CN113130216B - A kind of molybdenum disulfide@ZIF-67@CoO-NF composite material and its synthesis and application - Google Patents

Abstract

The invention relates to a molybdenum disulfide@ZIF‑67@CoO‑NF composite material and its synthesis and application. The method specifically includes the following steps: (a) mixing cobalt salt, urea and water to obtain a cobalt salt solution, and treating Soak the foamed nickel in the mixed solution, then carry out hydrothermal, drying and calcining to obtain the CoO-NF composite material in sequence; (b) get 2-methylimidazole and methanol solution and mix to obtain the imidazole solution, and then the step (a) The obtained CoO‑NF composite material is placed in an imidazole solution for self-loading to obtain a ZIF‑67@CoO‑NF composite material; (c) mixing molybdenum salt and sulfide to obtain a mixed solution, and then the obtained in step (b) The ZIF‑67@CoO‑NF composite was placed in a mixed solution for electrodeposition, and finally the molybdenum disulfide@ZIF‑67@CoO‑NF composite was obtained. Compared with the prior art, the Tafel slope and overpotential of the hydrogen evolution material of the present invention are lower, the energy barrier required to break through the hydrogen evolution is lower, the hydrogen conversion rate is higher, and the rate is faster.

Description

A kind of molybdenum disulfide@ZIF-67@CoO-NF composite material and its synthesis and application

technical field

The invention belongs to the technical field of hydrogen energy, and specifically relates to a MoS ₂ @ZIF-67@CoO-NF composite material and its synthesis and application.

Background technique

The global energy crisis and its related environmental problems have created an urgent need for clean, economical and sustainable energy. Hydrogen is known as a clean energy in the 21st century, and is regarded as an ideal energy alternative to fossil fuels due to its high energy density and environmental friendliness. Electrocatalytic water splitting for large-scale hydrogen production from abundant water sources is considered to be a facile route to this end. Currently, Pt group metals have been proven to be the most efficient electrocatalysts for the hydrogen evolution reaction (HER). However, low earth reserves and high cost greatly limit the widespread application of such metals. Therefore, it is highly desirable to develop alternative catalysts with low cost, similar catalytic efficiency, and good stability for the hydrogen evolution reaction.

In general, highly active HER electrocatalysts require the following features: (1) inherently high specific surface area; (2) high electrical conductivity and fast electron transfer pathways; (3) a large number of active sites and fast mass transport pathways ( including transport of reaction substrates and diffusion of gaseous products). Therefore, much research effort is devoted to developing alternatives with high efficiency and stability and abundant storage capacity. Nickel foam is a commercial metal functional material with three-dimensional openings, pores and metal skeleton interconnected. It is mostly used in nickel-hydrogen battery electrode materials, fuel cells and other fields. This kind of material has a large electrochemical reaction interface and has a great application prospect in electrochemical electrode materials.

和优异的热力学稳定性。然而，单个的MoS₂由于活性位点暴露较少、导电性较差，因此进一步显著提高这些基于TMDs的催化剂的催化性能以满足实际应用仍然存在巨大挑战。In order to solve the above problems and further enhance the electrochemical activity, several strategies targeting the above key issues have been proposed and some progress has been made so far. For example, transition metal dichalcogenides (TMDs) as promising materials for catalytic cathode HER, especially molybdenum disulfide (MoS ₂ ), have been the focus of extensive research due to its Pt-like catalytic properties with near-zero free capable of hydrogen adsorption

and excellent thermodynamic stability. However, due to the less exposed active sites and poor electrical conductivity of single MoS2, it still remains a great challenge to further significantly improve the catalytic performance of these TMDs _- based catalysts for practical applications.

Contents of the invention

The purpose of the present invention is to provide a method for in-situ synthesis of molybdenum disulfide@ZIF-67@CoO-NF composite material (molybdenum disulfide is represented by MoS ₂ in the following).

The second purpose of the present invention is to provide a MoS2@ZIF-67@CoO-NF composite material prepared by the above method.

