CN115323395A - Self-supporting electro-catalytic hydrogen evolution catalyst electrode with strain lattice and preparation method and application thereof - Google Patents

Abstract

The invention provides a self-supporting electro-catalytic hydrogen evolution catalyst electrode with strain lattices and a preparation method and application thereof, belonging to the technical field of energy storage materials. The method comprises the following steps: mixing nickel salt, cobalt salt, molybdate, urea and water to obtain a mixed solution; and mixing the mixed solution with foamed nickel, and carrying out hydrothermal reaction to obtain the self-supporting electro-catalytic hydrogen evolution catalyst electrode with the strain crystal lattice. Aiming at the problem of low HER activity of an LDH material under an alkaline condition, the invention develops a high-activity alkaline HER catalyst, an LDH nanosheet material grown in situ on foamed nickel has lattice strain, the electronic structure of the material is adjusted under the action of Mo atom for electron through Mo element doping, the splitting energy of water molecules is reduced, in addition, mo atom and adsorbed H have stronger coupling effect, a strong Mo-H bond can be formed, H adsorption is enhanced, and the catalytic activity is further improved.

Description

A self-supporting electrocatalytic hydrogen evolution catalyst electrode with strained lattice and its preparation Methods and Applications

technical field

The invention relates to the technical field of energy storage materials, in particular to a self-supporting electrocatalytic hydrogen evolution catalyst electrode with a strained lattice and a preparation method and application thereof.

Background technique

As one of the hydrogen production technologies, electrochemical water splitting provides a sustainable way for hydrogen energy conversion and storage, which is very important to cope with the increasingly scarce fossil energy. In water electrolysis devices, the energy efficiency is closely related to the hydrogen evolution reaction (HER) on the anode and the oxygen evolution (OER) reaction on the cathode. Designing and synthesizing electrocatalysts with high activity plays a crucial role in improving energy efficiency to drive water electrolysis to produce hydrogen at low voltage. The scarcity and high price of noble metal catalyst materials currently available in practice limit their large-scale production and application in practice. Therefore, the development of inexpensive and highly efficient non-precious electrocatalysts with fast catalytic reaction kinetics is of great practical significance for improving electrocatalytic activity and durability.

Among various non-noble metal catalysts, layered double hydroxyhydroxide (LDH) catalyst materials exhibit excellent electrocatalytic performance, especially in basic OER catalysis, showing great application potential. However, the weak hydrogen adsorption of LDH electrocatalyst materials in alkaline electrolytes will lead to their slow HER catalytic kinetics and lower activity, which is unfavorable for water splitting reactions. Therefore, it is of great significance to develop inexpensive HER electrocatalysts with high catalytic activity and stability.

Contents of the invention

In view of this, the object of the present invention is to provide a self-supporting electrocatalytic hydrogen evolution catalyst electrode with a strained lattice, its preparation method and application. The self-supporting electrocatalytic hydrogen evolution catalyst electrode with strained lattice prepared by the invention has high catalytic activity.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The invention provides a method for preparing a self-supporting electrocatalytic hydrogen evolution catalyst electrode with a strained lattice, comprising the following steps:

Mix nickel salt, cobalt salt, molybdate, urea and water to obtain a mixed solution;

The mixed solution is mixed with the nickel foam, and the hydrothermal reaction is carried out to obtain the self-supporting electrocatalytic hydrogen evolution catalyst electrode with the strained lattice.

Preferably, the molar ratio of the nickel salt to molybdate is (1-3):1.

Preferably, the molar ratio of the cobalt salt to the molybdate is (1-3):1.

Preferably, the molar ratio of metal salt to urea is (1-10):1, and the metal salt includes nickel salt, cobalt salt and molybdate.

Preferably, the mixed solution also contains ammonium fluoride.

Preferably, the molar ratio of metal salt to ammonium fluoride is (1-10):1, and the metal salt includes nickel salt, cobalt salt and molybdate.

