Preparation method of high-activity electrolytic water catalyst
By electrodepositing NiCo-LDH precursors on nickel foam and calcining them to form NiCoP catalysts, the problems of low activity and high cost of noble metal-based electrocatalysts are solved, achieving efficient water electrolysis for hydrogen production and urea wastewater treatment, with excellent electrocatalytic performance and stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEILONGJIANG UNIVERSITY OF SCIENCE AND TECHNOLOGY
- Filing Date
- 2025-01-07
- Publication Date
- 2026-07-21
Smart Images
Figure CN119800427B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst preparation for hydrogen production by water electrolysis, and specifically to a method for preparing a nickel-cobalt phosphide-based alkaline water electrolysis catalyst. Background Technology
[0002] Hydrogen (H2), as a high-heat-density and environmentally friendly fuel, has been regarded as one of the alternative resources to traditional fossil fuels and has broad application prospects. Electrocatalytic hydrogen production from urea wastewater can not only achieve efficient hydrogen production but also effectively treat urea wastewater. UOR (Ultra-Organic Reaction) is a six-electron transfer process in an alkaline medium, requiring a highly efficient catalyst to drive and lower the reaction energy barrier. Initially, some noble metal-based electrocatalysts, such as Pt, Ir, and Ru, exhibited ideal activity and low onset potentials in HER and UOR. However, their scarcity and high cost have hindered their widespread application. Summary of the Invention
[0003] In order to overcome the technical problems of low reactivity, high cost and complex preparation methods of hydrogen production catalysts in the prior art, this invention provides a method for preparing a highly active water electrolysis catalyst.
[0004] A method for preparing a highly active water electrolysis catalyst, specifically comprising the following steps:
[0005] 1. Cut the nickel foam, then ultrasonically wash it, then soak it in dilute hydrochloric acid for 18-22 seconds, and then dry it after cleaning.
[0006] II. Synthesis of NiCo-LDH precursor by electrodeposition method;
[0007] The three electrodes were placed in a homogeneous solution of nickel and cobalt salts, with the nickel foam treated in step one as the working electrode, Ag / AgCl as the reference electrode, and platinum as the counter electrode. A constant voltage was applied for electrodeposition, followed by washing and drying to obtain a dark green nickel foam NiCo-LDH precursor.
[0008] 3. NaH2PO2 and the NiCo-LDH precursor obtained in step 2 are calcined in an argon atmosphere and then cooled to room temperature to obtain a highly active water electrolysis catalyst.
[0009] Due to the synergistic effect of bimetals, Ni-Co bimetallic compounds can have high HER catalytic activity. This invention adds a specific amount of exogenous phosphorus and oxygen to produce bimetallic phosphates, which can significantly improve the activity and stability of electrocatalysts by effectively changing the electronic state of their active sites.
[0010] This catalyst has high reactivity and low cost. At the same time, its preparation method is simple, and it can also solve the problem of urea pollution, reduce the energy consumption of hydrogen production, and treat urea wastewater.
[0011] Beneficial effects of this invention:
[0012] 1. This catalyst is a NiCoP self-supporting electrode, which can efficiently electrolyze urea wastewater to produce hydrogen. The petal-shaped nanosheet structure with abundant defect surfaces was prepared by electrodeposition and high-temperature phosphating, which has excellent electrocatalytic performance and stability.
[0013] 2. NiCoP at 10 mA cm -2 At a current density of 80 mV, the enhanced performance of HER was determined by a low overpotential of 80 mV, which reduced the hydrogen production efficiency.
[0014] 3. The preparation process of this invention is simple and controllable, the raw material cost is low, the catalyst performance is good, and it has the potential for industrial application.
[0015] This invention is used to prepare highly active water electrolysis catalysts. Attached Figure Description
[0016] Figure 1 SEM image of the highly active water electrolysis catalyst prepared in Example 1;
[0017] Figure 2 TEM image of the highly active water electrolysis catalyst prepared in Example 1;
[0018] Figure 3 The XRD pattern of the highly active water electrolysis catalyst prepared in Example 1 is shown below.
[0019] Figure 4 XPS image of the highly active water electrolysis catalyst prepared in Example 1;
[0020] Figure 5 HER test LSV curves of the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2;
[0021] Figure 6 The CV curve of the highly active water electrolysis catalyst prepared in Example 1 is shown.
[0022] Figure 7 EIS diagrams of the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2;
[0023] Figure 8 The UOR test LSV curves of the catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2 for electrocatalytic decomposition of urea wastewater are shown.