The third object of the present invention is to provide an application of the above-mentioned MoS ₂ @ZIF-67@CoO-NF composite material.

The object of the present invention is achieved through the following technical solutions:

A method for in-situ synthesis of MoS ₂ @ZIF-67@CoO-NF composite material, the method specifically includes the following steps:

(a) Mix cobalt salt, urea and water to obtain a cobalt salt solution, soak the treated foamed nickel (referred to as NF) in the above cobalt salt solution, and then perform hydrothermal, drying and calcination in sequence to obtain a CoO-NF composite material ;

(b) Mix 2-methylimidazole and methanol to obtain an imidazole solution, and then place the CoO-NF composite material obtained in step (a) in the imidazole solution for self-loading to obtain a ZIF-67@CoO-NF composite material ;

(c) Mix molybdenum salt, sulfide and water to obtain a mixed solution, adjust the pH, then place the ZIF-67@CoO-NF composite material obtained in step (b) in the mixed solution for electrodeposition, and finally obtain MoS ₂ @ ZIF-67@CoO-NF composites.

In step (a), the molar ratio of cobalt salt and urea is 1:2.

In step (a), the cobalt salt is cobalt nitrate hexahydrate.

In step (a), the nickel foam treatment process is as follows: the nickel foam substrate is cut into a sample that meets the required size, ultrasonicated with acetone and absolute ethanol for 25-30 minutes in sequence, finally rinsed with deionized water, and then dried.

In step (a), ultrasonic dispersion is used during mixing, the ultrasonic power is 500-1000W, and the ultrasonic time is 1-5 minutes.

In step (a), the temperature of hydrothermal is 100-140°C. If the hydrothermal temperature is too high or too low (the same as the hydrothermal time), the sample structure will collapse or become unstable. Therefore, the preferred temperature is 120°C, and the hydrothermal time is 5-7h, preferably 6h.

In step (a), the drying is carried out in a vacuum drying oven at a drying temperature of 50-70° C., preferably 60° C., and dried overnight.

In step (a), the calcination is carried out in a resistance furnace without gas, the temperature of the calcination is 280-320°C, preferably 300°C, and the calcination time is 1.5-2.5h, preferably 2h.

In step (b), the molar volume ratio of 2-methylimidazole and methanol is 10mmol:20mL.

In step (b), the standing temperature is room temperature, and the standing time is 3 to 5 hours, preferably 4 hours. After the standing, it is washed for later use.

In step (c), the molar ratio of molybdenum salt and sulfide is 0.07:2.

In step (c), the molybdenum salt is molybdenum nitrate tetrahydrate, and the sulfide is sodium sulfide nonahydrate.

In step (c), add nitric acid to adjust pH, the volume addition of nitric acid is 0.1mL/0.07mmol molybdenum salt, the pH of mixture is about 12, is acidified to 7 with nitric acid, this operation pushes reaction equilibrium to product side, is conducive to Molybdenum disulfide formation.

In step (c), the electrodeposition adopts constant potential electrodeposition or CV electrodeposition;

The voltage of constant potential electrodeposition is -0.6～-1.0V, the temperature of constant potential electrodeposition is 20～25°C, and the time of constant potential electrodeposition is 2200～2600s, preferably 2400s;

The voltage of CV electrodeposition is 0.2～-1.2V, the temperature of CV electrodeposition is 20～25°C, and the boosting speed is 0.01 V/s.

A MoS ₂ @ZIF-67@CoO-NF composite material prepared by the method described above, in which the nickel foam has a porosity of about 95%, CoO-NF is the core, and ZIF-67 and MoS ₂ are wrapped in turn on the outer surface of CoO-NF.

An application of the above-mentioned MoS ₂ @ZIF-67@CoO-NF composite material in the electrocatalytic hydrogen evolution reaction, especially the application in the electrocatalytic hydrogen evolution in alkaline solution, in the application, the MoS ₂ @ZIF -67@CoO-NF composite as a working electrode in electrocatalytic hydrogen evolution reaction. Specifically:

(1) Prepare a 1.0M potassium hydroxide solution and feed nitrogen gas into the potassium hydroxide solution for 30 minutes to drive away the air in the solution, and use it as an electrolyte for later use.

