An organic small molecule modified iron-nickel layered double hydroxide catalyst, a preparation method and application thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN UNIV
- Filing Date
- 2026-06-16
- Publication Date
- 2026-08-07
AI Technical Summary
[0003]本发明是要解决现有的电解海水制氢催化剂依赖贵金属、稳定性差的技术问题，而提供一种有机小分子修饰的铁镍层状双氢氧化物催化剂及其制备方法和应用，本发明利用简易一步电沉积法制备有机小分子修饰的NiFe层状双氢氧化物催化剂，该催化剂将环己甲酸、1,4-环己二甲酸、1,3,5-环己三酸、苯甲酸、对苯二甲酸、均苯三甲酸等有机小分子锚定在NiFe层状双氢氧化物上，用于电解海水制氢，在碱性海水的条件下实现了超过2500小时的稳定性
[0015]本发明的有机小分子修饰的铁镍层状双氢氧化物催化剂，由于层间含有有机小分子，能够锚定催化剂中的金属离子，从而提高催化剂的性能与稳定性。本发明的有机小分子修饰的铁镍层状双氢氧化物催化剂在1 M KOH海水中，在10 mA cm-2的电流密度下，掺入有机小分子均苯三甲酸(TMA)的催化剂OER过电势仅为207 mV，并且以其作为阳极的电解槽在碱性海水中析氧反应稳定运行超2500小时，具备高活性和高稳定性的特点。本发明有机小分子修饰的铁镍层状双氢氧化物催化剂可用于工业电解海水制氢领域。
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Abstract
Description
Technical Field
[0001] This invention relates to binary NiFe layered double hydroxide electrocatalysts, their preparation methods, and applications, belonging to the fields of new energy materials technology and water electrolysis for hydrogen production. Background Technology
[0002] Hydrogen, as an environmentally friendly, abundant, and high-energy-density gaseous fuel and industrial feedstock, is a crucial driver of the development of hydrogen energy systems. Water electrolysis for hydrogen production, with its clean zero-carbon emission characteristics, is considered a key technology for replacing fossil fuels and meeting global sustainable energy demands. However, the large-scale commercial application of this technology still faces core challenges: current high-performance electrocatalysts heavily rely on precious metals such as iridium and ruthenium, or their oxides, directly leading to high costs for hydrogen production systems. Furthermore, the scarcity of these precious metals also constrains its sustainability. Moreover, water electrolysis for hydrogen production consumes large amounts of high-purity water, undoubtedly placing enormous pressure on freshwater resources. To address this issue, seawater electrolysis is gradually gaining attention. Seawater is one of the most abundant and sustainable water resources on Earth, considered a long-term reliable alternative. However, the complex chemical composition and high salinity of seawater present numerous challenges to the electrolysis process. For example, the abundant chloride ions (Cl-) in seawater... - The chlorine evolution reaction (CER) easily occurs at the anode, which not only reduces hydrogen yield but also leads to equipment corrosion and increased maintenance costs. Furthermore, local pH changes during seawater electrolysis can adversely affect the stability of electrode materials. Therefore, with the rapid development of the hydrogen energy industry, there is an urgent need to develop more cost-effective, higher-performance, and more stable high-efficiency catalyst materials, as well as innovative seawater electrolysis hydrogen production technologies, to promote its large-scale commercial application. Summary of the Invention
[0003] This invention aims to address the technical problems of existing seawater electrolysis hydrogen production catalysts, which rely on precious metals and suffer from poor stability. It provides an organic small molecule-modified iron-nickel layered double hydroxide catalyst, its preparation method, and its application. This invention utilizes a simple one-step electrodeposition method to prepare an organic small molecule-modified NiFe layered double hydroxide catalyst. This catalyst anchors organic small molecules such as cyclohexanecarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3,5-cyclohexanetriic acid, benzoic acid, terephthalic acid, and trimesopic acid onto the NiFe layered double hydroxide. When used for seawater electrolysis to produce hydrogen, it achieves stability exceeding 2500 hours under alkaline seawater conditions.
[0004] The organic small molecule modified iron-nickel layered double hydroxide catalyst of the present invention uses nickel foam as a substrate, and grows NiFe layered double hydroxide on the surface of nickel foam, and contains organic small molecules between the NiFe layered double hydroxide layers; wherein the organic small molecules are cyclohexanecarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3,5-cyclohexanetriic acid, benzoic acid (BA), terephthalic acid (TPA) or trimesophthalic acid (TMA).
