阅读说明：本技术 共生孪晶Ni2Mo6S6O2/MoS2二维纳米片的合成方法 (Intergrown twin crystal Ni2Mo6S6O2/MoS2Synthesis method of two-dimensional nanosheet ) 是由 汪福宪 成晖 卫莉玲 刘琼 于 2021-01-08 设计创作，主要内容包括：本发明公开了一种暴露(00L)晶面的共生孪晶Ni-2Mo-6S-6O-2/MoS-2二维纳米片的合成方法,采用离子插入法限制Ni离子位于Mo基化合物的晶格矩阵中,形成Ni-Mo键合的前驱体,通过精确调控硫气氛浓度,利用Ni元素在Mo基化合物晶格矩阵中的重构作用,形成双核金属硫化物Ni-2Mo-6S-6O-2,同时利用限域生长单晶方法精确调控Ni-2Mo-6S-6O-2的生长方向,以单晶MoS-2为生长模板,沿单晶MoS-2的(110)晶面与单晶MoS-2交替生长,形成Ni-2Mo-6S-6O-2与MoS-2双晶共生的孪晶Ni-2Mo-6S-6O-2/MoS-2二维纳米片,可以作为高效催化剂直接应用于电催化水分解析氢反应。(The invention discloses a symbiotic twin crystal Ni exposing a (00L) crystal face 2 Mo 6 S 6 O 2 /MoS 2 The synthesis method of the two-dimensional nanosheet adopts an ion insertion method to limit Ni ions to be positioned in a lattice matrix of a Mo-based compound to form a Ni-Mo bonded precursor, and forms binuclear gold by accurately regulating and controlling the concentration of sulfur atmosphere and utilizing the reconstruction effect of Ni elements in the lattice matrix of the Mo-based compoundBelongs to sulfide Ni 2 Mo 6 S 6 O 2 And simultaneously accurately regulating and controlling Ni by utilizing a limited-area single crystal growth method 2 Mo 6 S 6 O 2 In the direction of growth of single crystal MoS 2 For growing templates, MoS along single crystal 2 Crystal face of (110) and single crystal MoS 2 Alternatively grow to form Ni 2 Mo 6 S 6 O 2 And MoS 2 Twin crystal Ni of twinning 2 Mo 6 S 6 O 2 /MoS 2 The two-dimensional nanosheet can be used as an efficient catalyst to be directly applied to the electrocatalytic hydrogen decomposition reaction.)

1. Symbiotic twin crystal Ni with (00L) crystal face exposed₂Mo₆S₆O₂/MoS₂The synthesis method of the two-dimensional nanosheet is characterized in that an ion insertion method is adopted to limit Ni ions to be located in a lattice matrix of a Mo-based compound to form a Ni-Mo bonded precursor, and the concentration of a sulfur atmosphere is accurately regulated to form a binuclear metal sulfide Ni₂Mo₆S₆O₂And simultaneously accurately regulating and controlling Ni by utilizing a limited-area single crystal growth method₂Mo₆S₆O₂In the growth direction of Ni₂Mo₆S₆O₂With single crystals MoS₂For growing templates, MoS along single crystal₂Crystal face of (110) and single crystal MoS₂Alternatively grow to form Ni₂Mo₆S₆O₂And MoS₂Twin crystal Ni of twinning₂Mo₆S₆O₂/MoS₂Two-dimensional nanosheets.

2. Intergrown twin Ni as defined in claim 1₂Mo₆S₆O₂/MoS₂The synthesis method of the two-dimensional nanosheet is characterized by comprising the following steps:

1) dissolving a molybdenum source and a nickel source in H₂O₂Heating the solution at constant temperature until the molybdenum source and the nickel source are completely dissolved in the aqueous solution to obtain a solution A; mo of the molybdenum source and the nickel source: the molar ratio of Ni is 1: 1-1: 2, H₂O₂The mass percent of the aqueous solution is 1-10 wt.%, and the heating temperature is 60-90 ℃;

2) placing soluble salt in pure water, heating and stirring, stopping heating and stirring after crystallization occurs above the solution, and cooling in ice water to obtain a saturated solution B containing a large amount of undissolved soluble salt solids; the soluble salt comprises sodium chloride, potassium chloride, sodium sulfate and potassium sulfate;

