CN115029709A - Cobalt-nickel metal sulfide bifunctional electrocatalyst and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the field of electrocatalyst preparation and application, in particular to a cobalt-nickel metal sulfide bifunctional electrocatalyst and a preparation method and application thereof. First, the blank nickel foam was placed in an organic solvent and a dilute acid solution to ultrasonically clean the surface impurities of the nickel foam, and then the treated nickel foam was put into the cobalt source aqueous solution for reaction. After the reaction, the Co@NF was washed and dried. materials; Co@NF was then calcined with a sulfur source, and finally CoNi ₂ S ₄ /NiS _x @NF electrocatalyst was obtained. The invention obtains a bifunctional electrocatalyst with nanowire shape by controlling the calcination temperature and time, increases the electrochemically active surface area, and has high activity and good stability for electrocatalytic hydrogen evolution and oxygen evolution reactions. The catalyst exhibits excellent hydrogen and oxygen evolution performance in KOH.

Description

A kind of cobalt-nickel metal sulfide bifunctional electrocatalyst and preparation method and application thereof

technical field

The invention belongs to the field of electrocatalyst preparation and application, in particular to a cobalt-nickel metal sulfide bifunctional electrocatalyst and a preparation method and application thereof.

Background technique

A sustainable route to renewable energy that alleviates reliance on traditional fossil fuel combustion has attracted widespread attention. Electrochemical energy conversion via water splitting holds great potential. It is well known that both the cathodic hydrogen evolution reaction (HER) and the anodic oxygen evolution reaction (OER) are related to water splitting and both require electrocatalysts to ensure practical rates. So far, noble metal-based materials have been widely used as efficient electrocatalysts. However, high cost and scarcity limit their large-scale applications. Therefore, it is very important to develop inexpensive and abundant non-noble metal electrocatalysts. In the same electrolyte, most non-noble metal electrocatalysts are highly active only for HER or OER. In this context, there is an increasing effort to develop efficient, stable, and inexpensive electrocatalysts for HER and OER bifunctionality.

First-row transition metals (Mn, Fe, Co, and Ni) and their oxides, phosphides, sulfides, and selenides are promising alternatives to these noble metals due to their cost-effectiveness and intrinsic activity. However, the electrochemical performance and structural stability of single-component sulfides, phosphides, and selenides need to be further enhanced compared to catalysts in industrial production.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a cobalt-nickel metal sulfide bifunctional electrocatalyst and a preparation method thereof, and apply it to decompose water under alkaline conditions to prepare hydrogen and oxygen, with high catalytic activity and good stability.

Technical scheme of the present invention: The preparation method of the cobalt-nickel metal sulfide bifunctional electrocatalyst provided by the present invention is as follows: firstly, pretreating the foamed nickel, then dispersing the cobalt source and reducing agent in deionized water, fully stirring, The treated nickel foam was placed in the dispersion, loaded into a stainless steel autoclave, reacted at high temperature, and the product was washed with deionized water and ethanol and vacuum-dried to obtain Co@NF material; the sulfur source and Co@NF were placed in tubes respectively. The upstream and downstream of the furnace were then calcined in a tube furnace, and finally the product was washed and vacuum dried to obtain the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst.

The specific process is:

(1) Foamed nickel (NF) was used as the nickel source, cleaned by sonication in dilute HCl, distilled water, and acetone, and finally dried overnight.

(2) Co(NO ₃ ) ₂ ·6H ₂ O was used as cobalt source, and NH ₃ F and CH ₄ N ₂ O were used as surface modifier and precipitant to dissolve in deionized water, and stir well until they were completely dispersed.

The mass ratio of Co(NO ₃ ) ₂ ·6H ₂ O, NH ₃ F and CH ₄ N ₂ O is: 0.50 to 6.00: 0.05 to 0.50: 0.10 to 2.50.

(3) placing the dispersion liquid obtained in step (2) in a polytetrafluoroethylene lining, then adding the pretreated nickel foam to the dispersion liquid, putting it into a stainless steel autoclave, and then putting it into a blast drying oven heating.

In the blast drying oven, the temperature is set to 130°C, and the time is set to 5-20h.

(4) The product obtained in step (3) was washed with deionized water and ethanol, and dried in a vacuum drying oven to obtain Co@NF.

In a vacuum drying oven, the temperature was set to 60°C and the time was set to 12h.

