CN111905744A - Nickel-iron hydroxide composite material, catalyst, preparation method and application - Google Patents

Abstract

The invention discloses a nickel-iron hydroxide composite material, a catalyst, a preparation method and application, wherein pretreated foamed nickel is added into an iron nitrate solution or an iron chloride solution according to a nickel-iron molar ratio of 1: 1-10, and ultrasonic treatment is carried out to obtain a nickel-iron mixed solution after the foamed nickel is fully dissolved; putting the nickel-iron mixed solution into an electrolytic cell, using carbon cloth as a working electrode, and depositing a nickel-iron hydroxide composite material on the carbon cloth by using a cathode deposition method; washing and naturally airing the deposited carbon cloth to obtain the nickel-iron hydroxide composite material catalyst; the preparation process of the nickel-iron hydroxide composite catalyst is simple, the prepared nickel-iron hydroxide composite catalyst has excellent catalytic performance when being applied to the electrocatalytic oxygen production reaction, the oxygen evolution reaction rate of the nickel-iron hydroxide composite catalyst is far superior to that of a nickel-iron-based electrocatalytic material prepared by a traditional solution method, the electrocatalytic oxygen evolution stability is good, and the nickel-iron hydroxide composite catalyst has good industrial application prospect.

Description

A kind of nickel-iron hydroxide composite material, catalyst, preparation method and application

technical field

The invention relates to the technical field of electrocatalytic material preparation, in particular to a nickel-iron hydroxide composite material, a catalyst, a preparation method and an application.

Background technique

Environmental pollution and energy crisis have prompted people to look for a new clean energy to replace fossil energy. Hydrogen energy, as a renewable clean energy with high energy density, has been favored by people.

Electrocatalytic water splitting is a common technology for hydrogen production. However, the rate of hydrogen evolution reaction (HER) from water electrolysis is limited by the oxygen evolution reaction (OER). Therefore, improving the efficiency of electrocatalysts for the oxygen evolution reaction is the key to improving hydrogen production from water electrolysis.

At present, the catalysts with high performance oxygen evolution reaction have been reported, including ruthenium dioxide (RuO ₂ ) and iron, cobalt, manganese, nickel-based nanomaterials, etc., but these catalysts have poor electrocatalytic oxygen evolution performance and cannot meet industrial applications. requirements.

In view of the above-mentioned defects, the creator of the present invention finally obtained the present invention after a long period of research and practice.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned technical defects, the technical solution adopted in the present invention is to provide a preparation method of a nickel-iron hydroxide composite material catalyst, comprising the steps of:

S1, according to the molar ratio of nickel and iron of 1:1～10, add pretreated nickel foam to the ferric nitrate solution or the ferric chloride solution, ultrasonically, and after fully dissolving, obtain a nickel-iron mixed solution;

S2, putting the nickel-iron mixed solution into an electrolytic cell, using carbon cloth as a working electrode, and using a cathode deposition method to deposit a nickel-iron hydroxide composite material on the carbon cloth;

S3, the deposited carbon cloth is washed and air-dried to obtain a nickel-iron hydroxide composite catalyst.

Preferably, in the step S1, the pretreatment of the nickel foam is acid washing, water washing and ethanol washing.

Preferably, in the step S2, the cathode deposition process is carried out on a CHI660E electrochemical workstation, in a three-electrode system, the carbon cloth is used as the working electrode, the carbon rod is used as the counter electrode, and the saturated calomel electrode is used as the reference electrode. .

Preferably, in the step S2, the deposition temperature is performed at room temperature, the electrodeposition current density is 20 mA/cm ² , and the deposition time is 10 min.

Preferably, a nickel-iron hydroxide composite material is prepared through steps S1 and S2 in the preparation method of the nickel-iron hydroxide composite catalyst.

Preferably, a nickel-iron hydroxide composite catalyst is prepared by the preparation method of the nickel-iron hydroxide composite catalyst, comprising a carbon cloth substrate and a nickel-iron hydroxide deposited on the carbon cloth substrate. Composite catalytic layer.

Preferably, the application of a nickel-iron hydroxide composite material in the water desorption oxygen reaction.