3) mixing and stirring the solution A, the solution B and all undissolved soluble salt solids in the step 2) to obtain a mixture C;

4) placing the mixture C in liquid nitrogen for freezing, then placing the mixture C in a vacuum freeze dryer for vacuum freeze drying for 12-48 hours to obtain a dry solid, placing the obtained dry solid in a porcelain boat A, placing the porcelain boat A in the center of a tube furnace, placing another porcelain boat B containing a sulfur source at the upper air inlet of the porcelain boat, and accurately adjusting the distance between the porcelain boat A and the porcelain boat B to be 3-4 cm;

5) introducing inert gas into the tubular furnace, regulating the flow rate of the inert gas to be 10-25 mL/min, and carrying out constant-temperature calcination by programming to the target temperature; the temperature rising speed is 1-10 ℃/min, the target temperature is 300-500 ℃, and the constant-temperature calcination time is 1-10 hours;

6) taking out the porcelain boat A after the vulcanization is finished, cleaning the sample in the porcelain boat A by using pure water and ethanol, and then putting the cleaned sample in the porcelain boat ADrying at room temperature to obtain the product of symbiotic twin crystal Ni₂Mo₆S₆O₂/MoS₂Two-dimensional nanosheets.

3. Intergrown twin Ni as defined in claim 2₂Mo₆S₆O₂/MoS₂The method for synthesizing the two-dimensional nanosheets is characterized in that the molybdenum source comprises molybdenum powder, molybdenum trioxide, molybdenum dioxide, ammonium molybdate and molybdenum acetylacetonate; the nickel source comprises nickel nitrate, nickel acetylacetonate and nickel chloride.

4. Intergrown twin Ni as defined in claim 2₂Mo₆S₆O₂/MoS₂The synthesis method of the two-dimensional nanosheet is characterized in that the mass of the soluble salt in the step 2) is 10-50 g, the volume of pure water is 5-30 mL, and the heating temperature is 50-100 ℃.

5. Intergrown twin Ni as defined in claim 2₂Mo₆S₆O₂/MoS₂The synthesis method of the two-dimensional nanosheet is characterized in that the volume of the transfer solution A in the step 3) is 0.05-0.2 mL, and the volume of the transfer solution B is 0.5-2 mL.

6. Intergrown twin Ni as defined in claim 2₂Mo₆S₆O₂/MoS₂The synthesis method of the two-dimensional nanosheet is characterized in that the sulfur source in the step 4) comprises thiourea and elemental sulfur, and the mass of the sulfur source is 10-40 g.

7. Intergrown twin Ni as defined in claim 2₂Mo₆S₆O₂/MoS₂The synthesis method of the two-dimensional nanosheet is characterized in that the inert gas in the step 5) comprises nitrogen and argon.

8. Intergrown twin crystal Ni with exposed (00L) crystal face obtained by the synthesis method of any one of claims 1 to 7₂Mo₆S₆O₂/MoS₂The application of the two-dimensional nano-sheet in electrocatalysis water decomposition hydrogen analysis reaction.

The technical field is as follows:

the invention relates to the field of catalysis, in particular to symbiotic twin crystal Ni exposing (00L) crystal face₂Mo₆S₆O₂/MoS₂A method for synthesizing two-dimensional nano-sheets.

Background art:

