Ni3S4-coated Co9S8-coated NC electrocatalyst as well as preparation method and application thereof
By preparing Ni3S4@Co9S8@NC electrocatalyst composed of heterojunction of nickel-cobalt sulfide and nitrogen-doped carbon, the high cost of precious metal catalysts and the structural design difficulties of non-precious metal materials are solved, and efficient and stable hydrogen production performance of electrolytic water is achieved.
Patent Information
- Application Number
- CN202311471310.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-07
- Publication Date
- 2025-07-22
AI Technical Summary
In the prior art, the high cost and limited reserves of precious metal catalysts limit the practical application of electrolyzed hydrogen production, and the structural design of traditional non-precious metal materials is difficult to achieve efficient catalytic activity and stability.
The Ni3S4@Co9S8@NC electrocatalyst composed of nickel-cobalt sulfide heterojunction and nitrogen-doped carbon improves catalytic activity through unique morphology and interfacial charge redistribution.
Under alkaline conditions, the Ni3S4@Co9S8@NC electrode only needs an overpotential of 138 millivolts to achieve a current density of 10 mA/cm2, and the performance has no significant attenuation for 20 hours, showing excellent electrocatalytic performance and stability.
Smart Images
Figure CN120350397A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of synthesis of nanomaterials and their electrocatalytic applications, and in particular to a hollow Ni3S4@Co9S8@NC electrocatalyst, a preparation method thereof, and an application thereof. Background Art
[0002] In order to address the global energy crisis and environmental pollution problems and achieve the goal of "carbon neutrality", clean and sustainable hydrogen energy, as a key alternative energy source, is being widely studied and concerned. As an important method for producing high-purity hydrogen without by-products, electrocatalytic water splitting technology has great potential.
[0003] Traditionally, noble metals such as platinum, iridium, and ruthenium have been widely used as catalysts for hydrogen evolution and oxygen evolution reactions, but their high cost and limited reserves limit their practical applications. In recent years, researchers have extensively explored the possibility of using various non-noble metal materials as electrolytic water catalysts, including transition metal sulfides, phosphides, carbides, nitrides, oxides, selenides, and hydroxides. In particular, transition metal-based sulfides have attracted much attention due to their excellent catalytic properties and good electrical conductivity. However, in order to achieve high catalytic activity and stability, it is crucial to rationally design the structure and morphology of sulfides.
[0004] Metal-organic framework materials (MOFs) have become ideal precursors for preparing these micro / nano structures due to their high specific surface area, combination of various metal / organic ligands, and tunability of structure and composition. However, the controllable preparation of hollow nanomaterials with complex compositions and special morphological structures still faces challenges, and the overcoming of these challenges is crucial for improving the efficiency and sustainability of reactions such as water splitting. Summary of the Invention
[0005] The present application provides a hollow Ni3S4@Co9S8@NC electrocatalyst, a preparation method thereof, and an application thereof. The catalyst has a unique morphology, and constructing a sulfide heterojunction interface can induce interfacial charge redistribution, further enhancing the catalytic activity.
[0006] The first aspect of the present application is to provide a preparation method of a Ni3S4@Co9S8@NC electrocatalyst, and the steps include:
[0007] A nickel source, a cobalt source, and a surfactant are dispersed in a solvent together. After heating, the solid is collected;
[0008] The collected solid is reacted with a sulfur source to sulfide at least part of Ni and Co to obtain an intermediate;
[0009] The intermediate is annealed, and Ni and Co are respectively transformed into highly crystalline Ni3S4 and Co9S8, while the organic components in the intermediate are transformed into nitrogen-doped carbon to form the Ni3S4@Co9S8@NC electrocatalyst.
[0010] In a preferred embodiment, the nickel source may be a nickel salt, such as an inorganic acid salt or an organic acid salt, for example, selected from nickel nitrate, nickel carbonate, nickel chloride, nickel bromide, nickel sulfate, nickel acetate, nickel formate, nickel citrate, etc.
[0011] In a preferred embodiment, the cobalt source may be a cobalt salt, such as an inorganic acid salt or an organic acid salt, for example, selected from cobalt nitrate, cobalt chloride, cobalt bromide, cobalt sulfate, cobalt phosphate, cobalt carbonate, cobalt acetate, cobalt formate, cobalt oxalate, cobalt sulfamate, cobalt acetylacetonate, etc. Without special instructions, the cobalt may be one or more of Co(II) and Co(III).
