Preparation method and application of surface hydroxylation platinum-nickel bimetallic seawater hydrogen production catalyst

Abstract

The invention relates to the technical field of catalysts, in particular to a preparation method and application of a surface-hydroxylated platinum-nickel bimetallic catalyst for seawater hydrogen production, and the preparation method comprises the following steps: firstly, weighing ketjen black, and acidizing in a mixed acid environment to optimize surface properties; carrying out hydroxyl functional modification on the surface; and finally, uniformly dispersing the modified sample in an ethylene glycol solvent, and enabling platinum and nickel metals to grow in a carbon matrix in a binary alloy form through a high-temperature reduction method, so as to obtain the surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst. Electrochemical tests show that the prepared catalyst shows excellent catalytic performance in the field of seawater hydrogen production, the current density in seawater can reach 4200 mAcm <-2 >, and the performance of the catalyst is nearly 3 times (1500 mA cm <-2 >) of commercial PtC under the same overpotential. Meanwhile, the prepared catalyst also has excellent hydrogen evolution reaction stability, is low in cost, economical and environment-friendly, and has a wide application prospect in the field of seawater electrolysis hydrogen production.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a preparation method and application of a surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst. Background Art

[0003] Hydrogen energy can be divided into green hydrogen, gray hydrogen, blue hydrogen, etc. according to different production methods. Among them, green hydrogen has become the best choice for green hydrogen production because it uses renewable energy to generate electricity. Seawater hydrogen production is an important way to produce green hydrogen, and it has broad development prospects because its raw materials are almost not restricted by geographical regions and have abundant reserves. Seawater hydrogen production is to decompose the water in seawater into hydrogen and oxygen by electrolysis. However, since seawater contains a large amount of salts and impurities, it places strict requirements on electrolysis equipment and catalysts; at the same time, in the water electrolysis system, the choice of catalyst also greatly affects the efficiency of the cathode hydrogen evolution reaction and the anode oxygen evolution reaction. Therefore, the development of an efficient catalyst system with high current density, salt corrosion resistance, high activity, high stability and easy scalability in seawater is the key to promoting the development of seawater hydrogen production.

[0004] Commonly used catalysts on the market can be roughly divided into precious metals and non-precious metals. Pt and Ru in the precious metal category are common precious metal catalysts, which have unfilled d orbitals, which facilitate the adsorption of reactants and have a higher reaction rate. In addition, precious metal catalysts have excellent selectivity and stability in a variety of environments such as high temperature and high pressure, and are the only choice as seawater hydrogen evolution catalysts. But at the same time, its high price hinders a large number of industrial applications. Therefore, the development of a seawater hydrogen production catalyst that can reduce the Pt content, improve atomic utilization, reduce production costs, and improve hydrogen evolution performance is an important link in realizing the industrial production of green hydrogen. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and propose a preparation method and application of a surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst. The prepared catalyst has excellent hydrogen evolution reaction stability, low cost, economy and environmental protection, and has broad application prospects in the field of electrolysis of seawater for hydrogen production.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst, the specific steps are as follows:

[0008] Step 1, synthesis of acid-treated Ketjen black: weigh a certain amount of Ketjen black and evenly disperse it in an acidic solution prepared by hydrochloric acid, nitric acid and deionized water, then react for 15 to 24 hours under the combined action of oil bath heating and magnetic stirring, then filter and centrifuge and wash several times until the washing solution is neutral, and vacuum dry to obtain the acid-treated Ketjen black;

[0009] Step 2, hydroxyl functionalization of Ketjen black surface: The acid-treated Ketjen black was uniformly dispersed in a Tris-HCl buffer solution at pH 8.5, and then dopamine hydrochloride was added to the system and magnetically stirred for 3 hours. After multiple washings, it was dispersed again in a Tris-HCl buffer solution at pH 7.0, and dextran (T-40) was added as a hydroxylation agent. The reaction was carried out in an oil bath for 17 hours, and the samples were centrifuged, washed, vacuum dried, and collected.

[0010] Step 3, preparation of surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst: the sample prepared in the above step 2 is evenly dispersed in ethylene glycol, and then platinum and nickel metal salt precursor solutions are added to the system, and ultrasound is continued; then ascorbic acid is added as a reducing agent, and the reaction is carried out in a high-temperature oil bath for 12 hours under the action of magnetic stirring. After the reaction is completed, the surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst is obtained by centrifugal washing and vacuum drying.

[0011] Preferably, in step 1, the amount of Ketjen black is 0.5 g, the amount of hydrochloric acid is 35 mL, the amount of nitric acid is 35 mL, and the amount of deionized water is 70 mL.

