Preparation method of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by electrolysis of water

Abstract

The present application relates to the preparation of metal organic framework material (MOF) and its application in the field of hydrogen production by electrolysis of water, in particular to the preparation method of MOF-on-MOF structure material derived on MOF for hydrogen production by electrocatalysis. The present application discloses a preparation method of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by electrolysis of water, comprising the following steps: foam nickel cleaning and drying; synthesis of nanosheet MOF; synthesis of composite multi-dimensional doped MOF (MOF-on-MOF); pyrolysis carbonization; phosphating reaction, to obtain a phosphated electrocatalyst. The present application utilizes the strategy of MOF-on-MOF combined with a two-step hydrothermal method, and simultaneously utilizes high-temperature pyrolysis and phosphating, to obtain a phosphated carbon composite porous electrocatalyst with multiple transition metal composites and high specific surface area. The electrocatalyst has excellent HER / OER dual-function electrocatalytic activity, and has high practical value in the field of electrolysis of water.

Description

TECHNICAL FIELD

[0001] The present application relates to the preparation of metal organic framework materials (MOF) and its application in the field of hydrogen production by electrolysis of water, in particular to the preparation method of MOF structure material derived on MOF for hydrogen production by electrocatalysis. BACKGROUND

[0002] The large-scale application of fossil energy as the main energy of the current society has gradually deepened the pollution to the earth's environment. With the development of science and technology, in order to solve the pollution problem, various new energy sources with low pollution have gradually attracted the attention of researchers. Among many new energy sources, hydrogen energy is considered as one of the most practical renewable energy sources due to its renewable and environmental protection advantages.

[0003] Among many hydrogen production methods, water electrolysis is considered as a most promising large-scale high-purity hydrogen production method and is deeply studied by many researchers. The water electrolysis reaction is divided into oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), both of which have complex and slow electron transfer and kinetic processes, and often require additional potential far exceeding the theoretical decomposition voltage value (1.23V) of the reaction to overcome the reaction barrier and achieve the expected hydrogen production efficiency. In recent years, noble metal materials such as Pt, Pd, IrO2 have been found to significantly reduce the water electrolysis reaction barrier and accelerate the reaction kinetics, which are called electrocatalysts. However, due to the low content of noble metals in the earth's crust, the high use cost limits its future application. Therefore, it is of great research significance and engineering value to develop low-cost and high-efficiency dual-function catalysts for water electrolysis hydrogen production.

[0004] Metal organic framework material (MOF) is a kind of porous coordination compound, which is assembled by connecting inorganic nodes with organic ligands. It has attracted wide attention due to its excellent physical and chemical properties. Through the hybrid design idea of multi-dimensional metal organic framework (MOF-on-MOF), hybrid materials of two or more different types of MOF can be obtained. This method directly grows guest MOF on the pre-synthesized host MOF material, and the composition and properties of the guest material and the host MOF are generally different. Therefore, through the MOF-on-MOF strategy, the composition and structural diversity of MOF materials such as pore structure and surface properties can be further increased. Combined with the excellent electrocatalytic activity of transition metal materials such as Mn, Co and Ni, the application scenarios of MOF materials in the field of electrocatalysis can be further expanded. SUMMARY

[0005] The technical problem solved by the present application is to provide a preparation method of high-efficiency dual-function electrocatalytic material for water electrolysis hydrogen production.

[0006] To solve the above technical problems, the application provides a preparation method of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by electrolysis of water, comprising the following steps:

[0007] 1) The foam nickel (NF) is cleaned and dried to obtain cleaned and dried foam nickel;

[0008] 2) Synthesis of nanosheet MOF:

[0009] MnCl2·4H2O is used as a reaction precursor A1, and terephthalic acid (BDC) is used as an organic ligand A2;

[0010] The weight ratio of the reaction precursor A1 to the organic ligand A2 is set to 1.1-1.3:1 (preferably 1.2:1);

[0011] The reaction precursor A1 and the organic ligand A2 are respectively dissolved in an organic solvent I, so as to respectively obtain a reaction precursor A1 solution and an organic ligand A2 solution;

