Preparation method and application of betaine-induced branch structure CoFe-based catalyst
By preparing a betaine-induced branched CoFe-based catalyst, the problems of insufficient activity and stability of CoFe-based catalysts in seawater systems were solved, achieving a lower oxygen evolution reaction overpotential and excellent chlorine corrosion resistance, making it suitable for seawater hydrogen production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH AT WEIHAI
- Filing Date
- 2026-03-26
- Publication Date
- 2026-05-26
AI Technical Summary
Existing CoFe-based catalysts suffer from insufficient activity and stability in seawater systems, especially in high-concentration Cl⁻ environments where they are prone to chlorine evolution side reactions and electrode corrosion. Commercial RuO₂ and IrO₂ catalysts are expensive and have limited selectivity.
A method for preparing CoFe-based catalysts with betaine-induced branched structures was adopted. By growing CoFe precursors in situ on a nickel foam substrate and introducing zwitterionic betaine, a branched structure was formed, which controlled the interfacial charge distribution and suppressed the chlorine evolution side reaction.
It exhibits a lower oxygen evolution reaction overpotential in alkaline seawater systems, improving reaction selectivity and chlorine corrosion resistance. It can operate stably for over 1000 hours with only 280mV overpotential at a current density of 500 mA cm⁻², showing promising prospects for engineering applications.
Smart Images
Figure CN122082020A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrocatalyst preparation and application, specifically relating to a method for preparing and applying a betaine-induced branched CoFe-based catalyst. Background Technology
[0002] Hydrogen energy, due to its high energy density and zero carbon emissions, is considered an important clean and renewable energy source connecting renewable energy with end-use energy. Seawater resources are abundant, and direct electrolysis of seawater to produce hydrogen has broad application prospects; however, seawater contains high concentrations of Cl... ⁻ It is easy to trigger chlorine evolution side reactions and electrode corrosion, which puts forward higher requirements for the selectivity and stability of the anodic OER catalyst.
[0003] Currently, commercial RuO2 and IrO2 catalysts suffer from insufficient selectivity, limited corrosion resistance, and high cost in seawater systems. While CoFe-based catalysts exhibit good OER activity, existing control strategies largely rely on high-temperature and high-pressure conditions, and their activity and stability still need improvement. Therefore, developing CoFe-based seawater OER catalysts with controllable structure, strong resistance to chlorine corrosion, and excellent stability is of great significance. Summary of the Invention
[0004] The present invention aims to solve the technical problems of poor activity and stability of existing CoFe-based catalysts, and provides a method for preparing and applying a betaine-induced branched CoFe-based catalyst.
[0005] The preparation method of the betaine-induced branched CoFe-based catalyst of the present invention is carried out according to the following steps:
[0006] 1. Cut the nickel foam (NF) into appropriate sizes, and ultrasonically clean it in acetone, hydrochloric acid, ethanol and water in sequence to remove surface oil and oxide layer, and then dry it to obtain clean nickel foam.
[0007] 2. Dissolve cobalt salt in isopropanol to obtain solution A; then dissolve iron salt in water to obtain solution B; add solution B dropwise to solution A with stirring, then immerse clean nickel foam in the solution, heat in a water bath for 5-6 h, then add zwitterions and continue the reaction for 18-20 h, then wash and dry to obtain a betaine-induced branched CoFe-based catalyst, denoted as CoFe-SG-B; the zwitterions are betaine, propionic betaine, or butyric betaine.
[0008] Furthermore, the cobalt salt mentioned in step two is cobalt chloride, cobalt nitrate, or cobalt sulfate.
[0009] Furthermore, the iron salt mentioned in step two is ferrous chloride, ferrous sulfate, or ferrous acetylacetone.
[0010] Furthermore, the molar ratio of cobalt salt to iron salt in step two is (2~4):1.
[0011] Furthermore, the molar ratio of cobalt salt and zwitterion mentioned in step two is (10~60):1.
[0012] Furthermore, the concentration of cobalt salt in solution A described in step two is 0.2~1 mol / L.
[0013] Furthermore, the water bath heating temperature described in step two is 20~70 ℃.
[0014] Furthermore, the drying temperature described in steps one and two is 30~60 ℃, and the drying time is 12~48h.
[0015] Furthermore, the stirring speed described in step two is 200~800 rpm.
[0016] The aforementioned application of the betaine-induced branched CoFe-based catalyst involves using it in the anodic oxygen evolution reaction of seawater hydrogen production.
