Synergistic coupling vertical orientation Ru / Co co-doped MoS2 and interface wettability regulated electrocatalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of electro-catalytic materials, and discloses a preparation method of a ruthenium-cobalt double-metal doped molybdenum disulfide hydrogen evolution electro-catalytic material, which comprises the following steps: preparing an ionic liquid, and carrying out hydrophilic modification on carbon cloth by using the ionic liquid; preparing Co-doped MoS2 loaded on the modified carbon cloth by a one-pot method; carrying out high-temperature annealing on the Co-MoS2 / MCC in a tubular furnace to obtain a catalyst rich in Mo vacancy; ru is introduced into the Co-MoS2 / MCC by adopting a reduction bonding technology, and finally the cobalt-ruthenium double-doped CoRu-MoS2 / MCC is obtained. According to the preparation method, ionic liquid hydrophilic modification is carried out on carbon cloth, Co-doped MoS2 is loaded, a catalyst rich in Mo vacancy is prepared through high-temperature annealing, Ru is doped into the catalyst through a reduction bonding technology, the cobalt-ruthenium double-doped MoS2 composite material is formed, the layered structure advantage of MoS2 is combined with the high electrocatalytic activity of Co and Ru, and the preparation method is simple and easy to implement. Therefore, the hydrogen evolution electro-catalysis performance of the material is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrocatalytic materials, and particularly relates to preparation and application of a bimetallic co-doped molybdenum disulfide nanocomposite. BACKGROUND

[0002] In recent years, the overconsumption of fossil fuels and the exposure of environmental pollution problems have made people urgently seek green renewable energy. Hydrogen energy (H2) as a high-efficiency clean and environmentally friendly energy has entered the public's field of vision. Water electrolysis hydrogen production (HER) is a sustainable hydrogen production technology, which uses green renewable energy such as solar energy to drive water electrolysis hydrogen production, so that green renewable energy is stored in the form of hydrogen energy, which is a key path to realize continuous use of energy. Therefore, it is necessary to find a catalyst with a lower overpotential to reduce the kinetic energy barrier of the electrode reaction, thereby improving the efficiency of hydrogen production. At present, among a large number of developed water electrolysis hydrogen evolution catalysts, platinum-based noble metals are considered to be excellent catalysts for hydrogen evolution reaction, but due to their high price and limited storage, their large-scale application is limited, so it is crucial to develop a catalyst with high activity, low price and abundant storage.

[0003] Molybdenum disulfide (MoS2) in two-dimensional transition metal sulfide (TMDs) has been discovered due to its unique structure, abundant storage and high-density active edge, and has been applied to water electrolysis hydrogen production, and is considered to be one of the ideal materials that can replace platinum-based noble metals. Due to the inert basal plane and poor conductivity of MoS2, the improvement of catalytic performance is limited, so in order to improve the catalytic activity of MoS2, people try to use techniques such as heteroatom doping, phase transformation, amorphization, defect engineering and construction of heterostructure to enhance the HER activity. Heteroatom doping is a method of introducing other atoms in the preparation of catalysts, which not only activates the inert basal plane of MoS2, but also introduces other metal atoms into the MoS2 lattice, thereby affecting and regulating the electronic structure of the catalyst. In the current research, the methods of heteroatom doping MoS2 include impregnation method, electrochemical deposition method and ion implantation method, but these methods also have disadvantages. Among them, the impregnation method has limited loading capacity of doped heteroatoms, and it is difficult to introduce doped atoms into the catalyst in a short time, and the catalyst may fall off from the surface of the carrier during the electrochemical test, affecting the hydrogen evolution effect. When ion implantation is used for doping, lattice damage is inevitable in the energy loss process after ion implantation into the catalyst, and the ion implantation equipment is complex and expensive, and the production efficiency is low, which is not suitable for large-scale application. The electrochemical deposition method may produce uneven deposition products and poor adhesion due to the fact that the doped atoms are not grown in situ on the catalyst substrate, resulting in poor cycle life.

[0004] Generally, in-situ growth of MoS2 on carbon cloth can effectively improve the conductivity of the catalyst and expose more active sites, and carbon cloth as a composite material is more convenient during the process of testing the performance of electrocatalytic hydrogen evolution, but if the carbon cloth is not pretreated, the carbon cloth is in a hydrophobic state to grow the catalyst in-situ, which may cause uneven loading and active metal peeling. By using the interface engineering strategy to regulate the wettability of the carbon cloth surface, the catalyst precursor solution can be uniformly spread on the substrate surface, thereby promoting the full contact and uniform nucleation of Co, Ru metal ions and carbon cloth, significantly improving the dispersion and binding stability of doped atoms, avoiding catalyst shedding during the reaction, and prolonging the service life of the cycle; in addition, after the modification of the carbon cloth, the wettability gradient constructed on the surface of the carbon cloth can make the electrolyte quickly penetrate into the catalyst surface and the pores of the carbon cloth, reduce the mass transfer resistance of the "liquid-solid" interface, promote the rapid arrival of H + , H2O and other reaction substrates to the active site, while accelerating the desorption of product H2, reducing the hindering of bubble retention on the mass transfer process of the reaction system, and optimizing the mass transfer efficiency; the wettability regulation of the carbon cloth surface can also optimize the interface electron transfer: the improved wettability can enhance the interface compatibility of the catalyst with the carbon cloth and the electrolyte, reduce the charge transfer resistance, make the electronic regulation advantage brought by CoRu double doping fully play a role, and accelerate the electron transfer in the HER reaction. Therefore, improving the wettability of the carbon cloth is an effective strategy to improve the HER catalytic performance of the CoRu double-doped catalyst. Although some studies have successfully obtained uniform nanosheet / carbon cloth composites, the process of treating the carbon cloth is quite cumbersome, and the inherent structure of the carbon cloth is inevitably damaged in the process, which may affect its final performance in practical applications. SUMMARY

[0005] To solve the above technical problems, the main purpose of the present application is to provide an electrocatalytic hydrogen evolution catalyst and its preparation method and application, which can realize the directional growth of Ru / Co co-doped MoS2 vertically oriented on the surface of carbon cloth and the synergistic coupling of interface wettability regulation.