the demand for hydrogen energy and high hydrogen quality (i.e., hydrogen purity) is increasingly multiplied against the background of the era of the new generation of energy, particularly the gradual replacement of gasoline vehicles by hydrogen vehicles. Therefore, the hydrogen production technology of the hydrogen production industry as the upstream industry plays a crucial role in the development of the hydrogen energy industry. The water electrolysis hydrogen production technology as a novel hydrogen production technology is found to have unique advantages in the new hydrogen generation industry. Nevertheless, the traditional commercial Pt/C catalyst has greatly hindered the popularization and industrial application of the electrolytic water process due to its expensive cost. Therefore, the key to further improve the efficiency and reduce the cost of water electrolysis is to find a cheap and efficient cathode water electrolysis catalyst. Among the many alternative inexpensive catalysts, molybdenum sulfide is of great interest due to its outstanding hydrogen evolution from water electrolysis (HER). However, the HER performance of molybdenum sulfide, particularly in the high current regime, is still less than desirable. Specifically, this is because molybdenum sulfide in the mononuclear active site mode (i.e., Mo active site) cannot simultaneously satisfy the effective adsorption of two intermediate products, H and OH, which ultimately results in a reaction process that requires overcoming a large energy barrier, resulting in H₂The O decomposition rate is slower. Thus, in the catalysis ofThe introduction of a second active site with optimal adsorption capacity of OH into the material can well reduce H₂An energy barrier in the O decomposition process, thereby promoting the catalytic reaction of the electrolyzed water.

The invention content is as follows:

the invention aims to provide intergrown twin Ni with an exposed (00L) crystal face₂Mo₆S₆O₂/MoS₂A synthesis method of a two-dimensional nanosheet comprises the steps of limiting Ni ions to be located in a lattice matrix of a Mo-based compound by adopting an ion insertion method to form a Ni-Mo bonded precursor, and forming a binuclear metal sulfide Ni by accurately regulating and controlling the concentration of sulfur atmosphere₂Mo₆S₆O₂And simultaneously accurately regulating and controlling Ni by utilizing a limited-area single crystal growth method₂Mo₆S₆O₂In the growth direction of Ni₂Mo₆S₆O₂In the form of single crystal MoS₂For growing templates, MoS along single crystal₂Crystal face of (110) and single crystal MoS₂Alternatively grow to form Ni₂Mo₆S₆O₂And MoS₂Twin crystal Ni of twinning₂Mo₆S₆O₂/MoS₂Two-dimensional nanosheets.

The invention is realized by the following technical scheme:

symbiotic twin crystal Ni with (00L) crystal face exposed₂Mo₆S₆O₂/MoS₂A synthesis method of a two-dimensional nanosheet comprises the steps of limiting Ni ions to be located in a lattice matrix of a Mo-based compound by adopting an ion insertion method to form a Ni-Mo bonded precursor, and forming a binuclear metal sulfide Ni by accurately regulating and controlling the concentration of sulfur atmosphere₂Mo₆S₆O₂And simultaneously accurately regulating and controlling Ni by utilizing a limited-area single crystal growth method₂Mo₆S₆O₂In the growth direction of Ni₂Mo₆S₆O₂In the form of single crystal MoS₂For growing templates, MoS along single crystal₂Crystal face of (110) and single crystal MoS₂Alternatively grow to form Ni₂Mo₆S₆O₂And MoS₂Twin crystal Ni of twinning₂Mo₆S₆O₂/MoS₂Two-dimensional nanosheets.

The method specifically comprises the following steps:

1) dissolving a molybdenum source and a nickel source in H₂O₂Heating the solution at constant temperature until the molybdenum source and the nickel source are completely dissolved in the aqueous solution to obtain a solution A; mo of the molybdenum source and the nickel source: the molar ratio of Ni is 1: 1-1: 2, H₂O₂The mass percent of the aqueous solution is 1-10 wt.%, and the heating temperature is 60-90 ℃;

2) placing soluble salt in pure water, heating and stirring, stopping heating and stirring after crystallization occurs above the solution, and cooling in ice water to obtain a saturated solution B containing a large amount of undissolved soluble salt solids; the soluble salt comprises sodium chloride, potassium chloride, sodium sulfate and potassium sulfate;

3) mixing and stirring the solution A, the solution B and all undissolved soluble salt solids in the step 2) to obtain a mixture C, wherein the undissolved soluble salt solids can greatly enhance the confinement effect, and greatly limit the product to grow along a single direction, so that the product finally grows into a single-crystal two-dimensional nanosheet;

