaction kettle to cool naturally, take out the reaction product, wash it several times with absolute ethanol and deionized water in turn, and put it into a vacuum drying oven to dry to obtain the iron-manganese co-doped precursor material; (3) Selenium powder and sodium hydroxide are placed in a beaker according to the mass ratio of 0.1 - 0.2 g: 1.5 - 5 g. Add 20 mL of deionized water, stir magnetically at a constant temperature, and after stirring evenly, place it in a high-pressure reaction kettle, and carry out a full hydrothermal reaction in a blast drying oven. The hydrothermal reaction temperature is 160 - 200 °C, and the heat preservation time is 6 - 24 h to obtain a selenium-containing alkaline solution; (4) Put the prepared precursor and the selenium-containing alkaline solution into a high-pressure reaction kettle, and carry out a full hydrothermal reaction in a blast drying oven. The hydrothermal reaction temperature is 100 - 160 °C, and the heat preservation time is 3 - 12 h; (5) Wait for the high-pressure reaction kettle to cool naturally, take out the reaction product, wash it several times with absolute ethanol and deionized water in turn, and put it into a vacuum drying oven to dry to obtain the self-supporting iron-manganese co-doped nickel cobalt selenide nanorod array catalyst.
2. The preparation method of the self-supporting iron-manganese co-doped nickel-cobalt selenide nanorod array catalyst according to claim 1, characterized in that, The nickel foam in step (1) is ultrasonically treated with 1 mol / L hydrochloric acid, absolute ethanol and deionized water for 10 min in turn.
3. The preparation method of the self-supporting iron-manganese co-doped nickel cobalt selenide nanorod array catalyst according to claim 1, characterized in that, The magnetic stirring time is 10 - 30 min, and the stirring speed is 650 - 850 r / min.
4. The preparation method of the self-supporting iron-manganese co-doped nickel-cobalt selenide nanorod array catalyst according to claim 1, wherein, The hydrothermal reaction products are washed 3 times with absolute ethanol and deionized water in turn.
5. The preparation method of the self-supporting iron-manganese co-doped nickel cobalt selenide nanorod array catalyst according to claim 1, wherein, The drying temperature of the washed hydrothermal reaction product is 60 °C, and the heat preservation time is 12 h.