Cobalt-based coordination polymer electrocatalyst crystalline material, preparation method and application thereof

Abstract

The present application relates to the technical field of electrocatalysis, and particularly relates to a cobalt-based coordination polymer electrocatalyst crystalline material and a preparation method and application thereof.The present application provides a cobalt-based coordination polymer electrocatalyst crystalline material and a preparation method and application thereof, and a cobalt-based coordination polymer crystalline material {[Co2(H2O)6(DODDA)]·4H2O} can be prepared by one-pot solvothermal reaction. n The cobalt-based coordination polymer exhibits good electrical characteristics, indicating the potential as an electrode material.The ligand-metal synergistic effect and the redox active ligand can enhance the catalytic activity, and the stability and conductivity can be significantly improved through the design of strong coordination bonds, thereby providing a new paradigm for the rational design of efficient electrocatalysts.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrocatalysis, and particularly relates to a cobalt-based coordination polymer electrocatalyst crystalline material and a preparation method and application thereof. BACKGROUND

[0002] In recent years, developing efficient and stable electrocatalyst materials has become a research hotspot in the field of energy conversion and storage. Cobalt (Co)-based coordination polymers have broad application prospects in the field of electrocatalysis due to their unique electronic structure, controllable coordination environment and rich active sites.

[0003] Although traditional electrocatalysts have excellent performance, their high cost and scarcity limit their large-scale application. In contrast, cobalt-based coordination polymers can achieve an effective balance of catalytic activity, selectivity and stability through the synergistic effect of organic ligands and cobalt centers. Currently, the design of cobalt-based coordination polymers mainly faces challenges such as low electron transport efficiency due to insufficient electrical conductivity, poor structural stability in strong acid / strong base electrolyte, and insufficient exposure of active sites. To address these issues, existing technologies use strategies such as introducing conductive carriers, constructing porous structures or regulating ligand rigidity for optimization, but further breakthroughs are still needed.

[0004] The present application aims to develop a new type of cobalt-based coordination polymer by optimizing the ligand structure and metal cluster arrangement to improve its electrocatalytic activity and durability, providing an innovative solution to the above technical problems. SUMMARY

[0005] The present application aims to develop a new type of cobalt-based coordination polymer by optimizing the ligand structure and metal cluster arrangement to improve its electrocatalytic activity and durability, providing an innovative solution to the above technical problems.

[0006] The present application provides a cobalt-based coordination polymer electrocatalyst crystalline material, wherein the single crystal molecular formula of the cobalt-based coordination polymer electrocatalyst crystalline material is C 14 H 20 Co2N2O 17 , and the chemical formula of the cobalt-based coordination polymer electrocatalyst crystalline material is {[Co2(H2O)6(DODDA)]·4H2O} n .

[0007] The cobalt-based coordination polymer electrocatalyst crystalline material provided by the application is of an orthorhombic system, a space group of Imma, and cell parameters including a = 21.6859(5) Å, b = 25.9506(6) Å, c = 7.2174(2) Å, α = 90.00°, β = 90.00°, and γ = 90.00°.

[0008] The application provides a preparation method of the cobalt-based coordination polymer electrocatalyst crystalline material.

[0009] S1, H4(DODDA) and cobalt nitrate hexahydrate are added into DEF and deionized water to obtain a mixed solution, and after constant-temperature reaction, the reaction product is obtained by standing;

[0010] S2, the reaction product obtained in S1 is cooled and crystallized, and after the crystallized product is sequentially washed, filtered and dried, the cobalt-based coordination polymer electrocatalyst crystalline material is obtained.

[0011] According to the preparation method provided by the application, the H4(DODDA) in S1 is 1-(3,5-dicarboxyphenyl)-4-oxo-1,4-dihydro-pyridazine-3,5-dicarboxylic acid, and the structural formula of the H4(DODDA) is as follows:

[0012] .

[0013] According to the preparation method provided by the application, the mass-volume ratio of the H4(DODDA), cobalt nitrate hexahydrate, DEF and deionized water in S1 is 0.1 mmol: 0.1 mmol: 1.8-2.2 mL: 0-0.5 mL.