[0024] Figure 9 The catalyst prepared in Example 1 was tested at 100 mA / cm². -1 Current density-time stability test curve measured at current density. Detailed Implementation
[0025] Specific Implementation Method 1: This implementation method provides a method for preparing a highly active water electrolysis catalyst, which is carried out according to the following steps:
[0026] 1. Cut the nickel foam, then ultrasonically wash it, then soak it in dilute hydrochloric acid for 18-22 seconds, and then dry it after cleaning.
[0027] II. Synthesis of NiCo-LDH precursor by electrodeposition method;
[0028] The three electrodes were placed in a homogeneous solution of nickel and cobalt salts, with the nickel foam treated in step one as the working electrode, Ag / AgCl as the reference electrode, and platinum as the counter electrode. A constant voltage was applied for electrodeposition, followed by washing and drying to obtain a dark green nickel foam NiCo-LDH precursor.
[0029] 3. NaH2PO2 and the NiCo-LDH precursor obtained in step 2 are calcined in an argon atmosphere and then cooled to room temperature to obtain a highly active water electrolysis catalyst.
[0030] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: in step one, the nickel foam is cut to a size of 1cm × 2cm. Everything else is the same as in Specific Implementation Method One.
[0031] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the ultrasonic cleaning in step 1 is as follows: The cut nickel foam is immersed in acetone solution and placed in an ultrasonic cleaner for 10 minutes, then cleaned with deionized water, ultrasonically treated in anhydrous ethanol for 15 minutes, and then washed three times with deionized water. Everything else is the same as in Specific Implementation Method 1 or 2.
[0032] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: the foamed nickel soaked in dilute hydrochloric acid in step one is repeatedly washed with deionized water, and the drying temperature is controlled at 50°C for vacuum drying. Everything else is the same as in Specific Implementation Methods One to Three.
[0033] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the nickel salt and cobalt salt solutions in step two are prepared using nickel nitrate hexahydrate and cobalt nitrate hexahydrate, wherein the concentration of nickel salt is 0.5 mol / L and the concentration of cobalt salt is 0.5 mol / L. Everything else is the same as in Specific Implementation Methods One to Four.
[0034] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the working voltage for electrodeposition in step two is -1V, and the deposition time is controlled to be 10 minutes. Everything else is the same as in Specific Implementation Methods One to Five.
[0035] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: step two washing uses deionized water, and the drying temperature is controlled at 60℃. Everything else is the same as in Specific Implementation Methods One to Six.
[0036] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the amount of NaH2PO2 used in step three is 0.1g. Everything else is the same as in Specific Implementation Methods One to Seven.
[0037] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that, in step three, NaH2PO2 and the NiCo-LDH precursor are placed in two independent positions on the precursor tubular furnace ceramic boat, with NaH2PO2 located upstream and the NiCo-LDH precursor located downstream. Everything else is the same as in Specific Implementation Methods One to Eight.
[0038] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: in step three, the argon flow rate is controlled at 20 mL / min, the heating rate is 5℃ / min, the temperature is raised to 300℃, and the calcination time is 2 hours. Everything else is the same as in Specific Implementation Methods One to Nine.
[0039] The scope of this invention is not limited to the above-described embodiments; a combination of one or more specific embodiments can also achieve the purpose of the invention.
[0040] Example 1:
[0041] This embodiment describes a method for preparing a highly active water electrolysis catalyst, which is carried out according to the following steps:
[0042] 1. Cut the nickel foam to a size of 1cm × 2cm. Then immerse the cut nickel foam in acetone solution and place it in an ultrasonic cleaner for 10 minutes. Then clean it with deionized water, then ultrasonically treat it in anhydrous ethanol for 15 minutes. Then wash it three times with deionized water, then soak it in dilute hydrochloric acid for 20 seconds. Then wash it repeatedly with deionized water and dry it under vacuum at a temperature of 50℃.
[0043] II. Synthesis of NiCo-LDH precursor by electrodeposition method;
[0044] The three electrodes were placed in a homogeneous solution of nickel and cobalt salts. The nickel and cobalt salt solutions were prepared using nickel nitrate hexahydrate and cobalt nitrate hexahydrate, with a nickel salt concentration of 0.5 mol / L and a cobalt salt concentration of 0.5 mol / L. The nickel foam treated in step one was used as the working electrode, Ag / AgCl as the reference electrode, and a platinum electrode as the counter electrode. A constant voltage was applied for electrodeposition, with the working voltage controlled at -1V and the deposition time at 10 min. The electrodes were then washed with deionized water and dried at 60℃ for 12 h to obtain a dark green nickel foam NiCo-LDH precursor.