(2) Wash the prepared MoS ₂ @ZIF-67@CoO-NF hydrogen evolution material with deionized water and isopropanol without drying, and directly use it as the working electrode in the electrocatalytic hydrogen evolution reaction.

(3) Connect MoS ₂ @ZIF-67@CoO-NF electrode, Ag/AgCl electrode, and platinum electrode to the working electrode, reference electrode, and counter electrode respectively, and clean MoS ₂ @ZIF with 1.0M potassium hydroxide solution The electrode surface of the -67@CoO-NF electrode was finally connected to an electrochemical workstation to measure the electrocatalytic hydrogen evolution performance of the hydrogen evolution material in a potassium hydroxide solution.

The present invention generates CoO through hydrothermal and calcination methods, then self-supports ZIF-67 on NF, and then generates MoS ₂ by using molybdenum salt and sulfide, which increases the specific surface area of the material and improves the contact area between the material and water. It makes hydrogen easier to produce, improves the nanostructure of the material, and improves the hydrogen evolution performance and stability of the material. In the composite material, the 3d orbital of metal molybdenum is in a half-filled state, which has a strong adsorption effect on hydrogen atoms. After being combined with foamed nickel, the hydrogen evolution performance of foamed nickel is greatly enhanced, and the composite effect of two transition metal elements further improves the Electrochemical performance, improved electrochemical performance and simple synthesis method; foamed nickel is a sound-absorbing "porous metal" with three-dimensional fully penetrated mesh structure performance, the porosity of foamed nickel is about 95%, water or gas can Unimpeded passage, the nickel skeleton is hollow and interconnected with each other in a metallurgical state, which has the advantages of good stability, high porosity, thermal shock resistance, small bulk density and large specific surface area.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The Tafel slope and overpotential of the hydrogen evolution material are low, the energy barrier required to break through the hydrogen evolution is low, and the hydrogen conversion rate is high and the rate is fast.

(2) MoS ₂ @ZIF-67@CoO-NF composite material is used as an alloy catalyst, which has a lower synthesis cost than most catalysts. The raw materials of the hydrogen evolution catalyst can be purchased, and the earth’s reserves are relatively sufficient, and there are no explosives or poisons drug.

Description of drawings

Figure 1 is a comparative diagram of the electrochemical performance of the MoS ₂ @ZIF-67@CoO-NF composite material obtained in Examples 1, 2, 3, and 4 and the ZIF-67@CoO-NF composite material obtained in Comparative Example 1;

Fig. 2 is the electrochemical performance comparison diagram of the MoS ₂ @ZIF-67@CoO-NF composite material obtained respectively in Examples 1, 2, 3, and 4 and the ZIF-67@CoO-NF composite material obtained in Comparative Example 1;

Fig. 3 is a material stability diagram of the MoS ₂ @ZIF-67@CoO-NF composite material obtained in Example 2.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

All raw materials used in the various embodiments of the present invention are commercially available unless otherwise specified.

Example 1

Raw materials: 1.0 mmol of cobalt nitrate hexahydrate

Urea 2.0mmol

2-Methylimidazole 10mmol

Methanol 20mL

Molybdenum nitrate tetrahydrate 0.07mmol

Sodium sulfide nonahydrate 2.0mmol

Nitric acid 0.1mL

A MoS ₂ @ZIF-67@CoO-NF composite material, prepared by the preparation method of the following steps:

(a) Mix 1.0mmol cobalt nitrate hexahydrate, 2.0mmol urea and deionized water to obtain a cobalt salt solution. When mixing, disperse ultrasonically for 2 minutes with a power of 1000W. 4cm of the sample, followed by ultrasonic 25min with acetone, absolute ethanol, finally rinsed with deionized water, and then dried, foamed nickel porosity is about 95%) soaked in the above-mentioned cobalt salt solution; then soaked with foamed nickel Move the cobalt salt solution to a hydrothermal autoclave for 6 hours at 120°C, and dry the foamed nickel in a vacuum oven at 60°C overnight to obtain a precursor; put the precursor into a resistance furnace under natural conditions Calcined at 300°C for 2h without gas in the resistance furnace, the CoO-NF composite material was obtained.

