Preparation of binuclear nickel-based metal organic framework material and application of binuclear nickel-based metal organic framework material in electro-catalysis benzyl alcohol oxidation and hydrogen production

Abstract

The invention discloses preparation of a binuclear nickel-based metal organic framework material and application of the binuclear nickel-based metal organic framework material in electro-catalysis benzyl alcohol oxidation and hydrogen production. The invention relates to a porous metal organic framework material, in particular to a porous metal organic framework material which is obtained by direct coordination growth of organic ligands 1, 2, 4, 5-tetra (4-carboxyphenyl) benzene and nickel perchlorate hexahydrate through a hydrothermal method, and a solvent system is a mixed solution composed of water, N, N-dimethylacetamide and HBF4. When the Co < 0.01 > Ni < 0.04 >-MOF catalyst is used as a catalyst for electrocatalytic benzyl alcohol oxidation reaction, it is found that the Co < 0.01 > Ni < 0.04 >-MOF catalyst has excellent oxidation activity, after the second metal Co is introduced, the Co < 0.01 > Ni < 0.04 >-MOF catalyst has more excellent benzyl alcohol oxidation activity and hydrogen evolution activity, BOR can be driven only by 1.39 V of overpotential in 1 M KOH + 0.1 M BA, and the Co < 0.01 > Ni < 0.04 >-MOF catalyst has relatively excellent stability under large current. The high durability is shown within 10000 s, and the current retention rate can still be maintained to be 90% or above after electrolysis is conducted for 10000 s.

Description

Technical Field

[0001] The present invention relates to a novel metal organic framework material (Ni-MOF) formed by using 1,2,4,5-tetrakis(4-carboxyphenyl)benzene as an organic ligand and transition metal nickel as a metal center. Ni-MOF exhibits excellent benzyl alcohol and hydrogen evolution activity through the test of preparing catalyst electrode materials. The structural advantage of the metal organic framework template is utilized, and on this basis, a second metal Co is introduced through a doping strategy. It is found through experiments that the introduction of Co can effectively adjust the electronic structure of Ni-MOF, thereby improving the electrochemical activity. Background Art

[0002] As a green, clean and efficient renewable energy, hydrogen energy is regarded as the key to future energy transformation due to its high energy density and the combustion product is only water. Electrocatalytic water splitting is a key step in the preparation of hydrogen, and hydrogen and oxygen evolution have always been a hot topic in the field of catalysis. However, in the traditional water electrolysis process, the hydrogen evolution reaction (HER) occurs at the cathode and the oxygen evolution reaction (OER) occurs at the anode. Compared with HER, OER is a relatively complex four-electron transfer process. Its reaction kinetics are slow in nature and its theoretical potential is high (1.23 V vs. RHE), which leads to a large overpotential for driving it, greatly reducing energy conversion. So we break the traditional thinking and replace OER with thermodynamically more favorable small molecule oxidation reactions to construct a hybrid water hydrogen production system. These organic oxidation reactions can not only reduce the battery voltage of hydrogen production, but also produce value-added products and can be coupled with the cathode hydrogen evolution reaction to more effectively improve the energy utilization efficiency.

[0003] MOFs are metal organic framework compounds, which are interconnected by inorganic metal centers (metal ions or metal clusters) and bridging organic ligands through self-assembly to form a type of crystalline porous material with a periodic network structure. At present, a metal organic framework material constructed by the coordination of metal ions or metal clusters and organic ligands has extremely high specific surface area, coordinated pore size, adjustable pore size and diversity of skeleton components, and is therefore considered to be an extremely important electrocatalyst. MOFs metal organic framework materials have attracted much attention due to their unique structure, such as high specific surface area, coordinated pore size, adjustable pore size and diversity of skeleton components. In recent years, metal organic frameworks (MOFs) have been widely used in the field of electrocatalysis as a catalyst. This is because MOFs have a large specific surface area and redox ability, providing abundant active sites for electrocatalytic reactions. The starting point of this patent is the performance exploration of a newly synthesized Ni-MOF for benzyl alcohol oxidation and hydrogen evolution reaction, and the construction of a bimetallic MOF catalyst to further explore its performance exploration for benzyl alcohol oxidation and hydrogen evolution. Summary of the invention

