A MoSOx / COF-C4N composite catalyst, its preparation method and application

Abstract

The present invention provides a MoSO x / COF-C4N composite catalyst and its preparation method and application, belonging to the technical field of catalyst preparation. The MoSO x is distributed on the COF-C4N; the mass ratio of the MoSO x to the COF-C4N is 1 to 4:1 to 4; the MoSO x is synthesized by hydrothermal method from L-cysteine and sodium molybdate; the COF-C4N is prepared from triphenylene-2,3,6,7,10,11-hexamine hexahydrochloride, hexaketocyclohexane octahydrate, an organic solvent and a reaction environment regulator. By introducing the composite of oxygen-deficient MoSO x and COF-C4N, the present invention realizes electrocatalytic hydrogen evolution, oxygen evolution and electrocatalytic overall water splitting at all pH values.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and particularly to a MoSO x / COF-C4N composite catalyst, its preparation method and application. Background Art

[0002] The extensive use of fossil fuels has polluted the environment and affected people's health. Therefore, energy reform and the research and development of new energy are urgent problems to be solved today. As a renewable and efficient new energy, hydrogen energy has the highest calorific value and the most environmentally friendly combustion products, and has great research value today when environmental pollution is becoming increasingly severe. Among them, electrocatalytic water splitting for hydrogen production is the most environmentally friendly and efficient method among various hydrogen production methods. Studying non-noble metal catalysts that can improve the efficiency of electrolytic water and have low costs is of great significance for the development of new energy.

[0003] Covalent organic frameworks (COFs) are crystalline solids composed of organic monomers connected by strong covalent bonds. They are porous framework materials with advantages such as large specific surface area, low framework density, strong stability, programmable structure, and high carrier transport rate. The framework structure and crystal characteristics similar to those of nanocarbon materials of COFs can carry sufficient active sites and precisely control their coordination environment with the active sites. And COF-C4N has been studied to have the ability of electrocatalytic water splitting for oxygen production under alkaline conditions. Molybdenum disulfide (MoS2), as the most typical transition metal sulfide, has become a promising material in the catalytic field because of its structural properties similar to those of graphite and its more excellent energy band structure than graphite. However, its poor conductivity and limited active sites limit its catalytic performance. Summary of the Invention

[0004] To solve the above problems, the present invention provides a MoSO x / COF-C4N composite catalyst, its preparation method and application. By combining MoSO x with oxygen vacancies with COF-C4N, the present invention realizes electrocatalytic hydrogen evolution, oxygen evolution and electrocatalytic overall water splitting at all pH values.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a MoSO x / COF-C4N composite catalyst, which is obtained by distributing MoSO x on COF-C4N;

[0007] The mass ratio of the MoSO x to COF-C4N is 1 to 4:1 to 4;

[0008] The MoSO x is synthesized by hydrothermal method from L-cysteine and sodium molybdate;

[0009] The COF-C4N is prepared from triphenylene-2,3,6,7,10,11-hexamine hexahydrochloride, hexaketocyclohexane octahydrate, organic solvent and reaction environment regulator.

[0010] Preferably, the mass ratio of the MoSO x to COF-C4N is 2-3:2-3.

[0011] Preferably, the mass ratio of the MoSO x to COF-C4N is 2:1.

[0012] Preferably, the mass ratio of the L-cysteine to sodium molybdate is 303:103.

[0013] The present invention also provides a preparation method of the MoSO x / COF-C4N composite catalyst described in the above technical solution, comprising the following steps:

[0014] 1) Mix the triphenylene-2,3,6,7,10,11-hexamine hexahydrochloride, hexaketocyclohexane octahydrate and organic solvent, and perform ultrasonic treatment to obtain an ultrasonic product;

[0015] Mix the ultrasonic product with the reaction environment regulator to obtain a dispersion;

[0016] After degassing the dispersion, react at 150 °C for 72 h to obtain a crude reaction product;

[0017] Wash the crude reaction product with tetrahydrofuran to obtain a brownish-black solid, and perform Soxhlet extraction of the brownish-black solid with tetrahydrofuran until the effluent liquid is colorless, and then stop to obtain a solid product;

[0018] Dry the solid product at 100 °C for 24 h to obtain COF-C4N;

[0019] 2) Mix the L-cysteine, sodium molybdate and water, and then perform ultrasonic treatment and stirring in sequence to obtain a dispersion;

[0020] React the dispersion at 200 °C for 24 h, and dry the obtained solid at 100 °C for 12 h to obtain MoSO x ;

[0021] 3) Grind the COF-C4N obtained in step 1) and the MoSO x obtained in step 2), disperse them in an ethanol solution, perform ultrasonic treatment, stirring, and suction filtration to obtain a filter cake;

[0022] Dry the filter cake at 90 °C for 30 min to obtain MoSO x / COF-C4N composite catalyst.