4) placing the mixture C in liquid nitrogen for freezing, then placing the mixture C in a vacuum freeze dryer for vacuum freeze drying for 12-48 hours to obtain a dry solid, placing the obtained dry solid in a porcelain boat A, placing the porcelain boat A in the center of a tube furnace, placing another porcelain boat B containing a sulfur source at the upper air inlet of the porcelain boat, and precisely adjusting the distance between the porcelain boat A and the porcelain boat B to 3-4cm to obtain a target product, so that the sulfur source concentration above the porcelain boat A is moderate, and the phenomenon that the sulfur source concentration is too high to damage the Ni-Mo structure to form an independent NiS₂And MoS₂；

5) Introducing inert gas into the tubular furnace, regulating the flow rate of the inert gas to be 10-25 mL/min, and carrying out constant-temperature calcination by programming to the target temperature; the temperature rising speed is 1-10 ℃/min, the target temperature is 300-500 ℃, and the constant-temperature calcination time is 1-10 hours;

6) taking out the porcelain boat A after the vulcanization is finished, cleaning a sample in the porcelain boat A by using pure water and ethanol, and drying at room temperature to obtain a product which is symbiotic twin crystal Ni₂Mo₆S₆O₂/MoS₂Two-dimensional nanosheets.

The molybdenum source comprises molybdenum powder, molybdenum trioxide, molybdenum dioxide, ammonium molybdate and molybdenum acetylacetonate, and the nickel source comprises nickel nitrate, nickel acetylacetonate and nickel chloride.

The mass of the soluble salt in the step 2) is 10-50 g, the volume of the pure water is 5-30 mL, and the heating temperature is 50-100 ℃.

And 3) the volume of the transfer solution A is 0.05-0.2 mL, and the volume of the transfer solution B is 0.5-2 mL.

And 4) the sulfur source comprises thiourea and elemental sulfur, and the mass of the sulfur source is 10-40 g.

And 5) the inert gas comprises nitrogen and argon.

The invention also protects the application of the symbiotic twin crystal two-dimensional nanosheet with the exposed (00L) crystal face obtained by the synthesis method in the electrocatalytic water-splitting hydrogen-analyzing reaction.

The invention has the following beneficial effects:

1) the method creatively adopts the confinement effect to accurately limit the Ni ions to be positioned in the lattice matrix of the Mo-based ions to form a Ni-Mo bonded precursor, and accurately regulates and controls the concentration of the sulfur atmosphere, so that the reconstruction effect of Ni elements in the lattice matrix of the Mo-based compound is utilized to form the binuclear metal sulfide Ni₂Mo₆S₆O₂. In addition, Ni is precisely regulated and controlled by using a limited-area single crystal growth method₂Mo₆S₆O₂In the growth direction of MoS₂Making Ni for growth of template₂Mo₆S₆O₂Along MoS₂(110) crystal face and MoS₂Alternatively grow to form Ni₂Mo₆S₆O₂And MoS₂Intergrown twin Ni exposing (00L) crystal face₂Mo₆S₆O₂/MoS₂Two-dimensional nanosheets.

2) The intergrowth twin crystal Ni of the (00L) crystal face is exposed by the invention₂Mo₆S₆O₂/MoS₂The two-dimensional nanosheet can be used as an efficient catalyst to be directly applied to the electrocatalytic hydrogen decomposition reaction.

Description of the drawings:

FIG. 1 is Ni₂Mo₆S₆O₂/MoS₂The topography of the scanning electron microscope.

FIG. 2 is Ni₂Mo₆S₆O₂/MoS₂The atomic force microscope topography of (1).

FIG. 3 is Ni₂Mo₆S₆O₂/MoS₂The fast-scan (scan speed 10 deg./min) spectrum of the X-ray diffraction test.

FIG. 4 is Ni₂Mo₆S₆O₂/MoS₂The fast-scan (scan speed 0.1 deg/min) spectrum of the X-ray diffraction test.

FIG. 5 is Ni₂Mo₆S₆O₂/MoS₂The selected area electron diffraction spectrum of (1).

FIG. 6 is Ni₂Mo₆S₆O₂/MoS₂、NiS₂And MoS₂Linear scan graph of (a).

FIG. 7 is Ni₂Mo₆S₆O₂/MoS₂Linear scan plot with Pt/C (20%).

FIG. 8 is Ni₂Mo₆S₆O₂/MoS₂Multi-step galvanostatic plot against Pt/C (20%).

