An F-doped Ni3S2 bifunctional self-supporting electrocatalyst and its preparation method
By hydrothermally synthesizing Ni3S2 nanoarrays on a nickel foam substrate and doping F with NH4F solution, an F-doped Ni3S2 bifunctional electrocatalyst was prepared, solving the problems of complex preparation and high risk in the prior art, and achieving high efficiency in hydrogen evolution and oxygen evolution reactions.
Patent Information
- Application Number
- CN202311461095.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-06
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2043-11-06
AI Technical Summary
The existing preparation process of F-doped Ni3S2 catalysts is complex and dangerous, and there are few electrochemical active sites, resulting in high overpotentials for the electrocatalysts in the hydrogen evolution and oxygen evolution reactions, making it difficult to achieve efficient bifunctional catalytic performance.
A Ni3S2 nanoarray was constructed in situ on a nickel foam substrate using a hydrothermal synthesis method, and F-doped by soaking in a supersaturated NH4F solution to form Ni-F bonds, thus preparing an F-doped Ni3S2 bifunctional self-supporting electrocatalyst.
The preparation process was simplified, the experimental risks were reduced, and the electrochemical activity of the catalyst was improved. The overpotential of the oxygen evolution reaction was reduced by 206 mV and the overpotential of the hydrogen evolution reaction was reduced by 61 mV, demonstrating excellent electrocatalytic performance.
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Figure CN117244569B_ABST
Abstract
Description
Technical fields:
[0001] This invention relates to a method for preparing an F-doped Ni3S2 bifunctional self-supporting electrocatalyst using a supersaturated NH4F solution, belonging to the field of catalytic hydrogen evolution and oxygen evolution technology. Background technology:
[0002] In the 21st century, due to environmental pollution and the energy crisis, hydrogen energy generated by electrochemical water separation technology has attracted widespread attention. However, the delay in electron transfer processes and the participation of multiple intermediate species (such as H*, OH*, OOH*) in the hydrogen evolution reaction and oxygen evolution reaction lead to relatively high water electrolysis overpotentials. The most efficient HER and OER catalysts are still considered to be Pt-based and IrO2 materials, but their large-scale industrial production faces significant obstacles. Furthermore, materials exhibiting high catalytic activity for both HER and OER are extremely rare. Among the various existing catalytic materials, nickel-based sulfide materials such as NiS, Ni3S2, and NiS2 are considered potential alternatives to noble metal electrocatalysts due to their low cost, diverse valence states, and high conductivity.
[0003] Recent studies have shown that the incorporation of F atoms into the Ni3S2 lattice leads to strong electronic coupling between metal cations and non-metal anions, thereby increasing the d-band. This not only optimizes the hydrogen adsorption energy but also facilitates the dissociation of water molecules on the catalyst surface (see Xu, Q, et al. Fluorine-triggered surface reconstruction of Ni3S2 electrocatalysts towards enhanced water oxidation. Chemical Engineering Journal, 2021, 411.). This paper employs a molten salt fluorination method, utilizing the high-temperature decomposition of NH4F to generate trace amounts of hydrofluoric acid, which corrodes Ni3S2 and reconstructs its surface morphology, ultimately resulting in the formation of ultrathin, low-crystalline nanosheets on the surface of the Ni3S2 nanoarray. Although previous studies have optimized and improved the morphology, conductivity, and intrinsic activity of Ni3S2. However, F-doped Ni3S2 has fewer active sites, resulting in a lower electrochemical surface area; the preparation process is relatively dangerous, with the hydrofluoric acid produced by high-temperature decomposition being highly corrosive to glassware, and solid NH4F being difficult to melt upon heating; a small amount of elemental nickel remains after the sulfidation and fluorination of nickel foam, which somewhat affects its catalytic principle research; and it only exhibits high catalytic efficiency for the oxygen evolution reaction. Therefore, a bifunctional F-doped Ni3S2 electrocatalyst with a simple preparation process and high intrinsic electrochemical activity is needed. Summary of the Invention:
[0004] The purpose of this invention is to address the shortcomings of current technologies by providing an F-doped Ni3S2 bifunctional self-supporting electrocatalyst and its preparation method. This method involves hydrothermally synthesizing a Ni3S2 substrate, which is then immersed in a supersaturated NH4F solution. Due to the strong hygroscopic nature of the nickel foam structure, a large number of NH4F molecules are adsorbed into the Ni3S2 structure. Water and ammonia molecules are removed by simple heating. The small amount of hydrofluoric acid produced by the thermal decomposition of NH4F corrodes the Ni3S2 substrate and elemental nickel, forming numerous Ni-F bonds. The catalyst prepared by this invention not only innovates in its method but also exhibits high catalytic efficiency for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with the OER reaching high efficiency at 50 mA cm⁻¹. -2 At this current density, the overpotential is only 168 mV, and the Tafel slope is 71.5 mV dec. -1 The hydrogen evolution reaction occurs at 10 mA cm⁻¹ -2 At the given current density, the overpotential is 83 mV, and the Tafel slope is 88.6 mV dec. -1 At a current density of 10 mA cm⁻¹ -2 Under these conditions, the overall water splitting voltage is 1.42V, which is better than that of the Pt / C / / RuO2 two-electrode system (1.61V).
