Preparation method of 1t phase molybdenum sulfide and application thereof

Abstract

The application discloses a preparation method of 1T phase molybdenum sulfide and application thereof, and the method comprises the following steps: under the action of an applied magnetic field, taking ammonium molybdate tetrahydrate and thiourea as a molybdenum source and a sulfur source respectively, taking cobalt nitrate hexahydrate as an initiator, and generating 1T phase molybdenum sulfide in a reaction process through a one-step hydrothermal method. The 1T phase molybdenum sulfide is used for preparing an oxygen evolution and hydrogen evolution bifunctional electrode. The application utilizes a magnetic field and Co atoms to convert a hydrothermal synthesis product from 2H phase molybdenum sulfide into 1T phase molybdenum sulfide, and prepares a HER and OER bifunctional catalyst with high conductivity and excellent catalytic performance. The method is simple and economical, the effect is remarkable, the problem of difficulty in preparing 1T phase molybdenum sulfide catalyst is solved, and the method has great application value in the field of electrochemical catalysis.

Description

TECHNICAL FIELD

[0001] The present application relates to the fields of new energy materials and electrocatalysis, and in particular to a preparation method of 1T-phase molybdenum sulfide and application thereof. BACKGROUND

[0002] Hydrogen is a clean energy with high energy density and can be obtained by electrochemical decomposition of water. However, the traditional Pt-based catalysts are low in abundance and high in price, which limits the development of hydrogen production by water electrolysis. The 1T-phase molybdenum sulfide, as a new catalyst for hydrogen production by water electrolysis, solves the problems of the Pt-based catalysts, and is an excellent substitute for the Pt-based catalysts due to high catalytic activity, low cost and high abundance. However, the 1T-phase molybdenum sulfide is a metastable phase, and the synthesis conditions are harsh, and there are still many impurities in the synthesized product, which seriously restricts the development of the 1T-phase molybdenum sulfide in the research of hydrogen production by water electrolysis. Therefore, how to simply synthesize the 1T-phase molybdenum sulfide catalyst has become one of the urgent problems to be solved in the research of hydrogen production by water electrolysis. SUMMARY

[0003] The present application aims to provide a preparation method of 1T-phase molybdenum sulfide and application thereof, which is simple in synthesis process, low in synthesis cost, and has high catalytic activity.

[0004] In one aspect of the present application, a preparation method of 1T-phase molybdenum sulfide is provided. According to the embodiments of the present application, the method comprises the following steps: under the action of an external magnetic field, 1T-phase molybdenum sulfide is generated in a reaction process by a one-step hydrothermal method, with ammonium molybdate tetrahydrate and thiourea as molybdenum source and sulfur source respectively, and cobalt nitrate hexahydrate as an initiator.

[0005] In addition, the preparation method of 1T-phase molybdenum sulfide according to the above embodiments of the present application can further have the following additional technical features:

[0006] In some embodiments of the present application, the external magnetic field is provided by two samarium-cobalt permanent magnets located on the same central axis and having opposite positive and negative poles.

[0007] In some embodiments of the present application, the diameter of the samarium-cobalt permanent magnet is 25-35 mm, the height is 18-20 mm, and the surface magnetic field strength of the samarium-cobalt permanent magnet is 0.35-0.45 T.

[0008] In some embodiments of the present application, the distance between the two samarium-cobalt permanent magnets is 58-62 mm.

[0009] In some embodiments of the present application, the molar ratio of the ammonium molybdate tetrahydrate, the thiourea and the cobalt nitrate hexahydrate is 4:28:1-5.

[0010] In some embodiments of the present application, the concentration of the ammonium molybdate tetrahydrate is 0.010-0.020 mol / L, the concentration of the thiourea is 0.10-0.20 mol / L, and the concentration of the cobalt nitrate hexahydrate is 0.001-0.01 mol / L.

[0011] In some embodiments of the present application, the ammonium molybdate tetrahydrate and the thiourea are stirred for 45-60 min before the cobalt nitrate hexahydrate is added.

