CN115261885A - Preparation of RuSe2/Co-N-C nanocomposite and its application in hydrogen evolution under alkaline conditions - Google Patents

Abstract

RuSe₂Preparation of/Co-N-C nano composite material and hydrogen evolution application thereof under alkaline condition. The invention belongs to the field of electrocatalytic preparation and application, and particularly relates to RuSe₂Preparation of/Co-N-C nano composite material and application thereof in electrocatalytic hydrogen evolution. The preparation method comprises the steps of firstly preparing a white crystalline Co and N doped carbon nanosheet precursor through a solid pyrolysis method, then synthesizing the Co-N-C nanosheet through high-temperature annealing in a tube furnace, and then carrying out a hydrothermal method on RuSe₂Uniformly growing on Co-N-C nano-sheets, and finally annealing in a tube furnace to obtain RuSe₂a/Co-N-C nanocomposite. Benefit from Co functionalization and unique heterogeneitySynergistic effect of interface initiation, ruSe₂the/Co-N-C heterostructure electrocatalyst has good Hydrogen Evolution (HER) performance in alkalinity. Synthetic RuSe₂the/Co-N-C heterostructure electrocatalyst has the advantages of simple synthesis operation, environmental friendliness, no pollution and the like, and has excellent HER activity and stability.

Description

Preparation of RuSe2/Co-N-C Nanocomposite and Its Hydrogen Evolution under Alkaline Conditions application

technical field

The invention belongs to the field of electrocatalyst preparation and application, and in particular relates to the preparation and application of a RuSe ₂ /Co-NC nanocomposite material.

Background technique

The energy crisis is hindering the social and economic development of the world, and there is an urgent need to develop clean energy. Hydrogen (H ₂ ) has been considered as a potential clean energy because of its high energy density and low environmental pollution. Electrocatalytic hydrogen evolution is an efficient and green technology for _H2 production. Although noble metal Pt-based electrocatalysts can achieve stable, efficient, and continuous H _evolution , they are not suitable for widespread applications due to their high cost and scarce supply. Therefore, it is imminent to develop a new non-noble metal electrocatalyst that can replace Pt with high efficiency and low cost.

Although Ru is also a rare transition metal element, its price is less than a quarter of that of Pt, and metal Ru itself has good catalytic activity and catalytic stability. Numerous studies have shown that Ru can be combined with group VA or VIA nonmetallic elements to become effective electrocatalysts, which can have a hydrogen-binding strength similar to that of Pt, and exhibit good HER activity and corrosion resistance. It has been confirmed that RuS ₂ , RuSe ₂ and RuTe ₂ as TMDCs are a class of excellent electrocatalysts for HER.

Meanwhile, the too slow water molecule adsorption and dissociation step (Volmer step) is the main reason for the poor alkaline HER kinetics. After the Volmer step, the adsorbed hydrogen atoms ( _Had ) recombine into _H2 and then desorb from the electrocatalyst. _H2O , OH _ad , and _Had are independent intermediates in these basic reactions, basically, an ideal catalyst should have a balanced adsorption capacity for each reaction intermediate to achieve fast HER kinetics in alkaline media . It is a rational design strategy to construct heterostructured electrocatalysts to trigger a synergistic effect at the heterointerface to enhance the basic HER kinetics. Specifically, one component in the heterostructure acts as a water dissociation promoter, while the other part is responsible for the subsequent HER process. Carbon-based materials have the remarkable advantage of high electrical conductivity and have been widely used as electrocatalyst supports. However, they hardly have the function of decomposing _H2O by themselves, so they cannot be used as catalyst promoters for basic HER. Therefore, it will be of great significance to endow carbonaceous materials with good electrical conductivity to accelerate the Volmer step to develop efficient heterostructured electrocatalysts for alkaline HER.

In the present invention, we propose a transition metal functionalization strategy and the synthesis of multifunctional carbon nanosheets as electrocatalyst supports for alkaline HER. Specifically, atomically dispersed Co species are confined in N-doped carbon nanosheets (Co-NCs) to endow the carbon nanosheets with additional water adsorption and dissociation functions. The doping of N destroys the electronic neutrality of carbon and induces the polarization of adjacent carbon atoms to facilitate the activation of _H2 molecules. The obtained RuSe ₂ /Co-NC composite has excellent HER performance and stability under alkaline conditions.