Preferably, the temperature of the hydrothermal reaction is 100-200° C., and the time is 4-24 hours.

Preferably, the ratio of nickel foam to metal salt is 1 cm ² : 0.1-10 mmol, and the metal salt includes nickel salt, cobalt salt and molybdate.

The present invention also provides a self-supporting electrocatalytic hydrogen evolution catalyst electrode with a strained lattice prepared by the preparation method described in the above technical solution.

The present invention also provides the application of the self-supporting electrocatalytic hydrogen evolution catalyst electrode with strained lattice described in the above technical solution as an electrocatalytic hydrogen evolution catalyst electrode.

The invention provides a preparation method of a self-supporting electrocatalytic hydrogen evolution catalyst electrode with a strained lattice, comprising the following steps: mixing nickel salt, cobalt salt, molybdate, urea and water to obtain a mixed solution; mixing the mixed The solution is mixed with the nickel foam, and the hydrothermal reaction is carried out to obtain the self-supporting electrocatalytic hydrogen evolution catalyst electrode with the strained lattice.

The present invention aims at the problem of low HER activity of LDH materials under alkaline conditions, and develops highly active alkaline HER catalysts, and the LDH nanosheet materials (including F-NiCoMo LDH and NiCoMo LDH) grown in situ on foamed nickel have lattice strain , through Mo element doping, under the action of Mo atoms donating electrons, the electronic structure of the material is adjusted, and the splitting energy of water molecules is reduced. In addition, Mo atoms and adsorbed H have a strong coupling effect, which can form a strong Mo-H bond , enhance the H adsorption, and then improve the catalytic activity.

At the same time, the preparation process of the present invention is simple, and the cost of raw materials has the advantages of low price and abundant reserves compared with noble metal catalyst materials, and the self-supporting structure avoids the adverse effect of the coating process on the catalytic activity, showing excellent electrocatalytic activity and stability .

Furthermore, F doping plays a role in adjusting the electronic structure, and F doping can greatly reduce the reaction energy barrier in the catalytic process, so that the catalytic reaction kinetics can be accelerated.

The present invention also provides a self-supporting electrocatalytic hydrogen evolution catalyst electrode with a strained lattice prepared by the preparation method described in the above technical scheme, Mo and F doping optimizes the electronic structure of the material surface, and the d-band center of the material after doping The surface of the material has a stronger adsorption of H, and Mo atoms can combine with H with a stronger Mo-H bond, which is conducive to the adsorption of H, and F doping can reduce the energy reaction barrier.

Description of drawings

Fig. 1 is the XRD pattern of the self-supporting LDH electrocatalytic HER catalyst electrode prepared by Examples 1 and 2 and the catalyst electrode prepared by Comparative Example;

Figure 2 is the SEM images of the self-supporting LDH electrocatalytic HER catalyst electrode prepared in Examples 1 and 2 and the catalyst electrode prepared in the comparative example at different magnifications, where a, b and c are the self-supporting LDH electrocatalyst electrodes prepared in the comparative example. The SEM image of the catalytic HER catalyst electrode, d, e and f are the SEM images of the self-supporting LDH electrocatalytic HER catalyst electrode prepared in Example 2, and g, h and i are the SEM images of the catalyst electrode prepared in Example 1;

Figure 3 is the TEM images of LDH nanosheets prepared in Examples 1 and 2 and Comparative Example at different magnifications, wherein a, b, and c are respectively low-magnification TEM images of NiCo LDH, NiCoMo LDH and F-NiCoMo LDH, d, e and f are high-magnification TEM images of NiCo LDH, NiCoMo LDH and F-NiCoMo LDH, respectively;

Fig. 4 is the electrocatalytic activity test performance diagram of the self-supporting LDH electrocatalytic HER catalyst electrode prepared in Examples 1 and 2 and the catalyst electrode prepared in Comparative Example;

Fig. 5 is the stability test curve of the self-supporting LDH electrocatalytic HER catalyst electrode prepared in Example 1.