[0012] Preferably, in step 1, the oil bath temperature is 90-100° C., and the cleaning condition is rinsing with deionized water, which is repeated 4-5 times.

[0013] Preferably, in step 2, the amount of acid-treated Ketjen black is 50 mg, the amount of Tris-HCl buffer with a pH of 8.5 is 10 mL, the amount of dopamine hydrochloride is 5 mg, the amount of dextran is 50-350 mg, and the amount of Tris-HCl buffer with a pH of 7.0 is 10 mL.

[0014] Preferably, in step 2, the oil bath temperature is 30-40°C, and the magnetic stirring speed is 400-410 rmin. -1 , the vacuum drying time is 20 to 24 hours.

[0015] Preferably, in step 3, the amount of sample is 8 mg, the amount of ethylene glycol is 10-12 mL, the platinum metal salt precursor is potassium tetrachloroplatinate, the amount of which is 14 mg, the nickel metal salt precursor is nickel nitrate, the amount of which is 42 mg, and the amount of ascorbic acid is 120 mg.

[0016] Preferably, in step 3, the ultrasonic temperature is 0-20°C, the oil bath temperature is 90-100°C, and the magnetic stirring speed is 400-410 r min -1 .

[0017] The present invention also provides an application of the surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst obtained by the above preparation method in hydrogen evolution reaction (HER).

[0018] By adopting the above technical solution, the significant advantages of the catalyst include: First, the catalyst uses platinum-nickel binary alloy as the active component, which can not only reduce the platinum loading and reduce the cost of hydrogen production, but also improve the electrocatalytic activity and achieve a high current density output at a low overpotential. Its current density in seawater can reach 4200mAcm -2 , at the same overpotential (609mV), the performance is nearly 3 times that of commercial PtC (1500mAcm -2 ); secondly, through surface functionalization treatment, hydroxyl modification not only improves the catalyst performance, but also further improves the stability of the catalyst.

[0019] In seawater, the hydrogen evolution reaction (HER) test results show that PtNiNC-OH 0.25 The current density can reach 4200mAcm -2 , the performance is nearly three times that of commercial PtC (1500mA cm -2 ), which shows that the surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst prepared by the present invention has good application and commercial prospects. -2 At a current density of 0.25 The overpotential of the commercial PtC is 31.88mV, and the overpotential of the commercial PtC is 79.31mV. Under the same current density, the smaller the overpotential, the better. This further proves that the catalytic activity of the hydroxylated PtN bimetallic seawater hydrogen production catalyst in the hydrogen evolution reaction is better than that of the commercial PtC. Therefore, this surface hydroxylated PtN bimetallic seawater hydrogen production catalyst will have great potential in the field of seawater electrolysis.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst prepared by the present invention has excellent activity and stability, and can achieve a large current density at an extremely low overpotential (the current density of PtNiNC-OH0.25 can reach 4200mAcm -2 , at the same overpotential (609mV), the performance is nearly 3 times that of commercial PtC (1500mAcm -2 ), has great potential in the field of seawater electrolysis and has broad application prospects.

[0022] 2. The surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst prepared by the present invention can maintain good catalytic activity, and the reaction conditions of its preparation method are also relatively mild. Compared with commercial PtC on the market, it is low-cost, economical and environmentally friendly, and has better catalytic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 PtNiNC-OH prepared in Examples 1, 2, 3 and Comparative Example 1 of the present invention 0.15 、PtNiNC-OH 0.25 、PtNiNC-OH 0.35 , infrared spectrum image of PtNiNC sample;

[0024] Figure 2 PtNiNC-OH prepared in Examples 1, 2, 3 and Comparative Example 1 of the present invention 0.15 、PtNiNC-OH 0.25 、PtNiNC-OH 0.35 , XRD patterns of PtNiNC samples;

[0025] Figure 3 PtNiNC-OH prepared in Example 2 of the present invention and Comparative Example 1 0.25 , TEM image of PtNiNC sample and its corresponding EDS element spectrum distribution diagram;

[0026] Figure 4 PtNiNC-OH prepared in Examples 1, 2, and 3 of the present invention and Comparative Examples 1 and 2 0.15 、PtNiNC-OH 0.25 、PtNiNC-OH 0.35 Comparison of HER performance of PtNiNC and commercial PtC in seawater. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the protection scope of the present invention. The embodiments described in the present invention are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0028] Example 1

[0029] Surface hydroxylated platinum-nickel bimetallic catalyst for hydrogen production from seawater PtNiNC-OH 0.15 Preparation method:

[0030] (1) Synthesis of acid-treated Ketjen black:

[0031] a) Add 35 mL of hydrochloric acid, nitric acid and 70 mL of deionized water into a flask containing 0.5 g of Ketjen Black, and heat in an oil bath for 15 to 24 h at 100 °C with magnetic stirring under condensation reflux conditions.