[0017] This invention uses NF as the conductive framework and employs an in-situ growth strategy to construct a CoFe precursor structure. Interface modulation is achieved by introducing zwitterions into an isopropanol-water heterogeneous solution, inducing the formation of a branched structure to obtain a betaine-induced branched CoFe-based catalyst. Compared with CoFe-based catalysts prepared by traditional hydrothermal methods, the catalyst prepared in this invention exhibits significantly improved activity and structural stability. The preparation process is as follows: Figure 1 As shown.
[0018] The present invention has the following advantages over the prior art:
[0019] (1) In this invention, NF is grown in situ by directly immersing it in an isopropanol-water heterogeneous solution containing metal salts, and a catalytically active layer is constructed under mild conditions. Subsequently, zwitterionic betaine is introduced to induce the formation of a branched structure. This method avoids high-temperature and high-pressure hydrothermal conditions, has low energy consumption, simple process, and has the potential for large-scale preparation.
[0020] (2) This invention achieves synergistic optimization of structure regulation and interface function by inducing branched structures through betaine. Specifically, the acidic groups of betaine are anchored to the surface of the CoFe matrix, enhancing structural stability; the basic groups, under the influence of an electric field, are oriented towards the electrolyte interface, which can regulate the interfacial charge distribution and influence Cl... - It generates selective adsorption and common ion repulsion effects, thereby suppressing the chlorine evolution side reaction and improving the selectivity of OER and the stability of active sites.
[0021] (3) The CoFe-SG-B catalyst of the present invention exhibits a lower oxygen evolution reaction overpotential, higher reaction selectivity, and excellent resistance to chlorine corrosion in alkaline seawater systems. At an industrial-grade current density of 500 mA cm⁻¹... -2 It requires only 280mV overpotential and can operate stably for more than 1000 hours, showing good prospects for engineering applications. Attached Figure Description
[0022] Figure 1 This is a flowchart of the catalyst preparation process according to the present invention;
[0023] Figure 2 Here is a SEM image of the CoFe-SG-B catalyst prepared in Example 1;
[0024] Figure 3 This is the XRD pattern of the CoFe-SG-B catalyst prepared in Example 1;
[0025] Figure 4 This is a TEM image of the CoFe-SG-B catalyst prepared in Example 1;
[0026] Figure 5 This is an EDS surface scan image of the CoFe-SG-B catalyst prepared in Example 1;
[0027] Figure 6 This is a SEM image of the CoFe-LDH catalyst prepared in Comparative Example 2;
[0028] Figure 7 The XRD pattern of the CoFe-LDH catalyst prepared in Comparative Example 2 is shown below.
[0029] Figure 8 The linear sweep voltammetry curve of the CoFe-SG-B catalyst prepared in Example 1 is shown.
[0030] Figure 9 The linear sweep voltammetry curves of the CoFe-SG catalyst prepared in Comparative Example 1 are shown.
[0031] Figure 10 The linear sweep voltammetry curves of the CoFe-LDH catalyst prepared in Comparative Example 2 are shown.
[0032] Figure 11 These are linear sweep voltammetry curves of the CoFe-SG-B catalyst prepared in Example 1 before and after aging;
[0033] Figure 12 This is a comparison chart of the long-cycle performance of the CoFe-SG-B catalyst prepared in Example 1, the CoFe-SG catalyst prepared in Comparative Example 1, and the CoFe-LDH catalyst prepared in Comparative Example 2. Detailed Implementation
[0034] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0035] Example 1: The preparation method of the betaine-induced branched CoFe-based catalyst in this example is carried out according to the following steps:
[0036] 1. Cleaning of NF: Cut NF into 4 cm × 5 cm sizes and ultrasonically clean it in acetone, hydrochloric acid, ethanol and deionized water for 20 min each to remove surface oil and oxide layer. Then, vacuum dry it at 40 ℃ for 12 h to obtain clean nickel foam.
[0037] II. Preparation of CoFe-SG-B: 4.278 g of cobalt nitrate was dissolved in 72 mL of isopropanol to obtain solution A; 1.322 g of ferrous sulfate was dissolved in 24 mL of deionized water to obtain solution B; under stirring at 500 rpm, solution B was added dropwise to solution A and mixed thoroughly. Then, clean nickel foam was immersed in the mixed solution and reacted in a water bath at 40 ℃ for 6 h; then 0.06 g of betaine was added and the reaction was continued for 18 h; after the reaction was completed, the sample was taken out, washed with deionized water, and vacuum dried at 40 ℃ for 24 h to obtain the betaine-induced branched CoFe-based catalyst, denoted as CoFe-SG-B catalyst.
