CN111659421B - V-doped Ni 3 S 2 Nano-sheet/nano-rod composite structure electrocatalyst and preparation method thereof - Google Patents

Abstract

V-doped Ni ₃ S ₂ An electrocatalyst with a nano-sheet/nano-rod composite structure and a preparation method thereof, wherein a hydrothermal-solvothermal method is adopted to synthesize V-doped Ni with the nano-sheet/nano-rod composite structure on the surface of foamed nickel ₃ S ₂ A material. First VCl ₃ Adding urea into deionized water at the same time, stirring to obtain a uniform solution A, immersing clean foam nickel into the solution A for hydrothermal reaction, and cleaning and drying to obtain a precursor of the NiV-LDH nanosheet array; then immersing the precursor of the NiV-LDH nanosheet array into a mixed solution B formed by ethanol and tert-dodecyl mercaptan solvent for solvothermal reaction, cleaning and drying to obtain the V-doped Ni ₃ S ₂ An electrocatalyst with a nano-sheet/nano-rod composite structure. The method has the characteristics of mild reaction conditions, simple and convenient operation, easy control, no need of harsh reaction conditions and easy mass production.

Description

A V-doped Ni3S2 nanosheet/nanorod composite electrocatalyst and its preparation method

technical field

The invention relates to an electrocatalyst and a preparation method thereof, in particular to a V- _{doped Ni3S2} nanosheet/nanorod composite structure electrocatalyst and a preparation method thereof.

Background technique

"Energy crisis" and "environmental pollution" are two major problems that plague human society today. Seeking and developing clean and sustainable energy is regarded as one of the effective ways to solve these two problems. Hydrogen is a recognized carrier of a new generation of clean and sustainable energy, and is expected to become an important part of the future energy landscape of mankind. However, there is no hydrogen on Earth, and we must first consider how to produce it in an environmentally friendly way. At present, there are three main routes for industrial hydrogen production, namely methane steam reforming, coal gasification process and hydrogen production by electrolysis of water. The first two preparation methods still consume non-renewable fossil fuels and emit carbon dioxide, which is clearly not what we expect. The raw material for hydrogen production from water electrolysis is water, which is abundant in nature and renewable, providing the possibility for sustainable hydrogen production; the electricity it needs can be converted from renewable energy (such as wind energy, water energy, etc.) ; The products of hydrogen production from water electrolysis are hydrogen and oxygen, which will not cause secondary pollution to the environment. Therefore, electrolysis of water for hydrogen production has become more and more popular as an environmentally friendly hydrogen production route. One of the keys to the development of the technology of electrolysis of water for hydrogen production is the innovation of catalytic materials. At present, the most active hydrogen production catalysts are noble metal platinum-based materials. However, the extremely low earth abundance and extremely high price of noble metal platinum restrict the wide application of such catalysts. Therefore, the research core of catalytic materials for hydrogen production from water splitting is to develop highly active and inexpensive catalytic materials without precious metals to maximize the efficiency of water splitting and reduce the cost of water splitting.

Transition metal sulfides have always been considered as a feasible solution to replace precious metals and their oxide catalysts, because of their rich phase structure, good oxygen evolution stability, and low cost. Among transition metal sulfides, Ni-based catalysts are abundant in reserves, have good electron transfer and acid-base resistance, and are favored by researchers. Among them, Ni ₃ S ₂ in the metallic state exhibits the best electrocatalytic activity. Since Ni ₃ S ₂ has a Ni-Ni bond network system throughout the entire structure, and its electronic structure is similar to that of metals, its electrical conductivity is relatively high. Ni ₃ S ₂ catalyst materials have in-depth research value and significance.

The Chinese patent with the application number CN201910304694.0 "A kind of nanoparticle of Au@ _Ni3S2 core _- shell structure with a single crystal shell layer and its preparation method", the synthesis technology is first to prepare Au under the condition of passing argon gas Then, the Au@Ni ₃ S ₂ core-shell nanoparticle solution was obtained by seed growth method in 1-dodecanethiol solution, and finally the final product was obtained by washing and centrifuging with chloroform and acetone solution. The synthetic technique has cumbersome steps, complicated operation, difficult control of reaction conditions, and many influencing factors in the reaction process.