[0012] In some embodiments of the present application, the temperature of the hydrothermal method is about 180-220℃, and the time is 18-24 h.

[0013] In some embodiments of the present application, after the 1T phase molybdenum sulfide is obtained, it is washed with deionized water and anhydrous ethanol, and then dried.

[0014] In another aspect of the present application, the present application provides an application of the 1T phase molybdenum sulfide. According to embodiments of the present application, the 1T phase molybdenum sulfide prepared by the preparation method of the 1T phase molybdenum sulfide is used to prepare an oxygen evolution and hydrogen evolution bifunctional electrode.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] (1) The present application adds a new reaction condition, i.e., a magnetic field, to the conventional hydrothermal reaction, so that the product is converted from the 2H phase to the 1T phase.

[0017] (2) The 1T phase conversion rate of the present application is high, and the 1T phase has good stability.

[0018] (3) The 1T phase molybdenum sulfide synthesized by the present application has high catalytic activity, high conductivity, and excellent catalytic performance, and belongs to a HER (electrocatalyst hydrogen evolution reaction) and OER (oxygen evolution reaction) bifunctional catalyst.

[0019] (4) The present application has low material cost, is environmentally friendly, has a simple preparation process, is easy to operate, and has high feasibility. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the XRD diffraction pattern of Example 1 and Comparative Example 1 of the present application:

[0021] Figure 2 is the Raman spectrum of Example 1 and Comparative Example 1 of the present application;

[0022] Figure 3 is the scanning electron microscope photo of the 1T phase molybdenum sulfide of Example 1 of the present application;

[0023] Figure 4 is the XRD diffraction pattern of the 1T phase molybdenum sulfide synthesized in Examples 2-5 of the present application;

[0024] Figure 5 is the HER polarization curve of Example 1 and Comparative Example 1 when 1 mol / L KOH is used as the electrolyte and a three-electrode system is adopted in the application example of the present application;

[0025] Figure 6 is the OER polarization curve of Example 1 and Comparative Example 1 when 1 mol / L KOH is used as the electrolyte and a three-electrode system is adopted in the application example of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0027] Example 1

[0028] A preparation method of 1T phase molybdenum sulfide, comprising the following steps:

[0029] (1) Build an external magnetic field environment, embed a cylindrical high-temperature-resistant samarium-cobalt magnet with a diameter of 30 mm and a height of 20 mm into a polytetrafluoroethylene shell. The polytetrafluoroethylene shell is a cylinder with an outer diameter of 57.2 mm and a height of 30 mm, and has a cylindrical pit with an inner diameter of 30 mm and a depth of 20 mm coaxial with the polytetrafluoroethylene shell at the bottom. There are two polytetrafluoroethylene shells, one with the N-pole of the magnet outside and the other with the S-pole of the magnet outside. The inner lining of the reactor is 54 mm high and 57.2 mm in diameter. Assemble the polytetrafluoroethylene shell, reactor lining, and polytetrafluoroethylene shell in three layers in the form of a reaction kettle shell, and the side of the polytetrafluoroethylene shell containing the magnet is in contact with the reactor lining.

[0030] (2) Configure the reaction precursor: the solvent water is 30 ml, the ammonium molybdate tetrahydrate and thiourea are 0.5 mmol and 3.5 mmol respectively, and 0.25 mmol of cobalt nitrate hexahydrate is added after stirring for 1 hour using a magnetic stirrer and stirring for 40 minutes again.

[0031] (3) Place the reaction precursor in the reactor, assemble it at 200 degrees Celsius and react for 22 hours.

[0032] (4) After the reaction is completed, take out the suspension in the reactor and place it in a centrifuge tube, use a high-speed centrifuge at 6000 r / min for 3 min, then use ethanol and deionized water to wash alternately for 3 times, and finally dry in a vacuum oven at 60 degrees Celsius.

