阅读说明：本技术 一种碱性电解水析氧催化电极、制备方法及其应用 (Alkaline electrolytic water oxygen evolution catalytic electrode, preparation method and application thereof ) 是由 杨生春 李璐 王斌 于 2021-07-22 设计创作，主要内容包括：本发明公开了一种碱性电解水析氧催化电极、制备方法及其应用,包括：将泡沫镍浸没入含有铁盐与PVP的DMF溶液中,取出后烘干；将浸有DMF溶液的泡沫镍在空气中退火；将退火后的泡沫镍浸没入含有铁盐与铬盐的水溶液中,在加热条件下反应,取出冲洗后烘干,得到催化电极Fe(Cr)OOH/Fe-(3)O-(4)。本发明还公开了Fe(Cr)OOH/Fe-(3)O-(4)在电解水中作为析氧电极的应用。本发明电解水催化电极能够在大电流密度条件下保持高活性与稳定性,能够有效降低电解水制氢成本,可应用于工业电解水析氧电极。(The invention discloses an alkaline electrolytic water oxygen evolution catalytic electrode, a preparation method and application thereof, wherein the preparation method comprises the following steps: immersing foamed nickel into a DMF solution containing ferric salt and PVP, taking out and drying; annealing the foamed nickel soaked with the DMF solution in air; immersing the annealed foamed nickel into an aqueous solution containing ferric salt and chromium salt, reacting under a heating condition, taking out, washing and drying to obtain a catalytic electrode Fe (Cr) OOH/Fe 3 O 4 . The invention also discloses Fe (Cr) OOH/Fe 3 O 4 The oxygen-evolving electrode can be used in the electrolysis of water. The water electrolysis catalytic electrode can keep high activity and stability under the condition of high current density, and can effectively reduce the cost of hydrogen production by water electrolysisCan be applied to industrial electrolytic water oxygen evolution electrodes.)

1. A preparation method of an alkaline electrolysis water oxygen evolution catalytic electrode is characterized by comprising the following steps:

1) immersing foamed nickel into a DMF solution containing ferric salt and PVP, taking out and drying;

2) annealing the foamed nickel soaked with the DMF solution in air;

3) immersing the annealed foamed nickel into an aqueous solution containing ferric salt and chromium salt, reacting under a heating condition, taking out, washing and drying to obtain a catalytic electrode Fe (Cr) OOH/Fe₃O₄。

2. The method for preparing an alkaline electrolytic water oxygen evolution catalytic electrode according to claim 1, wherein in the step 1), the DMF solution containing the iron salt and PVP is prepared according to the following method:

mixing iron salt and polyvinylpyrrolidone, adding into a dimethylformamide solution, wherein the concentration of the iron salt-dimethylformamide solution is 0.6-0.8 mol L^-1The concentration of the polyvinylpyrrolidone-dimethylformamide solution is 20-25 g L^-1。

3. The method as claimed in claim 2, wherein the iron salt is ferric nitrate, ferric chloride or ferric acetate.

4. The method for preparing an alkaline electrolytic water oxygen evolution catalytic electrode according to claim 2, wherein in the step 2), the annealing temperature is 300-400 ℃ and the annealing time is 40-80 min.

5. The method as claimed in claim 1, wherein the chromium salt is chromium nitrate, chromium chloride or chromium acetate.

6. The method for preparing an alkaline electrolytic water oxygen evolution catalytic electrode according to claim 1, wherein the molar concentration of the iron salt and the chromium salt in the aqueous solution containing the iron salt and the chromium salt is 0.08-0.1 mol L^-1。

7. The method for preparing an alkaline electrolytic water oxygen evolution catalytic electrode according to claim 1, wherein in the step 3), the reaction heating temperature is 70-90 ℃ and the reaction time is 2-10 min.

8. An alkaline electrolytic water oxygen evolution catalytic electrode, characterized in that it is prepared according to the method of claims 1-6.

9. Use of a catalytic electrode prepared according to any one of claims 1 to 7 as an oxygen evolution electrode in electrolysis of water.