[0045] 3. Place 0.1g NaH2PO2 and the NiCo-LDH precursor obtained in step 2 into two independent positions on a precursor tube furnace ceramic boat, with NaH2PO2 located upstream and the NiCo-LDH precursor located downstream. Calcination is carried out in an argon atmosphere, with the argon flow rate controlled at 20mL / min and the heating rate at 5℃ / min. The temperature is raised to 300℃ and the calcination time is 2h. Then, the mixture is cooled to room temperature to obtain a highly active water electrolysis catalyst (NiCoP).
[0046] Figure 1 SEM image of the highly active water electrolysis catalyst prepared in Example 1;
[0047] Figure 2 TEM image of the highly active water electrolysis catalyst prepared in Example 1;
[0048] pass Figure 1 and Figure 2 As can be seen, NiCoP exhibits a petal-like shape resembling nanosheets. The folds of the petals increase the specific surface area of NiCoP, exposing more active sites.
[0049] Figure 3 The XRD pattern of the highly active water electrolysis catalyst prepared in Example 1 is shown below.
[0050] X-ray diffraction (XRD) was used to analyze the crystal structure of the samples. NiCoP showed distinct characteristic peaks at 2θ = 41.0°, 44.8°, 47.5°, and 55.3°. These peaks can be attributed to the NiCoP (111), (201), (210), and (211) crystal planes. The matching of these peak positions indicates the synthesis of a NiCoP catalyst, consistent with the results from SEM and TEM.
[0051] Figure 4 XPS image of the highly active water electrolysis catalyst prepared in Example 1;
[0052] XPS studies were conducted to investigate the composition and chemical state of NiCoP. The overall spectrum showed that the NiCoP catalyst was doped with Ni, Co, and P elements.
[0053] Comparative Example 1:
[0054] A nickel phosphide water electrolysis catalyst is prepared by the following method:
[0055] (1) Add 1.45405g Ni(NO3)2·6H2O to 100mL of deionized water and stir for 10min to dissolve it completely; in a three-electrode system, use 30mL of 50mM(NO3)2·6H2O solution as electrolyte and perform constant voltage electrodeposition for 10min at a working voltage of -1V. After electrodeposition, layered double hydroxides are obtained. First, wash with deionized water and ethanol three times, and then dry at 60℃ for 12 hours. The obtained NiLDH / NF precursor is ready for use.
[0056] (2) A high-temperature phosphating method was adopted, using NaH2PO2 as the phosphorus source, and 0.1g of NaH2PO2 and the NiLDH / NF precursor obtained in the first step (1cm×2cm, effective area 1cm²) were added. 2 The catalyst was placed in two separate ceramic boats. The high-temperature resistant boat-shaped ceramic boat containing the phosphorus source was placed in the quartz tube of the heating zone of the tube furnace (5 cm upstream of the furnace plug). The ceramic boat containing the NiLDH / NF precursor obtained in step 1 was placed in the middle and lower reaches of the quartz tube of the tube furnace. Subsequently, the catalyst was heated to 300°C in an argon atmosphere and kept at a constant temperature for 2 hours (argon flow rate maintained at 20 mL / min). After cooling to room temperature, it was removed to obtain the nickel phosphide electrolysis catalyst (NiP).
[0057] Comparative Example 2:
[0058] A cobalt phosphide water electrolysis catalyst is prepared by the following method:
[0059] The difference between this comparative example and Comparative Example 1 is that in step 1, 1.45515g of Co(NO3)2·6H2O was used instead of 1.45405g of Ni(NO3)2·6H2O to prepare a cobalt phosphide electrolysis catalyst (CoP). Other processes and parameters are the same as in Comparative Example 1.
[0060] The products obtained in Examples 1 and 1 to 2 were used as catalysts in a solution containing 1 MkOH for water electrolysis HER testing. Electrochemical tests were performed on an electrochemical workstation (CHI760E) using a standard three-electrode system, with the Hg / HgO electrode as the reference electrode, the platinum sheet electrode as the counter electrode, and the products prepared in Examples 1 and 1 to 3 as the working electrode (geometric area 1 cm × 1 cm). Linear sweep voltammetry (LSV) was used at 5 mV / s. -1The scanning rate was measured, and the potential of the reversible hydrogen electrode (RHE) was calculated using the formula Evs.RHE=Evs.Hg / HgO+0.059×Ph+0.098. This was done at a current density of 100mAcm. -2 Under the specified conditions, the electrochemical stability was tested using long-term chronoamperometry curves.