[0033] Figure 1XRD pattern of 1T phase molybdenum disulfide of Example 1. The (002) plane diffraction peak is at 14°, which belongs to 1T phase.

[0034] Figure 2 Raman spectrum of Example 1 and Comparative Example 1. Two diffraction peaks of Comparative Example 1 are at 378 cm -1 and 404 cm -1 , which belongs to 2H phase; while Example 1 appears J1, J2, J3, E 1g diffraction peaks which belong to 1T phase molybdenum sulfide, which indicates that the crystal phase of Example 1 is 1T phase.

[0035] Figure 3 Scanning electron microscope photo of 1T phase molybdenum sulfide of Example 1, which is flower-like nanospheres, and the diameter of single sphere is about 500 nm, and different nanospheres are clustered with each other.

[0036] Example 2

[0037] This example is basically the same as Example 1, the only difference is that in step (2), the ammonium molybdate tetrahydrate and thiourea are 0.5 mmol and 3.5 mmol respectively, and after stirring for 1 hour using a magnetic stirrer, 0.10 mmol of cobalt nitrate hexahydrate is added and stirred for 40 minutes again.

[0038] Example 3

[0039] This example is basically the same as Example 1, the only difference is that in step (2), the ammonium molybdate tetrahydrate and thiourea are 0.5 mmol and 3.5 mmol respectively, and after stirring for 1 hour using a magnetic stirrer, 0.40 mmol of cobalt nitrate hexahydrate is added and stirred for 40 minutes again.

[0040] Example 4

[0041] This example is basically the same as Example 1, the only difference is that in step (2), the ammonium molybdate tetrahydrate and thiourea are 0.5 mmol and 3.5 mmol respectively, and after stirring for 1 hour using a magnetic stirrer, 0.60 mmol of cobalt nitrate hexahydrate is added and stirred for 40 minutes again.

[0042] Example 5

[0043] This example is basically the same as Example 1, the only difference is that in step (2), the ammonium molybdate tetrahydrate and thiourea are 0.5 mmol and 3.5 mmol respectively, and after stirring for 1 hour using a magnetic stirrer, 0.80 mmol of cobalt nitrate hexahydrate is added and stirred for 40 minutes again.

[0044] Figure 4The XRD patterns of Examples 2-5, in which all the examples have a certain degree of diffraction peaks of 1T phase molybdenum sulfide, but as the amount of cobalt nitrate hexahydrate increases, the molybdenum oxide gradually increases.

[0045] Comparative Example 1

[0046] A method for preparing 2H phase molybdenum sulfide, comprising the following steps:

[0047] (1) Configure the reaction precursor: solvent water is 30 ml, ammonium molybdate tetrahydrate, and thiourea are 0.5 mmol and 3.5 mmol, respectively, 0.25 mmol of cobalt nitrate hexahydrate is added after stirring for 1 hour using a magnetic stirrer, and stirring for 40 minutes again.

[0048] (2) Put the reaction precursor into the reaction kettle, assemble it and react at 200 degrees Celsius for 22 hours.

[0049] (3) After the reaction is completed, take out the suspension in the reaction kettle and put it into a centrifuge tube, use a high-speed centrifuge at 6000r / min for 3 minutes, then use ethanol and deionized water to wash alternately for 3 times, and finally dry in a vacuum oven at 60 degrees Celsius.

[0050] From Figure 1 It can be seen that the XRD pattern of Example 1 has two diffraction peaks at 9° and 17.8°, which belong to the (002) and (004) diffraction peaks of 1T phase, respectively, while the (002) diffraction peak of Comparative Example 1 is 14°, which proves to be 2H phase.

[0051] Application Example

[0052] 1. Preparation of electrode

[0053] (1) Clean and dry the carbon paper with alcohol and deionized water;

[0054] (2) Prepare a catalyst slurry by ultrasonicating 1T phase molybdenum sulfide powder prepared in Example 1 (10 mg), deionized water (900 μL), and Nafion solution (100 μL) for 30 min;

[0055] (3) Uniformly coat the catalyst slurry on the cleaned carbon paper, and the loading amount is 1 mg / cm 2 , then dry overnight at room temperature to obtain the electrode.

