Bimetallic organogel electrode material adapted to wide power fluctuations, and preparation method and application thereof

Abstract

The application discloses a bimetallic organic gel electrode material suitable for wide power fluctuation and a preparation method and application thereof. The preparation method of the bimetallic organic gel electrode material comprises the following steps: dissolving transition metal nickel salt and transition metal cobalt salt in ethanol to obtain a transition metal salt mixed solution; under the atmosphere of nitrogen or inert gas, the transition metal salt mixed solution is added dropwise into a terephthalic acid mixed solution at 70-90 DEG C, and solvent thermal reaction is continuously carried out at 70-90 DEG C to obtain a colloidal suspension; centrifugation is carried out to obtain a precipitate; washing and vacuum drying are carried out to obtain the bimetallic organic gel electrode material. The bimetallic organic gel electrode material has excellent electrocatalytic hydrogen evolution and oxygen evolution activity, has a lower overpotential in the HER process in an alkaline environment, the lowest overpotential is 28 mV, and still has good stability under different large current densities, and has good electrochemical activity and wide power stability.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical catalytic hydrogen production technology, specifically relating to a bimetallic organic gel electrode material adapted to wide power fluctuations, its preparation method, and its application. Background Technology

[0002] With my country's comprehensive green transformation in economic and social development, renewable energy sources such as solar, wind, and tidal power have experienced tremendous growth. However, during use, the volatility and intermittency of renewable energy supply prevent it from providing a continuous and stable energy supply. In this context, renewable energy is being combined with energy storage systems to address issues such as power fluctuations in intermittent power generation and the curtailment of wind and solar power due to insufficient grid absorption capacity. Currently, photovoltaic and wind power generation primarily rely on highly efficient batteries for energy storage; however, batteries have limitations such as low energy density and short storage time, hindering their further application and development. In contrast, hydrogen energy storage offers advantages such as high energy density and long storage time, thus becoming a highly efficient method for regulating, storing, and converting energy.

[0003] Hydrogen energy is a high-energy-density, clean, environmentally friendly, and renewable energy carrier. Electrolysis of water using renewable energy sources to produce hydrogen achieves zero carbon emissions at the source and generates high-purity hydrogen. This is a key technology for efficiently utilizing renewable energy, accelerating hydrogen energy development, and achieving the "dual-carbon" goal. Currently, the slow reaction kinetics in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are a major problem facing the development of water electrolysis, leading to high overpotentials. Therefore, reducing energy consumption and lowering hydrogen production costs are crucial for the sustainable and large-scale development of the hydrogen energy industry. Simultaneously, developing water electrolysis systems suitable for wide power fluctuations can effectively alleviate the curtailment of wind and solar power in wind-solar hybrid power generation systems, effectively improving energy utilization efficiency. Since both HER and OER consist of multi-step reactions, including the adsorption and desorption of reactant molecules, electron transfer, and the formation and diffusion of generated gases, this places demands on the intrinsic activity of catalysts. While traditional noble metal electrocatalysts possess good catalytic activity, their limited reserves and high costs severely restrict their large-scale application. To overcome these problems, it is crucial to develop efficient, stable, and low-cost electrocatalysts.

[0004] Organometallic gels (MOGs) are an emerging electrochemical material, a coordination-driven supramolecular polymer. Their unique characteristic lies in the self-assembly of metal ions and ligands to form gel factors. These gel factors, in fibrous, sheet-like, or granular forms, further develop into an interwoven three-dimensional network structure through intermolecular forces such as hydrogen bonds, π-π stacking, and van der Waals forces. However, MOGs generally exhibit low electronic conductivity. Currently reported MOGs mostly focus on the coordination of a single metal ion with a ligand, significantly limiting the controllability of their coordination with the central metal atom and their structural integrity. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a bimetallic organogel electrode material that is adaptable to wide power fluctuations. This bimetallic organogel electrode material not only increases the exposure ratio of metal active sites, but also improves the conductivity and electrocatalytic performance of the bimetallic organogel electrode material, and maintains high stability under high current density fluctuations (i.e., wide power fluctuations).

[0006] Another objective of this invention is to provide a method for preparing a bimetallic organic gel electrode material. This method involves controlling the molar ratio of two metals, and obtaining the bimetallic organic gel electrode material through a hot injection reaction of a salt solution of transition metals cobalt and nickel and terephthalic acid.