(b) Next, mix 10mmol 2-methylimidazole and 20mL methanol to obtain an imidazole solution, and place the CoO-NF composite material in the imidazole solution for self-loading. The standing temperature is room temperature and the standing time is 4h, and finally ZIF is obtained. -67@CoO-NF composites.

(c) ZIF-67@CoO-NF composite material was placed in a mixed aqueous solution containing 0.07mmol molybdenum nitrate tetrahydrate, 2.0mmol sodium sulfide nonahydrate, and 0.1mL nitric acid for constant potential electrodeposition, electrodeposition voltage: -0.6V ;Electrodeposition time: 2400s, electrodeposition temperature: 25°C, finally get MoS ₂ @ZIF-67@CoO-NF hydrogen evolution material, denoted as MoS ₂ @ZIF-67@CoO-NF-0.62400.

The MoS ₂ @ZIF-67@CoO-NF hydrogen evolution material in Example 1 is directly used as the working electrode in the electrocatalytic hydrogen evolution reaction without drying, specifically:

(1) The MoS ₂ @ZIF-67@CoO-NF hydrogen evolution material was washed twice with deionized water and isopropanol, respectively, and used as the working electrode in the electrocatalytic hydrogen evolution reaction without drying.

(2) Prepare 1.0M potassium hydroxide solution as the electrolyte for electrocatalysis, pass through nitrogen to drive away the air, then use MoS ₂ @ZIF-67@CoO-NF, Ag/AgCl electrode, platinum electrode as working electrode, The reference electrode and the counter electrode were connected to an electrochemical workstation, and the electrocatalytic hydrogen evolution performance of the electrode material was measured in the electrolyte, as shown in Figures 1 and 2 respectively (Figure 1 is a relationship diagram between current density and voltage, and Figure 2 is The relationship between overpotential and current density, the same below). It can be seen from Figure 1 that the overpotential is 205 mV at a current density of 10 mA cm ^-2 . It can be seen from Figure 2 that the Tafel slope of this material is 106.61mV dec ^-1 .

Example 2

Raw materials: 1.0 mmol of cobalt nitrate hexahydrate

Urea 2.0mmol

2-Methylimidazole 10mmol

Methanol 20mL

Molybdenum nitrate tetrahydrate 0.07mmol

Sodium sulfide nonahydrate 2.0mmol

Nitric acid 0.1mL

A MoS ₂ @ZIF-67@CoO-NF composite material, prepared by the preparation method of the following steps:

(a) 1.0mmol cobalt nitrate hexahydrate, 2.0mmol urea and deionized water were mixed to obtain a cobalt salt solution, which was ultrasonically dispersed for 5 minutes with a power of 1000W during mixing, and the treated foamed nickel was soaked in the above-mentioned cobalt salt solution; The cobalt salt solution soaked with foamed nickel was moved to a hydrothermal autoclave for 6 hours at 120°C, and the hydroheated nickel foam was dried overnight in a vacuum oven at 60°C to obtain a precursor; the precursor was placed in a resistor The furnace was calcined at 300°C for 2h under natural conditions, and no gas was introduced into the resistance furnace to obtain the CoO-NF composite material.

(b) Next, mix 10mmol 2-methylimidazole and 20mL methanol to obtain an imidazole solution, and place the CoO-NF composite material in the imidazole solution for self-loading. The standing temperature is room temperature and the standing time is 4h, and finally ZIF is obtained. -67@CoO-NF composites.

