Alkaline seawater hydrogen evolution catalyst and preparation and application thereof

Abstract

The application relates to the technical field of preparation of hydrogen production catalysts for electrolysis of water, in particular to a basic seawater hydrogen evolution catalyst and preparation and application thereof, and a basic seawater hydrogen evolution catalyst CN@NiMoN is prepared, through a simple hydrothermal and calcination process, the prepared uniformly nitrogen-doped carbon-coated high-activity nitride has high catalytic activity and long-time stability, and the application provides a prospect for large-scale hydrogen production by electrolysis of seawater.

Description

TECHNICAL FIELD

[0001] The application relates to the preparation of a hydrogen catalyst for electrolysis of water, in particular to a high-catalytic-activity CN@NiMoN catalyst and application of a preparation method thereof to alkaline electrolysis of seawater. BACKGROUND

[0002] In order to alleviate the increasingly serious environmental pollution and the consumption of fossil fuels, fossil energy is gradually shifted to sustainable non-fossil energy, which is the demand of the development of the times. Hydrogen is hailed as the most promising clean energy in the 21st century due to its high energy density, cleanliness, and sustainability. Among them, electrolysis of water can achieve zero carbon emissions in the hydrogen production process, and is one of the most important green hydrogen production methods. Due to the scarcity of fresh water resources, electrolysis of seawater for hydrogen production has attracted widespread attention from researchers as a large-scale hydrogen production strategy.

[0003] However, due to the presence of a large number of inorganic ions (Na + , Cl - , Mg 2+ , Ca 2+ , etc.) and organic pollutants in seawater, the electrode reaction is significantly affected, such as slow reaction kinetics and poor electrode stability. The common electrocatalysts for hydrogen evolution reaction include platinum (Pt) based materials and transition metal compounds. Due to the high cost of platinum-based catalysts, transition metals and their derivatives are widely used in the field of electrocatalysis due to their advantages of low cost, high efficiency, and stability. However, their slow reaction, poor conductivity, and limited hydrogen adsorption sites limit their further development, especially in complex seawater systems, and their stability also fails to meet the needs of industrialization. SUMMARY

[0004] In view of the shortcomings and deficiencies of the prior art, the present application prepares a uniform nitrogen-doped carbon-coated high-activity nitride with high catalytic activity and long-term stability through a simple hydrothermal and calcination process, providing a prospect for large-scale hydrogen production by electrolysis of seawater.

[0005] Specifically, the application is implemented through the following technical scheme, which comprises the following steps:

[0006] A. Treatment of the foam nickel substrate: Take a certain area of foam nickel and sequentially ultrasonic in hydrochloric acid, acetone and deionized water for 10 minutes each to remove the surface oxides and organic matter, and place in a vacuum drying box until completely dry.

[0007] B. Preparation of the reaction precursor: weigh a certain amount of nickel salt, molybdenum salt and a certain amount of solvent, stir uniformly, and transfer to the inner liner of the reaction kettle, place the treated A into the solution in the vacuum drying box and keep constant temperature for a period of time, after the reaction is completed, naturally cool to room temperature, and then wash and dry.

[0008] C, loading of carbon precursor: a certain amount of carbon source is placed in a certain amount of solvent, and a base solution is added to adjust the pH to a suitable value. The dried precursor B is placed in the solvent, soaked and stirred for several hours, and then washed and dried.

[0009] D, preparation of carbon-coated nitride: the C precursor is placed in a tube furnace, heated to a certain temperature under ammonia atmosphere, and kept for several hours. Naturally cool to room temperature.

[0010] Compared with the prior art, the present application has the following advantages:

[0011] The present application prepares a core-shell structure of carbon-coated transition metal nitride catalyst, which is composed of a 1.5nm thick carbon layer coated with a 32nm nitride nanosphere. Through the strong electrostatic attraction between the carbon layer and the nanocatalyst, the structure collapse during high-temperature nitriding is avoided, and the influence of Ca 2+ and Mg 2+ on the long-term stability of the counter electrode is avoided, which significantly improves the activity and long-term stability of the catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is the XRD pattern of the electrode prepared in Example 2 and the standard card. where each curve corresponds to CN NiMoN, Mo 0.8 Ni 0.2 N, Ni3N XRD curve.