[0006] The present application provides a preparation method of an electrocatalytic material.

[0007] A preparation method of an electrocatalytic material, comprising the following steps:

[0008] Step 1, first prepare an imidazole-based ionic liquid, then ultrasonically clean the carbon cloth with acetone, ethanol and deionized water in sequence to remove surface impurities, and then soak the carbon cloth in the imidazole-based ionic liquid for surface modification. After soaking, take out the carbon cloth, dry and calcine to obtain a super-hydrophilic modified carbon cloth;

[0009] Step 2, mixing the molybdenum source, sulfur source, cobalt source, carbon source and water, stirring to form a uniform precursor solution, and adjusting the pH to 2-5 with hydrochloric acid; then placing the modified carbon cloth substrate obtained in step 1 in the precursor solution, reacting in a high-pressure reaction kettle at 160-200 ℃ for 10-15 h, washing and drying after the reaction is completed, to obtain a cobalt-doped molybdenum disulfide / modified carbon cloth precursor;

[0010] Step 3, heat-treating the cobalt-doped molybdenum disulfide / modified carbon cloth precursor obtained in step 2 in a reducing atmosphere at 280-350 ℃ for 5-20 min, to obtain a cobalt-doped molybdenum disulfide / modified carbon cloth material rich in molybdenum vacancies;

[0011] Step 4, immersing the cobalt-doped molybdenum disulfide / modified carbon cloth material rich in molybdenum vacancies obtained in step 3 in a ruthenium salt solution for 8-12 h, then drying, and heat-treating in a reducing atmosphere (5-15% H2 / 95-85% Ar2) at 180-220 ℃ for 0.5-1.5 h, to obtain a ruthenium-cobalt dual-metal-doped molybdenum disulfide / modified carbon cloth composite material.

[0012] The preparation method of the electrocatalytic material, wherein the preparation method of the modified carbon cloth substrate in step 1 comprises: washing the carbon cloth with an organic solvent and water, then immersing in an ionic liquid, drying, and then calcining in a muffle furnace at 320-380 ℃ for 2-5 h;

[0013] Preferably, the ionic liquid is selected from any one or several of 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), 1-ethyl-3-methylimidazolium chloride ([Emim]Cl), 1-hexyl-3-methylimidazolium chloride ([Hmim]Cl), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4), 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6), 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF4), and more preferably 1-butyl-3-methylimidazolium chloride ([Bmim]Cl).

[0014] The preparation method of the electrocatalytic material, wherein the hydrothermal method in step 2 comprises: mixing a molybdenum source, a sulfur source, a cobalt source, a carbon source and a solvent to form a precursor solution, adjusting the pH to 2-5, and then immersing the modified carbon cloth substrate in the precursor solution and reacting at 160-200 ℃ for 10-15 h;

[0015] Preferably, the molybdenum source is selected from any one or several of ammonium molybdate tetrahydrate, sodium molybdate, ammonium tetrathiomolybdate and molybdenum oxide, and more preferably ammonium molybdate tetrahydrate;

[0016] The sulfur source is selected from any one or several of thiourea, thioacetamide, sodium sulfide, sodium thiosulfate;

[0017] The cobalt source is selected from any one or several of cobalt chloride, cobalt carbonate, cobalt acetate, cobalt nitrate, cobalt sulfate;

[0018] The carbon source is selected from at least one of N,N-dimethylformamide, ascorbic acid, glucose, citric acid;

[0019] The solvent includes water and ethylene glycol in a volume ratio of 1: (0.5-2).

[0020] The preparation method of the electrocatalytic material, wherein the preparation of the imidazole-based ionic liquid required for the modified carbon cloth in step 1 comprises the following steps:

[0021] The 1-alkyl imidazole is reacted with a haloalkane at 60-90 DEG C for 6-15 h to obtain a halogenated 1-alkyl-3-methyl imidazole salt intermediate; the intermediate is subjected to an ion exchange reaction with a salt containing a target anion, and after the reaction is completed, the ionic liquid containing the target anion is obtained by washing with ethyl acetate and rotary evaporation to dryness.

[0022] The preparation method of the electrocatalytic material, wherein the preparation method of the modified carbon cloth substrate in step 1 is as follows: the carbon cloth (CC, 1 cm x 1.5 cm) is ultrasonically washed with acetone, ethanol and water for 15-30 min to remove surface impurities, then the carbon cloth (CC) is soaked in [Bmim]Cl for 10-15 h, dried at 50-80 DEG C for 5-8 h, then placed in a tube furnace and calcined at 320-380 DEG C for 2-5 h to obtain a super-hydrophilic modified carbon cloth.

