Preparation method of molybdenum disulfide nanofiber for enhancing electro-catalytic hydrogen evolution performance

Abstract

The invention discloses a preparation method of a molybdenum disulfide nanofiber material for enhancing electro-catalytic hydrogen evolution performance. Molybdenum disulfide nanofibers are conveniently prepared by adopting an electrostatic spinning method matched with a heat treatment process, and molybdenum disulfide crystals are effectively packaged by a polymer matrix, so that the stability of a molybdenum disulfide catalyst can be improved. The molybdenum disulfide nanofiber has a conductive network, a large specific surface area and a stable structure due to fiber morphology, and has good catalytic activity in both an acid environment and an alkaline environment. The overpotential under the acidic condition is 202 mV, the Tafel slope is 93 mV.dec-1, the overpotential under the alkaline condition is 180 mV, and the Tafel slope is 83 mV.dec-1. In addition, the stability of the MoS2 nanofibers continuously working for 20 hours under acidic and alkaline conditions is superior to that of the Pt / C continuously working for 10 hours under the same condition, so that the actual application of the MoS2 nanofibers in the industry in the future is facilitated.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis and hydrogen evolution technology, specifically to the preparation and application of molybdenum disulfide nanofibers. Background Technology

[0002] In recent years, with the increasing prominence of energy issues, people have paid more and more attention to the research of clean energy, and hydrogen, as one of the renewable clean energy sources, has received widespread attention. Electrocatalytic water splitting to produce hydrogen is a promising method, but the entire reaction requires a highly efficient catalyst. Currently, the most effective catalyst is the precious metal platinum (Pt), but it is costly, resource-limited, and lacks long-term stability. Therefore, there is a need to develop highly efficient and stable catalysts.

[0003] In recent years, MoS2 materials have been considered an excellent candidate to replace noble metal catalysts. They are stable, non-toxic, and abundant, possessing a high electrochemical surface area and rich active sites, making them popular among researchers in the field of electrocatalytic hydrogen evolution. However, the low bulk conductivity and anisotropic electrotransport of MoS2 limit its catalytic efficiency. Therefore, researchers have developed numerous MoS2 composite catalysts to improve catalytic efficiency. Nanofibers possess a large specific surface area, excellent conductive network, and high stability; the molybdenum disulfide nanofibers prepared in this invention can effectively enhance the electrocatalytic hydrogen evolution performance. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the prior art by providing a method for preparing a highly stable molybdenum disulfide nanofiber electrocatalyst and its application in electrocatalytic hydrogen evolution.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A method for preparing molybdenum disulfide nanofibers includes the following steps: (1) N,N-dimethylformamide is placed in a bottle, PVP powder is added to obtain a mixed solution, dimethyl sulfoxide is placed in a bottle, and ATTM powder is added; (2) The solution is stirred and dissolved at ambient temperature, and then mixed and stirred again to obtain a precursor solution; (3) The precursor solution is loaded into a pipette for electrospinning to obtain ATTM / PVP nanofibers; (4) The nanofibers are placed in a tube furnace for heat treatment in an inert gas environment.

[0007] Furthermore, in step (1), the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is 3:2.

[0008] Furthermore, in step (1), the mass ratio of PVP to ATTM is 3:(1-3).

[0009] Furthermore, the stirring time in step (2) is approximately 2 hours, and the ambient temperature is 20°C.

[0010] Furthermore, the mixing time after mixing in step (2) is 6 hours.

[0011] Furthermore, the electrospinning voltage in step (3) is 20kV and the receiving distance is 20cm.

[0012] Furthermore, the temperature of the tubular furnace in step (4) is 450°C, and the holding time is 2 hours.

[0013] Furthermore, the temperature of the tubular furnace in step (4) is (800~1000)℃, and the holding time is 2 hours.

[0014] Molybdenum disulfide nanofibers were prepared according to the above method.

[0015] The method of using molybdenum disulfide nanofibers for electrocatalytic testing involves mixing the molybdenum disulfide nanofibers with Nafion to prepare an electrocatalyst ink, coating it on the electrode surface, and performing HER testing in a three-electrode system.

[0016] This invention offers the following advantages: It conveniently prepares molybdenum disulfide nanofibers using electrospinning combined with heat treatment, and the effective encapsulation of molybdenum disulfide crystals in the polymer matrix improves the stability of the molybdenum disulfide catalyst. Due to the conductive network, large specific surface area, and stable structure imparted by the fiber morphology, the molybdenum disulfide nanofibers exhibit good catalytic activity in both acidic and alkaline environments. Under acidic conditions, the overpotential is 202 mV and the Tafel slope is 93 mV·dec. -1 The overpotential under alkaline conditions is 180 mV, and the Tafel slope is 83 mV·dec. -1 Furthermore, MoS2 nanofibers exhibit better stability under both acidic and alkaline conditions for 20 hours than Pt / C nanofibers under the same conditions for 10 hours, which is beneficial for their future practical applications in industry. Attached Figure Description

[0017] Figure 1 (a) is a scanning electron microscope image of the ATTM / PVP nanofibers prepared in Preparation Example 1.