[0012] In a preferred embodiment, the solvent may be selected from water, alcohols, esters, ethers, ketones, aldehydes, carboxylic acids, hydrocarbons, sulfones, nitriles, etc., for example, selected from water, methanol, ethanol, propanol, isopropanol, ethylene glycol, ethyl acetate, butyl acetate, acetone, diethyl ether, petroleum ether, dimethyl sulfoxide, acetonitrile, halogenated hydrocarbons, aromatic hydrocarbons, tetrahydrofuran, etc.
[0013] In a preferred embodiment, the nickel source, the cobalt source and the surfactant are heated to 50-150 °C, preferably heated to 60-120 °C, more preferably 70-100 °C, and even more preferably 80-90 °C.
[0014] In a preferred embodiment, the heating time of the nickel source, the cobalt source and the surfactant together is preferably at least 15 minutes, more preferably at least 30 minutes, more preferably 0.5-12 hours, more preferably 1-10 hours, more preferably 2-9 hours, more preferably 3-7 hours, and even more preferably 4-6 hours.
[0015] In a preferred embodiment, the molar ratio of Ni to Co of the nickel source to the cobalt source is preferably 1:(0.5-1.5), more preferably 1:(0.7-1.2), such as 1:0.8, 1:1, 1:1, etc.
[0016] In a preferred embodiment, the surfactant may be selected from one of polyvinylpyrrolidone, cetyltrimethylammonium bromide, sodium benzenesulfonate, and benzenesulfonic acid.
[0017] In a preferred embodiment, the molar volume concentration of the nickel source in the solvent (the number of moles of Ni per ml of solution) is preferably (1-5)×10 -5 mol / ml, more preferably (1.5-4)×10-5 mol / ml, more preferably (2 - 3)×10 -5 mol / ml.
[0018] In a preferred embodiment, the mass - volume concentration of the surfactant in the volume (weight of A in grams per ml of solution) is preferably 0.001 - 1 g / ml, more preferably 0.005 - 0.8 g / ml, more preferably 0.01 - 0.5 g / ml, and more preferably 0.1 - 0.3 g / ml.
[0019] In a preferred embodiment, the collected solid and the sulfur source are dispersed in a second solvent and reacted. Preferably, the second solvent can be selected from water, alcohols, esters, ethers, ketones, aldehydes, carboxylic acids, hydrocarbons, sulfones, nitriles, etc. For example, it can be selected from water, methanol, ethanol, propanol, isopropanol, ethylene glycol, ethyl acetate, butyl acetate, acetone, diethyl ether, petroleum ether, dimethyl sulfoxide, acetonitrile, halogenated hydrocarbons, aromatic hydrocarbons, tetrahydrofuran, etc.
[0020] In a preferred embodiment, the sulfur source is a compound capable of providing S 2- such as hydrosulfates (i.e., sulfides). More preferably, it can be selected from ammonium sulfide, sodium sulfide, potassium sulfide, iron sulfide, ferrous sulfide, copper sulfide, magnesium sulfide, zinc sulfide, calcium sulfide, mercury sulfide, cadmium sulfide, lead sulfide, barium sulfide, etc.
[0021] More preferably, the sulfur source can be a compound that can be dissolved in the second solvent, or it can be added to the second solvent after being dissolved in a third solvent. Preferably, the third solvent can be selected from water, alcohols, esters, ethers, ketones, aldehydes, carboxylic acids, hydrocarbons, sulfones, nitriles, etc. For example, it can be selected from water, methanol, ethanol, propanol, isopropanol, ethylene glycol, ethyl acetate, butyl acetate, acetone, diethyl ether, petroleum ether, dimethyl sulfoxide, acetonitrile, halogenated hydrocarbons, aromatic hydrocarbons, tetrahydrofuran, etc.
[0022] In a preferred embodiment, the molar number of S is preferably greater than or equal to the sum of the molar numbers of Ni and Co.
[0023] In a preferred embodiment, the reaction time of the collected solid and the sulfur source is at least 1 minute, more preferably at least 2 minutes, more preferably at least 5 minutes, more preferably 10 - 60 minutes, more preferably 20 - 45 minutes, and more preferably 30 - 40 minutes.
[0024] In a preferred embodiment, the intermediate is annealed under an inert gas condition. The inert gas is preferably selected from one or more of nitrogen, argon, and hydrogen.
[0025] In a preferred embodiment, during the annealing process of the intermediate, the heating temperature is preferably 50 - 800 °C, more preferably 80 - 600 °C, more preferably 100 - 500 °C, more preferably 150 - 450 °C, more preferably 200 - 400 °C, more preferably 250 - 350 °C.