[0012] In a reaction kettle (polytetrafluoroethylene reaction kettle), the reaction precursor A1 solution, the organic ligand A2 solution and a NaOH solution are uniformly stirred and mixed (the stirring time is about 5±2 min), and then the cleaned and dried foam nickel obtained in step 1) is added, and hydrothermal reaction is carried out at 100±10°C for 15±1 h; after cooling to room temperature, the foam nickel after reaction is taken out, cleaned and dried, so as to obtain foam nickel loaded with Mn-BDC-MOF precursor (nanosheet transition metal MOF material grown on the foam nickel, MOF represents metal organic framework);

[0013] 3) Synthesis of composite multi-dimensional doped MOF (MOF-on-MOF):

[0014] Co(NO3)2·6H2O is used as a reaction precursor B1, and 2-methylimidazole is used as an organic ligand B2;

[0015] The weight ratio of the reaction precursor A1 to the transition metal reaction precursor B1 is set to 0.6-0.8:1 (preferably 0.68:1); and the weight ratio of the reaction precursor B1 to the organic ligand B2 is set to 0.8-1:1 (preferably 0.89:1);

[0016] The transition metal reaction precursor B1 and the organic ligand B2 are respectively dissolved in an organic mixed solvent, so as to respectively obtain a transition metal reaction precursor B1 solution and an organic ligand B2 solution;

[0017] In the container, the transition metal reaction precursor B1 solution and the organic ligand B2 solution are uniformly stirred and mixed (the stirring time is about 5±2 min), then the foam nickel loaded with the Mn-BDC-MOF precursor obtained in step 2) is added, and after standing at room temperature for 24±2 h, the reacted foam nickel is taken out, washed and dried to obtain the foam nickel loaded with the multi-dimensional doped MOF;

[0018] 4) Pyrolysis carbonization:

[0019] Under the protection of an inert gas (for example, Ar), the foam nickel loaded with the multi-dimensional doped MOF obtained in step 3) is subjected to a pyrolysis reaction (placed in a tube furnace for pyrolysis reaction), heated to 600-900°C and kept for 3±0.5 h, and then cooled to room temperature to obtain the foam nickel loaded with the MOF-derived carbon-based catalyst material;

[0020] Note: The purpose of the pyrolysis reaction is to carbonize the internal organic matter of the foam nickel loaded with the multi-dimensional doped MOF;

[0021] 5) Phosphating reaction:

[0022] 1 g of sodium hypophosphite particles is placed in a porcelain boat C1, and the foam nickel loaded with the MOF-derived carbon-based catalyst material obtained in step 4) is placed in a porcelain boat C2. The porcelain boat C1 is placed near the gas inlet of the tube furnace, and the porcelain boat C2 is placed near the gas outlet. An inert gas (for example, Ar) is introduced as a protective gas, and the temperature is raised to 300-450°C (preferably 350°C) at a rate of 2°C / min, kept for 2±0.5 h, and then cooled to room temperature to obtain the phosphated electrocatalyst.

[0023] As an improvement of the preparation method of the MOF-on-MOF multi-dimensional metal organic framework material for water electrolysis to produce hydrogen according to the present application, step 2):

[0024] 0.15-0.25 g of MnCl2·4H2O is dissolved in 10 mL of an organic solvent I to obtain a reaction precursor A1 solution; the volume of the organic solvent I used for preparing the organic ligand A2 solution is equal to the volume of the organic solvent I used for preparing the reaction precursor A1 solution.

[0025] The molar concentration of the NaOH solution is 0.35-0.45 M;

[0026] The volume ratio of the reaction precursor A1 solution to the NaOH solution is 10:1.5-3.5.

[0027] As a further improvement of the preparation method of the MOF-on-MOF multi-dimensional metal organic framework material for water electrolysis to produce hydrogen according to the present application, step 2): the organic solvent I is N,N-dimethylformamide (DMF).

[0028] As a further improvement of the preparation method of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by water electrolysis of the present application, step 3) is as follows: the organic mixed solvent is a mixture of methanol and ethanol in equal volume.

[0029] As a further improvement of the preparation method of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by water electrolysis of the present application, step 3) is as follows: 0.25-0.35 g of Co(NO3)2·6H2O is dissolved in 10 mL of the organic mixed solvent to obtain a transition metal reaction precursor B1 solution.

[0030] The volume of the organic mixed solvent used for preparing the organic ligand B2 solution is equal to that used for preparing the transition metal reaction precursor B1 solution.

