A green preparation method for cobalt-nickel-iron nanocage ternary hydrogen production electrocatalyst

Abstract

The invention discloses a green preparation method of a cobalt-nickel-iron nanocage ternary hydrogen production electrocatalyst. The technical scheme is as follows: S1, dispersing ZIF-67 in ethanol, placing the solution in an ultrasonic oscillator, ultrasonically dispersing until completely dissolved, and stirring to uniformly disperse it; S2, dispersing a soluble nickel salt in ethanol, and slowly adding the solution obtained in step a; S3, stirring the solution obtained in step S2 for a certain time, and collecting the obtained solid product; S4, repeatedly washing the solid obtained in step S3 with ethanol and drying it; S5, dispersing the powder obtained in step S4 in methanol; S6, taking a soluble ferrous salt in methanol and adding it to the solution obtained in step S5; S7, quickly stirring and drying the solution obtained in step S6 to obtain a solid CoNiLDH / FeOOH powder. The invention has the advantages of simple process flow, mild reaction conditions, common synthetic materials, green and low-toxic reagents, and environmental friendliness.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials and electrocatalytic materials, and in particular to a green preparation method of a cobalt-nickel-iron nanocage ternary hydrogen-producing electrocatalyst. Background Art

[0002] Hydrogen energy, as an environmentally friendly energy source that has received widespread attention, has the advantages of high energy density and being green and environmentally friendly. The only combustion product is water, which is in line with the global goal of controlling carbon emissions. However, current hydrogen production methods have some shortcomings. Traditional methods use fossil energy as raw materials, and the hydrogen produced contains impurities such as sulfides. Carbon emissions are also generated during the preparation process, which is not in line with the concept of green environmental protection. Electrolysis of water to produce hydrogen as a green and environmentally friendly method has many advantages, such as: high product purity, no carbon dioxide production during the preparation process, and recyclable. The current problem faced by water electrolysis technology is excessive energy consumption. Platinum, as an excellent hydrogen evolution electrocatalyst, can effectively reduce energy consumption, but the cost is too high. Therefore, the development of a low-cost, high-catalytic performance hydrogen evolution electrocatalyst is the current mainstream research direction.

[0003] Layered double hydroxide (LDH) is an excellent transition metal oxide hydrogen evolution electrocatalyst with positively charged metal hydroxide layers and charge-compensating anions between the layers. The large distance between the two layers can provide more active sites for the catalytic process and it has high activity in alkaline electrolytes. However, due to its poor conductivity and limited active surface area, it is easy to agglomerate, reducing the active sites and thus affecting its performance.

[0004] The existing modification of layered double hydroxides is mainly achieved through transition metal doping. Metal doping can adjust the electronic structure of the material and form defects, thereby enhancing the material's conductivity and catalytic activity, and improving the material's catalytic hydrogen evolution ability. Modification methods include heat treatment, plasma etching, chemical reduction, etc., but these methods have the disadvantages of high energy consumption, high cost, long process, and some reagents will cause environmental pollution. Summary of the Invention

[0005] To this end, the present invention provides a green preparation method for a cobalt-nickel-iron nanocage ternary hydrogen-producing electrocatalyst. By doping ZIF-67 with nickel and iron, the synthesis of submicron-scale CoNiLDH / FeOOH hollow nanocage materials is achieved to solve the problems of high energy consumption, high cost, long process, and environmental pollution caused by some reagents.

[0006] In order to achieve the above objectives, the present invention provides the following technical solution: a green preparation method of a cobalt-nickel-iron nanocage ternary hydrogen production electrocatalyst, the specific steps of which are as follows:

[0007] S1. Weigh 0.1-0.5 g of ZIF-67 and disperse it in 80-100 mL of ethanol. Place the above solution in an ultrasonic oscillator, ultrasonically disperse it until it is completely dissolved and stir it to make it uniformly dispersed to obtain a mixed solution a.