Preferably, the application of a nickel-iron hydroxide composite catalyst in the reaction of moisture desorption oxygen.

Compared with the prior art, the beneficial effects of the present invention are: the preparation process of the nickel-iron hydroxide composite material catalyst of the present invention is simple, and the prepared nickel-iron hydroxide composite material catalyst is applied to the electrocatalytic oxygen production reaction (OER) It has excellent catalytic performance, its oxygen evolution reaction rate is much better than that of nickel-iron-based electrocatalytic materials prepared by traditional solution method, and the electrocatalytic oxygen evolution stability is good, and it has a good industrial application prospect.

Description of drawings

Fig. 1 is the SEM image of the nickel-iron hydroxide composite material prepared in Example 1;

Fig. 2 is the SEM image of the nickel-iron hydroxide composite material prepared by embodiment ten;

Fig. 3 is the SEM image of the nickel-iron hydroxide composite material prepared in Example 11;

Fig. 4 is the electrocatalytic oxygen production linear sweep voltammogram of the nickel-iron hydroxide composite catalyst prepared in Examples 1-8 and Example 10;

5 is a linear sweep voltammogram of electrocatalytic oxygen production of the nickel-iron hydroxide composite catalysts prepared in Examples 1, 3, 8 and Examples 12 to 14;

Fig. 6 is the electrocatalytic oxygen generation linear sweep voltammogram of the nickel-iron hydroxide composite catalyst prepared in Example 1 and Examples 9-12;

Fig. 7 is the statistical graph of overpotential under different current densities of embodiment one, ten and twelve;

Fig. 8 is the Tafel curve diagram of 2*1NF-Fe, 3*1NF-Fe, 4*1NF-Fe, 5*1NF-Fe, 8*1NF-Fe and Fe;

Fig. 9 is the electrochemical impedance spectra of 3*1NF-Fe, 4*1NF-Fe and 5*1NF-Fe;

Figure 10 is a graph of the stability test results of 4*1NF-Fe.

Detailed ways

The above and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

The preparation method of the nickel-iron hydroxide composite material catalyst of the present invention comprises the following steps:

S1, according to the molar ratio of nickel and iron of 1:1～10, add pretreated nickel foam to the ferric nitrate solution, ultrasonically, after fully dissolving, obtain a nickel-iron mixed solution;

S2, put the nickel-iron mixed solution into the electrolytic cell, use the carbon cloth as the working electrode, and use the cathode deposition method to deposit the nickel-iron hydroxide composite material on the carbon cloth;

S3, the deposited carbon cloth is washed and air-dried to obtain a nickel-iron hydroxide composite catalyst.

In the step S1, ferric nitrate can be replaced with ferric chloride.

In the step S1, the pretreatment of nickel foam is through acid washing, water washing and ethanol washing.

In the step S2, the cathode deposition process is carried out on a CHI660E electrochemical workstation. Under the three-electrode system, the carbon cloth is used as the working electrode, the carbon rod is used as the counter electrode, and the saturated calomel electrode is used as the reference electrode.

In the step S2, the deposition temperature is performed at room temperature, the electrodeposition current density is 20 mA/cm ² , and the deposition time is 10 min.

The nickel-iron hydroxide composite material catalyst obtained by the preparation method of the nickel-iron hydroxide composite material catalyst of the present invention comprises a carbon cloth substrate and a nickel-iron hydroxide composite material catalyst layer deposited and formed on the carbon cloth substrate.

For the preparation method of the nickel-iron hydroxide composite catalyst of the present invention, the nickel-iron hydroxide composite catalyst supported on carbon cloth can be prepared by dissolving foamed nickel in a ferric nitrate solution and using a cathode deposition method.

The prepared nickel ^- iron hydroxide composite catalyst has excellent catalytic performance when applied to electrochemical oxygen evolution reaction (OER). Phil's slope is 46mV/dec. When a current of 20 mA/cm ² is applied to the nickel-iron hydroxide composite catalyst prepared by the method of the present invention, its electrocatalytic oxygen evolution performance remains stable, so the nickel-iron hydroxide composite catalyst of the present invention is suitable for industrial application.