[0007] Another object of the present invention is to provide a bimetallic organic gel electrode material adapted to wide power fluctuations for use in hydrogen evolution or oxygen evolution.

[0008] The objective of this invention is achieved through the following technical solutions.

[0009] A method for preparing a bimetallic organogel electrode material includes the following steps:

[0010] Transition metal nickel salt and transition metal cobalt salt are dissolved in ethanol to obtain a transition metal salt mixture. Under a nitrogen or inert gas atmosphere, the transition metal salt mixture is added dropwise to a terephthalic acid mixture at 70-90℃ (using the hot injection method), and the reaction is continued at 70-90℃ for 3-5 hours to obtain a colloidal suspension. The suspension is centrifuged to obtain a precipitate, which is washed and vacuum dried to obtain a bimetallic organic gel electrode material. The ratio of nickel in the transition metal nickel salt, cobalt in the transition metal cobalt salt, and terephthalic acid in the terephthalic acid mixture is x:y:(x+y), where x = 1-2 and y = 1-2.

[0011] In the above technical solution, the transition metal cobalt salt is cobalt nitrate hexahydrate or cobalt chloride, and the transition metal nickel salt is nickel nitrate hexahydrate or nickel chloride.

[0012] In the above technical solution, the ratio of the molar amount of nickel to the volume fraction of ethanol in the transition metal nickel salt is (1-2):(20-60), where the molar amount is in mmol and the volume fraction is in mL.

[0013] In the above technical solution, the terephthalic acid mixture is a mixture of terephthalic acid and dimethyl sulfoxide, and the concentration of terephthalic acid in the terephthalic acid mixture is 0.5-1 mM.

[0014] In the above technical solution, transition metal nickel salt and transition metal cobalt salt are dissolved in ethanol by ultrasound for 30 to 60 minutes.

[0015] In the above technical solution, the terephthalic acid mixture is first stirred at 70-90°C for at least 30 minutes, and then the transition metal salt mixture is added dropwise to the terephthalic acid mixture at 70-90°C using a hot injection method. The terephthalic acid mixture is kept stirred while the transition metal salt mixture is added dropwise to the terephthalic acid mixture.

[0016] In the above technical solution, the nitrogen or inert gas atmosphere is achieved by replacing nitrogen or inert gas at least three times. The operation of replacing nitrogen or inert gas includes: evacuating to -0.1 to -0.01 MPa and introducing nitrogen or inert gas.

[0017] In the above technical solution, the washing operation includes: centrifuging the precipitate 3 to 5 times each with ethanol and dimethyl sulfoxide in sequence.

[0018] In the above technical solution, the vacuum drying temperature is 60-90℃, and the vacuum drying time is 12-24h.

[0019] The bimetallic organogel electrode material obtained by the above preparation method.

[0020] The above-mentioned bimetallic organic gel electrode materials are used in hydrogen evolution or oxygen evolution.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The bimetallic organic gel electrode material of the present invention has excellent proton conductivity and electronic conductivity, which is beneficial to the reaction of H ions and other reaction intermediates and the transport of electrons, and is beneficial to the electrocatalytic hydrogen evolution. The bimetallic organic gel electrode material of the present invention has excellent electrocatalytic hydrogen evolution and oxygen evolution activities.

[0023] (2) The bimetallic organic gel electrode material of the present invention has a low overpotential in the HER process in an alkaline environment, with the lowest overpotential being 28mV, and maintains good stability under different high current densities, exhibiting good electrochemical activity and wide power stability.

[0024] (3) The preparation method of the present invention synthesizes bimetallic mechanical gel electrode material by hot injection. Due to the difference in atomic radius of bimetals, the bimetallic mechanical gel electrode material contains more defects and a larger specific surface area, which promotes the transport process of reaction intermediates inside and effectively increases the HER reaction kinetics.

[0025] (4) The preparation method of the present invention is simple, low-cost, suitable for large-scale commercial production, and environmentally friendly. Attached Figure Description

[0026] Figure 1 The images are scanning electron microscope (SEM) images of the bimetallic organic gel electrode materials prepared in Examples 1 to 3, where (a) is Example 1, (b) is Example 2, and (c) is Example 3.

[0027] Figure 2 High-resolution transmission electron microscopy (HRTEM) images of the bimetallic organic gel electrode materials prepared in Examples 1-3, where (a) is Example 1, (b) is Example 2, and (c) is Example 3;

[0028] Figure 3 The images show the XRD patterns of the bimetallic organogel electrode materials prepared in Examples 1-3 and the metal-organic gel materials prepared in Comparative Examples 1-2.