(5) The CH ₄ N ₂ S as the sulfur source and the Co@NF were placed in the upstream and downstream of the N ₂ atmosphere tube furnace, respectively, and calcined at a certain temperature for a period of time.

The distance between the upstream and downstream of the tube furnace: 3 to 5 cm.

The calcination temperature in the tube furnace is: 350℃～500℃, and the calcination time is: 1h～4h.

The mass ratio of CH ₄ N ₂ S to the area of nickel foam is 2:1 g/cm ² to 4:1 g/cm ² .

(6) washing and drying the product obtained in step (5) to obtain the final product CoNi ₂ S ₄ /NiS _x @NF electrocatalyst.

The present invention selects suitable cobalt source, nickel source, surface modifier and precipitant, controls the mass ratio of Co(NO ₃ ) ₂ ·6H ₂ O, NH ₃ F and CH ₄ N ₂ O, as well as the temperature and The Co@NF electrocatalyst was synthesized in time; then the appropriate sulfur source was selected, the distance between CH ₄ N ₂ S and Co@NF, and the calcination temperature and time were controlled to prepare the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst.

The invention also provides the application of a CoNi ₂ S ₄ /NiS _x @NF electrocatalyst as a working electrode to electrolyze water to prepare hydrogen or oxygen under alkaline conditions.

The CoNi ₂ S ₄ /NiS _x @NF electrocatalyst is applied to the electrocatalytic hydrogen evolution and oxygen evolution performance test method. A three-electrode system is used. The working electrode is the electrode loaded with CoNi ₂ S ₄ /NiS _x @NF, and the counter electrode is 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) The catalyst provided by the present invention is a CoNi ₂ S ₄ /NiS _x @NF electrocatalyst made of a composite material in which cobalt-nickel mixed metal sulfide is supported on foamed nickel. The synthesis method is novel, the conditions are simple, and the operation is easy and fast. High efficiency, energy saving, environmental protection and easy industrial production;

(2) The CoNi ₂ S ₄ /NiS _x @NF electrocatalyst provided by the present invention has a regular nanowire morphology after controlling the calcination temperature and time, which increases the electrochemically active surface area, and is effective for the electrocatalytic hydrogen evolution and oxygen evolution reactions. Has a high degree of activity and good stability;

(3) The CoNi ₂ S ₄ /NiS _x @NF electrocatalyst provided by the present invention has high catalytic hydrogen evolution activity and good stability in alkaline electrolyte, and electrocatalytic decomposition in KOH electrolyte with a concentration of 1 mol/L Hydrogen production from water, using CoNi ₂ S ₄ /NiS _x @NF electrocatalyst as the working electrode, the overpotential is only 77mV when the current density is -10mA/cm ² , which shows excellent catalytic performance and excellent catalytic performance for the hydrogen evolution reaction of water electrolysis. stability.

(4) The CoNi ₂ S ₄ /NiS _x @NF electrocatalyst provided by the present invention has high catalytic oxygen evolution activity and good stability in alkaline electrolyte, and electrocatalyzes in KOH electrolyte with a concentration of 1 mol/L Decomposition of water to produce oxygen, using CoNi ₂ S ₄ /NiS _x @NF electrocatalyst as the working electrode, the overpotential is only 241mV when the current density is 10mA/cm ² , showing excellent catalytic performance for the oxygen evolution reaction of water electrolysis and stability.

Description of drawings

1 is the XRD patterns of CoNi ₂ S ₄ /NiS _x @NF obtained in Example 1 of the present invention and Co@NF and NF obtained in Comparative Examples 1-2.

2 is a SEM image of CoNi ₂ S ₄ /NiS _x @NF obtained in Example 1 of the present invention.

3 is a SEM image of CoNi ₂ S ₄ /NiS _x @NF obtained in Comparative Example 3 of the present invention.

4 is a graph showing the polarization curves of CoNi ₂ S ₄ /NiS _x @NF obtained in Examples 1-4 of the present invention, Example 10 and Comparative Example 3 for electrolysis of water HER in a 1.0 MKOH solution.

FIG. 5 is a polarization curve diagram of the OER of electrolyzed water in 1.0 MKOH solution of CoNi ₂ S ₄ /NiS _x @NF obtained in Examples 1-4, Example 10 and Comparative Example 3 of the present invention.

FIG. 6 is a polarization curve diagram of the electrolyzed water HER of CoNi ₂ S ₄ /NiS _x @NF obtained in Example 1, Example 5-9 and Comparative Example 1-2 of the present invention in a 1.0 MKOH solution.