[0023] Preferably, the grinding time in step 3) is 10 min, the ultrasonic time is 2 h, and the stirring time is 36 h; the temperatures of grinding, ultrasonic treatment, and stirring are all 0 °C.

[0024] Preferably, the conditions of ultrasonic treatment in step 1) include: temperature 25 °C, time 30 min; the ultrasonic treatment time in step 2) is 30 min.

[0025] The present invention also provides the application of the MoSO x / COF-C4N composite catalyst in electrocatalytic hydrogen evolution.

[0026] The present invention also provides the application of the MoSO x / COF-C4N composite catalyst in electrocatalytic oxygen evolution.

[0027] The present invention also provides the application of the MoSO x / COF-C4N composite catalyst in electrocatalytic overall water splitting.

[0028] The beneficial effects of the present invention are as follows:

[0029] (1) The method of the present invention is simple, efficient, easy to operate, and has practical application significance.

[0030] (2) By introducing oxygen vacancies into MoS2 through a simple hydrothermal method to generate MoSO x , the catalytic performance of MoS2 is greatly improved.

[0031] (3) By grinding, ultrasonic treatment, and stirring under low-temperature conditions, MoSO x and COF-C4N are directly compounded, which simultaneously improves the electrocatalytic oxygen evolution performance of COF-C4N and the electrocatalytic hydrogen evolution ability of MoSO x , and the stability of sulfide is greatly improved after compounding. The materials obtained by this method have excellent electrocatalytic hydrogen evolution, oxygen evolution, and overall water splitting performance.

[0032] (4) Through the wet chemical synthesis method of grinding, ultrasonic treatment, and stirring, the multi-layer structure of COF-C4N and MoSO x is changed into a few-layer or single-layer structure, and a heterojunction is formed by van der Waals force binding. The low-temperature conditions also well preserve MoSO xThe 1T phase prevents the disappearance of oxygen vacancies. Due to its ultrathin lamellar structure, the material exposes more active sites and has a larger specific surface area. The porous structure of COF-C4N also greatly improves the electron transport efficiency in the heterojunction, thus obtaining a full water splitting material with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments.

[0034] Figure 1 X-ray powder diffraction patterns of COF-C4N, MoSO x and MoSO x / COF-C4N composite catalyst.

[0035] Figure 2 Infrared spectra of COF-C4N, MoSO x and MoSO x / COF-C4N composite catalyst.

[0036] Figure 3 Raman spectra of MoSO x and MoSO x / COF-C4N composite catalyst.

[0037] Figure 4 X-ray photoelectron spectra of MoSO x / COF-C4N composite catalyst, where (a) is the XPS survey spectrum, and (b)-(f) are the XPS spectra of each element.

[0038] Figure 5 Transmission electron microscopy images, scanning electron microscopy images and elemental mapping images of MoSO x / COF-C4N composite catalyst, where (a)-(c) are the transmission electron microscopy images of the composite catalyst at different magnifications, (d)-(e) are the transmission electron microscopy images of the composite catalyst at different magnifications, and (f) is the elemental mapping image of different elements.

[0039] Figure 6 Linear sweep voltammograms of MoSO x / COF-C4N composite catalyst for electrocatalytic hydrogen evolution.

[0040] Figure 7 Linear sweep voltammograms of MoSO x / COF-C4N composite catalyst for electrocatalytic oxygen evolution.