Example 1

In this embodiment, a preparation method of a nickel-iron hydroxide composite catalyst is provided, comprising the following steps:

S1, add the pretreated 4*1cm nickel foam into 50ml of 0.1M ferric nitrate solution, ultrasonicate for 30min, and after the foam nickel is fully dissolved, obtain a nickel-iron mixed solution with a nickel-iron molar ratio of 1:2.

S2, take 25ml of nickel-iron mixed solution and put it into the electrolytic cell, use carbon cloth as the working electrode, carbon rod as the counter electrode, and saturated calomel electrode as the reference electrode. The nickel-iron hydroxide composite material was deposited on the carbon cloth by the cathodic deposition method, the electrodeposition current density was 20 mA/cm ² , and the deposition time was 10 min.

S3, the deposited carbon cloth is washed and air-dried to obtain a nickel-iron hydroxide composite material catalyst, whose nickel-iron ratio is 1:2, and is denoted as 4*1NF-Fe.

The prepared nickel-iron hydroxide composite material catalyst, including a carbon cloth substrate and a catalytic layer, has both the function of a catalyst and the function of an electrode, is convenient to use, is used for electrolyzing water to produce oxygen, and can simplify its technological process.

The SEM image of the nickel-iron hydroxide composite material prepared in step S3 of this example is shown in FIG. 1 .

A current of 20 mA/cm ² was applied to 4*1NF-Fe for 24 h to test the stability of 4*1NF-Fe. The results are shown in Figure 10. It can be seen from the results in Fig. 10 that the electrocatalytic oxygen evolution performance of 4*1NF-Fe remains stable after applying a current of 20 mA/cm ² for 24 h, which is suitable for industrial application.

Embodiment 2

In this example, 1*1cm of foamed nickel is used to replace the 4*1cm of foamed nickel in step S1 of Example 1 to prepare a nickel-iron hydroxide composite material catalyst, whose nickel-iron ratio is 1:10, denoted as 1* 1NF-Fe.

Other implementations are as in Example 1.

Embodiment 3

In this example, 2*1cm of foamed nickel is used to replace the 4*1cm of foamed nickel in step S1 of Example 1 to prepare a nickel-iron hydroxide composite catalyst, and the nickel-iron ratio is 1:4, denoted as 2* 1NF-Fe.

Other implementations are as in Example 1.

Embodiment 4

In this example, 3*1cm foamed nickel is used to replace the 4*1cm foamed nickel in step S1 of Example 1 to prepare a nickel-iron hydroxide composite catalyst, and the nickel-iron ratio is 1:2.5, denoted as 3* 1NF-Fe.

Other implementations are as in Example 1.

Embodiment 5

In this example, 5*1cm nickel foam is used to replace the 4*1cm nickel foam in step S1 of Example 1 to prepare a nickel-iron hydroxide composite material catalyst, and the nickel-iron ratio is 1:1.5, denoted as 5* 1NF-Fe.

Other implementations are as in Example 1.

Embodiment 6

In this example, 6*1cm of foamed nickel is used to replace the 4*1cm of foamed nickel in step S1 of Example 1 to prepare a nickel-iron hydroxide composite catalyst, which is denoted as 6*1NF-Fe.

Other implementations are as in Example 1.

Embodiment 7

In this example, 7*1cm of foamed nickel is used to replace the 4*1cm of foamed nickel in step S1 of Example 1 to prepare a nickel-iron hydroxide composite catalyst, which is denoted as 7*1NF-Fe.

Other implementations are as in Example 1.

Embodiment 8

In this example, 8*1cm nickel foam is used to replace the 4*1cm nickel foam in step S1 of Example 1, to prepare a nickel-iron hydroxide composite catalyst, whose nickel-iron ratio is 1:1, denoted as 8* 1NF-Fe.

Other implementations are as in Example 1.