The Chinese patent with the application number CN201910106207.X "a preparation method of a micro-flower ball-shaped high-performance bifunctional electrocatalyst FeOOH/Ni ₃ S ₂ for total water splitting", the synthesis technology adopts the method of solvothermal-electrochemical deposition, and the reaction conditions It is relatively difficult to control, and the current and voltage during the electrochemical deposition process are unstable, which can easily lead to uneven preparation of materials and affect their morphology and performance.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst with mild reaction conditions in the preparation process, simple operation and easy control, unique product structure and excellent electrochemical performance. Preparation.

To achieve the above object, the technical scheme adopted in the present invention is:

1) Weigh 80-120 mg of vanadium chloride (VCl ₃ ) and 60-80 mg of urea into 20-30 mL of deionized water at the same time, and magnetically stir to obtain a uniform solution A;

2) Transfer solution A to a 50 mL reaction kettle, add clean nickel foam and immerse it in solution A for hydrothermal reaction at 130-180° C. for 8-12 hours, wash and dry to obtain NiV-LDH nanosheet array precursor;

3) Then add 20-30 mL of mixed solution B formed by ethanol solvent and tert-dodecanethiol solvent into the 50 mL reaction kettle, and immerse it in the NiV-LDH nanosheet array precursor, and place it at 120-200 ℃ for solvothermal reaction for 3-6 h , washed and dried to obtain V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst.

In the step 2), the foamed nickel area is 1cm*5cm.

The mixed solution B in the step 3) is that the volume ratio of ethanol to tert-dodecanethiol is 5:1 to 10:1.

The V-doped Ni ₃ S ₂ nano-sheet/nano-rod composite structure electrocatalyst prepared by the above preparation method is characterized in that: a nano-sheet/nano-rod composite structure V-doped Ni ₃ S ₂ material is synthesized on the surface of the nickel foam.

The electrocatalyst has a hydrogen production overpotential of 146mV at a current density of 10mA cm ^-2 , a hydrogen production overpotential of 259mV at a current density of 100mA cm ^-2 , and a hydrogen production overpotential of 1000mA cm ^-2 at a current density of 1000mA cm-2. The hydrogen production overpotential is 503mV; under the current density of 100mA cm ^-2 , the oxygen production overpotential is 328mV, showing a relatively excellent electrochemical hydrogen production and oxygen production activity.

Compared with the prior art, the inventive method has the following characteristics:

1) The present invention adopts a hydrothermal-solvothermal method to prepare a synthetic product, which has mild reaction conditions and a simple synthetic route, and does not require large-scale equipment and harsh reaction conditions. The whole reaction process is simple, the prepared product has high yield, uniform morphology, low cost, and is suitable for large-scale production.

2) In the present invention, the size of the foamed nickel clipping area determines the amount of nickel source added, and the synthesis of the NiV-LDH nanosheet array structure can be realized only by controlling the ratio of the nickel source to the vanadium source within a certain range.

3) The present invention selects a mixed solvent of ethanol and tert-dodecanethiol in the solvothermal reaction, because tert-dodecanethiol has a sulfhydryl functional group (-SH), which can be used as a sulfur source and also as a solvent to participate in the reaction.

4) In the present invention, by adjusting the ratio of ethanol and tert-dodecanethiol solvent to control the existing state and morphology of nickel sulfide, the synthesis of V-doped Ni ₃ S ₂ material with nanosheet/nanorod composite structure is promoted. .

5) The V-doped Ni ₃ S ₂ nano-sheet/nano-rod composite structure electrocatalyst prepared by the present invention has a unique structure, showing the morphology of the V-doped Ni ₃ S ₂ nano-sheet/nano-rod composite structure, and the nano-sheet The lush nanorod structure can greatly increase the specific surface area of the material, thereby exposing abundant active sites. In addition, the metal state Ni ₃ S ₂ has excellent electrical conductivity, which is beneficial to the electrons in the electrocatalytic water splitting process. transfer, greatly improving the catalytic efficiency of electrolyzed water.