[0031] As a further improvement of the preparation method of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by water electrolysis of the present application, step 5) is as follows:

[0032] The foam nickel with a size of 2 cm x 3 cm is prepared into a foam nickel loaded with MOF-derived carbon-based catalyst material, and 0.9-1.1 g of sodium hypophosphite is used.

[0033] As a further improvement of the preparation method of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by water electrolysis of the present application:

[0034] The cleaning and drying of step 2) are as follows: ultrasonic cleaning with anhydrous ethanol and deionized water, and drying in a vacuum oven at 80±10℃ for 5±1h.

[0035] The cleaning and drying of step 3) are as follows: cleaning with anhydrous ethanol and deionized water, and drying in a vacuum oven at 80±10℃ for 7±1h.

[0036] As a further improvement of the preparation method of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by water electrolysis of the present application:

[0037] The heating rate of step 4) is 5±0.5℃ / min.

[0038] The heating rate of step 5) is 2±0.2℃ / min.

[0039] As a further improvement of the preparation method of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by water electrolysis of the present application, step 1) is as follows: the foam nickel is cut into a rectangle of 2 x 3 cm 2 , and is ultrasonically cleaned in 3M hydrochloric acid for 30±5min, and then ultrasonically cleaned with anhydrous ethanol and deionized water, and dried in a vacuum oven at 80±10℃ for 1±0.2h.

[0040] As a further improvement of the preparation method of the MOF-on-MOF multi-dimensional metal-organic framework material for hydrogen production by electrolysis of water of the present application, as a preferred:

[0041] The weight ratio of the reaction precursor A1 and the organic ligand A2 is set to 1.2:1;

[0042] The weight ratio of the reaction precursor A1 and the transition metal reaction precursor B1 is set to 0.68:1; and the weight ratio of the reaction precursor B1 and the organic ligand B2 is set to 0.89:1;

[0043] The pyrolysis temperature is 800 DEG C.

[0044] The present application relates to a kind of multi-dimensional MOF derived electrocatalyst material and preparation method thereof by MOF-on-MOF idea preparation, which is mainly composed of Ni, Co, Mn and other transition metal materials and C, P and other inorganic non-metallic materials.

[0045] The present application successfully synthesizes a porous MOF derived bimetallic site phosphorus doped carbon catalyst by adopting two-step hydrothermal method and combining high temperature pyrolysis and gas phase phosphorization, and has the following technical advantages:

[0046] (1) the Mn, Co bimetallic MOF structure is constructed by MOF-on-MOF strategy, and the carbon supported transition metal phosphide is formed after pyrolysis and phosphorization, the structure and composition of the electrocatalyst are finely designed and controlled, which can play excellent HER / OER dual functional catalytic performance, and the overall preparation method has good operability.

[0047] (2) the unique porous structure and composition of MOF-on-MOF can significantly expand the specific surface area of the electrocatalyst, further promote the electrode in the electrolyte and expose the electrochemical active site, and at the same time, the faster reaction kinetics and better charge transfer capacity of the composite transition metal compound are combined, which can significantly improve the performance of the electrocatalyst.

[0048] (3) the bimetallic MOF material is treated by pyrolysis and carbonization and phosphorization, the addition of C and P elements can improve the conductivity of the material, further optimize the electronic structure of the electrocatalyst catalytic active center, and improve the electrocatalytic performance of the catalyst.

[0049] In summary, the present application utilizes the strategy of MOF-on-MOF and two-step hydrothermal method, and utilizes high temperature pyrolysis and phosphorization, to obtain a variety of transition metal composites, and a phosphorized carbon composite porous electrocatalyst with high specific surface area. The electrocatalyst has excellent HER / OER dual functional electrocatalytic activity, and has high practical value in the field of water electrolysis. BRIEF DESCRIPTION OF DRAWINGS

[0050] The specific embodiments of the present application will be further described in conjunction with the drawings.

[0051] Figure 1 is a scanning electron microscope image (SEM photo) of the product of each step in the preparation process of Example 1;

[0052] b is an SEM photo of the Mn-BDC-MOF obtained in step 2), and a is a 30k magnification photo of b;

[0053] d is an SEM photo of ZIF-67 of step 3), and c is a 30k magnification photo of d;

[0054] f is an SEM photo of ZIF-67 / Mn(BDC) obtained in step 3), and e is a 30k magnification photo of f;

[0055] h is an SEM photo of P@C@Mn-Co-MOF / NF obtained in step 5), and g is a 30k magnification photo of h.