[0005] The technical solution adopted in this invention is as follows:
[0006] An F-doped Ni3S2 bifunctional self-supporting electrocatalyst is disclosed. The catalyst uses the three-dimensional porous structure of nickel foam as a self-supporting framework. Ni3S2 is constructed in situ on the surface of its pores, and then F-doped Ni3S2 nanoarrays (with an array thickness of 2.5 mm to 3.5 mm) are synthesized by acid etching. The ratio of Ni to S is 3:2, the F doping amount is 2% to 30%, and the surface morphology of the nanoarray is a cylindrical rod (length 1 to 5 μm, diameter 0.2 to 1.2 μm). F, Ni, and S elements are uniformly distributed on the surface.
[0007] The method for preparing the F-doped Ni3S2 bifunctional self-supporting electrocatalyst includes the following steps:
[0008] Step 1: The nickel foam is ultrasonically treated in dilute sulfuric acid solution, deionized water and anhydrous ethanol in sequence, and then dried at room temperature;
[0009] The described nickel foam has a porosity of 50 ppi to 120 ppi and a thickness of 2.8 to 3.2 mm.
[0010] The concentration of the dilute sulfuric acid is 0.1 mol / L. -1 ~2mol L -1 The ultrasonic treatment time is 10 to 30 minutes.
[0011] The purity of the anhydrous ethanol is 99.7%;
[0012] Step 2: Disperse thioacetamide and urea in deionized water and stir magnetically for 0.5 to 2.5 hours to obtain a colorless and transparent solution;
[0013] Add 0.1g to 0.5g of thioacetamide and 0.2g to 0.5g of urea to every 30ml to 50ml of deionized water;
[0014] Step 3: Place the cleaned nickel foam from Step 1 and the solution prepared in Step 2 into a reaction vessel lined with para-polystyrene (PPL), and perform a hydrothermal reaction at 160℃~240℃ for 8 to 16 hours, followed by forced air cooling to room temperature; after cleaning, a Ni3S2 substrate loaded on nickel foam is obtained.
[0015] Step 4: Immerse the Ni3S2 substrate obtained in the previous step in a supersaturated solution of NH4F for 10 minutes to 400 minutes to obtain the Ni3S2 wetted state;
[0016] In the supersaturated solution of NH4F, 2-6 g of NH4F is added to every 1-10 mL of deionized water;
[0017] Step 5: Place the Ni3S2 wetted state obtained in the previous step into a boat and heat it at 200-1000℃ for 10-500 minutes to obtain the F-doped Ni3S2 bifunctional electrocatalyst.
[0018] The ark is made of corundum.
[0019] The F-doped Ni3S2 bifunctional self-supporting electrocatalyst is used in the field of full water electrolysis.
[0020] Specifically, a three-electrode system is used, with the working electrode being an F-doped Ni3S2 bifunctional self-supporting electrocatalyst, the counter electrode being a carbon rod, and the reference electrode being a saturated calomel electrode, to perform electrolytic catalytic hydrogen and oxygen production.
[0021] The alkaline electrolyte is 0.1 mol / L. -1 ~2mol L -1 KOH solution;
[0022] Electrolysis is performed at a constant voltage, with a voltage range of 1.5V to 1.8V.
[0023] The invention has the following beneficial effects.
[0024] 1. The present invention discloses a method for preparing F-doped Ni3S2 bifunctional self-supporting electrocatalyst using supersaturated NH4F solution. The method uses nickel foam as a conductive substrate, which avoids catalyst agglomeration and the use of binders, and at the same time significantly improves the performance of HER and OER.
[0025] 2. In this invention, the doping of F induces electron transfer between Ni and S, while simultaneously forming hydrogen bonds between F and water. According to Grotthuss theory, the increased number of hydrogen bonds between water molecules leads to greater efficiency in the transfer of intermediate products H* and OH*. Compared to Ni3S2, the F-doped Ni3S2 self-supporting electrocatalyst exhibits a 206 mV reduction in the oxygen evolution reaction overpotential and a 61 mV reduction in the hydrogen evolution reaction overpotential.
[0026] 3. In this invention, the element F is doped into Ni3S2 by simple acid etching. Compared with the previous research on the synthesis of F-doped Ni3S2 nanosheets by multiple steps (see He, W, et al. Fluorine-Anion-Modulated Electron Structure of Nickel Sulfide Nanosheet Arrays for Alkaline Hydrogen Evolution. ACS Energy Letters 4(12):2905-2912.), the preparation process is simpler and takes only 8 to 15 hours.
[0027] 4. This invention synthesizes F-doped Ni3S2 bifunctional electrocatalysts through processes such as soaking and heating. Compared with previous studies on the synthesis of F-doped Ni3S2 nanorods by high-temperature molten salt method (see literature Xu, Q, et al. Fluorine-triggered surface reconstruction of Ni3S2 electrocatalysts towards enhanced water oxidation. Chemical Engineering Journal 411.), it avoids the sputtering of NH4F solid and the corrosion of glassware by hydrofluoric acid formed by high-temperature thermal decomposition, thus reducing the danger of the experiment.