[0014] According to the preparation method provided by the application, the temperature of the constant-temperature reaction in S1 is 80-95 ℃, the time of the constant-temperature reaction is 45-50 h, and the time of the standing is 12 h.

[0015] According to the preparation method provided by the application, the washing agent for the washing in S2 is deionized water, the filtering is reduced-pressure filtering, the temperature of the drying is 40 ℃, and the time of the drying is 2-4 h.

[0016] The application further provides an application of the cobalt-based coordination polymer electrocatalyst crystalline material, and the cobalt-based coordination polymer electrocatalyst crystalline material is used for electrocatalytic water oxidation.

[0017] The application obtains a cobalt-based coordination polymer by a solvothermal method using H4(DODDA) organic ligand and cobalt salt, and the molecular formula of the cobalt-based coordination polymer crystalline material is {[Co2(H2O)6(DODDA)]·4H2O}n which is connected by Co(II) ions as connecting nodes and H4(DODDA) ligands as bridging ligands; the asymmetric unit contains two Co(II) ions with different coordination modes, one deprotonated DODDA 4- ligands, six monodentate water molecules and four lattice water molecules, the Co1 ion center is connected with two carboxyl oxygens of H4(DODDA) ligand and four monodentate water molecules, both Co1 and Co2 ions are six-coordinated structures, but the coordination environment of Co1 is different from that of Co2, the Co2 ion is connected with two monodentate water molecules and four oxygen atoms from carbonyl and carboxyl. Among them, adjacent Co1 ions and two deprotonated tetracarboxyl ligands form a "H" type secondary structure unit through "head-to-head" chelation coordination, and the secondary structure unit connects different Co2 ions through a four-connected mode to form a horizontally placed ladder-shaped one-dimensional chain. The one-dimensional chains form a three-dimensional supramolecular structure through a large number of intermolecular hydrogen bonds.

[0018] Compared with the prior art, the present application has the following advantages:

[0019] The present application provides a cobalt-based coordination polymer electrocatalyst crystalline material and a preparation method and application thereof. The Co(II) ion coordination polymer crystalline material can be prepared by one-pot solvothermal reaction. The cobalt-based coordination polymer exhibits good electrical properties, indicating its potential as an electrode material. The ligand-metal synergistic effect and redox active ligand can enhance the catalytic activity, and the strong coordination bond design can significantly improve the stability and conductivity, providing a new paradigm for the rational design of efficient electrocatalysts. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a single molecule graph of the cobalt-based coordination polymer;

[0021] Figure 2 It is an "H" type structure formed by the cobalt-based coordination polymer;

[0022] Figure 3 It is a simplified structure formed by the cobalt-based coordination polymer;

[0023] Figure 4 It is a one-dimensional chain structure of the cobalt-based coordination polymer;

[0024] Figure 5 It is a three-dimensional supramolecular structure of the cobalt-based coordination polymer;

[0025] Figure 6 It is an IR graph of the cobalt-based coordination polymer;

[0026] Figure 7 It is an XRD graph of the cobalt-based coordination polymer;

[0027] Figure 8 polarization curve graph for the cobalt-based coordination polymer;

[0028] Figure 9 electrochemically active surface area graph for the cobalt-based coordination polymer;

[0029] Figure 10 electrochemical impedance graph for the cobalt-based coordination polymer;

[0030] Figure 11 Tafel slope graph for the cobalt-based coordination polymer. DETAILED DESCRIPTION

[0031] Example 1

[0032] The present embodiment provides a preparation method of H4(DODDA), and the specific steps are as follows:

[0033] S1, 12.00 g of 5-amino isophthalic acid diethyl ester was dissolved in 110 mL of distilled water, 50 mL of concentrated hydrochloric acid and 20 mL of NaNO2 solution with a concentration of 3 mol / L were added dropwise under ice bath at 0°C, and a yellow clear diazonium salt solution was obtained;