[0032] b) After the reaction is completed, water is added and allowed to stand overnight, then filtered and centrifuged 4 to 5 times until the washing liquid is neutral, and vacuum dried to obtain acid-treated Ketjen black.

[0033] (2) Hydroxyl functionalization of Ketjen black surface:

[0034] a) Weigh 50 mg of acid-treated Ketjen Black and evenly disperse it in 10 mL of Tris-HCl (pH 8.5).

[0035] b) Then, 5 mg of dopamine hydrochloride was added, and after magnetic stirring for 3 h, the mixture was washed with deionized water, anhydrous ethanol, and Tris-HCl (pH 7.0), respectively.

[0036] c) 0.15 g of dextran (T-40) was weighed and dissolved in 3 mL of deionized water to obtain a dextran solution.

[0037] d) The washed Ketjen black was redispersed in 10 mL of Tris-HCl (pH 7.0), and the dextran solution was added and reacted in an oil bath at 35° C. for 17 h.

[0038] e) After the reaction is completed, wash the mixture by centrifugation with deionized water and anhydrous ethanol for three times each, vacuum dry for 24 hours, and collect the samples.

[0039] (3) Preparation of surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst:

[0040] a) Weigh 8 mg of the sample prepared in (2) above, disperse it in 12 mL of ethylene glycol, and sonicate at low temperature for 30

[0041] min or above.

[0042] b) Add 14 mg of potassium tetrachloroplatinate and 42 mg of nickel nitrate, and continue low-temperature ultrasonication for more than 30 min.

[0043] c) Add 120 mg of ascorbic acid and stir under magnetic stirring at 100°C for 12 hours. After the reaction is completed, wash with deionized water for 2 to 3 times by centrifugation and dry in vacuum for 24 hours to obtain the surface hydroxylated platinum nickel bimetallic seawater hydrogen production catalyst PtNiNC-OH 0.15 .

[0044] Example 2

[0045] Surface hydroxylated platinum-nickel bimetallic catalyst for hydrogen production from seawater PtNiNC-OH 0.25 Preparation method:

[0046] (1) Synthesis of acid-treated Ketjen black:

[0047] a) Add 35 mL of hydrochloric acid, nitric acid and 70 mL of deionized water into a flask containing 0.5 g of Ketjen Black, and heat in an oil bath for 15 to 24 h at 100 °C with magnetic stirring under condensation reflux.

[0048] b) After the reaction is completed, water is added and allowed to stand overnight, then filtered and centrifuged 4 to 5 times until the washing liquid is neutral, and vacuum dried to obtain acid-treated Ketjen black.

[0049] (2) Hydroxyl functionalization of Ketjen black surface:

[0050] a) Weigh 50 mg of acid-treated Ketjen Black and evenly disperse it in 10 mL of Tris-HCl (pH 8.5).

[0051] b) Then, 5 mg of dopamine hydrochloride was added, and after magnetic stirring for 3 h, the mixture was washed with deionized water, anhydrous ethanol, and Tris-HCl (pH 7.0), respectively.

[0052] c) 0.25 g of dextran (T-40) was weighed and dissolved in 5 mL of deionized water to obtain a dextran solution.

[0053] d) The washed Ketjen black was redispersed in 10 mL of Tris-HCl (pH 7.0), and the dextran solution was added and reacted in an oil bath at 35° C. for 17 h.

[0054] e) After the reaction is completed, wash the mixture by centrifugation with deionized water and anhydrous ethanol for three times each, vacuum dry for 24 hours, and collect the samples.

[0055] (3) Preparation of surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst:

[0056] a) Weigh 8 mg of the sample prepared in (2) above, disperse it in 12 mL of ethylene glycol, and sonicate at low temperature for 30

[0057] min or above.

[0058] b) Add 14 mg of potassium tetrachloroplatinate and 42 mg of nickel nitrate, and continue low-temperature ultrasonication for more than 30 min.

[0059] c) Add 120 mg of ascorbic acid and stir under magnetic stirring at 100°C for 12 hours. After the reaction is completed, wash with deionized water for 2 to 3 times by centrifugation and dry in vacuum for 24 hours to obtain the surface hydroxylated platinum nickel bimetallic seawater hydrogen production catalyst PtNiNC-OH 0.25.