Detailed ways

The invention provides a method for preparing a self-supporting electrocatalytic hydrogen evolution catalyst electrode with a strained lattice, comprising the following steps:

Mix nickel salt, cobalt salt, molybdate, urea and water to obtain a mixed solution;

The mixed solution is mixed with the nickel foam, and the hydrothermal reaction is carried out to obtain the self-supporting electrocatalytic hydrogen evolution catalyst electrode with the strained lattice.

In the present invention, unless otherwise specified, the raw materials used are all commercially available products in this field.

The invention mixes nickel salt, cobalt salt, molybdate, urea and water to obtain a mixed solution.

In the present invention, the molar ratio of the nickel salt to molybdate is preferably (1-3):1.

In the present invention, the molar ratio of the cobalt salt to the molybdate is preferably (1-3):1.

In the present invention, the molar ratio of metal salt to urea is preferably (1-10):1, and the metal salt preferably includes nickel salt, cobalt salt and molybdate.

In the present invention, the mixed solution preferably further contains ammonium fluoride.

In the present invention, the molar ratio of metal salt to ammonium fluoride is preferably (1-10):1, and the metal salt preferably includes nickel salt, cobalt salt and molybdate.

In the present invention, there is no special limitation on the specific types of the nickel salt, cobalt salt and molybdate, and the types well known to those skilled in the art can be used.

In the present invention, the function of the urea is to adjust the pH value and provide an alkaline atmosphere necessary for the reaction, and the function of the ammonium fluoride is to provide F doping while adjusting the pH value.

In the present invention, the order of mixing is preferably: first mix the nickel salt, cobalt salt, molybdate and water to obtain the first solution, then mix the urea, NH ₄ F and water to obtain the second solution. two solutions, and finally combine the first solution and the second solution to obtain the mixed solution.

After the mixed solution is obtained, in the present invention, the mixed solution and nickel foam are subjected to a hydrothermal reaction to obtain the self-supporting electrocatalytic hydrogen evolution catalyst electrode with a strained lattice.

In the present invention, the temperature of the hydrothermal reaction is preferably 100-200° C., more preferably 140-160° C., and the time is preferably 4-24 hours, more preferably 6-18 hours.

In the present invention, during the hydrothermal reaction, metal ions react with hydroxyl groups to form hydroxide nanosheets (LDH) and grow on the surface of nickel foam.

In the present invention, the ratio of nickel foam to metal salt is preferably 1 cm ² : 0.1-10 mmol, and the metal salt preferably includes nickel salt, cobalt salt and molybdate.

In the present invention, the hydrothermal reaction is preferably carried out in a hydrothermal reaction tank.

After the hydrothermal reaction is completed, the present invention preferably washes and dries the obtained hydrothermal product in sequence to obtain the self-supporting electrocatalytic hydrogen evolution catalyst electrode with strained lattice.

In the present invention, the washing is preferably carried out sequentially with water washing and ethanol washing.

In the present invention, there is no special limitation on the specific method of drying, and a method well known to those skilled in the art can be used.

The present invention also provides a self-supporting electrocatalytic hydrogen evolution catalyst electrode with a strained lattice prepared by the preparation method described in the above technical solution.

In the present invention, the structure of the self-supporting electrocatalytic hydrogen evolution catalyst electrode with a strained lattice is a hydroxide nanosheet (LDH) grown in situ on a nickel foam, and the hydroxide (LDH) nanosheet includes NiCoMo LDH, preferably F-NiCoMo LDH nanosheets.

The present invention also provides the application of the self-supporting electrocatalytic hydrogen evolution catalyst electrode with strained lattice described in the above technical solution as an electrocatalytic hydrogen evolution catalyst electrode.

The present invention has no special limitation on the specific manner of the application, and the methods well known to those skilled in the art can be adopted.

