Method for preparing Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst based on corrosion engineering and its application

Abstract

The present invention discloses a method for preparing Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst based on corrosion engineering and its application. The specific process is: placing foam metal in anhydrous ethanol, dilute hydrochloric acid and deionized water for ultrasonic cleaning in sequence to obtain material A; adding NiCl2, AlCl3 and RuCl3 into deionized water in sequence, then placing material A in the mixed solution and stirring, stirring and reacting at room temperature to obtain material B; washing material B with deionized water and anhydrous ethanol in sequence, and then drying in a blast drying oven at 80°C to finally obtain the target product, Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst. The high-efficiency hydrogen evolution electrocatalyst prepared by the present invention has a high efficiency at 1 mol L –1 In KOH solution, only 85~110mV overpotential is required to reach 100mA cm –2 current density, and has excellent electrocatalytic hydrogen evolution performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of electrocatalysts for hydrogen evolution by electrolysis of water, and particularly relates to a method for preparing Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalysts based on corrosion engineering and applications thereof. Background Art

[0002] The hydrogen evolution reaction (HER) plays an important role in hydrogen production by water electrolysis. However, the slow kinetics of HER require efficient electrocatalysts to accelerate the process. Precious metal platinum-based materials are the benchmark electrocatalysts for HER, but their high cost and scarcity seriously hinder their widespread application in water electrolysis. In recent years, various non-precious metal-based nanomaterials, such as sulfides, phosphides, carbides and hydroxides, have been successfully developed for HER. Among them, nickel iron hydroxide (NiFe-OH) is widely used as an electrocatalytic material due to its low cost, abundant resources, flexible structure and composition. However, due to the poor inherent conductivity of hydroxide and the weak adsorption of hydrogen on the catalyst surface, it leads to a large hydrogen evolution overpotential and sluggish kinetics. Its performance in alkaline solution is difficult to meet application requirements (10mA cm –2 Therefore, it is particularly important to develop an effective strategy to enhance the HER catalytic activity of NiFe-OH.

[0003] Since ruthenium (Ru) has a similar binding strength with hydrogen as Pt and its cost is relatively low (the cost per unit mass is only 5% of that of Pt), it has been widely introduced into NiFe-OH to improve the weak hydrogen adsorption energy of the hydroxide. In addition, it is reported that the introduction of a third non-precious metal (such as Al, Zn, V and W, etc.) into NiFe-OH can adjust the local coordination environment and electronic configuration, thereby further improving its electrocatalytic activity. Powder catalysts are commonly used for hydrogen production by electrolysis of water, but binders (such as Nafion solution) are required in the process of preparing hydrogen evolution electrodes. The use of binders will cause some active centers to be masked and the charge transfer resistance to increase, thereby reducing the catalytic performance of the catalyst. Compared with powder catalysts, self-supporting electrocatalysts have attracted widespread attention due to their high electrical conductivity, rich porous structure and high specific surface area. However, the preparation of self-supporting NiFe-OH hydrogen evolution catalysts usually requires a complex reaction process and harsh reaction conditions. Recently, corrosion engineering has become a common method for preparing self-supporting electrodes based on metal foams (such as Ni foam, Fe foam, NiFe foam, and CoNi foam) due to its advantages such as low cost, good regulation, and simple synthesis. Therefore, the present invention utilizes metal corrosion engineering to prepare a highly active and stable hydrogen evolution electrocatalyst using NiFe foam as a substrate and co-doping NiFe-OH with Ru and Al. Summary of the Invention

[0004] The technical problem solved by the present invention is to provide a simple and efficient method for preparing Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst based on corrosion engineering. The method is carried out at room temperature and does not require complicated operation steps. First, foamed NiFe is immersed in a mixed solution of "NiCl2-AlCl3-RuCl3" and stirred. Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst are prepared by the method. 3+ With strong oxidizing properties, the metal undergoes spontaneous corrosion reaction, and the in-situ grown corrosion layer covers the surface of the NiFe substrate, among which Al 3+ Can react with the oxygen reduction reaction product OH in the cathode microregion – The combination forms a passivation film, thereby slowing down the corrosion rate of the metal, and finally successfully synthesized Ru and Al co-doped NiFe-OH nanosheet array hydrogen evolution electrocatalyst, which has excellent hydrogen evolution reaction performance and can be used in the hydrogen evolution reaction of water electrolysis.