FIG. 7 is a polarization curve diagram of the OER of electrolyzed water obtained by CoNi ₂ S ₄ /NiS _x @NF obtained in Example 1, Example 5-9 and Comparative Example 1-2 of the present invention in a 1.0 MKOH solution.

Detailed ways

The technical features of the present invention are further described below with reference to the accompanying drawings and embodiments, but the protection scope of the present invention is not limited thereto.

Example 1

1. Preparation of NF

Foamed nickel (NF) (3 × 5 cm) was cleaned in HCl (3 M), distilled water and acetone by sonication for 15 min each, and finally dried at 60 °C overnight.

2. Preparation of Co(NO ₃ ) ₂ ·6H ₂ O dispersion

Measure 70ml of deionized water with a measuring cylinder and pour it into a beaker, add 1.7g Co(NO ₃ ) ₂ ·6H ₂ O, 0.1g NH ₃ F and 0.7g CH ₄ N ₂ O, and stir well for 0.5h.

3. Preparation of Co@NF

Slowly add the Co(NO ₃ ) ₂ ·6H ₂ O dispersion into the PTFE liner, then put NF (3×5cm) into the PTFE liner, and finally put it into a stainless steel autoclave, It was placed in a blast drying oven, the temperature was set to 130 °C, and the drying time was set to 20 h. After the time was over, the product was cooled to room temperature, and the product was washed and dried to obtain Co@NF.

4. Preparation of CoNi ₂ S ₄ /NiS _x @NF Electrocatalyst

Weigh 4g CH ₄ N ₂ S into a crucible, and place the product Co@NF (1×1 cm) in another crucible. The area ratio of CH ₄ N ₂ S to foamed nickel is 4:1 g/cm ² , Place the two crucibles on the upstream and downstream of the _N2 atmosphere tube furnace respectively, the distance between the two crucibles is set to 3cm, the control heating rate is set to 1.4°C/min, the calcination temperature is 450°C, the calcination time is 2h, the calcination is completed, The final product CoNi ₂ S ₄ /NiS _x @NF electrocatalyst was obtained.

The XRD pattern of the CoNi ₂ S ₄ /NiS _x @NF prepared in Example 1 is shown in Fig. 1 and the SEM picture is shown in Fig. 2. It can be seen from the XRD and SEM patterns that the prepared CoNi ₂ S ₄ / The XRD characteristic peaks of NiS _x @NF electrocatalyst are sharp and obvious, with characteristic peaks of CoNi ₂ S ₄ , NiS and NiS ₂ , and the SEM morphology is regular nanowire-like.

Example 2

Compared with Example 1, the difference is: the preparation of Co(NO ₃ ) ₂ ·6H ₂ O ₂ dispersion. Measure 70ml of deionized water with a measuring cylinder and pour it into a beaker, add 0.9g Co(NO ₃ ) ₂ ·6H ₂ O, 0.07g NH ₃ F and 0.4g CH ₄ N ₂ O, and stir well for 0.5h. Other preparation methods are the same as in Example 1.

Example 3

Compared with Example 1, the difference is: the preparation of Co(NO ₃ ) ₂ ·6H ₂ O dispersion. Measure 70ml of deionized water with a measuring cylinder and pour it into a beaker, add 3.5g Co(NO ₃ ) ₂ ·6H ₂ O, 0.3g NH ₃ F and 1.4g CH ₄ N ₂ O, and stir well for 0.5h. Other preparation methods are the same as in Example 1.

Example 4

Compared with Example 1, the difference is: the preparation of Co(NO ₃ ) ₂ ·6H ₂ O dispersion. Measure 70ml of deionized water with a measuring cylinder and pour it into a beaker, add 5.2g Co(NO ₃ ) ₂ ·6H ₂ O, 0.4g NH ₃ F and 2.2g CH ₄ N ₂ O, and stir well for 0.5h. Other preparation methods are the same as in Example 1.

Example 5

Compared with Example 1, the difference is: the preparation of Co@NF. The temperature in the blast drying oven was set to 130 °C, and the drying time was set to 5 h. Other preparation methods are the same as in Example 1.

Example 6

Compared with Example 1, the difference is: the preparation of CoNi ₂ S ₄ /NiS _x @NF electrocatalyst. Two crucibles were placed upstream and downstream of the _N2 atmosphere tube furnace respectively, and the distance between the two crucibles was set to 5 cm. Other preparation methods are the same as in Example 1.