[0018] Figure 1 (b) is a scanning electron microscope image of the ATTM / PVP nanofibers prepared in Preparation Example 2.

[0019] Figure 1 (c) is a scanning electron microscope image of the ATTM / PVP nanofibers prepared in Preparation Example 3.

[0020] Figure 1(d) is a scanning electron microscope image of the molybdenum disulfide nanofibers prepared in Example 1.

[0021] Figure 1 (e) is a scanning electron microscope image of the molybdenum disulfide nanofibers prepared in Example 2.

[0022] Figure 1 (f) is a scanning electron microscope image of the molybdenum disulfide nanofibers prepared in Example 3.

[0023] Figure 2 (a) is a scanning electron microscope image of the molybdenum disulfide nanofibers prepared in Example 4.

[0024] Figure 2 (b) is a scanning electron microscope image of the molybdenum disulfide nanofibers prepared in Example 5.

[0025] Figure 3 High-magnification transmission electron microscopy image of the molybdenum disulfide nanofibers prepared in Example 4.

[0026] Figure 4 (a) LSV test of molybdenum disulfide nanofibers in Example 1 under acidic conditions.

[0027] Figure 4 (b) is the Tafel slope spectrum of the molybdenum disulfide nanofibers in Example 1 under acidic conditions.

[0028] Figure 5 Stability testing of the molybdenum disulfide nanofibers prepared in Example 4 under acidic conditions.

[0029] Figure 6 (a) LSV test of molybdenum disulfide nanofibers in Example 2 under acidic conditions.

[0030] Figure 6 (b) is the Tafel slope spectrum of the molybdenum disulfide nanofibers in Example 2 under acidic conditions.

[0031] Figure 7 Stability testing of the molybdenum disulfide nanofibers prepared in Example 4 under alkaline conditions. Detailed Implementation

[0032] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0033] Preparation Example 1

[0034] The preparation steps of molybdenum disulfide nanofibers are as follows: 1.5 g of PVP was added to 7.5 mL of N,N-dimethylformamide; 0.5 g of ATTM was added to 5 mL of dimethyl sulfoxide. After stirring for 2 hours, the two solutions were mixed and stirred for 6 hours to obtain the precursor solution. The precursor solution was loaded into a pipette for electrospinning at a voltage of 20 kV and a receiving distance of 20 cm. The obtained ATTM / PVP fiber membrane was placed in a tube furnace and heat-treated at 450 °C for 2 hours under an inert gas atmosphere, followed by heat treatment at 800 °C for 2 hours.

[0035] Preparation Example 2

[0036] The preparation steps of molybdenum disulfide nanofibers are as follows: 1.5 g of PVP was added to 7.5 mL of N,N-dimethylformamide; 1.0 g of ATTM was added to 5 mL of dimethyl sulfoxide. After stirring for 2 hours, the two solutions were mixed and stirred for 6 hours to obtain the precursor solution. The precursor solution was loaded into a pipette for electrospinning at a voltage of 20 kV and a receiving distance of 20 cm. The obtained ATTM / PVP fiber membrane was placed in a tube furnace and heat-treated at 450 °C for 2 hours under an inert gas atmosphere, followed by heat treatment at 800 °C for 2 hours.

[0037] Preparation Example 3

[0038] The preparation steps of molybdenum disulfide nanofibers are as follows: 1.5 g of PVP was added to 7.5 mL of N,N-dimethylformamide; 1.5 g of ATTM was added to 5 mL of dimethyl sulfoxide. After stirring for 2 hours, the two solutions were mixed and stirred for 6 hours to obtain the precursor solution. The precursor solution was loaded into a pipette for electrospinning at a voltage of 20 kV and a receiving distance of 20 cm. The obtained ATTM / PVP fiber membrane was placed in a tube furnace and heat-treated at 450 °C for 2 hours under an inert gas atmosphere, followed by heat treatment at 800 °C for 2 hours.

[0039] Based on the scanning electron microscope images of the molybdenum disulfide nanofibers prepared in Examples 1-3, as shown... Figure 1 As shown in c, when the mass of added ATTM is 1.5g (Preparation Example 3), better nanofiber morphology is achieved.