[0026] In a preferred embodiment, during the annealing process of the intermediate, the heating time is preferably at least 5 minutes, more preferably at least 10 minutes, more preferably at least 15 minutes, more preferably 0.5 - 6 hours, more preferably 1 - 4 hours.
[0027] In a preferred embodiment, during the annealing process of the intermediate, the heating and cooling rates are independently selected from 1 - 10 °C / min, more preferably 3 - 8 °C / min, more preferably 5 - 7 °C / min.
[0028] The second aspect of the present application is to provide a Ni3S4@Co9S8@NC electrocatalyst prepared by the preparation method described in the first aspect of the present application. Preferably, when used as a catalyst for the hydrogen evolution reaction, an overpotential of ≤150 mV can achieve a current density of 10 mA / cm². More preferably, an overpotential of ≤145 mV can achieve a current density of 10 mA / cm². More preferably, an overpotential of ≤140 mV can achieve a current density of 10 mA / cm².
[0029] The third aspect of the present application is to provide an application of the Ni3S4@Co9S8@NC electrocatalyst. The Ni3S4@Co9S8@NC electrocatalyst is used in an electrocatalytic method and / or an electrocatalytic device, preferably as a catalyst for the hydrogen evolution reaction.
[0030] Preferably, the Ni3S4@Co9S8@NC electrocatalyst is used to prepare an electrolysis electrode. More preferably, the electrolysis is the electrolysis of water, and more preferably the electrolysis of alkaline water.
[0031] When the catalyst synthesized in the present application is tested for water electrolysis under alkaline conditions, Ni3S4@Co9S8@NC exhibits good electrocatalytic performance. When used as a catalyst for the hydrogen evolution reaction, the Ni3S4@Co9S8@NC electrode only requires an overpotential of 138 mV to achieve a current density of 10 mA / cm², and the performance shows no obvious attenuation after 20 hours.
[0032] The Ni3S4@Co9S8@NC of this application has excellent electrocatalytic activity, which can be attributed to the following advantages: 1) The unique hollow structure provides a large specific surface area and exposes a large number of accessible active sites; 2) After annealing, the surface is interconnected to form a Ni3S4 and Co9S8 heterojunction, improving the electron transfer efficiency in the interfacial region; 3) The pores formed by the particles are beneficial to the immersion of the electrolyte and the escape of gas; 4) Nitrogen-doped carbon further improves the conductivity of the material and enhances the charge transfer efficiency. Due to the synergistic regulation of the unique hollow structure, the heterointerfacial composition of nickel / cobalt sulfide, and the nitrogen-doped carbon component, it jointly promotes the excellent electrocatalytic water splitting activity and long-term stability of Ni3S4@Co9S8@NC. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments and descriptions thereof of this application are used to explain this application and do not constitute an improper limitation of this application. In the drawings:
[0034] Figure 1 is the XRD spectrum of the Ni3S4@Co9S8@NC electrocatalyst of this application;
[0035] Figure 2 is the TEM image of the Ni3S4@Co9S8@NC electrocatalyst of this application;
[0036] Figure 3 is the HER polarization curve of the Ni3S4@Co9S8@NC electrocatalyst of this application;
[0037] Figure 4 is the chronopotentiometry curve of the Ni3S4@Co9S8@NC electrocatalyst of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0038] This application provides a Ni3S4@Co9S8@NC electrocatalyst, its preparation method and application. To make the purpose, technical solution and effects of this application clearer and more definite, the following further describes this application in detail with reference to the drawings and by way of examples. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.
[0039] It should be noted that the terms "first", "second", etc. in the description, claims and the above-mentioned drawings of this application are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.
[0040] The raw materials used in the embodiments of this application are all commercially available analytical pure products and have not been further purified.
[0041] The phase of the material prepared in this application was characterized by an XRD-D / MAX2200V PV type X-ray diffractometer. Test conditions: using a Cu target, the radiation source is Kα ray, in the scanning range of 2θ = 5° - 80°, and the sample was scanned and tested at a scanning rate of 8° / minute.
[0042] The microstructure of the material prepared in this application was studied by a Japanese JEM-2100CX transmission electron microscope and a Japanese JEOL JEM-2100F high-resolution transmission electron microscope for the catalyst.
[0043] Example 1
[0044] 1. Preparation of Ni-Co Nanoprisms
[0045] (1) Weigh 1.3 grams of nickel acetate tetrahydrate and 1.3 grams of cobalt acetate tetrahydrate, ultrasonically disperse them in 200 milliliters of absolute ethanol, and then add 3.0 grams of polyvinylpyrrolidone (PVP) under stirring, and stir at room temperature for 30 minutes.