Contents of the invention

The object of the present invention is to provide a RuSe ₂ /Co-NC composite material and a preparation method thereof, and apply it to electrolyze water under alkaline conditions to prepare hydrogen, which has excellent HER performance and stability.

Technical solution of the present invention: the present invention provides a RuSe ₂ /Co-NC composite material, the preparation method of the catalyst is, through multi-step synthesis of RuSe ₂ /Co-NC nanocomposite material, first prepare a The white crystalline Co and N-doped carbon nanosheet precursors were synthesized by high-temperature annealing in a tube furnace to synthesize Co-NC nanosheets, and then RuSe ₂ was uniformly grown on Co-NC nanosheets by a hydrothermal method, and finally RuSe ₂ /Co-NC nanocomposites were obtained by annealing in a tube furnace.

The specific process is:

(1) Synthesis of Co and N-doped carbon nanosheets by solid-state pyrolysis. Specifically, take a certain amount of cobalt(II) acetylacetonate as a cobalt source, dissolve it together with urea and glucose into a beaker filled with deionized water, and ultrasonically stir at room temperature for 120min, and then a pink Transparent homogeneous solution. Among them, the mass ratio of cobalt (II) acetylacetonate and urea is 1:150-200, and the mass ratio of cobalt (II) acetylacetonate and glucose is 1:10-15.

The present invention selects glucose as the carbon source, cobalt acetylacetonate as the cobalt source, and urea as the nitrogen source to obtain better cobalt-nitrogen-doped carbon nanosheets. If the carbon source, cobalt source, and nitrogen source are replaced by other components, the morphology of the cobalt-nitrogen-doped carbon nanosheets will be affected, thereby affecting the electrocatalytic performance. At the same time, carbon nanosheets prepared from different raw materials will have different thicknesses in the nanosheets, as well as the ratio and distribution of cobalt and nitrogen elements, which are all important factors affecting the activity of the catalyst.

Preferably, the mass ratio of cobalt (II) acetylacetonate to urea is 1:160, and the mass ratio of cobalt (II) acetylacetonate to glucose is 1:10.

( ₂ ) The above-mentioned beaker is placed in a blast drying oven, and the pink solution is completely evaporated to dryness to obtain a white crystalline precursor, which is filled in a crucible and transferred to a tube furnace, and N is introduced as a protective gas. ℃． The temperature was raised to 900 °C at a min ^-1 heating rate and then kept at the temperature for calcination for 5 h. After the calcination was completed, N ₂ was continued to pass through and naturally cooled to room temperature, and the black solid was collected to obtain Co-NC nanosheets. Wherein, the drying temperature of the blast drying oven is 70° C. to 90° C.

As preferably: the drying temperature of the blast oven is 80°C.

Among them, the calcination temperature will affect the degree of graphitization of carbon nanosheets and the degree of bonding of elemental cobalt, and the temperature lower than 900 ° C is not conducive to the formation of elemental cobalt and high degree of graphitization of carbon nanosheets.

The Co-NC nanosheets prepared by the present invention have a good morphology and structure, which is conducive to the later loading of _RuSe2 particles, which can make the combination of RuSe2 particles and Co-NC nanosheets more tightly, and is conducive to the formation of more heterojunctions and exposed to increase the catalytic activity.

(3) Fresh RuSe ₂ /Co-NC nanocomposites were prepared by the hydrothermal method. Specifically, a certain amount of Co-NC was dissolved in deionized water, and after 120 minutes of ultrasonic vigorous stirring (under a 220w power ultrasonic machine) Ultrasonic treatment), add Se powder and RuCl ₃ to the above solution, stir vigorously for 10 min, then continue to add 2 mL of hydrazine hydrate (Se powder: hydrazine hydrate is 5 mg: 1 ml), use an autoclave lined with Teflon as the reaction container, transfer the obtained solution into it, raise the temperature to 120°C in a blast drying oven and keep it for 12 hours. Wash thoroughly 5-8 times, and finally dry overnight in a vacuum oven at 60°C. Among them, the mass ratio of Se powder and RuCl ₃ is 1:5-6, the mass ratio of Se powder and Co-NC is 1:0.2-1.6, preferably the mass ratio of Se powder and Co-NC is 1:0.5.