[0005] The present invention adopts the following technical solution to solve the above technical problems, and is a method for preparing Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst based on corrosion engineering, which is characterized by the specific process:

[0006] Step S1: placing the foam metal in anhydrous ethanol, dilute hydrochloric acid and deionized water in sequence for ultrasonic cleaning to remove organic molecules and oxides on the surface of the foam metal to obtain material A;

[0007] Step S2: NiCl2, AlCl3 and RuCl3 are added to deionized water in sequence, and stirred with a magnetic stirrer to obtain a mixed solution. Then, the material A obtained in step S1 is placed in the mixed solution, and stirred at room temperature to react to obtain material B;

[0008] Step S3: The material B obtained in step S2 is washed with deionized water and anhydrous ethanol in sequence, and then dried in a forced air drying oven at 80° C. to finally obtain the target product, a hydrogen evolution electrocatalyst.

[0009] It is further defined that the foam metal in step S1 is foam NiFe with a size of 1 to 6 cm 2 The ultrasonic cleaning time of the foam metal in anhydrous ethanol, dilute hydrochloric acid and deionized water is 10 min, 25 min and 5 min, respectively.

[0010] It is further defined that the molar concentration of NiCl2 in the mixed solution in step S2 is 50-200 mM, the molar concentration of AlCl3 is 50-200 mM, and the molar concentration of RuCl3 is 1-3 mM.

[0011] It is further defined that the rotation speed of the magnetic stirrer in step S2 is 100-300 rpm, and the stirring time is 3-9 hours.

[0012] The method for preparing Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst based on corrosion engineering of the present invention is characterized by the following specific steps:

[0013] Step S1: placing NiFe foam in anhydrous ethanol, dilute hydrochloric acid, and deionized water for ultrasonic cleaning for 10 min, 25 min, and 5 min, respectively, to remove organic molecules and oxides on the metal surface, thereby obtaining material A;

[0014] Step S2: NiCl2, AlCl3, and RuCl3 were sequentially added to deionized water and stirred thoroughly with a magnetic stirrer to obtain a mixed solution, wherein the molar concentration of NiCl2 in the mixed solution was 100 mM, the molar concentration of AlCl3 was 100 mM, and the molar concentration of RuCl3 was 2 mM. Then, the material A obtained in step S1 was placed in the mixed solution, and the mixture was stirred at room temperature for 9 hours to obtain material B;

[0015] Step S3: The material B obtained in step S2 was washed with deionized water and anhydrous ethanol in sequence, and then dried in a forced air drying oven at 80°C for 3 h to obtain the target product, a hydrogen evolution electrocatalyst having a nanosheet array structure. The structure is conducive to the migration of substances in the catalytic reaction and provides abundant active sites. The prepared hydrogen evolution electrocatalyst has a high activity at 1 mol L –1 In KOH solution, only 85-110 mV overpotential is required to reach 100 mA cm –2 Current density, and has excellent electrocatalytic hydrogen evolution performance.

[0016] The invention relates to the use of the Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst in the hydrogen evolution reaction by electrolysis of water.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] 1. The present invention utilizes the spontaneous corrosion process of metals at room temperature and immerses the foamed NiFe in a mixed solution of "NiCl2-AlCl3-RuCl3". The synthesis method is simple and efficient and does not require complicated operating steps;

[0019] 2. The present invention utilizes corrosion engineering to prepare hydrogen evolution electrocatalyst, wherein Al 3+ Can react with the oxygen reduction reaction product OH in the cathode microregion – The combination forms a passivation film, which is conducive to the uniform growth of the corrosion layer. The active material is firmly attached to the substrate and is not easy to fall off during the electrolysis process.