[0046] (2) Transfer this mixed solution to a 200-milliliter round-bottom flask, place it in an oil bath at 85 degrees Celsius and reflux for 4 hours.
[0047] (3) After cooling to room temperature, centrifuge the product to remove the supernatant, add absolute ethanol for washing, and then place it in a vacuum drying oven at 60 degrees Celsius for drying for 12 hours. Obtain the Ni-Co nanopyramid precursor ( NiCo-prisms ).
[0048] 2. Preparation of Ni-Co-S / NiCo-prisms Precursors
[0049] 60 mg of the above-prepared Ni-Co nanopyramid precursor was ultrasonically dispersed in 60 mL of ethanol. Subsequently, 0.5 mL of aqueous ammonium sulfide solution was slowly added dropwise under stirring. After stirring for 30 minutes, the supernatant of the product was removed by centrifugation, and the product was washed three times with deionized water and absolute ethanol respectively, and then dried in a vacuum drying oven at 60 °C for 12 hours.
[0050] 3. Preparation of Ni3S4@Co9S8@NC
[0051] 30 mg of the above sample was weighed into a porcelain boat, covered with a glass slide and placed into a tubular furnace. Under N2 protection, it was heated to 350 °C at a heating rate of 2 °C per minute and annealed for 2 hours.
[0052] Figure 1 XRD pattern of the prepared Ni3S4@Co9S8@NC electrocatalyst. The diffraction peaks of the Ni3S4@Co9S8@NC electrocatalyst are consistent with the crystal planes, proving the successful synthesis of the Ni3S4@Co9S8@NC electrocatalyst.
[0053] Figure 2 TEM image of the prepared Ni3S4@Co9S8@NC electrocatalyst. The results show that the obtained catalyst has a length of about 800 - 900 nm and a width of about 300 - 400 nm. There is a shell with an obvious thickness on the outer layer of the sample, and at the same time, it is found that there are nanoparticles distributed on the surface of the whole sample, making the surface of the sample rough and uneven.
[0054] This application constructs a novel nanostructured electrocatalyst. Since the nickel-cobalt nanopyramid precursor is soluble in water, it releases metal ions Ni 2+ and Co 2+ in the aqueous solution, while ammonium sulfide will undergo a hydrolysis reaction in the aqueous solution to generate S 2– and OH – . During this process, a layer of Ni-Co-S precipitate will be formed on the surface of the precursor first. At the same time, due to the size difference between the cation and anion, the internal and external diffusion rates are different, thus forming a unique hollow structure.
[0055] Comparative Example 1
[0056] (1) 1.3 g of nickel acetate tetrahydrate (Ni(CH3COOH)2·4H2O) and 1.3 g of cobalt acetate tetrahydrate (Co(CH3COOH)2·4H2O) were weighed and ultrasonically dispersed in 200 mL of absolute ethanol. Subsequently, 3.0 g of polyvinylpyrrolidone (PVP) was added under stirring, and stirred at room temperature for 30 minutes.
[0057] (2) This mixed solution was transferred to a 200 mL round-bottom flask and placed in an oil bath at 85 °C for reflux condensation for 4 hours.
[0058] (3) After cooling to room temperature, the product was centrifuged to remove the supernatant, washed with anhydrous ethanol, and then dried in a vacuum drying oven at 60 °C for 12 hours. Ni-Co nanoplisms were obtained.
[0059] Comparative Example 2
[0060] (1) Weigh 1.3 g of nickel acetate tetrahydrate (Ni(CH3COOH)2·4H2O) and 1.3 g of cobalt acetate tetrahydrate (Co(CH3COOH)2·4H2O), ultrasonically disperse them in 200 mL of anhydrous ethanol, and then add 3.0 g of polyvinylpyrrolidone (PVP) under stirring. Stir at room temperature for 30 minutes.
[0061] (2) Transfer this mixed solution to a 200 mL round-bottom flask and place it in an oil bath at 85 °C for reflux condensation for 4 hours.
[0062] (3) After cooling to room temperature, the product was centrifuged to remove the supernatant, washed with anhydrous ethanol, and then dried in a vacuum drying oven at 60 °C for 12 hours.
[0063] (4) Take 60 mg of the Ni-Co nanoplism precursor prepared above, ultrasonically disperse it in 60 mL of ethanol, and then slowly add 0.5 mL of ammonium sulfide aqueous solution dropwise under stirring. After stirring for 30 minutes, the product was centrifuged to remove the supernatant, washed 3 times with deionized water and anhydrous ethanol respectively, and dried in a vacuum drying oven at 60 °C for 12 hours. Ni-Co-S precursor was obtained.
