Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a preparation method of a molybdenum disulfide/expanded graphite hydrogen evolution electrode, which takes expanded graphite with excellent conductivity as a carrier, and can improve the conductivity of molybdenum disulfide after the molybdenum disulfide is loaded on the carrier, thereby improving the electrochemical hydrogen evolution efficiency of the molybdenum disulfide.
The invention is realized by the following steps:
a preparation method of a molybdenum disulfide/expanded graphite hydrogen evolution electrode specifically comprises the following steps:
s1, tabletting expanded graphite:
s11, adding expanded graphite and acetylene black into solvent absolute ethyl alcohol, stirring for 1-2 hours at room temperature, adding polytetrafluoroethylene during stirring to obtain a dispersion liquid, wherein the mass ratio of the expanded graphite to the acetylene black to the polytetrafluoroethylene is 1: 0.1-0.15: 5-7;
s12, heating the obtained dispersion liquid at a constant temperature of 90 ℃ to volatilize the absolute ethyl alcohol in the dispersion liquid, and drying to obtain expanded graphite mixture powder;
s13, putting the dried expanded graphite mixture powder into a cold mould pressing die for pressing and forming treatment, wherein the diameter of the die is 50mm, the pressing pressure is set to be 8-10 Mpa, and the pressing time is 15-20 min, so that an expanded graphite pressing piece is obtained;
s14, sintering the expanded graphite pressing piece at 375-380 ℃ for 120-130 min, cutting the sintered piece into a preset shape, and using the cut sintered piece as an expanded graphite base pressing piece;
s2, preparing the molybdenum disulfide/expanded graphite hydrogen evolution electrode:
the dosage of the raw materials is as follows: the mass ratio of the expanded graphite matrix tablet to the ammonium molybdate to the thiourea is 1: 0.618 ~ 2.472: 1.14-4.56, wherein the addition amount of ammonium molybdate corresponding to each square centimeter of expanded graphite matrix tablet is 0.071 mmol-0.284 mmol;
s21, adding ammonium molybdate and thiourea into deionized water, and magnetically stirring at room temperature to fully dissolve the ammonium molybdate and the thiourea;
s22, placing the expanded graphite matrix tablet in an ethanol solution, performing ultrasonic treatment for 1-2 h, and drying;
s23, adding a mixed solution of ammonium molybdate and thiourea into the dried expanded graphite substrate tablet, heating at 199-201 ℃ for 24 hours, cooling to room temperature, and directly loading molybdenum disulfide on the expanded graphite substrate tablet;
and S24, respectively cleaning the expanded graphite matrix tablet loaded with the molybdenum disulfide by using deionized water and absolute ethyl alcohol, and drying to obtain the molybdenum disulfide/expanded graphite hydrogen evolution electrode.
Preferably, the preparation method of the expanded graphite comprises the following steps:
fully mixing natural crystalline flake graphite, potassium permanganate and ammonium nitrate at room temperature, slowly adding perchloric acid, stirring at the temperature of 30-35 ℃, wherein the stirring speed is 200r/min, performing oxidation intercalation reaction by using the potassium permanganate as an oxidant, the perchloric acid as an intercalation agent and the ammonium nitrate as an auxiliary intercalation agent, and controlling the reaction time to be 60-70 min;
after the oxidation intercalation reaction is finished, naturally cooling the mixed liquid to room temperature, washing the mixture to be neutral by deionized water, then carrying out suction filtration and dehydration on the mixture, and drying at 70 ℃ to obtain expandable graphite; and (3) puffing the expandable graphite at 950 ℃ to obtain the expanded graphite.
Preferably, the drying temperature of the step S12 is 65-70 ℃, and the drying time is 23-25 h.
Preferably, the temperature is raised from room temperature to the sintering temperature of 375-380 ℃ at a rate of 1 ℃/min during the sintering in step S14.
Preferably, the step S14 cuts the sintered piece into a square piece of 20mm × 20 mm.
Preferably, the drying temperature of step S22 is 90-95 ℃, and the drying time is 10-15 min.
Preferably, in the step S23, the temperature is increased from room temperature to 199-201 ℃ at a speed of 5 ℃/min.