[0013] Figure 2 is the linear sweep voltammogram of the electrode prepared in Example 6 in alkaline 1M KOH electrolyte. Each curve corresponds to the potential-current density curve of NiMoO, NiMoN, CN@NiN, CN@MoN, CN@NiMoN, respectively.

[0014] Figure 3 is the overpotential-time curve of the electrode prepared in Example 3 in 1M KOH electrolyte. DETAILED DESCRIPTION

[0015] The present application will be described in detail below in conjunction with the examples, but the present application is not limited to these examples.

[0016] Unless otherwise specified, the raw materials in the examples of the present application are purchased through commercial channels.

[0017] Example 1

[0018] A, treatment of foam nickel substrate: take foam nickel with thickness x length x width = 2mm x 4cm x 4cm, and sequentially ultrasonic 1M hydrochloric acid, acetone, deionized water for 10min respectively, remove the surface oxides and organic matter, and place in a vacuum drying oven at 60℃ for 10h.

[0019] B, Preparation of reaction precursor: 0.8812 g of nickel nitrate, 0.3623 g of ammonium molybdate and 60 ml of anhydrous ethanol solvent were weighed and stirred uniformly, and were transferred into the inner liner of the reaction kettle. The foam nickel substrate treated in step A was placed to be immersed in the solution, and was kept in a vacuum drying box at 120°C for 10 h. After the reaction was completed, the foam nickel was taken out after natural cooling to room temperature, and was washed and dried to obtain a nickel molybdenum oxide precursor.

[0020] C, Loading of carbon precursor: 0.5 g of glucose was weighed and placed in 50 ml of anhydrous ethanol solvent, and 1M NaOH lye was added to adjust the pH to 8. The precursor dried in step B was placed in the solution, and was soaked and stirred for 3 h. The foam nickel was taken out, washed and dried to obtain a polymer-coated nickel molybdenum oxide precursor.

[0021] D, Preparation of carbon-coated nitride: the precursor obtained in step C was placed in a tube furnace, and was heated from room temperature to 300°C at a rate of 5°C / min under an ammonia atmosphere of 100 ml / min, and was kept for 3 h. The natural cooling to room temperature obtained a carbon-coated 20-50 nm nickel molybdenum nitride catalyst product (CN@NiMoN) with a thickness of 1-5 nm. The material composition was as follows: Figure 1 .

[0022] E, Application of catalyst product: the carbon-coated nitride catalyst (CN@NiMoN) prepared in step D was cut into 1x1 mm as a negative electrode, and the foam nickel was used as an anode. A saturated calomel electrode was used as a reference electrode, and the electrolyte was 1M KOH and 1M KOH+seawater (1M KOH seawater), respectively. The polarization curve was obtained by scanning from -0.5V to 0V (vs RHE) at a scanning speed of 2mV / s. Figure 2 . The stability was tested after 100 h at a current density of -0.1Acm -2 . Figure 3 The carbon-coated metal nitride hydrogen evolution catalyst prepared in the application has a 10mA cm -2 -1 hydrogen evolution overpotential of 44.3 and 100.3 mV, respectively.

[0023] Example 2

[0024] A, Treatment of foam nickel substrate: a foam nickel with thickness x length x width = 2 mm x 4 cm x 4 cm was sequentially ultrasonically cleaned with 1M hydrochloric acid, acetone and deionized water for 10 min each to remove surface oxides and organic matter, and was dried in a vacuum drying box at 60°C for 10 h.

[0025] B. Preparation of reaction precursor: Weigh 0.8812g of nickel sulfate, 0.3623g of sodium molybdate and 60ml of anhydrous ethanol solvent, stir evenly and transfer to the liner of the reaction vessel. Place the foamed nickel substrate treated in step A into the solution and keep it at 150℃ for 10h in a vacuum drying oven. After the reaction is completed, let it cool naturally to room temperature, take out the foamed nickel, wash and dry it to obtain the nickel molybdenum oxide precursor.

[0026] C. Loading of carbon precursor: Weigh 0.2g of glucose and place it in 50ml of anhydrous ethanol solvent, and add 0.1M NaOH alkali solution to adjust the pH to 8. Place the precursor dried in step B into the solution, soak and stir for 3h, then take out the foam nickel, wash and dry to obtain polymer-coated nickel-molybdenum oxide precursor.