[0038] Comparative Example 1: This comparative example provides a method for preparing the CoFe-SG catalyst, and the specific steps are as follows:
[0039] 1. Cleaning of NF: Cut NF into 4 cm × 5 cm sizes and ultrasonically clean it for 20 min each in acetone, hydrochloric acid, ethanol and deionized water to remove surface oil and oxide layer. Then, vacuum dry it at 40 ℃ for 12 h to obtain clean nickel foam.
[0040] II. Preparation of CoFe-SG: 4.278 g of cobalt nitrate was weighed and dissolved uniformly in 72 ml of isopropanol to obtain solution A; 1.322 g of ferrous sulfate was weighed and dissolved in 24 ml of water to obtain solution B; solution B was added dropwise to solution A under stirring at 500 rpm, and then clean nickel foam was immersed in the solution. The reaction was heated in a water bath at 40 ℃ for 24 h, then washed and dried under vacuum at 40 ℃ for 24 h to obtain the comparative catalyst, denoted as CoFe-SG catalyst.
[0041] Comparative Example 2: This comparative example provides a method for preparing the CoFe-LDH catalyst. The specific steps are as follows:
[0042] 1. Cleaning of NF: Cut NF into 2 cm × 3 cm sizes and ultrasonically clean it for 20 min each in acetone, hydrochloric acid, ethanol and deionized water to remove surface oil and oxide layer. Then, vacuum dry it at 40 ℃ for 12 h to obtain clean nickel foam.
[0043] II. Preparation of CoFe-LDH: Weigh 0.873 g cobalt nitrate, 0.404 g ferric nitrate and 0.3 g urea and dissolve them evenly in 30 ml of water. Add NF to the solution and react at 120 °C for 10 h. After washing, dry under vacuum at 40 °C for 12 h to obtain the comparative catalyst, which is denoted as CoFe-LDH catalyst.
[0044] Schematic diagrams and scanning electron microscope images of the CoFe-SG-B catalyst prepared in Example 1 are shown below. Figure 1 and Figure 2 As shown, from Figure 2 It can be seen that the catalyst exhibits a distinct branched nanoflower structure with a uniform morphology.
[0045] The XRD patterns of the CoFe-SG-B catalyst prepared in Example 1 and the CoFe-SG catalyst prepared in Comparative Example 1 are shown below. Figure 3 As shown, the characteristic diffraction peaks of the nickel foam substrate only appear at 44.5°, 51.8° and 76.4° in the spectrum, and no other obvious crystal phase diffraction peaks are observed. Figure 4 The image shows a TEM image of the CoFe-SG-B catalyst prepared in Example 1. The XRD results combined with the analysis show that the catalysts obtained in Example 1 and Comparative Example 1 are mainly amorphous.
[0046] Figure 5 These are EDS surface scan images of the CoFe-SG-B catalyst prepared in Example 1; from Figure 5 It can be seen that the elements Co, Fe, N, and O are evenly distributed.
[0047] SEM image of the CoFe-LDH catalyst prepared in Comparative Example 2 is shown below. Figure 6 As shown, from Figure 6 As can be seen, the CoFe-LDH catalyst exhibits a typical nanosheet morphology; its XRD pattern is shown below. Figure 7 As shown, the diffraction peak positions are consistent with those on the standard card, indicating that the sample has a crystalline CoFe-LDH structure, verifying the reproducibility and structural consistency of the traditional hydrothermal synthesis method.
[0048] The CoFe-SG-B catalyst prepared in Example 1, the CoFe-SG catalyst prepared in Comparative Example 1, and the CoFe-LDH catalyst prepared in Comparative Example 2 were used as working electrodes, with carbon rods as counter electrodes, Hg / HgO as reference electrodes, and alkaline seawater as electrolyte. The catalysts were first activated to stability at 1.2–1.6 V, and then linear sweep voltammetry was performed at 0–2.5 V. The linear sweep voltammetry curves are shown below. Figure 8 , Figure 9 and Figure 10 As shown, from Figure 8 , Figure 9 and Figure 10 It can be seen that, under the same current density, the CoFe-SG-B catalyst prepared in Example 1 requires the lowest overpotential, at 500 mA cm⁻¹. -2 At the specified current density, only a 280 mV overpotential is required, indicating that the branched structure induced by betaine significantly enhances the catalyst's activity and reaction selectivity. Alkaline seawater was prepared by adding 56.11 g of KOH to 1 L of untreated seawater, followed by filtration and precipitation; the supernatant was the alkaline seawater.