[0005] The preparation method of the above-mentioned organic small molecule modified iron-nickel layered double hydroxide catalyst is carried out according to the following steps:
[0006] 1. The nickel foam is subjected to ultrasonic treatment in an organic solvent, dilute acid and anhydrous ethanol in sequence, and then cleaned with anhydrous ethanol and deionized water to obtain clean nickel foam.
[0007] 2. A precursor solution is prepared using Fe(NO3)3·9H2O, Ni(NO3)2·6H2O, and small organic molecules. Clean nickel foam is then placed in the precursor solution for electrodeposition. The applied voltage during electrodeposition is -0.5 to -2 V, and the electrodeposition time is 10 to 40 min. After the electrodeposition reaction is completed, the nickel foam is removed and cleaned to obtain nickel foam with organic small molecules embedded in the interlayer of NiFe layered double hydroxide. The organic small molecules are cyclohexanecarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3,5-cyclohexanetriic acid, benzoic acid (BA), terephthalic acid (TPA), or trimesophthalic acid (TMA).
[0008] 3. The foamed nickel with organic small molecules embedded in the interlayer of NiFe layered double hydroxide is dried to obtain an organic small molecule modified iron-nickel layered double hydroxide catalyst.
[0009] Preferably, the organic solvent mentioned in step one is one or more of methanol, acetone, isoacetone, and ethylene glycol.
[0010] Preferably, the dilute acid mentioned in step one is hydrochloric acid with a concentration of 5~14 mol / L.
[0011] Preferably, the molar ratio of Fe(NO3)3·9H2O to Ni(NO3)2·6H2O in the precursor solution in step two is 1:(0.2~5).
[0012] Preferably, the molar concentration of the organic small molecules in the precursor solution in step two is 0.01~2 mmol / mL.
[0013] Preferably, the drying in step three is natural drying or forced air drying at a temperature of 50~80℃ for 0.5~8 hours.
[0014] The application of the above-mentioned organic small molecule modified iron-nickel layered double hydroxide catalyst is characterized in that the application is to use the organic small molecule modified iron-nickel layered double hydroxide catalyst in the electrolysis of seawater to produce hydrogen.
[0015] The organic small molecule-modified iron-nickel layered double hydroxide catalyst of the present invention, due to the presence of organic small molecules in the interlayer, can anchor metal ions in the catalyst, thereby improving the catalyst's performance and stability. The organic small molecule-modified iron-nickel layered double hydroxide catalyst of the present invention, in 1 M KOH seawater, at 10 mA cm⁻¹... -2 At a given current density, the OER overpotential of the catalyst doped with the organic small molecule trimesolic acid (TMA) is only 207 mV, and the electrolyzer using it as the anode operates stably for over 2500 hours in alkaline seawater for the oxygen evolution reaction, exhibiting high activity and high stability. The organic small molecule modified iron-nickel layered double hydroxide catalyst of this invention can be used in the industrial electrolysis of seawater for hydrogen production. Attached Figure Description
[0016] Figure 1 SEM images of NiFe-LDH prepared in Example 2 at the 5 μm, 1 μm, and 500 nm scales;
[0017] Figure 2 SEM images of NiFe-LDH(BA) prepared in Example 3 at the 5 μm, 1 μm, and 500 nm scales;
[0018] Figure 3 SEM images of NiFe-LDH(TPA) prepared in Example 4 at the 5 μm, 1 μm, and 500 nm scales;
[0019] Figure 4 SEM images of NiFe-LDH(TMA) prepared in Example 1 at the 5 μm, 1 μm and 500 nm scales;
[0020] Figure 5 TEM and SAED images of NiFe-LDH prepared in Example 2;
[0021] Figure 6 TEM and SAED images of NiFe-LDH(TMA) prepared in Example 1;
[0022] Figure 7 X-ray diffraction patterns of NiFe-LDH(TMA), NiFe-LDH, NiFe-LDH(BA), and NiFe-LDH(TPA) prepared in Examples 1, 2, 3, and 4;
[0023] Figure 8The oxygen evolution polarization curves of NiFe-LDH(TMA), NiFe-LDH, NiFe-LDH(BA), and NiFe-LDH(TPA) prepared in Examples 1, 2, 3, and 4 in seawater are shown.
[0024] Figure 9 High-resolution XPS spectra of Fe 2p of NiFe-LDH (TMA) prepared in Example 1 and NiFe-LDH prepared in Example 2;
[0025] Figure 10 The NiFe-LDH(TMA) prepared in Example 1 was subjected to 1M KOH seawater and 500 mA cm⁻¹ -2 A graph showing the change of electric potential over time under constant current;
[0026] Figure 11 The polarization curves at 80°C are shown below, with NiFe-LDH (TMA) prepared in Example 1 and NiFe-LDH prepared in Example 2 as anodes, commercial NiMo as hydrogen evolution side catalyst assembled in an electrolyzer, and 1M KOH seawater as electrolyte.