In order to further illustrate the present invention, the self-supporting electrocatalytic hydrogen evolution catalyst electrode with strained lattice provided by the present invention and its preparation method and application are described in detail below in conjunction with examples, but they should not be interpreted as limiting the protection scope of the present invention.

Example 1

Dissolve 0.058 g Ni(NO ₃ ) ₂ 6H ₂ O, 0.058 g Co(NO ₃ ) ₂ 6H ₂ O, and 0.048 g Na ₂ MoO ₄ 2H ₂ O in 20 mL of ultrapure water under magnetic stirring to configure a mixing Solution A: Dissolve 0.360g urea and 0.222g NH ₄ F in 15mL ultrapure water under magnetic stirring to prepare mixed solution B. Then, solution A and solution B were mixed together to form solution C. A 2.5cm×4cm nickel foam material was then immersed in the solution, and subjected to a hydrothermal reaction at a temperature of 140° C. for 6 hours. After the reaction was finished, it was washed with water and ethanol several times to obtain the target electrocatalyst sample (marked as F-NiCoMo LDH or F-NiCoMo LDH/NF).

Example 2

Dissolve 0.058 g Ni(NO ₃ ) ₂ 6H ₂ O, 0.058 g Co(NO ₃ ) ₂ 6H ₂ O, and 0.048 g Na ₂ MoO ₄ 2H ₂ O in 20 mL of ultrapure water under magnetic stirring to configure a mixing Solution A: Dissolve 0.360g of urea in 15mL of ultrapure water under magnetic stirring to prepare mixed solution B. Then, solution A and solution B were mixed together to form solution C. A 2.5cm×4cm nickel foam material was then immersed in the solution, and subjected to a hydrothermal reaction at a temperature of 140° C. for 6 hours. After the reaction was completed, the target electrocatalyst sample (marked as NiCoMo LDH nanosheet or NiCoMo LDH/NF) was obtained by washing with water and ethanol several times.

comparative example

Under magnetic stirring, 0.058g Ni(NO ₃ ) ₂ ·6H ₂ O and 0.058g Co(NO ₃ ) ₂ ·6H ₂ O were dissolved in 20mL ultrapure water to configure mixed solution A; under magnetic stirring, 0.360g Dissolve urea in 15mL ultrapure water to configure mixed solution B. Then, solution A and solution B were mixed together to form solution C. A 2.5cm×4cm nickel foam material was then immersed in the solution, and subjected to a hydrothermal reaction at a temperature of 140° C. for 6 hours. After the reaction was finished, it was washed with water and ethanol several times to obtain the target electrocatalyst sample (marked as NiCo LDH or NiCo LDH/NF).

Example 3

Dissolve 0.058 g Ni(NO ₃ ) ₂ 6H ₂ O, 0.058 g Co(NO ₃ ) ₂ 6H ₂ O, and 0.048 g Na ₂ MoO ₄ 2H ₂ O in 20 mL of ultrapure water under magnetic stirring to configure a mixing Solution A: Dissolve 0.360g urea and 0.222g NH ₄ F in 15mL ultrapure water under magnetic stirring to prepare mixed solution B. Then, solution A and solution B were mixed together to form solution C. A 2.5cm×4cm nickel foam material was then immersed in the solution, and subjected to a hydrothermal reaction at 180° C. for 6 hours. After the reaction, the target electrocatalyst sample was obtained by washing with water and ethanol several times.

Example 4

Dissolve 0.058 g Ni(NO ₃ ) ₂ 6H ₂ O, 0.058 g Co(NO ₃ ) ₂ 6H ₂ O, and 0.024 g Na ₂ MoO ₄ 2H ₂ O in 20 mL of ultrapure water under magnetic stirring to configure a mixing Solution A: Dissolve 0.360g urea and 0.222g NH ₄ F in 15mL ultrapure water under magnetic stirring to prepare mixed solution B. Then, solution A and solution B were mixed together to form solution C. A 2.5cm×4cm nickel foam material was then immersed in the solution, and subjected to a hydrothermal reaction at a temperature of 140° C. for 6 hours. After the reaction, the target electrocatalyst sample was obtained by washing with water and ethanol several times.