[0041] Figure 8 In the case of MoSO xLinear sweep voltammetry curves of the MoSO

[0042] Figure 9 / COF-C4N composite catalyst for overall water splitting in electrolytes with different pH values;

[0043] Figure 10 Results of oxygen evolution stability test;

[0044] Figure 11 Results of hydrogen evolution stability test;

[0045] Figure 12 Results of LSV of OER for materials with different ratios;

[0046] Figure 13 Results of LSV of HER for materials with different ratios;

[0047] Figure 14 EIS diagram of OER of the composite catalyst in Example 1;

[0048] Figure 15 EIS diagram of HER of the composite catalyst in Example 1. Detailed implementation mode

[0049] The present invention provides a MoSO x / COF-C4N composite catalyst, which is obtained by distributing MoSO x on COF-C4N; the mass ratio of MoSO x to COF-C4N is 1-4:1-4; the MoSO x is synthesized by hydrothermal method from L-cysteine and sodium molybdate; the COF-C4N is prepared from triphenylene-2,3,6,7,10,11-hexamine hexahydrochloride, hexaketocyclohexane octahydrate, organic solvent and reaction environment regulator. In the present invention, the mass ratio of L-cysteine to sodium molybdate is preferably 303:103. In the present invention, the mass ratio of MoSO x to COF-C4N is 1-4:1-4, preferably 2-3:2-3, and more preferably 2:1.

[0050] In the present invention, the organic solvent preferably includes 1,4-dioxane and 1,3,5-trimethylbenzene, and the volume ratio of 1,4-dioxane to 1,3,5-trimethylbenzene is preferably 1:1. In the present invention, the reaction environment regulator preferably includes acetic acid solution, and the molar concentration of the acetic acid solution is preferably 4 mol / L. In the present invention, the mass ratio of triphenylene-2,3,6,7,10,11-hexamine hexahydrochloride, cyclohexanehexone octahydrate, the volume of the organic solvent, and the volume of the reaction environment regulator is preferably 25.5 mg:25 mg:3 mL:0.5 mL.

[0051] The present invention also provides a preparation method of the MoSO x / COF-C4N composite catalyst according to the above technical solution, comprising the following steps:

[0052] 1) Mix and ultrasonicate the triphenylene-2,3,6,7,10,11-hexamine hexahydrochloride, cyclohexanehexone octahydrate, and the organic solvent to obtain an ultrasonicated product;

[0053] Mix the ultrasonicated product with the reaction environment regulator to obtain a dispersion;

[0054] Degas the dispersion and react at 150 °C for 72 h to obtain a crude reaction product;

[0055] Wash the crude reaction product with tetrahydrofuran to obtain a brownish-black solid, and subject the brownish-black solid to Soxhlet extraction with tetrahydrofuran until the effluent liquid is colorless, and then stop to obtain a solid product;

[0056] Dry the solid product at 100 °C for 24 h to obtain COF-C4N;

[0057] 2) Mix L-cysteine, sodium molybdate, and water, and then perform ultrasonic treatment and stirring in sequence to obtain a dispersion;

[0058] React the dispersion at 200 °C for 24 h, and dry the obtained solid at 100 °C for 12 h to obtain MoSO x ;

[0059] 3) Grind the COF-C4N obtained in step 1) and the MoSO x obtained in step 2), disperse them in an ethanol solution, ultrasonicate, stir, and filter to obtain a filter cake;

[0060] Dry the filter cake at 90 °C for 30 min to obtain the MoSO x / COF-C4N composite catalyst.

[0061] In the present invention, the triphenylene-2,3,6,7,10,11-hexamine hexahydrochloride and hexaketocyclohexane octahydrate are preferably ground and then mixed with an organic solvent. In the present invention, the conditions for the ultrasonic treatment in step 1) preferably include: a temperature of 25 °C, a time of 30 min, and a power of 200 W. In the present invention, the degassing preferably includes: purging with nitrogen - evacuating, and then using freezing - thawing for degassing, and this operation is repeated three times.

[0062] In the present invention, the time for the ultrasonic treatment in step 2) is preferably 30 min. The present invention preferably performs stirring at room temperature, and the time for the stirring is preferably 60 min.

[0063] In the present invention, the volume ratio of ethanol to water in the ethanol solution is 4:6. In the present invention, the COF-C4N and MoSO x Dispersion in the ethanol solution is preferably carried out by ultrasonic treatment. The time for the ultrasonic treatment is 2 h, the ultrasonic temperature does not exceed 10 °C, and after ultrasonic treatment, stirring is carried out at room temperature for 36 h.