[0023] The preparation method of the electrocatalytic material, wherein the specific operation of the hydrothermal method in step 2 is as follows: a molybdenum source (0.3-0.5 mmol) and a sulfur source (10-15 mmol) are sequentially added to 20-30 mL of water, stirred until dissolved, then 0.2-0.5 g of N,N-dimethylformamide, 0.05-0.25 g of ascorbic acid and 0.02-0.06 g of glucose are sequentially added, the mixture is stirred until completely dissolved, then 15-35 mL of ethylene glycol is added and stirred uniformly, 0.5-0.8 mL of hydrochloric acid is added to adjust the pH to 2-5, and finally 0.1-0.3 mmol of a cobalt source is added. After stirring for 15-30 min, the obtained mixture is transferred into a stainless steel autoclave with a polytetrafluoroethylene liner, and the hydrophilic modified carbon cloth is placed in the reaction kettle, and the temperature is kept at 160-200 DEG C for 10-15 h. After hydrothermal treatment, the carbon cloth loaded with active metals is washed with ethanol and water three times each, and then vacuum dried at 50-80 DEG C for 5-8 h to obtain a cobalt-doped molybdenum disulfide / modified carbon cloth precursor.

[0024] The preparation method of the electrocatalytic material, wherein in step 3, the molybdenum disulfide / modified carbon cloth precursor is placed in a tube furnace, and a surface Mo vacancy-rich cobalt-doped molybdenum disulfide / modified carbon cloth material is obtained by annealing at 280-350 DEG C for 2-7 min under a 5-15% H2 / 95-85% Ar2 atmosphere.

[0025] The preparation method of the electrocatalytic material, wherein in step 4, the method for ruthenium doping is as follows: after the Mo vacancy-rich cobalt-doped molybdenum disulfide / modified carbon cloth material is cooled to room temperature, it is soaked in a 0.01-0.05 M ruthenium salt solution for 8-12 h to fully adsorb active metal ruthenium, and then dried at 50-80 DEG C for 5-8 h, and then placed in a tube furnace, and a ruthenium cobalt double-metal-doped molybdenum disulfide / modified carbon cloth composite material is obtained by reduction at 180-220 DEG C for 0.5-1.5 h under a 5-15% H2 / 95-85% Ar2 atmosphere.

[0026] In order to achieve the above purpose, the application further provides an electrocatalytic material catalyst obtained by the above-mentioned preparation method of the electrocatalytic material.

[0027] In order to achieve the above purpose, the application further provides an application of the above-mentioned electrocatalytic material catalyst in electrocatalytic hydrogen evolution.

[0028] The application has the following beneficial effects:

[0029] 1. The application fully soaks the carbon cloth in [Bmim]Cl, and then calcines to form nitrogen-containing carbon species on the surface of the carbon cloth, thereby changing the electronic distribution of the carbon cloth, improving the conductivity and wettability of the carbon cloth, and providing nucleation sites for MoS2 nanosheets.

[0030] 2. The application uses a hydrothermal method to vertically grow Co-MoS2 nanosheets on the modified carbon cloth, exposes more effective areas, thereby significantly increasing the number of active sites, and improving the HER catalytic activity and durability of the catalyst.

[0031] 3. The application uses annealing etching to treat the catalyst, not only introduces an appropriate amount of defects on the inert basal plane of MoS2, but also effectively activates adjacent S atoms by substituting Mo vacancies with Ru atoms, further activates the inert basal plane, and the Ru atom and Co atom co-doped catalyst exhibits excellent catalytic activity for HER in an acidic electrolyte. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The flowchart of the ruthenium cobalt double-metal-doped molybdenum disulfide hydrogen evolution electrocatalytic material.

[0033] Figure 2(a), 2(b) and 2(c), 2(d) are SEM and HRTEM images of RuCo-MoS2 / MCC catalyst prepared in Example 1, respectively.

[0034] Figure 3 HRTEM image of RuCo-MoS2 / CC@OP catalyst prepared in Comparative Example 1.

[0035] Figure 4 (a) and 4(b) are static water contact angles of CC before modification and carbon cloth after modification, respectively, Figure 4 (c) and 4(d) are static water contact angles of catalyst RuCo-MoS2 / CC in Comparative Example 2 and catalyst RuCo-MoS2 / MCC in Example 1, respectively.

[0036] Figure 5 XPS high-resolution deconvolution spectrum of Mo 3d and S 2p orbitals of RuCo bimetallic doped MoS2 hydrogen evolution electrocatalytic material.

[0037] Figure 6 (a) polarization curve, (b) Tafel curve, (c) linear fitting diagram of current density difference and scanning rate, (d) TOF value and (e) Nyquist diagram of RuCo-MoS2 / MCC, and (f) i-t stability test of RuCo-MoS2 / MCC. DETAILED DESCRIPTION

[0038] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present application, the technical solutions of the present application will be described in detail as follows, but it should not be understood as limiting the scope of the present application. In the examples, each raw reagent material can be commercially available unless otherwise specified, and the experimental method without specific conditions is a conventional method and conventional condition well known in the art, or according to the conditions recommended by the instrument manufacturer.

[0039] The present application provides a preparation method of an electrocatalytic material, comprising the following steps:

[0040] Step 1, hydrophilic modification of carbon cloth with ionic liquid to obtain MCC.

[0041] Step 2, one-pot preparation of Co-doped MoS2 loaded on modified carbon cloth to obtain Co-MoS2 / MCC.

[0042] Step 3, high-temperature annealing of Co-MoS2 / MCC in a tube furnace to obtain a catalyst Co-MoS2(V Mo ) / MCC rich in Mo vacancies.

[0043] Step 4, impregnation of Co-MoS2(VMo ) / MCC is put into RuCl3 and mixed thoroughly, and then calcination is performed to obtain a cobalt-ruthenium double-doped MoS2.