[0060] Example 3

[0061] Surface hydroxylated platinum-nickel bimetallic catalyst for hydrogen production from seawater PtNiNC-OH 0.35 Preparation method:

[0062] (1) Synthesis of acid-treated Ketjen black:

[0063] a) Add 35 mL of hydrochloric acid, nitric acid and 70 mL of deionized water into a flask containing 0.5 g of Ketjen Black, and heat in an oil bath for 15 to 24 h at 100 °C with magnetic stirring under condensation reflux conditions.

[0064] b) After the reaction is completed, water is added and allowed to stand overnight, then filtered and centrifuged 4 to 5 times until the washing liquid is neutral, and vacuum dried to obtain acid-treated Ketjen black.

[0065] (2) Hydroxyl functionalization of Ketjen black surface:

[0066] a) Weigh 50 mg of acid-treated Ketjen Black and evenly disperse it in 10 mL of Tris-HCl (pH 8.5).

[0067] b) Then, 5 mg of dopamine hydrochloride was added, and after magnetic stirring for 3 h, the mixture was washed with deionized water, anhydrous ethanol, and Tris-HCl (pH 7.0), respectively.

[0068] c) 0.35 g of dextran (T-40) was weighed and dissolved in 7 mL of deionized water to obtain a dextran solution.

[0069] d) The washed Ketjen black was redispersed in 10 mL of Tris-HCl (pH 7.0), and the dextran solution was added and reacted in an oil bath at 35° C. for 17 h.

[0070] e) After the reaction is completed, wash the mixture by centrifugation with deionized water and anhydrous ethanol for three times each, vacuum dry for 24 hours, and collect the samples.

[0071] (3) Preparation of surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst:

[0072] a) Weigh 8 mg of the sample prepared in (2) above, disperse it in 12 mL of ethylene glycol, and sonicate at low temperature for 30

[0073] min or above.

[0074] b) Add 14 mg of potassium tetrachloroplatinate and 42 mg of nickel nitrate, and continue low-temperature ultrasonication for more than 30 min.

[0075] c) Add 120 mg of ascorbic acid and stir under magnetic stirring at 100°C for 12 hours. After the reaction is completed, wash with deionized water for 2 to 3 times by centrifugation and dry in vacuum for 24 hours to obtain the surface hydroxylated platinum nickel bimetallic seawater hydrogen production catalyst PtNiNC-OH 0.35 .

[0076] Comparative Example 1

[0077] Preparation method of unmodified platinum-nickel alloy catalyst PtNiNC:

[0078] (1) Weigh 8 mg of Ketjen black and disperse it in 12 mL of ethylene glycol. Ultrasonicate at low temperature for more than 30 min.

[0079] (2) Add 14 mg of potassium tetrachloroplatinate and 42 mg of nickel nitrate, and continue low-temperature ultrasonication for more than 30 min.

[0080] (3) 120 mg of ascorbic acid was added and the mixture was reacted at 100° C. with magnetic stirring for 12 h. After the reaction was completed, the mixture was washed 2 to 3 times with deionized water by centrifugation and dried in vacuum for 24 h to obtain an unmodified platinum-nickel alloy catalyst PtNiNC.

[0081] Comparative Example 2

[0082] The HER performance test was carried out by using a commercial PtC catalyst instead of the catalyst in Example 1, Example 2, Example 3 and Comparative Example 1.

[0083] The specific implementation steps are as follows:

[0084] Step 1: Add 4 mg of the catalysts in Example 1, Example 2, Example 3 and Comparative Example 1 and the commercial PtC catalyst in Comparative Example 2 to a mixed solution of 720 μL of isopropanol and 80 μL of Nafion solution, and ultrasonically disperse for 30 to 60 minutes to obtain a uniformly dispersed slurry.

[0085] Step 2: Apply 800 μL of slurry to an area of ​​4.0 cm 2 The working electrode was obtained by drying on the hydrophilic carbon paper under a baking lamp.

[0086] Electrochemical testing

[0087] The PtNiNC-OH of Example 1, Example 2, Example 3, Comparative Example 1, and Comparative Example 2 0.15 、PtNiNC-OH 0.25 、PtNiNC-OH 0.35 The electrochemical performance of PtNiNC and commercial PtC catalysts was tested by an electrochemical workstation, and the electrochemical workstation used was Donghua electrochemical workstation, model DH7002A. The specific method is as follows:

[0088] The treated seawater solution was used as the electrolyte, and a three-electrode system was used to prepare the PtNiNC-OH 0.15 , PtNiNC-OH prepared in Example 2 0.25 , PtNiNC-OH prepared in Example 3 0.35 , PtNiNC prepared in Comparative Example 1, PtC prepared in Comparative Example 2 were used as working electrodes, mercury oxide electrode was used as reference electrode, and graphite electrode was used as counter electrode, and their linear sweep voltammetric curves were tested.

