Amorphous nickel-iron tungstate catalytic material and preparation method and application thereof
Patent Information
- Application Number
- CN202310247236.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-15
- Publication Date
- 2026-09-11
- Estimated Expiration
- 2043-03-15
AI Technical Summary
[0004]针对现有的电化学催化剂存在本征活性低，稳定性差等缺陷，本发明的第一个目的是在于提供一种具有球形颗粒结构，本征活性高，且稳定性好的非晶的钨酸镍铁催化材料
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Figure CN116180107B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrochemical catalysts, and specifically relates to an amorphous nickel-iron tungstate catalytic material, its preparation method, and its application. Background Technology
[0002] Electrochemical water splitting is a promising method for hydrogen production that could alleviate the energy crisis. The electrochemical water splitting process is strongly constrained by one of its half-reactions, the oxygen evolution reaction (OER), which utilizes a slow four-electron transfer mechanism. To date, noble metals ruthenium, iridium, and their oxides have proven to be state-of-the-art OER electrocatalysts. However, their instability under alkaline conditions, rarity, and high cost limit their industrial application. To meet the demands of large-scale applications, it is necessary to explore alternative catalysts with acceptable cost, activity, and durability.
[0003] Nickel tungstate, as a material with a wolframite structure, possesses many interesting properties, including good electrical conductivity and high structural durability. Due to these capabilities, this compound has been used in various applications, such as supercapacitors and batteries, as well as photocatalysis for water purification. Its high structural stability and good conductivity make it a promising candidate material for electrocatalysts. According to the literature, due to the similar crystal structures of all members of transition metal tungstates, other metals are often introduced to improve electrocatalytic performance. However, the effect of iron introduction on the electrochemical reconstruction behavior and electrocatalytic performance of nickel tungstate has not been studied. Therefore, introducing Fe into nickel tungstate to reduce its crystallinity, promote its reconstruction process, and improve its electrocatalytic activity is a topic worthy of further investigation. Summary of the Invention
[0004] In view of the shortcomings of existing electrochemical catalysts, such as low intrinsic activity and poor stability, the first objective of this invention is to provide an amorphous nickel-iron tungstate catalyst material with a spherical particle structure, high intrinsic activity, and good stability.
[0005] The second objective of this invention is to provide a simple and low-cost method for preparing the amorphous nickel-iron tungstate catalyst.
[0006] The third objective of this invention is to provide an application of an amorphous nickel-iron tungstate catalytic material in electrochemistry, which has the characteristics of high intrinsic activity, good catalytic performance, and high stability.
[0007] To achieve the above-mentioned technical objectives, the present invention provides an amorphous nickel-iron tungstate catalytic material, wherein the chemical formula of the nickel-iron tungstate catalytic material is Fe. x Ni y WO4, wherein the molar ratio of Ni:Fe:W is 1:0.5 to 1.5:1.
[0008] The nickel-iron tungstate catalyst provided by this invention has a molar ratio of Ni:Fe:W = 1:0.5 to 1.5:1. When the molar ratio is within the above range, the resulting nickel-iron tungstate catalyst is amorphous. However, the inventors unexpectedly discovered that when the nickel-iron tungstate catalyst is amorphous, its electrocatalytic performance is significantly better than that of crystalline nickel-iron tungstate.
[0009] In a preferred embodiment, the nickel-iron tungstate catalyst has a molar ratio of Ni:Fe:W = 1:0.5 to 1:1.
[0010] In a further preferred embodiment, the nickel-iron tungstate catalyst has a molar ratio of Ni:Fe:W = 1:0.5:1.
[0011] The amorphous nickel-iron tungstate catalyst of the present invention exhibits optimal electrocatalytic performance when the molar ratio of nickel, iron and tungsten is 1:0.5:1.
[0012] In a preferred embodiment, the nickel-iron tungstate catalyst has a spherical particle structure. The inventors have discovered that the spherical particle structure can improve the intrinsic activity and stability of the catalyst.
[0013] In a preferred embodiment, the nickel-iron tungstate catalyst is composed of a mixture of two binary metal oxides, nickel tungstate and ferrous tungstate.
[0014] The present invention also provides a method for preparing an amorphous nickel-iron tungstate catalyst, wherein a nickel source, an iron source and a tungsten source are dissolved in water and stirred to obtain a suspension liquid. The suspension liquid is subjected to a hydrothermal reaction, and the solid and liquid are separated. The obtained solid phase is the nickel-iron tungstate catalyst. In the suspension liquid, Ni:Fe:W = 1:0.5 to 1.5:1.