[0056] 2. Preparation of electrolyte

[0057] Weigh a certain amount of potassium hydroxide and dilute it with water to prepare an aqueous solution with a concentration of 1 mol / L.

[0058] 3. Assembly of test device

[0059] The silver chloride electrode is used as the reference electrode, the graphite rod is used as the counter electrode, the electrode loaded with 1T phase molybdenum sulfide powder prepared in step 1 is used as the working electrode, and the potassium hydroxide solution prepared in step 2 is used as the electrolyte solution.

[0060] The above conditions are also tested for Comparative Example 1. The HER and OER tests are performed using the electrochemical workstation three-electrode system, and the results are shown in Figure 5 and Figure 6 .

[0061] Figure 5 is the HER performance test of Example 1 and Comparative Example 1, and the overpotential of Example 1 is 99 mV at 10 mA / cm 2 , which is better than 150 mV of Comparative Example 1, proving that Example 1 has better HER catalytic performance.

[0062] Figure 6 is the OER performance test of Example 1 and Comparative Example 1, and the overpotential of Example 1 is 320 mV at 10 mA / cm 2 , which is better than 370 mV of Comparative Example 1, and the starting potential of Example 1 is also lower than that of Comparative Example 1, proving that Example 1 has better OER catalytic performance.

[0063] The above content is only an example and description of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as the modifications or supplements do not deviate from the structure of the present application or exceed the scope defined by the present claims, and should belong to the protection scope of the present application.

Claims

1. A method for producing a 1T phase molybdenum sulfide, characterized by, The method comprises the following steps: A 1T-phase molybdenum sulfide is generated in a reaction process by a one-step hydrothermal method under the action of an applied magnetic field, with ammonium molybdate tetrahydrate and thiourea as molybdenum and sulfur sources respectively, and cobalt nitrate hexahydrate as an initiator, wherein the molar ratio of the ammonium molybdate tetrahydrate, the thiourea and the cobalt nitrate hexahydrate is 4:28:1-5, and the applied magnetic field is provided by two samarium-cobalt permanent magnets located on the same central axis and having opposite polarities, and the surface magnetic field strength of the samarium-cobalt permanent magnets is 0.35-0.45T.

2. The method of claim 1, wherein the 1T phase molybdenum sulfide is prepared by the following steps: The diameter of the samarium-cobalt permanent magnets is 25-30mm, and the height is 18-20mm. ​ 3. The method for preparing 1T phase molybdenum sulfide according to claim 1, characterized in that: The distance between the two samarium-cobalt permanent magnets is 58-62mm.

4. The method for preparing 1T phase molybdenum sulfide according to claim 1, characterized in that: The concentration of the ammonium molybdate tetrahydrate is 0.010-0.020mol / L, the concentration of the thiourea is 0.10-0.20mol / L, and the concentration of the cobalt nitrate hexahydrate is 0.001-0.01mol / L.

5. The method for preparing 1T phase molybdenum sulfide according to claim 1, characterized in that: The ammonium molybdate tetrahydrate and the thiourea need to be stirred for 45-60min before the cobalt nitrate hexahydrate is added.

6. The method for preparing 1T phase molybdenum sulfide according to claim 1, characterized in that: The temperature of the hydrothermal method is 180-220℃, and the time is 18-24h.

7. The method for preparing 1T phase molybdenum sulfide according to claim 1, characterized in that: After the 1T-phase molybdenum sulfide is obtained, it is washed with deionized water and anhydrous ethanol, and then dried.

8. Use of 1T phase molybdenum sulfide, characterized in that: The 1T-phase molybdenum sulfide prepared by the method of any one of claims 1-7 is used to prepare an oxygen evolution and hydrogen evolution bifunctional electrode.

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