[0020] 3. The Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst prepared by the present invention has a unique morphology, namely a nanosheet array structure, which is conducive to the migration of substances in the catalytic reaction and provides abundant active sites;

[0021] 4. The Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst prepared by the present invention is –1 In KOH solution, only 85-110 mV overpotential is required to reach 100 mA cm –2 Current density, and has excellent electrocatalytic hydrogen evolution performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a scanning electron microscope image of the target product C3 prepared in Example 3;

[0023] Figure 2 Electrochemical impedance spectroscopy (EIS) of target products C1-C3 prepared in Examples 1-3;

[0024] Figure 3 The linear sweep voltammograms of the target products C1-C3 prepared in Examples 1-3 are shown;

[0025] Figure 4 This is the corrosion polarization curve of the target product C2-C3 prepared in Example 2-3. DETAILED DESCRIPTION

[0026] The above contents of the present invention are further described in detail below through examples, but this should not be understood as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above contents of the present invention fall within the scope of the present invention.

[0027] Example 1

[0028] Step S1: NiFe foam (size 2×2 cm 2 ) was sequentially placed in anhydrous ethanol, dilute hydrochloric acid and deionized water for ultrasonic cleaning for 10 min, 25 min and 5 min respectively to remove organic molecules and oxides on the metal surface to obtain material A1;

[0029] Step S2: NiCl2 was added to 30 mL of deionized water and stirred with a magnetic stirrer to obtain a mixed solution, wherein the molar concentration of NiCl2 in the mixed solution was 100 mM. Then, the material A1 obtained in step S1 was placed in the mixed solution and stirred at room temperature for 9 h to obtain material B1;

[0030] Step S3: The material B1 obtained in step S2 was washed with deionized water and anhydrous ethanol in sequence, and then dried in a forced air drying oven at 80° C. for 2 h to obtain the target product C1.

[0031] Example 2

[0032] Step S1: NiFe foam (size 2×2 cm 2) were sequentially placed in anhydrous ethanol, dilute hydrochloric acid and deionized water for ultrasonic cleaning for 10 min, 25 min and 5 min respectively to remove organic molecules and oxides on the metal surface to obtain material A2;

[0033] Step S2: NiCl2 and RuCl3 were added to 30 mL of deionized water and stirred with a magnetic stirrer to obtain a mixed solution, wherein the molar concentration of NiCl2 in the mixed solution was 100 mM and the molar concentration of RuCl3 was 2 mM. Then, the material A2 obtained in step S1 was placed in the mixed solution and stirred at room temperature for 9 h to obtain material B2;

[0034] Step S3: The material B2 obtained in step S2 was washed with deionized water and anhydrous ethanol, and then dried in a forced air drying oven at 80° C. for 2 h to obtain the target product C2.

[0035] Example 3

[0036] Step S1: NiFe foam (size 2×2 cm 2 ) was sequentially placed in anhydrous ethanol, dilute hydrochloric acid and deionized water for ultrasonic cleaning for 10 min, 25 min and 5 min respectively to remove organic molecules and oxides on the metal surface to obtain material A3;

[0037] Step S2: NiCl2, AlCl3, and RuCl3 were added to 30 mL of deionized water and stirred thoroughly with a magnetic stirrer to obtain a mixed solution, wherein the molar concentration of NiCl2 in the mixed solution was 100 mM, the molar concentration of AlCl3 was 100 mM, and the molar concentration of RuCl3 was 2 mM. Then, the material A3 obtained in step S1 was placed in the mixed solution and stirred at room temperature for 9 hours to obtain material B3;

[0038] Step S3: The material B3 obtained in step S2 was washed with deionized water and anhydrous ethanol, and then dried in a forced air drying oven at 80° C. for 3 h to obtain the target product C3.