[0008] S2. Disperse 0.2-0.6 g of a soluble nickel salt in 15-25 mL of ethanol, and slowly add the mixed solution a obtained in step S1 above, stirring slowly during the addition process to obtain a mixed solution b;

[0009] S3, placing the mixed solution b obtained in the above step S2 into a reactor, stirring at a speed of 400-800 rpm for 60-120 min, and collecting the obtained solid product;

[0010] S4, repeatedly washing the solid product obtained in the above step S3 with ethanol, and then drying at 30-50° C. for 9-15 hours to obtain a powder;

[0011] S5, taking 0.1-0.4 g of the powder obtained in the above step S4, dispersing it in 7.5 mL of methanol and mixing it evenly to obtain a mixed solution c;

[0012] S6, take 0.2-0.8g of soluble ferrous salt and dissolve it in 5mL of methanol, mix it evenly, and then add it to the mixed solution c obtained in the above step S5;

[0013] S7. The mixed solution c obtained in the above step S6 is quickly stirred and dried to obtain a solid tri-metal-based hydrogen evolution electrocatalyst CoNiLDH / FeOOH powder.

[0014] Preferably, the stirring time in step S1 is 20 to 40 minutes.

[0015] Preferably, the soluble nickel salt in step S2 includes nickel nitrate and nickel acetate.

[0016] Preferably, in step S4, the solid product is repeatedly washed with ethanol at least 5 times.

[0017] Preferably, the soluble ferrous salt in step S6 includes ferrous chloride and ferrous sulfate.

[0018] Preferably, in step S7, the mixed solution c is rapidly stirred for 2 to 6 hours.

[0019] The embodiments of the present invention have the following advantages:

[0020] The method has the advantages of simple process flow, mild reaction conditions, common synthetic materials, green and low-toxic reagents, and environmental friendliness. The synthesized CoNiLDH / FeOOH powder has a microstructure of hollow nanocages with uniform morphology. The FeOOH-modified hollow nanocage structure can provide sufficient surface area for the attachment of active sites and sufficient space inside the material to accommodate electrolytes, providing a suitable place for the occurrence of hydrogen evolution reaction. The strong interfacial interaction between FeOOH and CoNiLDH also further promotes mass transfer and charge transfer, showing excellent catalytic performance in the catalytic hydrogen production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other implementation drawings based on the provided drawings without inventive effort.

[0022] The structures, proportions, sizes, etc. illustrated in this specification are intended only to complement the contents disclosed herein and to facilitate understanding and reading by persons familiar with the art. They are not intended to limit the conditions under which the present invention may be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in sizes, without affecting the efficacy and objectives of the present invention, shall still fall within the scope of the technical contents disclosed herein.

[0023] Figure 1 This is a scanning electron microscope (SEM) image of the CoNiLDH / FeOOH hollow nanocage obtained in Example 3 provided by the present invention;

[0024] Figure 2 This is a linear sweep voltammetry (LSV) diagram of the hydrogen evolution reaction of Example 3 provided by the present invention. DETAILED DESCRIPTION

[0025] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0026] Implementation 1:

[0027] The present invention provides a green preparation method of a cobalt-nickel-iron nanocage ternary hydrogen production electrocatalyst, which specifically comprises the following steps:

[0028] S1. Weigh 0.1-0.5 g of ZIF-67 and disperse it in 80 mL of ethanol. Place the above solution in an ultrasonic oscillator, ultrasonically disperse it until it is completely dissolved, and stir it for 20-40 minutes to uniformly disperse it to obtain a mixed solution a.