[0029] Figure 4 Fourier transform infrared (FTIR) spectra of the bimetallic organic gel electrode materials prepared in Examples 1-3;

[0030] Figure 5 Raman spectra of the bimetallic organic gel electrode materials prepared in Examples 1-3;

[0031] Figure 6 The elemental distribution mapping characterization diagram is shown for the bimetallic organic gel electrode material prepared in Example 1.

[0032] Figure 7 The hydrogen evolution reaction-polarization curves (HER-LSV) of the bimetallic organogel electrode materials prepared in Examples 1-3 are shown.

[0033] Figure 8 Hydrogen evolution reaction-polarization curves (HER-LSV) of the organometallic gel materials prepared in Comparative Examples 1-2, the organometallic compound materials prepared in Comparative Examples 3-4, and the bimetallic organometallic compound materials prepared in Comparative Example 5.

[0034] Figure 9Tafel curves of the hydrogen evolution reaction of the bimetallic organic gel electrode materials prepared in Examples 1-3;

[0035] Figure 10 Tafel curves of the hydrogen evolution reaction of the organometallic gel materials prepared in Comparative Examples 1-2 and the organometallic compound materials prepared in Comparative Examples 3-4;

[0036] Figure 11 Tafel curves of the hydrogen evolution reaction of the bimetallic organometallic compound material prepared in Comparative Example 5;

[0037] Figure 12 The bimetallic organogel electrode material prepared in Example 1 was tested at 10 mA cm⁻¹. -2 The hydrogen evolution reaction voltage test diagram after maintaining the current density for 175 hours;

[0038] Figure 13 The organometallic gel materials prepared in Comparative Examples 1-2 and the organometallic compound materials prepared in Comparative Examples 3-4 were subjected to a 10 mA cm⁻¹ test. -2 Graph of hydrogen evolution reaction voltage measured under current density for 10 hours;

[0039] Figure 14 The bimetallic organometallic compound material prepared for Comparative Example 5 was tested at 10 mA cm⁻¹. -2 Graph of hydrogen evolution reaction voltage measured under current density for 10 hours;

[0040] Figure 15 The bimetallic organogel electrode material prepared in Example 1 was tested at 100, 200, and 400 mA cm⁻¹. -2 Test graph of hydrogen evolution reaction voltage maintained for 65 hours under fluctuating current density;

[0041] Figure 16 The oxygen evolution reaction-polarization curves (OER-LSV) of the bimetallic organogel electrode materials prepared in Examples 1-3 are shown.

[0042] Figure 17 EIS impedance test diagrams of the bimetallic organogel electrode materials prepared in Examples 1-3 and the metal-organic gel materials prepared in Comparative Examples 1-2. Detailed Implementation

[0043] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0044] In the examples below, the Nafion solution (5 wt%) was purchased from Ron Reagents, Inc., and the concentration of perfluorosulfonic acid polymer (Nafion) in the Nafion solution (5 wt%) was 5 wt%.

[0045] In the following examples, a Bio-Logic SP-150e (dual-channel) electrochemical workstation from France was used for linear sweep voltammetry (LSV) testing and hydrogen evolution stability testing.

[0046] In the following embodiments, a nitrogen atmosphere is achieved by purging nitrogen three times. The nitrogen purging operation includes: evacuating to -0.1 MPa and introducing nitrogen.

[0047] Examples 1-3

[0048] A method for preparing a bimetallic organogel electrode material includes the following steps:

[0049] Transition metal nickel salt, transition metal cobalt salt, and ethanol were mixed and sonicated for 30 min. This mixture was used to dissolve the transition metal nickel salt and transition metal cobalt salt in ethanol, yielding a brown, transparent transition metal salt mixture. A colorless, transparent terephthalic acid mixture was placed in a round-bottom flask under a nitrogen atmosphere and stirred at 70°C for 30 min. Then, under stirring, the transition metal salt mixture was slowly added dropwise to the terephthalic acid mixture at 70°C using a hot-pour method. The reaction was continued at 70°C for 3 hours under stirring to obtain a homogeneous colloidal suspension. The suspension was centrifuged to obtain a precipitate, which was then washed five times each with ethanol and dimethyl sulfoxide. After washing, the mixture was vacuum dried at 85℃ for 20 h to obtain a bimetallic organic gel electrode material. The transition metal cobalt salt was cobalt nitrate hexahydrate, and the transition metal nickel salt was nickel nitrate hexahydrate. The ratio of nickel (Ni) in the transition metal nickel salt, cobalt (Co) in the transition metal cobalt salt, and terephthalic acid in the terephthalic acid mixture, G, was given by weight. The ratio of the weight of nickel in the transition metal nickel salt to the volume of ethanol was given by volume. The weight of weight is expressed in mmol, and the volume is expressed in mL. The terephthalic acid mixture was a mixture of terephthalic acid and dimethyl sulfoxide, and the concentration of terephthalic acid in the terephthalic acid mixture was 1 mM.