Preferably, the ammonium molybdate is added in an amount of 0.142 millimoles per square centimeter of expanded graphite substrate pellet.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention firstly adopts an oxidation intercalation method to prepare expandable graphite, then obtains the expanded graphite through high-temperature expansion, then carries out tabletting treatment on the expandable graphite, then adopts a hydrothermal synthesis method to load molybdenum disulfide on the surface of the expandable graphite, finally prepares a molybdenum disulfide/expanded graphite hydrogen evolution electrode, and prepares a series of electrochemical hydrogen evolution materials by adjusting the growth amount of the molybdenum disulfide on an expanded graphite matrix material, wherein the addition amount range of ammonium molybdate corresponding to each square centimeter of expanded graphite matrix tabletting is 0.071 millimole-0.284 millimole. The preparation method is simple in preparation process and low in cost, and the composite material electrode prepared by the method can improve the catalytic hydrogen evolution efficiency of the molybdenum disulfide and can effectively solve the problem of poor conductivity of the molybdenum disulfide.
2. The expanded graphite prepared by the invention has high conductivity, does not contain sulfur, is environment-friendly, and the strength of the electrode matrix material prepared by pressing the expanded graphite into a sheet after blending treatment is higher than that of a common carbon material;
3. the composite material electrode prepared by the invention has good hydrogen evolution performance, is not influenced by the pH of an electrolyte, and can electrolyze water to produce hydrogen in acid and alkali environment.
Detailed Description
Exemplary embodiments, features and performance aspects of the present invention will be described in detail below with reference to the accompanying drawings.
The invention provides a preparation method of a molybdenum disulfide/expanded graphite hydrogen evolution electrode, which specifically comprises the following steps:
firstly, preparing expanded graphite by the following steps:
fully mixing natural crystalline flake graphite, potassium permanganate and ammonium nitrate at room temperature, slowly adding perchloric acid, stirring at the temperature of 30-35 ℃, wherein the stirring speed is 200r/min, performing oxidation intercalation reaction by using the potassium permanganate as an oxidant, the perchloric acid as an intercalation agent and the ammonium nitrate as an auxiliary intercalation agent, and controlling the reaction time to be 60-70 min;
after the oxidation intercalation reaction is finished, naturally cooling the mixed liquid to room temperature, washing the mixture to be neutral by deionized water, then carrying out suction filtration and dehydration on the mixture, and drying at 70 ℃ to obtain expandable graphite; the expandable graphite is expanded at 950 ℃ to obtain the expanded graphite, and the prepared expanded graphite has high conductivity, does not contain sulfur and is environment-friendly.
S1, tabletting expanded graphite:
s11, adding expanded graphite and acetylene black into solvent absolute ethyl alcohol, stirring for 1-2 hours at room temperature, adding polytetrafluoroethylene during stirring to obtain a dispersion liquid, wherein the mass ratio of the expanded graphite to the acetylene black to the polytetrafluoroethylene is 1: 0.1-0.15: 5-7;
s12, heating the obtained dispersion liquid at a constant temperature of 90 ℃ to volatilize absolute ethyl alcohol in the dispersion liquid, and then drying to obtain expanded graphite mixture powder, wherein the drying temperature is 65-70 ℃, and the drying time is 23-25 hours;
s13, putting the dried expanded graphite mixture powder into a cold mould pressing die for pressing and forming treatment, wherein the diameter of the die is 50mm, the pressing pressure is set to be 8-10 Mpa, and the pressing time is 15-20 min, so that an expanded graphite pressing piece is obtained;
s14, sintering the expanded graphite pressing piece at 375-380 ℃ for 120-130 min, cutting the sintered piece into a square piece with the size of 20mm multiplied by 20mm, and using the square piece as an expanded graphite base pressing piece;
the acetylene black has higher conductivity, so that the conductivity of the matrix material is improved by adding the acetylene black into the matrix material, and the PTFE emulsion and active substances (expanded graphite and the acetylene black) are mixed and then dried, so that the active substance particles are wrapped by the PTFE in a net structure form and are mutually connected to achieve the purpose of adhesion. In the invention, the polytetrafluoroethylene emulsion is used as the binder to bond the expanded graphite together, which is beneficial to the compression molding of the expanded graphite.