[0028] 5. The bifunctional catalyst prepared by this invention exhibits good stability, with its hydrogen evolution reaction and oxygen evolution reaction occurring within -40 mA cm⁻¹. -2 and 50mA cm -2 It can remain stable for 48 hours at any current density, and the F content will decrease as the reaction proceeds. Attached image description:
[0029] Figure 1 The image shows the XRD pattern of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst in Example 1.
[0030] Figure 2 This is a SEM image of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst in Example 1.
[0031] Figure 3 The image shows the EDS image of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst in Example 1.
[0032] Figure 4 This is a TEM image of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst in Example 1.
[0033] Figure 5 This is a TEM mapping image of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst in Example 1.
[0034] Figure 6 The image shows the XPS charge transfer spectrum of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst in Example 1.
[0035] Figure 7 The figures show the electrochemical hydrogen evolution polarization curves and corresponding Tafel slope diagrams of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst in 1M KOH solution in Example 1. Figure 7 (a) is the electrochemical hydrogen evolution polarization curve. Figure 7 (b) is the Tafel slope diagram;
[0036] Figure 8 The figures show the electrochemical oxygen evolution polarization curves and corresponding Tafel slopes of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst in 1M KOH solution in Example 1. Figure 8 (a) is the electrochemical oxygen evolution polarization curve. Figure 8 (b) is the Tafel slope diagram;
[0037] Figure 9 The figures show the 48-hour IT test curves of OER and HER in 1M KOH solution of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst in Example 1. Figure 9 (a) OER at 50 mAcm -2 IT test curves under current density Figure 9 (b) HER at -40 mAcm -2 IT test curves at current density;
[0038] Figure 10 This is a comparison of the electrochemical oxygen evolution polarization curves of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst in 1M KOH solution at different heating times.
[0039] Figure 11 This is a comparison of the electrochemical hydrogen evolution polarization curves of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst in 1M KOH solution at different heating times.
[0040] Figure 12 This is a comparison of data from other literature for F-doped Ni3S2 bifunctional self-supporting electrocatalysts. Detailed Implementation
[0041] The following detailed description of examples of the present invention is provided in conjunction with the accompanying drawings.
[0042] Example 1:
[0043] A method for preparing an F-doped Ni3S2 bifunctional self-supporting electrocatalyst using a supersaturated NH4F solution, comprising the following steps:
[0044] Step 1: Using nickel foam with dimensions of 2cm*4cm, a thickness of 3.0mm, and a porosity of 75ppi as the nickel source, immerse it in 10mL of 1mol L⁻¹ nickel solution. -1 The samples were ultrasonically cleaned for 25 minutes each in dilute sulfuric acid solution, deionized water, and anhydrous ethanol, and then air-dried at room temperature.
[0045] Step 2: Disperse 0.4g of thioacetamide and 0.3g of urea in 40mL of deionized water, add a magnetic stir bar and stir for 40 minutes to obtain a colorless and transparent solution.
[0046] Step 3: Place the cleaned nickel foam from Step 1 and the solution prepared in Step 2 into a reactor lined with para-polystyrene. Heat the reactor to 200°C in an oven for a closed hydrothermal reaction for 12 hours, and then cool it to room temperature with a forced airflow.
[0047] Step 4: Remove the sample from the hydrothermal reaction in Step 3 from the reactor, wash it with deionized water and anhydrous ethanol in small amounts several times, and then set it aside for later use to obtain the Ni3S2 substrate.
[0048] Step 5: Disperse 3g of NH4F in 2mL of deionized water and sonicate for 3 minutes to obtain a supersaturated solution.
[0049] Step 6: Immerse the Ni3S2 prepared in Step 4 in the supersaturated NH4F solution prepared in Step 5 in a 50mL beaker and soak at room temperature for 20 minutes.
[0050] Step 7: Place the sample soaked in Step 6 into a corundum ark and heat it at 300°C for 10 minutes in a fume hood.
[0051] Step 8: Remove the electrocatalyst that was heat-treated in Step 7 from the boat, and wash it with deionized water and anhydrous ethanol in small amounts and multiple times to obtain the F-doped Ni3S2 bifunctional self-supporting electrocatalyst.
[0052] Electrochemical tests in this patent were performed on a CHI750E, and stability tests were performed on a CHI660E. A three-electrode system was used. An F-doped Ni3S2 bifunctional self-supporting electrocatalyst was used as the working electrode, a carbon rod as the counter electrode, and a saturated calomel electrode as the reference electrode. The electrolyte was 1M KOH (pH = 13.7) under alkaline conditions. Before testing, N2 was bubbled into the solution for 30 minutes to achieve N2 saturation. The electrode potential was converted to a reversible hydrogen electrode potential using the Nernst equation. In HER and OER tests, the voltage ranges were -1.07 to -1.77 V (vs. RHE) and 0 to 0.9 V (vs. RHE), respectively, with a scan rate of 5 mV / s. -1 .
[0053] Figure 1 The image shows the XRD pattern of Ni3S2, with no other components present.
[0054] Figure 2 The image shows an SEM image of F-doped Ni3S2, clearly showing rod-shaped growths on the pore walls of the nickel foam, with a uniform distribution.