[0064] The present invention grinds the obtained COF-C4N and the obtained MoSO x Grinds, disperses in an ethanol solution, ultrasonic treatment, stirring, and suction filtration to obtain a filter cake. In the present invention, the time for the grinding is preferably 10 min, the time for the ultrasonic treatment is preferably 2 h, the power of the ultrasonic treatment is 200 W, the time for the stirring is preferably 36 h; the temperatures for the grinding, ultrasonic treatment, and stirring are all preferably 0 °C.

[0065] In the present invention, the water is preferably distilled water.

[0066] The present invention also provides the application of the above-mentioned MoSO x / COF-C4N composite catalyst in electrocatalytic hydrogen evolution.

[0067] The present invention also provides the application of the above-mentioned MoSO x / COF-C4N composite catalyst in electrocatalytic oxygen evolution.

[0068] The present invention also provides the application of the above-mentioned MoSO x / COF-C4N composite catalyst in electrocatalytic overall water splitting.

[0069] To further illustrate the present invention, the present invention will be described in detail below with reference to examples, but they should not be construed as limiting the protection scope of the present invention.

[0070] Example 1

[0071] MoSO xPreparation method of / COF-C4N catalyst material, the steps are as follows:

[0072] (1) Preparation of COF-C4N

[0073] At room temperature, 25.5 mg of triphenylene-2,3,6,7,10,11-hexamine hexahydrochloride (CAS No.: 1159202-33-1) and 25 mg of hexaketocyclohexane octahydrate are sufficiently ground, and the mixture is added to a mixed organic solvent solution of 1.5 mL of 1,4-dioxane and 1.5 mL of 1,3,5-trimethylbenzene. It is ultrasonically treated at 25 °C for 30 min, and then 0.5 mL of 4 mol / L acetic acid solution is added to obtain a dispersion;

[0074] After purging nitrogen and evacuating the dispersion, degassing is carried out using freezing and thawing, and this operation is repeated three times; the degassed dispersion is placed in an oven at 150 °C for reaction for 72 h. After the oven temperature drops to room temperature, the test tube is taken out to obtain a crude reaction product; the crude reaction product is filtered and washed with tetrahydrofuran, and after natural drying, a brownish-black solid product is obtained; the solid product is subjected to Soxhlet extraction with tetrahydrofuran until the effluent liquid is colorless; the obtained solid product is vacuum dried at 100 °C for 24 h to obtain a two-dimensional covalent organic framework material (COF-C4N) with a crystal structure;

[0075] (2) Preparation of MoSO x

[0076] At room temperature, 302.88 mg of L-cysteine and 103 mg of sodium molybdate are added to 60 mL of distilled water and ultrasonically treated for 30 min, and stirred at room temperature for 60 min to uniformly disperse the ligand. Subsequently, the dispersion is placed in an oven at 200 °C for reaction for 24 h. After the oven temperature drops to room temperature, the reaction kettle is taken out to obtain a crude reaction product; the crude product is filtered and washed with a large amount of distilled water, and the obtained solid product is vacuum dried at 100 °C for 12 h to obtain pure MoSO x .

[0077] (3) Wet synthesis of MoSO x / COF-C4N composite catalyst

[0078] Weigh 20 mg and 40 mg of the products in steps (1) and (2) respectively, grind them at 0 °C for 10 min and then disperse them in a mixed solution of water and ethanol and ultrasonically treat for 2 h. The volume ratio of water to ethanol in the mixed solution is 6:4. Subsequently, the mixed solution is stirred at low temperature (0 °C) for 36 h to form a uniformly dispersed solution. The dispersed solution is filtered by suction, and the filter cake is vacuum dried at 90 °C for 30 min to obtain MoSO x / COF-C4N composite catalyst.​

[0079] The obtained MoSO x / COF-C4N composite catalyst (10 mg), carbon black (10 mg) were added to a mortar. After thorough grinding, they were loaded into a small centrifuge tube. 750 ml of distilled water, 230 ml of ethanol, and 10 ml of 5% naphthol were added to the centrifuge tube to form a dispersion. The dispersion was ultrasonically treated for 1 h to obtain a homogeneous dispersion. 100 μl of the dispersion was evenly coated on a carbon cloth with an area of 1 cm 2 . Using the carbon cloth as the working electrode, the electrocatalytic hydrogen evolution, oxygen evolution, and overall water splitting capabilities of the MoSO x / COF-C4N composite catalyst were measured by the linear voltammetry scanning diagram, as shown in Figure 6 , Figure 7 , Figure 8 . The LSV tests were all carried out in a three-electrode system with a scanning rate of 10 mV / s. The hydrogen evolution test range was 0 V to -1 V, and the solution was 0.5 M H2SO4. The oxygen evolution test voltage range was 0 to 1 V, and the solution was 1 M KOH. The overall water splitting test was a two-electrode system, and the fabricated working electrode was used as the anode and cathode. The solution was a buffer solution with different pH values.

