MOF (Metal Organic Framework) material for negative carbon hydrogen production as well as preparation and application methods of MOF material

Abstract

The invention belongs to the field of metal organic framework materials, and particularly relates to a negative carbon hydrogen production MOF material and a preparation and application method thereof. The molecular formula of the single crystal structure of the MOF material is [Co (SMN) n], M is diiy or bitp, when M is diiy, the molecular formula can be written as [Co (diiy) (SCN)], and when M is bitp, the molecular formula can be written as [Co (bitp) (SCN) 2]; wherein the diiy is 2, 6-bis (1H-imidazole-1-yl)-pyridine, and the bitp is 2, 6-bis (1H-1, 2, 4-triazole-1-yl)-pyridine. According to the invention, by adjusting the structure of the ligand, two catalytic materials for producing hydrogen by negative carbon under photocatalysis are prepared. CO2 is used as a raw material to participate in a reaction to generate hydrogen; the method has huge application potential in the fields of environmental protection, clean energy production, green chemical industry and the like.

Description

Technical Field

[0001] The present invention belongs to the field of metal organic framework materials, and specifically relates to a MOF material for negative carbon hydrogen production and a preparation and application method thereof. Background Art

[0002] Photocatalytic hydrogen production is a technology that uses solar energy to decompose water to produce hydrogen. It is considered a sustainable way to produce clean energy. Photocatalytic hydrogen production technology relies on specific materials to decompose water to produce hydrogen under light conditions. These materials usually have semiconductor properties that can absorb photons and generate electron-hole pairs, which in turn drive redox reactions. The core of this technology lies in the photocatalyst, which can absorb light energy and trigger the cracking reaction of water molecules to produce hydrogen and oxygen. The design and optimization of photocatalysts are the key to improving the efficiency of photocatalytic hydrogen production.

[0003] In recent years, researchers have made a series of progress in the field of photocatalytic hydrogen production. For example, the Lu Gang team at Nanjing Tech University has developed an efficient and stable photocatalytic system that significantly improves the reaction efficiency by using the plasma effect. In addition, the Guo Feng and Shi Weilong teams at Jiangsu University of Science and Technology have constructed an S-type heterojunction that utilizes the full spectrum to promote photothermal-assisted photocatalytic hydrogen production. This structure achieves excellent charge carrier dynamics and significantly improves the photocatalytic activity.

[0004] In terms of material design, researchers have improved the performance of photocatalysts by constructing heterogeneous structures, regulating crystal phases, introducing defects, etc. For example, the research team of Tianjin University of Technology and Tianjin University effectively adjusted the physical and chemical properties of materials through crystal phase engineering, especially the construction of heterogeneous structures, providing a new way to develop high-performance photocatalysts.

[0005] The development of photocatalytic hydrogen production technology requires not only the progress of materials science, but also a deep understanding of the photocatalytic mechanism. For example, in an article published in Nature Communications, Sui Manling's research group at Beijing University of Technology successfully introduced optical fibers into a liquid environment transmission electron microscope to observe the photocatalytic water splitting hydrogen production process in situ, revealing that TiO 2 The key role of the surface hydrogenation layer in the photocatalytic process.

[0006] Negative carbon hydrogen production means that while producing hydrogen, carbon dioxide can be effectively fixed and restricted. This technology not only helps reduce the concentration of carbon dioxide in the atmosphere, but also provides a clean energy carrier - hydrogen. Negative carbon hydrogen production technology represents an important direction for the development of clean energy in the future. It not only provides clean hydrogen, but also achieves net removal of carbon dioxide during the production process.

[0007] The main challenges facing photocatalytic hydrogen production technology include:

[0008] 1. Stability of photocatalysts: Traditional photocatalysts may experience performance degradation during long-term operation, affecting their stability and economy.

[0009] 2. Light absorption efficiency: Many photocatalysts have insufficient absorption of the solar spectrum, especially in the visible light region, which limits the effective use of light energy.

[0010] 3. Carrier recombination rate: The rapid recombination of photogenerated electrons and holes reduces the photocatalytic efficiency, so an effective mechanism is needed to separate and transport these carriers.

[0011] 4. Photocatalyst activity: Improving the activity of photocatalysts, especially without the assistance of precious metals, is the key to improving the efficiency of photocatalytic hydrogen production.