(4) The Fresh RuSe ₂ /Co-NC produced in the previous step was thermally annealed in a tube furnace to prepare RuSe ₂ /Co-NC nanocomposites, specifically, the Fresh RuSe ₂ /Co-NC was loaded on Place the crucible in a tube furnace, feed N ₂ as a protective gas, raise the temperature to the set temperature at a rate of 5°C min ^-1 and keep it for 2 hours, and then naturally cool to room temperature to obtain the final product RuSe ₂ /Co- N.C. Wherein the calcination temperature is 300°C-500°C.

As a preference: the calcination temperature is 400°C.

The present invention synthesizes the RuSe ₂ /Co-NC nano-composite material through multi-steps, first prepares a white crystalline Co, N-doped carbon nanosheet precursor by solid pyrolysis, and then synthesizes it by high-temperature annealing in a tube furnace Co-NC nanosheets, followed by uniform growth of RuSe ₂ on Co-NC nanosheets by hydrothermal method, and finally RuSe ₂ /Co-NC nanocomposites were obtained by annealing in a tube furnace. The present invention obtains optimal preparation conditions by optimizing different mass ratios of RuSe ₂ and Co-NC, and finally applies the RuSe ₂ /Co-NC nanocomposite material to electrolytic water hydrogen evolution in an alkaline environment.

The RuSe ₂ /Co-NC nanocomposite material is applied to the electrocatalytic hydrogen evolution performance test method. A three-electrode system is used. The working electrode is a glassy carbon electrode loaded with RuSe ₂ /Co-NC nanocomposite material. The counter electrode is a graphite rod electrode. The reference electrode is Hg/HgO electrode, and the electrolyte is 1mol/L KOH solution.

The technical effect that the present invention obtains is:

(1) Co-N-C nanosheets with wrinkled morphology and a large number of active sites were prepared by solid-state pyrolysis.

(2) For the first time, RuSe ₂ was uniformly loaded on the surface of Co-NC nanosheets by hydrothermal method to prepare RuSe ₂ /Co-NC nanocomposites.

(3) The effect of the amount of Co-NC added on the electrocatalytic HER performance of RuSe ₂ /Co-NC nanocomposites was studied. The heterostructure formed between _RuSe2 and Co-NC is beneficial to the improvement of electrocatalytic performance.

(4) The prepared RuSe ₂ /Co-NC-5 has excellent electrocatalytic HER performance and stability in alkaline solution.

Description of drawings

Fig. 1 is the SEM figure of embodiment 1.

Fig. 2 is the XRD figure of embodiment 1, embodiment 2, embodiment 3, embodiment 4, comparative example 1, comparative example 2, comparative example 3 and comparative example 4.

Fig. 3 is a polarization curve diagram of HER in the electrolysis of water in 1.0M KOH solution in Example 1, Example 2, Example 3 and Example 4.

Fig. 4 is a polarization curve diagram of HER in the electrolysis of water in 1.0M KOH solution of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4.

Fig. 5 is a Tafel curve diagram of the electrolyzed water HER in 1.0M KOH solution in Example 1, Example 2, Example 3 and Example 4.

Fig. 6 is a Tafel curve diagram of the electrolyzed water HER in 1.0M KOH solution of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4.

Fig. 7 is the current-time curve of water electrolysis for 17 hours at an overpotential of 26mV in Example 1.

Detailed ways

The present invention further illustrates technical characterictic of the present invention with following examples, but protection scope of the present invention is not limited to following examples.

Example 1

Preparation of 1.1mol/L KOH solution

Dissolve 5.62g KOH in 50mL ultrapure water, and after the KOH solution is completely dissolved and cooled, dilute to volume in a 100mL volumetric flask.

2. Preparation of Co and N-doped carbon nanosheets

(1) Synthesis of Co and N-doped carbon nanosheets by solid-state pyrolysis. Specifically, take 0.05g cobalt(II) acetylacetonate as the cobalt source, add it together with 8.0g urea and 0.50g glucose into 40mL deionized water, ultrasonicate and stir for 120 min at room temperature, and then get pink Transparent homogeneous solution.

(2) Place the above-mentioned beaker in a blast drying oven, set the temperature at 80°C, evaporate the pink solution to dryness completely to obtain a white crystalline precursor, put it in a crucible and transfer it to a tube furnace, and pass it into N ₂ is used as protective gas, at 5°C. The temperature was raised to 900 °C at a min ^-1 heating rate and then kept at the temperature for calcination for 5 h. After the calcination was completed, N ₂ was continued to pass through and naturally cooled to room temperature, and the black solid was collected to obtain Co-NC nanosheets.