(c) ZIF-67@CoO-NF composite material was placed in a mixed aqueous solution containing 0.07mmol molybdenum nitrate tetrahydrate, 2.0mmol sodium sulfide nonahydrate, and 0.1mL nitric acid for constant potential electrodeposition, electrodeposition voltage: -0.8V ;Electrodeposition time: 2400s, electrodeposition temperature: 25°C, MoS ₂ @ZIF-67@CoO-NF hydrogen evolution material was finally obtained, denoted as MoS ₂ @ZIF-67@CoO-NF-0.82400.

The MoS ₂ @ZIF-67@CoO-NF hydrogen evolution material in Example 2 is directly used as the working electrode in the electrocatalytic hydrogen evolution reaction without drying, specifically:

(1) The MoS ₂ @ZIF-67@CoO-NF hydrogen evolution material was washed twice with deionized water and isopropanol, respectively, and used as the working electrode in the electrocatalytic hydrogen evolution reaction without drying.

(2) Prepare 1.0M potassium hydroxide solution as the electrolyte for electrocatalysis, pass through nitrogen to drive away the air, then use MoS ₂ @ZIF-67@CoO-NF, Ag/AgCl electrode, platinum electrode as working electrode, The reference electrode and the counter electrode were connected to an electrochemical workstation, and the electrocatalytic hydrogen evolution performance of the electrode material was measured in the electrolyte, as shown in Figures 1, 2, and 3, respectively. It can be seen from Figure 1 that the overpotential at a current density of 10mA cm ^-2 is 226mV. It can be seen from Figure 2 that the Tafel slope of the material is 64.85mV dec ^-1 . It can be seen from Figure 3 that The deviation between the LSV curve after 1000 cycles of CV test and the LSV curve before CV test is not large (1 represents before CV test, 2 represents after 1000 cycles of CV test), indicating that the material has good stability.

Example 3

Raw materials: 1.0 mmol of cobalt nitrate hexahydrate

Urea 2.0mmol

2-Methylimidazole 10mmol

Methanol 20mL

Molybdenum nitrate tetrahydrate 0.07mmol

Sodium sulfide nonahydrate 2.0mmol

Nitric acid 0.1mL

A MoS ₂ @ZIF-67@CoO-NF composite material, prepared by the preparation method of the following steps:

(a) 1.0mmol cobalt nitrate hexahydrate, 2.0mmol urea and deionized water were mixed to obtain a cobalt salt solution, which was ultrasonically dispersed for 5 minutes with a power of 1000W during mixing, and the treated foamed nickel was soaked in the above-mentioned cobalt salt solution; The cobalt salt solution soaked with foamed nickel was moved to a hydrothermal autoclave for 6 hours at 120°C, and the hydroheated nickel foam was dried overnight in a vacuum oven at 60°C to obtain a precursor; the precursor was placed in a resistor The furnace was calcined at 300°C for 2h under natural conditions, and no gas was introduced into the resistance furnace to obtain the CoO-NF composite material.

(b) Next, mix 10mmol 2-methylimidazole and 20mL methanol to obtain an imidazole solution, and place the CoO-NF composite material in the imidazole solution for self-loading. The standing temperature is room temperature and the standing time is 4h, and finally ZIF is obtained. -67@CoO-NF composites.

(c) ZIF-67@CoO-NF composite material was placed in a mixed aqueous solution containing 0.07mmol molybdenum nitrate tetrahydrate, 2.0mmol sodium sulfide nonahydrate, and 0.1mL nitric acid for constant potential electrodeposition, electrodeposition voltage: -1.0V ;Electrodeposition time: 2400s, electrodeposition temperature: 25°C, MoS ₂ @ZIF-67@CoO-NF hydrogen evolution material was finally obtained, denoted as MoS ₂ @ZIF-67@CoO-NF-1.02400.

The MoS ₂ @ZIF-67@CoO-NF hydrogen evolution material in Example 3 is directly used as the working electrode in the electrocatalytic hydrogen evolution reaction without drying, specifically:

(1) The MoS ₂ @ZIF-67@CoO-NF hydrogen evolution material was washed twice with deionized water and isopropanol, respectively, and used as the working electrode in the electrocatalytic hydrogen evolution reaction without drying.