[0034] S2, 0.15 mol of sodium acetate was dissolved in 300 mL of distilled water and 300 mL of anhydrous ethanol under ice bath and stirred for 15 min, then 11.30 g of 1,3-propanedione diethyl ester was added, and the stirring was continued for 15 min, then the diazonium salt solution prepared in S1 was slowly added, and the reaction was continued for 2 hours, the filter cake was washed to neutral, and dried at room temperature to obtain 2-(2-(3,5-diethoxycarbonyl phenyl)hydrazyl)-3-oxoglutaric acid diethyl ester;

[0035] S3, 2-(2-(3,5-diethoxycarbonyl phenyl)hydrazyl)-3-oxoglutaric acid diethyl ester obtained in S2 was dissolved in toluene, 6.19 g of DMF-DMA (N,N-dimethylformamide dimethyl acetal) was added dropwise, and then the reaction was carried out at 100°C for 12h, and toluene was removed by concentration to obtain black red viscous material 1-(3,5-diethoxycarbonyl phenyl)-4-oxo-1,4-dihydro pyridazine-3,5-dicarboxylic acid diethyl ester; N N

[0036] ​​S4. Dissolve the diethyl 1-(3,5-diethoxycarbonylphenyl)-4-oxo-1,4-dihydropyridazine-3,5-dicarboxylate obtained in S3 in 100 mL of distilled water, add 16.64 g of NaOH solid and stir, heat the reaction system to 60 °C and react for 3 h, cool to room temperature, add 150 mL of distilled water to the system, add HCl solution to adjust the pH to 2, filter, wash the filter cake to neutrality, and dry to obtain 1-(3,5-dicarboxyphenyl)-4-oxo-1,4-dihydropyridazine-3,5-dicarboxylic acid, i.e., H4(DODDA).

[0037] The preparation steps are specifically shown in the following formula:

[0038] .

[0039] Example 2

[0040] This embodiment provides a cobalt-based coordination polymer electrocatalyst crystalline material, comprising the following steps:

[0041] S1, 0.1 mmol of cobalt nitrate hexahydrate, 0.1 mmol of 1-(3,5-dicarboxyphenyl)-4-oxo-1,4-dihydropyridazine-3,5-dicarboxylic acid (H4(DODDA)) and 1.5 mL N , N -diethylformamide (DEF) and 0.5 mL of deionized water were mixed to obtain a mixture, and the mixture was subjected to solvothermal reaction at 90 °C in a glass scintillation vial for 45 h and allowed to stand for 12 h to obtain a reaction product;

[0042] S2. The reaction product was naturally cooled and crystallized, rinsed with deionized water and filtered under reduced pressure to obtain transparent block crystals. The crystals were placed in an oven at 40 °C for 3 h to obtain the cobalt-based coordination polymer 1 with a yield of about 73.4%.

[0043] Example 3

[0044] This embodiment provides a cobalt-based coordination polymer electrocatalyst crystalline material, comprising the following steps:

[0045] S1. 0.1 mmol of cobalt nitrate hexahydrate, 0.1 mmol of H4(DODDA), and 1.8 mL of DEF were mixed to obtain a mixture. The mixture was subjected to a solvothermal reaction at 95°C in a glass scintillation vial for 48 h, and allowed to stand for 12 h to obtain a reaction product.

[0046] S2. The reaction product was naturally cooled and crystallized, rinsed with deionized water and filtered under reduced pressure to obtain transparent block crystals. The crystals were placed in an oven at 40 °C for 4 h to obtain cobalt-based coordination polymer 2 with a yield of about 68.1%.

[0047] Example 4

[0048] The present example provides a cobalt-based coordination polymer electrocatalyst crystalline material, comprising the following steps:

[0049] S1, 0.1 mmol of cobalt nitrate hexahydrate, 0.1 mmol of H4(DODDA) and 2.2 mL of DEF were mixed to obtain a mixture, and the mixture was placed in a glass scintillation vial and subjected to a solvothermal reaction at a temperature of 85°C for 50 h. After standing for 12 h, a reaction product was obtained;

[0050] S2, the reaction product was naturally cooled and crystallized, washed with deionized water and filtered under reduced pressure to obtain transparent block-shaped crystals. After being placed in an oven at a constant temperature of 40°C for 4 h, a cobalt-based coordination polymer 3 was obtained, with a yield of about 68.5%.