[0027] D. Preparation of carbon-coated nitrides: The precursor obtained in step C was placed in a tube furnace and heated from room temperature to 400°C at a rate of 5°C / min under an ammonia atmosphere of 100 ml / min and held for 2 h. It was then naturally cooled to room temperature to obtain a 20-50 nm thick nickel-molybdenum nitride catalyst product (CN@NiMoN) with carbon coating.

[0028] E. Application of the catalyst product: The process and conditions are the same as step E in Example 1, and the results are the same. Figure 1 and Figure 2 The characterization data of CN@NiMoN in Example 1 are similar. The hydrogen evolution overpotentials of the carbon-coated metal nitride prepared in this invention at 10 mA cm⁻² in 1M KOH and 1M KOH + seawater electrolytes are 55.6 and 120 mV, respectively.

[0029] Example 3

[0030] A. Treatment of nickel foam substrate: Take a piece of nickel foam with a thickness × length × width of 2mm × 4cm × 4cm and sonicate it for 10min each with 1M hydrochloric acid, acetone and deionized water to remove surface oxides and organic matter. Then place it in a vacuum drying oven at 60℃ for 10h.

[0031] B. Preparation of reaction precursor: Weigh 0.8812g nickel nitrate, 0.1232g sodium molybdate and 60ml anhydrous ethanol solvent, stir evenly and transfer to the liner of the reaction vessel. Place the foamed nickel substrate treated in step A into the solution and keep it at 120℃ for 6 hours in a vacuum drying oven. After the reaction is completed, let it cool naturally to room temperature, take out the foamed nickel, wash and dry it to obtain the nickel molybdenum oxide precursor.

[0032] C. Carbon precursor loading: 0.2 g of dopamine hydrochloride was placed in 50 ml of anhydrous ethanol solvent, and 1 M NaOH lye was added to adjust the pH to 10. The precursor dried in step B was placed in the solution, and after 0.5 h of immersion and stirring, the foamed nickel was removed, washed, and dried to obtain a polymer-coated nickel molybdenum oxide precursor.

[0033] D. Preparation of carbon-coated nitride: The precursor obtained in step C was placed in a tube furnace, and under an ammonia atmosphere of 100 ml / min, it was heated from room temperature to 500°C at a rate of 5°C / min and maintained for 4 h, and then naturally cooled to room temperature to obtain a carbon-coated nickel molybdenum nitride catalyst product (CN@NiMoN) with a thickness of 1-5 nm and a size of 20-50 nm.

[0034] E. Application of the catalyst product: The process and conditions were the same as in example 1, step E, and the results were similar to the characterization data of CN@NiMoN in example 1 of Figure 1 and Figure 2 The carbon-coated metal nitride hydrogen evolution catalyst prepared in the application has a hydrogen evolution overpotential of 38 mV and 89 mV at 10 mA cm-2 in 1 M KOH and 1 M KOH + seawater electrolyte, respectively.

[0035] Example 4

[0036] A. Treatment of foamed nickel substrate: A foamed nickel with thickness x length x width = 2 mm x 4 cm x 4 cm was sequentially ultrasonically cleaned with 1 M hydrochloric acid, acetone, and deionized water for 10 min each to remove surface oxides and organic matter, and then placed in a vacuum drying oven at 60°C for 10 h.

[0037] B. Preparation of reaction precursor: 0.4312 g of nickel chloride, 0.3623 g of zinc molybdate, and 60 ml of anhydrous ethanol solvent were stirred uniformly and transferred to the inner liner of a reaction kettle. The foamed nickel substrate treated in step A was placed in the solution, and then kept at 180°C in a vacuum drying oven for 10 h. After the reaction was completed, the foamed nickel was removed, washed, and dried to obtain a nickel molybdenum oxide precursor.

[0038] C. Carbon precursor loading: 0.2 g of dopamine hydrochloride was placed in 50 ml of anhydrous ethanol solvent, and 1 M NaOH lye was added to adjust the pH to 10. The precursor dried in step B was placed in the solution, and after 0.5 h of immersion and stirring, the foamed nickel was removed, washed, and dried to obtain a polymer-coated nickel molybdenum oxide precursor.

[0039] D. Preparation of carbon-coated nitride: The precursor obtained in step C was placed in a tube furnace, and heated from room temperature to 600 °C at a rate of 5 °C / min under an ammonia atmosphere of 100 ml / min, and kept for 1 h. The temperature was then allowed to cool naturally to room temperature. A carbon-coated nickel-molybdenum nitride catalyst product (CN@NiMoN) with a thickness of 1-5 nm and a particle size of 20-50 nm was obtained.