(2) Prepare 1.0M potassium hydroxide solution as the electrolyte for electrocatalysis, pass through nitrogen to drive away the air, then use MoS ₂ @ZIF-67@CoO-NF, Ag/AgCl electrode, platinum electrode as working electrode, The reference electrode and the counter electrode were connected to an electrochemical workstation, and the electrocatalytic hydrogen evolution performance of the electrode material was measured in the electrolyte, as shown in Figures 1 and 2, respectively. It can be seen from Figure 1 that the overpotential at a current density of 10mA cm ^-2 is 234 mV, and it can be seen from Figure 2 that the Tafel slope of the material is 175.13mV dec ^-1 .

Example 4

Raw materials: 1.0 mmol of cobalt nitrate hexahydrate

Urea 2.0mmol

2-Methylimidazole 10mmol

Methanol 20mL

Molybdenum nitrate tetrahydrate 0.07mmol

Sodium sulfide nonahydrate 2.0mmol

Nitric acid 0.1mL

A MoS ₂ @ZIF-67@CoO-NF composite material, prepared by the preparation method of the following steps:

(a) 1.0mmol cobalt nitrate hexahydrate, 2.0mmol urea and deionized water were mixed to obtain a cobalt salt solution, which was ultrasonically dispersed for 5 minutes with a power of 1000W during mixing, and the treated foamed nickel was soaked in the above-mentioned cobalt salt solution; The cobalt salt solution soaked with foamed nickel was moved to a hydrothermal autoclave for 6 hours at 120°C, and the hydroheated nickel foam was dried overnight in a vacuum oven at 60°C to obtain a precursor; the precursor was placed in a resistor The furnace was calcined at 300°C for 2h under natural conditions, and no gas was introduced into the resistance furnace to obtain the CoO-NF composite material.

(b) Next, mix 10mmol 2-methylimidazole and 20mL methanol solution to obtain an imidazole solution, and place the CoO-NF composite material in the imidazole solution for self-loading. The standing temperature is room temperature and the standing time is 4h. Finally, ZIF-67@CoO-NF composites.

(c) The ZIF-67@CoO-NF composite material was placed in a mixed aqueous solution containing 0.07mmol molybdenum nitrate tetrahydrate, 2.0mmol sodium sulfide nonahydrate, and 0.1mL nitric acid for CV electrodeposition (0.2～-1.2V, 20～ 25°C, 0.01V/s), the MoS ₂ @ZIF-67@CoO-NF hydrogen evolution material was finally obtained, denoted as MoS ₂ @ZIF-67@CoO-NF CV.

The MoS ₂ @ZIF-67@CoO-NF hydrogen evolution material in Example 4 is directly used as the working electrode in the electrocatalytic hydrogen evolution reaction without drying, specifically:

(1) The MoS ₂ @ZIF-67@CoO-NF hydrogen evolution material was washed twice with deionized water and isopropanol, respectively, and used as the working electrode in the electrocatalytic hydrogen evolution reaction without drying.

(2) Prepare 1.0M potassium hydroxide solution as the electrolyte for electrocatalysis, pass through nitrogen to drive away the air, then use MoS ₂ @ZIF-67@CoO-NF, Ag/AgCl electrode, platinum electrode as working electrode, The reference electrode and the counter electrode were connected to an electrochemical workstation, and the electrocatalytic hydrogen evolution performance of the electrode material was measured in the electrolyte, as shown in Figures 1 and 2, respectively. It can be seen from Figure 1 that the overpotential at a current density of 10mA cm ^-2 is 285 mV, and it can be seen from Figure 2 that the Tafel slope of the material is 72.41mV dec ^-1 .