6) The V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst prepared by the present invention has excellent water electrolysis performance. The electrocatalyst has a hydrogen production overpotential of 146mV at a current density of 10mA cm ^-2 , a hydrogen production overpotential of 259mV at a current density of 100mA cm ^-2 , and a hydrogen production overpotential of 1000mA cm ^-2 at a current density of 1000mA cm-2. The hydrogen production overpotential is 503mV; under the current density of 100mA cm ^-2 , the oxygen production overpotential is 328mV, showing a relatively excellent electrochemical hydrogen production and oxygen production activity.

Description of drawings

1 is the XRD pattern of the V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst prepared in Example 4 of the present invention;

Fig. 2 is the SEM spectrum of the V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst prepared in Example 4 of the present invention;

3 is the LSV hydrogen production performance curve of the V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst prepared in Example 4 of the present invention;

FIG. 4 is the LSV oxygen generation performance curve of the V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst prepared in Example 4 of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings.

Example 1:

1) Weigh 100 mg of vanadium chloride (VCl ₃ ) and 80 mg of urea into 30 mL of deionized water simultaneously, and magnetically stir to obtain uniform solution A;

2) Transfer solution A to a 50 mL reaction kettle, add clean nickel foam and immerse it in solution A for hydrothermal reaction at 150° C. for 10 hours, wash and dry to obtain NiV-LDH nanosheet array precursor;

3) Then add the mixed solution B formed by 30mL of ethanol solvent and tert-dodecanethiol in the 50mL reaction kettle, control its volume ratio to be 5:1, and immerse it into the NiV-LDH nanosheet array precursor, and place it in a solvothermal solution at 180°C. After 4 h of reaction, cleaning and drying, a V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst was obtained.

Example 2:

1) Weigh 120 mg of vanadium chloride (VCl ₃ ) and 60 mg of urea into 20 mL of deionized water simultaneously, and magnetically stir to obtain a homogeneous solution A;

2) Transfer solution A to a 50 mL reaction kettle, add clean nickel foam and immerse it in solution A for hydrothermal reaction at 130 °C for 8 h, wash and dry to obtain NiV-LDH nanosheet array precursor;

3) Then add the mixed solution B formed by 20 mL of ethanol solvent and tert-dodecanethiol in the 50 mL reaction kettle, control its volume ratio to be 7:1, and immerse it in the NiV-LDH nanosheet array precursor, and place it in a solvothermal solution at 140 °C. The reaction was carried out for 6 h, washed and dried to obtain a V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst.

Example 3:

1) Weigh 90 mg of vanadium chloride (VCl ₃ ) and 75 mg of urea into 25 mL of deionized water simultaneously, and magnetically stir to obtain uniform solution A;

2) Transfer solution A to a 50 mL reaction kettle, add clean nickel foam and immerse it in solution A for hydrothermal reaction at 180° C. for 12 h, wash and dry to obtain NiV-LDH nanosheet array precursor;

3) Then add the mixed solution B formed by 25mL ethanol solvent and tert-dodecanethiol into the 50mL reaction kettle, control its volume ratio to be 9:1, and immerse it in the NiV-LDH nanosheet array precursor, and place it in a solvothermal solution at 120°C. The reaction was carried out for 3 h, washed and dried to obtain a V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst.

Example 4:

1) Weigh 110 mg of vanadium chloride (VCl ₃ ) and 70 mg of urea into 30 mL of deionized water simultaneously, and magnetically stir to obtain uniform solution A;

2) Transfer solution A to a 50 mL reaction kettle, add clean nickel foam and immerse it in solution A for hydrothermal reaction at 160 °C for 10 h, wash and dry to obtain NiV-LDH nanosheet array precursor;

3) Then add the mixed solution B formed by 30mL ethanol solvent and tert-dodecanethiol into the 50mL reaction kettle, control its volume ratio to be 5:1, and immerse the NiV-LDH nanosheet array precursor, and place it at 150°C solvothermal The reaction was carried out for 5 h, washed and dried to obtain a V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst.

It can be seen from Figure 1 that the characteristic peaks of Ni ₃ S ₂ are displayed at 21.7°, 31.1°, 37.7°, 50.1°, and 55.3°; the characteristic peaks of nickel foam are displayed at 44.5° and 51.8°. The phases of the flakes and nanorods are both Ni ₃ S ₂ .