[0051] Example 5

[0052] The cobalt-based coordination polymer 1 prepared in Example 2 was taken for characterization, and the process was as follows:

[0053] (1) Crystal structure determination of the cobalt-based coordination polymer 1

[0054] A single crystal with a suitable size of 0.36 x 0.28 x 0.25 mm 3 was selected under a microscope and subjected to an X-ray diffraction experiment at room temperature. The diffraction data were collected on a Bruker-ApexП X-ray single crystal diffractometer, using monochromated Mo-Kα rays (λ = 0.71073 Å) with a ω-2θ scanning mode. All data were corrected by factor and empirical absorption, and the crystal structure was solved by a direct method using a program, with hydrogen atoms determined by difference Fourier synthesis and fixed at the best calculated positions. Using a program SHELX-97, all non-hydrogen atoms and their anisotropic thermal parameters were corrected by full-matrix least squares method based on. The detailed crystal determination data are shown in Table 1, the bond length and bond angle data are shown in Table 2, and the crystal structure is shown in Figures 1-5 .

[0055] Table 1

[0056]

[0057] Table 2

[0058]

[0059] Symmetry code: 1 1 / 2-X,1 / 2-Y,3 / 2-Z; 2 +X,1 / 2-Y,+Z;

[0060] In Table 1, a, b, and c represent the edge lengths of the crystal in the directions of the three crystal axes, respectively; α, β, and γ represent the angles between a and b, a and c, and b and c, respectively; Z is the number of molecules contained in the unit cell; the diffraction index range of the limiting factor is (h, k, l); F(000) is the number of electrons in the unit cell; Final R indices [I>2σ(I)] is the residual factor R value for the observable diffraction point; R is the non-weighted consistency factor; R1 and wR2 are both weighted consistency factors;

[0061] In the first row of Table 2, Co(1) refers to Co atom 1 in the single crystal of the cobalt-based coordination polymer electrocatalyst crystalline material 1, O(3) refers to O atom 3 in the single crystal of the cobalt-based coordination polymer electrocatalyst crystalline material 1, Co(1)-O(3) represents the bond length between Co atom 1 and O atom 3, and the bond length is 1.119±2, where 2 is the standard deviation; O(3)-Co(1)-O(3) 1 It represents the bond angle between O atom 3, Co atom 1 and the symmetric atom 1 of O atom 3, and its bond angle is 81.26±13;

[0062] (1) IR spectrum characterization

[0063] Figure 6 This is the IR spectrum of the cobalt-based coordination polymer. The sample infrared spectrum data was collected from 4000 to 400 cm -1 , using KBr pellets.

[0064] Depend on Figure 6 It can be seen that the cobalt coordination polymer crystalline material 1 has a peak at 3162 cm -1 There is a strong broad absorption peak at 1608~1562 cm, which is the stretching vibration peak of OH group. -1 The peaks at 1700 are the asymmetric and symmetric stretching vibrations of the carbonyl group, the peak at 1700 is the stretching vibration peak of the carboxyl group, and the peak at 1289 is the vibration peak of the C=N bond.

[0065] The molecular formula of the cobalt-based coordination polymer is {[Co2(H2O)6(DODDA)]∙4H2O} n .

[0066] (2) Phase purity characterization of cobalt-based coordination polymers

[0067] The powder XRD characterization results of the cobalt-based coordination polymer using a Bruker / D8Advance X-ray diffractometer showed that it has reliable phase purity, which provides a guarantee for its application as a catalyst, such as Figure 7 shown.