[0015] The preparation process of this invention only requires strict control of the molar ratio of Ni, Fe, and W in the suspended liquid, and a spherical nickel-iron tungstate catalyst material can be obtained through a one-step hydrothermal method.
[0016] In a preferred embodiment, the nickel source is nickel nitrate hexahydrate (Ni(NO3)2·6H2O), the iron source is ferric nitrate nonahydrate (Fe(NO3)3·9H2O), and the tungsten source is sodium tungstate dihydrate (Na2WO4·2H2O).
[0017] In a preferred embodiment, nickel source, iron source and tungsten source are dissolved in an aqueous solution and stirred for 30 to 45 minutes to obtain a suspension.
[0018] After stirring, the nickel source, iron source, and tungsten source can be fully dissolved and dispersed evenly.
[0019] In a preferred embodiment, the ratio of Ni:Fe:W in the suspended liquid is 1:0.5 to 1:1.
[0020] In a further preferred embodiment, the ratio of Ni:Fe:W in the suspended liquid is 1:0.5:1.
[0021] In a preferred embodiment, the hydrothermal reaction temperature is 140–160°C, and the hydrothermal reaction time is 8–9 hours.
[0022] In actual operation, the solid-liquid separation process is as follows: after the hydrothermal reaction is completed, the solution is naturally cooled to room temperature; the supernatant solution is poured out to obtain the solid precipitate.
[0023] In a preferred embodiment, the obtained solid phase is washed sequentially with deionized water and ethanol, then centrifuged at 12000–15000 r / min for 3–4 min, dried in an oven at 60–80℃ for 8–9 h, and ground to obtain nickel iron tungstate catalyst material.
[0024] In actual operation, the obtained solid precipitate is washed three times each with deionized water and ethanol in turn. Then, the centrifuge tube containing the precipitate is placed in an incubator and kept at 60-80°C for 8-9 hours in an air atmosphere. The powder obtained by grinding is the nickel iron tungstate catalyst material.
[0025] The present invention also provides an application of an amorphous nickel-iron tungstate catalytic material, wherein the nickel-iron tungstate catalytic material is used as an electrochemical catalyst.
[0026] During application, the working electrode requires the use of naphthol as a binder.
[0027] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:
[0028] 1) The nickel iron tungstate catalytic material of the present invention has the characteristics of good stability and high catalytic activity, and can be widely used as an electrochemical catalyst.
[0029] 2) The nickel iron tungstate catalytic material of the present invention has a special structure and high catalytic activity, which greatly reduces the cost of using catalytic materials.
[0030] 3) The nickel iron tungstate catalyst of the present invention can be prepared by hydrothermal method, which has the advantages of convenient preparation, simple operation and mass production. Attached Figure Description
[0031] Figure 1 The image shows the XRD pattern of the amorphous nickel-iron tungstate electrochemical catalytic material prepared in Example 1.
[0032] Figure 2 The image shows a SEM image of the amorphous nickel-iron tungstate electrochemical catalytic material prepared in Example 1.
[0033] Figure 3The image shows the XRD pattern of the amorphous nickel-iron tungstate electrochemical catalytic material prepared in Example 2.
[0034] Figure 4 The image shows the XRD pattern of the crystalline nickel-iron tungstate electrochemical catalytic material in Comparative Example 1.
[0035] Figure 5 The graph shows a comparison of polarization curves (LSV) for Examples 1, 2, and Comparative Example 1.
[0036] Figure 6 C is from Examples 1, 2, and Comparative Example 1. dl Comparison chart.
[0037] Figure 7 This is a comparison of the normalized polarization curves of the electrochemical active area (ECSA) of Examples 1, 2, and Comparative Example 1.
[0038] Figure 8 The stability test curves are for Examples 1, 2, and Comparative Example 1. Detailed Implementation
[0039] The present invention will be further described in detail below with reference to specific, non-limiting embodiments.
[0040] All reagents used in the embodiments of this invention are commercially available.
[0041] Example 1
[0042] I. Preparation of Suspension Liquids:
[0043] According to the molar ratio of Ni:Fe:W = 1:0.5:1, 436.2 mg of nickel nitrate hexahydrate, 303 mg of ferric nitrate nonahydrate and 494.8 mg of sodium tungstate dihydrate were weighed and dissolved in 45 mL of aqueous solution. The solution was stirred for 45 min to ensure complete dissolution and obtain a suspension (sonication may be appropriate).
[0044] II. Sediment
[0045] Pour the suspension obtained in step one into an autoclave, place it in an insulated box and heat it to 140°C for 8 hours, then let it cool naturally to room temperature; pour out the supernatant solution to obtain the precipitate.