[0012] 5. Low-energy production: Developing low-cost, environmentally friendly production methods to produce photocatalyst materials is an important step in achieving commercial applications.

[0013] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0014] To meet the above challenges, the present invention has prepared two materials with high catalytic activity for negative carbon hydrogen production by adjusting the ligands. They have good thermal stability, catalytic activity, low production cost and low pollution, and can solve some of the challenges faced by current photocatalytic hydrogen production technology. The materials prepared by this method can be used as catalysts to not only produce hydrogen, but also absorb and fix carbon dioxide.

[0015] The above technical objectives of the present invention are achieved through the following technical solutions:

[0016] A MOF material for negative carbon hydrogen production, wherein the molecular formula of the single crystal structure of the MOF material is [Co(M)(SCN)n], wherein M is diiy or bitp, when M is diiy, n is 1, and the molecular formula can be written as [Co(diiy)(SCN)], denoted as diiy-Co, when M is bitp, n is 2, and the molecular formula can be written as [Co(bitp)(SCN) 2 ], denoted as bitp-Co;

[0017] Wherein, the diiy is 2,6-bis-(1H-imidazol-1-yl)-pyridine, and the bitp is 2,6-bis(1H-1,2,4-triazol-1-yl)-pyridine.

[0018] Specifically, when M is diiy, n is 1, and when M is bitp, n is 2. This is due to the difference in their ligands. The diiy ligand contains imidazole, and the bitp ligand contains triazole, which leads to differences in their coordination environment. Therefore, the coordinated coordination with SCN- is also different. The MOF of the present invention uses the coordinated design of ligands (diiy / bitp) and SCN- to convert CO 2 The capture, activation and H 2 The efficient dissociation of O is integrated into the same catalytic system. Its negative carbon hydrogen production mechanism includes the following key steps:

[0019] (1) MOF pore structure selectively adsorbs CO 2 and H 2 O;

[0020] (2) Separation of electron-hole pairs under light / electric excitation;

[0021] (3) Directed electron transfer to CO 2 and H + ;

[0022] (4) Hole consumption maintains the catalytic cycle.

[0023] Preferably, when the molecular formula is [Co(diiy)(SCN)], the MOF material belongs to the monoclinic system, the P21 / n space group, and the unit cell parameters are The bond angle of N-Co-N ranges from 87.59(6) to 180.00(12).

[0024] Preferably, the minimum asymmetric unit of the material consists of a metal Co ion, a SCN- and a ligand diiy; the coordination mode is an octahedral structure, in which the bond length of the N-Co bond is between 0.93 and 2.1746 (17); the diiy ligand and the Co atom extend in two directions through coordination to form a two-dimensional network structure.

[0025] As a preferred embodiment, when the molecular formula is [Co(bitp)(SCN) 2 ], the MOF material belongs to the orthorhombic system, Cmca space group, and the unit cell parameters are The bond angle of N-Co-N ranges from 86.32(5) to 178.95(9).

[0026] Preferably, the minimum asymmetric unit of the material consists of a metal Co ion, two SCN- and a ligand bitp; the coordination mode is an octahedral structure, in which the bond length of the N-Co bond is 0.95 to 2.1642 (15); and a one-dimensional chain structure extending in one direction and in a lattice shape is formed by extension.

[0027] The second aspect of the present invention is to provide a method for preparing the above-mentioned negative carbon hydrogen production material with high catalytic activity, which has the same technical effect. The above-mentioned technical purpose of the present invention is achieved through the following technical solutions:

[0028] A method for preparing a MOF material for negative carbon hydrogen production, the method comprising:

[0029] S1. Preparation of organic ligand diiy:

[0030] Place a mixture of cuprous iodide, cesium carbonate, imidazole and 2,6-dibromopyridine in a round-bottom flask and stir at room temperature for 30-40 minutes, raise the temperature to 125°C-135°C and continue the reaction for 24-28 hours, cool to room temperature after the reaction is completed, add dichloromethane, extract and collect with water, concentrate under reduced pressure, and dry to obtain the product;

[0031] S2. Preparation of organic ligand bitp:

[0032] Dissolve 1,2,4-triazole and potassium tert-butoxide in DMSO, stir for 15-20 minutes until the reaction is complete, and cool to room temperature. Add 2,6-dibromopyridine to the mixture, heat and reflux at 135-145°C for 24-28 hours, cool to room temperature, add water, cool and filter, wash and dry;

[0033] S3. Preparation of complex:

[0034] An aqueous solution of cobalt chloride, a mixed solution of methanol and water, and a methanol solution of a ligand and potassium thiocyanate are prepared, and the three solutions are placed in a test tube from top to bottom in order of density from large to small, and the tube is sealed and allowed to stand for 20 to 30 days to obtain a crystalline complex suitable for single crystal X-ray diffraction testing.