[0068] (3) Electrocatalytic characterization of cobalt-based coordination polymers

[0069] In order to evaluate the electrochemical ability of the cobalt-based coordination polymer, linear sweep voltammetry (LSV) test was carried out in a three-electrode environment consisting of ITO conductive glass, carbon rod, saturated calomel electrode, with 0.5 mol / L Na2SO4 as electrolyte, at a scanning speed of 5 mV / s, and the polarization curve was drawn as shown in

[0070] The cobalt-based coordination polymer powder was coated on the surface of ITO conductive glass with an area of 1.0 cm 2 , and linear sweep voltammetry (LSV) test was carried out with 0.5 mol / L Na2SO4 as electrolyte, at a scanning speed of 5 mV / s, and the polarization curve was drawn as shown in Figure 8

[0071] A series of cyclic voltammetry (CV) tests were carried out at a scanning speed range of 50-100 mV / s, with an interval of 10 mV / s, to obtain the linear relationship between current density difference (Δj / 2) and scanning speed, and the size of double-layer capacitance (C dl ) was used to estimate the electrochemically active surface area (ECSA), and the C dl size of the cobalt-based coordination polymer was 21.12 mF / cm 2 , as shown in Figure 9

[0072] Figure 10 The impedance (Z') value of the cobalt-based coordination polymer was shown. In addition, electrochemical impedance spectroscopy (EIS) was used to characterize the kinetics of the interface reaction in the OER process, and by this method, the charge transfer resistance (Rct) of the cobalt-based coordination polymer could be obtained by Nyquist plot fitting, which indicated that the coordination polymer had the potential to be used as an electrocatalyst. Tafel slope was used to describe the relationship between overpotential and current density in the electrocatalytic process, and the kinetics of the reaction electrocatalyst in the electrocatalytic process, as shown in Figure 11

[0073] The cobalt-based coordination polymer showed high electrocatalytic performance, which could be used as a high-efficiency catalytic semiconductor material, and provided new progress for the construction of new cobalt-based coordination polymers and their performance in electrocatalysis.

[0074] The above is only a preferred embodiment of the present application, and does not limit the present application. Any simple modification, change and equivalent change made according to the technical essence of the application to the above embodiment are still within the protection scope of the technical solution of the present application.​​​

Claims

1. A cobalt-based coordination polymer electrocatalyst crystalline material, characterized in that: The single crystal molecular formula of the cobalt-based coordination polymer electrocatalyst crystalline material is C 14 H 20 Co2N2O 17 The chemical formula of the cobalt-based coordination polymer electrocatalyst crystalline material is {[Co2(H2O)6(DODDA)]·4H2O} n The cobalt-based coordination polymer electrocatalyst crystalline material is an orthorhombic crystal system with a space group of Imma. The unit cell parameters include a=21.6859(5) Å, b=25.9506(6) Å, c=7.2174(2) Å, α= 90.00°, β= 90.00° and γ= 90.00°. The DODDA is deprotonated H4(DODDA), and the H4(DODDA) is 1-(3,5-dicarboxyphenyl)-4-oxo-1,4-dihydropyridazine-3,5-dicarboxylic acid. The structural formula of the H4(DODDA) is: 。 2. A method for preparing the cobalt-based coordination polymer electrocatalyst crystalline material according to claim 1, characterized in that: The following steps are involved: S1. Add H4(DODDA) and cobalt nitrate hexahydrate to DEF and deionized water to obtain a mixed solution, keep the solution at a constant temperature for sufficient reaction, and then allow the solution to stand to obtain a reaction product; S2. Cooling the reaction product obtained in S1 to crystallize, and washing, filtering and drying the crystallized product in sequence to obtain a cobalt-based coordination polymer electrocatalyst crystalline material.

3. The preparation method according to claim 2, characterized in that The mass volume ratio of H4(DODDA), cobalt nitrate hexahydrate, DEF and deionized water described in S1 is 0.1 mmol:0.1 mmol:1.8-2.2 mL:0-0.5 mL.

4. The preparation method according to claim 2, characterized in that The temperature of the constant temperature full reaction in S1 is 80-95° C., the time of the constant temperature full reaction is 45-50 h, and the standing time is 12 h.

5. The preparation method according to claim 2, characterized in that The rinsing agent in S2 is deionized water, the filtration is reduced-pressure filtration, the drying temperature is 40° C., and the drying time is 2 to 4 hours.

6. An application of the cobalt-based coordination polymer electrocatalyst crystalline material according to claim 1, characterized in that: The cobalt-based coordination polymer electrocatalyst crystalline material is used for electrocatalytic water oxidation.

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