S2, preparing the molybdenum disulfide/expanded graphite hydrogen evolution electrode:
the dosage of the raw materials is as follows: the mass ratio of the expanded graphite matrix tablet to the ammonium molybdate to the thiourea is 1: 0.618 ~ 2.472: 1.14-4.56, the addition amount of ammonium molybdate corresponding to each square centimeter of expanded graphite matrix tablet is 0.071 mmol-0.284 mmol,
s21, adding ammonium molybdate and thiourea into deionized water, magnetically stirring at room temperature to fully dissolve the ammonium molybdate and the thiourea to obtain a precursor solution, and controlling the addition amount of the ammonium molybdate corresponding to each square centimeter of expanded graphite matrix tablet to be 0.071 mmol-0.284 mmol so as to optimize the hydrogen evolution performance of the finally prepared electrode;
s22, placing the expanded graphite matrix tablet in an ethanol solution, performing ultrasonic treatment for 1-2 hours, and drying at the drying temperature of 90-95 ℃ for 10-15 min;
s23, adding a mixed solution of ammonium molybdate and thiourea into the dried expanded graphite substrate tablet, heating at 199-201 ℃ for 24 hours, cooling to room temperature, and directly loading molybdenum disulfide on the expanded graphite substrate tablet;
and S24, respectively cleaning the expanded graphite matrix tablet loaded with the molybdenum disulfide by using deionized water and absolute ethyl alcohol, and drying to obtain the molybdenum disulfide/expanded graphite hydrogen evolution electrode.
Preferably, the temperature is raised from room temperature to the sintering temperature of 375-380 ℃ at a rate of 1 ℃/min during the sintering in step S14.
Preferably, in the step S23, the temperature is increased from room temperature to 199-201 ℃ at a speed of 5 ℃/min.
Preferably, the ammonium molybdate is added in an amount of 0.142 millimoles per square centimeter of expanded graphite substrate pellet.
Example 1
Firstly, sequentially adding 1g of natural crystalline flake graphite, 0.45g of potassium permanganate and 0.12g of ammonium nitrate into a dry and clean beaker with the volume of 250mL at room temperature, then slowly adding 8mL of perchloric acid into the beaker, placing a magnetic rotor, sealing the beaker by using a sealing film, then placing the sealed beaker into a heat collection type constant-temperature heating magnetic stirrer, setting the water bath temperature to be 30 ℃, adjusting the rotating speed to be 200r/min, and stirring for 60 min; after the intercalation reaction is finished, immediately taking out the beaker, placing the beaker in a fume hood, opening a sealing film of the beaker, taking out the magnetic rotor by using clean tweezers after the mixture in the beaker is cooled to room temperature, and then washing the mixture for multiple times by using deionized water until the pH of washing water is about 7; then, carrying out suction filtration and dehydration on the washed mixture by using a circulating water vacuum pump, transferring the mixture intercepted on the filter paper into a clean culture dish, placing the culture dish into a drying box, and drying the culture dish for 12 hours at 70 ℃ to obtain expandable graphite; and opening a muffle furnace for preheating, heating to 950 ℃, weighing 1g of the prepared expandable graphite, placing the expandable graphite into a dry and clean quartz beaker with the volume of 250mL, placing the quartz beaker into the muffle furnace for waiting for 4-5 s, and taking out to finally prepare the expandable graphite.
S1, tabletting expanded graphite:
firstly weighing 1g of expanded graphite and 0.1g of acetylene black in a dry and clean beaker with the volume of 500mL, then measuring 150mL of absolute ethyl alcohol and slowly adding the absolute ethyl alcohol into the beaker, then placing the beaker on a magnetic stirrer, firstly stirring for 30min at room temperature, measuring 5mL of polytetrafluoroethylene solution with the mass fraction of 60%, slowly pouring the polytetrafluoroethylene solution into the mixed solution, and continuously stirring for 60min to fully mix the mixed solution; preheating a constant-temperature water bath kettle, heating to 90 ℃, then placing the mixed solution after stirring in the constant-temperature water bath kettle to volatilize absolute ethyl alcohol in the mixed solution, then pouring the expanded graphite mixture into a clean culture dish, and then placing the culture dish in a drying box for drying treatment, wherein the drying temperature and the drying time are 65 ℃ and 24 hours respectively; taking out the dried expanded graphite mixture powder, and putting the powder into a cold mould pressing mold for pressing and forming treatment, wherein the diameter of the mold is 50mm, the pressing pressure is set to be 8Mpa, and the pressing time is 15 min; after the completion of the pressing of the expanded graphite mixture powder, the pressing member having a diameter of 50mm and a thickness of 2mm was taken out from the cold press mold and placed in a muffle furnace for sintering. Firstly, the temperature of a muffle furnace is increased to 375 ℃ from the temperature in the furnace at the speed of 1 ℃/min, then the reaction is carried out for 120min at the temperature, finally, the muffle furnace is closed, the muffle furnace is naturally cooled to the room temperature, then, a sintered piece is taken out, and finally, the sintered piece is cut into small square pieces with the size of 20mm multiplied by 20mm, and the expanded graphite substrate tabletting is prepared.