[0040] Preparation Example 4

[0041] The preparation steps of molybdenum disulfide nanofibers are as follows: 1.5 g of PVP was added to 7.5 mL of N,N-dimethylformamide; 1.5 g of ATTM was added to 5 mL of dimethyl sulfoxide. After stirring for 2 hours, the two solutions were mixed and stirred for 6 hours to obtain the precursor solution. The precursor solution was loaded into a pipette for electrospinning at a voltage of 20 kV and a receiving distance of 20 cm. The obtained ATTM / PVP fiber membrane was placed in a tube furnace and heat-treated at 450 °C for 2 hours under an inert gas atmosphere, followed by heat treatment at 900 °C for 2 hours.

[0042] Preparation Example 5

[0043] The preparation steps of molybdenum disulfide nanofibers are as follows: 1.5 g of PVP was added to 7.5 mL of N,N-dimethylformamide; 1.5 g of ATTM was added to 5 mL of dimethyl sulfoxide. After stirring for 2 hours, the two solutions were mixed and stirred for 6 hours to obtain the precursor solution. The precursor solution was loaded into a pipette for electrospinning at a voltage of 20 kV and a receiving distance of 20 cm. The obtained ATTM / PVP fiber membrane was placed in a tube furnace and heat-treated at 450 °C for 2 hours under an inert gas atmosphere, followed by heat treatment at 1000 °C for 2 hours.

[0044] Example 1

[0045] Based on the preparation example 4, HER detection was performed using molybdenum disulfide nanofibers in an acidic solution. To evaluate the catalytic activity of the molybdenum disulfide nanofibers, the electrocatalytic hydrogen evolution polarization curves and Tafel slopes of the molybdenum disulfide nanofibers were recorded. The results were also compared with those of 20% Pt / C, molybdenum disulfide nanoflowers prepared by hydrothermal method, and nanofibers prepared in Examples 3 and 5. Figure 4 As shown, molybdenum disulfide nanofibers exhibit overpotential values ​​and Tafel slopes only higher than Pt / C, superior to nanoflowers and nanofibers from Preparation Examples 3 and 5.

[0046] To investigate the stability of molybdenum disulfide nanofibers, the stability of the molybdenum disulfide nanofibers prepared in Example 4 and a commercially available mature Pt / C catalyst were tested and compared. Figure 5 It can be seen that the current density of molybdenum disulfide nanofibers changes by 45% within 20 hours, while the current density of Pt / C catalyst decays to 0 within 5 hours. This indicates that molybdenum disulfide nanofibers have excellent stability under acidic conditions.

[0047] Example 2

[0048] Similarly, HER testing can be performed under alkaline conditions, such as... Figure 6As shown, the overpotential of molybdenum disulfide nanofibers at a current density of 10 mA / cm² is 180 mV, which is superior to other materials. Stability tests were also conducted, such as... Figure 7 As shown, the current density of molybdenum disulfide nanofibers changed by 30% after 20 hours of operation, while Pt / C decreased by 54% after 10 hours under the same conditions.

[0049] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A molybdenum disulfide nanofiber catalyst, characterized in that, The catalyst was prepared by in-situ encapsulating ATTM into PVP polymer nanofibers with highly uniform size and spatial distribution using electrospinning, resulting in MoS2 nanofibers with abundant surface active sites, which is highly beneficial for electrocatalytic hydrogen evolution.

2. A method for preparing molybdenum disulfide nanofibers as described in claim 1, characterized in that, Includes the following steps: (1) Preparation of precursor solution; (2) Electrospinning using precursor solutions; (3) Heat treatment is performed on the ATTM / PVP nanofibers obtained by electrospinning to obtain molybdenum disulfide nanofibers.

3. The method for producing molybdenum disulfide nanofibers as described in claim 2, characterized in that, The specific method for preparing the precursor solution in step (1) is to dissolve PVP powder in an appropriate amount of N,N-dimethylformamide and ATTM powder in an appropriate amount of dimethyl sulfoxide. After stirring for 2 hours, the two solutions are mixed and stirred for 6 hours.

4. The method for producing molybdenum disulfide nanofibers as described in claim 3, characterized in that, The volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is 3:2, and the mass ratio of PVP to ATTM is 1:(1-3).

5. The method for producing molybdenum disulfide nanofibers as described in claim 2, characterized in that, Step (2) The voltage for electrospinning is 20kV and the receiving distance is 20cm.

6. The method for producing molybdenum disulfide nanofibers as described in claim 2, characterized in that, The heat treatment temperatures in step (3) are 450℃ and (800~1000)℃, and the holding time is 2 hours for both.

7. A method for using the molybdenum disulfide nanofiber electrocatalyst according to claim 1, characterized in that, The catalyst is placed in an electrolytic cell containing an acidic or alkaline solution for HER testing.

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