[0027] Figure 12 The NiFe-LDH(TMA) prepared in Example 1 was used as the anode in 6M KOH seawater at 500 mA cm⁻¹ -2 A graph showing the change of electric potential over time under constant current. Detailed Implementation
[0028] The beneficial effects of the present invention will be verified using the following examples.
[0029] Example 1: The preparation method of the organic small molecule modified iron-nickel layered double hydroxide catalyst in this example is carried out according to the following steps:
[0030] 1. Cut the nickel foam into 1×2 cm pieces and then ultrasonically clean it in acetone, 6 M hydrochloric acid, and anhydrous ethanol for 10 minutes each. The hydrochloric acid is used to remove the oxide layer on the surface of the nickel foam, the acetone is used to degrease the nickel foam, and the anhydrous ethanol is used to remove the residual acetone and hydrochloric acid from the nickel foam. Then wash it with ethanol and deionized water. After cleaning, remove it to obtain clean nickel foam.
[0031] 2. Dissolve 6 mmol of Fe(NO3)2·9H2O and 4.5 mmol of Ni(NO3)2·6H2O in 20 mL of deionized water and stir for 30 min to obtain metal salt solution A; dissolve 0.5 mmol of trimesic acid (TMA) in 10 mL of N,N-dimethylformamide (DMF) and stir for 30 min to obtain small molecule solution B; mix metal salt solution A and small molecule solution B and stir for 30 min to obtain precursor solution; transfer precursor solution to electrolytic cell, immerse clean nickel foam in precursor solution, apply a voltage of -1.2 V for electrodeposition for 1600 s, after the reaction is complete, remove nickel foam and clean it to obtain nickel foam with organic small molecules embedded in the interlayer of NiFe layered double hydroxide;
[0032] 3. The nickel foam with organic small molecules embedded in the interlayer of NiFe layered double hydroxide was placed in a forced-air drying oven and dried at 80 ℃ for 40 min to obtain an iron-nickel layered double hydroxide catalyst modified with organic small molecule trimesic acid (TMA), denoted as NiFe-LDH(TMA).
[0033] Example 2: This comparative example is for preparing a NiFe layered double hydroxide catalyst without organic small molecules. The difference between this comparative example and Example 1 is that step two, "0.5 mmol of trimesolic acid (TMA)", is omitted. Other steps and parameters are the same as in Example 1, and a NiFe layered double hydroxide catalyst is obtained, which is denoted as NiFe-LDH.
[0034] Example 3: This comparative example is for preparing an iron-nickel layered double hydroxide catalyst modified with organic small molecule benzoic acid (BA). The difference between this comparative example and Example 1 is that "0.5 mmol of TMA" in step two is replaced with "0.5 mmol of benzoic acid (BA)". The other steps and parameters are the same as in Example 1. An organic small molecule benzoic acid (BA) modified iron-nickel layered double hydroxide catalyst is obtained, denoted as NiFe-LDH(BA).
[0035] Example 4: This comparative example is for preparing an iron-nickel layered double hydroxide catalyst modified with organic small molecule terephthalic acid (TPA). The difference between this comparative example and Example 1 is that "0.5 mmol of TMA" in step two is replaced with "0.5 mmol of terephthalic acid (TPA)". The other steps and parameters are the same as in Example 1. An iron-nickel layered double hydroxide catalyst modified with organic small molecule terephthalic acid (TPA) is obtained, denoted as NiFe-LDH(TPA).
[0036] Comparative Example 1: This comparative example prepares a ruthenium oxide (RuO2) catalyst by dropping a mixed slurry onto nickel foam. The specific preparation method is as follows:
[0037] 1. Mix 20 mg RuO2, 540 μL deionized water and 400 μL anhydrous ethanol evenly, then add 60 μL Nafion and sonicate for 30 min to obtain a mixed slurry.
[0038] 2. Take 200 μl of the mixed slurry and drop it onto a 1 × 1.5 cm plate. 2 The clean nickel foam was placed on a baking lamp and dried at 90 °C for 6 h to obtain the RuO2 catalyst.
[0039] Figure 1 , 2 SEM images of NiFe-LDH, NiFe-LDH(BA), NiFe-LDH(TPA), and NiFe-LDH(TMA) prepared in Examples 2, 3, 4, and 1, respectively, at different scales, can be seen from the images. Micron-sized catalysts are distributed on the nickel foam substrate. In the SEM images at magnification, it can be observed that as the number of hydroxyl groups in the organic small molecules increases, the catalyst gradually begins to exhibit a flower-like morphology.