[0050] The W, G and number of the bimetallic organic gel electrode materials prepared in Examples 1-3 are shown in Table 1.

[0051] Table 1

[0052]

[0053] Comparative Example 1

[0054] A method for preparing a metal-organic gel material (designated as Ni-MOG) includes the following steps:

[0055] A transition metal nickel salt was dissolved in ethanol by sonication for 30 minutes to obtain a green and transparent transition metal salt solution. A colorless and transparent terephthalic acid mixture was placed in a round-bottom flask under a nitrogen atmosphere and stirred at 70°C for 30 minutes. Then, while stirring, the transition metal salt solution was slowly added dropwise to the terephthalic acid mixture at 70°C using a hot-injection method. The reaction was continued at 70°C with stirring for 3 hours to obtain a homogeneous colloidal suspension. The suspension was centrifuged to obtain a precipitate, which was then washed five times each with ethanol and dimethyl sulfoxide. After washing, the mixture was vacuum dried at 85℃ for 20 h to obtain a metal-organic gel material. The ratio of nickel (Ni) in the transition metal nickel salt to terephthalic acid in the terephthalic acid mixture was 1:1. The transition metal nickel salt was nickel nitrate hexahydrate. The ratio of the molar amount of nickel to the volume amount of ethanol in the transition metal nickel salt was 1:20. The molar amount was expressed in mmol and the volume amount in mL. The terephthalic acid mixture was a mixture of terephthalic acid and dimethyl sulfoxide. The concentration of terephthalic acid in the terephthalic acid mixture was 1 mM.

[0056] Comparative Example 2

[0057] A method for preparing a metal-organic gel material (No.: Co-MOG) is basically the same as that of Comparative Example 1, except for the transition metal salt solution. The transition metal salt solution of this comparative example is prepared by dissolving a cobalt transition metal salt (cobalt nitrate hexahydrate) in ethanol by sonication for 30 min to obtain a pink transparent transition metal salt solution. The ratio of cobalt (Co) in the transition metal cobalt salt to terephthalic acid in the terephthalic acid mixture is 1:1, and the ratio of the molar amount of cobalt in the transition metal cobalt salt to the volume amount of ethanol is 1:20. The unit of molar amount is mmol, and the unit of volume amount is mL.

[0058] Comparative Example 3

[0059] A method for preparing an organometallic compound material (designated: Ni-MOC) includes the following steps:

[0060] The transition metal nickel salt was dissolved in ethanol by sonication for 30 min to obtain a green and transparent transition metal salt solution. A colorless and transparent terephthalic acid mixture was placed in a round-bottom flask under a nitrogen atmosphere and stirred at room temperature for 30 min. Then, while stirring, the transition metal salt solution was slowly added dropwise to the terephthalic acid mixture at 20–25 °C, and the reaction was continued at room temperature for 3 hours to obtain a suspension. Centrifugation yielded a small amount of precipitate, which was washed five times each with ethanol and dimethyl sulfoxide, and then incubated under vacuum at 85 °C. After drying for 20 hours, a metal-organic compound material was obtained. The ratio of nickel (Ni) in the transition metal nickel salt to terephthalic acid in the terephthalic acid mixture was 1:1. The transition metal nickel salt was nickel nitrate hexahydrate. The ratio of the molar amount of nickel to the volume amount of ethanol in the transition metal nickel salt was 1:20. The molar amount was expressed in mmol and the volume amount in mL. The terephthalic acid mixture was a mixture of terephthalic acid and dimethyl sulfoxide. The concentration of terephthalic acid in the terephthalic acid mixture was 1 mM.