[0080] Stability test, the test method used was chronoamperometry:

[0081] Among them: The oxygen evolution stability test was obtained by applying a voltage of 1.5 V in 1 M KOH solution. The hydrogen evolution stability test was obtained by applying a voltage of -0.65 V in 0.5 M H2SO4. In the overall water splitting stability: the test was carried out at a voltage of 1.58 V when pH = 0 and at a voltage of 1.605 V when pH = 14. The results are shown in Figures 9 - 11 .

[0082] From the stability test diagrams ( Figures 9 - 11 ), it can be seen that: Under the condition of continuous testing for 40 h, the oxygen evolution performance of the material maintained good stability in the alkaline solution. Under the condition of continuous testing for 40 h, the hydrogen evolution performance of the material maintained good stability in the acidic solution. Under the condition of continuous testing for 16 h, the overall water splitting performance of the material maintained good stability.

[0083] Figure 1 are the XRD spectra of COF-C4N, MoSO x and MoSO x / COF-C4N. The diffraction peak of the MoSO x curve at 9.2° proves the successful synthesis of oxygen vacancies in MoSO x . The characteristic diffraction peak at 32.7° corresponds to the (100) crystal plane of MoSO x , which can prove MoSO xThere is an obvious growth preference orientation. MoSO x / COF-C4N shows the (001) crystal plane corresponding to the diffraction peak of COF-C4N at 27°, and MoSO x shows the (100) crystal plane at 32.7°, which proves the successful synthesis of the composite material. It can be seen from the figure that the characteristic peaks of MoSO x and MoSO x / COF-C4N composite are relatively wide and weak in intensity, indicating that the wet preparation method causes lattice distortion and defects in the material. This distortion can be attributed to the electronic reconstruction caused by oxygen vacancies. Due to the existence of oxygen vacancies, the crystallinity gradually decreases, resulting in flat characteristic peaks.

[0084] Figure 2 is the infrared spectrum of MoSO x / COF-C4N material. It can be observed from the figure that the vibration peaks at 3421.84 cm -1 , 2811 cm -1 , 1606 cm -1 , 1458 cm -1 and 1305.7 cm -1 correspond to N-H, C-H, C-C, C=C and CH3 in COF-C4N respectively, and the vibration peaks of COF-C4N and MoSO x are completely retained in the MoSO x / COF-C4N material, proving the successful synthesis of MoSO x / COF-C4N.

[0085] Figure 3 is the Raman spectrum of MoSO x material and MoSO x / COF-C4N. From the Raman spectrum of MoSO x , it can be seen that the typical MoS2 vibration peaks appear at 385.4 cm -1 and 405.9 cm -1 , which are attributed to the in-plane vibration of E 2g and the interlayer vibration of A 1g respectively. In the Raman scan of the 514 nm laser, the MoS2 vibration peaks show a blue shift towards the short-wavelength direction (339.5 cm -1 and 378.1 cm -1 , belonging to the 2H phase), while new vibration peaks appear at 100 - 300 cm -1 (121.6, 150.5, 200.7, 239.2 and 287.4 cm -1), belonging to the 1T phase, these changes are caused by the phase transition of MoS2, indicating the formation of oxygen vacancies and related to the lattice disorder caused by oxygen vacancies. At the same time, peaks at 287.4 cm -1 , 665.1 cm -1 and 823.5 cm -1 and 995.2 cm -1 are attributed to the typical fingerprint vibration modes of MoO x . For the composite MoSO x / COF-C4N sample, the vibration peaks of MoSO x are completely retained and the peak intensities are relatively flat, indicating that the sample is successfully composite, has a good structure and is ultrathin.