[0055] Figure 3 The EDS image from SEM shows that the F element doping content is 2% to 30%, and the atomic ratio of Ni to S elements is close to 3:2. The substance can be specifically identified as F-doped Ni3S2.
[0056] Figure 4 The TEM image shows F-doped Ni3S2, which appears to be short rod-shaped (2.5–3 μm in length and 0.3–0.6 μm in width).
[0057] Figure 5 The TEM mapping (from left to right: original image, element F, element Ni, element S) shows the uniform distribution of F, Ni, and S elements.
[0058] Figure 6 The XPS electron transfer spectrum of Ni shows that the Ni 2p peak has shifted to a certain extent relative to the original peak. The doping of F caused some electron transfer in Ni atoms, indicating that F may have pulled an electron out of Ni atoms, thereby reducing the electron density around Ni atoms.
[0059] Figure 7 and Figure 8 Electrochemical hydrogen evolution and oxygen evolution polarization curves and corresponding Tafel slope plots for F-doped Ni3S2, in 1M KOH solution, at 50 mA / cm². -2 The overpotential at current density is 168 mV, and the HER response occurs at 10 mA cm⁻¹. -2The overpotential at the current density is 83 mV, indicating that the F-doped Ni3S2 bifunctional catalyst has excellent electrochemical performance.
[0060] Figure 9 For stability testing of F-doped Ni3S2, oxygen evolution reaction and hydrogen evolution reaction were performed at 50 mA cm⁻¹. -2 and -40mAcm -2 It can remain stable for 48 hours under the specified current density. However, the catalytic performance is reduced due to the continuous consumption of F during the test.
[0061] Example 2:
[0062] A method for preparing an F-doped Ni3S2 bifunctional self-supporting electrocatalyst using a supersaturated NH4F solution, comprising the following steps:
[0063] Step 1: Using nickel foam with dimensions of 2cm*4cm, a thickness of 3.0mm, and a porosity of 75ppi as the nickel source, immerse it in 10mL of 1mol L⁻¹ nickel solution. -1 The samples were ultrasonically cleaned for 25 minutes each in dilute sulfuric acid solution, deionized water, and anhydrous ethanol, and then air-dried at room temperature.
[0064] Step 2: Disperse 0.4g of thioacetamide and 0.3g of urea in 40mL of deionized water, add a magnetic stir bar and stir for 40 minutes to obtain a colorless and transparent solution.
[0065] Step 3: Place the cleaned nickel foam from Step 1 and the solution prepared in Step 2 into a reactor lined with para-polystyrene. Heat the reactor to 200°C in an oven for a closed hydrothermal reaction for 12 hours, and then cool it to room temperature with a forced airflow.
[0066] Step 4: Remove the sample from the hydrothermal reaction in Step 3 from the reactor, wash it with deionized water and anhydrous ethanol in small amounts several times, and then set it aside for later use to obtain the Ni3S2 substrate.
[0067] Step 5: Disperse 3g of NH4F in 2mL of deionized water and sonicate for 3 minutes to obtain a supersaturated solution.
[0068] Step 6: Immerse the Ni3S2 prepared in Step 4 in the supersaturated NH4F solution prepared in Step 5 in a 50mL beaker and soak at room temperature for 20 minutes.
[0069] Step 7: Place the sample soaked in Step 6 into a corundum ark and heat it at 300°C for 30 minutes in a fume hood.
[0070] Step 8: Remove the electrocatalyst that was heat-treated in Step 7 from the boat, and wash it with deionized water and anhydrous ethanol in small amounts and multiple times to obtain the F-doped Ni3S2 bifunctional self-supporting electrocatalyst.
[0071] Example 3:
[0072] A method for preparing an F-doped Ni3S2 bifunctional self-supporting electrocatalyst using a supersaturated NH4F solution, comprising the following steps:
[0073] Step 1: Using nickel foam with dimensions of 2cm*4cm, a thickness of 3.0mm, and a porosity of 75ppi as the nickel source, immerse it in 10mL of 1mol L⁻¹ nickel solution. -1 The samples were ultrasonically cleaned for 25 minutes each in dilute sulfuric acid solution, deionized water, and anhydrous ethanol, and then air-dried at room temperature.
[0074] Step 2: Disperse 0.4g of thioacetamide and 0.3g of urea in 40mL of deionized water, add a magnetic stir bar and stir for 40 minutes to obtain a colorless and transparent solution.
[0075] Step 3: Place the cleaned nickel foam from Step 1 and the solution prepared in Step 2 into a reactor lined with para-polystyrene. Heat the reactor to 200°C in an oven for a closed hydrothermal reaction for 12 hours, and then cool it to room temperature with a forced airflow.
[0076] Step 4: Remove the sample from the hydrothermal reaction in Step 3 from the reactor, wash it with deionized water and anhydrous ethanol in small amounts several times, and then set it aside for later use to obtain the Ni3S2 substrate.
[0077] Step 5: Disperse 3g of NH4F in 2mL of deionized water and sonicate for 3 minutes to obtain a supersaturated solution.
[0078] Step 6: Immerse the Ni3S2 prepared in Step 4 in the supersaturated NH4F solution prepared in Step 5 in a 50mL beaker and soak at room temperature for 20 minutes.