[0044] The present application first prepares an ionic liquid, and then the carbon cloth is soaked in the ionic liquid and calcined, which helps to promote the formation of nitrogen-containing carbon species and oxygen-containing functional groups on the surface of the carbon cloth, thereby improving the wettability of the carbon cloth and enhancing the conductivity thereof.

[0045] In an embodiment, the molybdenum source added in step 2 is ammonium molybdate tetrahydrate, the sulfur source is thiourea, and the cobalt source is cobalt chloride. In an embodiment, the molybdenum source and the sulfur source are first dissolved in water, then ethylene glycol is added, and then the cobalt source is dissolved. The molar ratio of the molybdenum source (calculated as molybdenum) to the sulfur source (calculated as sulfur) is 1:2-3.

[0046] In an embodiment, the specific treatment steps for the carbon cloth are as follows: the carbon cloth is cleaned with acetone, ethanol and water, and then is soaked in an ionic liquid, dried and calcined in a muffle furnace to obtain a hydrophilic modified carbon cloth MCC.

[0047] In an embodiment, the preparation method of the ionic liquid is as follows: 1-methylimidazole and chloro-n-butane are sequentially added to a round-bottom flask, heated, for example, to 50-70 ℃ for reaction, washed with ethyl acetate after the reaction is completed, and evaporated to dryness to obtain a clear viscous ionic liquid.

[0048] In an embodiment, the reaction is a hydrothermal deposition reaction, which is carried out in a closed container, for example, in an autoclave, and more specifically, in a stainless steel reaction kettle with a polytetrafluoroethylene lining. The reaction temperature is 160-200 ℃, and the reaction time is 10-15 h. In another embodiment, the hydrothermal deposition reaction is carried out under dynamic conditions, for example, by placing the reaction kettle in a rotating constant-temperature oven, so that the multi-gold MoS2 is deposited on the MCC under dynamic conditions.

[0049] In an embodiment, step 3 is to further sulfurize the MoS2 vertically grown on the modified carbon cloth in a tube furnace to obtain a catalyst rich in Mo vacancies.

[0050] In this step, the gas passed through the tube furnace is a mixture of 5-15% H2 / 95-85% Ar2, and the annealing temperature is 280-350 ℃.

[0051] In this step, Co-MoS2 nanosheets are vertically grown on the modified carbon cloth, which exposes more effective areas, thereby significantly increasing the number of active sites. At the same time, the doping of Co atoms adjusts the electronic structure of MoS2, enriches the edge active sites of MoS2, and thus improves the HER catalytic activity of the catalyst.

[0052] In an embodiment, the impregnated solution is a RuCl3 solution, the impregnation time is 10-15 h, and the Co-MoS2(V Mo ) / MCC is dried first and then calcined after impregnation.

[0053] In this step, the catalyst is treated by means of annealing etching, which not only introduces appropriate defects in the inert basal plane of MoS2, but also effectively activates the adjacent S atoms by substituting Mo vacancies with Ru atoms, further activates the inert basal plane, generates new active sites, and thus accelerates the hydrogen evolution catalytic process.

[0054] The electrocatalytic material catalyst obtained by the above method has high metal dispersion, appropriate MoS2 stacking layer number, and high hydrogen evolution activity, and can realize efficient electrocatalytic hydrogen evolution.

[0055] The technical solutions of the present application will be further described in detail below through specific examples.

[0056] Example 1

[0057] The present embodiment provides a preparation method of an electrocatalytic material, which comprises the following steps:

[0058] Step one, 8.21 g of 1-methylimidazole and 16.45 g of n-chlorobutane are sequentially added to a round-bottom flask, and stirred under reflux at 70℃ for 12 h;

[0059] Step two, the product after the reaction in step one is eluted with ethyl acetate to remove unreacted 1-methylimidazole and residual n-chlorobutane and other organic impurities, and is evaporated to dryness at 60℃ to obtain a clear viscous liquid 1-butyl-3-methylimidazolium chloride [Bmim]Cl;

[0060] Step three, the carbon cloth is ultrasonically washed with acetone, ethanol and water for 10 min to remove surface impurities, and then the carbon cloth is soaked in [Bmim]Cl for 10 h and dried at 60℃;

[0061] Step four, the sample obtained in step three is calcined in a muffle furnace at 320℃ for 6 h, and in the heat treatment process, the nitrogen-containing organic component is gradually decomposed and coupled with the carbon cloth skeleton, and the nitrogen-containing carbon species and oxygen-containing functional groups are formed on the surface of the carbon cloth, which significantly improves the polarity and surface energy of the carbon cloth surface to obtain a hydrophilic modified carbon cloth MCC;

[0062] Step five, 0.52 g of ammonium molybdate tetrahydrate and 0.82 g of thiourea are sequentially added to a beaker containing 20 mL of deionized water, and placed on a magnetic stirrer for stirring at room temperature until a homogeneous solution is obtained;

[0063] Step six, 0.2 g of N,N-2 methyl formamide, 0.05 g of ascorbic acid and 0.02 g of glucose were sequentially added to the homogeneous solution obtained in step four, and the mixture was continuously stirred on a magnetic stirrer. After complete dissolution, 15 mL of ethylene glycol was added and stirred uniformly, and hydrochloric acid was added to adjust the pH to 2. Finally, 0.058 g of cobalt chloride was added and stirred thoroughly;

[0064] Step seven, the mixture obtained in step five was transferred into a stainless steel autoclave with a polytetrafluoroethylene liner, and the modified carbon cloth obtained in step three was also placed in the autoclave. The reaction autoclave was placed in a rotating oven at 160 °C for 10 h. After the reaction was completed, it was cooled to room temperature;

