CN111905767A - Nano pompon-shaped molybdenum sulfide/wood-based carbon porous electrode material and preparation method and application thereof - Google Patents

Abstract

The invention discloses a nanometer fluffy spherical molybdenum sulfide/wood-based carbon porous electrode material and a preparation method and application thereof. The porous electrode material is composed of porous carbonized wood chips and nano-puff spherical molybdenum sulfide that grows uniformly on the surface thereof. The diameter of the nano-puff spherical molybdenum sulfide is 0.1-3 μm, and the nano-puff spherical molybdenum sulfide is composed of molybdenum sulfide nano-sheets. In the invention, the nano-flaky molybdenum sulfide is stacked into nano-puff balls and evenly loaded on the surface of the carbonized wood chips, which effectively solves the drawbacks of traditional powder catalysts; at the same time, the puff-shaped molybdenum sulfide makes the edges of the flaky molybdenum sulfide fully exposed to the outside. , increasing the proportion of active edge exposure, so that the prepared three-dimensional self-supporting electrolysis water hydrogen evolution catalyst has good catalytic performance; at the same time, the carbonized wood material with good conductivity improves the conductivity of molybdenum sulfide as a catalyst material.

Description

A nano-puff spherical molybdenum sulfide/wood-based carbon porous electrode material and preparation method thereof law and application

technical field

The invention belongs to the field of catalysts, and in particular relates to a nanometer fluffy molybdenum sulfide/wood-based carbon porous electrode material and a preparation method and application thereof.

Background technique

With the excessive consumption of global energy and the problem of environmental pollution caused by the consumption of traditional energy, the search for alternative energy sources with low environmental pollution and high energy density has become the focus of global attention. Hydrogen continues to receive attention as a new energy source with high energy density and zero carbon emissions. However, the traditional hydrogen production process is generally coal gasification, natural gas and steam reforming, but these will cause the emission of carbides and still cause certain pollution to the environment. Hydrogen evolution from water electrolysis is regarded as one of the most promising hydrogen production technologies as an environmentally friendly and efficient way to produce hydrogen. From a chemical thermodynamic point of view, water electrolysis is a non-spontaneous reaction that requires energy (electrical) input, so an efficient catalyst is needed to reduce energy consumption. Noble metal (platinum-based metal) catalysts are currently recognized as the most active catalysts, but their cost and stability limit their further development. Therefore, the development of a non-precious metal catalyst that is economical, has good performance and good stability is the key issue to solve the sustainable development of the water electrolysis hydrogen production industry.

Most of the traditional electrocatalysts are in powder form, and binders are often required in the preparation process of electrodes. The biggest disadvantage is that the powders are superimposed on each other, which inevitably leads to the existence of resistance between catalyst particles and the formation of active sites. Covering, greatly affects the performance of the catalyst's intrinsic properties, reduces the efficiency of the material and increases the cost of hydrogen production. With in-depth research, people make catalysts grow on conductive substrates with high specific surface area (nickel foam, copper foam, carbon cloth, etc.), and then use them directly as electrodes, which solves the drawbacks of traditional powder catalysts. However, the fabrication process of conductive substrates such as foamed nickel is complicated and the cost is high, so an alternative cheap conductive substrate is a problem before people.

Molybdenum sulfide, as a highly active catalyst for hydrogen evolution in water electrolysis, has been developed into catalyst materials with different chemical ratios and different morphologies due to its ideal Gipps free energy. However, its disadvantage is the powdery particles, which seriously limit the full play of the intrinsic catalytic activity in practical application. After a lot of research, it is found that the microscopic molybdenum sulfide nanosheets are catalytically active for the flaky molybdenum sulfide edges, but the basal plane is catalytically inert. Therefore, increasing the number and ratio of exposed molybdenum sulfide edges can improve the catalyst activity. The essential. Furthermore, the conductivity of molybdenum sulfide is relatively poor, and improving its conductivity is also the key to improving the catalytic performance.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a nanometer fluffy molybdenum sulfide/wood-based carbon porous electrode material.

Another object of the present invention is to provide a method for preparing the above-mentioned nano-puff spherical molybdenum sulfide/wood-based carbon porous electrode material. The invention uses wood abundant in nature as raw material, calcined at high temperature under the protection of inert gas to obtain porous carbon material, solves the problems of high cost and complicated process of foam metal as a matrix, and as a conductive matrix, it has higher specific surface area and higher Conductivity.