[0004] The present invention provides a method for synthesizing a metal organic framework material (Ni-MOF) using 1,2,4,5-tetrakis(4-carboxyphenyl)benzene as a ligand and transition metal nickel as a metal center. Its general chemical formula is Ni2C 34 H 16 O9.

[0005]

[0006] The compound structure is as follows: Weigh the ligand 1,2,4,5-tetrakis(4-carboxyphenyl)benzene, nickel perchlorate hexahydrate, deionized water, N,N-dimethylacetamide (DMA), and 37% HBF4 ultrasonic dispersion, then add them into a glass bottle, seal it, and heat the reaction under the solvent at 100-120°C for 18-48 hours, and cool it to room temperature at a constant rate of 2-3°C / h to obtain green block crystals. The dried material was used to prepare the electrode material to test the benzyl alcohol oxidation and hydrogen evolution performance.

[0007] The molar ratio of the organic ligand 1,2,4,5-tetrakis(4-carboxyphenyl)benzene and nickel perchlorate hexahydrate is 1:1-1:4; the volume ratio of N,N-dimethylacetamide (DMA) and deionized water is 3:1-5:1, the mass concentration is 37%, the volume of HBF4 is 0.1-1ml, and the pH is adjusted to 5-6.5. The solvent thermal reaction conditions are 100-120°C and the reaction time is 18-48 hours.

[0008] More preferably, the molar ratio of the organic ligand 1,2,4,5-tetrakis(4-carboxyphenyl)benzene to nickel perchlorate hexahydrate is 1:2; the volume ratio of N,N-dimethylacetamide (DMA) to deionized water is 4:1, and the pH is adjusted to 5.3. The solvent thermal reaction conditions are 120°C and the reaction time is 48 hours.

[0009] Cobalt metal salt is also introduced into the binuclear nickel-based metal organic framework material to prepare a binuclear nickel-cobalt-based metal organic framework material.

[0010] The organic ligand 1,2,4,5-tetrakis(4-carboxyphenyl)benzene and nickel metal salt and cobalt metal salt are added to a mixed solution of water, N,N-dimethylacetamide and HBF4, and a binuclear nickel-cobalt based metal organic framework material is obtained through a solvothermal reaction.

[0011] The molar ratio of nickel to cobalt in the nickel metal salt and the cobalt metal salt is 1:1-9. In some embodiments, it can be any one of 1:1, 1:4, and 1:9.

[0012] The nickel-based metal organic framework material also includes a chemical formula of Ni2C34 H 16 O9 crystalline material, wherein the room temperature involved in the present invention refers to the ambient temperature under normal pressure.

[0013] In some embodiments, the binuclear nickel-cobalt-based metal organic framework material includes Co 0.01 Ni 0.04 -MOF, Co 0.04 Ni 0.04 -MOF, Co 0.045 Ni 0.04 -Any one of MOFs.

[0014] The binuclear nickel-based metal organic framework material prepared by the method is used as an electrocatalyst in the oxidation or hydrogen evolution of benzyl alcohol.

[0015] The nickel-based metal organic framework material is used as an electrocatalyst to catalyze the oxidation of benzyl alcohol and hydrogen evolution.

[0016] The crystal synthesized in the present invention is measured by using a small molecule single crystal X-ray diffractometer of Rigaku Co., Ltd. of Japan. The Mo Kα rays monochromatized by a graphite monochromator are used to measure the diffraction intensity and unit cell parameters at 293K. The collected data are subjected to empirical absorption correction by using a scanning technique. The obtained results are analyzed by a direct method using the Shelxtl-97 program and corrected by the full matrix least squares method. The crystallographic data are shown in Crystal Parameter Table 1.