[0040] E. Application of the catalyst product: The process and conditions were the same as in Example 1, step E. The results were similar to the characterization data of CN@NiMoN in Example 1 of Figure 1 and Figure 2 The carbon-coated metal nitride hydrogen evolution catalyst prepared in the present application had a hydrogen evolution overpotential of 44.8 mV and 96 mV in 1M KOH and 1M KOH + seawater electrolyte, respectively, at a current density of 10 mA cm-2.

[0041] Example 5

[0042] A. Treatment of the nickel foam substrate: A nickel foam with dimensions of 2 mm x 4 cm x 4 cm was sequentially treated with 1M hydrochloric acid, acetone, and deionized water for 10 min each under ultrasonication to remove surface oxides and organic matter. The nickel foam was then dried in a vacuum drying oven at 60 °C for 10 h.

[0043] B. Preparation of the reaction precursor: 1.2623 g of nickel nitrate and 0.3623 g of sodium molybdate were weighed into a 60 ml anhydrous ethanol solvent and stirred until uniform. The treated nickel foam substrate from step A was then placed in the solution and transferred to the inner liner of a reaction kettle. The kettle was kept in a vacuum drying oven at 150 °C for 6 h. After the reaction was complete, the nickel foam was removed and washed and dried to obtain a nickel-molybdenum oxide precursor.

[0044] C. Loading of the carbon precursor: 0.2 g of glucose was weighed into a 60 ml anhydrous ethanol solvent and 1M NaOH was added to adjust the pH to 8. The dried precursor from step B was then placed in the solution and stirred for 2 h. The nickel foam was then removed, washed, and dried to obtain a polymer-coated nickel-molybdenum oxide precursor.

[0045] D. Preparation of carbon-coated nitride: The precursor obtained in step C was placed in a tube furnace, and heated from room temperature to 600 °C at a rate of 5 °C / min under an ammonia atmosphere of 100 ml / min, and kept for 1 h. The temperature was then allowed to cool naturally to room temperature. A carbon-coated nickel-molybdenum nitride catalyst product (CN@NiMoN) with a thickness of 1-5 nm and a particle size of 20-50 nm was obtained.

[0046] E. Application of the catalyst product: The process and conditions were the same as in Example 1, step E. The results were similar to the characterization data of CN@NiMoN in Example 1 of Figure 1 and Figure 2The characterization data of CN@NiMoN in Example 1 are similar. The carbon-coated metal nitride hydrogen evolution catalyst prepared by the present application has a hydrogen evolution overpotential of 78.5 mV and 150 mV in 1M KOH and 1M KOH+seawater electrolyte at 10 mA cm-2, respectively.

[0047] Example 6

[0048] A, treatment of the foam nickel substrate: take the foam nickel with thickness x length x width = 2 mm x 4 cm x 4 cm, and sequentially ultrasonic in 1M hydrochloric acid, acetone, and deionized water for 10 min each, to remove the surface oxides and organic matter, and place in a vacuum drying oven at 60°C for 10 h.

[0049] B, preparation of the reaction precursor: weigh 0.4412 g of nickel sulfate, 0.3623 g of sodium molybdate, and 60 ml of anhydrous ethanol solvent, and stir uniformly, and transfer to the inner liner of the reaction kettle, and place the foam nickel substrate treated in step A immersed in the solution, and keep in a vacuum drying oven at 180°C for 6 h, after the reaction is completed, naturally cool to room temperature, and take out the foam nickel to wash and dry, to obtain the nickel molybdenum oxide precursor.

[0050] C, loading of the carbon precursor: weigh 0.3 g of dopamine hydrochloride, and place in 100 ml of deionized water solvent, and add 1M NaOH lye to adjust the pH to 12, and place the precursor dried in step B in the solution, and soak and stir for 1 h, and take out the foam nickel to wash and dry, to obtain the carbon-coated 20-50 nm nickel molybdenum nitride catalyst product (CN@NiMoN) with a thickness of 1-5 nm.

[0051] D, preparation of the carbon-coated nitride: place the precursor obtained in step C in a tube furnace, and heat from room temperature to 500°C at a rate of 5°C / min under an ammonia gas atmosphere of 60 ml / min, and keep for 1 h, and naturally cool to room temperature, to obtain the carbon-coated nickel molybdenum nitride catalyst product.