The specific implementation mode is as follows:

the following is a further description of the invention and is not intended to be limiting.

Example 1: symbiotic twin crystal Ni with (00L) crystal face exposed₂Mo₆S₆O₂/MoS₂Synthesis method of two-dimensional nanosheet

The method comprises the following steps:

1) mixing a molybdenum source and a nickel source in a Mo: the molar ratio of Ni is 1: 1.5 dissolved in 5% by weight of H₂O₂Heating the solution at a constant temperature of 60 ℃ in the aqueous solution until the molybdenum source and the nickel source are completely dissolved to obtain a solution A;

2) placing 20g of soluble salt in 15mL of pure water, heating to 60 ℃, continuously stirring, stopping heating and stirring after crystallization occurs above the solution, and cooling in ice water to obtain a saturated solution B containing a large amount of undissolved soluble salt solids;

3) mixing and stirring 0.1mL of solution A, 1mL of solution B and all undissolved soluble salt solids in the step 2) to obtain a mixture C;

4) and placing the mixture C in liquid nitrogen for freezing, and then placing the mixture C in a vacuum freeze dryer for vacuum freeze drying for 24 hours. Placing the obtained dry solid in a porcelain boat A, placing the porcelain boat A in the center of a tube furnace, placing another porcelain boat B containing 20g of sulfur source at the upper air inlet of the porcelain boat, and accurately adjusting the distance between the porcelain boat A and the porcelain boat B to be 3.5cm, so that the concentration of the sulfur source above the porcelain boat A is moderate, and the phenomenon that the concentration of the sulfur source is too high to damage a Ni-Mo structure to form independent NiS (nickel-molybdenum sulfide) is prevented₂And MoS₂；

5) Introducing inert gas into the tubular furnace, wherein the flow rate of the inert gas is 15mL/min, heating to 400 ℃ at the speed of 5 ℃/min, and heating at constant temperature for 5 hours;

6) taking out the porcelain boat A after the vulcanization is finished, cleaning a sample in the porcelain boat A by using pure water and ethanol, and drying at room temperature to obtain a product which is symbiotic twin crystal Ni₂Mo₆S₆O₂/MoS₂Two-dimensional nanosheet, Ni produced₂Mo₆S₆O₂/MoS₂The morphology of the nano-sheet is two-dimensional nano-sheet (shown in figure 1), the average thickness of the nano-sheet is about 4.3nm (shown in figure 2), and the structure of the nano-sheet is Ni exposing (00L) crystal face₂Mo₆S₆O₂And MoS₂Intergrown twin phase structure (as shown in fig. 3, 4 and 5).

Example 2:

reference example 1, except that: the mass ratio of the molybdenum source to the nickel source is 1: 1.5-1: 2, H₂O₂The mass percentage of the aqueous solution is 5-10%, and the heating temperature is 60-90 ℃.

Example 3:

reference example 1, except that: the mass of the soluble salt is 20-50 g, the volume of the pure water is 15-30 mL, and the heating temperature is 60-100 ℃.

Example 4:

reference example 1, except that: the volume of the transferred solution A is 0.1-0.2 mL, and the volume of the transferred solution B is 1-2 mL.

Example 5:

reference example 1, except that: the time of vacuum freeze drying is 24-48 hours, the mass of the sulfur source is 20-40 g, and the distance between the porcelain boat A and the porcelain boat B is accurately adjusted to be 3.5-4 cm.

Example 6:

reference example 1, except that: the flow rate of the inert gas is 15-25 mL/min, the heating rate is 5-10 ℃/min, the target temperature is 400-500 ℃, and the constant temperature time is 5-10 hours.