[0029] S2. Dispersing 0.2-0.6 g of a soluble nickel salt in 15 mL of ethanol, slowly adding the soluble nickel salt (nickel nitrate and nickel acetate) to the mixed solution a obtained in step S1 above, and slowly stirring during the addition process to obtain a mixed solution b;

[0030] S3, placing the mixed solution b obtained in the above step S2 into a reactor, stirring at a speed of 400-800 rpm for 60-120 min, and collecting the obtained solid product;

[0031] S4, repeatedly washing the solid product obtained in the above step S3 with ethanol for at least 5 times, and then drying at 30-50° C. for 9-15 hours to obtain a powder;

[0032] S5, taking 0.1-0.4 g of the powder obtained in the above step S4, dispersing it in 7.5 mL of methanol and mixing it evenly to obtain a mixed solution c;

[0033] S6. Take 0.2-0.8 g of soluble ferrous salt (ferrous chloride and ferrous sulfate) and dissolve it in 5 mL of methanol. After mixing evenly, add it to the mixed solution c obtained in the above step S5;

[0034] S7. The mixed solution c obtained in the above step S6 is rapidly stirred for 2 to 6 hours, and the solid obtained by drying is a tri-metallic hydrogen evolution electrocatalyst CoNiLDH / FeOOH powder.

[0035] Implementation 2:

[0036] The present invention provides a green preparation method of a cobalt-nickel-iron nanocage ternary hydrogen production electrocatalyst, which specifically comprises the following steps:

[0037] S1. Weigh 0.1-0.5 g of ZIF-67 and disperse it in 90 mL of ethanol. Place the above solution in an ultrasonic oscillator, ultrasonically disperse it until it is completely dissolved, and stir it for 20-40 minutes to uniformly disperse it to obtain a mixed solution a.

[0038] S2. Dispersing 0.2-0.6 g of a soluble nickel salt in 20 mL of ethanol, slowly adding the soluble nickel salt (nickel nitrate and nickel acetate) to the mixed solution a obtained in step S1 above, and slowly stirring during the addition process to obtain a mixed solution b;

[0039] S3, placing the mixed solution b obtained in the above step S2 into a reactor, stirring at a speed of 400-800 rpm for 60-120 min, and collecting the obtained solid product;

[0040] S4, repeatedly washing the solid product obtained in the above step S3 with ethanol for at least 5 times, and then drying at 30-50° C. for 9-15 hours to obtain a powder;

[0041] S5, taking 0.1-0.4 g of the powder obtained in the above step S4, dispersing it in 7.5 mL of methanol and mixing it evenly to obtain a mixed solution c;

[0042] S6. Take 0.2-0.8 g of soluble ferrous salt (ferrous chloride and ferrous sulfate) and dissolve it in 5 mL of methanol. After mixing evenly, add it to the mixed solution c obtained in the above step S5;

[0043] S7. The mixed solution c obtained in the above step S6 is rapidly stirred for 2 to 6 hours, and the solid obtained by drying is a tri-metallic hydrogen evolution electrocatalyst CoNiLDH / FeOOH powder.

[0044] Implementation 3:

[0045] Refer to the attached Figure 1-2 The present invention provides a green preparation method of a cobalt-nickel-iron nanocage ternary hydrogen production electrocatalyst, and the specific steps are as follows:

[0046] S1. Weigh 0.1-0.5 g of ZIF-67 and disperse it in 100 mL of ethanol. Place the above solution in an ultrasonic oscillator, ultrasonically disperse it until it is completely dissolved, and stir it for 20-40 minutes to uniformly disperse it to obtain a mixed solution a.

[0047] S2. Dispersing 0.2-0.6 g of a soluble nickel salt in 25 mL of ethanol, slowly adding the soluble nickel salt (nickel nitrate and nickel acetate) to the mixed solution a obtained in step S1 above, and slowly stirring during the addition process to obtain a mixed solution b;

[0048] S3, placing the mixed solution b obtained in the above step S2 into a reactor, stirring at a speed of 400-800 rpm for 60-120 min, and collecting the obtained solid product;

[0049] S4, repeatedly washing the solid product obtained in the above step S3 with ethanol for at least 5 times, and then drying at 30-50° C. for 9-15 hours to obtain a powder;

[0050] S5, taking 0.1-0.4 g of the powder obtained in the above step S4, dispersing it in 7.5 mL of methanol and mixing it evenly to obtain a mixed solution c;

[0051] S6. Take 0.2-0.8 g of soluble ferrous salt (ferrous chloride and ferrous sulfate) and dissolve it in 5 mL of methanol. After mixing evenly, add it to the mixed solution c obtained in the above step S5;

[0052] S7. The mixed solution c obtained in the above step S6 is rapidly stirred for 2 to 6 hours, and the solid obtained by drying is a tri-metallic hydrogen evolution electrocatalyst CoNiLDH / FeOOH powder.