Another object of the present invention is to provide the application of the above-mentioned nano-puff spherical molybdenum sulfide/wood-based carbon porous electrode material.

The object of the present invention is realized through the following scheme:

A nano-velvet spherical molybdenum sulfide/wood-based carbon porous electrode material, which is composed of porous carbonized wood chips and nano-velvet spherical molybdenum sulfide grown uniformly on the surface thereof, the diameter of the nano-velvet spherical molybdenum sulfide is 0.1-3 μm, and the nano-velvet spherical molybdenum sulfide is 0.1-3 μm in diameter. Spherical molybdenum sulfide consists of molybdenum sulfide nanosheets.

In the nanometer fluffy spherical molybdenum sulfide/wood-based carbon porous electrode material, the molybdenum sulfide grows uniformly on the surface of the porous carbonized wood chips, the molybdenum sulfide is flaky, and the flaky molybdenum sulfide is clustered together in a regular spherical shape. The nanometer size exposes the active surface area more fully, and the spherical stacking of nanosheets exposes more active edges, which solves the problem that the catalyst does not work to the fullest due to the overlapping of active sites.

A preparation method of the above-mentioned nano-puff spherical molybdenum sulfide/wood-based carbon porous electrode material, comprising the following steps:

(1) Pretreatment of wood: put the dried wood in a tube furnace, calcined at high temperature under the protection of nitrogen or inert gas, then naturally cooled and taken out, and then cut into 0.1-5mm thick carbonization along the direction perpendicular to the growth direction of the wood Wood chips, the obtained carbonized wood chips are washed with water, ethanol and acetone respectively until the liquid is in a clear state, and finally the carbonized wood chips are dried for subsequent use;

(2) configure the mixed aqueous solution containing 0.005-1mol/L sodium molybdate dihydrate and 0.01-1mol/L thiourea, immerse the carbonized wood chips dried for subsequent use in the mixed solution in the step (1), and leave standstill under vacuum conditions for 0 -60min to make the mixed solution fully enter into the porous carbonized wood chips, then put the mixed solution and the carbonized wood chips in a high-pressure reactor for airtight reaction, after the reaction, purify the obtained carbonized wood chips to obtain nano-puff spherical molybdenum sulfide/wood-based carbon porous electrode Material.

The wood described in step (1) refers to at least one of natural basswood, poplar, eucalyptus;

The dried wood in step (1) refers to drying the wood in a drying oven at 60-120° C. for 0.5-12 hours.

The high-temperature calcination described in step (1) refers to calcination at 500-1500°C for 1-12 hours, and the heating rate is 1-25°C/min; preferably, calcination is performed at 1000°C for 6 hours, and the heating rate is 5°C/min.

The washing described in step (1) is preferably washing under ultrasonic conditions.

The drying for use in step (1) refers to the use of vacuum drying at 60-100° C. for 1-24 hours before use.

The concentration of sodium molybdate dihydrate in the mixed aqueous solution described in step (2) is preferably 0.0214-0.0414 mol/L, and the concentration of thiourea is preferably 0.13-0.17 mol/L.

The carbonized wood chips described in step (2) further include a purification step before being dipped into the mixed solution. The specific purification steps are as follows: ultrasonically treat the carbonized wood chips in concentrated nitric acid (40-86wt%) for 0-10h to remove surface impurities , to improve the hydrophilicity of the surface, so as to pave the way for the later generation of fluffy molybdenum sulfide; then ultrasonically treat it with water and a low-boiling organic solvent for 1-60 minutes, and then vacuum dry at 60-100 ° C for 1-24 hours for use. The boiling point organic solvent refers to at least one of ethanol, acetone, diethyl ether, chloroform and the like.

In step (2), the mixed solution is allowed to stand for 0-60 min under vacuum conditions to fully enter the porous carbonized wood chips, which solves the problems of aggregation and uneven growth of catalysts grown in traditional high temperature environments.

The closed reaction in step (2) refers to the reaction at 50-300°C for 1-24 hours; preferably, the reaction at 200°C for 12 hours.

The purification described in step (2) refers to taking out the carbonized wood chips after the reaction, fully washing with water and ethanol to remove excess residues on the surface, and then vacuum drying at 60-100° C. for 1-24 hours to obtain nano-fleece vulcanization. Molybdenum/wood-based carbon porous electrode materials.

The application of the above-mentioned nano-fleece spherical molybdenum sulfide/wood-based carbon porous electrode material as a catalyst for electrolysis of water for hydrogen evolution.