[0086] Figure 4 is the X-ray photoelectron spectroscopy pattern of the MoSO x / COF-C4N composite catalyst. Figure 4 The XPS full-spectrum results in (a) show that the material contains five elements: C, N, Mo, S, and O. Figure 4 In (b-c), it is confirmed that COF-C4N in MoSO x / COF-C4N is successfully synthesized. Figure 4 In (e), it shows two spin-orbit coupling peaks of the O element at 533.1 eV and 531.5 eV, belonging to adsorbed oxygen and oxygen vacancies respectively, proving the successful synthesis of oxygen vacancies. And Figure 4 in (f), the characteristic peaks of the Mo element at 231.7 eV and 228.5 eV belong to Mo 3d 5 / 2 and Mo 3d 3 / 2 . The characteristic peaks shift in the direction of decreasing binding energy compared to MoS2 as a whole, proving that the Mo element in MoSO x / COF-C4N gains electrons and undergoes a reduction reaction, which is consistent with the positively charged oxygen vacancies and the enhanced binding energy of oxygen elements, proving the successful introduction of oxygen vacancies. In addition, after the narrow-spectrum fitting and peak separation of the Mo element and S element, it can be seen that MoSO x mostly exists in the 1T phase after composite.

[0087] Figure 5 are the transmission electron microscopy image, scanning electron microscopy image and elemental mapping image of the MoSO x / COF-C4N composite catalyst. From Figure 5 in (a)-(e), it can be clearly seen that the flower-like MoSO xDistributed on the flaky COF-C4N, the material exhibits a thickness close to that of a single layer, with local light transmission and good ductility. This special morphological feature enables the heterojunction material to be in full contact with the solution, maximizing the exposure of the active sites of the material. Elements such as C, N, O, S, and Mo can be seen to be evenly present in the EDS, proving the successful synthesis of the composite material.

[0088] Figure 6 For MoSO x / COF-C4N composite catalyst for electrocatalytic hydrogen evolution linear voltammetry scan. It can be seen that MoSO x / COF-C4N composite catalyst at a current density of -10 mA cm -2 The potential at this point is only 0.65 V.

[0089] Figure 7 For MoSO x / COF-C4N composite catalyst for electrocatalytic oxygen evolution linear voltammetry scan. It can be seen that MoSO x / COF-C4N composite catalyst at a current density of 10 mA cm -2 The potential at this point is 1.48 V.

[0090] Figure 8 For MoSO x / COF-C4N composite catalyst for electrocatalytic overall water splitting at different pH values linear voltammetry scan. The best performance among them is MoSO x / COF-C4N composite catalyst in an electrolyte with a pH value of 0 when the current density is 10 mA cm -2 The potential at this point is 1.58 V.

[0091] In summary, the present invention successfully synthesizes the MoSO x / COF-C4N composite catalyst by a wet method, and the catalyst has ultra-high electrocatalytic hydrogen evolution and oxygen evolution efficiencies and can perform overall water splitting at all pH values.

[0092] By processing the CV curve of the MoSO x / COF-C4N(2:1) material, a function relationship diagram of the current density and scan rate of the composite material is obtained ( Figure 14 and Figure 15 ). It can be seen from the figure that: After calculation, the double-layer capacitance value of the MoSO x / COF-C4N material is 7 mF cm -2 , indicating that it has a relatively large electrochemically active surface area, which is one of the reasons for its high electrocatalytic oxygen evolution / hydrogen evolution activity.

[0093] Example 2

[0094] COF-C4N and MoSO x The mass ratio of COF-C4N to MoSO is 4:1, and the rest is the same as in Example 1. The results are shown in Figures 12 - 13 .

[0095] Example 3

[0096] COF-C4N and MoSO x The mass ratio of COF-C4N to MoSO is 3:1, and the rest is the same as in Example 1. The results are shown in Figures 12 - 13 .

[0097] Example 4

[0098] COF-C4N and MoSO x The mass ratio of COF-C4N to MoSO is 2:1, and the rest is the same as in Example 1. The results are shown in Figures 12 - 13 .

[0099] Example 5

[0100] COF-C4N and MoSO x The mass ratio of COF-C4N to MoSO is 1:1, and the rest is the same as in Example 1. The results are shown in Figures 12 - 13 .

[0101] Example 6

[0102] COF-C4N and MoSO x The mass ratio of COF-C4N to MoSO is 1:3, and the rest is the same as in Example 1. The results are shown in Figures 12 - 13 .

[0103] Example 7

[0104] COF-C4N and MoSO x The mass ratio of COF-C4N to MoSO is 1:4, and the rest is the same as in Example 1. The results are shown in Figures 12 - 13 .