On the electrochemical workstation, the three-electrode system was used to test the electrocatalytic water splitting and oxygen production performance of the nickel-iron hydroxide composite catalysts prepared in Examples 1-8. The specific process is as follows: 1*1NF-Fe, 2*1NF -Fe, 3*1NF-Fe, 4*1NF-Fe, 5*1NF-Fe, 6*1NF-Fe, 7*1NF-Fe, 8*1NF-Fe are working electrodes, and platinum sheet electrodes are used as counter electrodes. Using Hg/HgO electrode as the reference electrode and 1 mol/L potassium hydroxide solution as the electrolyte, the electrocatalytic oxygen generation linear sweep voltammetry of the nickel-iron hydroxide composite catalyst prepared from the nickel-iron mixed solution of different molar ratios was tested. curve, and its electrocatalytic oxygen production linear sweep voltammetry curve is shown in Figure 4.

It can be seen from the results in Figure 4 that 5*1NF-Fe and 8*1NF-Fe have oxidation peaks due to the high content of nickel, so their linear scan voltammetry curves cannot be used as a criterion for judging whether the oxygen evolution performance is excellent or not. However, no oxidation peaks appeared in 4*1NF-Fe, 3*1NF-Fe, 2*1NF-Fe and Fe. Therefore, under the same current density, the samples of 4*1NF-Fe with a nickel-iron ratio of 1:2 It has a smaller overpotential, so the electrocatalytic oxygen evolution performance of the nickel-iron hydroxide composite catalyst prepared by the 4*1cm nickel foam is better.

Embodiment 9

In this example, 50ml of 0.1M ferric chloride solution was used to replace 50ml of 0.1M ferric nitrate solution in step S1 of Example 1 to prepare a nickel-iron hydroxide composite material catalyst, which is denoted as ₄ *1NF-FeCl3.

Other implementations are as in Example 1.

Embodiment ten

S1, configure 50ml of 0.1M ferric nitrate solution, put 25ml of ferric nitrate solution into the electrolytic cell, use carbon cloth as working electrode, carbon rod as counter electrode, saturated calomel electrode as reference electrode. Iron hydroxide was deposited on the carbon cloth by cathodic deposition, the electrodeposition current density was 20 mA/cm ² , and the deposition time was 10 min.

S2, the deposited carbon cloth is washed and air-dried to obtain an iron hydroxide catalyst, which is denoted as Fe.

The SEM image of the iron hydroxide prepared in step S2 of this example is shown in FIG. 2 .

It can be seen from Figure 2 that the Fe catalyst is a radial flower-like nanosheet.

Embodiment 11

S1, configure 50ml of 0.1M nickel nitrate solution, put 25ml of nickel nitrate solution into the electrolytic cell, use carbon cloth as working electrode, carbon rod as counter electrode, saturated calomel electrode as reference electrode. Nickel hydroxide was deposited on the carbon cloth by cathodic deposition, the electrodeposition current density was 20 mA/cm ² , and the deposition time was 10 min.

S2, the deposited carbon cloth is washed and air-dried to obtain a nickel hydroxide catalyst, which is denoted as Ni.

The SEM image of the nickel hydroxide prepared in step S2 of this example is shown in FIG. 3 . It can be seen from Figure 3 that the Ni catalyst is agglomerated nanosheets.

Embodiment 12

S1, adding nickel nitrate to 50ml of 0.1M ferric nitrate solution, so that the concentration of nickel nitrate is 0.2M, that is, the molar ratio of nickel and iron is 1:2, and the mixture is uniform.

S2, take 25ml of the mixed solution and put it into the electrolytic cell, use carbon cloth as the working electrode, carbon rod as the counter electrode, and saturated calomel electrode as the reference electrode. The nickel-iron hydroxide composite material was deposited on the carbon cloth by the cathodic deposition method, the electrodeposition current density was 20 mA/cm ² , and the deposition time was 10 min.

S3, the deposited carbon cloth is washed and air-dried to obtain a nickel-iron hydroxide composite catalyst, which is denoted as Ni ₁ Fe ₂ .

Embodiment thirteen

In this example, 0.4M nickel nitrate was used to replace the 0.2M nickel nitrate in step S1 of Example 12 to prepare a nickel-iron hydroxide composite material catalyst, which is denoted as Ni ₁ Fe ₄ .

Other implementations are as in Example 12.