[0056] Figure 2 is a scanning electron microscope image (SEM photo) of the MOF-on-MOF multi-dimensional metal organic framework material prepared in Example 2; b is an SEM photo of P@C(600)@Mn-Co-MOF / NF, and a is a 30k magnification photo of b;

[0057] d is an SEM photo of P@C(700)@Mn-Co-MOF / NF, and c is a 30k magnification photo of d;

[0058] f is an SEM photo of P@C(900)@Mn-Co-MOF / NF, and e is a 30k magnification photo of f.

[0059] Figure 3 is an SEM photo of the MOF-on-MOF multi-dimensional metal organic framework material prepared in Comparative Examples 1, 2, and 3;

[0060] b is an SEM photo of P@C@Mn-MOF / NF obtained in Comparative Example 1, and a is a 30k magnification photo of b;

[0061] d is an SEM photo of P@C@Co-MOF / NF obtained in Comparative Example 2, and c is a 30k magnification photo of d;

[0062] f is an SEM photo of P@C@MnCo-MOF / NF obtained in Comparative Example 3, and e is a 30k magnification photo of f.

[0063] Figure 4are the OER / HER linear voltammetry scan (LSV) test result graphs of the MOF-on-MOF multi-dimensional metal organic framework materials prepared in Example 1 and Comparative Examples 1, 2, 3;

[0064] Figure 4 (a) OER process LSV curve, (b) HER process LSV curve.

[0065] Note: NF represents nickel foam, which is a base material. DETAILED DESCRIPTION

[0066] The application will be further described in conjunction with specific examples, but the protection scope of the application is not limited to this:

[0067] Example 1: A preparation method of a phosphorized carbon composite porous Mn-Co MOF electrocatalyst (P@C@Mn-Co-MOF / NF) taking MnCl2·4H2O and Co(NO3)2·6H2O as reaction precursors, which comprises the following steps in sequence:

[0068] 1) Cut the nickel foam into a 2x3 cm rectangle, put it into 3M concentrated hydrochloric acid for ultrasonic treatment for 30 min, then use anhydrous ethanol and deionized water for ultrasonic treatment for 5 min respectively, take it out after drying in an 80℃ vacuum oven for 1 h, and get the cleaned nickel foam, ready for use. 2

[0069] 2) Take 0.198 g of MnCl2·4H2O and 0.166 g of terephthalic acid (BDC), dissolve the two powders in 10 mL of N,N-dimethylformamide (DMF) respectively, stir uniformly to get two solutions, then pour the two solutions into a 50 mL polytetrafluoroethylene reaction kettle, mix, add 2 mL of 0.4M NaOH solution, stir for 5 min, then put the cleaned nickel foam obtained in step 1) into a 100℃ oven for reaction for 15 h, take out the reaction product after cooling, ultrasonic clean with anhydrous ethanol and deionized water for 5 min respectively, dry in an 80℃ vacuum oven for 5 h, and get the nickel foam loaded with Mn-BDC-MOF precursor.

[0070] Note: MOF represents metal organic framework material.

[0071] ​3) Take 0.291 g of Co(NO3)2·6H2O and 0.3283 g of 2-methylimidazole, respectively, and add each to 10 mL of a mixed solvent composed of methanol and ethanol = 1:1 (by volume), and stir to obtain two solutions. Then pour the two solutions into a 50 mL beaker, stir for 5 min, and then place in the foam nickel loaded with the Mn-BDC-MOF precursor obtained in step 2), and let stand at room temperature for 24 h. Then take out, and wash with anhydrous ethanol and deionized water (three times each), and then dry in a vacuum oven at 80°C for 7 h to obtain foam nickel loaded with multi-dimensional doped MOF; that is, foam nickel loaded with ZIF-67 / Mn(BDC).

[0072] Description: This step 3) is to grow ZIF-67 (a type of MOF) on the nanosheet MOF of step 2) to form a composite multi-dimensional doped structure of MOFON MOF.