[0061] Comparative Example 4

[0062] A method for preparing an organometallic compound material (No.: Co-MOC) is basically the same as that of Comparative Example 3, except for the transition metal salt solution. The transition metal salt solution of this comparative example is prepared by dissolving a cobalt transition metal salt (cobalt nitrate hexahydrate) in ethanol by sonication for 30 min to obtain a pink transparent transition metal salt solution. The ratio of cobalt (Co) in the transition metal cobalt salt to terephthalic acid in the terephthalic acid mixture is 1:1, and the ratio of the molar amount of cobalt in the transition metal cobalt salt to the volume fraction of ethanol is 1:20. The unit of molar amount is mmol, and the unit of volume fraction is mL.

[0063] Comparative Example 5

[0064] A method for preparing a bimetallic organometallic compound material (designated: NiCo-MOC) includes the following steps:

[0065] Transition metal nickel salt, transition metal cobalt salt, and ethanol were mixed and sonicated for 30 min to dissolve the transition metal nickel salt and transition metal cobalt salt in ethanol, yielding a brown, transparent transition metal salt mixture. A colorless, transparent terephthalic acid mixture was placed in a round-bottom flask under a nitrogen atmosphere and stirred at room temperature for 30 min. While stirring, the transition metal salt mixture was slowly added dropwise to the terephthalic acid mixture, and stirring continued at room temperature for 15 min. Subsequently, a solvothermal reaction was carried out at 70°C for 3 hours with stirring to obtain a suspension. Centrifugation yielded a small amount of precipitate, which was washed five times each with ethanol and dimethyl sulfoxide, respectively. The bimetallic organometallic compound material was obtained by vacuum drying at 85℃ for 20 h. The ratio of nickel (Ni) in the transition metal nickel salt, cobalt (Co) in the transition metal cobalt salt, and terephthalic acid in the terephthalic acid mixture was 1:1:2. The transition metal nickel salt was nickel nitrate hexahydrate, and the transition metal cobalt salt was cobalt nitrate hexahydrate. The ratio of the molar amount of nickel to the volume amount of ethanol in the transition metal nickel salt was 1:40. The molar amount was expressed in mmol, and the volume amount was expressed in mL. The terephthalic acid mixture was a mixture of terephthalic acid and dimethyl sulfoxide, and the concentration of terephthalic acid in the terephthalic acid mixture was 1 mM.

[0066] Figure 1 The images shown are SEM images of the bimetallic organogel electrode materials prepared in Examples 1-3. Figure 1 (a) is Example 1. Figure 1 (b) is Example 2. Figure 1 (c) is Example 3. From Figure 1 It can be seen that the bimetallic organic gel electrode materials prepared in Examples 1 to 3 are all rod-shaped, with smooth surfaces and similar diameters. However, the particle size of the bimetallic organic gel electrode material prepared in Example 1 is significantly larger than that of the bimetallic organic gel electrode materials prepared in Examples 2 to 3.

[0067] Figure 2 The images shown are HRTEM images of the bimetallic organogel electrode materials prepared in Examples 1-3. Figure 2 (a) is Example 1. Figure 2 (b) is Example 2. Figure 2 (c) is Example 3. From Figure 2 It can be seen that the surface of the bimetallic organic gel electrode materials prepared in Examples 1 to 3 all exhibit ribbon-like curved stripes. This is because Ni and Co coordinate with the O atoms on the carboxyl groups of terephthalic acid to form an aromatic layer. After coordination, slightly distorted octahedral units are formed, exhibiting stronger electronic interactions, leading to lattice distortion and forming a structure with long-range order and short-range disorder. This will expose more active sites and increase the number of unsaturated metal sites.

[0068] Figure 3 The images show the XRD patterns of the bimetallic organogel electrode materials prepared in Examples 1-3 and the metal-organogel materials prepared in Comparative Examples 1-2. Figure 3 It can be seen that the bimetallic organogel electrode materials prepared in Examples 1-3 and the metal organogel materials prepared in Comparative Examples 1-2 have similar crystal structures and basically the same diffraction angles. Among them, the metal organogel materials prepared in Comparative Examples 1-2 are single-metal coordination materials, with lower diffraction intensity and poorer crystallinity.