Example 7

Compared with Example 1, the difference is: the preparation of CoNi ₂ S ₄ /NiS _x @NF electrocatalyst. The calcination temperature of the tube furnace was set at 350°C. Other preparation methods are the same as in Example 1.

Example 8

Compared with Example 1, the difference is: the preparation of CoNi ₂ S ₄ /NiS _x @NF electrocatalyst. The calcination temperature of the tube furnace was set at 400°C. Other preparation methods are the same as in Example 1.

Example 9

Compared with Example 1, the difference is: the preparation of CoNi ₂ S ₄ /NiS _x @NF electrocatalyst. The calcination temperature of the tube furnace was set at 500°C. Other preparation methods are the same as in Example 1.

Example 10

Compared with Example 1, the difference is: the preparation of CoNi ₂ S ₄ /NiS _x @NF electrocatalyst. The ratio of the mass of CH ₄ N ₂ S to the area of nickel foam was 2:1 g/cm ² . Other preparation methods are the same as in Example 1.

Comparative Example 1

Compared with Example 1, the difference is that there is no step 4. The preparation method of steps 1-3 is the same as that of Example 1. It can be seen from the polarization curve diagram that the Co@NF prepared without calcination has large hydrogen evolution and oxygen evolution overpotentials.

Comparative Example 2

Compared with Example 1, the difference is that steps 2-4 are not included, but only the NF preprocessed in step 1. It can be seen from the polarization curve that the pretreated NF has a large overpotential for hydrogen evolution and oxygen evolution.

Comparative Example 3

Compared with Example 1, the difference is: the preparation of Co(NO ₃ ) ₂ ·6H ₂ O dispersion. _NH3F and _CH4N2O species _were not added. Other preparation methods are the same as in Example 1. It can be seen from the polarization curve diagram and SEM that without the addition of NH ₃ F and CH ₄ N ₂ O species, the cobalt source cannot be supported on the foamed nickel, and the prepared CoNi ₂ S ₄ /NiS _x @NF has a Both hydrogen evolution and oxygen evolution have large overpotentials and irregular nanowire-like morphology.

Application example 1

1. Activation treatment of electrocatalyst

(1) A three-electrode system was used, the working electrode was the CoNi ₂ S ₄ /NiS _x @NF electrode in Example 1, the counter electrode was a graphite rod electrode, the reference electrode was a Hg/HgO electrode, and the electrolyte was 1 mol/L KOH.

(2) Cyclic voltammetry (CV) activation. ①HER: Using Shanghai Chenhua DH7000 electrochemical workstation, using CV program, the test range is -0.5 ~ -1.6V vs. RHE, the scan rate is 50mV/s, and the electrode reaches a stable state after 20 cycles. ②OER: Using Shanghai Chenhua DH7000 electrochemical workstation, using CV program, the test range is 0-0.8V vs. RHE, the scanning speed is 50mV/s, and the electrode reaches a stable state after 20 cycles.

2. Linear sweep voltammetry (LSV) test

(1) HER: After activation, the switching procedure is linear sweep voltammetry procedure, the test range is -0.5～-1.6Vvs.RHE, the sweep rate is 5mV/s, and the electrocatalyst in alkaline electrolyte is at -10mA/cm ² , the overpotential is 77mV, as shown in Figures 4 and 6.

(2) OER: After activation, the switching procedure is linear sweep voltammetry procedure, the test range is 0-0.8V vs. RHE, the sweep rate is 5mV/s, and the electrocatalyst in alkaline electrolyte is at 10mA/ ^cm2 , the overpotential is 241mV, as shown in Figures 5 and 7.

Application example 2

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 2 electrocatalytically splits water to produce hydrogen in KOH electrolyte with a concentration of 1 mol/L, and the current density is -10 mA/cm ² , an electrocatalyst with an overpotential of 97 mV.

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 2 electrocatalytically decomposes water to produce oxygen in KOH electrolyte with a concentration of 1 mol/L, and when the current density is 10 mA/cm ² , an electrocatalyst with an overpotential of 392 mV.

Application example 3

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 3 electrocatalytically decomposes water to produce hydrogen in KOH electrolyte with a concentration of 1 mol/L, and the current density is -10 mA/cm ² , an electrocatalyst with an overpotential of 79 mV.