[0061] The results are shown in the figure. Figure 5 The HER test LSV curves for the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2 show that the NiCoP electrocatalytic electrode has the lowest overpotential, and the η10 of NiCo(PO4)x (producing 10 mA cm⁻¹) is the lowest. -2 The potential of the electrode is 80mV, which is better than that of NiP (137mV) and CoP (122mV).
[0062] Figure 7 The EIS diagrams of the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2 show that the resistance of the NiCoP electrode (5.89Ω) is smaller than that of NiP (11.23Ω) and CoP (7.92Ω), therefore, the charge transfer rate of the NiCoP electrode is faster.
[0063] Figure 8 The LSV curves for the electrocatalytic decomposition of urea wastewater by the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2 are shown. The LSV curves indicate that NiCoP at 10 mA / cm²... -2 The UOR potential shown below (1.069V) is better than that of NiP (1.456V) and CoP (1.406V).
[0064] Figure 9 The catalyst prepared in Example 1 was tested at 100 mA / cm². -1 The current density-time stability test curve measured at the current density shows that NiCoP maintains an almost constant operating potential of 1.42V after stabilization, with almost no change after 72 hours of reaction.
[0065] In summary, this invention provides a highly active water electrolysis catalyst with a reasonable electron distribution and excellent intrinsic activity, capable of efficiently electrocatalyzing UOR and HER. This invention utilizes a simple electrodeposition followed by high-temperature phosphating method to form a petal-like nanosheet structure on nickel foam, simplifying the preparation process and improving the long-term stability of the catalyst.
Claims
1. A method for preparing a highly active water electrolysis catalyst, characterized in that... This method is specifically carried out in the following steps:
1. Cut the nickel foam, then ultrasonically wash it, then soak it in dilute hydrochloric acid for 18-22 seconds, and then dry it after cleaning. II. Synthesis of NiCo-LDH precursor by electrodeposition method; The three electrodes were placed in a homogeneous solution of nickel and cobalt salts, with the nickel foam treated in step one as the working electrode, Ag / AgCl as the reference electrode, and platinum as the counter electrode. A constant voltage was applied for electrodeposition, followed by washing and drying to obtain a dark green nickel foam NiCo-LDH precursor.
3. NaH2PO2 and the NiCo-LDH precursor obtained in step 2 are calcined in an argon atmosphere and then cooled to room temperature to obtain a highly active water electrolysis catalyst. The nickel salt and cobalt salt solutions mentioned in step two are prepared using nickel nitrate hexahydrate and cobalt nitrate hexahydrate, wherein the concentration of nickel salt is 0.5 mol / L and the concentration of cobalt salt is 0.5 mol / L. The electrodeposition voltage in step two is -1V, and the deposition time is controlled at 10min.
2. The method for preparing a highly active water electrolysis catalyst according to claim 1, characterized in that... Step 1: Cut the nickel foam to a size of 1cm × 2cm.
3. The method for preparing a highly active water electrolysis catalyst according to claim 1, characterized in that... The ultrasonic cleaning in step one is as follows: Immerse the cut nickel foam in acetone solution and place it in an ultrasonic cleaner for 10 minutes, then clean it with deionized water, then ultrasonically treat it in anhydrous ethanol for 15 minutes, and then wash it with deionized water 3 times.
4. The method for preparing a highly active water electrolysis catalyst according to claim 1, characterized in that... Step 1: After soaking in dilute hydrochloric acid, the foamed nickel is repeatedly washed with deionized water and dried under vacuum at a controlled drying temperature of 50°C.
5. The method for preparing a highly active water electrolysis catalyst according to claim 1, characterized in that... Step two involves washing with deionized water and drying at a temperature of 60°C.
6. The method for preparing a highly active water electrolysis catalyst according to claim 1, characterized in that... In step three, the amount of NaH2PO2 used is 0.1g.
7. The method for preparing a highly active water electrolysis catalyst according to claim 1, characterized in that... Step 3: Place NaH2PO2 and NiCo-LDH precursor into two separate positions on the ceramic boat of the tubular furnace, with NaH2PO2 located upstream and NiCo-LDH precursor located downstream.
8. The method for preparing a highly active water electrolysis catalyst according to claim 1, characterized in that... Step 3: Control the argon flow rate to 20 mL / min, the heating rate to 5 °C / min, and heat to 300 °C for 2 hours.