[0073] 4) Place the foam nickel loaded with ZIF-67 / Mn(BDC) obtained in step 3) into a tube furnace for pyrolysis reaction, and carbonize the internal organic matter of the ZIF-67 / Mn(BDC) electrocatalytic material loaded on the foam nickel. After heating to 800°C at a rate of 5°C / min and holding for 3 h, the protective atmosphere is Ar, and after cooling to room temperature, the foam nickel loaded with C@Mn-Co-MOF material is obtained.

[0074] 5) Take 1 g of sodium hypophosphite particles and place in boat 1, and place the foam nickel loaded with C@Mn-Co-MOF material obtained in step 4) into boat 2. Boat 1 is placed near the gas inlet of the tube furnace, and boat 2 is placed near the gas outlet. Ar is introduced as a protective gas, and heating is carried out at a rate of 2°C / min to 350°C, holding for 2 h, and then cooling to room temperature to obtain a P@C@Mn-Co-MOF / NF electrocatalyst.

[0075] The scanning diagrams of the structures at each stage obtained in Example 1 are shown in Figure 1 It can be seen that the products prepared at each stage have a good porous structure, and ZIF67 can be uniformly grown on the surface of the sheet-shaped Mn-BDC-MOF structure, improving the electrocatalytic performance of the material.

[0076] The linear voltammetry curve (LSV) of the final electrocatalyst is shown in Figure 4 It can be seen from Figure 4 that at current densities of 10, 100 and 200 mA·cm -2 , the OER reaction overpotential of the P@C@Mn-Co-MOF / NF electrocatalyst is 317, 423 and 468 mV, respectively; at current densities of 10, 100 and 200 mA·cm -2The HER overpotential of the three groups of P@C@Mn-Co-MOF / NF electrocatalysts at a current density of 200 mA·cm-2 was 133 mV, 225 mV and 257 mV, respectively. In actual production, the smaller the overpotential of the catalytic electrode, the smaller the voltage required to reach a certain current density in actual production, that is, the stronger the catalytic activity of the electrocatalyst. Therefore, the P@C@Mn-Co-MOF / NF electrocatalyst has good bifunctional electrocatalytic performance.

[0077] Example 2: The pyrolysis temperature of step 4) in Example 1 was adjusted to 600, 700 and 900℃, and the rest was the same as Example 1. The final products were named P@C(600)@Mn-Co-MOF / NF, P@C(700)@Mn-Co-MOF / NF and P@C(900)@Mn-Co-MOF / NF, respectively.

[0078] The structure scanning diagram of the final product is shown in Figure 2 It can be found that at a lower temperature, the nanopores formed after the nanosheet is fused can be more clearly seen; and at 900℃, the nanocubic ZIF67 particles seriously agglomerate, and basically form a covering layer on the surface of the nickel foam, which shows that the MOF nanoparticles will exhibit different aggregation phenomena at different temperatures, and the MOF particles are more inclined to form block-shaped materials during the high-temperature process. At a lower temperature, the nanosheet can connect the nanoparticles to form a porous network structure.

[0079] In the LSV test, the HER / OER overpotential of the three groups of electrocatalysts in Example 2 at a current density of 200 mA·cm-2 was higher, which showed that 800℃ was still the best pyrolysis temperature at present. -2

[0080] Comparative Example 1: The process of step 3) in Example 1 was skipped, and the rest of the conditions remained unchanged; that is, the foam nickel loaded with Mn-BDC-MOF precursor obtained in step 2) of Example 1 was directly put into a tubular furnace for pyrolysis reaction, and the rest was the same as Example 1.

[0081] The final product was named P@C@Mn-MOF / NF.

[0082] Comparative Example 2: The process of step 2) in Example 1 was skipped, and the rest of the conditions remained unchanged; that is, the "foam nickel loaded with Mn-BDC-MOF precursor obtained in step 2)" in step 3) of Example 1 was changed to "cleaned foam nickel obtained in step 1)"; and the rest was the same as Example 1.

[0083] The final product was named P@C@CoMOF / NF.

