1. Granular CuCo-MOF/MoS₂The preparation method of the catalyst is characterized by comprising the following steps:

(1) measuring N, N-Dimethylformamide (DMF) in a beaker, then measuring ethylene glycol and adding the ethylene glycol, dissolving copper chloride, cobalt acetate and terephthalic acid in the solution, magnetically stirring at room temperature, putting the mixed solution in a high-temperature hydrothermal kettle, heating to 160 ℃ for reaction, cooling the sample to room temperature, repeatedly washing with ethanol and DMF, and centrifugally drying with a centrifuge to obtain CuCo-MOF;

(2) measuring thioacetamide in a beaker, measuring ammonium molybdate in the beaker, adding deionized water in the beaker to dissolve the thioacetamide, baking the thioacetamide in an oven, cooling the thioacetamide to room temperature, repeatedly washing the thioacetamide with the deionized water, and drying the thioacetamide in the oven at 60 ℃ to obtain MoS₂；

(3) Mixing the CuCo-MOF prepared in the step (1) and the MoS prepared in the step (2)₂Mechanically grinding according to the proportion until the materials are uniformly mixed to obtain CuCo-MOF/MoS₂And (3) sampling.

2. The particulate CuCo-MOF/MoS of claim 1₂The preparation method of the catalyst is characterized in that the molar ratio of the copper chloride to the cobalt acetate in the step (1) is 3:1, and the molar ratio of the total mole number of the copper chloride and the cobalt acetate to the mole number of the terephthalic acid is 4: 1-0.8: 1; the magnetic stirring time is 30-50 min; reacting for 9-18 h at 160 ℃.

3. The particulate CuCo-MOF/MoS of claim 1₂The preparation method of the catalyst is characterized in that the molar ratio of thioacetamide to ammonium molybdate in the step (2) is 28: 1-14: 1; reacting for 24 hours at 160-200 ℃ in a reaction kettle.

4. The particulate CuCo-MOF/MoS of claim 1₂The preparation method of the catalyst is characterized in that the CuCo-MOF and MoS in the step (3)₂Is 40: 2-40: 10.

5. a particulate CuCo-MOF/MoS prepared according to the method of any one of claims 1 to 3₂A catalyst.

6. A particulate CuCo-MOF/MoS prepared according to the method of any one of claims 1 to 3₂Use of a catalyst, characterized in that the catalyst is used as a catalyst for Oxygen Evolution (OER) reactions.

Background

The relation between energy and the environment is a big problem which puzzles human life all the time, the traditional energy has great harm to the environment, and the new energy is mostly limited by natural conditions. The electrolyzed water is not only environment-friendly, but also not limited by natural conditions. It is known that the electrolysis of water can be divided into two steps, one being the Hydrogen Evolution Reaction (HER) and the other being the Oxygen Evolution Reaction (OER). The rate of this reaction is mainly determined by the reaction speed of the OER. However, the OER process requires a large amount of energy and has a problem of low energy conversion rate. To solve this problem, the potential barrier in the reaction is first lowered to accelerate the electron transfer rate. The catalyst can effectively promote the reaction, and the main catalysts at present are Pt/C and IrO₂And the like. These noble metals have excellent OER catalytic activity, but they are expensive and scarce in reserves. The non-noble metal catalyst has easily obtained raw materials and abundant reserves, and is suitable for commercial development. The development of cheap and easily available non-noble metal catalysts is imperative.

The catalyst has the problem that active sites are easily embedded in the material. This problem can result in a large number of active sites not participating in the reaction, which in turn affects the catalytic performance of the material. It is important to construct a reasonable structure to provide a material with a larger surface area during the synthesis of the material. The MOF builds an ordered topological structure through an organic bridge and a metal center, so that metal ions can be fully dispersed among organic frameworks, and the utilization rate of active sites is increased. This microstructure is effective in dispersing the active centers, but nanoscale sheet MOFs are prone to stacking. At the same time, too tight a frame results in the interior of the catalyst being difficult to contact with the reaction solution.