[0065] Step eight, the sample obtained in step seven was taken out of the reaction autoclave, and washed with deionized water and anhydrous ethanol, and then dried at 60 °C for 6 h. After drying, Co-MoS2 / MCC was obtained;

[0066] Step nine, Co-MoS2 / MCC was placed in a tube furnace and annealed at 280 °C for 5 min under a 5% H2 / 95% Ar2 atmosphere to obtain Co-MoS2(V Mo ) / MCC with Mo vacancies on the surface;

[0067] Step ten, after cooling to room temperature, Co-MoS2(V Mo ) / MCC was immersed in a 0.01 M RuCl3 solution for 8 h to allow it to adsorb active metal Ru. It was then dried at 60 °C for 6 h;

[0068] Step eleven, Co-MoS2(V Mo ) / MCC adsorbed with metal Ru obtained in step eight was placed in a tube furnace and reduced at 180 °C for 0.5 h under a 5% H2 / 95% Ar2 atmosphere to obtain bimetallic doped RuCo-MoS2 / MCC.

[0069] Example 2

[0070] The present embodiment provides a method for preparing an electrocatalytic material, which comprises the following steps:

[0071] Step one, 8.21 g of 1-methylimidazole and 50 mL of anhydrous acetonitrile were sequentially added to a round-bottom flask, followed by the slow dropwise addition of 13.44 g of bromoethane. The mixture was stirred and refluxed at 70 °C for 12 h;

[0072] Step two, the product after the reaction in step one was eluted with ethyl acetate to remove unreacted 1-methylimidazole and other organic impurities, and then evaporated to dryness at 60 °C to obtain 1-ethyl-3-methylimidazolium tetrafluoroborate [Emim]Br;

[0073] Step three, the carbon cloth was washed with acetone, ethanol and water respectively for 15 min to remove the surface impurities, then the carbon cloth was immersed in [Bmim]Cl for 11 h and dried at 60 ℃;

[0074] Step four, the sample obtained in step three was placed in a muffle furnace and calcined at 330 ℃ for 3 h to promote the formation of nitrogen-containing carbon species and oxygen-containing functional groups on the surface of the carbon cloth, significantly increasing the surface polarity and surface energy of the carbon cloth to obtain a hydrophilic modified carbon cloth MCC;

[0075] Step five, 0.52 g of sodium molybdate and 0.82 g of thioacetamide were sequentially added to a beaker containing 20 mL of deionized water, and placed on a magnetic stirrer for stirring at room temperature until a homogeneous solution was obtained.

[0076] Step six, 0.3 g of N,N-2-methylformamide, 0.1 g of ascorbic acid and 0.03 g of glucose were sequentially added to the homogeneous solution obtained in step four, and placed on a magnetic stirrer for continuous stirring. After complete dissolution, 20 mL of ethylene glycol was added and stirred uniformly, and hydrochloric acid was added to adjust the pH to 3. Finally, 0.058 g of cobalt chloride was added and stirred thoroughly.

[0077] Step seven, the mixture obtained in step five was transferred into a polytetrafluoroethylene-lined stainless steel autoclave, and the modified carbon cloth obtained in step three was also placed in the autoclave. The reaction kettle was placed in a rotating oven at 170 ℃ for 11 h. After the reaction was completed, it was cooled to room temperature;

[0078] Step eight, the sample obtained in step seven was taken out of the reaction kettle, first washed with deionized water and anhydrous ethanol, and dried at 60 ℃ for 6 h. After drying, Co-MoS2 / MCC was obtained.

[0079] Step nine, Co-MoS2 / MCC was placed in a tube furnace and annealed at 290 ℃ for 10 min under a 10% H2 / 90% Ar2 atmosphere to obtain a Co-MoS2 / MCC catalyst.

[0080] Comparative Example 1

[0081] The present embodiment provides a method for preparing an electrocatalytic material, which comprises the following steps:

[0082] In the preparation of Co-MoS2 / MCC (the Co-doped molybdenum sulfide is Co-MoS2 / MCC prepared in Example 1), 1.0 mL of 0.05 M RuCl3 solution was added, stirred for half an hour, and then transferred to a polytetrafluoroethylene-lined stainless steel autoclave. It was kept at 180 ℃ for 12 h to synthesize RuCo-MoS2 / CC@OP by one-pot method.

[0083] Comparative Example 2

[0084] The present example provides a method for preparing an electrocatalytic material, which comprises the following steps:

[0085] The modified carbon cloth prepared in Example 1 was replaced with unmodified carbon cloth, and the obtained mixture and the modified carbon cloth were transferred into a stainless steel autoclave lined with polytetrafluoroethylene. The reaction kettle was placed in a 160°C rotary oven for reaction for 10 h. The carbon cloth loaded with active metal was washed with ethanol and water for three times each, and dried to obtain Co-MoS2 / CC. After high-temperature annealing at 290°C for 10 min under an atmosphere of 10% H2 / 90% Ar2, the Co-MoS2 / CC was immersed in a 0.02 M RuCl3 solution for 9 h to adsorb active metal Ru, and dried. The obtained product was then placed in a tube furnace for reduction at 190°C for 0.6 h under an atmosphere of 10% H2 / 90% Ar2, to obtain a bimetallic doped RuCo-MoS2 / CC.

[0086] Comparative Example 3

[0087] The present example provides a method for preparing an electrocatalytic material, which comprises the following steps:

[0088] First, 0.82 g of thiourea was dissolved in 50 mL of water, and then 0.52 g of ammonium molybdate tetrahydrate was added. After stirring for 80 min, the mixture was transferred into a stainless steel autoclave lined with polytetrafluoroethylene, and kept at a constant temperature of 180°C for 12 h. After cooling to room temperature, the product was washed several times with deionized water and ethanol, and dried at 60°C for 8 h to obtain bulk MoS2.