S2 preparation of molybdenum disulfide/expanded graphite hydrogen evolution electrode
Firstly, 0.618g of ammonium molybdate and 1.14g of thiourea are weighed and added into a beaker filled with 35mL of deionized water, a dry and clean rotor is placed into the beaker, the beaker is sealed by a sealing film, then the beaker is placed on a magnetic stirrer, the rotating speed is set to be 200r/min, and the stirring is carried out for 60min at room temperature, so that the ammonium molybdate and the thiourea are completely dissolved in the deionized water; putting the expanded graphite matrix tablet into a container filled with absolute ethyl alcohol, then putting the container into an ultrasonic processor for ultrasonic treatment for 1-2 hours, taking the expanded graphite matrix tablet out after the ultrasonic treatment is finished, putting the expanded graphite matrix tablet into a clean culture dish, and then putting the culture dish into a drying oven for drying treatment, wherein the drying time is 10-15 min, and the drying temperature is 90 ℃; firstly placing the expanded graphite substrate tablet subjected to ultrasonic treatment and drying in a 25mL polytetrafluoroethylene lining, then adding 20mL of fully dissolved ammonium molybdate and thiourea mixed solution, finally placing the lining in a stainless steel reaction kettle, screwing a sealing cover, and then placing the stainless steel reaction kettle in a muffle furnace. Firstly, the temperature of a muffle furnace is increased to 200 ℃ from the temperature in the furnace at the speed of 5 ℃/min, then the reaction is carried out for 24 hours at the temperature, finally, the muffle furnace is closed,naturally cooling the stainless steel reaction kettle to room temperature, taking out the stainless steel reaction kettle from a muffle furnace, loosening a sealing cover of the reaction kettle, taking out the expanded graphite substrate tablet loaded with molybdenum disulfide in the reaction kettle, and cleaning the tablet with deionized water and absolute ethyl alcohol respectively; finally, the cleaned composite material is placed in a culture dish and is placed in a drying oven, and drying treatment is carried out for 24 hours at the temperature of 60 ℃, so that the molybdenum disulfide/expanded graphite hydrogen evolution electrode is obtained and is marked as MoS2/EG-1。
Example 2
Firstly, sequentially adding 1g of natural crystalline flake graphite, 0.45g of potassium permanganate and 0.12g of ammonium nitrate into a dry and clean beaker with the volume of 250mL at room temperature, then slowly adding 8mL of perchloric acid into the beaker, placing a magnetic rotor, sealing the beaker by using a sealing film, then placing the sealed beaker into a heat collection type constant-temperature heating magnetic stirrer, setting the water bath temperature to be 30 ℃, adjusting the rotating speed to be 200r/min, and stirring for 60 min; after the intercalation reaction is finished, immediately taking out the beaker, placing the beaker in a fume hood, opening a sealing film of the beaker, taking out the magnetic rotor by using clean tweezers after the mixture in the beaker is cooled to room temperature, and then washing the mixture for multiple times by using deionized water until the pH of washing water is about 7; then, carrying out suction filtration and dehydration on the washed mixture by using a circulating water vacuum pump, transferring the mixture intercepted on the filter paper into a clean culture dish, placing the culture dish into a drying box, and drying the culture dish for 12 hours at 70 ℃ to obtain expandable graphite; and opening a muffle furnace for preheating, heating to 950 ℃, weighing 1g of the prepared expandable graphite, placing the expandable graphite into a dry and clean quartz beaker with the volume of 250mL, placing the quartz beaker into the muffle furnace for waiting for 4-5 s, and taking out to finally prepare the expandable graphite.