[0079] Step 7: Place the sample soaked in Step 6 into a corundum ark and heat it at 300°C for 50 minutes in a fume hood.
[0080] Step 8: Remove the electrocatalyst that was heat-treated in Step 7 from the boat, and wash it with deionized water and anhydrous ethanol in small amounts and multiple times to obtain the F-doped Ni3S2 bifunctional self-supporting electrocatalyst.
[0081] Example 4:
[0082] A method for preparing an F-doped Ni3S2 bifunctional self-supporting electrocatalyst using a supersaturated NH4F solution, comprising the following steps:
[0083] Step 1: Using nickel foam with dimensions of 2cm*4cm, a thickness of 3.0mm, and a porosity of 75ppi as the nickel source, immerse it in 10mL of 1mol L⁻¹ nickel solution. -1 The samples were ultrasonically cleaned for 25 minutes each in dilute sulfuric acid solution, deionized water, and anhydrous ethanol, and then air-dried at room temperature.
[0084] Step 2: Disperse 0.4g of thioacetamide and 0.3g of urea in 40mL of deionized water, add a magnetic stir bar and stir for 40 minutes to obtain a colorless and transparent solution.
[0085] Step 3: Place the cleaned nickel foam from Step 1 and the solution prepared in Step 2 into a reactor lined with para-polystyrene. Heat the reactor to 200°C in an oven for a closed hydrothermal reaction for 12 hours, and then cool it to room temperature with a forced airflow.
[0086] Step 4: Remove the sample from the hydrothermal reaction in Step 3 from the reactor, wash it with deionized water and anhydrous ethanol in small amounts several times, and then set it aside for later use to obtain the Ni3S2 substrate.
[0087] Step 5: Disperse 3g of NH4F in 2mL of deionized water and sonicate for 3 minutes to obtain a supersaturated solution.
[0088] Step 6: Immerse the Ni3S2 prepared in Step 4 in the supersaturated NH4F solution prepared in Step 5 in a 50mL beaker and soak at room temperature for 20 minutes.
[0089] Step 7: Place the sample soaked in Step 6 into a corundum ark and heat it at 300°C for 70 minutes in a fume hood.
[0090] Step 8: Remove the electrocatalyst that was heat-treated in Step 7 from the boat, and wash it with deionized water and anhydrous ethanol in small amounts and multiple times to obtain the F-doped Ni3S2 bifunctional self-supporting electrocatalyst.
[0091] Example 5:
[0092] A method for preparing an F-doped Ni3S2 bifunctional self-supporting electrocatalyst using a supersaturated NH4F solution, comprising the following steps:
[0093] Step 1: Using nickel foam with dimensions of 2cm*4cm, a thickness of 3.0mm, and a porosity of 75ppi as the nickel source, immerse it in 10mL of 1mol L⁻¹ nickel solution. -1 The samples were ultrasonically cleaned for 25 minutes each in dilute sulfuric acid solution, deionized water, and anhydrous ethanol, and then air-dried at room temperature.
[0094] Step 2: Disperse 0.4g of thioacetamide and 0.3g of urea in 40mL of deionized water, add a magnetic stir bar and stir for 40 minutes to obtain a colorless and transparent solution.
[0095] Step 3: Place the cleaned nickel foam from Step 1 and the solution prepared in Step 2 into a reactor lined with para-polystyrene. Heat the reactor to 200°C in an oven for a closed hydrothermal reaction for 12 hours, and then cool it to room temperature with a forced airflow.
[0096] Step 4: Remove the sample from the hydrothermal reaction in Step 3 from the reactor, wash it with deionized water and anhydrous ethanol in small amounts several times, and then set it aside for later use to obtain the Ni3S2 substrate.
[0097] Step 5: Disperse 3g of NH4F in 2mL of deionized water and sonicate for 3 minutes to obtain a supersaturated solution.
[0098] Step 6: Immerse the Ni3S2 prepared in Step 4 in the supersaturated NH4F solution prepared in Step 5 in a 50mL beaker and soak at room temperature for 40 minutes.
[0099] Step 7: Place the sample soaked in Step 6 into a corundum ark and heat it at 300°C for 10 minutes in a fume hood.
[0100] Step 8: Remove the electrocatalyst that was heat-treated in Step 7 from the boat, and wash it with deionized water and anhydrous ethanol in small amounts and multiple times to obtain the F-doped Ni3S2 bifunctional self-supporting electrocatalyst.
[0101] Example 6:
[0102] A method for preparing an F-doped Ni3S2 bifunctional self-supporting electrocatalyst using a supersaturated NH4F solution, comprising the following steps:
[0103] Step 1: Using nickel foam with dimensions of 2cm*4cm, a thickness of 3.0mm, and a porosity of 75ppi as the nickel source, immerse it in 10mL of 1mol L⁻¹ nickel solution. -1 The samples were ultrasonically cleaned for 25 minutes each in dilute sulfuric acid solution, deionized water, and anhydrous ethanol, and then air-dried at room temperature.
[0104] Step 2: Disperse 0.4g of thioacetamide and 0.3g of urea in 40mL of deionized water, add a magnetic stir bar and stir for 40 minutes to obtain a colorless and transparent solution.