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 3 electrocatalytically decomposes water to produce oxygen in KOH electrolyte with a concentration of 1 mol/L, and when the current density is 10 mA/cm ² , an electrocatalyst with an overpotential of 283 mV.

Application example 4

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 4 electrocatalytically decomposes water to produce hydrogen in KOH electrolyte with a concentration of 1 mol/L, and the current density is -10 mA/cm ² , an electrocatalyst with an overpotential of 108 mV.

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 4 electrocatalytically decomposes water to produce oxygen in KOH electrolyte with a concentration of 1 mol/L, and when the current density is 10 mA/cm ² , an electrocatalyst with an overpotential of 349 mV.

Application example 5

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 5 was electrocatalytically decomposed water to produce hydrogen in KOH electrolyte with a concentration of 1 mol/L, and the current density was -10 mA/cm ² , an electrocatalyst with an overpotential of 198 mV.

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 5 electrocatalytically decomposes water to produce oxygen in KOH electrolyte with a concentration of 1 mol/L, and when the current density is 10 mA/cm ² , an electrocatalyst with an overpotential of 347 mV.

Application example 6

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 6 was electrocatalytically decomposed water to produce hydrogen in KOH electrolyte with a concentration of 1 mol/L, and the current density was -10 mA/cm ² , an electrocatalyst with an overpotential of 125 mV.

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 6 electrocatalytically decomposes water to produce oxygen in KOH electrolyte with a concentration of 1 mol/L, and when the current density is 10 mA/cm ² , an electrocatalyst with an overpotential of 270 mV.

Application example 7

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 7 was electrocatalytically decomposed water to produce hydrogen in KOH electrolyte with a concentration of 1 mol/L, and the current density was -10 mA/cm ² , an electrocatalyst with an overpotential of 112 mV.

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 7 electrocatalytically decomposes water to produce oxygen in KOH electrolyte with a concentration of 1 mol/L, and when the current density is 10 mA/cm ² , an electrocatalyst with an overpotential of 355 mV.

Application example 8

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 8 electrocatalytically decomposes water to produce hydrogen in KOH electrolyte with a concentration of 1 mol/L, and the current density is -10 mA/cm ² , an electrocatalyst with an overpotential of 82 mV.

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 8 electrocatalytically decomposes water to produce oxygen in KOH electrolyte with a concentration of 1 mol/L, and when the current density is 10 mA/cm ² , an electrocatalyst with an overpotential of 351 mV.

Application example 9

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 9 electrocatalytically decomposes water to produce hydrogen in KOH electrolyte with a concentration of 1 mol/L, and the current density is -10 mA/cm ² , an electrocatalyst with an overpotential of 145 mV.

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 9 electrocatalytically decomposes water to produce oxygen in KOH electrolyte with a concentration of 1 mol/L, and when the current density is 10 mA/cm ² , an electrocatalyst with an overpotential of 392 mV.

Application example 10

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 10 electrocatalytically decomposes water to produce hydrogen in KOH electrolyte with a concentration of 1 mol/L, and the current density is -10 mA/cm ² , an electrocatalyst with an overpotential of 87 mV.

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Example 10 electrocatalytically decomposes water to produce oxygen in KOH electrolyte with a concentration of 1 mol/L, and when the current density is 10 mA/cm ² , an electrocatalyst with an overpotential of 290 mV.

Application example 11

As shown in Application Example 1, the Co@NF electrocatalyst prepared in Comparative Example 1 electrocatalytically decomposes water to produce hydrogen in a KOH electrolyte with a concentration of 1 mol/L. When the current density is -10 mA/ ^cm2 , the overpotential is 206mV electrocatalyst.

As shown in Application Example 1, the Co@NF electrocatalyst prepared in Comparative Example 1 electrocatalyzed water splitting to produce oxygen in KOH electrolyte with a concentration of 1 mol/L, and the overpotential was 438 mV at a current density of 10 mA/cm ² electrocatalyst.

Application example 12

As shown in Application Example 1, the NF electrocatalyst prepared in Comparative Example 2 electrocatalytically decomposes water to prepare hydrogen in a KOH electrolyte with a concentration of 1 mol/L. When the current density is -10mA/ ^cm2 , the overpotential is 224mV. Electrocatalyst.

As shown in Application Example 1, the NF electrocatalyst prepared in Comparative Example ² electrocatalytically decomposes water to prepare oxygen in KOH electrolyte with a concentration of 1 mol/L. When the current density is 10 mA/cm catalyst.