Example 5

Under magnetic stirring, 0.058g Ni(NO ₃ ) ₂ ·6H ₂ O and 0.058g Co(NO ₃ ) ₂ ·6H ₂ O were dissolved in 20mL ultrapure water to configure mixed solution A; under magnetic stirring, 0.360g Dissolve urea in 15mL ultrapure water to configure mixed solution B. Then, solution A and solution B were mixed together to form solution C. A 2.5cm×4cm nickel foam material was then immersed in the solution, and subjected to a hydrothermal reaction at a temperature of 160° C. for 6 hours. After the reaction, the target electrocatalyst sample was obtained by washing with water and ethanol several times.

The self-supporting LDH electrocatalytic HER catalyst electrodes prepared in Examples 1 and 2 and the catalyst electrodes prepared in the comparative examples were characterized and tested, as follows:

Figure 1 is the XRD pattern of the self-supporting LDH electrocatalytic HER catalyst electrode prepared in Examples 1 and 2 and the catalyst electrode prepared in a comparative example. It can be seen from Figure 1 that when molybdate is added, the crystallinity of the prepared NiCoMo LDH decreases, and the two wider (221) crystal planes and (412) crystal planes move in the positive direction, indicating that compressed crystals appear in the material. grid. When molybdate and ammonium fluoride are added at the same time, the crystal plane of the prepared F-NiCoMo LDH material shifts to the negative direction at the same time, indicating that there are both compressive and tensile lattices in the material.

Fig. 2 is the SEM image of the self-supporting LDH electrocatalytic HER catalyst electrode prepared in Examples 1 and 2 under different magnifications with the catalyst electrode prepared in the comparative example, wherein a, b and c are self-supporting LDH electrocatalyst electrodes prepared in the comparative example The SEM figure of the catalytic HER catalyst electrode, d, e and f are the SEM figures of the self-supporting LDH electrocatalytic HER catalyst electrode prepared in Example 2, g, h and i are the SEM figures of the catalyst electrode prepared in Example 1, from the figure In a, b, and c, it can be seen that 2D ultrathin NiCo-LDH nanosheets with smooth surface grow vertically on the surface of nickel foam, and the uniformly distributed NiCo-LDH nanosheet arrays are interconnected to form a strong honeycomb structure. From Figures d, e, and f, it can be seen that when molybdate is contained, the prepared NiCoMo LDH catalyst electrode inherits a honeycomb structure composed of 2D nanosheet arrays, unlike the smooth surface of NiCo-LDH nanosheets, NiCoMo LDH The nanosheets present a wrinkled rough surface. It can be seen from figures g, h, and i that the prepared F-NiCoMo LDH nanosheets exhibit a honeycomb structure composed of 2D ultrathin nanosheets when molybdate and ammonium fluoride are added simultaneously. In contrast, the surface roughness of F-NiCoMo LDH nanosheets is relatively moderate.

和

表明材料中应变晶格的存在。Figure 3 is the TEM images of LDH nanosheets prepared in Examples 1 and 2 and Comparative Example at different magnifications, wherein a, b, and c are respectively low-magnification TEM images of NiCo LDH, NiCoMo LDH and F-NiCoMo LDH, d, e and f are high-magnification TEM images of NiCo LDH, NiCoMo LDH and F-NiCoMo LDH, respectively. It can be seen from Figure 3 that the NiCo LDH nanosheets present a multilayer 2D nanostructure, and there is a certain degree of agglomeration among the nanosheets. When molybdate was added, the agglomeration phenomenon among the flexible NiCoMo LDH nanosheets weakened and the thickness decreased. When molybdate and ammonium fluoride were added simultaneously, the as-prepared F-NiCoMo LDH nanosheets showed highly dispersed ultrathin 2D nanosheets without agglomeration. High-magnification TEM images showing the measured average (221) lattice spacing in NiCo LDH, NiCoMo LDH and F-NiCoMoLDH crystals, respectively

and

Indicates the presence of a strained lattice in the material.