3. Fresh RuSe ₂ /Co-NC nanocomposite material

Fresh RuSe ₂ /Co-NC nanocomposites were prepared by hydrothermal method, specifically, 5 mg Co-NC were dissolved in 35 ml deionized water, and after 120 min ultrasonic vigorous stirring, 0.0098 g Se powder and 0.0518 g RuCl ₃ were added In the above solution, after stirring vigorously for 10 minutes, continue to add 2ml of hydrazine hydrate, use a 50ml autoclave lined with Teflon as a reaction vessel, transfer the resulting solution into it, and raise the temperature to 120°C in a blast drying oven and keep it for 12h , After the reaction, the reactor was naturally cooled to room temperature, the liquid was poured out, the precipitate was collected by centrifugation, and then washed thoroughly with deionized water and ethanol for 5 to 8 times, and finally dried overnight in a vacuum oven at 60°C.

4. Preparation of RuSe ₂ /Co-NC nanocomposites

The Fresh RuSe ₂ /Co-NC produced in the previous step was thermally annealed in a tube furnace to prepare RuSe ₂ /Co-NC nanocomposites, specifically, the Fresh RuSe ₂ /Co-NC was loaded in a crucible and placed In a tube furnace, N ₂ was introduced as a protective gas, the temperature was raised to 400°C at a heating rate of 5°C min ^-1 and kept for 2 hours, and then naturally cooled to room temperature to obtain the final product RuSe ₂ /Co-NC.

application

1. Activation treatment of electrocatalyst

(1) Disperse 2 mg of catalyst and 10 μL of 5 wt % Nafion in a mixed solution containing 375 μL of ultrapure water and 125 μL of ethanol to prepare a catalyst ink. After continuous ultrasonic treatment for 20 minutes, 5 μL of uniform ink was dropped on a pre-polished glassy carbon electrode with a diameter of 3 mm, and then dried naturally at room temperature.

(2) Use a three-electrode system, the working electrode is the glassy carbon electrode whose surface is drip-coated with embodiment 1, the counter electrode is a graphite rod electrode, the reference electrode is a Hg/HgO electrode, and the electrolyte is 1mol/L KOH;

(3) Cyclic voltammetry (CV) activation: use Shanghai Chenhua DH7000 electrochemical workstation, adopt CV program, test range is -0.8～-1.6V vs. RHE, scan rate is 100mV/s, cycle 20 times, electrode reach a steady state.

2. Linear sweep voltammetry (LSV) test

After activation, switch the program to linear sweep voltammetry, the test range is -0.8～--1.6V vs. RHE, the scan rate is 5mV/s, and the electrocatalyst is at -10mA/ ^cm2 in the alkaline electrolyte. The overpotential is 26mV, as shown in Figure 3.

3. Stability test

After activation, switch the program to the chronoamperometry program, set the voltage to 26mv, and set the time to 61200s. As shown in Figure 7, the voltage of the electrocatalyst does not change much, proving its good stability.

The SEM image prepared in Example 1 is shown in FIG. 1 , and the synthesized RuSe ₂ /Co-NC nanocomposite has regular morphology. The XRD pattern is shown in Figure 2. The RuSe ₂ /Co-NC sample obtained after high-temperature annealing at 400°C has good crystallinity, and all diffraction peaks match those of crystalline RuSe ₂ and belong to metal Co. The broad peak at 25.5° is also in good agreement with the sharp diffraction peak at 44.1°, which proves the successful synthesis of RuSe ₂ /Co-NC nanocomposites.

Example 2

Compared with Example 1, the difference is: the amount of Co-N-C is changed to 0.002g in the preparation process, and other preparation methods are the same as Example 1.

The application method is the same as in Example 1, and the RuSe ₂ /Co-NC nanocomposite material prepared in Example ² is electrocatalytically decomposed water in the KOH electrolyte with a concentration of 1mol/L to prepare hydrogen, and its cathode is 10mA/cm when the current density , the overpotential is 68mV.

Example 3

Compared with Example 1, the difference is: the amount of Co-N-C is changed to 0.01g in the preparation process, and other preparation methods are the same as Example 1.