The mechanism of the present invention is:

In the invention, the nano-flaky molybdenum sulfide is stacked into nano-puff balls and evenly loaded on the surface of the carbonized wood, which effectively solves the drawbacks of traditional powder catalysts; meanwhile, the puff-shaped molybdenum sulfide makes the edges of the flaky molybdenum sulfide fully exposed to the outside. , increase the proportion of active edge exposure; with carbonized wood as the base, it has a larger specific surface area, which increases the number of exposed active sites, and the carbonized wood material with good electrical conductivity improves the performance of molybdenum sulfide as a catalyst material. Conductivity.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

The invention discloses a three-dimensional self-supporting electrolytic water hydrogen evolution catalyst material prepared by using carbonized wood chips as a carrier, and relates to a carbonized wood chip obtained by high-temperature carbonization of natural wood as a raw material and a preparation method, as well as a carbonized wood chip as a carrier and a molybdenum dihydrate as a carrier. Sodium and thiourea are used as raw materials, and molybdenum sulfide is grown in-situ on the inner and outer walls of carbonized wood by hydrothermal method in a high-pressure reactor to prepare a three-dimensional self-supporting hydrogen evolution catalyst material for electrolysis of water. The electrolytic water hydrogen evolution catalyst prepared by the invention has high catalytic performance, abundant raw materials, high specific surface area, good electrical conductivity, no addition of binder, simple preparation method, raw materials from biomass wood-based materials, low cost, energy saving and environmental protection . The carbonized wood chips obtained by high-temperature carbonization are used as a carrier, which is not only rich in raw materials, simple in production, and superior in electrical properties, but also replaces commercial nickel foam, copper foam, carbon cloth... The specific surface area exposes more active sites for the hydrogen evolution of water electrolysis, so that the prepared three-dimensional self-supporting electrolysis water hydrogen evolution catalyst has good catalytic performance, and provides a good route for the preparation of the three-dimensional self-supporting water electrolysis hydrogen evolution catalyst. .

Description of drawings

1 is a scanning electron microscope image (500 times) of blank carbonized wood chips after the concentrated nitric acid treatment in step (2) of Example 1.

FIG. 2 is a SEM image (1000 times) of the nano-puff spherical molybdenum sulfide/wood-based carbon porous electrode prepared in Example 1. FIG.

3 is the SEM images (2000 times and 5000 times) of the nano-puff spherical molybdenum sulfide/wood-based carbon porous electrode prepared in Example 1.

FIG. 4 is the SEM images (2000 times and 5000 times) of the nano-puff spherical molybdenum sulfide/wood-based carbon porous electrode prepared in Example 2. FIG.

5 is a linear sweep voltammetry diagram of the porous electrode materials prepared in Examples 1 to 5 of the present invention.

FIG. 6 is a SEM image (500 times) of the electrode prepared in Comparative Example 1. FIG.

Detailed ways

The present invention will be described in further detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. If the specific conditions are not indicated in the examples, it is carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used without the manufacturer's indication are conventional products that can be purchased from the market.

Example 1

(1) Using natural basswood as raw material, it needs to be pretreated in a drying oven at 103 ° C for 12 hours before calcination. Then, under the protection of nitrogen gas, the heating rate was 5°C/min, calcined at 1000°C for 6 hours in a tube furnace, and cooled naturally at room temperature. Then use a small table saw to cut into 1mm thick carbonized wood chips along the direction perpendicular to the wood growth, and then ultrasonically treat with deionized water, ethanol and acetone respectively, until the ultrasonically treated solution is in a clear state, and then vacuum dry at 75 °C for 12 hours. .

(2) The prepared carbonized wood chips were first ultrasonically treated with concentrated nitric acid (63wt%) for 2 hours, then ultrasonically treated with deionized water, ethanol and acetone for 15 minutes respectively, and the carbonized wood chips were dried for later use. A mixed aqueous solution containing 0.0214 mol/L sodium molybdate dihydrate and 0.13 mol/L thiourea was prepared. The treated carbonized wood chips and the mixed solution are mixed together, and vacuum impregnation is realized by vacuuming for 5 minutes, so that the mixed solution can fully enter the porous carbonized wood chips, and then the mixed solution and the carbonized wood chips are transferred into the autoclave together. The temperature was maintained at 200°C for 12 hours. Natural cooling at room temperature, taking out the carbonized wood chips, fully washing with deionized water to remove excess residues on the surface, and vacuum drying at 75 ° C for 12 hours to obtain a composite material (nano-puffed molybdenum sulfide/nano-puffed molybdenum sulfide/ wood-based carbon porous electrode materials).