[0105] Step 3: Place the cleaned nickel foam from Step 1 and the solution prepared in Step 2 into a reactor lined with para-polystyrene. Heat the reactor to 200°C in an oven for a closed hydrothermal reaction for 12 hours, and then cool it to room temperature with a forced airflow.
[0106] Step 4: Remove the sample from the hydrothermal reaction in Step 3 from the reactor, wash it with deionized water and anhydrous ethanol in small amounts several times, and then set it aside for later use to obtain the Ni3S2 substrate.
[0107] Step 5: Disperse 3g of NH4F in 2mL of deionized water and sonicate for 3 minutes to obtain a supersaturated solution.
[0108] Step 6: Immerse the Ni3S2 prepared in Step 4 in the supersaturated NH4F solution prepared in Step 5 in a 50mL beaker and soak at room temperature for 60 minutes.
[0109] Step 7: Place the sample soaked in Step 6 into a corundum ark and heat it at 300°C for 10 minutes in a fume hood.
[0110] Step 8: Remove the electrocatalyst that was heat-treated in Step 7 from the boat, and wash it with deionized water and anhydrous ethanol in small amounts and multiple times to obtain the F-doped Ni3S2 bifunctional self-supporting electrocatalyst.
[0111] Example 7:
[0112] A method for preparing an F-doped Ni3S2 bifunctional self-supporting electrocatalyst using a supersaturated NH4F solution, comprising the following steps:
[0113] Step 1: Using nickel foam with dimensions of 2cm*4cm, a thickness of 3.0mm, and a porosity of 75ppi as the nickel source, immerse it in 10mL of 1mol L⁻¹ nickel solution. -1 The samples were ultrasonically cleaned for 25 minutes each in dilute sulfuric acid solution, deionized water, and anhydrous ethanol, and then air-dried at room temperature.
[0114] Step 2: Disperse 0.4g of thioacetamide and 0.3g of urea in 40mL of deionized water, add a magnetic stir bar and stir for 40 minutes to obtain a colorless and transparent solution.
[0115] Step 3: Place the cleaned nickel foam from Step 1 and the solution prepared in Step 2 into a reactor lined with para-polystyrene. Heat the reactor to 200°C in an oven for a closed hydrothermal reaction for 12 hours, and then cool it to room temperature with a forced airflow.
[0116] Step 4: Remove the sample from the hydrothermal reaction in Step 3 from the reactor, wash it with deionized water and anhydrous ethanol in small amounts several times, and then set it aside for later use to obtain the Ni3S2 substrate.
[0117] Step 5: Disperse 3g of NH4F in 2mL of deionized water and sonicate for 3 minutes to obtain a supersaturated solution.
[0118] Step 6: Immerse the Ni3S2 prepared in Step 4 in the supersaturated NH4F solution prepared in Step 5 in a 50mL beaker and soak at room temperature for 80 minutes.
[0119] Step 7: Place the sample soaked in Step 6 into a corundum ark and heat it at 300°C for 10 minutes in a fume hood.
[0120] Step 8: Remove the electrocatalyst that was heat-treated in Step 7 from the boat, and wash it with deionized water and anhydrous ethanol in small amounts and multiple times to obtain the F-doped Ni3S2 bifunctional self-supporting electrocatalyst.
[0121] Example 8:
[0122] A method for preparing an F-doped Ni3S2 bifunctional self-supporting electrocatalyst using a supersaturated NH4F solution, comprising the following steps:
[0123] Step 1: Using nickel foam with dimensions of 2cm*4cm, a thickness of 3.0mm, and a porosity of 75ppi as the nickel source, immerse it in 10mL of 1mol L⁻¹ nickel solution. -1 The samples were ultrasonically cleaned for 25 minutes each in dilute sulfuric acid solution, deionized water, and anhydrous ethanol, and then air-dried at room temperature.
[0124] Step 2: Disperse 0.4g of thioacetamide and 0.3g of urea in 40mL of deionized water, add a magnetic stir bar and stir for 40 minutes to obtain a colorless and transparent solution.
[0125] Step 3: Place the cleaned nickel foam from Step 1 and the solution prepared in Step 2 into a reactor lined with para-polystyrene. Heat the reactor to 200°C in an oven for a closed hydrothermal reaction for 12 hours, and then cool it to room temperature with a forced airflow.
[0126] Step 4: Remove the sample from the hydrothermal reaction in Step 3 from the reactor, wash it with deionized water and anhydrous ethanol in small amounts several times, and then set it aside for later use to obtain the Ni3S2 substrate.
[0127] Step 5: Disperse 3g of NH4F in 5mL of deionized water and sonicate for 3 minutes to obtain a supersaturated solution.
[0128] Step 6: Immerse the Ni3S2 prepared in Step 4 in the supersaturated NH4F solution prepared in Step 5 in a 50mL beaker and soak at room temperature for 20 minutes.
[0129] Step 7: Place the sample soaked in Step 6 into a corundum ark and heat it at 300°C for 10 minutes in a fume hood.
[0130] Step 8: Remove the electrocatalyst that was heat-treated in Step 7 from the boat, and wash it with deionized water and anhydrous ethanol in small amounts and multiple times to obtain the F-doped Ni3S2 bifunctional self-supporting electrocatalyst.