The application method is the same as in Example 1, and the RuSe ₂ /Co-NC nanocomposite material prepared in Example 3 is electrocatalyzed to decompose water in the KOH electrolyte with a concentration of 1mol/L to prepare ^hydrogen , and the cathode is 10mA/cm when the current density is 10mA/cm , the overpotential is 59mV.

Example 4

Compared with Example 1, the difference is: the amount of Co-N-C is changed to 0.015g in the preparation process, and other preparation methods are the same as Example 1.

The application method is the same as that in Example 1 and Example 4. The RuSe ₂ /Co-NC nanocomposite material prepared in Example 4 is electrocatalytically decomposed water in the KOH electrolyte with a concentration of 1mol/L to prepare ^hydrogen , and its cathode is 10mA/cm when the current density , the overpotential is 113mV.

Example 5

Compared with Example 1, the difference is that the annealing temperature is not changed to 300° C. during the synthesis of RuSe ₂ /Co-NC.

The application method is the same as in Example 1, and the RuSe ₂ /Co-NC nanosheet composite material prepared in Example 5 is electrocatalytically decomposed water in a KOH electrolyte with a concentration of 1mol/L to prepare ^hydrogen , and its cathode is 10mA/cm at a current density , the overpotential is 69mV.

Example 6

Compared with Example 1, the difference is that the annealing temperature is not changed to 500° C. during the synthesis of RuSe ₂ /Co-NC.

The application method is the same as in Example 1, and the RuSe ₂ /Co-NC nanosheet composite material prepared in Example 6 is electrocatalytically decomposed water in a KOH electrolyte with a concentration of 1mol/L to prepare ^hydrogen , and its cathode is 10mA/cm at a current density , the overpotential is 48mV.

It can be seen that the calcination temperature will affect the crystallinity of the catalyst. The catalyst obtained at a calcination temperature of 400°C has good crystallinity and catalytic activity. The performance is under the condition of a current density of 10mA cm ^-2 , and the overpotential is 26mV. When only changing When the calcination temperature is 300℃, the crystallinity of the catalyst is not high, which will affect the formation of heterostructure to a certain extent. The performance is 69mV under the condition of current density of 10mA cm ^-2 . Only changing the calcination temperature to 500 °C will cause certain agglomeration of RuSe ₂ particles supported on Co-NC nanosheets, thus affecting the catalytic activity of the catalyst. Under the calcination condition of 400 °C, not only the catalyst with good crystallinity and heterostructure can be obtained, but also more active sites of Co-NC nanosheets and RuSe2 heterostructure can be exposed, thus possessing good catalytic activity.

Comparative Example 1

Compared with Example 1, the difference is that Fresh RuSe ₂ /Co-NC is not calcined in a tube furnace during the preparation process, and is directly used as a working electrode for testing.

The application method is the same as in Example 1, and the FreshRuSe ₂ /Co-NC nanocomposite prepared in Comparative Example 1 is electrocatalyzed to decompose water in a KOH electrolyte with a concentration of 1mol/L to prepare hydrogen, and its cathode is at a current density of 10mA/cm ² , the overpotential is 111mV.

In the present invention, RuSe2 and Co-NC are combined more closely after being calcined in a tube furnace, thereby forming a heterostructure of _RuSe2 and Co-NC, thereby greatly improving the hydrogen evolution performance of the catalyst. In Comparative Example 1, Fresh _RuSe2 and Fresh RuSe2/Co-NC have little difference in hydrogen evolution performance without calcining in a tube furnace. At the same time, if only Fresh _RuSe2 is calcined to obtain the _RuSe2 material, the performance improvement is also very limited. Only the RuSe ₂ /Co-NC material obtained by Fresh RuSe2/Co-NC after calcination has a huge improvement in the hydrogen evolution performance, which also shows that the catalytic performance of the present invention benefits from the calcination for a while in RuSe ₂ and Co-NC heterogeneous structure formed between them.

Comparative Example 2

Compared with Example 1, the difference is that the Co-N-C nanoblock prepared by replacing the raw material is used directly as a working electrode.

The application method is the same as in Example 1, and the Co-NC material prepared in Comparative Example 2 is electrocatalytically decomposed water to prepare hydrogen in a KOH electrolyte with a concentration of 1mol/L. When the current density of the cathode is 10mA/cm ² , the overpotential is 289mV.