Embodiment 14

In this example, 0.1M nickel nitrate was used to replace the 0.2M nickel nitrate in step S1 of Example 12 to prepare a nickel-iron hydroxide composite catalyst, which is denoted as Ni ₁ Fe ₁ .

Other implementations are as in Example 12.

On the electrochemical workstation, the three-electrode system was used to test the electrocatalytic water decomposition and oxygen production performance of the nickel-iron hydroxide composite catalysts prepared in Examples 9 to 14. The specific process is as follows: Ni ₁ Fe ₁ and Ni ₁ Fe _2. Ni ₁ Fe ₄ is used as the working electrode, the platinum sheet electrode is used as the counter electrode, the Hg/HgO electrode is used as the reference electrode, and the 1mol/L potassium hydroxide solution is used as the electrolyte to test the preparation of nickel-iron mixed solutions with different molar ratios The electrocatalytic oxygen production linear sweep voltammetry curve of the nickel-iron hydroxide composite catalyst is shown in Figure 5.

It can be seen from the results in Figure 5 that under the same molar ratio of nickel to iron, the oxygen evolution performance of the nickel-iron hydroxide composite catalyst prepared by using foamed nickel as the nickel source is better than that of the nickel-iron hydride prepared by using nickel nitrate as the nickel source. Oxide composite catalyst.

Using 4*1NF-FeCl ₃ , Ni and Fe as working electrodes, platinum sheet electrode as counter electrode, Hg/HgO electrode as reference electrode, and 1mol/L potassium hydroxide solution as electrolyte, different molar ratios were tested. The electrocatalytic oxygen production linear sweep voltammetry curve of the nickel-iron hydroxide composite catalyst prepared from the nickel-iron mixed solution is shown in Figure 6.

From the results in Figure 6, it can be seen that the electrocatalytic oxygen evolution performance of 4*1NF-Fe and 4*1NF-FeCl ₃ is excellent, and in the case of the same molar ratio of nickel to iron, nickel-iron-hydrogen prepared from foamed nickel as nickel source The oxygen evolution performance of the oxide composite catalysts is far better than that of the nickel-iron hydroxide composite catalysts prepared from nickel nitrate as the nickel source and the pure nickel and pure iron hydroxide catalysts.

Embodiment fifteen

In this example, the Tafel curves of 2*1NF-Fe, 3*1NF-Fe, 4*1NF-Fe, 5*1NF-Fe, 8*1NF-Fe, Ni ₁ Fe ₂ and Fe under different current densities were tested. potential to compare the electrocatalytic ability of 4*1NF-Fe, Ni ₁ Fe ₂ and Fe to split water to produce oxygen. The specific process is as follows:

Using 4*1NF-Fe as the working electrode, the platinum sheet electrode as the counter electrode, the Hg/HgO electrode as the reference electrode, and the 1mol/L potassium hydroxide solution as the electrolyte, the current density was set as 10mA/cm ² , 20mA/cm ² , 50mA/cm ² , the overpotentials of 4*1NF-Fe under different current densities were tested, and the statistical graphs of overpotentials under different current densities are shown in Figure 7 .

Taking Ni1Fe2 as the working electrode, the platinum sheet electrode as the counter electrode, the Hg/HgO electrode as the reference electrode, and the 1mol/L potassium hydroxide solution as the electrolyte, the current densities are set to 10mA/cm ² and 20mA/cm ² respectively. , 50mA/cm ² , test the overpotential of Ni ₁ Fe ₂ under different current densities, and the statistical graph of overpotential under different current densities is shown in Figure 7 .

Taking Fe as the working electrode, the platinum sheet electrode as the counter electrode, the Hg/HgO electrode as the reference electrode, and the 1mol/L potassium hydroxide solution as the electrolyte, the current densities were set as 10mA/cm ² and 20mA/cm ² respectively. , 50 mA/cm ² , the overpotential of Fe under different current densities was tested, and the statistical graph of overpotential under different current densities is shown in Figure 7 .

Figure 8 is the Tafel curve of 2*1NF-Fe, 3*1NF-Fe, 4*1NF-Fe, 5*1NF-Fe, 8*1NF-Fe and Fe.