[0040] Figure 5 , 6 High-resolution TEM and SAED images of NiFe-LDH and NiFe-LDH(TMA) prepared in Examples 2 and 1, respectively, show that the catalysts have a polycrystalline structure and the introduction of TMA increases the interplanar spacing of the catalysts.
[0041] Figure 7 The X-ray diffraction patterns of NiFe-LDH, NiFe-LDH(BA), NiFe-LDH(TPA), and NiFe-LDH(TMA) prepared in Examples 2, 3, 4, and 1 were compared with known phase spectra to determine the phase composition of the materials, and from... Figure 7 The XRD peaks shift to the left due to the introduction of small organic molecules, indicating an increase in interplanar spacing.
[0042] Using the NiFe-LDH(TMA) prepared in Example 1, the NiFe-LDH prepared in Example 2, the NiFe-LDH(BA) prepared in Example 3, the NiFe-LDH(TPA) prepared in Example 4, and the RuO2 catalyst prepared in Comparative Example 1 as working electrodes, and with 1M KOH seawater as the electrolyte, hydrogen evolution polarization curves were obtained by linear sweep voltammetry (LSV). The 1M KOH seawater was prepared by adding 1 mol of KOH to a 1L volumetric flask and then diluting it with seawater. The specific testing method is as follows: a three-electrode testing system consisting of the working electrode, the counter electrode (platinum sheet electrode), and the reference electrode (Hg / HgO electrode) was connected to an electrochemical workstation, and a scan was performed between 0 and 2 V at a scan rate of 5 mV / s to obtain the oxygen evolution polarization curves of each catalyst in alkaline seawater. Figure 8 As shown in Table 1.
[0043] Table 1. Overpotentials of the catalysts prepared in each example.
[0044] Example number catalyst <![CDATA[10 mA cm -2 Overpotential below Example 1 NiFe-LDH(TMA) 207 mV Example 2 NiFe-LDH 233 mV Example 3 NiFe-LDH(BA) 231 mV Example 4 NiFe-LDH(TPA) 218 mV Comparative Example 1 <![CDATA[RuO2 catalyst]]> 302 mV
[0045] pass Figure 8 As shown in Table 1, under alkaline seawater conditions, the performance of the organic small molecule TMA-modified iron-nickel layered double hydroxide catalyst NiFe-LDH(TMA) prepared in Example 1 is superior to that of Comparative Example 1, exhibiting performance of 207 mV@10 mA cm⁻¹ in seawater. -2 The superior performance of NiFe-LDH(TMA) is evident. Compared with commercially available ruthenium oxide catalysts, NiFe-LDH(TMA) exhibits intrinsic activity exceeding that of commercial RuO2, and its performance at high current densities is far superior to that of commercial RuO2.
[0046] Figure 9 The high-resolution XPS spectra of Fe 2p of NiFe-LDH(TMA) and NiFe-LDH prepared in Examples 1 and 2 are shown in the figure. It can be seen from the figure that the iron peak of NiFe-LDH(TMA) has shifted and a unique CO-Fe peak exists. The change in iron binding energy indicates that electron transfer has occurred between the TMA and NiFe-LDH framework through CO-Fe bonds, which helps to improve the structural stability of electrocatalysis and optimize the electronic configuration.
[0047] Figure 10 The organic small molecule TMA-modified iron-nickel layered double hydroxide catalyst NiFe-LDH(TMA) prepared in Example 1 was tested in alkaline seawater (1M KOH seawater) at 500 mA cm⁻¹. -2 The graph shows the change in potential over time under a constant current. It can be seen from the graph that in alkaline seawater at 500 mA cm⁻¹... -2Under these conditions, it operated stably for over 500 hours with minimal performance degradation, while the NiFe-LDH catalyst showed significant deactivation after only 200 hours of operation. This is because the presence of the CO-Fe bonds formed by TMA stabilizes the metal ions in NiFe-LDH and, through the action of Cl... - It repels and thus protects the electrode.
[0048] The organic small molecule TMA-modified iron-nickel layered double hydroxide catalyst NiFe-LDH(TMA) prepared in Example 1 and the NiFe-LDH catalyst prepared in Example 2 were used as oxygen evolution side catalysts, respectively. A commercial NiMo catalyst was used as the hydrogen evolution side catalyst to assemble an electrolyzer. 1M KOH seawater was used as the electrolyte, and linear sweep voltammetry (LSV) was performed. The polarization curve of the electrolyzer at 80°C is shown in the figure. Figure 11 As shown, from Figure 11 It can be seen that in alkaline seawater, the organic small molecule TMA-modified iron-nickel layered double hydroxide catalyst NiFe-LDH(TMA) prepared in Example 1 has better industrial-grade performance than NiFe-LDH.