[0064] Performance detection of the electrocatalytic applications of the products obtained in Example 1 and Comparative Examples 1-2:
[0065] Preparation of KOH Electrolyte
[0066] Dissolve 5.6 g of KOH in 50 mL of ultrapure water. After the KOH solution is completely dissolved and cooled, make up the volume to 100 mL in a volumetric flask.
[0067] Preparation of Working Electrode
[0068] First, mix 5 mg of the electrocatalyst of Example 1 or Comparative Example 1 or 2, 330 μL of deionized water, 110 μL of anhydrous ethanol, and 40 μL of Nafion, and then perform ultrasonic treatment to obtain a homogeneous mixture. Then, use a pipette to transfer 100 μL of the above mixture and evenly drop it on the acid-treated nickel foam, and dry it at room temperature.
[0069] Activation Treatment of Electrocatalyst
[0070] (1) The test was carried out using a three - electrode system. A CHI 660E electrochemical workstation produced by Shanghai Chenhua Instrument Co., Ltd. was used. The working electrode was a graphite rod electrode, the reference electrode was a Hg / HgO electrode, and the electrolyte was the above - mentioned KOH electrolyte;
[0071] (2) Electrode activation: The electrode was activated by cyclic voltammetry to reach a stable state.
[0072] Linear Sweep Voltammetry (LSV) Test
[0073] Linear sweep voltammetry was used to test the hydrogen evolution and oxygen evolution over - potentials of the electrode in alkaline solution. Among them, the HER test range was - 0.6 - 0 V (vs. RHE), and the scan rate was 5 mV / s (with automatic IR compensation at a 90% compensation level). All potentials were calibrated according to the reversible hydrogen electrode RHE, and the formula was: E(vs. RHE)=E(vs. Hg / HgO)+0.098 + 0.059×pH.
[0074] The hydrogen evolution catalytic performance of the electrocatalyst of this application was measured using cyclic voltammetry under alkaline conditions. The results are as Figure 3 shown. Ni3S4@Co9S8@NC has the best HER performance. At a current density of 10 mA / cm³, the over - potential is only 138 mV, far lower than that of the Ni - Co nanopyramid (188 mV) and the Ni - Co - S precursor (161 mV) in Comparative Example 1. This indicates that the Ni3S4@Co9S8@NC electrocatalyst has excellent HER catalytic activity.
[0075] The Ni3S4@Co9S8@NC sample provides easily accessible active sites for the electrocatalytic reaction process due to its unique hollow structure, and the modification of the nitrogen - carbon hetero - carbon component improves the conductivity of the material, ultimately enabling the material to exhibit good catalytic performance. The stability test results are as Figure 4 shown. At a constant current of 10 mA / cm³, the fluctuation within 20 hours can be ignored, indicating that Ni3S4@Co9S8@NC has good stability in HER.
[0076] Example 2
[0077] 1. Preparation of Ni-Co Nanoprisms
[0078] (1) Weigh 2.5 g of nickel acetate tetrahydrate and 5 g of cobalt acetate tetrahydrate, ultrasonically disperse them in 300 mL of absolute ethanol, and then add 4.0 g of polyvinylpyrrolidone (PVP) under stirring. Stir at room temperature for 50 minutes.
[0079] (2) Transfer this mixed solution to a 200 - mL round - bottom flask and place it in an oil bath at 85 °C for reflux condensation for 4 hours.
[0080] (3) After cooling to room temperature, the product was centrifuged to remove the supernatant, washed with absolute ethanol, and then dried in a vacuum drying oven at 60 °C for 12 hours. The Ni-Co nanopyramid precursor was obtained.
[0081] 2. Preparation of Ni-Co-S / NiCo-prisms Precursors
[0082] 60 mg of the above-prepared Ni-Co nanopyramid precursor was ultrasonically dispersed in 60 mL of ethanol. Subsequently, 0.5 mL of aqueous ammonium sulfide solution was slowly added dropwise under stirring. After stirring for 30 minutes, the product was centrifuged to remove the supernatant, washed three times with deionized water and absolute ethanol respectively, and dried in a vacuum drying oven at 60 °C for 12 hours.
[0083] 3. Preparation of Ni3S4@Co9S8@NC
[0084] 30 mg of the above sample was weighed into a porcelain boat, covered with a glass slide and placed into a tube furnace. Under the protection of N2, it was heated to 350 °C at a heating rate of 2 °C per minute and annealed for 2 hours.