[0035] Specifically, when the ligand is diiy, the mixture is sealed and allowed to stand for about 20 days to obtain a complex with light pink crystals suitable for single crystal X-ray diffraction testing. When the ligand is bitp, the mixture is sealed and allowed to stand for about 30 days to obtain a complex with pink crystals suitable for single crystal X-ray diffraction testing.

[0036] Preferably, in step S1, the molar ratio of cuprous iodide, cesium carbonate, imidazole and 2,6-dibromopyridine is 1:12-20:12-15:3-5, and the volume ratio of dichloromethane and water is 1:2-6.

[0037] Preferably, in step S2, the molar ratio of 1,2,4-triazole, potassium tert-butoxide and 2,6-dibromopyridine is 1:0.15-0.45:0.24-0.62.

[0038] Preferably, in step S3, when the ligand diiy is used, the volume ratio of the cobalt chloride aqueous solution, the mixed solution of methanol and water, and the ligand to the methanol solution of potassium thiocyanate is 1:1~2:1~4; when the ligand bitp is used, the volume ratio of the cobalt chloride aqueous solution, the mixed solution of methanol and water, the ligand to the methanol solution of potassium thiocyanate is 1:0.5~1:1~2.

[0039] The third aspect of the present invention provides two applications of negative carbon hydrogen production materials with high catalytic activity.

[0040] The MOF material can be used as a photocatalyst in the fields of energy storage, environmental purification, and industrial hydrogen production. Hydrogen has attracted much attention as a new energy-intensive chemical and an ideal fuel. The traditional steam reforming hydrogen production method does not meet the requirements of sustainable development due to its high carbon emissions. 2 Capture and utilization, achieving H 2 Production and CO 2 Fixed, providing new solutions for sustainable development.

[0041] Compared with the prior art, this application has the following beneficial effects:

[0042] Negative carbon hydrogen production catalytic materials have shown great application potential in the fields of environmental protection, clean energy production and green chemical industry due to their unique advantages. 2 Capture and H 2 Production provides an innovative technical path to achieve sustainable development goals. Future research will further optimize the performance of these materials, expand their application range, and promote the commercialization of related technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 (a) is the topological structure diagram of diiy-Co. Figure 1 (b) is the topological structure diagram of bitp-Co;

[0045] Figure 2 Infrared spectra of diiy-Co and bitp-Co;

[0046] Figure 3 (a) is the PXRD pattern of diiy-Co. Figure 3 (b) is the PXRD pattern of bitp-Co;

[0047] Figure 4 (a) is the thermogravimetric analysis diagram of diiy-Co. Figure 4 (b) is the thermogravimetric analysis diagram of bitp-Co;

[0048] Figure 5 (a) is the UV absorption spectra of diiy-Co and bitp-Co. Figure 5 (b) Tauc plot of diiy-Co and bitp-Co;

[0049] Figure 6 Impedance diagram of diiy-Co and bitp-Co;

[0050] Figure 7 (a) Mott-Shottky plot of diiy-Co, Figure 7 (b) is the Mott-Shottky plot of bitp-Co;

[0051] Figure 8 (a) Parallel experiment of diiy-Co photocatalysis, Figure 8 (b) Parallel photocatalytic experiment of bitp-Co;

[0052] Fig. 9 (a) is the photocatalytic spot sampling experiment of bitp-Co. Fig. 9 (b) is the diiy-Co photocatalytic spot sampling experiment;

[0053] Fig.10 Schematic diagram of the front-line tracks of diiy-Co and bitp-Co. DETAILED DESCRIPTION

[0054] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, a MOF material for producing hydrogen with negative carbon and its preparation and application method proposed in the present invention, its specific implementation method, characteristics and effects are described in detail as follows. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0055] All chemical reagents used in the experiment were purchased from merchants without purification. They were from manufacturers such as Anage Chemical and Shanghai Lingfeng Pharmaceutical Group. Details are shown in Table 1; experimental instruments and models are shown in Table 2.