[0049] Using NiFe-LDH(TMA) prepared in Example 1 as the oxygen evolution side catalyst and commercial NiMo as the cathode catalyst, an electrolyzer was assembled. 6M KOH seawater was used as the electrolyte, which was prepared by adding 6 mol of KOH to a 1L volumetric flask and then diluting the volume with seawater. The electrolyzer operated in alkaline seawater at 500 mA cm⁻¹. -2 The curve of potential change over time under constant current is shown in the figure. Figure 12 As shown, from Figure 12 It can be seen that NiFe-LDH(TMA) operates stably for more than 2500 hours with negligible performance degradation.
[0050] This invention relates to a binary nickel-iron layered double hydroxide catalyst modified with organic small molecules. By incorporating specific organic small molecules into the NiFe-LDH interlayer structure, the active metal sites are effectively anchored, simultaneously achieving improved catalytic performance and enhanced structural stability. The core advantages of this catalyst are: firstly, while maintaining high catalytic activity, it can effectively repel chloride ions (Cl-) in the electrolyte. - First, it significantly improves corrosion resistance in seawater environments; second, the catalyst does not contain precious metals, resulting in low raw material costs and a simple preparation process; third, it exhibits long-term operational stability exceeding 2500 hours under harsh conditions. This invention solves the key problems of high catalyst cost, complex processes, and insufficient stability in existing seawater electrolysis hydrogen production technologies, providing a feasible technical solution for developing efficient, durable, and low-cost industrial-scale seawater electrolysis hydrogen production anode catalysts.
Claims
1. An organic small molecule modified iron-nickel layered double hydroxide catalyst characterized in that, The catalyst is based on nickel foam, on which NiFe layered double hydroxides are grown, and the interlayers of the NiFe layered double hydroxides contain small organic molecules; among which the small organic molecules are cyclohexanecarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3,5-cyclohexanetriic acid, benzoic acid, terephthalic acid or pyromellitic acid.
2. The method for preparing the organic small molecule modified iron-nickel layered double hydroxide catalyst according to claim 1, characterized in that, This method is performed in the following steps:
1. The nickel foam is subjected to ultrasonic treatment in an organic solvent, dilute acid and anhydrous ethanol in sequence, and then cleaned with anhydrous ethanol and deionized water to obtain clean nickel foam.
2. A precursor solution is prepared using Fe(NO3)3·9H2O, Ni(NO3)2·6H2O, and small organic molecules. Clean nickel foam is then placed in the precursor solution for electrodeposition. The applied voltage during electrodeposition is -0.5 to -2 V, and the electrodeposition time is 10 to 40 min. After the electrodeposition reaction is completed, the nickel foam is removed and cleaned to obtain nickel foam with organic small molecules embedded in the interlayer of NiFe layered double hydroxide. The organic small molecules are cyclohexanecarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3,5-cyclohexanetriic acid, benzoic acid, terephthalic acid, or pyromellitic acid.
3. The foamed nickel with organic small molecules embedded in the interlayer of NiFe layered double hydroxide is dried to obtain an organic small molecule modified iron-nickel layered double hydroxide catalyst.
3. The method for preparing an organic small molecule modified iron-nickel layered double hydroxide catalyst according to claim 2, characterized in that, The organic solvent mentioned in step one is one or more of methanol, acetone, isoacetone, and ethylene glycol.
4. The method for preparing an organic small molecule modified iron-nickel layered double hydroxide catalyst according to claim 2 or 3, characterized in that, The dilute acid mentioned in step one is hydrochloric acid with a concentration of 5~14 mol / L.
5. The method for preparing an organic small molecule modified iron-nickel layered double hydroxide catalyst according to claim 2 or 3, characterized in that, In step two, the molar ratio of Fe(NO3)3·9H2O to Ni(NO3)2·6H2O in the precursor solution is 1:(0.2~5).
6. The method for preparing an organic small molecule modified iron-nickel layered double hydroxide catalyst according to claim 2 or 3, characterized in that, The molar concentration of small organic molecules in the precursor solution described in step two is 0.01~2 mmol / mL.
7. The application of the organic small molecule modified iron-nickel layered double hydroxide catalyst according to claim 1, characterized in that, This application involves using an organically modified iron-nickel layered double hydroxide catalyst in the electrolysis of seawater to produce hydrogen.