[0085] At a current density of 10 mA / cm³, the overpotential was 148 mV.
[0086] Example 3
[0087] 1. Preparation of Ni-Co Nanoprisms
[0088] (1) 1.3 g of nickel acetate tetrahydrate and 1.3 g of cobalt acetate tetrahydrate were weighed and ultrasonically dispersed in 200 mL of absolute ethanol. Subsequently, 3.0 g of polyvinylpyrrolidone (PVP) was added under stirring, and stirred at room temperature for 30 minutes.
[0089] (2) This mixed solution was transferred to a 300 mL round-bottom flask and placed in an oil bath at 100 °C for reflux condensation for 5 hours.
[0090] (3) After cooling to room temperature, the product was centrifuged to remove the supernatant, washed with absolute ethanol, and then dried in a vacuum drying oven at 60 °C for 12 hours. The Ni-Co nanopyramid precursor was obtained.
[0091] 2. Preparation of Ni-Co-S / NiCo-prisms Precursors
[0092] 60 mg of the above-prepared Ni-Co nanopyramid precursor was ultrasonically dispersed in 60 mL of ethanol. Subsequently, 0.2 mL of aqueous ammonium sulfide solution was slowly added dropwise under stirring. After stirring for 30 minutes, the product was centrifuged to remove the supernatant, washed three times with deionized water and absolute ethanol respectively, and dried in a vacuum drying oven at 60 °C for 12 hours.
[0093] 3. Preparation of Ni3S4@Co9S8@NC
[0094] Weigh 30 mg of the above sample into a porcelain boat, cover it with a glass slide, place it in a tube furnace, and under the protection of N2, heat it to 350 °C at a heating rate of 2 °C per minute, and anneal for 2 hours.
[0095] At a current density of 10 mA / cm³, the overpotential is 104 mV.
[0096] Example 4
[0097] 1. Preparation of Ni-Co Nanoprisms
[0098] (1) Weigh 1.3 g of nickel acetate tetrahydrate and 1.3 g of cobalt acetate tetrahydrate, ultrasonically disperse them in 200 mL of absolute ethanol, and then add 3.0 g of polyvinylpyrrolidone (PVP) under stirring, and stir at room temperature for 30 minutes.
[0099] (2) Transfer this mixed solution to a 200 mL round-bottom flask, place it in an oil bath, and reflux it at 85 °C for 4 hours.
[0100] (3) After cooling to room temperature, centrifuge the product to remove the supernatant, wash it with deionized water, and then dry it in a vacuum drying oven at 80 °C for 16 hours. Obtain the Ni-Co nanopyramid precursor.
[0101] 2. Preparation of Ni-Co-S / NiCo-prisms Precursors
[0102] Take 60 mg of the above-prepared Ni-Co nanopyramid precursor, ultrasonically disperse it in 60 mL of ethanol, and then slowly add 0.5 mL of ammonium sulfide aqueous solution under stirring. After stirring for 30 minutes, centrifuge the product to remove the supernatant, wash it 3 times with deionized water and absolute ethanol respectively, and dry it in a vacuum drying oven at 60 °C for 12 hours.
[0103] 3. Preparation of Ni3S4@Co9S8@NC
[0104] Weigh 30 mg of the above sample into a porcelain boat, cover it with a glass slide, place it in a tube furnace, and under the protection of N2, heat it to 350 °C at a heating rate of 2 °C per minute, and anneal for 2 hours.
[0105] At a current density of 10 mA / cm³, the overpotential is 140 mV.
[0106] Example 5
[0107] 1. Preparation of Ni-Co Nanoprisms
[0108] (1) Weigh 1.3 g of nickel acetate tetrahydrate and 1.3 g of cobalt acetate tetrahydrate, ultrasonically disperse them in 200 mL of absolute ethanol, and then add 3.0 g of polyvinylpyrrolidone (PVP) under stirring. Stir at room temperature for 30 minutes.
[0109] (2) Transfer this mixed solution to a 200 mL round-bottom flask, place it in an oil bath, and carry out condensation reflux at 85 °C for 4 hours.
[0110] (3) After cooling to room temperature, centrifuge the product to remove the supernatant, wash it several times with absolute ethanol, and then dry it in a vacuum drying oven at 60 °C for 12 hours. Obtain the Ni-Co nanopyramid precursor.