[0017] Table 1 Crystallographic parameters

[0018] Note: The single crystal synthesized by the present invention is very pure under an optical microscope, but the data quality may be affected by temperature conditions and instability in air during the test, resulting in a high R factor during the test. The present invention actively takes corresponding measures and tests under nitrogen low temperature conditions, but still cannot obtain very complete crystal data. At the same time, we also adjusted the growth environment of the crystal and found that the crystal synthesized by the original scheme is the purest, but the data quality is still not very satisfactory. We are very sorry for this and will keep trying until we get a single crystal structure with complete data quality.

[0019] When it was used as a catalyst for the electrocatalytic oxidation of benzyl alcohol, it was found to have excellent oxidation activity, and after the introduction of the second metal Co, Co 0.01 Ni 0.04-MOF catalyst has more superior benzyl alcohol oxidation activity and hydrogen evolution activity. In 1 M KOH+0.1 M BA, only an overpotential of 1.39 V is needed to drive BOR. It also has excellent stability under high current and shows strong durability within 10,000 s. After 10,000 s of electrolysis, the current retention rate can still be maintained above 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 : This is a unit structure diagram of the crystalline metal organic framework material (Ni-MOF) synthesized in Example 4.

[0021] Figure 2 : A three-dimensional stacking diagram of the crystalline metal-organic framework material (Ni-MOF) synthesized in Example 4.

[0022] Figure 3 : The Ni-MOF prepared in Example 4 and the optimal target sample of Co-doped Ni-MOF in Example 5 (Co 0.01 Ni 0.04 -MOF).

[0023] Figure 4 : The optimal target sample (Co) of the Ni-MOF prepared by the ligand 1,2,4,5-tetrakis(4-carboxyphenyl)benzene and Example 4 and the Co-doped Ni-MOF of Example 5 0.01 Ni 0.04 -MOF).

[0024] Figure 5 : Ni-MOF prepared in Example 4 and Co prepared in Example 5 0.01 Ni 0.04 -Thermogravimetric diagram of MOF.

[0025] Figure 6 : Scanning electron microscopy (SEM) image of the Ni-MOF prepared in Example 4.

[0026] Figure 7 : LSV diagrams of the Ni-MOF prepared in Example 4 and the Co-doped Ni-MOF (Co:Ni-MOF) different from that in Example 5 in 1 M KOH.

[0027] Figure 8 : LSV diagrams of the Ni-MOF prepared in Example 4 and the Co-doped Ni-MOF (Co:Ni-MOF) different from that in Example 5 in 1 M KOH + 0.1 M BA.

[0028] Fig. 9 : The optimal target sample Co of Example 5 0.01 Ni 0.04-LSV plots of MOF in 1 M KOH+0.1 M BA and 1 M KOH.

[0029] Fig.10 : The optimal target sample of Example 5 (Co 0.01 Ni 0.04 Figure 5. HPLC peak diagram of 2-MOF electrolyzed at different time periods.

[0030] Fig.11 : is the optimal target sample of Example 5 (Co 0.01 Ni 0.04 -MOF) electrolysis at different time periods for benzyl alcohol conversion and product generation.

[0031] Fig.12 : is the optimal target sample of Example 5 (Co 0.01 Ni 0.04 -MOF) electrolysis of benzyl alcohol consumption rate and yield at different electrode potentials.

[0032] Fig.13 : is the optimal target sample of Example 5 (Co 0.01 Ni 0.04 Faradaic efficiency diagram of benzyl alcohol electrolysis using 2-MOF (-MOF) at different electrode potentials.

[0033] Fig.14 : Ni-MOF prepared in Example 4 and its optimal target sample (Co 0.01 Ni 0.04 -MOF) in 1 MKOH for hydrogen evolution performance.

[0034] Fig.15 : Pictures of Ni-MOF crystals synthesized using different anion nickel salts in Example 4.