[0056] Table 1

[0057] Reagents Specification Manufacturer 2,6-Dibromopyridine Analytical grade Bid Pharmaceuticals Potassium tert-butoxide Analytical grade ANEJI CHEMICALS Imidazole Analytical grade ANEJI CHEMICALS 1,2,4-Triazole Analytical grade ANEJI CHEMICALS Cuprous iodide Analytical grade Shanghai MacLean Biopharmaceutical Technology Co., Ltd. Cesium carbonate Analytical grade ANEJI CHEMICALS Cobalt chloride Chemically pure Anhui Zesheng Technology Co., Ltd. Sodium sulfate Analytical grade Shanghai Lingfeng Pharmaceutical Group Potassium thiocyanate Analytical grade Sinopharm Group Dichloromethane Analytical grade Sinopharm Group Dimethyl sulfoxide Analytical grade Sinopharm Group Deionized water Analytical grade Laboratory procurement

[0058] Table 2

[0059]

[0060]

[0061] Example 1

[0062] The present invention proposes a MOF material for negative carbon hydrogen production, wherein the molecular formula of the single crystal structure of the MOF material is [Co(M)(SCN)n], wherein M is diiy or bitp, when M is diiy, n is 1, and the molecular formula can be written as [Co(diiy)(SCN)], when M is bitp, n is 2, and the molecular formula can be written as [Co(bitp)(SCN) 2 ];

[0063] Wherein, the diiy is 2,6-bis-(1H-imidazol-1-yl)-pyridine, and the bitp is 2,6-bis(1H-1,2,4-triazol-1-yl)-pyridine.

[0064] The prepared crystals were collected under a microscope and the crystallographic data of the complexes were acquired on a Bruker APEX-IICCD instrument equipped with graphene monochromatic radiation Mo Kα The data were collected at the corresponding temperature. The data collection, data reduction and unit optimization were performed using two program packages, BrukerInstrument Service v4.2.2 and SAINT V8.34A. The structure of the complex was solved using the SHELXS program package, and the crystal data were optimized using the full matrix least squares method using the SHELXL program package. Absorption correction was performed using the multi-scan program package SADABS. The hydrogen atoms of the organic ligands were detected by riding mode on the F 2 The crystallographic data of the complex are shown in Table 3. The bond lengths of some of the complexes are The data of bond angle (°) are shown in Table 4.

[0065] Table 3

[0066]

[0067]

[0068] a R 1 =Σ(||F 0 |-|F c ||) / Σ|F 0 |; b wxya 2 =[Σw(|F 0 2 |-|F c2 |) 2 / Σw|F 0 2 | 2 ] 1 / 2 ; c GOF=[∑[w(F 0 2 -F c 2 ) 2 ] / (N obs -N params )] 1 / 2 , based on the data I>2σ(I).

[0069] Table 4

[0070]

[0071]

[0072]

[0073] Specifically, the smallest asymmetric unit of diiy-Co is composed of a thiocyanate, a metal cobalt atom and a ligand. Figure 1 (b) The structure of the material is a two-dimensional network structure. The diiy ligands and the metal cobalt atoms extend in two directions through coordination to form a two-dimensional structure. The smallest asymmetric unit of bitp-Co is composed of two thiocyanates, metal cobalt atoms and ligands. Its structure is a regular one-dimensional chain structure. The bitp ligands and the metal cobalt atoms form a structure that extends in one direction to form a lattice structure. In addition, Figure 1 The topological diagram in (b) can more intuitively show the regular one-dimensional chain arrangement.

[0074] Example 2

[0075] Preparation of organic ligand diiy: A mixture of cuprous iodide (1.04 mmol, 0.198 g), cesium carbonate (16.6 mmol, 5.4088 g), imidazole (12.6 mmol, 0.858 g) and 2,6-dibromopyridine (4.2 mmol, 0.9948 g) was placed in a round-bottom flask, stirred at room temperature for 30 minutes, raised the temperature to 130°C and continued to react for 24 hours, and cooled to room temperature after the reaction was completed. 60 ml of dichloromethane was added, and the mixture was extracted and collected with 60 ml of water, concentrated under reduced pressure, and dried over sodium sulfate to obtain the product.