[0111] 2. Preparation of Ni-Co-S / NiCo-prisms Precursors
[0112] Take 80 mg of the above-prepared Ni-Co nanopyramid precursor, ultrasonically disperse it in 80 mL of ethanol, and then slowly add 1 mL of aqueous ammonium sulfide solution dropwise under stirring. After stirring for 40 minutes, centrifuge the product to remove the supernatant, wash it 4 times with deionized water and absolute ethanol respectively, and dry it in a vacuum drying oven at 80 °C for 16 hours.
[0113] 3. Preparation of Ni3S4@Co9S8@NC
[0114] Weigh 30 mg of the above sample into a porcelain boat, cover it with a glass slide, place it in a tube furnace, and under the protection of N2, heat it to 350 °C at a heating rate of 2 °C per minute and anneal for 2 hours.
[0115] At a current density of 10 mA / cm³, the overpotential is 128 mV.
[0116] Example 6
[0117] 1. Preparation of Ni-Co Nanoprisms
[0118] (1) Weigh 1.3 g of nickel acetate tetrahydrate and 1.3 g of cobalt acetate tetrahydrate, ultrasonically disperse them in 200 mL of absolute ethanol, and then add 3.0 g of polyvinylpyrrolidone (PVP) under stirring. Stir at room temperature for 30 minutes.
[0119] (2) Transfer this mixed solution to a 200 mL round-bottom flask, place it in an oil bath, and carry out condensation reflux at 85 °C for 4 hours.
[0120] (3) After cooling to room temperature, centrifuge the product to remove the supernatant, wash it several times with absolute ethanol, and then dry it in a vacuum drying oven at 60 °C for 12 hours. Obtain the Ni-Co nanopyramid precursor.
[0121] 2. Preparation of Ni-Co-S / NiCo-prisms Precursors
[0122] Take 60 mg of the above-prepared Ni-Co nanopyramid precursor and ultrasonically disperse it in 60 mL of ethanol. Subsequently, slowly drop 0.5 mL of aqueous ammonium sulfide solution under stirring. After stirring for 30 minutes, centrifuge the product to remove the supernatant, wash it three times with deionized water and absolute ethanol respectively, and place it in a vacuum drying oven at 60 °C for 12 hours.
[0123] 3. Preparation of Ni3S4@Co9S8@NC
[0124] Weigh 40 mg of the above sample into a porcelain boat, cover it with a glass slide and place it in a tube furnace. Under H2 protection, heat it to 450 °C at a heating rate of 5 °C per minute and anneal for 3 hours.
[0125] At a current density of 10 mA / cm³, the overpotential is 129 mV.
[0126] The specific embodiments of the present application have been described in detail above, but they are only examples, and the present application is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present application are also within the scope of the present application. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of the present application should be covered within the scope of the present application.
Claims
1. A preparation method of Ni3S4@Co9S8@NC electrocatalyst, characterized in that the steps It includes: a nickel source, a cobalt source and a surfactant are dispersed in a solvent, and after heating, the solid is collected; The collected solid is reacted with a sulfur source to sulfide at least part of Ni and Co to obtain an intermediate; The intermediate is annealed, Ni and Co are respectively transformed into highly crystalline Ni3S4 and Co9S8, and the organic components in the intermediate are transformed into nitrogen-doped carbon to form a Ni3S4@Co9S8@NC electrocatalyst.
2. The preparation method according to claim 1, characterized in that, The nickel source is a nickel salt, selected from inorganic acid salts or organic acid salts, for example, it can be selected from: nickel nitrate, nickel carbonate, nickel chloride, nickel bromide, nickel sulfate, nickel acetate, nickel formate, nickel citrate; The cobalt source is a cobalt salt, selected from inorganic acid salts or organic acid salts, for example, it can be selected from: cobalt nitrate, cobalt chloride, cobalt bromide, cobalt sulfate, cobalt phosphate, cobalt carbonate, cobalt acetate, cobalt formate, cobalt oxalate, cobalt aminosulfonate, cobalt acetylacetonate, etc.; The A can be selected from one of polyvinylpyrrolidone, polyvinyl alcohol, sodium citrate, sodium borohydride, ammonium formate, sodium hypochlorite, benzenesulfonic acid, sodium azide, potassium iodide; The solvent is selected from water, alcohols, esters, ethers, ketones, aldehydes, carboxylic acids, hydrocarbons, sulfones, nitriles, etc., for example, it can be selected from water, methanol, ethanol, propanol, isopropanol, ethylene glycol, ethyl acetate, butyl acetate, acetone, diethyl ether, petroleum ether, dimethyl sulfoxide, acetonitrile, halogenated hydrocarbons, aromatic hydrocarbons, tetrahydrofuran, etc.; The sulfur source is a compound capable of providing S 2- , such as hydrosulfide salts, and more preferably may be selected from ammonium sulfide, sodium sulfide, potassium sulfide, iron sulfide, ferrous sulfide, copper sulfide, magnesium sulfide, zinc sulfide, calcium sulfide, mercury sulfide, cadmium sulfide, lead sulfide, barium sulfide.