[0089] HER performance test:

[0090] The linear sweep voltammetry was used to characterize the 0.15 、PtNiNC-OH 0.25 、PtNiNC-OH 0.35 The HER performance test of PtNiNC was carried out, and the HER polarization curve (LSV diagram) obtained was as follows: Figure 4 As shown in the figure, the current density of PtNiNC-OH0.25 can reach 4200mAcm -2 , at the same overpotential (609mV), the performance is nearly 3 times that of commercial PtC (1500mAcm -2 ). At the same time, at 100mAcm -2 At a current density of 0.25 The overpotential of PtC is 31.88 mV, while the overpotential of commercial PtC is 79.31 mV.

[0091] In summary, the surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst prepared by the present invention has a water electrolysis performance that is significantly better than the precious metal catalyst PtC on the market. At the same time, the catalytic activity and stability of this catalyst at high current density are very excellent, which is conducive to industrial application in the electrolytic hydrogen production industry.

[0092] The description and practice disclosed in the present invention are easy to think and understand for ordinary technicians in the technical field, and several improvements and modifications can be made without departing from the principles of the present invention. Therefore, modifications or improvements made without departing from the spirit of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst, characterized in that: The specific steps are as follows: Step 1, synthesis of acid-treated Ketjen black: weigh a certain amount of Ketjen black and evenly disperse it in an acidic solution prepared by hydrochloric acid, nitric acid and deionized water, then react for 15 to 24 hours under the combined action of oil bath heating and magnetic stirring, then filter and centrifuge and wash several times until the washing solution is neutral, and vacuum dry to obtain the acid-treated Ketjen black; Step 2, hydroxyl functionalization of Ketjen black surface: The acid-treated Ketjen black was uniformly dispersed in a Tris-HCl buffer solution at pH 8.5, and then dopamine hydrochloride was added to the system and magnetically stirred for 3 hours. After multiple washings, it was dispersed again in a Tris-HCl buffer solution at pH 7.0, and dextran was added as a hydroxylation agent. The reaction was carried out in an oil bath for 17 hours, and the samples were washed by centrifugation, vacuum dried, and collected. Step 3, preparation of surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst: the sample prepared in the above step 2 is evenly dispersed in ethylene glycol, and then platinum and nickel metal salt precursor solutions are added to the system, and ultrasound is continued; then ascorbic acid is added as a reducing agent, and the reaction is carried out in a high-temperature oil bath for 12 hours under magnetic stirring. After the reaction is completed, the surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst is obtained by centrifugal washing and vacuum drying.

2. The method for preparing a surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst according to claim 1, characterized in that: In the step 1, the amount of Ketjen black is 0.5 g, the amount of hydrochloric acid is 35 mL, the amount of nitric acid is 35 mL, and the amount of deionized water is 70 mL.

3. The method for preparing a surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst according to claim 1, characterized in that: In the step 1, the oil bath temperature is 90-100° C., and the cleaning condition is deionized water washing, which is repeated 4-5 times.

4. The method for preparing a surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst according to claim 1, characterized in that: In the step 2, the amount of acid-treated Ketjen black is 50 mg, the amount of Tris-HCl buffer with a pH of 8.5 is 10 mL, the amount of dopamine hydrochloride is 5 mg, the amount of dextran is 50-350 mg, and the amount of Tris-HCl buffer with a pH of 7.0 is 10 mL.

5. The method for preparing a surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst according to claim 1, characterized in that: In step 2, the oil bath temperature is 30-40°C, and the magnetic stirring speed is 400-410 r min -1 , the vacuum drying time is 20 to 24 hours.

6. The method for preparing a surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst according to claim 1, characterized in that: In step 3, the amount of sample used is 8 mg, the amount of ethylene glycol used is 10-12 mL, the platinum metal salt precursor is potassium tetrachloroplatinate, the amount of which is 14 mg, the nickel metal salt precursor is nickel nitrate, the amount of which is 42 mg, and the amount of ascorbic acid is 120 mg.

7. The method for preparing a surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst according to claim 1, characterized in that: In step 3, the ultrasonic temperature is 0-20°C, the oil bath temperature is 90-100°C, and the magnetic stirring speed is 400-410 r min -1 .

8. Use of a surface hydroxylated platinum-nickel bimetallic seawater hydrogen production catalyst obtained by the preparation method according to any one of claims 1 to 7 in a hydrogen evolution reaction.

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