S1, tabletting expanded graphite:
firstly weighing 1g of expanded graphite and 0.1g of acetylene black in a dry and clean beaker with the volume of 500mL, then measuring 150mL of absolute ethyl alcohol and slowly adding the absolute ethyl alcohol into the beaker, then placing the beaker on a magnetic stirrer, firstly stirring for 30min at room temperature, measuring 5mL of polytetrafluoroethylene solution with the mass fraction of 60%, slowly pouring the polytetrafluoroethylene solution into the mixed solution, and continuously stirring for 60min to fully mix the mixed solution; preheating a constant-temperature water bath kettle, heating to 90 ℃, then placing the mixed solution after stirring in the constant-temperature water bath kettle to volatilize absolute ethyl alcohol in the mixed solution, then pouring the expanded graphite mixture into a clean culture dish, and then placing the culture dish in a drying box for drying treatment, wherein the drying temperature and the drying time are 65 ℃ and 24 hours respectively; taking out the dried expanded graphite mixture powder, and putting the powder into a cold mould pressing mold for pressing and forming treatment, wherein the diameter of the mold is 50mm, the pressing pressure is set to be 8Mpa, and the pressing time is 15 min; after the completion of the pressing of the expanded graphite mixture powder, the pressing member having a diameter of 50mm and a thickness of 2mm was taken out from the cold press mold and placed in a muffle furnace for sintering. Firstly, the temperature of a muffle furnace is increased to 375 ℃ from the temperature in the furnace at the speed of 1 ℃/min, then the reaction is carried out for 120min at the temperature, finally, the muffle furnace is closed, the muffle furnace is naturally cooled to the room temperature, then, a sintered piece is taken out, and finally, the sintered piece is cut into small square pieces with the size of 20mm multiplied by 20mm, and the expanded graphite substrate tabletting is prepared.
S2 preparation of molybdenum disulfide/expanded graphite hydrogen evolution electrode
Firstly, weighing 1.236g of ammonium molybdate and 2.28g of thiourea, adding the ammonium molybdate and the thiourea into a beaker filled with 35mL of deionized water, putting a dry and clean rotor into the beaker, sealing the beaker by using a sealing film, then putting the beaker on a magnetic stirrer, setting the rotating speed to be 200r/min, and stirring at room temperature for 60min to completely dissolve the ammonium molybdate and the thiourea in the deionized water; putting the expanded graphite matrix tablet into a container filled with absolute ethyl alcohol, then putting the container into an ultrasonic processor for ultrasonic treatment for 1-2 hours, taking the expanded graphite matrix tablet out after the ultrasonic treatment is finished, putting the expanded graphite matrix tablet into a clean culture dish, and then putting the culture dish into a drying oven for drying treatment, wherein the drying time is 10-15 min, and the drying temperature is 90 ℃; firstly placing the expanded graphite substrate tablet subjected to ultrasonic treatment and drying in a 25mL polytetrafluoroethylene lining, then adding 20mL of fully dissolved ammonium molybdate and thiourea mixed solution, finally placing the lining in a stainless steel reaction kettle, screwing a sealing cover, and then placing the stainless steel reaction kettle in a muffle furnace. Firstly, the temperature of the muffle furnace is increased to 200 ℃ from the temperature in the furnace at the speed of 5 ℃/min, then the reaction is carried out for 24 hours at the temperature, and finally, the muffle furnace is closed to be naturally cooledTaking out the stainless steel reaction kettle from the muffle furnace after the temperature is reached to room temperature, loosening a sealing cover of the reaction kettle, taking out the expanded graphite substrate tablet loaded with molybdenum disulfide in the reaction kettle, and cleaning the tablet with deionized water and absolute ethyl alcohol respectively; finally, the cleaned composite material is placed in a culture dish and is placed in a drying oven, and drying treatment is carried out for 24 hours at the temperature of 60 ℃, so that the molybdenum disulfide/expanded graphite hydrogen evolution electrode is obtained and is marked as MoS2/EG-2。