Disclosure of Invention

The present invention is based on the background sectionThe deficiency is to provide a granular CuCo-MOF/MoS₂A catalyst, a preparation method and application thereof. The invention adds MoS₂The MOFs can stay on the electrode for a longer time, so that the stability of the material is enhanced. Furthermore, MoS₂The defects of (2) have higher chemical adsorption capacity to hydrogen, and the OER reaction rate can be improved. The addition of high valence Mo ions reduces the potential energy of the reaction, and is beneficial to the generation of oxygen evolution reaction. MoS₂The composite material obtained after grinding together with the MOF reacts more sensitively to changes in voltage.

The invention relates to CuCo-MOF/MoS₂The preparation method comprises the following specific steps:

(1) measuring N, N-Dimethylformamide (DMF) in a beaker, then measuring ethylene glycol and adding the ethylene glycol, dissolving copper chloride, cobalt acetate and terephthalic acid in the solution, magnetically stirring at room temperature, putting the mixed solution in a high-temperature hydrothermal kettle, heating to 160 ℃, and heating for 9-18 h. After cooling the sample to room temperature, it was washed repeatedly with ethanol and DMF and dried by centrifugation several times.

Wherein the molar ratio of the copper chloride to the cobalt acetate is 3:1, and the molar ratio of the total mole number of the copper chloride and the cobalt acetate to the mole number of the terephthalic acid is 4: 1-0.8: 1.

The magnetic stirring time is 30-50 min.

(2) Measuring thioacetamide in a beaker, measuring ammonium molybdate in the beaker, adding deionized water in the beaker to dissolve the thioacetamide, and baking the thioacetamide in an oven. After cooling to room temperature, repeatedly washing with deionized water, and then placing in an oven for drying at 60 ℃.

Wherein the molar ratio of thioacetamide to ammonium molybdate is 28: 1-14: 1.

Reacting for 24 hours in a high-temperature reaction kettle at the temperature of 160-200 ℃.

(3) Mixing the prepared CuCo-MOF with different amounts of MoS₂Mechanically grinding according to the proportion until the materials are uniformly mixed to obtain CuCo-MOF/MoS₂And (3) sampling.

Wherein CuCo-MOF and MoS₂The mass ratio of (A) to (B) is 40: 2-40: 10.

The catalyst prepared by the above method is used as a catalyst for Oxygen Evolution (OER) reaction.

Has the advantages that:

the invention adopts a hydrothermal method to obtain a bimetallic MOF precursor, and then the bimetallic MOF precursor and MoS are mixed₂The sample is obtained by mixing and grinding, and the preparation method of the material is simple, safe and pollution-free.

The product prepared by the invention is nano-scale, and MoS is added into metal organic framework Materials (MOFs)₂The large-batch agglomeration of MOFs is effectively reduced, and meanwhile, the effective contact area of reactants is increased due to the increase of the distance between the flaky MOFs. And by adding MoS₂The MOFs can stay on the electrode for a longer time, so that the stability of the material is enhanced. Furthermore, MoS₂The method has higher chemical adsorption capacity to hydrogen, and improves the rate of OER reaction. The addition of high valence Mo ions reduces the potential energy of the reaction, and is beneficial to the generation of oxygen evolution reaction. MoS₂The composite material obtained after grinding together with the MOF reacts more sensitively to changes in voltage.

Drawings

FIG. 1 shows MoS in example 1₂XRD pattern of (a).

FIG. 2 is the CuCo-MOF/MoS of example 1₂Linear scan LSV plot of catalyst.

FIG. 3 is the composite CuCo-MOF/MoS with the best ratio in example 2₂Electron micrograph of catalyst.

Fig. 4 is a graph of the linear scan LSV of the composites in example 1 and comparative examples 2-4.

Detailed Description

The invention is further illustrated by the following specific examples, which are intended to be illustrative of the invention and are not intended to be a further limitation of the invention.