It can be seen from Figure 2 that the sample exhibits the morphology of the V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure. The lush nanorod structure at the edge of the nanosheet can greatly increase the specific surface area of the material, thereby The abundant active sites are exposed, which is beneficial to the electrocatalytic hydrogen production and oxygen production.

It can be seen from Figure 3 that at a current density of 10mA cm ^-2 , the hydrogen production overpotential is 146mV, and at a current density of 100mA cm ^-2 , the hydrogen production overpotential is 259mV, and at a current density of 1000mA cm ^-2 , the hydrogen production overpotential is 259mV. The hydrogen production overpotential is 503 mV, showing a relatively excellent hydrogen production activity.

It can be seen from Figure 4 that under the current density of 100mA cm ^-2 , the oxygen production overpotential is 328mV, and the electrochemical oxygen production performance is excellent.

Example 5:

1) Weigh 120 mg of vanadium chloride (VCl ₃ ) and 65 mg of urea into 20 mL of deionized water simultaneously, and magnetically stir to obtain a homogeneous solution A;

2) Transfer solution A to a 50 mL reaction kettle, add clean nickel foam and immerse it in solution A for hydrothermal reaction at 170 °C for 12 h, wash and dry to obtain NiV-LDH nanosheet array precursor;

3) Then add the mixed solution B formed by 20 mL of ethanol solvent and tert-dodecanethiol in the 50 mL reaction kettle, control its volume ratio to be 7:1, and immerse it in the NiV-LDH nanosheet array precursor, and place it in a solvothermal solution at 200 °C. The reaction was carried out for 3 h, washed and dried to obtain a V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst.

Example 6:

1) Weigh 80 mg of vanadium chloride (VCl ₃ ) and 70 mg of urea into 25 mL of deionized water simultaneously, and magnetically stir to obtain uniform solution A;

2) Transfer solution A to a 50 mL reaction kettle, add clean nickel foam and immerse it in solution A for hydrothermal reaction at 150° C. for 8 hours, wash and dry to obtain NiV-LDH nanosheet array precursor;

3) Then add the mixed solution B formed by 25mL ethanol solvent and tert-dodecanethiol into the 50mL reactor, control its volume ratio to be 10:1, and immerse the NiV-LDH nanosheet array precursor, and place it in a solvothermal solution at 140°C. After reaction for 5 h, a V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst was obtained after cleaning and drying.

Claims (5)

1. a preparation method of V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst, is characterized in that: 1) Weigh 80-120 mg of vanadium chloride (VCl ₃ ) and 60-80 mg of urea into 20-30 mL of deionized water at the same time, and magnetically stir to obtain a uniform solution A; 2) Transfer solution A to a 50 mL reaction kettle, add clean nickel foam and immerse it in solution A for hydrothermal reaction at 130-180° C. for 8-12 hours, wash and dry to obtain NiV-LDH nanosheet array precursor; 3) Then add 20-30 mL of mixed solution B formed by ethanol solvent and tert-dodecanethiol solvent into the 50 mL reaction kettle, and immerse it in the NiV-LDH nanosheet array precursor, and place it at 120-200 ℃ for solvothermal reaction for 3-6 h , washed and dried to obtain V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst. 2 . The preparation method of the V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst according to claim 1 , wherein the area of the nickel foam in the step 2) is 1 cm*5 cm. 3 . 3. The preparation method of V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst according to claim 1, characterized in that: the mixed solution B of the step 3) is ethanol and tert-dodecanethiol The volume ratio is 5:1 to 10:1. 4. A V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst prepared by the preparation method as claimed in claim 1, characterized in that: a nanosheet/nanorod composite structure is synthesized on the surface of the nickel foam. V- _{doped Ni3S2} material. 5. The V-doped Ni ₃ S ₂ nanosheet/nanorod composite structure electrocatalyst according to claim 4, wherein the electrocatalyst has a hydrogen production overpotential of 146mV at a current density of 10mA cm ^-2 , under the current density of 100mA cm ^-2 , its hydrogen production overpotential is 259mV, under the current density of 1000mA cm ^-2 , its hydrogen production overpotential is 503mV; under the current density of 100mA cm ^-2 , its oxygen production The overpotential is 328mV, which shows excellent electrochemical hydrogen production and oxygen production activity.

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