[0131] Example 9:
[0132] A method for preparing an F-doped Ni3S2 bifunctional self-supporting electrocatalyst using a supersaturated NH4F solution, comprising the following steps:
[0133] Step 1: Using nickel foam with dimensions of 2cm*4cm, a thickness of 3.0mm, and a porosity of 75ppi as the nickel source, immerse it in 10mL of 1mol L⁻¹ nickel solution. -1 The samples were ultrasonically cleaned for 25 minutes each in dilute sulfuric acid solution, deionized water, and anhydrous ethanol, and then air-dried at room temperature.
[0134] Step 2: Disperse 0.4g of thioacetamide and 0.3g of urea in 40mL of deionized water, add a magnetic stir bar and stir for 40 minutes to obtain a colorless and transparent solution.
[0135] Step 3: Place the cleaned nickel foam from Step 1 and the solution prepared in Step 2 into a reactor lined with para-polystyrene. Heat the reactor to 200°C in an oven for a closed hydrothermal reaction for 12 hours, and then cool it to room temperature with a forced airflow.
[0136] Step 4: Remove the sample from the hydrothermal reaction in Step 3 from the reactor, wash it with deionized water and anhydrous ethanol in small amounts several times, and then set it aside for later use to obtain the Ni3S2 substrate.
[0137] Step 5: Disperse 3g of NH4F in 8mL of deionized water and sonicate for 3 minutes to obtain a supersaturated solution.
[0138] Step 6: Immerse the Ni3S2 prepared in Step 4 in the supersaturated NH4F solution prepared in Step 5 in a 50mL beaker and soak at room temperature for 20 minutes.
[0139] Step 7: Place the sample soaked in Step 6 into a corundum ark and heat it at 300°C for 10 minutes in a fume hood.
[0140] Step 8: Remove the electrocatalyst that was heat-treated in Step 7 from the boat, and wash it with deionized water and anhydrous ethanol in small amounts and multiple times to obtain the F-doped Ni3S2 bifunctional self-supporting electrocatalyst.
[0141] Example 10:
[0142] A method for preparing an F-doped Ni3S2 bifunctional self-supporting electrocatalyst using a supersaturated NH4F solution, comprising the following steps:
[0143] Step 1: Using nickel foam with dimensions of 2cm*4cm, a thickness of 1.5mm, and a porosity of 75ppi as the nickel source, immerse it in 10mL of 1mol L⁻¹ solution. -1 The samples were ultrasonically cleaned for 25 minutes each in dilute sulfuric acid solution, deionized water, and anhydrous ethanol, and then air-dried at room temperature.
[0144] Step 2: Disperse 0.4g of thioacetamide and 0.3g of urea in 40mL of deionized water, add a magnetic stir bar and stir for 40 minutes to obtain a colorless and transparent solution.
[0145] Step 3: Place the cleaned nickel foam from Step 1 and the solution prepared in Step 2 into a reactor lined with para-polystyrene. Heat the reactor to 200°C in an oven for a closed hydrothermal reaction for 12 hours, and then cool it to room temperature with a forced airflow.
[0146] Step 4: Remove the sample from the hydrothermal reaction in Step 3 from the reactor, wash it with deionized water and anhydrous ethanol in small amounts several times, and then set it aside for later use to obtain the Ni3S2 substrate.
[0147] Step 5: Disperse 3g of NH4F in 2mL of deionized water and sonicate for 3 minutes to obtain a supersaturated solution.
[0148] Step 6: Immerse the Ni3S2 prepared in Step 4 in the supersaturated NH4F solution prepared in Step 5 in a 50mL beaker and soak at room temperature for 20 minutes.
[0149] Step 7: Place the sample soaked in Step 6 into a corundum ark and heat it at 300°C for 10 minutes in a fume hood.
[0150] Step 8: Remove the electrocatalyst that was heat-treated in Step 7 from the boat, and wash it with deionized water and anhydrous ethanol in small amounts and multiple times to obtain the F-doped Ni3S2 bifunctional self-supporting electrocatalyst.
[0151] Example 11:
[0152] The other steps are the same as in Example 1, except that "20 minutes" in "soaking at room temperature for 20 minutes" is changed to "300 minutes".
[0153] Example 12:
[0154] The other steps are the same as in Example 1, except that "2 mL" in "3 g NH4F dispersed in 2 mL deionized water" is changed to "8.8 mL".
[0155] Example 13:
[0156] The other steps are the same as in Example 1, except that "300°C" in "heat at 300°C for 10 minutes on an electric furnace" is changed to "800°C".
[0157] Example 14:
[0158] The other steps are the same as in Example 1, except that "40 minutes" in "heating at 300°C on an electric furnace for 10 minutes" is changed to "240 minutes".
[0159] Example 15:
[0160] The other steps are the same as in Example 1, except that "electric furnace" in "heat at 300°C for 10 minutes on an electric furnace" is replaced with "electric heating mantle".
[0161] Example 16:
[0162] The other steps are the same as in Example 1, except that "electric furnace" in "heat at 300°C for 10 minutes" is replaced with "oil bath".