3. The preparation method according to claim 1, characterized in that, The nickel source, the cobalt source and the surfactant are heated to 50 - 150 °C, preferably heated to 60 - 120 °C, more preferably 70 - 100 °C, and even more preferably 80 - 90 °C; The heating time of the nickel source, the cobalt source and the surfactant together is at least 15 minutes, more preferably at least 30 minutes, more preferably 0.5 - 12 hours, more preferably 1 - 10 hours, more preferably 2 - 9 hours, more preferably 3 - 7 hours, more preferably 4 - 6 hours; The reaction time of the collected solid with the sulfur source is at least 1 minute, more preferably at least 2 minutes, more preferably at least 5 minutes, more preferably 10 - 60 minutes, more preferably 20 - 45 minutes, more preferably 30 - 40 minutes; during the annealing process of the intermediate, the heating temperature is 50 - 800 °C, more preferably 80 - 600 °C, more preferably 100 - 500 °C, more preferably 150 - 450 °C, more preferably 200 - 400 °C, more preferably 250 - 350 °C; during the annealing process of the intermediate, the heating time is at least 5 minutes, more preferably at least 10 minutes, more preferably at least 15 minutes, more preferably 0.5 - 6 hours, more preferably 1 - 4 hours; During the annealing process of the intermediate, the heating and cooling rates are independently selected from 1 - 10 °C / min, more preferably 3 - 8 °C / min, and more preferably 5 - 7 °C / min.
4. The preparation method according to claim 1, wherein The molar ratio of Ni to Co of the nickel source and the cobalt source is 1:(0.5 - 1.5), more preferably 1:(0.7 - 1.2), such as 1:0.8, 1:1, 1; The molar volume concentration of the nickel source in the solvent is (1-5)×10 -5 mol / ml, more preferably (1.5-4)×10 -5 mol / ml, more preferably (2-3)×10 -5 mol / ml; The mass volume concentration of A in the volume (weight of A in g per ml of solution) is preferably 0.001 - 1 g / ml, more preferably 0.005 - 0.8 g / ml, more preferably 0.01 - 0.5 g / ml, and more preferably 0.1 - 0.3 g / ml.
5. The preparation method according to claim 1, characterized in that, The collected solid and the sulfur source are dispersed in a second solvent and reacted. Among them, the second solvent is selected from water, alcohols, esters, ethers, ketones, aldehydes, carboxylic acids, hydrocarbons, sulfones, nitriles, etc. For example, it can be selected from water, methanol, ethanol, propanol, isopropanol, ethylene glycol, ethyl acetate, butyl acetate, acetone, diethyl ether, petroleum ether, dimethyl sulfoxide, acetonitrile, halogenated hydrocarbons, aromatic hydrocarbons, and tetrahydrofuran.
6. The preparation method according to claim 5, characterized in that, The sulfur source is a compound that can be dissolved in the second solvent, or is added to the second solvent after being dissolved in a third solvent. Among them, the third solvent is selected from water, alcohols, esters, ethers, ketones, aldehydes, carboxylic acids, hydrocarbons, sulfones, nitriles, etc. For example, it can be selected from water, methanol, ethanol, propanol, isopropanol, ethylene glycol, ethyl acetate, butyl acetate, acetone, diethyl ether, petroleum ether, dimethyl sulfoxide, acetonitrile, halogenated hydrocarbons, aromatic hydrocarbons, and tetrahydrofuran.
7. The preparation method according to claim 1, characterized in that, The intermediate is annealed under an inert gas condition; the inert gas is selected from one or more of nitrogen, argon, and hydrogen.
8. A Ni3S4@Co9S8@NC electrocatalyst prepared by the preparation method described in claim 1.
9. Use of the Ni3S4@Co9S8@NC electrocatalyst according to claim 8, characterized in that, The Ni3S4@Co9S8@NC electrocatalyst is used in an electrocatalytic method and / or an electrocatalytic device. Preferably, it is used as an electrocatalyst for hydrogen evolution reaction.
10. The application according to claim 9, wherein The Ni3S4@Co9S8@NC electrocatalyst is used to prepare an electrolysis electrode. More preferably, the electrolysis is the electrolysis of water, and more preferably, it is the electrolysis of alkaline water.