[0035] Fig.16 : Crystal picture of the crystalline metal organic framework material (Ni-MOF) synthesized in Example 4. DETAILED DESCRIPTION

[0036] Example 1 Weigh 0.04 mmol 1,2,4,5-tetrakis(4-carboxyphenyl)benzene, 0.04 mmol nickel sulfate, 1 ml deionized water in equal amounts and pack them in 8 bottles. Number each bottle from 1 to 8, and add 4 ml N,N-dimethylacetamide (DMA), 4 ml DMF, 4 ml ethanol, 4 ml methanol, 4 ml acetonitrile, 4 ml isopropanol, 4 ml ethylene glycol, 4 ml DMSO. The reaction is carried out in a sealed 20 ml glass bottle. After ultrasonication for 15 min, place it in a sealed oven, react at 100 ° C for 48 hours, and cool to room temperature at a constant rate of 2~3 ° C / h. It is found that there are no crystals in the 8 bottles, and they are all in a precipitated state.

[0037] Example 2 Weigh 0.04 mmol 1,2,4,5-tetrakis(4-carboxyphenyl)benzene, 0.04 mmol nickel sulfate, 1 ml deionized water in equal amounts and pack them in 8 bottles. Number each bottle from 1 to 8, and add 4 ml N,N-dimethylacetamide (DMA), 4 ml DMF, 4 ml ethanol, 4 ml methanol, 4 ml acetonitrile, 4 ml isopropanol, 4 ml ethylene glycol, and 4 ml DMSO. Add 0.3 ml HBF4 (mass concentration is 37%) to each bottle, adjust the pH to 5.3, and react in a sealed 20 ml glass bottle. After ultrasonication for 15 min, place it in a sealed oven, react at 100 ° C for 48 hours, and cool to room temperature at a constant rate of 2~3 ° C / h. It was found that fine polycrystals were produced in bottle No. 1, 3 and 7 were precipitates, and the rest were turbid solutions.

[0038] Example 3 Weigh equal amounts of 0.04 mmol 1,2,4,5-tetrakis(4-carboxyphenyl)benzene, 0.04 mmol nickel sulfate, and 1 ml of deionized water, and divide them into 9 bottles numbered 1 to 9. Add 4 ml N,N-dimethylacetamide (DMA) to bottles 1 to 3, and add 0.1, 0.3, and 0.7 ml of 37% HBF4, respectively; add 4 ml ethanol to bottles 4 to 6, and add 0.1, 0.3, and 0.7 ml of 37% HBF4, respectively; add 4 ml ethylene glycol to bottles 7 to 9, and add 0.1, 0.3, and 0.7 ml of 37% HBF4, respectively. The reaction was carried out in a sealed 20 ml glass bottle. After ultrasonication for 15 min, the bottle was placed in a sealed oven, reacted at 100 °C for 48 hours, and cooled to room temperature at a constant rate of 2-3 °C / h. It was found that the crystals in bottle No. 1 (containing 0.1 ml of HBF4) were very small and almost invisible, the crystals in bottle No. 2 were uneven in size and had cracks on the surface, and bottle No. 3 contained a clear solution; among bottles No. 4-9, bottle No. 6 contained a blue clear solution, bottles 4, 5, and 7 were precipitates, and bottles 8 and 9 were similar to colloidal solutions.

[0039] Example 4 Set up 5 bottles, weigh 0.01mmol, 0.015mmol, 0.02mmol, 0.025mmol, and 0.035mmol of the ligand 1,2,4,5-tetrakis(4-carboxyphenyl)benzene, respectively, add 0.04mmol nickel sulfate, add 1ml deionized water, 4ml DMA, and 0.3ml 37% HBF4 in sequence, and the reaction is carried out in a sealed 20ml glass bottle. After ultrasonication for 15 min, place it in a closed oven, react at 100℃ for 48 hours, and cool to room temperature at a uniform rate of 2-3℃ / h. It was found that the vials with 0.01mmol and 0.015mmol ligands were polycrystalline with uneven shapes and sizes; the vial with 0.02mmol contained polycrystalline, some of which were spherulites and some of which were regular block crystals with some cracks on the surface of the crystals; the vial with 0.035mmol contained no crystals but precipitated; the crystals in the vial with 0.025mmol were mostly light green regular block crystals, and a few had tiny cracks on the surface of the crystals.