[0049] The CoFe-SG-B catalyst prepared in Example 1 was subjected to an aging test in alkaline seawater electrolyte. The linear sweep voltammetry curves before and after aging are shown below. Figure 11 As shown, from Figure 11 It can be seen that after 5000 cycles of aging in alkaline seawater electrolyte, the overpotential of the CoFe-SG-B catalyst showed almost no significant change, demonstrating good cycle stability.
[0050] Long-cycle diagrams of the CoFe-SG-B catalyst prepared in Example 1, the CoFe-SG catalyst prepared in Comparative Example 1, and the CoFe-LDH catalyst prepared in Comparative Example 2 are shown below. Figure 12 As shown, from Figure 12 It can be seen that the CoFe-LDH catalyst prepared in Comparative Example 2 showed a significant voltage increase after about 200 h; the CoFe-SG catalyst prepared in Comparative Example 1 showed a voltage fluctuation increase after about 700 h; while the CoFe-SG-B catalyst prepared in Example 1 maintained a relatively stable voltage within 1000 h, without significant decay and with the lowest overpotential, showing excellent long-term stability and practical application potential.
[0051] This invention is based on a zwitterionic betaine-regulated structure construction strategy, which first immerses pretreated nickel foam in a Co-containing solution. 2+ and Fe 2+In situ growth was achieved in an isopropanol-water heterogeneous solution, followed by the introduction of betaine to induce branching structures. The acidic groups of the betaine anchored to the surface of the CoFe matrix, enhancing structural stability. Under the influence of an electric field, the basic groups oriented towards the electrolyte interface, regulating the interfacial charge distribution and selectively adsorbing some Cl₂. - At the same time, it repels another part of Cl at the interface. - This suppresses the chlorine evolution side reaction, significantly improving the activity and stability of the catalyst, which can be used for hydrogen production from seawater.
Claims
1. A method for preparing a betaine-induced branched CoFe-based catalyst, characterized in that, This method is performed in the following steps:
1. Cut the nickel foam into appropriate sizes and ultrasonically clean it in acetone, hydrochloric acid, ethanol and water in sequence to remove surface oil and oxide layer. Then dry it to obtain clean nickel foam.
2. Dissolve the cobalt salt in isopropanol to obtain solution A; The iron salt is then dissolved in water to obtain solution B; Solution B was added dropwise to solution A with stirring, and then clean nickel foam was immersed in the solution. The reaction was heated in a water bath for 5-6 h. After adding zwitterions, the reaction was continued for 18-20 h. The solution was then washed and dried to obtain a betaine-induced branched CoFe-based catalyst, denoted as CoFe-SG-B. The zwitterions were betaine, propionic betaine, or butyric betaine.
2. The method for preparing a betaine-induced branched CoFe-based catalyst according to claim 1, characterized in that, The cobalt salt mentioned in step two is cobalt chloride, cobalt nitrate, or cobalt sulfate.
3. The method for preparing a betaine-induced branched CoFe-based catalyst according to claim 1 or 2, characterized in that, The iron salt mentioned in step two is ferrous chloride, ferrous sulfate, or ferrous acetylacetone.
4. The method for preparing a betaine-induced branched CoFe-based catalyst according to claim 1 or 2, characterized in that, The molar ratio of cobalt salt to iron salt mentioned in step two is (2~4):
1.
5. The method for preparing a betaine-induced branched CoFe-based catalyst according to claim 1 or 2, characterized in that, The molar ratio of cobalt salt and zwitterion mentioned in step two is (10~60):
1.
6. The method for preparing a betaine-induced branched CoFe-based catalyst according to claim 1 or 2, characterized in that, The concentration of cobalt salt in solution A mentioned in step two is 0.2~1 mol / L.
7. The method for preparing a betaine-induced branched CoFe-based catalyst according to claim 1 or 2, characterized in that, The water bath heating temperature mentioned in step two is 20~70 ℃.
8. A method for preparing a betaine-induced branched CoFe-based catalyst according to claim 1 or 2, characterized in that, The drying temperature in steps one and two is 30~60 ℃, and the drying time is 12~48 h.
9. A method for preparing a betaine-induced branched CoFe-based catalyst according to claim 1 or 2, characterized in that, The stirring speed mentioned in step two is 200~800 rpm.
10. The application of the betaine-induced branched CoFe-based catalyst prepared by the method of claim 1, characterized in that, This application involves using a betaine-induced branched CoFe-based catalyst for the anodic oxygen evolution reaction in seawater hydrogen production.