Example 1

Granular CuCo-MOF/MoS₂The preparation of the catalyst comprises the following steps:

(1) measuring 64mL of N, N-Dimethylformamide (DMF) in a 250mL beaker, measuring 40mL of ethylene glycol, adding 0.1mmol of copper chloride, 0.3mmol of cobalt acetate and 0.2mmol of terephthalic acid into the solution, magnetically stirring the solution at room temperature for 30min, putting the mixed solution in a high-temperature hydrothermal kettle, heating the mixed solution to 160 ℃, and heating the mixed solution for 9 h. After the sample is cooled to room temperature, the sample is repeatedly washed by ethanol and DMF and is dried by centrifuging for a plurality of times by a centrifuge (the centrifugal washing is carried out until no obvious layering phenomenon exists in a clear liquid).

(2) 1.4mmol of thioacetamide is measured in a 100mL beaker, 0.1mmol of ammonium molybdate is measured and added, then 40mL of deionized water is added for dissolution, and the mixture is placed in an oven at 180 ℃ for baking for 24 hours. Cooling to room temperature, repeatedly washing with deionized water (washing with deionized water till no obvious organic solvent layering phenomenon exists in clear liquid), and drying in an oven at 60 deg.C.

(3) Mixing the prepared 40mg MOF and 5mg MoS₂Mechanically grinding until the mixture is uniformly mixed to obtain CuCo-MOF/MoS₂And (3) sampling.

FIG. 1 shows the MoS prepared₂Since the MOFs prepared herein do not have a stable crystalline form, this was not analyzed for crystalline form for the time being. MoS₂Three distinct peaks can be seen in the XRD pattern of (a) which are 14.17 °, 32.91 ° and 58.95 °, respectively. The crystal planes corresponding to these peaks are (002), (100) and (006) from PDF # 75-1539. The above data may demonstrate the successful preparation of product MoS by this text₂。

Example 1 step (1) to produce CuCo-MOF, step (2) to produce MoS₂CuCo-MOF/MoS prepared in step (3)₂The overpotential of (1) is 340mV, and the Cdl is 0.19mF cm^-2，1.46mF cm^-2，23.50mF cm^-2. Substituting the obtained product into a formula to obtain ECSA value, MoS, of various materials₂Has a minimum active area of only 47.5cm²(ii) a Secondly, a single CuCo-MOF value of 365.0cm²(ii) a The best performing is MoS₂CuCo-MOF, up to 587.5cm². It is speculated that more active sites may participate in the reaction as the sulfide blocks the aggregation between the MOF groups and the MOF groups between MOFs.

Weighing 50mg of CuCo-MOF/MoS₂Adding into a 2mL sampling tube, adding 960 μ L distilled water and 40 μ L Nifion, shaking, and performing ultrasonic treatment for 30min to obtain CuCo-MOF/MoS₂And (3) dispersing the mixture.7mL of dispersion liquid is transferred and dripped on a working electrode, and the CuCo-MOF/MoS is prepared by drying under an infrared lamp₂And modifying the electrode.

The electrolyte was 0.1M KOH and pre-energized for 30min N before testing₂To exclude other gases from affecting the results of the experiment. And finally, the working electrode is arranged on ATA-1B (Jiangsu Jiangdi electroanalytical instruments, Inc.) type equipment for LSV test. The scanning speed during the test was 5mV/s and the rotational speed was 1600rpm (FIG. 2). After the test is completed, the measurement potential vs. sce is converted into a reversible hydrogen electrode according to the nernst equation: ERHE ═ 0.241V +0.059 × pH + E measured. Before preparing the working electrode, the RDE is continuously polished to a mirror surface by using 0.3 and 0.05 mu m alumina powder respectively, and then is subjected to ultrasonic treatment in ethanol and deionized water for several times alternately.

Example 2

Steps (1) to (2) were the same as in example 1.

(3) Mixing the prepared 40mg MOF and 2mg MoS₂Mechanically grinding until the mixture is uniformly mixed to obtain CuCo-MOF/MoS₂The sample was subjected to electrochemical LSV testing at an overpotential of 350 mV.

FIG. 3 is an SEM image of the resulting composite material, from which CuCo-MOF/MoS can be seen₂Forms a plurality of fine and broken flakes wrapped on the surface of the small particles. By the method of inclusion of sulfide fragments between MOFs, waste of active area caused by massive accumulation between granular MOFs is prevented, and the purpose of increasing the contact area with a reaction solution is achieved.