[0084] ​Comparative Example 3: Steps 2) and 3) in Example 1 were combined to perform a one-step hydrothermal method, with the following adjustments:

[0085] 0.198 g of MnCl2·4H2O and 0.166 g of terephthalic acid were weighed out, and the two powders were dissolved in 10 mL of N,N-dimethylformamide (DMF), respectively, to obtain two solutions, which were then mixed in a 50 mL polytetrafluoroethylene reaction kettle, 2 mL of a 0.4 M NaOH solution was added, and stirring was performed for 5 min; the resulting mixture was named mixture one;

[0086] 0.291 g of Co(NO3)2·6H2O and 0.3283 g of 2-methylimidazole were weighed out, and the two powders were respectively added to 10 mL of a mixed solvent composed of methanol and ethanol = 1:1 (by volume), and stirring was performed to obtain two solutions, which were then poured into a 50 mL beaker and stirred for 5 min; the resulting mixture was named mixture two;

[0087] The mixture one and mixture two were mixed, stirred for 5 min, and then placed in a cleaned foam nickel in an oven at 100℃ for 15 h, and the reaction product was taken out after cooling, ultrasonic treatment was performed with anhydrous ethanol and deionized water for 5 min, and drying was performed in a vacuum oven at 80℃ for 7 h to obtain a one-step hydrothermal product. The final product was named P@C@MnCo-MOF / NF.

[0088] Figure 3 The structure scanning diagrams of Comparative Example 1, Comparative Example 2 and Comparative Example 3 show that the three materials P@C@Mn-MOF / NF, P@C@Co-MOF / NF and P@C@MnCo-MOF / NF after the same heat treatment process (carbonization and phosphatization process) have obvious agglomeration phenomenon, and the active material mainly exists in the form of a block, which is more unfavorable for the exposure of active sites and the contact of electrolyte with the active material compared with a porous structure, reduces the effective electrochemical active area, and is not conducive to the electrocatalytic performance, which can be seen from the LSV test results in Figure 4 .

[0089] In summary, the MOF material grown on the nanosheet layer MOF structure (MOF ON MOF structure) is successfully prepared through reasonable step-by-step experimental design.

[0090] Table 1, 10 mA cm -2 Comparison of catalytic activity performance of electrocatalysts synthesized under current density

[0091]

[0092] In conclusion, the electric catalyst obtained by the formula corresponding to Embodiment 1 has a good porous structure (according to the SEM image), and the electric catalytic electrode prepared on the basis of the electric catalyst has good catalytic activity. The application has the beneficial effect that another kind of transition metal MOF particles is grown on the transition metal MOF structure by means of high-temperature pyrolysis and phosphorization, and a high specific surface area phosphorized carbon composite porous electric catalyst is obtained through heat treatment. The electric catalyst obtained based on the application has excellent electric catalytic activity in terms of HER / OER.

[0093] Finally, it should also be noted that the above enumeration is only several specific embodiments of the present application. Obviously, the present application is not limited to the above embodiments, but can also have many variations. All variations that can be directly derived or inferred by those of ordinary skill in the art from the content disclosed by the present application should be considered as falling within the protection scope of the present application.

Claims

1. A method for the preparation of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by electrolysis of water, characterized by The method comprises the following steps: 1) cleaning and drying the nickel foam to obtain cleaned nickel foam; 2) synthesis of nanosheet MOF: MnCl2.4H2O is used as a reaction precursor A1, and terephthalic acid is used as an organic ligand A2; The weight ratio of the reaction precursor A1 to the organic ligand A2 is set to 1.1-1.3:1; The reaction precursor A1 and the organic ligand A2 are respectively dissolved in an organic solvent I, so as to respectively obtain a reaction precursor A1 solution and an organic ligand A2 solution; In a reaction kettle, the reaction precursor A1 solution, the organic ligand A2 solution, and a NaOH solution are uniformly stirred and mixed, and then the cleaned nickel foam obtained in step 1) is added, and hydrothermal reaction is performed at 100±10 ℃ for 15±1 h; after being cooled to room temperature, the nickel foam after reaction is taken out, cleaned and dried, and a nickel foam loaded with a Mn-BDC-MOF precursor is obtained; 3) synthesis of a composite multi-dimensional doped MOF: Co(NO3)2.6H2O is used as a reaction precursor B1, and 2-methylimidazole is used as an organic ligand B2; The weight ratio of the reaction precursor A1 to the transition metal reaction precursor B1 is set to 0.6-0.8:1, and the weight ratio of the reaction precursor B1 to the organic ligand B2 is set to 0.8-1:1; The transition metal reaction precursor B1 and the organic ligand B2 are respectively dissolved in an organic mixed solvent, so as to respectively obtain a transition metal reaction precursor B1 solution and an organic ligand B2 solution; In a container, the transition metal reaction precursor B1 solution and the organic ligand B2 solution are uniformly stirred and mixed, and then the nickel foam loaded with the Mn-BDC-MOF precursor obtained in step 2) is added; after being placed at room temperature for 24±2 h, the nickel foam is taken out, cleaned and dried, and a nickel foam loaded with a multi-dimensional doped MOF is obtained; 4) pyrolysis and carbonization: Under the protection of an inert gas, the nickel foam loaded with the multi-dimensional doped MOF obtained in step 3) is subjected to pyrolysis reaction, and after being heated to 600-900 ℃ and kept for 3±0.5 h, the nickel foam loaded with a MOF-derived carbon-based catalyst material is obtained after being cooled to room temperature; 5) phosphating reaction: Sodium hypophosphite particles are placed in a porcelain boat C1, and the nickel foam loaded with the MOF-derived carbon-based catalyst material obtained in step 4) is placed in a porcelain boat C2; the porcelain boat C1 is placed near the gas inlet of a tube furnace, and the porcelain boat C2 is placed near the gas outlet; an inert gas is introduced as a protective gas, and the temperature is increased to 300-450 ℃ at a rate of 2 ℃ / min; after being kept for 2±0.5 h and being cooled to room temperature, a phosphated electrocatalyst is obtained.