[0069] Figure 4 The images show the FTIR spectra of the bimetallic organogel electrode materials prepared in Examples 1-3. Figure 4 It can be seen that the bimetallic organogel electrode material prepared in Example 1 has a performance of 3002 cm⁻¹. -1 The vibrational peak at 1687 cm⁻¹ is attributed to the CH bond in the ligand (terephthalic acid). -1 The vibrational peak at 1325 cm⁻¹ is attributed to the C=O bond in the ligand. -1 The vibrational peak at 915 cm⁻¹ is attributed to the OH bond in the ligand and the peak at 915 cm⁻¹. -1 The vibrational peak at 456 cm⁻¹ is attributed to the corresponding C / C bond in the ligand. -1 The corresponding absorption peaks are the bonding absorption peaks of metal (Ni and Co) and oxygen (O), which proves that the metal coordinates with the carboxylic acid site of terephthalic acid to form a metal-organic gel.

[0070] Figure 5 Raman spectroscopy images of the bimetallic organometallic gel electrode materials prepared in Examples 1-3 are shown. Figure 5 It can be seen that at 2920cm -1 and 1047cm -1 The positions correspond to the CH bond and aromatic ring in the ligand, respectively.

[0071] Figure 6 This is the elemental distribution mapping characterization diagram of the bimetallic organic gel electrode material prepared in Example 1, from... Figure 6 It can be seen that Co and Ni elements are uniformly distributed on the surface of the bimetallic organic gel electrode material prepared in Example 1, combined with... Figures 1-6 This indicates that the bimetallic organogel electrode material prepared in Example 1 was successfully synthesized.

[0072] Example 5

[0073] Three-electrode system: with 1 mol L -1Potassium hydroxide (KOH) solution (a mixture of KOH and water) was used as the electrolyte. Electrode active material was coated onto nickel foam to form the working electrode. (Coating method: 3 mg of electrode active material, 7 mg of carbon black, 965 μL of isopropanol, and 35 μL of Nafion solution (5 wt%) were mixed evenly, coated onto nickel foam, and dried to obtain the working electrode. The loading of electrode active material on the working electrode was 0.3 mg / cm³.) -2 Using Hg / HgO as the reference electrode and a platinum sheet as the counter electrode, linear sweep voltammetry (LSV) was performed at 5 mV / s. -1 LSV polarization curves were obtained at a scan rate of 10 ...

[0074] According to the literature (Stable hydrogen evolution reaction at high current densities via designing the Ni single atoms and Ru nanoparticles linked by carbon bridges, Nature Communications, volume 15, article number: 2218(2024)), hydrogen evolution reaction occurs in the voltage range of -0.8 to 0.0 V (versus: RHE). The hydrogen evolution reaction-polarization curves (HER-LSV) of the bimetallic organic gel electrode materials prepared in Examples 1-3 as electrode active materials are shown below. Figure 7 As shown, the hydrogen evolution reaction-polarization curves (HER-LSV) of the metal-organic gel materials prepared in Comparative Examples 1-2, the metal-organic compound materials prepared in Comparative Examples 3-4, and the bimetallic organometallic compound materials prepared in Comparative Example 5, respectively, as electrode active materials, are as follows: Figure 8 As shown, when the current density reaches 10 mA cm⁻¹ -2 At the same time, the hydrogen evolution overpotential (corresponding to) of the bimetallic organogel electrode materials prepared in Examples 1-3, the metal-organic gel materials prepared in Comparative Examples 1-2, the metal-organic chemical materials prepared in Comparative Examples 3-4, and the bimetallic organochemical material prepared in Comparative Example 5 is compared with that of the bimetallic organochemical material prepared in Examples 5. Figure 7 and Figure 8 -10mA cm on the ordinate -2 The absolute values ​​of the x-axis are shown in Table 2.

[0075] Table 2

[0076] Examples / Comparative Examples Hydrogen evolution overpotential (unit: mV) Example 1 28mV Example 2 43mV Example 3 69mV Comparative Example 1 165mV Comparative Example 2 181mV Comparative Example 3 376mV Comparative Example 4 400mV Comparative Example 5 307mV

[0077] As shown in Table 2, the hydrogen evolution overpotentials of the bimetallic organogel electrode materials prepared in Examples 1-3 are all relatively low, with the bimetallic organogel electrode material prepared in Example 1 exhibiting the lowest hydrogen evolution overpotential. This may be due to the difference in atomic radii between the two metals, which causes tensile strain in the overall structure, resulting in more defects and a larger specific surface area, thereby increasing the reaction intermediates (such as H+). + The contact between ions and the working electrode surface and the promotion of electron transport within it effectively increase the HER reaction kinetics. The organometallic materials prepared in Comparative Examples 3-4 and the bimetallic organometallic materials prepared in Comparative Example 5 have extremely high hydrogen evolution overpotentials. This may be because the solvothermal reaction and the low temperature during dropwise addition result in poor crystallinity and disordered internal structure of the organometallic materials, with an indistinct gel-like appearance, thus leading to low conductivity and low yield.