Application example 1:

ni obtained in example 1₂Mo₆S₆O₂/MoS₂And the two-dimensional nanosheets are loaded on the carbon cloth to serve as catalytic electrodes. Mixing Ni₂Mo₆S₆O₂/MoS₂Two-dimensional nanosheet catalytic electrode and NiS synthesized using the same₂And MoS₂Respectively carrying out linear scanning on the catalytic materials, and specifically comprising the following steps:

using a three-electrode configuration, catalytic electrode (Ni)₂Mo₆S₆O₂/MoS₂、NiS₂、MoS₂) As a working electrode, Ag/AgCl was used as a reference electrode and platinum was used as a counter electrode. The electrolyte is a sodium hydroxide aqueous solution containing 1 mol/L. Linear scanning was tested at 10mV/s and the results of linear scanning curve (LSV) comparison showed (FIG. 6) Ni₂Mo₆S₆O₂/MoS₂Has a HER performance stronger than that of NiS₂And MoS₂Illustrating Ni₂Mo₆S₆O₂/MoS₂Has the difference from NiS₂And MoS₂Active site of (MoS)₂The active site of (A) is Mo-S, NiS₂Active site of (2) is Ni-S), also indicating Ni₂Mo₆S₆O₂/MoS₂The main active site in (1) is Ni₂Mo₆S₆O₂Rather than MoS₂。Ni₂Mo₆S₆O₂/MoS₂Is superior to MoS₂HER performance at MoS is demonstrated₂The introduction of Ni can effectively improve MoS₂The performance of (c).

Application example 2:

ni obtained in example 1₂Mo₆S₆O₂/MoS₂And the two-dimensional nanosheets are loaded on the carbon cloth to serve as catalytic electrodes. Mixing Ni₂Mo₆S₆O₂/MoS₂The two-dimensional nanosheet catalytic electrode and a commercial platinum-carbon (20%) electrode are subjected to linear scanning test, and the method comprises the following specific steps:

using a three-electrode configuration, adding Ni₂Mo₆S₆O₂/MoS₂Two-dimensional nanosheet catalytic electrode and commercial platinum carbon (20%) catalyst as working electrodes, Ag/AgCl as reference electrode, platinum as counter electrode. The electrolyte is a sodium hydroxide aqueous solution containing 1 mol/L. Linear scanning was tested at 10mV/s and the results of linear scanning curve (LSV) comparison showed (FIG. 7) Ni₂Mo₆S₆O₂/MoS₂Has an initial potential close to that of Pt/C (20%), and Ni increases with the increase of overpotential₂Mo₆S₆O₂/MoS₂The reaction current is increased by far more than Pt/C (20%), and finally Ni is added under larger over-potential₂Mo₆S₆O₂/MoS₂Exhibits HER activity superior to Pt/C (20%).

Application example 3:

ni obtained in example 1₂Mo₆S₆O₂/MoS₂And the two-dimensional nanosheets are loaded on the carbon cloth to serve as catalytic electrodes. Mixing Ni₂Mo₆S₆O₂/MoS₂Step constant current test is carried out on a two-dimensional nanosheet catalytic electrode and a commercial platinum-carbon (20%) electrode, and the steps are as follows:

using a three-electrode configuration, adding Ni₂Mo₆S₆O₂/MoS₂Two-dimensional nanosheet catalytic electrode and commercial platinum carbon (20%) catalyst as working electrodes, Ag/AgCl as reference electrode, platinum as counter electrode. The electrolyte contains 1mol/LAqueous sodium hydroxide solution. The step constant current test is respectively 10mA/cm²、20mA/cm²、50mA/cm²、100mA/cm²And 200mA/cm²The test was carried out under conditions of 60 seconds per test period. The stepped constant current curve (FIG. 8) shows Ni₂Mo₆S₆O₂/MoS₂Superior HER activity: at a current density of 250mAcm^-2Lower, Ni₂Mo₆S₆O₂/MoS₂The overpotential of (a) is 0.09V, close to Pt/C (20%), and the overpotential of Pt/C (20%) is-0.01V; with increasing current density, Ni₂Mo₆S₆O₂/MoS₂The overpotential with Pt/C (20%) is gradually reduced, and finally the current density is more than 50mAcm^-2Then show Ni₂Mo₆S₆O₂/MoS₂Has less over-potential advantage than Pt/C (20%). Thus, the current hydrogen production industry in electrolysis requires that the HER activity of the catalyst be judged at current densities greater than 100mAcm^-2In the case of (2), Ni₂Mo₆S₆O₂/MoS₂The activity is remarkably superior to Pt/C (20%) and the cheapness is also improved.

While the preferred embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.