Compared with Example 1, the difference is that dicyandiamide is used as a nitrogen source and a carbon source, and cobalt nitrate is used as a cobalt source, and other conditions are the same, and finally a massive cobalt-nitrogen-doped carbon structure is obtained, and a nanosheet structure cannot be obtained. .

Comparative Example 3

Compared with Example 1, the difference is that Co-NC is not added during the synthesis of RuSe ₂ .

The application method is the same as that in Example 1, and the _RuSe2 material prepared in Comparative Example 3 is prepared by electrocatalytically decomposing water in a KOH electrolyte with a concentration of 1mol/L to prepare hydrogen. When the current density of the cathode is 10mA/cm ² , the overpotential is 90mV .

Comparative Example 4

Compared with Example 1, the difference is that Co-NC is not added during the synthesis of FreshRuSe ₂ , and the annealing operation is not performed in a tube furnace at 400°C.

The application method is the same as in Example 1, and the _FreshRuSe2 material prepared in Comparative Example 4 is electrocatalytically decomposed water in a KOH electrolyte with a concentration of 1mol/L to prepare hydrogen. When the current density of the cathode is 10mA/cm ² , the overpotential is 113mV .

Claims (8)

1. RuSe₂The preparation method of the/Co-N-C nano composite material is characterized by comprising the following specific steps:

(1) Taking cobalt acetylacetonate (II) as a cobalt source, dissolving the cobalt source, urea and glucose into deionized water, and stirring to obtain a pink transparent uniform solution;

(2) Putting the solution obtained in the step (1) in a drying box, completely evaporating pink transparent uniform solution to dryness to obtain a white crystalline precursor, containing the white crystalline precursor by using a crucible, transferring the white crystalline precursor to a tubular furnace, and introducing N₂Heating to 900 deg.C as protective gas, calcining, and introducing N₂Naturally cooling to room temperature, and collecting black solids to obtain Co-N-C nanosheets;

(3) Preparation of Fresh RuSe by hydrothermal method₂Co-N-C nanocomposites: dispersing Co-N-C nanosheets in deionized water, and ultrasonically and violently stirring to obtain Se powder and RuCl₃Adding into the solution, stirring vigorously, adding hydrazine hydrate, transferring the obtained solution into a high-pressure reaction kettle serving as a reaction container, heating for reaction, naturally cooling the reaction kettle to room temperature after the reaction is finished, pouring out the liquid, centrifuging, collecting the precipitate, cleaning, and drying to obtain Fresh RuSe₂/Co-N-C；

(4) Fresh Ruse₂Thermal annealing treatment of/Co-N-C in a tube furnace to produce RuSe₂Co-N-C nanocomposites: fresh Ruse₂the/Co-N-C is loaded in a crucible and arranged in a tube furnace, and N is introduced₂As protective gas, the temperature is raised to 300 to 500 ℃ for calcination, and the calcined product is naturally cooledCooling to room temperature to obtain the final product RuSe₂/Co-N-C。

2. The Ruse according to claim 1₂The preparation method of the/Co-N-C nano composite material is characterized in that the mass ratio of cobalt acetylacetonate (II) to urea in the step (1) is 1:150 to 200.

3. The Ruse according to claim 1₂The preparation method of the/Co-N-C nano composite material is characterized in that the mass ratio of cobalt acetylacetonate (II) to glucose in the step (1) is 1:10 to 15.

4. The RuSe of claim 1₂The preparation method of the/Co-N-C nano composite material is characterized in that Se powder and RuCl are used in the step (3)₃The mass ratio of (1): 5-6, the mass ratio of the Se powder to the Co-N-C is 1.2-1.6.

5. The Ruse according to claim 1₂The preparation method of the/Co-N-C nano composite material is characterized in that the calcination time in the step (2) is 5 hours.

6. The Ruse according to claim 1₂The preparation method of the/Co-N-C nano composite material is characterized in that the temperature rise reaction condition in the step (3) is 120 ℃ and is kept for 12 hours.

7. The RuSe of claim 1₂The preparation method of the/Co-N-C nano composite material is characterized in that the calcining temperature in the step (4) is 400 ℃, and the calcining time is 2 hours.

8. RuSe prepared by the method of any one of claims 1 to 7₂Use of a/Co-N-C nanocomposite, wherein the RuSe is present₂the/Co-N-C nano composite material is used for electrocatalytic hydrogen evolution under alkaline conditions.

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