[0076] Example 3

[0077] Preparation of complex [Co(diiy)(SCN) 2]: Prepare an aqueous solution (2 ml) of cobalt chloride (0.02 mmol, 0.0048 g), a 1:1 mixed solution of methanol and water (1.5 ml), and a methanol solution (2 ml) of the ligand diiy (0.02 mmol, 0.0040 g) and potassium thiocyanate (0.04 mmol, 0.0038 g). Place the three solutions in a test tube from top to bottom in order of density from large to small. Seal the tube and let it stand for about 20 days to obtain a complex with light pink crystals suitable for single crystal X-ray diffraction test. The yield is 70%.

[0078] Example 4

[0079] Preparation of organic ligand BITp: 1,2,4-triazole (9.72mmol, 0.671g) and potassium tert-butoxide (3.04mmol, 1.090g) were dissolved in (4-6ml) DMSO, stirred for a period of time until the reaction was complete, and cooled to room temperature. 2,6-dibromopyridine (4.22mmol, 1.001g) was added to the mixture, heated to reflux at 140℃ for 24h, cooled to room temperature to produce yellow to brown oil, 50ml of water was added to obtain a white suspension, the mixture was placed in an ice bath for 1h, cooled and filtered, and vacuum dried.

[0080] Example 5

[0081] Preparation of the complex [Co(bitp)(SCN) 2 ]: Prepare an aqueous solution (2.5 ml) of cobalt chloride (0.1 mmol, 0.0238 g), 0.5 ml of a solution of a 1:1 mixture of methanol and water, and a methanol solution (2.5 ml) of the ligand BITp (0.1 mmol, 0.0213 g) and potassium thiocyanate (0.2 mmol, 0.0194 g). Place the three solutions in a test tube from top to bottom in order of density from large to small. Seal the tube and let it stand for about 30 days to obtain a pink crystal complex suitable for single crystal X-ray diffraction test with a yield of 75%.

[0082] Performance Testing

[0083] (1) Infrared test

[0084] like Figure 2 As shown, at 4000~400cm -1 Infrared was measured in the range of 1600-1500cm -1 The difference in the peaks is due to the different C=N stretching vibrations of diiy-Co and bitp-Co. -1 At , the characteristic peaks of thiocyanate can be observed in both diiy-Co and bitp-Co.

[0085] (2) Thermogravimetric test

[0086] At 25~800℃, N 2 In the atmosphere, the temperature is raised at a rate of 10°C / min, and the change in sample mass with temperature is recorded. At the end of the experiment, a TG curve is drawn, such as Figure 4 The thermal behavior of the samples was shown and analyzed.

[0087] The collapse of diiy-Co is divided into two steps. First, it starts to collapse at 293℃, and the ligand decomposition occurs first. Then, the framework collapses at 485℃~800℃, causing the original structure to completely collapse. The collapse of bitp-Co begins with the decomposition of the ligand at 273℃. This process is different from that of diiy-Co, and it also involves the gradual destruction of the forces between nitrogen atoms, and the complete collapse ends at 445℃. In comparison, diiy-Co has better thermal stability.

[0088] (3) Crystal powder diffraction:

[0089] The XRD experimental values ​​were recorded on a RINT-2000 vertical goniometer with Cu Kα (40KV, 100mA) as the radiation source. The single crystal cif file was opened in Crystal Diffract and the PXRD pattern shown in the figure was obtained by calculation and simulation. Figure 3 As shown, it can be seen that the diffraction peaks of diiy-Co and bitp-Co are basically consistent with the simulated peaks of single crystal diffraction, which proves that the crystal purity is good.

[0090] (4) Electrochemical test

[0091] The three-electrode system was used for testing, with Ag / AgCl electrode as reference electrode, Pt electrode as counter electrode, and glassy carbon electrode as working electrode. Before the test, nitrogen was introduced into the electrolyte of 0.1M sodium sulfate solution for 30 minutes to remove oxygen in the electrolyte. In addition, 5 mg of catalyst was added to a centrifuge tube, and a mixed solution of 150 μL ethanol, 75 μL deionized water, and 25 μL Nafion was added. A uniform catalyst ink was prepared by ultrasonic treatment for 15 minutes, and then immersed on a glassy carbon electrode with a diameter of 0.4 cm, and dried under ultraviolet light to complete the electrode preparation process.