Example 3
Firstly, sequentially adding 1g of natural crystalline flake graphite, 0.45g of potassium permanganate and 0.12g of ammonium nitrate into a dry and clean beaker with the volume of 250mL at room temperature, then slowly adding 8mL of perchloric acid into the beaker, placing a magnetic rotor, sealing the beaker by using a sealing film, then placing the sealed beaker into a heat collection type constant-temperature heating magnetic stirrer, setting the water bath temperature to be 30 ℃, adjusting the rotating speed to be 200r/min, and stirring for 60 min; after the intercalation reaction is finished, immediately taking out the beaker, placing the beaker in a fume hood, opening a sealing film of the beaker, taking out the magnetic rotor by using clean tweezers after the mixture in the beaker is cooled to room temperature, and then washing the mixture for multiple times by using deionized water until the pH of washing water is about 7; then, carrying out suction filtration and dehydration on the washed mixture by using a circulating water vacuum pump, transferring the mixture intercepted on the filter paper into a clean culture dish, placing the culture dish into a drying box, and drying the culture dish for 12 hours at 70 ℃ to obtain expandable graphite; and opening a muffle furnace for preheating, heating to 950 ℃, weighing 1g of the prepared expandable graphite, placing the expandable graphite into a dry and clean quartz beaker with the volume of 250mL, placing the quartz beaker into the muffle furnace for waiting for 4-5 s, and taking out to finally prepare the expandable graphite.
S1, tabletting expanded graphite:
firstly weighing 1g of expanded graphite and 0.1g of acetylene black in a dry and clean beaker with the volume of 500mL, then measuring 150mL of absolute ethyl alcohol and slowly adding the absolute ethyl alcohol into the beaker, then placing the beaker on a magnetic stirrer, firstly stirring for 30min at room temperature, measuring 5mL of polytetrafluoroethylene solution with the mass fraction of 60%, slowly pouring the polytetrafluoroethylene solution into the mixed solution, and continuously stirring for 60min to fully mix the mixed solution; preheating a constant-temperature water bath kettle, heating to 90 ℃, then placing the mixed solution after stirring in the constant-temperature water bath kettle to volatilize absolute ethyl alcohol in the mixed solution, then pouring the expanded graphite mixture into a clean culture dish, and then placing the culture dish in a drying box for drying treatment, wherein the drying temperature and the drying time are 65 ℃ and 24 hours respectively; taking out the dried expanded graphite mixture powder, and putting the powder into a cold mould pressing mold for pressing and forming treatment, wherein the diameter of the mold is 50mm, the pressing pressure is set to be 8Mpa, and the pressing time is 15 min; after the completion of the pressing of the expanded graphite mixture powder, the pressing member having a diameter of 50mm and a thickness of 2mm was taken out from the cold press mold and placed in a muffle furnace for sintering. Firstly, the temperature of a muffle furnace is increased to 375 ℃ from the temperature in the furnace at the speed of 1 ℃/min, then the reaction is carried out for 120min at the temperature, finally, the muffle furnace is closed, the muffle furnace is naturally cooled to the room temperature, then, a sintered piece is taken out, and finally, the sintered piece is cut into small square pieces with the size of 20mm multiplied by 20mm, and the expanded graphite substrate tabletting is prepared.