[0039] Example 4

[0040] Cut the target product C3 to a size of 0.5×1 cm 2 As working electrodes, the target products C1, C2, and NiFe foam (NFF) were prepared using the same method and used for comparison with the target product C3. All electrochemical tests were performed using a three-electrode system. During the linear sweep voltammetry (LSV) test, a platinum electrode clamp was used to fix the hydrogen evolution electrode as the working electrode (effective area 0.4 × 0.5 cm 2 ), Hg / HgO electrode and carbon rod were used as reference electrode and counter electrode respectively, and the electrolyte was 1 molL –1 The scan rate during testing was 5 mV s-1 The scanning range is 0~-0.4V (vs.RHE). The catalytic performance of the target products in all examples are as follows: Figure 3 The linear sweep voltammetry curve shown is at 100 mA cm –2 At the current density, the overpotentials of the target products C1, C2 and C3 samples prepared in all examples were 394 mV, 191 mV and 85 mV, respectively.

[0041] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst based on corrosion engineering, characterized in that The specific process is: Step S1: The foam metal is placed in anhydrous ethanol, dilute hydrochloric acid and deionized water for ultrasonic cleaning in sequence to remove organic molecules and oxides on the surface of the foam metal to obtain material A, wherein the foam metal is foam NiFe with a size of 1 to 6 cm 2 ; Step S2: NiCl2, AlCl3 and RuCl3 are sequentially added to deionized water, and stirred with a magnetic stirrer to obtain a mixed solution. Then, the material A obtained in step S1 is placed in the mixed solution, wherein the molar concentration of NiCl2 in the mixed solution is 50-200 mM, the molar concentration of AlCl3 is 50-200 mM, and the molar concentration of RuCl3 is 1-3 mM. The mixture is stirred at room temperature to obtain material B; Step S3: washing the material B obtained in step S2 with deionized water and anhydrous ethanol in sequence, and then drying it in a forced air drying oven at 80° C. to finally obtain the target product, a hydrogen evolution electrocatalyst.

2. The method for preparing Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst based on corrosion engineering according to claim 1, characterized in that: The ultrasonic cleaning time of the metal foam in anhydrous ethanol, dilute hydrochloric acid and deionized water in step S1 is 10 minutes, 25 minutes and 5 minutes respectively.

3. The method for preparing Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst based on corrosion engineering according to claim 1, characterized in that: The rotation speed of the magnetic stirrer in step S2 is 100-300 rpm, and the stirring time is 3-9 h.

4. The method for preparing Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst based on corrosion engineering according to claim 1, characterized in that The specific steps are: Step S1: placing the NiFe foam in anhydrous ethanol, dilute hydrochloric acid, and deionized water for ultrasonic cleaning for 10 min, 25 min, and 5 min, respectively, to remove organic molecules and oxides on the metal surface, thereby obtaining material A; Step S2: NiCl2, AlCl3 and RuCl3 are sequentially added to deionized water and stirred with a magnetic stirrer to obtain a mixed solution, wherein the molar concentration of NiCl2 in the mixed solution is 100 mM, the molar concentration of AlCl3 is 100 mM, and the molar concentration of RuCl3 is 2 mM. Then, the material A obtained in step S1 is placed in the mixed solution, and the reaction is stirred at room temperature for 9 hours to obtain material B; Step S3: The material B obtained in step S2 was washed with deionized water and anhydrous ethanol in sequence, and then dried in a forced air drying oven at 80°C for 3 h to obtain the target product, a hydrogen evolution electrocatalyst having a nanosheet array structure. The structure is conducive to the migration of substances in the catalytic reaction and provides abundant active sites. The prepared hydrogen evolution electrocatalyst has a high activity at 1 mol L –1 In KOH solution, only 85~110mV overpotential is required to reach 100mA cm –2 Current density, and has excellent electrocatalytic hydrogen evolution performance.

5. Use of the Ru and Al co-doped NiFe-OH hydrogen evolution electrocatalyst prepared according to the method according to any one of claims 1 to 4 in the hydrogen evolution reaction by electrolysis of water.

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