[0092] The impedance of the catalyst was measured on an electrochemical workstation. Figure 6 As shown in the figure, the impedance of bitp-Co is an arc, and the impedance of diiy-Co is an inclined straight line. This shows that bitp-Co is controlled by the charge transfer process, diiy-Co is controlled by the diffusion process, the bitp charge transfer rate is faster, and the catalytic effect is better.

[0093] The Mott-Schottky properties of the catalyst were measured at frequencies of 1000 Hz, 1500 Hz, and 2000 Hz. Figure 7As shown, the flat band potential of diiy-Co is -0.91eV, from which the conduction band potential of diiy-Co is -0.69eV; the flat band potential of bitp-Co is -1.36eV, from which the conduction band potential of bitp-Co is -1.14eV; Fig.10 As shown, under standard conditions, the electrochemical reaction potential difference of water reduction to hydrogen is -0.41 V, and the test potential is more negative than this potential, indicating the feasibility of the catalyst in kinetically catalyzing hydrogen production.

[0094] (5) Solid UV test:

[0095] We used a UV-visible spectrophotometer to collect the reflected light from the sample surface through an integrating sphere and projected it onto the electrical signal generated by the detector to obtain the spectral curves of diiy-Co and bitp-Co, as shown in Figure 5 As shown. The absorbance of diiy is slightly higher than that of bitp, and the overall UV absorption peaks are similar. The band gap of diiy-Co is 3.40eV and the band gap of bitp-Co is 3.27eV by Tauc plot method. In comparison, the band gap of bitp-Co is narrower, and the theoretical catalytic effect is better, which is consistent with the actual situation.

[0096] (6) Photocatalytic test

[0097] A 105W xenon lamp and a 400nm filter were used to simulate sunlight. A catalytic tube was placed in a glass container filled with deionized water and irradiated under the xenon lamp. The photocatalytic products after irradiation were detected by gas chromatography. Figure 7 As shown, three parallel experiments were performed. Figure 8 As shown in Figure 2, the hydrogen yield of diiy-Co was 4.52 mmol g under 5 h of illumination. -1 h -1 The hydrogen yield of bitp-Co was 5.77 mmol g -1 h -1 In order to further explore the catalytic effect of the catalyst, we conducted a 6-h spot sampling experiment on diiy-Co and bitp-Co. Fig. 9 As shown, it was found that the hydrogen production of the catalyst reached a peak at 4h, and no longer increased significantly in the following time. According to the experiment, the hydrogen production of diiy-Co reached 15.8868mmol / g in 4h, and the hydrogen production of bitp-Co reached 29.2734mmol / g in 4h, a difference of 1.84 times. This is caused by the difference in ligand structure. The nitrogen atom on the bitp ligand forms a lone electron pair, which plays an important role in promoting the separation of photogenerated electrons and holes. It can accelerate the migration of electrons from the inside of the catalyst to the surface, reducing the probability of electron-hole recombination, thereby producing a better catalytic effect.

[0098] In summary, bitp-Co has a narrower band gap and better catalytic hydrogen production effect, while diiy-Co has better thermal stability, as shown in Table 5.

[0099] Table 5

[0100] catalyst Yield Hydrogen production Conduction band potential Band Gap Thermal decomposition temperature diiy-Co <![CDATA[4.52mmol g -1 h -1 ]]> 15.8868mmol / g -0.69eV 3.40eV 293℃ bitp-Co <![CDATA[5.77mmol g -1 h -1 ]]> 29.2734mmol / g -1.14eV 3.27eV 273℃

[0101] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A MOF material for negative carbon hydrogen production, characterized in that: The molecular formula of the single crystal structure of the MOF material is [Co(M)(SCN)n], wherein M is diiy or bitp. When M is diiy, n is 1, and the molecular formula can be written as [Co(diiy)(SCN)]; when M is bitp, n is 2, and the molecular formula can be written as [Co(bitp)(SCN)2]; Wherein, the diiy is 2,6-bis-(1H-imidazol-1-yl)-pyridine, and the bitp is 2,6-bis(1H-1,2,4-triazol-1-yl)-pyridine.