[0089] Comparative Example 4

[0090] The present example provides a method for preparing an electrocatalytic material, which comprises the following steps:

[0091] The mixture prepared in Example 1 without adding a cobalt source and the modified carbon cloth were transferred into a stainless steel autoclave lined with polytetrafluoroethylene, and the reaction kettle was placed in a 160°C rotary oven for reaction for 10 h. The carbon cloth loaded with active metal was washed with ethanol and water for three times each, and dried to obtain MoS2 / CC. After high-temperature annealing at 290°C for 10 min under an atmosphere of 10% H2 / 90% Ar2, the MoS2 / CC was obtained.

[0092] Test Example 1

[0093] All electrochemical measurements were performed on an electrochemical workstation using a three-electrode system, with a graphite rod as the counter electrode, Ag / AgCl / 3.5 M KCl as the reference electrode, and the electrode potential being 0.205 V. The electrochemical measurements were performed in an acidic solution (0.5 M H2SO4).

[0094] At a scan rate of 5 mV·s -1 Linear sweep voltammetry polarization curves were obtained at a scan potential range of -0.697~ -0.007 V (vs. Ag / AgCl) with 90% iR compensation. The Tafel slope was fitted by the equation η = blogj + a, where η represents the overpotential and j represents the current density. The reversible hydrogen electrode was tested at 20, 40, 60, 80, 100 mV·s -1 Cyclic voltammetry curves were tested at a scan rate of 5 mV·s 5 The electrochemical impedance was tested at a frequency range of 10 -2 The stability of the composite material was tested by continuously running for 5 h, and then the change in the LSV curve in the HER process was evaluated.

[0095] Figure 2 (a) and (b) are SEM images of the RuCo-MoS2 / MCC catalyst prepared in this embodiment 1, (c) and (d) are HRTEM images of the RuCo-MoS2 / MCC catalyst prepared in this embodiment 1. Figure 2 The SEM image of (a) shows that the catalyst is uniformly and densely distributed on the surface of the MCC carbon cloth without obvious agglomeration, which is conducive to the transmission of electrons and substances, Figure 2 (b) shows that it grows in a porous coral-like structure vertically on the MCC, providing a large specific surface area and promoting the exposure of active sites and gas desorption. Figure 2 The interlayer spacing of the MoS2 nanosheet is about 0.66 nm, which is significantly larger than the 0.62 nm of traditional 2H-MoS2. The interlayer spacing is expanded due to the insertion of gas between the layers generated by the thermal decomposition of DMF, which effectively inhibits the restacking of nanosheets and increases the exposure of edge active sites. Figure 2 In (d), the number of layers of the MoS2 nanosheet of the catalyst is observed to be less, which can fully expose the active sites, and the surface Mo vacancies are replaced by Ru atoms and the edge S vacancies are replaced by Co atoms, thereby further increasing the conductivity and active sites of the catalyst, so the electron transfer can be greatly enhanced, which is conducive to the electrocatalytic hydrogen evolution.

[0096] Figure 3HRTEM image of RuCo-MoS2 / CC@OP catalyst prepared for Comparative Example 1. It can be observed that most of the Ru species did not successfully dope into the MoS2 lattice, but rather exhibited a non-uniform distribution, indicating that under this preparation condition, Ru was difficult to precisely anchor at the Mo site vacancy, thus failing to form stable and effective chemical bonding with the MoS2 matrix. In contrast, the RuCo-MoS2 / MCC catalyst of Example 1 was able to effectively regulate the doping behavior of Ru, allowing Ru atoms to preferentially occupy Mo vacancies and form stable coordination structures, thereby significantly improving the structural integrity and intrinsic catalytic performance of MoS2.

[0097] Figure 4 (a) and 4(b) are the static water contact angles of carbon cloth before and after modification, respectively, Figure 4 (c) and 4(d) are the static water contact angles of Comparative Example 2 catalyst RuCo-MoS2 / CC and Example 1 catalyst RuCo-MoS2 / MCC, respectively. Figure 4 (a) shows that the water contact angle of the unmodified carbon cloth is 117.2°, exhibiting hydrophobic characteristics, indicating that the aqueous solution cannot wet the fabric surface and cannot enter the gap between the carbon fibers, which is not conducive to the growth of the catalyst. Figure 4 (b) is the water contact angle of the modified carbon cloth, which exhibits superhydrophilicity. The mechanism is that the modification process introduces polar oxygen-containing functional groups such as hydroxyl and carboxyl groups on the surface of the carbon cloth, greatly increasing the surface free energy of the substrate. When water droplets contact the modified carbon cloth, they will quickly spread and completely wet the gap between the carbon fibers, providing a uniform precursor distribution medium for subsequent catalyst growth. The RuCo-MoS2 / CC contact angle is 130.2° Figure 4 (c)), compared to the RuCo-MoS2 / MCC contact angle of 55.2° Figure 4 (d)), with a contact angle difference of 75°. This difference is due to the regulation of the substrate wettability on the growth behavior of the catalyst. The uneven distribution of precursors on the hydrophobic CC surface easily leads to catalyst particle agglomeration, making the composite sample still retain strong hydrophobicity; while the uniform precursor spreading on the hydrophilic MCC surface promotes the dispersion and growth of the catalyst, and the interaction between the polar groups of the substrate and the surface of the catalyst further optimizes the wettability of the composite system. Lower WCA helps the electrolyte to quickly spread and mass transfer on the surface of the catalyst, which has a positive significance for improving the electrocatalytic reaction kinetics.