[0053] Embodiment 3 is the best embodiment of the present invention.

[0054] In this embodiment, the CoNiLDH / FeOOH hollow nanocage material of the present invention was successfully synthesized and its structure was characterized;

[0055] from Figure 1 It can be seen that the hollow nanocage structure of CoNiLDH / FeOOH was successfully synthesized and has uniform size;

[0056] from Figure 2 It can be seen that the hydrogen evolution process of this material is at 10mA / cm 2 The overpotential under current density is 121 mV. The lower the overpotential, the better the catalytic performance of the material for the hydrogen evolution reaction. Therefore, this material has good catalytic hydrogen evolution ability.

[0057] The above description is merely a preferred embodiment of the present invention. Anyone skilled in the art may utilize the above-described technical solutions to modify the present invention or modify it into an equivalent technical solution. Therefore, any simple modification or equivalent replacement based on the technical solution of the present invention falls within the scope of protection claimed by the present invention.

Claims

1. A green preparation method of a cobalt-nickel-iron nanocage ternary hydrogen production electrocatalyst, characterized by: The specific steps are as follows: S1. Weigh 0.1-0.5 g of ZIF-67 and disperse it in 80-100 mL of ethanol. Place the above solution in an ultrasonic oscillator, ultrasonically disperse it until it is completely dissolved and stir it to make it uniformly dispersed to obtain a mixed solution a. S2. Disperse 0.2-0.6 g of a soluble nickel salt in 15-25 mL of ethanol, and slowly add the mixed solution a obtained in step S1 above, stirring slowly during the addition process to obtain a mixed solution b; S3, placing the mixed solution b obtained in the above step S2 into a reactor, stirring at a speed of 400-800 rpm for 60-120 min, and collecting the obtained solid product; S4, repeatedly washing the solid product obtained in the above step S3 with ethanol, and then drying at 30-50° C. for 9-15 hours to obtain a powder; S5, taking 0.1-0.4 g of the powder obtained in the above step S4, dispersing it in 7.5 mL of methanol and mixing it evenly to obtain a mixed solution c; S6, take 0.2-0.8g of soluble ferrous salt and dissolve it in 5mL of methanol, mix it evenly, and then add it to the mixed solution c obtained in the above step S5; S7. The mixed solution c obtained in the above step S6 is quickly stirred and dried to obtain a solid tri-metal-based hydrogen evolution electrocatalyst CoNiLDH / FeOOH powder.

2. The green preparation method of a cobalt-nickel-iron nanocage ternary hydrogen production electrocatalyst according to claim 1, characterized in that: In the step S1, stirring is performed for 20 to 40 minutes.

3. The green preparation method of a cobalt-nickel-iron nanocage ternary hydrogen production electrocatalyst according to claim 1, characterized in that: The soluble nickel salt in step S2 includes nickel nitrate and nickel acetate.

4. The green preparation method of a cobalt-nickel-iron nanocage ternary hydrogen production electrocatalyst according to claim 1, characterized in that: In step S4, the solid product is repeatedly washed with ethanol at least 5 times.

5. The green preparation method of a cobalt-nickel-iron nanocage ternary hydrogen production electrocatalyst according to claim 1, characterized in that: The soluble ferrous salt in step S6 includes ferrous chloride and ferrous sulfate.

6. The green preparation method of a cobalt-nickel-iron nanocage ternary hydrogen production electrocatalyst according to claim 1, characterized in that: In step S7, the mixed solution c is rapidly stirred for 2 to 6 hours.

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