2. A MOF material for negative carbon hydrogen production according to claim 1, characterized in that: When the molecular formula is [Co(diiy)(SCN)], the MOF material belongs to the monoclinic system, the P21 / n space group, and the unit cell parameters are a = 11.1042(9) Å, b =9.2227(8) Å, c = 12.8305(10) Å, and the N-Co-N bond angle ranges from 87.59(6) to 180.00(12).

3. A MOF material for negative carbon hydrogen production according to claim 2, characterized in that: The smallest asymmetric unit of the material consists of a metal Co ion, a SCN- and a ligand diiy; the coordination mode is an octahedral structure; the bond length of the N-Co bond is 0.93~2.1746(17); the diiy ligand and the Co atom extend in two directions through coordination to form a two-dimensional network structure.

4. The MOF material for negative carbon hydrogen production according to claim 1, characterized in that: When the molecular formula is [Co(bitp)(SCN)2], the MOF material belongs to the orthorhombic system, Cmca space group, and the unit cell parameters are a = 17.0452(4) Å, b =19.9935(6) Å, c = 14.6178(4) Å, and the N-Co-N bond angle ranges from 86.32(5) to 178.95(9).

5. A MOF material for negative carbon hydrogen production according to claim 4, characterized in that: The smallest asymmetric unit of the material consists of a metal Co ion, two SCN- and a ligand bitp; the coordination mode is an octahedral structure, in which the bond length of the N-Co bond is 0.95~2.1642(15); and a one-dimensional chain structure extending in one direction and in a lattice shape is formed by extension.

6. The method for preparing a MOF material for negative carbon hydrogen production according to any one of claims 1 to 5, characterized in that: The method includes: S1. Preparation of organic ligand diiy: A mixture of cuprous iodide, cesium carbonate, imidazole and 2,6-dibromopyridine is placed in a round-bottom flask, stirred at room temperature, and the temperature is raised to continue the reaction. After the reaction is completed, the mixture is cooled to room temperature, dichloromethane is added, and the mixture is extracted and collected with water, concentrated under reduced pressure, and dried to obtain the product; S2. Preparation of organic ligand bitp: Dissolve 1,2,4-triazole and potassium tert-butoxide in DMSO, stir for a while until the reaction is complete, and cool to room temperature. Add 2,6-dibromopyridine to the mixture, heat to reflux, cool to room temperature, add water, cool, filter, wash and dry; S3. Preparation of complex: An aqueous solution of cobalt chloride, a mixed solution of methanol and water, and a methanol solution of the ligand and potassium thiocyanate were prepared, and the three solutions were placed in a test tube from top to bottom in order of density from large to small. The tube was sealed and allowed to stand for 20 to 30 days to obtain a crystalline complex suitable for single crystal X-ray diffraction testing.

7. The method for preparing a MOF material for negative carbon hydrogen production according to claim 6, characterized in that: In step S1, the molar ratio of cuprous iodide, cesium carbonate, imidazole and 2,6-dibromopyridine is 1:12-20:12-15:3-5, and the volume ratio of dichloromethane and water is 1:2-6.

8. The method for preparing a MOF material for negative carbon hydrogen production according to claim 6, characterized in that: In step S2, the molar ratio of 1,2,4-triazole, potassium tert-butoxide and 2,6-dibromopyridine is 1:0.15-0.45:0.24-0.

62.

9. The method for preparing a MOF material for negative carbon hydrogen production according to claim 6, characterized in that: In step S3, when the ligand diiy is used, the volume ratio of the cobalt chloride aqueous solution, the mixed solution of methanol and water, the ligand and the methanol solution of potassium thiocyanate is 1:1~2:1~4; when the ligand bitp is used, the volume ratio of the cobalt chloride aqueous solution, the mixed solution of methanol and water, the ligand and the methanol solution of potassium thiocyanate is 1:0.5~1:1~2.

10. The application method of the MOF material for negative carbon hydrogen production according to any one of claims 1 to 5, characterized in that: The MOF material can be used as a photocatalyst in the fields of energy storage, environmental purification, and industrial hydrogen production.

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