Application example 13

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Comparative Example 3 was electrocatalytically decomposed water to produce hydrogen in KOH electrolyte with a concentration of 1 mol/L, and the current density was -10 mA/cm. ² , the electrocatalyst with an overpotential of 180 mV.

As shown in Application Example 1, the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst prepared in Comparative Example 3 electrocatalytically decomposes water to produce oxygen in KOH electrolyte with a concentration of 1 mol/L, and the current density is 10 mA/cm ² , an electrocatalyst with an overpotential of 330 mV.

The above-mentioned specific embodiments describe in detail the technical solutions and beneficial effects of the present invention. It should be understood that the above-mentioned embodiments are only the most preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, additions and equivalent replacements made within the scope shall be included in the protection scope of the present invention.

Claims (9)

1. A cobalt-nickel metal sulfide bifunctional electrocatalyst, characterized in that the electrocatalyst is a material with regular nanowires; composed of CoNi ₂ S ₄ , NiS _x (x=1,2) and nickel foam NF composition. 2. a preparation method of cobalt-nickel metal sulfide bifunctional electrocatalyst, it is characterized in that, described preparation method is: first carry out pretreatment to foam nickel, then cobalt source and reducing agent are dispersed in deionized water, fully stir , the pretreated nickel foam was placed in the dispersion, loaded into a stainless steel autoclave, reacted at high temperature, the product was washed with deionized water and ethanol and dried in vacuum to obtain Co@NF material; the sulfur source and Co@NF were separated It was placed upstream and downstream of the tube furnace, then calcined in the tube furnace, and finally the product was washed and vacuum-dried to obtain the CoNi ₂ S ₄ /NiS _x @NF electrocatalyst. 3. the preparation method of cobalt-nickel metal sulfide bifunctional electrocatalyst according to claim 2, is characterized in that, the concrete steps of described preparation method are as follows: (1) with nickel foam (NF) as nickel source, it is successively cleaned by ultrasonic treatment in HCl, distilled water and acetone, and dried overnight; (2) Co(NO ₃ ) ₂ ·6H ₂ O was used as the cobalt source, and NH ₃ F and CH ₄ N ₂ O were used as the surface modifier and the precipitant to dissolve in deionized water, respectively, and fully stirred until it was completely dispersed; the obtained dispersion The liquid is placed in a polytetrafluoroethylene lining, and the pretreated nickel foam in step (1) is added therein, put into a stainless steel autoclave, and then heated in a blast drying oven; the obtained product is heated with deionized water and ethanol. Washed and dried in a vacuum drying oven to obtain Co@NF; (3) The CH ₄ N ₂ S as the sulfur source and Co@NF were placed in the upstream and downstream of the N ₂ atmosphere tube furnace respectively, and then calcined at high temperature, and the product was washed and dried to obtain the final product CoNi ₂ S ₄ /NiS _x @NF electric catalyst. 4. The preparation method of cobalt-nickel metal sulfide bifunctional electrocatalyst according to claim 3, wherein in step (2), Co(NO ₃ ) ₂ .6H ₂ O, NH ₃ F and CH ₄ N ₂ The mass ratio of O is: 0.50-6.00:0.05-0.50:0.10-2.50. 5. The preparation method of cobalt-nickel metal sulfide bifunctional electrocatalyst according to claim 3, characterized in that, in step (2), the heating time in the blast drying oven: 5～20h, and the temperature is set to 130°C. 6 . The method for preparing a cobalt-nickel metal sulfide bifunctional electrocatalyst according to claim 3 , wherein the distance between the upstream and downstream of the tube furnace in step (3) is 3 to 5 cm. 7 . 7. the preparation method of cobalt-nickel metal sulfide bifunctional electrocatalyst according to claim 3, is characterized in that, in step (3), in the tube furnace, the calcination temperature is: 350 ℃～500 ℃, and the calcination time is: 1h ~ 4h. 8. the preparation method of cobalt-nickel metal sulfide bifunctional electrocatalyst according to claim 3, is characterized in that, in step (3), the area ratio of _CH4N2S quality and foam nickel is ₂ :1g/ ^cm2 ~4:1 g/cm ² . 9. an application of the cobalt-nickel metal sulfide bifunctional electrocatalyst according to claim 1, wherein the cobalt-nickel metal sulfide bifunctional electrocatalyst is used for electrocatalytic hydrogen evolution and electrocatalysis under alkaline conditions Oxygen evolution.

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