[0098] Figure 5(a) and 5(b) show the high-resolution XPS deconvoluted spectra of Mo 3d and S 2p orbitals in the catalyst. Compared with pure MoS2 / MCC, the Mo 3d binding energy of Co-MoS2 / MCC shifts to low field by 0.13 eV, and the S 2p binding energy shifts to low field at the same time. This phenomenon is due to the substitution of Co atoms for Mo sites in the MoS2 lattice. Since the electronegativity of Co is lower than that of Mo, the Co atom will transfer electrons to the adjacent Mo and S atoms after entering the lattice, making the Co itself in a state of losing electrons, and the electron cloud density of Mo and S increases, corresponding to the decrease of binding energy, completing the charge rearrangement between Co and MoS2. Further comparison of the spectra of RuCo-MoS2 / MCC and Co-MoS2 / MCC shows that the Mo 3d and S 2p spectra of the former shift to low binding energy, indicating that Ru atoms are successfully doped into the Mo vacancies of MoS2. The electron transfer mechanism is that the electronegativity of Ru is close to that of Mo, but the lattice distortion of Mo vacancies changes the local electronic environment, causing Ru atoms to transfer electrons to the surrounding Mo and S atoms, i.e. Ru loses electrons, and Mo and S gain electrons.

[0099] Figure 6 (a) is the linear sweep voltammetry curve of the catalyst, and the overpotential of the prepared RuCo-MoS2 / MCC is 62 mV at a current density of 10 mA·cm -2 , which is significantly better than that of other catalysts. Figure 6 (b) shows that RuCo-MoS2 / MCC has a smaller Tafel slope of 48.2 mV·dec -1 , indicating that it has the fastest electrocatalytic hydrogen evolution reaction rate. Figure 6 (c) and 6(d) can be observed that the Co-MoS2 / MCC catalyst has the largest electrochemical active surface area (ECSA) and TOF value. The above phenomenon is due to the modification of carbon cloth before the preparation of RuCo-MoS2 / MCC catalyst. The soaking of [Bmim]Cl helps to introduce nitrogen-containing functional groups, which can form strong interaction with RuCo-MoS2 nanoparticles, further improving the dispersion and stability of the catalyst. And the modified carbon cloth as a self-supporting electrode has significantly improved wettability, which can make the electrolyte and catalyst fully contact, promote the transfer of electrons, and thus ensure that the carbon cloth loaded catalyst can expose more active sites and enhance the conductivity of the catalyst. On the other hand, in the preparation of RuCo-MoS2 / MCC, the Ru atom is doped into RuCo-MoS2 / MCC by reduction bonding technology, and the Ru atom grows in situ on the vertically grown MoS2 nanosheet and activates the inert basal plane of MoS2, which greatly improves the hydrogen evolution performance of the double-atom-doped RuCo-MoS2 / MCC. Figure 6(e) The RuCo-MoS2 / MCC resistance is the smallest during the hydrogen evolution reaction, and the catalyst loaded on carbon cloth as a self-supporting electrode shows smaller impedance than the powder electrode, indicating that the electrolyte and catalyst active sites can be in full contact, have faster charge transfer ability, and accelerate H + is converted into H2, therefore, the low impedance of RuCo-MoS2 / MCC is conducive to the progress of HER. The chronopotentiometric test of the RuCo-MoS2 / MCC catalyst was carried out for 300 min at a voltage of 62 mV overpotential, and the results are shown in Fig. 6. Figure 6 (f) As shown in Fig. 7, the performance almost does not attenuate, indicating that it has excellent electrocatalytic hydrogen evolution stability. This excellent stability is mainly due to the synergistic effect of Ru and Co, which enhances the electrical conductivity and mechanical strength of the material, and the structure of the vertically grown MoS2 nanosheet on the MCC also provides a good channel for electron transmission.

[0100] Of course, the protection scope of the present application is not limited to the above specific implementation forms. Those skilled in the art can make various adaptive modifications and extensions to the present application without departing from the inventive concept and technical principles of the present application, and all such modifications and extensions shall fall within the protection scope of the claims of the present application.

Claims

1. A synergistically coupled, vertically oriented Ru / Co co-doped MoS2 and an electrocatalyst with regulated interfacial wettability, and its preparation method thereof, characterized in that, Includes the following steps: Step 1: First, an imidazole-based ionic liquid is prepared. Then, the carbon cloth is ultrasonically cleaned sequentially with acetone, ethanol, and deionized water to remove surface impurities. Subsequently, the carbon cloth is immersed in the imidazole-based ionic liquid for surface modification. After immersion, the carbon cloth is removed, dried, and calcined to obtain the superhydrophilic modified carbon cloth. Step 2: Mix molybdenum source, sulfur source, cobalt source, carbon source and water, stir to form a homogeneous precursor solution, and adjust the pH to 2-5 with hydrochloric acid; then place the modified carbon cloth substrate obtained in Step 1 in the precursor solution, and react in a high-pressure reactor at 160-200℃ for 10-15 h. After the reaction is completed, wash and dry to obtain cobalt-doped molybdenum disulfide / modified carbon cloth precursor. Step 3: The cobalt-doped molybdenum disulfide / modified carbon cloth precursor obtained in Step 2 is heat-treated at 280~350℃ for 5~20 min in a reducing atmosphere to obtain cobalt-doped molybdenum disulfide / modified carbon cloth material rich in molybdenum vacancies. Step 4: The cobalt-doped molybdenum disulfide / modified carbon cloth material rich in molybdenum vacancies obtained in Step 3 is immersed in a ruthenium salt solution for 8-12 h, then dried, and then heat-treated at 180-220 °C for 0.5-1.5 h in a reducing atmosphere (5-15% H2 / 95-85% Ar2) to obtain the ruthenium-cobalt bimetallic doped molybdenum disulfide / modified carbon cloth composite material.