Comparative example 1

Raw materials: 1.0 mmol of cobalt nitrate hexahydrate

Urea 2.0mmol

2-Methylimidazole 10mmol

Methanol 20mL

A ZIF-67@CoO-NF composite material prepared by the preparation method of the following steps:

1.0mmol cobalt nitrate hexahydrate, 2.0mmol urea and deionized water to obtain a cobalt salt solution, ultrasonically disperse for 5 minutes with a power of 1000W when mixing, soak the treated foamed nickel in the above cobalt salt solution; then soak the foamed nickel The cobalt salt solution was moved to a hydrothermal autoclave at 120°C for 6 hours, and the hydrothermally heated nickel foam was dried overnight in a vacuum oven at 60°C to obtain a precursor; the precursor was placed in a resistance furnace under natural conditions Calcination at 300°C for 2h, without gas in the resistance furnace, to obtain CoO-NF composite material; then mix 10mmol 2-methylimidazole and 20mL methanol to obtain an imidazole solution, and put the CoO-NF composite material in the imidazole solution for self- load, the standing temperature is room temperature, and the standing time is 4h, and finally the ZIF-67@CoO-NF composite material is obtained.

The ZIF-67@CoO-NF hydrogen evolution material in Comparative Example 1 was dried as the working electrode in the electrocatalytic hydrogen evolution reaction, specifically:

(1) The ZIF-67@CoO-NF hydrogen evolution material was rinsed twice with deionized water and isopropanol and dried, and then directly used as the working electrode in the electrocatalytic hydrogen evolution reaction.

(2) Prepare 1.0M potassium hydroxide solution as the electrolyte for electrocatalysis, pass in nitrogen to drive away the air, then use ZIF-67@CoO-NF, Ag/AgCl electrode, and platinum electrode as working electrode and reference electrode respectively 1. Connect the counter electrode to an electrochemical workstation, and measure the electrocatalytic hydrogen evolution performance of the electrode material in the electrolyte, as shown in Figures 1 and 2 respectively. It can be seen from Figure 2 that the Tafel slope of the material is 94.76mV dec ^-1 , and it can be seen from Figure 1 that the overpotential at a current density of 10mA cm ^-2 is 402mV.

Comparing Examples 1, 2, 3, 4 and Comparative Example 1, it can be found that the MoS ₂ @ZIF-67@CoO-NF composite material of the present invention has low overpotential, which is beneficial to hydrogen evolution.

Example 5

In a preparation method of MoS ₂ @ZIF-67@CoO-NF composite material, in addition to step (a), when cobalt salt, urea and water are mixed, the power of 500W is used to disperse for 1min, and the nickel foam matrix is sequentially washed with acetone, anhydrous Ethanol ultrasonication for 30min, hydrothermal temperature is 140°C, hydrothermal time is 5h, drying temperature is 50°C, calcination temperature is 320°C, calcination time is 1.5h; in step (b), the standing time is 3h; step ( In c), the temperature of the constant potential electrodeposition is 25° C., and the time of the constant potential electrodeposition is 2600 s, and the rest are the same as in Example 1. The obtained MoS ₂ @ZIF-67@CoO-NF composite has good hydrogen evolution ability.

Example 6

In a preparation method of MoS ₂ @ZIF-67@CoO-NF composite material, in addition to step (a), when cobalt salt, urea and water are mixed, the power of 750W is used to disperse for 2min, and the nickel foam matrix is sequentially washed with acetone, anhydrous Ethanol ultrasonication for 27min, hydrothermal temperature is 100°C, hydrothermal time is 7h, drying temperature is 70°C, calcination temperature is 280°C, calcination time is 2.5h; in step (b), the standing time is 5h; step ( In c), the temperature of the constant potential electrodeposition is 20° C., and the time of the constant potential electrodeposition is 2200 s, and the rest are the same as in Example 1. The obtained MoS ₂ @ZIF-67@CoO-NF composite has good hydrogen evolution ability.