[0040] Example 5 Set up 5 bottles, weigh 0.025 mmol 1,2,4,5-tetrakis(4-carboxyphenyl)benzene in equal amounts, weigh 0.04mmol nickel chloride hexahydrate, 0.04mmol nickel nitrate hexahydrate, 0.4mmol nickel sulfate hexahydrate, 0.04mmol nickel acetate tetrahydrate, 0.04mmol nickel perchlorate hexahydrate, add 1 ml of deionized water, 4 ml DMA, 0.3ml 37% HBF4 in sequence, and react in a sealed 20ml glass bottle. After ultrasonication for 15 min, place it in a sealed oven, react at 100℃ for 48 hours, and cool to room temperature at a constant rate of 2~3℃ / h. It was found that crystals were generated in each bottle. Taking the crystals of the vial synthesized with 0.04mmol nickel perchlorate hexahydrate as an example, they are very complete and transparent. Fig.15 , 16 The morphological state of crystal synthesis can be known. Figure 3 It can be seen that the powder diffraction peak of the prepared sample is consistent with the diffraction peak of Ni-MOF simulated by single crystal data. The obtained sample is Ni-MOF, and the crystallographic parameters are shown in Table 1.

[0041] Example 6 0.025 mmol of organic ligand 1,2,4,5-tetrakis(4-carboxyphenyl)benzene and 0.04 mmol of nickel perchlorate hexahydrate were weighed in equal amounts, and different molar amounts of nickel nitrate hexahydrate were added to set up three different ratios of bimetallic Co x Ni yMOF (x:y=0.04:0.04; 0.0045:0.04; 0.01:0.04, x represents the molar amount of cobalt salt, y represents the molar amount of nickel salt), 1 ml of deionized water, 4 ml of DMA, and 0.3 ml of 37% HBF4 were added in sequence, and the reaction was carried out in a sealed 20 ml glass bottle. After ultrasonication for 15 min, it was placed in a sealed oven at 100 ° C for 48 hours, and then cooled to room temperature at a constant rate of 2-3 ° C / h to prepare Co 0.04 Ni 0.04 -MOF, Co 0.0045 Ni 0.04 -MOF, Co 0.01 Ni 0.04 -MOF. Figure 3 It can be seen that the powder diffraction peak of the sample is consistent with the simulated Ni-MOF diffraction peak, indicating that the sample is successfully prepared.

[0042] Example 7 Weigh 5 mg of the porous crystalline metal framework material samples (Ni-MOF and CoxNiy-MOF) collected in Examples 5 and 6 into 2 ml centrifuge tubes, add 0.9 ml isopropanol and 0.1 ml naphthol, and use a pipette to absorb 160 ul of the dispersion and disperse it on both sides of the carbon cloth after ultrasonic treatment for 60 minutes to test the benzyl alcohol oxidation performance. After activating and stabilizing the material in 1.0 M KOH solution, the oxygen evolution performance was measured, and then the benzyl alcohol oxidation curve was measured in 1.0 M KOH + 0.1 M BA. The final sample Co 0.01 Ni 0.04 -MOF only needs an overpotential of 1.38 V to drive the oxidation of benzyl alcohol, such as Figure 7 , Figure 8 The ultimate goal is to 0.01 Ni 0.04 -MOF performance in 1.0 M KOH and 1.0 M KOH + 0.1 M BA was greatly improved at a current density of 10 mA cm -2 When the potential increases by 250mv, Fig. 9 . And the sample (Co 0.01 Ni 0.04 -MOF / CC) was activated and stabilized in 1.0 M KOH solution and then the hydrogen evolution performance was measured. Fig.14 The target sample was tested at a minimum current density of 10 mA cm -2 The performance is relatively excellent, with an overpotential of 131.2mv, but the overpotential is higher at high current density.