[0163] Example 17:
[0164] The other steps are the same as in Example 1, except that "electric furnace" in "heat at 300°C for 10 minutes on an electric furnace" is replaced with "tube furnace".
[0165] Example 18:
[0166] The other steps are the same as in Example 1, except that "200°C" in "heating to 200°C in an oven for a closed hydrothermal reaction for 12 hours" is changed to "180°C".
[0167] Example 19:
[0168] The other steps are the same as in Example 1, except that "200°C" in "heating to 200°C in an oven for a closed hydrothermal reaction for 12 hours" is changed to "220°C".
[0169] This invention is not limited to the specific embodiments described above. Those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of this invention.
[0170] Based on the comparison of the above examples, the following conclusions can be drawn from the data results:
[0171] (1) The soaking time of Ni3S2 substrate (20min, 40min, 60min, 80min, 300min) had no significant effect on the performance and morphology of the sample;
[0172] (2) The soaking water content of Ni3S2 substrate (2mL, 5mL, 8mL) had no significant effect on the performance and morphology of the sample;
[0173] (3) The OER performance gradually increased with heating time on the electric furnace (10 min, 30 min, 50 min, 70 min, 240 min) (see...). Figure 10 HER performance shows a downward trend (see) Figure 11 Since the OER plays a decisive role in the total electrolysis, the optimal conditions are determined under the condition where the OER performance is at its best;
[0174] (4) The thickness of the nickel foam (1.5 mm, 3 mm) showed better performance than other experimental methods when using a 1.5 mm thickness, and the performance improvement was even more significant when using a 3 mm thickness of nickel foam (see...). Figure 12 ).
[0175] Matters not covered in this invention are common knowledge.
Claims
1. The application of an F-doped Ni3S2 bifunctional self-supporting electrocatalyst in the whole water electrolysis process, characterized in that, The catalyst uses the three-dimensional porous structure of nickel foam as a self-supporting framework. Ni3S2 is constructed in situ on the surface of its pores, and then F-doped Ni3S2 nanoarrays are synthesized by acid etching. The thickness of the array is 2.5 mm to 3.5 mm. The ratio of Ni to S atoms is 3:2, and the F doping amount is 2% to 30%. The surface morphology of the nanoarray is a cylindrical rod with a length of 1 to 5 μm and a diameter of 0.2 to 1.2 μm. F, Ni and S elements are uniformly distributed on the surface. The preparation method of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst includes the following steps: Step 1: The nickel foam is ultrasonically treated in dilute sulfuric acid solution, deionized water and anhydrous ethanol in sequence, and then dried at room temperature; Step 2: Disperse thioacetamide and urea in deionized water and stir magnetically for 0.5 to 2.5 hours to obtain a colorless and transparent solution; Add 0.1 g to 0.5 g of thioacetamide and 0.2 g to 0.5 g of urea to every 30 ml to 50 ml of deionized water; Step 3: Place the cleaned nickel foam from Step 1 and the solution prepared in Step 2 into a reaction vessel lined with para-polystyrene (PPL), and perform a hydrothermal reaction at 160℃ ~ 240℃ for 8 to 16 hours, followed by forced air cooling to room temperature; after cleaning, a Ni3S2 substrate loaded on nickel foam is obtained. Step 4: Immerse the Ni3S2 substrate obtained in the previous step in a supersaturated solution of NH4F for 10 minutes to 400 minutes to obtain the Ni3S2 wetted state; In the case of a supersaturated NH4F solution, 2 to 6 g of NH4F is added to every 1 to 10 mL of deionized water. Step 5: Place the Ni3S2 wetted state obtained in the previous step into a boat and heat it at 200 ~ 1000℃ for 10 ~ 500 minutes to obtain F-doped Ni3S2 bifunctional self-supporting electrocatalyst.
2. The application of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst as described in claim 1 in the whole water electrolysis process, characterized in that, In the preparation method, the nickel foam has a porosity of 50 ppi to 120 ppi and a thickness of 2.8 to 3.2 mm.
3. The application of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst as described in claim 1 in the whole water electrolysis process, characterized in that, In the preparation method, the concentration of the dilute sulfuric acid is 0.1 mol·L⁻¹. -1 ~ 2 mol·L -1 The ultrasonic treatment time is 10 to 30 minutes.
4. The application of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst as described in claim 1 in the whole water electrolysis process, characterized in that, In the preparation method, the purity of the anhydrous ethanol is 99.7%.
5. The application of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst as described in claim 1 in the whole water electrolysis process, characterized in that, In the preparation method, the ark is made of corundum.
6. The application of the F-doped Ni3S2 bifunctional self-supporting electrocatalyst as described in claim 1 in the whole water electrolysis process, characterized in that, In specific applications, a three-electrode system is used, with the working electrode being an F-doped Ni3S2 bifunctional self-supporting electrocatalyst, the counter electrode being a carbon rod, and the reference electrode being a saturated calomel electrode, to perform electrolytic catalytic hydrogen and oxygen production. The alkaline electrolyte is 0.1 mol·L⁻¹. -1 ~ 2 mol·L -1 KOH solution; Electrolysis is performed at a constant voltage, with a voltage range of 1.5 V to 1.8 V.