The scanning electron microscope image (500 times) of the blank carbonized wood chips after the concentrated nitric acid treatment in the step (2) of Example 1 is shown in Figure 1. As can be seen from Figure 1, the carbonized wood has many holes, and these porous holes can be Active substances provide many attachment points, so naturally their active sites can be increased.

The SEM images (1000 times, 2000 times and 5000 times) of the composite material obtained in step (2) with puff-like molybdenum sulfide supported on the surface of carbonized wood chips are shown in Figure 2 and Figure 3, respectively, from Figure 2 and Figure 3 It can be seen that the molybdenum sulfide spheres are evenly loaded on the inner and outer surfaces, and some spheres grow outward continuously, and the connection area between the spheres is very small, and some are even point connections, so more sphere surfaces are exposed, It also exposes more active sites, and also increases the number of active sites to a certain extent.

Example 2

(1) Using natural basswood as raw material, it needs to be pretreated in a drying oven at 103 ° C for 12 hours before calcination. Then, under the protection of nitrogen gas, the heating rate was 5°C/min, calcined at 1000°C for 6 hours in a tube furnace, and cooled naturally at room temperature. Then use a small table saw to cut into 1mm thick carbonized wood chips along the direction perpendicular to the wood growth, and then ultrasonically treat with deionized water, ethanol and acetone respectively, until the ultrasonically treated solution is in a clear state, and then vacuum dry at 75 °C for 12 hours. .

(2) The prepared carbonized wood chips were first ultrasonically treated with concentrated nitric acid (63wt%) for 2 hours, then ultrasonically treated with deionized water, ethanol and acetone for 15 minutes respectively, and the carbonized wood chips were dried for later use. A mixed aqueous solution containing 0.0214 mol/L sodium molybdate dihydrate and 0.15 mol/L thiourea was prepared. The treated carbonized wood chips and the mixed solution are mixed together, and vacuum impregnation is realized by vacuuming for 5 minutes, so that the mixed solution can fully enter the porous carbonized wood chips, and then the mixed solution and the carbonized wood chips are transferred into the autoclave together. The temperature was maintained at 200°C for 12 hours. Natural cooling at room temperature, taking out the carbonized wood chips, fully washing with deionized water to remove excess residues on the surface, and vacuum drying at 75 ° C for 12 hours to obtain a composite material (nano-puffed molybdenum sulfide/nano-puffed molybdenum sulfide/ wood-based carbon porous electrode materials).

The SEM images (2000 times and 5000 times) of the nano-fleece spherical molybdenum sulfide/wood-based carbon porous electrode prepared in Example 2 are shown in FIG. 4 .

Example 3

(1) Using natural basswood as raw material, it needs to be pretreated in a drying oven at 103 ° C for 12 hours before calcination. Then, under the protection of nitrogen gas, the heating rate was 5°C/min, calcined at 1000°C for 6 hours in a tube furnace, and cooled naturally at room temperature. Then use a small table saw to cut into 1mm thick carbonized wood chips along the direction perpendicular to the wood growth, and then ultrasonically treat with deionized water, ethanol and acetone respectively, until the ultrasonically treated solution is in a clear state, and then vacuum dry at 75 °C for 12 hours. .

(2) The prepared carbonized wood chips were first ultrasonically treated with concentrated nitric acid (63wt%) for 2 hours, then ultrasonically treated with deionized water, ethanol and acetone for 15 minutes respectively, and the carbonized wood chips were dried for later use. A mixed aqueous solution containing 0.0214 mol/L sodium molybdate dihydrate and 0.17 mol/L thiourea was prepared. The treated carbonized wood chips and the mixed solution are mixed together, and vacuum impregnation is realized by vacuuming for 5 minutes, so that the mixed solution can fully enter the porous carbonized wood chips, and then the mixed solution and the carbonized wood chips are transferred into the autoclave together. The temperature was maintained at 200°C for 12 hours. Natural cooling at room temperature, taking out the carbonized wood chips, fully washing with deionized water to remove excess residues on the surface, and vacuum drying at 75 ° C for 12 hours to obtain a composite material (nano-puffed molybdenum sulfide/nano-puffed molybdenum sulfide/ wood-based carbon porous electrode materials). The formation of nano-poll-filled molybdenum sulfide can also be seen on the SEM image of the composite.