[0052] E, application of the catalyst product: the process and conditions are the same as in step E of Example 1, and the results are similar to Figure 1 and Figure 2 The characterization data of CN@NiMoN in Example 1 are similar. The carbon-coated metal nitride hydrogen evolution catalyst prepared by the present application has a hydrogen evolution overpotential of 78.5 mV and 150 mV in 1M KOH and 1M KOH+seawater electrolyte at 10 mA cm-2, respectively.

Claims

1. A method for preparing an alkaline seawater hydrogen evolution catalyst, characterized in that: 1) preparation of a reaction precursor: 0.2-1.5 g of a nickel salt, 0.1-0.6 g of a molybdenum salt and 20-100 ml of a solvent are stirred uniformly to form a solution; a foamed nickel substrate is immersed in the solution at a constant temperature of 100-180°C for 4-12 h, after the reaction is completed, the precursor is obtained by washing and drying after cooling to room temperature; the size of the foamed nickel substrate is 1-3 mm thick x 2-5 cm long x 2-5 cm wide; 2) loading of a carbon precursor: 0.2-1 g of a carbon source is placed in 20-100 ml of a solvent, and an alkali solution is added to adjust the pH value to 6-12; the precursor is placed in the solvent, soaked and stirred for 0.5-5 h, and then washed and dried to obtain the precursor; the carbon source is one or more than two of glucose, sucrose, hydroxylamine hydrochloride and urea; 3) preparation of a carbon-coated nitride: the precursor is placed in a tube furnace, heated to a temperature of 300-600°C under an ammonia atmosphere, and kept for 1-3 h to obtain a carbon-coated 20-50 nm nickel molybdenum nitride catalyst product CN@NiMoN with a thickness of 1-5 nm.

2. The method according to claim 1, characterized in that: in step 1), the foamed nickel substrate is immersed in the solution at a constant temperature of 120-150°C for 6-10 h, after the reaction is completed, the precursor is obtained by washing and drying after cooling to room temperature; in step 2), loading of a carbon precursor: 0.2-1 g of a carbon source is placed in 20-100 ml of a solvent, and an alkali solution is added to adjust the pH value to 9-10; the precursor is placed in the solvent, soaked and stirred for 2-2.5 h, and then washed and dried to obtain the precursor; in step 3), preparation of a carbon-coated nitride: the precursor is placed in a tube furnace, heated to a temperature of 450-500°C under an ammonia atmosphere, and kept for 2-2.5 h to obtain the catalyst product.

3. The method according to claim 1, characterized in that: the foamed nickel substrate needs to be cleaned before use, and the specific process is as follows: the foamed nickel with a size of 1-3 mm thick x 2-5 cm long x 2-5 cm wide is sequentially subjected to ultrasonic treatment in 0.1-3 M hydrochloric acid, acetone and deionized water for 1-30 min, and then dried.

4. The method according to claim 1 or 2, characterized in that: the foamed nickel is sequentially subjected to ultrasonic treatment in 0.1-1 M hydrochloric acid, acetone and deionized water for 1-30 min, and then dried. The solvent is one or more than two of anhydrous ethanol, water and acetone.

6. The method according to claim 1, characterized in that: the nickel salt is one or more than two of nickel nitrate, nickel sulfate, nickel chloride and nickel hydroxide; the molybdenum salt is one or more than two of sodium molybdate, ammonium molybdate, magnesium molybdate and zinc molybdate.

7. The method according to claim 5 or 6, characterized in that: the solvent is deionized water, the nickel salt is nickel nitrate, and the molybdenum salt is ammonium molybdate.

8. The method according to claim 1, characterized in that: the carbon source is glucose. ​ ​ ​ ​ ​ 5. The method of claim 1, wherein: ​ ​ ​ ​ ​ ​ ​ ​ The alkali solution is one or two or more of 0.1-3 M NaOH, 0.1-3 M KOH, and ammonia water. The ammonia gas flow rate is 20-100 ml / min.

9. A catalyst prepared by the method of any one of claims 1-8.

10. Use of the catalyst of claim 9 in an alkaline seawater battery or water electrolyzer.

11. Use according to claim 10, characterized in that: The catalyst is used as a hydrogen evolution catalyst for alkaline seawater.

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