The self-supporting LDH electrocatalyst HER electrode prepared in Examples 1 and 2 and the catalyst electrode prepared in Comparative Example were directly used as working electrodes and tested in 1M KOH solution.

Fig. 4 is the LSV performance test curves of the self-supporting LDH electrocatalyst HER electrode prepared in Examples 1 and 2 and the catalyst electrode prepared in the comparative example, and compared with commercial PtC. At a current density of 10 mA cm ^-2 , F-NiCoMo LDH/NF exhibits attractive catalytic activity for basic HER with an overpotential of 107.5 mV, which is 94.1 mV smaller than that of NiCo LDH/NF and NiCoMo LDH/NF, respectively. and 54.0mV. HER electrocatalytic activity of F-NiCoMo LDH/NF electrocatalyst materials and NiCo LDH/NF and NiCoMo LDH/NF even at higher current densities of 50 mA cm ^-2 , 100 mA cm ^-2 and 200 mA cm ^-2 Compared with electrocatalyst materials, it also has obvious advantages, and its overpotentials are 192.5mV, 214.8mV and 226.2mV, respectively. Although the HER activity of F-NiCoMo LDH/NF is lower than that of PtC/NF (η = 35.5 mV) at 10 mA cm ^-2 , as the current density increases, the HER catalytic activity of F-NiCoMo LDH/NF gradually approaches that of PtC/NF, and surpassed PtC/NF at high current densities.

Fig. 5 is the stability test of the F-NiCoMo LDH/NF prepared in Example 1, which shows a constant current density of 40mA·cm ^-2 under the constant voltage it measurement curve test lasting 50 hours. Indicating the excellent stability of the material.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. It should be pointed out that those skilled in the art can make some improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims (10)

1. A method for preparing a self-supporting electrocatalytic hydrogen evolution catalyst electrode with a strained lattice, characterized in that it may further comprise the steps: Mix nickel salt, cobalt salt, molybdate, urea and water to obtain a mixed solution; The mixed solution is mixed with the nickel foam, and the hydrothermal reaction is carried out to obtain the self-supporting electrocatalytic hydrogen evolution catalyst electrode with the strained lattice. 2. The preparation method according to claim 1, characterized in that, the molar ratio of the nickel salt to the molybdate is (1-3):1. 3. The preparation method according to claim 1 or 2, characterized in that the molar ratio of the cobalt salt to the molybdate is (1-3):1. 4. The preparation method according to claim 1, characterized in that the molar ratio of the metal salt to urea is (1-10): 1, and the metal salt includes nickel salt, cobalt salt and molybdate. 5. The preparation method according to claim 1, characterized in that, the mixed solution also contains ammonium fluoride. 6. The preparation method according to claim 5, characterized in that the molar ratio of the metal salt to ammonium fluoride is (1-10):1, and the metal salt includes nickel salt, cobalt salt and molybdate. 7. The preparation method according to claim 1, characterized in that, the temperature of the hydrothermal reaction is 100-200° C., and the time is 4-24 hours. 8 . The preparation method according to claim 1 , characterized in that, the ratio of nickel foam to metal salt is 1 cm ² : 0.1-10 mmol, and the metal salt includes nickel salt, cobalt salt and molybdate. 9. The self-supporting electrocatalytic hydrogen evolution catalyst electrode with strained lattice prepared by the preparation method according to any one of claims 1 to 8. 10. The application of the self-supporting electrocatalytic hydrogen evolution catalyst electrode with strained lattice as claimed in claim 9 as an electrocatalytic hydrogen evolution catalyst electrode.

Images