[0078] The logarithmic value of the current obtained from the linear sweep voltammetry (LSV) test was used to obtain the Tafel curve for electrocatalytic hydrogen evolution, as shown in the figure. Figure 9 , Figure 10 and Figure 11 As shown in Table 3, the Tafel slopes are as follows. Table 3 shows that the organometallic gel materials prepared in Comparative Examples 1-2, the organometallic compound materials prepared in Comparative Examples 3-4, and the bimetallic organometallic compound material prepared in Comparative Example 5 exhibit larger Tafel slopes for electrocatalytic hydrogen evolution. The bimetallic organogel electrode materials prepared in Examples 1-3 all have relatively low Tafel slopes for electrocatalytic hydrogen evolution. Among them, the bimetallic organogel electrode material prepared in Example 1 has the smallest Tafel slope of 62.1 mVdec. -1 This indicates a relatively fast HER reaction kinetic.

[0079] Table 3

[0080]

[0081] The bimetallic organogel electrode material prepared in Example 1, the organometallic gel materials prepared in Comparative Examples 1-2, the organometallic compound materials prepared in Comparative Examples 3-4, and the bimetallic organometallic compound material prepared in Comparative Example 5 were respectively used as electrode active materials and assembled into "three-electrode systems" for hydrogen evolution stability testing. The hydrogen evolution stability was tested at 10 mA cm⁻¹. -2 The electrode voltage change was measured at current density to obtain a hydrogen evolution reaction voltage test graph, as shown below. Figure 12 , Figure 13 and Figure 14 As shown, by Figure 12 It can be seen that the three-electrode system using the bimetallic organic gel electrode material prepared in Example 1 remained stable after 175 hours. Figure 13 It can be seen that after 10 hours of testing, the electrode voltage of the three-electrode system using the organometallic gel material prepared in Comparative Example 1 decreased by 50 mV, the electrode voltage of the three-electrode system using the organometallic gel material prepared in Comparative Example 2 decreased by 52 mV, and the electrode voltage of the three-electrode system using the organometallic compound material prepared in Comparative Example 3 decreased by 88 mV. Therefore, their stability is poor. The three-electrode system using the organometallic compound material prepared in Comparative Example 4 can only operate for 5 hours. Figure 14 It can be seen that the three-electrode system using the bimetallic organic compound material prepared in Comparative Example 5 only stabilized at 293mV after running for 4 hours. After running for another 6 hours, the electrode voltage dropped by 73mV, indicating poor stability.

[0082] The bimetallic organogel electrode material prepared in Example 1 was used as the electrode active material to assemble the aforementioned "three-electrode system" according to a 100 mA cm -2 200mA cm -2 400mA cm -2 and 200mA cm -2 The current density was sequentially cycled periodically, with each current density operating for 5 hours, to test the electrode voltage stability at different current densities. Figure 15 As shown, Figure 15 Potential diagrams of the bimetallic organogel electrode materials prepared in Example 1 at different current densities are shown below. Figure 15 It can be seen that the three-electrode system using the bimetallic organic gel electrode material prepared in Example 1 still maintains stability at 65 hours of cycling under different current densities, which proves that the bimetallic organic gel electrode material prepared in Example 1 has excellent durability and superior rate performance in HER.

[0083] According to the literature (Exceptional catalytic activity of oxygen evolution reaction via two-dimensional graphene multilayer confined metal-organic frameworks, Nature Communications, 13, Article number: 6171 (2022)), the oxygen evolution reaction occurs in the voltage range of 1.2–2.0 V (versus: RHE). Figure 16 The oxygen evolution reaction-polarization curves (OER-LSV) of the bimetallic organogel electrode materials prepared in Examples 1-3 are shown. Figure 16 It can be seen that at a current density of 10 mA cm⁻¹ -2At that time, the oxygen evolution overpotential (oxygen evolution overpotential = abscissa value - 1.23) of the bimetallic organic gel electrode material prepared in Example 1 was 306mV, the oxygen evolution overpotential of the bimetallic organic gel electrode material prepared in Example 2 was 345mV, and the oxygen evolution overpotential of the bimetallic organic gel electrode material prepared in Example 3 was 360mV.