The above descriptions of the embodiments are for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative effort. Therefore, the present invention is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (8)

1. In-situ synthesis MoS ₂ Method for @ ZIF-67@ CoO-NF composite material, characterized in thatThe method specifically comprises the following steps:

(a) Mixing cobalt salt, urea and water to obtain a cobalt salt solution, soaking the processed foamed nickel in the cobalt salt solution, and sequentially carrying out hydrothermal treatment, drying and calcination to obtain a CoO-NF composite material;

(b) Mixing 2-methylimidazole and methanol to obtain an imidazole solution, standing the CoO-NF composite material obtained in the step (a) in the imidazole solution for self-loading to obtain a ZIF-67@ CoO-NF composite material;

(c) Mixing molybdenum salt, sulfide and water to obtain a mixed solution, adjusting the pH value, putting the ZIF-67@ CoO-NF composite material obtained in the step (b) into the mixed solution for electrodeposition, and finally obtaining MoS ₂ @ ZIF-67@ CoO-NF composite;

the MoS ₂ @ ZIF-67@ CoO-NF composite material takes CoO-NF as inner core, ZIF-67 and MoS ₂ The nickel foam is sequentially wrapped on the outer surface of CoO-NF, and the porosity of the nickel foam is 95%;

in the step (b), the molar volume ratio of the 2-methylimidazole to the methanol is 10mmol; and standing for 3 to 5 hours at room temperature, and washing for later use after standing is finished.

2. An in situ synthesized MoS according to claim 1 ₂ The method of @ ZIF-67@ CoO-NF composite material is characterized in that in the step (a), the molar ratio of cobalt salt to urea is 1;

in the step (a), the cobalt salt is cobalt nitrate hexahydrate;

in the step (a), the treatment process of the foamed nickel is specifically as follows: cutting the foam nickel substrate into samples with the required size, sequentially carrying out ultrasonic treatment for 25-30min by using acetone and absolute ethyl alcohol, finally washing by using deionized water, and then drying.

3. The in situ synthesized MoS of claim 1 ₂ The method of the @ ZIF-67@ CoO-NF composite material is characterized in that in the step (a), ultrasonic dispersion is adopted during mixing, the ultrasonic power is 500-1000W, and the ultrasonic time is 1-5min.

4. The in situ synthesized MoS of claim 1 ₂ A method of @ ZIF-67@ CoO-NF composite material, characterized in that in the step (a), the hydrothermal temperature is 100 to 140 ℃ and the hydrothermal time is 5 to 7h;

in the step (a), drying is carried out in a vacuum drying oven at the drying temperature of 50-70 ℃ overnight;

in the step (a), the calcination is carried out in a resistance furnace, no gas is introduced into the resistance furnace, the calcination temperature is 280-320 ℃, and the calcination time is 1.5-2.5 h.

5. An in situ synthesized MoS according to claim 1 ₂ A process of @ ZIF-67@ coo-NF composite, characterized in that in step (c) the molar ratio of molybdenum salt to sulfide is 0.07;

in the step (c), nitric acid is added to adjust the pH, and the volume addition amount of the nitric acid is 0.1mL/0.07mmol of molybdenum salt;

in the step (c), the molybdenum salt is molybdenum nitrate tetrahydrate, and the sulfide is sodium sulfide nonahydrate.

6. The in situ synthesized MoS of claim 1 ₂ The method of @ ZIF-67@ CoO-NF composite material is characterized in that in the step (c), the electrodeposition adopts constant potential electrodeposition or CV electrodeposition;

the voltage of the constant potential electrodeposition is-0.6 to-1.0V, the temperature of the constant potential electrodeposition is 20 to 25 ℃, and the time of the constant potential electrodeposition is 2200 to 2600s;

the voltage of CV electrodeposition is 0.2 to-1.2V, the temperature of CV electrodeposition is 20 to 25 ℃, and the boosting speed is 0.01V/s.

7. MoS produced by the method of any one of claims 1 to 6 ₂ @ ZIF-67@ CoO-NF composite material.

8. MoS according to claim 7 ₂ The application of the @ ZIF-67@ CoO-NF composite material in the electrocatalytic hydrogen evolution reaction is characterized in that MoS ₂ The @ ZIF-67@ CoO-NF composite material is used as a working electrode in the electrocatalytic hydrogen evolution reaction.

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