[0043] The sample Co 0.01 Ni 0.04 -MOF at 90 mA cm-2 Electrolysis was performed at different current densities for different times, and the electrolyte was taken at each time period. The electrolyte products were analyzed by HPLC. It can be seen that at 250nm, the peaks of benzyl alcohol, benzaldehyde, and benzoic acid changed with time, and their positions were observed in the peak spectrum of HPLC. As the reaction time progressed, it was found that the peak strengths of the three substances changed significantly, such as Fig.10 After 24 h, benzyl alcohol was almost completely converted into benzoic acid, and the content of by-product benzaldehyde was low. Fig.11 At the same time, at different electrode potentials, high benzyl alcohol conversion rate, benzoic acid selectivity and yield were maintained, such as Fig.12 However, its Faradaic efficiency has changed significantly, which may be due to the competitive process of oxygen generation in the catalyst at a higher potential, such as Fig.13 In summary, the introduction of the second metal Co can effectively optimize the electronic structure and improve the conductivity, thereby improving the oxidation performance of the catalyst for benzyl alcohol, accelerating the anode reaction and producing hydrogen at the same time to reduce the energy consumption required for the reaction.

Claims

1. A binuclear nickel-based metal organic framework material, characterized in that: The chemical formula of nickel-based metal organic framework materials is Ni2C 34 H 16 The crystalline material of O9 belongs to the monoclinic system, the space group is P21 / n, the unit cell parameters are: α=90°, β=104°, γ=90°, a=11.3595(12)Å, b=32.390(3)Å, c=14.9944(18)Å.

2. A method for preparing a binuclear nickel-based metal organic framework material, characterized in that: The steps are as follows: adding organic ligand 1,2,4,5-tetrakis(4-carboxyphenyl)benzene and nickel metal salt to a mixed solution of water, N,N-dimethylacetamide and HBF4, and obtaining a binuclear nickel-based metal organic framework material through a solvent thermal reaction.

3. The method for preparing a binuclear nickel-based metal organic framework material according to claim 1, characterized in that: The molar ratio of the ligand 1,2,4,5-tetrakis(4-carboxyphenyl)benzene and the nickel metal salt is 1:1-1:4; the volume ratio of deionized water and DMA is 3:1-4:1, the mass concentration of HBF4 is 37%, and the pH is adjusted to 5-6.

5.

4. The method for preparing a binuclear nickel-based metal organic framework material according to claim 3, characterized in that: The solvent thermal reaction conditions are 100~120℃, and the reaction time is 18~48 hours.

5. The method for preparing a binuclear nickel-based metal organic framework material according to any one of claims 2 to 4, characterized in that: Cobalt metal salt is also introduced into the binuclear nickel-based metal organic framework material to prepare a binuclear nickel-cobalt-based metal organic framework material.

6. The method for preparing a binuclear nickel-based metal organic framework material according to claim 5, characterized in that: The organic ligand 1,2,4,5-tetrakis(4-carboxyphenyl)benzene and nickel metal salt and cobalt metal salt are added to a mixed solution of water, N,N-dimethylacetamide and HBF4, and a binuclear nickel-cobalt based metal organic framework material is obtained through a solvothermal reaction.

7. The method for preparing a binuclear nickel-based metal organic framework material according to claim 6, characterized in that: The molar ratio of nickel to cobalt in the nickel metal salt and the cobalt metal salt is 1:1-9.

8. Use of the binuclear nickel-based metal organic framework material prepared by the method according to any one of claims 2 to 7 as an electrocatalyst for benzyl alcohol oxidation or hydrogen evolution.

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