S2 preparation of molybdenum disulfide/expanded graphite hydrogen evolution electrode
Firstly, weighing 2.472g of ammonium molybdate and 4.56g of thiourea, adding the ammonium molybdate and the thiourea into a beaker filled with 35mL of deionized water, putting a dry and clean rotor into the beaker, sealing the beaker by using a sealing film, then putting the beaker on a magnetic stirrer, setting the rotating speed to be 200r/min, and stirring at room temperature for 60min to completely dissolve the ammonium molybdate and the thiourea in the deionized water; putting the expanded graphite matrix tablet into a container filled with absolute ethyl alcohol, then putting the container into an ultrasonic processor for ultrasonic treatment for 1-2 hours, taking the expanded graphite matrix tablet out after the ultrasonic treatment is finished, putting the expanded graphite matrix tablet into a clean culture dish, and then putting the culture dish into a drying oven for drying treatment, wherein the drying time is 10-15 min, and the drying temperature is 90 ℃; firstly placing the expanded graphite substrate tablet subjected to ultrasonic treatment and drying in a 25mL polytetrafluoroethylene lining, then adding 20mL of fully dissolved ammonium molybdate and thiourea mixed solution, finally placing the lining in a stainless steel reaction kettle, screwing a sealing cover, and then placing the stainless steel reaction kettle in a muffle furnace. Firstly, the temperature of a muffle furnace is increased to 200 ℃ from the temperature in the furnace at the speed of 5 ℃/min, then the reaction is carried out for 24 hours at the temperature, and finally, the muffle furnace is closed, and the muffle furnace is naturally cooled to the room temperature and then is not usedTaking out the stainless steel reaction kettle from the muffle furnace, loosening a sealing cover of the reaction kettle, taking out the expanded graphite substrate tablet loaded with molybdenum disulfide in the reaction kettle, and cleaning the tablet with deionized water and absolute ethyl alcohol respectively; finally, the cleaned composite material is placed in a culture dish and is placed in a drying oven, and drying treatment is carried out for 24 hours at the temperature of 60 ℃, so that the molybdenum disulfide/expanded graphite hydrogen evolution electrode is obtained and is marked as MoS2/EG-3。
The electro-catalysis hydrogen evolution performance of the molybdenum disulfide/expanded graphite hydrogen evolution electrode is tested by adopting a three-electrode system, a platinum electrode is taken as a counter electrode, a saturated silver chloride electrode is taken as a reference electrode, the molybdenum disulfide/expanded graphite hydrogen evolution electrode is taken as a working electrode, a testing instrument is a Shanghai Chenghua CHI650C type electrochemical workstation, a testing solution is a 0.5mol/L sulfuric acid solution, and the testing result is shown in a figure 1a and a figure 1 b; from FIG. 1a, it can be seen that at a current density of 10mA cm-2When, MoS2/EG-1、MoS2[ EG-2 ] and MoS ]2The overpotential of the/EG-3 hydrogen evolution electrode reaches 280mV, 230mV and 270mV respectively, and the comparison shows that MoS2The overpotential for hydrogen evolution of the/EG-2 composite material is the minimum, so that the performance of hydrogen evolution of the cathode of the composite material prepared in the example 2 is the best among three composite materials. MoS is shown in FIG. 1b2/EG-1、MoS2[ EG-2 ] and MoS ]2The Tafel slope of the/EG-3 composite material is 94mV dec-1、77mV·dec-1And 91mV dec-1,MoS2The Tafel slope of the/EG-2 composite was the smallest, further demonstrating that the composite made in example 2 has the best hydrogen evolution performance of the three composites.
Fig. 2 is an X-ray diffraction pattern of pure molybdenum disulfide, which has characteristic diffraction peaks corresponding to the (002), (100) and (110) crystal planes of molybdenum disulfide at diffraction angles 2 θ of 13.7 °, 32.3 ° and 57.2 °, respectively. In a map of the molybdenum disulfide/expanded graphite composite material, the characteristic diffraction peaks of the expanded graphite are 26.86 degrees and 54.84 degrees, except the diffraction peaks of the expanded graphite, the characteristic diffraction peaks of (002), (100) and (110) crystal faces of the molybdenum disulfide are also detected, and the molybdenum disulfide/expanded graphite composite material electrode is proved to be successfully prepared by the method.
It can be seen from figure 3b that the molybdenum disulphide is flower-like and that the active sites are located at the edges of the flower. And the figure c shows that the flower-shaped structure in the figure 3b also exists in the composite material prepared by the invention and is uniformly distributed on the expanded graphite matrix composite sheet, and the edge of the molybdenum disulfide sheet is exposed, thereby proving that the molybdenum disulfide/expanded graphite composite material electrode is successfully prepared by the invention.
In the prior art, the molybdenum disulfide/expanded graphite composite material electrode prepared by the invention has the best hydrogen evolution performance when the current density is 10mA/cm2In the process, the overpotential can reach 230mV, and compared with the molybdenum disulfide electrode in the prior art, the hydrogen evolution performance is improved by 23%. Therefore, the composite material electrode prepared by the method has obviously improved hydrogen evolution performance, is not influenced by the pH of the electrolyte, and can electrolyze water to produce hydrogen in acid and alkali environments.
Finally, it should be noted that: the above-mentioned embodiments are only used for illustrating the technical solution of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.