[0105] Oxygen evolution ( Figure 12 ): It can be seen from the figure that the OER performance of M COF-C4N :M MoSOx = 1:1, 1:2, 1:3, 1:4, 2:1, 3:1, 4:1 is shown, and it is confirmed that when M COF-C4N :M MoSOx = 1:2, the OER performance of the composite material is the best at 1.463 V, 1.574 V at 1:1, 1.589 V at 1:3, 1.69 V at 1:4, 1.53 V at 2:1, 1.623 V at 3:1, and 1.695 V at 4:1.

[0106] Hydrogen evolution ( Figure 13 ): It can be seen from the figure that the HER performance of M COF-C4N :M MoSOx = 1:1, 1:2, 1:3, 1:4, 2:1, 3:1, 4:1 is shown, and it is confirmed that when MCOF-C4N : M MoSOx When the ratio is 1:2, the HER performance of the composite material is the best at -0.65V. When it is 1:1, it is -0.73V. When it is 1:3, it is -0.148V. When it is 1:4, it is -0.167V. When it is 2:1, it is -0.96V. When it is 3:1, it is -0.217V.

[0107] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on this embodiment without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A MoSO x / COF-C4N composite catalyst, characterized in that MoSO is synthesized by wet synthesis methods of grinding, ultrasonic treatment, and stirring x and directly compounded with COF-C4N, and MoSO x is obtained by being distributed on COF-C4N; The MoSO x has a mass ratio to COF-C4N of 1 to 4: 1 to 4; The MoSO x has oxygen vacancies and is synthesized by hydrothermal method using L-cysteine and sodium molybdate; the mass ratio of L-cysteine to sodium molybdate is 303:103; The COF-C4N is prepared from triphenylene-2,3,6,7,10,11-hexamine hexahydrochloride, hexaketocyclohexane octahydrate, an organic solvent, and a reaction environment regulator.

2. The MoSO as claimed in claim 1 x / COF-C4N composite catalyst, characterized in that The MoSO x has a mass ratio to COF-C4N of 2 to 3: 2 to 3.

3. The MoSO according to claim 1 x / COF-C4N composite catalyst, characterized in that The MoSO x has a mass ratio of 2:1 with COF-C4N.

4. Preparation method of MoSO x / COF-C4N composite catalyst according to any one of claims 1 to 3, characterized in that, It includes the following steps: 1) Mix triphenylene-2,3,6,7,10,11-hexamine hexahydrochloride, hexaketocyclohexane octahydrate, and an organic solvent, and perform ultrasonic treatment to obtain an ultrasonic product; Mix the ultrasonic product with a reaction environment regulator to obtain a dispersion; After degassing the dispersion, react it at 150 °C for 72 h to obtain a crude reaction product; Wash the crude reaction product with tetrahydrofuran to obtain a brownish-black solid. Perform Soxhlet extraction of the brownish-black solid with tetrahydrofuran until the outflow liquid is colorless, and then stop to obtain a solid product; Dry the solid product at 100 °C for 24 h to obtain COF-C4N; 2) Mix L-cysteine, sodium molybdate, and water, and then perform ultrasonic treatment and stirring in sequence to obtain a dispersion; React the dispersion at 200 °C for 24 h, dry the obtained solid at 100 °C for 12 h to obtain MoSO x ; 3) Mix the COF-C4N obtained in step 1) with the MoSO obtained in step 2) x Grind, disperse in an ethanol solution, sonicate, stir, and filter by suction to obtain a filter cake; Dry the filter cake at 90 °C for 30 min to obtain MoSO x / COF-C4N composite catalyst.

5. The preparation method according to claim 4, wherein, In step 3), the grinding time is 10 min, the ultrasonic time is 2 h, and the stirring time is 36 h; the temperatures of grinding, ultrasonic treatment, and stirring are all 0 °C.

6. The preparation method according to claim 4, characterized in that, The conditions of ultrasonic treatment in step 1) include: temperature 25 °C, time 30 min; the ultrasonic treatment time in step 2) is 30 min.

7. Use of the MoSO x / COF-C4N composite catalyst in electrocatalytic hydrogen evolution.

8. Use of the MoSO x / COF-C4N composite catalyst in electrocatalytic oxygen evolution.

9. Use of the MoSO x / COF-C4N composite catalyst in electrocatalytic overall water splitting.

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