2. The preparation method according to claim 1, characterized in that, The preparation method of the modified carbon cloth substrate in step 1 includes: cleaning the carbon cloth with organic solvent and water, immersing it in an ionic liquid, drying it, and then calcining it in a muffle furnace at 320~380 ℃ for 2~5 h; Preferably, the ionic liquid is selected from one or more of 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), 1-ethyl-3-methylimidazolium chloride ([Emim]Cl), 1-hexyl-3-methylimidazolium chloride ([Hmim]Cl), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4), 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6), and 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF4), and more preferably 1-butyl-3-methylimidazolium chloride ([Bmim]Cl).

3. The preparation method according to claim 1, characterized in that, The hydrothermal method described in step 2 includes: mixing a molybdenum source, a sulfur source, a cobalt source, a carbon source, and a solvent to form a precursor solution, adjusting the pH to 2-5, and then immersing the modified carbon cloth substrate in the precursor solution and reacting at 160-200 °C for 10-15 h. Preferably, the molybdenum source is selected from any one or more of ammonium molybdate tetrahydrate, sodium molybdate, ammonium tetrathiomolybdate, and molybdenum oxide, and more preferably ammonium molybdate tetrahydrate; The sulfur source is selected from one or more of thiourea, thioacetamide, sodium sulfide, and sodium thiosulfate; The cobalt source is selected from any one or more of cobalt chloride, cobalt carbonate, cobalt acetate, cobalt nitrate, and cobalt sulfate; The carbon source is selected from at least one of N,N-dimethylformamide, ascorbic acid, glucose, and citric acid; The solvent comprises water and ethylene glycol in a volume ratio of 1:(0.5~2).

4. The preparation method according to claim 1, characterized in that, The preparation of the imidazole-based ionic liquid required for the modified carbon cloth in step 1 includes the following steps: 1-alkylimidazolium was reacted with haloalkanes at 60-90 °C for 6-15 h to obtain a halo-1-alkyl-3-methylimidazolium salt intermediate; the intermediate was then subjected to an ion exchange reaction with a salt containing the target anion, and after the reaction was completed, the solution was washed with ethyl acetate and evaporated to dryness to obtain an ionic liquid containing the target anion.

5. The preparation method according to claim 1, characterized in that, The modified carbon cloth substrate in step 1 is prepared as follows: carbon cloth (CC, 1 cm × 1.5 cm) is ultrasonically washed with acetone, ethanol and water for 15-30 min to remove surface impurities. Then, the carbon cloth (CC) is immersed in [Bmim]Cl for 10-15 h, dried at 50-80 ℃ for 5-8 h, and then calcined in a tube furnace at 320-380 ℃ for 2-5 h to obtain superhydrophilic modified carbon cloth.

6. The preparation method according to claim 1, characterized in that, The specific operation of the hydrothermal method in step 2 is as follows: Molybdenum source (0.3-0.5 mmol) and sulfur source (10-15 mmol) are added sequentially to 20-30 mL of water and stirred until dissolved. Then, 0.2-0.5 g of N,N-dimethylformamide, 0.05-0.25 g of ascorbic acid, and 0.02-0.06 g of glucose are added sequentially. After complete dissolution, 15-35 mL of ethylene glycol is added and stirred until homogeneous. 0.5-0.8 mL of hydrochloric acid is added to adjust the pH to 2-5. Finally, 0.1-0.3 mmol of cobalt source is added. After stirring for 15-30 min, the resulting mixture is transferred to a stainless steel autoclave lined with polytetrafluoroethylene. Simultaneously, hydrophilic modified carbon is arranged in the autoclave, and the mixture is kept at 160-200 °C for 10-15 h. After hydrothermal treatment, the carbon cloth carrying the active metal was washed three times each with ethanol and water, and then vacuum dried at 50-80 °C for 5-8 h to obtain the cobalt-doped molybdenum disulfide / modified carbon cloth precursor.

7. The preparation method according to claim 1, characterized in that, In step 3, the molybdenum disulfide / modified carbon cloth precursor is placed in a tube furnace and annealed at 280-350 °C for 2-7 min under an atmosphere of 5-15% H2 / 95-85% Ar2 to obtain a molybdenum disulfide / modified carbon cloth material with a surface rich in Mo vacancy cobalt doping.

8. The preparation method according to claim 1, characterized in that, The ruthenium doping method in step 4 is as follows: After cooling the cobalt-doped molybdenum disulfide / modified carbon cloth material rich in Mo vacancies to room temperature, it is immersed in a 0.01~0.05 M ruthenium salt solution for 8~12 h to fully adsorb the active metal ruthenium. After drying at 50~80 ℃ for 5~8 h, it is placed in a tube furnace and reduced at 180~220 ℃ for 0.5~1.5 h under a 5~15% H2 / 95~85% Ar2 atmosphere to obtain a ruthenium-cobalt bimetallic doped molybdenum disulfide / modified carbon cloth composite material.

9. The ruthenium-cobalt bimetallic doped molybdenum disulfide hydrogen evolution electrocatalyst material prepared by the preparation method according to any one of claims 1-8.

Images