The preparation and detection methods of the modified electrode are the same as those of example 1.

Example 3

Steps (1) to (2) were the same as in example 1.

(3) Mixing 40mg MOF and 10mg MoS₂Mechanically grinding until the mixture is uniformly mixed to obtain CuCo-MOF/MoS₂The sample was subjected to electrochemical LSV testing at an overpotential of 420 mV.

Example 4

The molar ratio of the total mole number of the copper chloride and the cobalt acetate to the terephthalic acid in the step (1) is 4:1, and the rest is the same as that in the example 1 to obtain the copper chloride-cobalt acetate copolymerTo CuCo-MOF/MoS₂The sample was subjected to electrochemical LSV testing at an overpotential of 440 mV.

Example 5

The molar ratio of the total mole number of the copper chloride and the cobalt acetate to the terephthalic acid in the step (1) is 4:3, and the other steps are the same as those in the example 1 to obtain CuCo-MOF/MoS₂The sample was subjected to electrochemical LSV testing at an overpotential of 360 mV.

Example 6

The molar ratio of the total mole number of the copper chloride and the cobalt acetate to the terephthalic acid in the step (1) is 1:1, and the other steps are the same as those in the example 1 to obtain CuCo-MOF/MoS₂The sample was subjected to electrochemical LSV testing at an overpotential of 350 mV.

Example 7

The molar ratio of the total mole number of the copper chloride and the cobalt acetate to the terephthalic acid in the step (1) is 4:5, and the other steps are the same as those in the example 1 to obtain CuCo-MOF/MoS₂The sample was subjected to electrochemical LSV testing at an overpotential of 400 mV.

Example 8

The molar ratio of thioacetamide to ammonium molybdate in the step (2) is 28:1, and the other steps are the same as those in the example 1 to obtain CuCo-MOF/MoS₂The sample was subjected to electrochemical LSV testing at an overpotential of 373 mV.

Comparative example 1

The CuCo-MOF preparation method is the same as that in the step (1) of the example 1, and the CuCo-MOF and sulfur are mechanically ground and mixed according to the mixing ratio of 40:5 and the current density of 10mA cm^-2Under the condition of (1), the overpotential is 460mV and the Cdl is 14.48mF cm^-2Substituting the obtained value into a formula to obtain the ECSA value of the material, 362cm². The performance is far inferior to that of MoS₂/CuCo-MOF。

Comparative example 2

Referring to example 1, step (1), Cu-MOF was prepared by mixing 40mg of Cu-MOF with 5mg of MoS₂Mechanically grinding and mixing to obtain the composite material catalyst with the current density of 10mAcm^-2Under the condition (2), the LSV curve has no intersection point. It cdl is 0.36mF cm^-2The ECSA value of the material is obtained by substituting the formula, 9cm². The performance is not good.

Comparative example 3

Referring to example 1, step (1), Co-MOF was prepared by mixing 40mg of Co-MOF with 5mg of MoS₂Mechanically grinding and mixing to obtain the composite material catalyst with the current density of 10mA cm^-2Under the condition of (1), the overpotential is 417mV and the Cdl is 10.74mF cm^-2The ECSA value of the material is obtained by substituting the formula, 268cm²。

Comparative example 4

The preparation method is the same as the steps (1) and (2) of the example 1, the step (3) is compounded and changed into direct hydrothermal method (30 ml DMF is measured, 20ml deionized water is put into a beaker, and 40mg of CuCo-MOF and MoS are weighed₂Adding 5mg of the mixture into the mixed solvent, stirring uniformly, carrying out ultrasonic treatment for 30min, transferring the mixture into a reaction kettle, reacting for 3h at 120 ℃, washing the mixture by using deionized water and ethanol until no obvious layering exists, and drying the mixture to obtain a sample. ) At a current density of 10mAcm^-2Under the condition (1), the overpotential is tested to be 470 mV.

FIG. 4 is a plot of the LSV of the linear scan of comparative examples 1-4 and best performing samples.