[0046] III. Washing and Drying
[0047] The precipitate obtained in step two was washed three times each with deionized water and ethanol in turn. After centrifugation at 12000 r / min for 4 min, it was dried in an oven at 60℃ for 8 h. After grinding, powdered nickel iron tungstate catalyst material was obtained.
[0048] Figure 1The image shows the XRD pattern of the nickel-iron tungstate catalyst prepared in Example 1. It can be seen from the image that it has a wide range of properties and a low diffraction peak intensity, which is a result of the amorphous structure, indicating that the nickel-iron tungstate catalyst obtained in Example 1 is an amorphous nickel-iron tungstate catalyst.
[0049] Figure 2 The image shows an SEM image of the amorphous nickel-iron tungstate catalyst prepared in Example 1. As can be seen from the image, the obtained nickel-iron tungstate catalyst has a spherical particle structure.
[0050] IV. Electrocatalytic performance testing
[0051] Take 5 mg of the prepared powder and disperse it in a mixed solution containing 30 μl Nafion and 470 μl ethanol. After sonication for 45 min, take 100 μl of the mixed solution and drop it onto the treated nickel foam. After natural drying, use an electrochemical workstation to measure the electrochemical performance of the catalyst. The above-obtained powder is used as the working electrode, the saturated Ag / AgCl electrode is used as the reference electrode, the platinum sheet is used as the counter electrode, and 1.0 M KOH is used for electrolysis.
[0052] like Figure 5 As shown in the LSV curve, when the current density reaches 10 mA cm⁻¹ -2 At this point, an overpotential of 262mV is required, indicating relatively high OER activity.
[0053] like Figure 6 C dl As shown in the comparison diagram, C in Example 1 dl The value reached 6.03 mFcm -2 The comparison shows that it has a relatively high electrochemical active area.
[0054] like Figure 7 The comparison of the electrochemical active area (ECSA) normalized polarization curves shows that Example 1 has superior intrinsic activity.
[0055] like Figure 8 As shown in the stability test curves, Example 1 can maintain a stable potential for over 50 hours with almost imperceptible voltage changes at a current density of 50 mA cm⁻². The polarization curves before and after the durability test are shown below. Figure 8 As shown in the illustration, the activity decreased only slightly after the experiment.
[0056] Example 2
[0057] I. Preparation of Suspension Liquids:
[0058] According to the molar ratio of Ni:Fe:W = 1:1:1, 436.2 mg of nickel nitrate hexahydrate, 606 mg of ferric nitrate nonahydrate and 494.8 mg of sodium tungstate dihydrate were weighed and dissolved in 45 mL of aqueous solution. The solution was stirred for 45 min to ensure complete dissolution and obtain a suspension (sonication may be appropriate).
[0059] II. Sediment
[0060] Pour the suspension obtained in step one into an autoclave, place it in an insulated box and heat it to 140°C for 8 hours, then let it cool naturally to room temperature; pour out the supernatant solution to obtain the precipitate.
[0061] III. Washing and Drying
[0062] The precipitate obtained in step two was washed three times each with deionized water and ethanol in turn. After centrifugation at 12000 r / min for 4 min, it was dried in an oven at 60℃ for 8 h. After grinding, powdered nickel iron tungstate catalyst material was obtained.
[0063] Figure 3 The image shows the XRD pattern of the nickel-iron tungstate catalyst prepared in Example 2. It can be seen from the image that it has a wide range of properties and a low diffraction peak intensity, which is a result of the amorphous structure, indicating that the nickel-iron tungstate catalyst obtained in Example 2 is an amorphous catalyst.
[0064] IV. Electrocatalytic performance testing
[0065] Take 5 mg of the prepared powder and disperse it in a mixed solution containing 30 μl Nafion and 470 μl ethanol. After sonication for 45 min, take 100 μl of the mixed solution and drop it onto the treated nickel foam. After natural drying, use an electrochemical workstation to measure the electrochemical performance of the catalyst. The above-obtained powder is used as the working electrode, the saturated Ag / AgCl electrode is used as the reference electrode, the platinum sheet is used as the counter electrode, and 1.0 M KOH is used for electrolysis.
[0066] like Figure 5 As shown in the LSV curve, when the current density reaches 10 mA cm⁻¹ -2 When the overpotential is 265mV, it indicates that it has relatively high OER activity.
[0067] like Figure 6 C dl As shown in the comparison diagram, C in Example 2 dl The value reached 5.09 mF cm -2 The comparison shows that it has a relatively high electrochemical active area.