Example 4

(1) Using natural basswood as raw material, it needs to be pretreated in a drying oven at 103 ° C for 12 hours before calcination. Then, under the protection of nitrogen gas, the heating rate was 5°C/min, calcined at 1000°C for 6 hours in a tube furnace, and cooled naturally at room temperature. Then use a small table saw to cut into 1mm thick carbonized wood chips along the direction perpendicular to the wood growth, and then ultrasonically treat with deionized water, ethanol and acetone respectively, until the ultrasonically treated solution is in a clear state, and then vacuum dry at 75 °C for 12 hours. .

(2) The prepared carbonized wood chips were first ultrasonically treated with concentrated nitric acid (63wt%) for 2 hours, then ultrasonically treated with deionized water, ethanol and acetone for 15 minutes respectively, and the carbonized wood chips were dried for later use. A mixed aqueous solution containing 0.0314 mol/L sodium molybdate dihydrate and 0.15 mol/L thiourea was prepared. The treated carbonized wood chips and the mixed solution are mixed together, and vacuum impregnation is realized by vacuuming for 5 minutes, so that the mixed solution can fully enter the porous carbonized wood chips, and then the mixed solution and the carbonized wood chips are transferred into the autoclave together. The temperature was maintained at 200°C for 12 hours. Natural cooling at room temperature, taking out the carbonized wood chips, fully washing with deionized water to remove excess residues on the surface, and vacuum drying at 75 ° C for 12 hours to obtain a composite material (nano-puffed molybdenum sulfide/nano-puffed molybdenum sulfide/ wood-based carbon porous electrode materials). The formation of nano-poll-filled molybdenum sulfide can also be seen on the SEM image of the composite.

Example 5

(1) Using natural basswood as raw material, it needs to be pretreated in a drying oven at 103 ° C for 12 hours before calcination. Then, under the protection of nitrogen gas, the heating rate was 5°C/min, calcined at 1000°C for 6 hours in a tube furnace, and cooled naturally at room temperature. Then use a small table saw to cut into 1mm thick carbonized wood chips along the direction perpendicular to the wood growth, and then ultrasonically treat with deionized water, ethanol and acetone respectively, until the ultrasonically treated solution is in a clear state, and then vacuum dry at 75 °C for 12 hours. .

(2) The prepared carbonized wood chips were first ultrasonically treated with concentrated nitric acid (63wt%) for 2 hours, then ultrasonically treated with deionized water, ethanol and acetone for 15 minutes respectively, and the carbonized wood chips were dried for later use. A mixed aqueous solution containing 0.0414 mol/L sodium molybdate dihydrate and 0.15 mol/L thiourea was prepared. The treated carbonized wood chips and the mixed solution are mixed together, and vacuum impregnation is realized by vacuuming for 5 minutes, so that the mixed solution can fully enter the porous carbonized wood chips, and then the mixed solution and the carbonized wood chips are transferred into the autoclave together. The temperature was maintained at 200°C for 12 hours. Natural cooling at room temperature, taking out the carbonized wood chips, fully washing with deionized water to remove excess residues on the surface, and vacuum drying at 75 ° C for 12 hours to obtain a composite material (nano-puffed molybdenum sulfide/nano-puffed molybdenum sulfide/ wood-based carbon porous electrode materials). The SEM images of the composites can also see the formation of nano-poll-loaded molybdenum sulfide.

The linear sweep voltammogram of the nano-puff ball-like molybdenum sulfide/wood-based carbon porous electrode material obtained in Examples 1-5 is shown in Figure 5. It can be seen from Figure 5 that the nanometer fuzz prepared in Examples 1-5 of the present invention The puff-like molybdenum sulfide/wood-based carbon porous electrode materials have good hydrogen evolution performance.

Comparative Example 1

Delete step (1) in Example 1, then replace "treated carbonized wood chips" in "mix the treated carbonized wood chips and mixed solution" with "foam nickel" in step (2), and the rest are the same as Example 1 is the same.

The SEM image of the product obtained in Comparative Example 1 is shown in Figure 6. It can be seen from Figure 6 that even with the same experimental method, when the carrier is different, the morphology of the obtained molybdenum sulfide is completely different.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, The simplification should be equivalent replacement manners, which are all included in the protection scope of the present invention.