2. The process for the preparation of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by electrolysis of water as claimed in claim 1, wherein In step 2): 0.15-0.25 g of MnCl2.4H2O is dissolved in 10 mL of an organic solvent I, so as to obtain a reaction precursor A1 solution; the volume of the organic solvent I used for preparing the organic ligand A2 solution is equal to the volume of the organic solvent I used for preparing the reaction precursor A1 solution; The molar concentration of the NaOH solution is 0.35-0.45 M; The volume ratio of the reaction precursor A1 solution to the NaOH solution is 10:1.5-3.

5.

3. The process for the preparation of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by electrolysis of water as claimed in claim 2, wherein In step 2): The organic solvent I is N,N-dimethylformamide.

4. The method for preparing MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by water electrolysis according to any one of claims 1-3, characterized in that The step 3) is: the organic mixed solvent is a mixture of methanol and ethanol in equal volume.

5. The method for the preparation of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by water electrolysis as claimed in claim 4, wherein The step 3) is: 0.25-0.35 g of Co (NO3) 2·6H2O is dissolved in 10 mL of the organic mixed solvent to obtain a transition metal reaction precursor B1 solution; The volume of the organic mixed solvent used for preparing the organic ligand B2 solution is equal to that used for preparing the transition metal reaction precursor B1 solution.

6. The method for the preparation of MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by electrolysis of water as claimed in claim 5, wherein The step 5) is: The foam nickel with MOF-derived carbon-based catalyst material prepared by each piece of 2 cm x 3 cm foam nickel is prepared with 0.9-1.1 g of sodium hypophosphite.

7. The preparation method of the MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by water electrolysis according to claim 6, characterized in that: The cleaning and drying of the step 2) is: ultrasonic cleaning with anhydrous ethanol and deionized water, and drying in a vacuum oven at 80±10℃ for 5±1h; The cleaning and drying of the step 3) is: cleaning with anhydrous ethanol and deionized water, and drying in a vacuum oven at 80±10℃ for 7±1h.

8. The preparation method of the MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by water electrolysis according to claim 7, characterized in that: The heating rate of step 4) is 5±0.5℃ / min.

9. The preparation method of the MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by water electrolysis according to claim 8, characterized in that: Step 1) involves cutting the nickel foam into 2×3cm pieces. 2 The rectangle was placed in 3M hydrochloric acid and sonicated for 30±5 min, then ultrasonically cleaned with anhydrous ethanol and deionized water respectively, and dried in a vacuum oven at 80±10℃ for 1±0.2 h.

10. The preparation method of the MOF-on-MOF multi-dimensional metal organic framework material for hydrogen production by water electrolysis according to claim 9, characterized in that: The weight ratio of the reaction precursor A1 to the organic ligand A2 is set to 1.2:1; The weight ratio of the reaction precursor A1 to the transition metal reaction precursor B1 is set to 0.68:1, and the weight ratio of the reaction precursor B1 to the organic ligand B2 is set to 0.89:1; The pyrolysis temperature is 800℃.

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