[0084] Figure 17 The images show the EIS impedance test results of the bimetallic organogel electrode materials prepared in Examples 1-3 and the metal-organic gel materials prepared in Comparative Examples 1-2. The results were analyzed using Zview software. Figure 17 Impedance fitting analysis revealed that the charge transfer resistance (R) of the bimetallic organic gel electrode material prepared in Example 1 was... ct The charge transfer resistance (R) of the bimetallic organic gel electrode material prepared in Example 2 is 12.0 Ω. ct The charge transfer resistance (R) of the bimetallic organic gel electrode material prepared in Example 3 is 14.4 Ω. ct The charge transfer resistance (R) of the metal-organic gel material prepared in Comparative Example 1 is 17.5 Ω. ct The charge transfer resistance (R) of the metal-organic gel material prepared in Comparative Example 2 is 26.1 Ω. ct The charge transfer resistance was 32.6 Ω. Among them, the bimetallic organogel electrode material prepared in Example 1 had the lowest charge transfer resistance, and therefore the bimetallic organogel electrode material prepared in Example 1 had the highest conductivity. This may be because the metal-induced coordination environment introduces holes, which can effectively adjust the conductivity of the bimetallic organogel electrode material. Therefore, the bimetallic organogel electrode material prepared in Example 1 can further adjust its electronic structure and electron cloud distribution through the interaction between bimetallic atoms, thereby improving its conductivity, reducing the adsorption energy of reaction intermediates, and thus improving its catalytic activity.

[0085] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a bimetallic organogel electrode material, characterized in that, Includes the following steps: Transition metal nickel salt and transition metal cobalt salt are dissolved in ethanol to obtain a transition metal salt mixture. Under a nitrogen or inert gas atmosphere, the transition metal salt mixture is added dropwise to a terephthalic acid mixture at 70-90℃, and the reaction is continued at 70-90℃ for 3-5 hours to obtain a colloidal suspension. The suspension is centrifuged to obtain a precipitate, which is washed and vacuum dried to obtain a bimetallic organic gel electrode material. The ratio of nickel in the transition metal nickel salt, cobalt in the transition metal cobalt salt, and terephthalic acid in the terephthalic acid mixture is x:y:(x+y), where x = 1-2 and y = 1-2.

2. The preparation method according to claim 1, characterized in that, The transition metal cobalt salt is cobalt nitrate hexahydrate or cobalt chloride, and the transition metal nickel salt is nickel nitrate hexahydrate or nickel chloride.

3. The preparation method according to claim 1, characterized in that, The ratio of the molar amount of nickel to the volume amount of ethanol in the transition metal nickel salt is (1-2):(20-60), where the molar amount is in mmol and the volume amount is in mL.

4. The preparation method according to claim 1, characterized in that, The terephthalic acid mixture is a mixture of terephthalic acid and dimethyl sulfoxide, and the concentration of terephthalic acid in the terephthalic acid mixture is 0.5-1 mM.

5. The preparation method according to claim 1, characterized in that, Transition metal nickel salts and transition metal cobalt salts were dissolved in ethanol by sonication for 30–60 minutes.

6. The preparation method according to claim 1, characterized in that, The terephthalic acid mixture is first stirred at 70-90°C for at least 30 minutes, and then the transition metal salt mixture is added dropwise to the terephthalic acid mixture at 70-90°C using a hot injection method. The terephthalic acid mixture is kept stirred while the transition metal salt mixture is added dropwise.

7. The preparation method according to claim 1, characterized in that, The nitrogen or inert gas atmosphere is achieved by purging nitrogen or inert gas at least three times, wherein the operation of purging nitrogen or inert gas includes: evacuating to -0.1 to -0.01 MPa and introducing nitrogen or inert gas.

8. The preparation method according to claim 1, characterized in that, The washing operation includes: centrifuging the precipitate 3 to 5 times each with ethanol and dimethyl sulfoxide in sequence; The vacuum drying temperature is 60–90°C, and the vacuum drying time is 12–24 hours.

9. The bimetallic organogel electrode material obtained by the preparation method according to any one of claims 1 to 8.

10. The application of the bimetallic organic gel electrode material according to claim 9 in hydrogen evolution or oxygen evolution.

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