[0068] like Figure 7 The comparison of the electrochemical active area (ECSA) normalized polarization curves shows that Example 2 has relatively superior intrinsic activity.
[0069] Comparative Example 1
[0070] I. Preparation of Suspension Liquids:
[0071] According to the molar ratio of Ni:Fe:W = 1:2:1, 436.2 mg of nickel nitrate hexahydrate, 1212 mg of ferric nitrate nonahydrate and 494.8 mg of sodium tungstate dihydrate were weighed and dissolved in 45 mL of aqueous solution. The solution was stirred for 45 min to ensure complete dissolution and obtain a suspension (sonication for 5-10 min may be appropriate).
[0072] II. Sediment
[0073] Pour the suspension obtained in step one into an autoclave, place it in an insulated box and heat it to 140°C for 8 hours, then let it cool naturally to room temperature; pour out the supernatant solution to obtain the precipitate.
[0074] III. Washing and Drying
[0075] The precipitate obtained in step two was washed three times each with deionized water and ethanol in turn. After centrifugation at 12000 r / min for 4 min, it was dried in an oven at 60℃ for 8 h. After grinding, powdered nickel iron tungstate catalyst material was obtained.
[0076] Figure 4 The image shows the XRD pattern of the crystalline nickel-iron tungstate electrochemical catalyst in Comparative Example 1. The XRD pattern shows distinct crystal peaks for nickel tungstate and ferrous tungstate, indicating a crystalline structure.
[0077] IV. Electrocatalytic performance testing
[0078] Take 5 mg of the prepared powder and disperse it in a mixed solution containing 30 μl Nafion and 470 μl ethanol. After sonication for 45 min, take 100 μl of the mixed solution and drop it onto the treated nickel foam. After natural drying, use an electrochemical workstation to measure the electrochemical performance of the catalyst. The above-obtained powder is used as the working electrode, the saturated Ag / AgCl electrode is used as the reference electrode, the platinum sheet is used as the counter electrode, and 1.0 M KOH is used for electrolysis.
[0079] like Figure 5 As shown in the LSV curve, when the current density reaches 10 mA cm⁻¹ -2 At this point, an overpotential of 272mV is required, indicating that it has relatively low OER activity.
[0080] like Figure 6 C dl As shown in the comparison diagram, C in Example 1 dl The value reached 5.06 mFcm -2 The comparison shows that it has a relatively low electrochemical active area.
[0081] like Figure 7 The comparison of the electrochemical active area (ECSA) normalized polarization curves shows that Example 1 has relatively low intrinsic activity.
Claims
1. A method for preparing an amorphous nickel-iron tungstate catalytic material, characterized in that: Nickel source, iron source and tungsten source are dissolved in water and stirred to obtain a suspension. The suspension is subjected to a hydrothermal reaction and solid-liquid separation. The obtained solid phase is nickel iron tungstate catalyst material. The hydrothermal reaction temperature is 140~160℃ and the hydrothermal reaction time is 8~9 h. The chemical formula of the nickel-iron tungstate catalyst is Fe. x Ni y In the nickel-iron tungstate catalyst material WO4, the molar ratio of Ni:Fe:W is 1:0.5~1:1; The nickel-iron tungstate catalyst material has a spherical particle structure.
2. The method for preparing an amorphous nickel-iron tungstate catalytic material according to claim 1, characterized in that: The nickel source is nickel nitrate hexahydrate, the iron source is ferric nitrate nonahydrate, and the tungsten source is sodium tungstate dihydrate; Nickel, iron, and tungsten sources are dissolved in an aqueous solution and stirred for 30-45 minutes to obtain a suspension.
3. The method for preparing an amorphous nickel-iron tungstate catalytic material according to claim 1 or 2, characterized in that: The obtained solid phase was washed with deionized water and ethanol in turn, then centrifuged at 12000~15000 r / min for 3~4 min, dried in an oven at 60~80℃ for 8~9 h, and ground to obtain nickel iron tungstate catalyst material.
4. A method for preparing an amorphous nickel-iron tungstate catalytic material according to claim 1 or 2, characterized in that: The nickel-iron tungstate catalyst is composed of a mixture of two binary metal oxides, nickel tungstate and ferrous tungstate.
5. The application of an amorphous nickel-iron tungstate catalytic material prepared by the preparation method according to any one of claims 1-4, characterized in that: The nickel-iron tungstate catalyst was used as an oxygen evolution electrochemical catalyst for the electrochemical splitting of water.