Figure 9 is the electrochemical impedance spectrum of 3*1NF-Fe, 4*1NF-Fe and 5*1NF-Fe.

It can be seen from the results in Fig. 7 that when the current densities are 10mA/cm ² , 20mA/cm ² and 50mA/cm ² , the overpotentials corresponding to 4*1NF-Fe are 198mV, 22mV1 and 238mV, respectively, and the corresponding overpotentials of Ni ₁ Fe ₂ are 198mV, 22mV and 238mV respectively. The overpotentials are 274mV, 286mV, and 301mV, respectively, and the overpotentials corresponding to Fe are 429mV, 44mV6, and 465mV, respectively. The lower the overpotential, the faster the reaction speed, the less energy consumption, and the better the oxygen evolution performance. The oxygen evolution performance of the nickel-iron hydroxide composite catalyst prepared as a nickel source is far superior to that of the nickel-iron hydroxide composite catalyst prepared from nickel nitrate as a nickel source.

It can be seen from the results in Figure 8 that the Tafel slope of 4*1NF-Fe is 46mV/dec. The Tafel slope represents the difficulty of the electrochemical reaction. The smaller the slope, the easier the electrochemical reaction occurs. Therefore, the nickel foam is used as the nickel source. The prepared nickel-iron hydroxide composite catalyst has excellent oxygen evolution performance.

From the results in Fig. 9, it can be seen that 4*1NF-Fe has the smallest radius and the smallest charge transfer resistance. Therefore, 4*1NF-Fe is a nickel-iron hydroxide composite catalyst with a molar ratio of 1:2. The ratio of 3*1NF-Fe and 5*1NF-Fe has better electrical conductivity and better oxygen evolution performance.

The above descriptions are only preferred embodiments of the present invention, which are merely illustrative rather than limiting for the present invention. Those skilled in the art understand that many changes, modifications and even equivalents can be made within the spirit and scope defined by the claims of the present invention, but all fall within the protection scope of the present invention.

Claims (8)

1. A preparation method of a nickel-iron hydroxide composite material catalyst is characterized by comprising the following steps:

s1, according to 1: 1-10 mol ratio of nickel and iron, adding pretreated foamed nickel into an iron nitrate solution or an iron chloride solution, performing ultrasonic treatment, and fully dissolving to obtain a nickel and iron mixed solution;

s2, putting the nickel-iron mixed solution into an electrolytic cell, using carbon cloth as a working electrode, and depositing a nickel-iron hydroxide composite material on the carbon cloth by using a cathode deposition method;

and S3, washing and naturally airing the deposited carbon cloth to obtain the nickel-iron hydroxide composite catalyst.

2. The method for preparing a nickel iron hydroxide composite catalyst according to claim 1, wherein in the step S1, the pretreatment of the foamed nickel is acid washing, water washing and ethanol washing.

3. The method for preparing a nickel iron hydroxide composite catalyst according to claim 1, wherein in the step S2, the cathode deposition process is performed on a CHI660E electrochemical workstation, under a three-electrode system, a carbon cloth is used as a working electrode, a carbon rod is used as a counter electrode, and a saturated calomel electrode is used as a reference electrode.

4. The method for preparing a nickel iron hydroxide composite catalyst according to claim 1, wherein in the step S2, the deposition temperature is performed at room temperature and the electrodeposition current density is 20mA/cm²The deposition time was 10 min.

5. A nickel iron hydroxide composite material characterized by being produced by steps S1, S2 in the method for producing a nickel iron hydroxide composite material catalyst according to any one of claims 1 to 4.

6. A nickel-iron hydroxide composite catalyst, which is prepared by the preparation method of the nickel-iron hydroxide composite catalyst according to any one of claims 1 to 4, and comprises a carbon cloth substrate and a nickel-iron hydroxide composite catalyst layer deposited and formed on the carbon cloth substrate.

7. Use of the nickel iron hydroxide composite material according to claim 5 in a water-splitting oxygen analysis reaction.

8. Use of the nickel iron hydroxide composite catalyst according to claim 6 in water decomposition oxygen analysis reactions.

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