Claims (10)

1. The nano velvet spherical molybdenum sulfide/wood-based carbon porous electrode material is characterized by consisting of a porous carbonized wood chip and nano velvet spherical molybdenum sulfide uniformly grown on the surface of the porous carbonized wood chip, wherein the diameter of the nano velvet spherical molybdenum sulfide is 0.1-3 mu m, and the nano velvet spherical molybdenum sulfide consists of molybdenum sulfide nanosheets.

2. The preparation method of the nano-fluff spherical molybdenum sulfide/wood-based carbon porous electrode material according to claim 1, characterized by comprising the following steps:

(1) pretreating wood: placing the dried wood in a tubular furnace, calcining at high temperature under the protection of nitrogen or inert gas, naturally cooling and taking out, cutting the wood into carbonized wood chips with the thickness of 0.1-5mm along the direction vertical to the growth direction of the wood, respectively washing the carbonized wood chips with water, ethanol and acetone until the liquid is in a clear state, and finally drying the carbonized wood chips for later use;

(2) preparing a mixed aqueous solution containing 0.005-1mol/L sodium molybdate dihydrate and 0.01-1mol/L thiourea, soaking the carbonized wood chips dried for standby in the step (1) in the mixed solution, standing for 0-60min under a vacuum condition to ensure that the mixed solution fully enters the porous carbonized wood chips, then placing the mixed solution and the carbonized wood chips in a high-pressure reaction kettle for closed reaction, and purifying the carbonized wood chips after the reaction is finished to obtain the nano velvet spherical molybdenum sulfide/wood-based carbon porous electrode material.

3. The preparation method of the nano-fluff-ball-shaped molybdenum sulfide/wood-based carbon porous electrode material according to claim 2, characterized by comprising the following steps:

the high-temperature calcination in the step (1) refers to calcination at the temperature of 500-1500 ℃ for 1-12h, and the heating rate is 1-25 ℃/min.

4. The preparation method of the nano-fluff-ball-shaped molybdenum sulfide/wood-based carbon porous electrode material according to claim 2, characterized by comprising the following steps:

the wood in the step (1) is at least one of natural basswood, poplar and eucalyptus.

5. The preparation method of the nano-fluff-ball-shaped molybdenum sulfide/wood-based carbon porous electrode material according to claim 2, characterized by comprising the following steps:

the dried wood in the step (1) is dried in a drying oven at 60-120 ℃ for 0.5-12 hours;

the drying for standby in the step (1) refers to the standby after vacuum drying for 1-24 hours at the temperature of 60-100 ℃.

6. The preparation method of the nano-fluff-ball-shaped molybdenum sulfide/wood-based carbon porous electrode material according to claim 2, characterized by comprising the following steps:

the concentration of the sodium molybdate dihydrate in the mixed water solution in the step (2) is 0.0214-0.0414 mol/L, and the concentration of the thiourea is 0.13-0.17 mol/L.

7. The preparation method of the nano-fluff-ball-shaped molybdenum sulfide/wood-based carbon porous electrode material according to claim 2, characterized by comprising the following steps:

the carbonized wood chips in the step (2) also comprise a purification step before being dipped into the mixed solution, and the specific purification step is as follows: ultrasonically treating carbonized wood chips in concentrated nitric acid for 0-10h to remove surface impurities, then respectively ultrasonically treating with water and a low-boiling-point organic solvent for 1-60min, and vacuum drying at 60-100 ℃ for 1-24h for later use, wherein the low-boiling-point organic solvent is at least one of ethanol, acetone, diethyl ether and chloroform.

8. The preparation method of the nano-fluff-ball-shaped molybdenum sulfide/wood-based carbon porous electrode material according to claim 2, characterized by comprising the following steps:

the closed reaction in the step (2) refers to a reaction at 50-300 ℃ for 1-24 h.

9. The preparation method of the nano-fluff-ball-shaped molybdenum sulfide/wood-based carbon porous electrode material according to claim 2, characterized by comprising the following steps:

and (2) the purification in the step (2) is to take out the carbonized wood chips after the reaction is finished, fully wash the carbonized wood chips with water and ethanol to remove redundant residues on the surface, and then dry the carbonized wood chips in vacuum at 60-100 ℃ for 1-24 hours to obtain the nano napped molybdenum sulfide/wood-based carbon porous electrode material.

10. The use of the nano-fluff-ball-shaped molybdenum sulfide/wood-based carbon porous electrode material as claimed in claim 1 as a catalyst for hydrogen evolution by electrolysis of water.

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