Technical Field

The invention relates to an electrolytic water catalytic electrode, in particular to an alkaline electrolytic water oxygen evolution catalytic electrode and a preparation method thereof.

Background

The electrolytic water is the most promising hydrogen production method, and can convert intermittent renewable energy into hydrogen energy, so that the electrolytic water has become a research hotspot in recent years. At present, the number of the current day,the cost of 1kg of hydrogen produced by alkaline electrolysis of water is about $ 4, which is much higher than that of hydrogen produced by methane steam reforming ($ 1.7), thus preventing the popularization and application of hydrogen production by electrolysis of water. The cost of hydrogen production by water electrolysis mainly comes from electric charge, and the over-potential of the cathode and the anode in the reaction process increases the energy consumption of hydrogen production and reduces the energy conversion efficiency. In the water electrolysis reaction, the anodic Oxygen Evolution Reaction (OER) is a 4-electron transfer process, the kinetics is slow, the overpotential is high, and the overpotential is the bottleneck of the water decomposition reaction. In addition, most of the electrolytic water catalysts reported in the current research are powdery catalysts, which easily fall off from the electrode surface during the violent reaction, thereby affecting the stability of the electrode. In order to aim at actual industrial production, the electrolytic water catalytic electrode needs to maintain high activity and stability under the condition of high current density, and particularly, an alkaline electrolytic cell needs to reach 500mA cm under the condition of overpotential not exceeding 300mV^-2。

Therefore, the development of the electrolytic water catalytic electrode with high activity and high stability is of great significance.

Disclosure of Invention

The invention aims to provide Fe (Cr) OOH/Fe for alkaline electrolysis of water to separate out oxygen₃O₄Composite catalytic electrode and preparation method thereof, and prepared Fe (Cr) OOH/Fe₃O₄The overpotential of the oxygen evolution reaction can be effectively reduced, and the stability and the activity are excellent, so that the hydrogen production cost of the electrolyzed water can be effectively reduced, and the popularization and the application of the technology are promoted.

The purpose of the invention is realized by the following technical scheme.

A preparation method of an alkaline electrolysis water oxygen evolution catalytic electrode comprises the following steps:

1) immersing foamed nickel into a DMF solution containing ferric salt and PVP, taking out and drying;

2) annealing the foamed nickel soaked with the DMF solution in air;

3) immersing the annealed foamed nickel into an aqueous solution containing ferric salt and chromium salt, reacting under a heating condition, taking out, washing and drying to obtain a catalytic electrode Fe (Cr) OOH/Fe₃O₄。

Preferably, in step 1), the DMF solution containing iron salt and PVP is prepared as follows:

mixing iron salt and polyvinylpyrrolidone, adding into a dimethylformamide solution, wherein the concentration of the iron salt-dimethylformamide solution is 0.6-0.8 mol L^-1The concentration of the polyvinylpyrrolidone-dimethylformamide solution is 20-25 g L^-1。

Preferably, the iron salt is ferric nitrate, ferric chloride or ferric acetate.

Preferably, in the step 2), the annealing temperature is 300-400 ℃ and the time is 40-80 min.

Preferably, the chromium salt is chromium nitrate, chromium chloride or chromium acetate.

Preferably, in the aqueous solution containing iron salt and chromium salt, the molar concentration of the iron salt and the chromium salt is 0.08-0.1 mol L^-1。

Preferably, in the step 3), the reaction heating temperature is 70-90 ℃, and the reaction time is 2-10 min.

The alkaline electrolyzed water oxygen evolution catalytic electrode prepared by the method can be applied as an oxygen evolution electrode in electrolyzed water.

The invention has the beneficial effects that:

fe (Cr) OOH/Fe prepared by the method₃O₄The composite catalytic electrode can effectively reduce the overpotential of oxygen evolution reaction and has excellent stability, thereby effectively reducing the cost of hydrogen production by water electrolysis and promoting the popularization and application of the technology.

The invention adopts foam Nickel (NF) as a substrate to prepare Fe (Cr) OOH/Fe₃O₄The surface of the composite catalytic electrode is rough and porous, so that the hydrophilicity of the electrode can be effectively improved, and the mass transfer of reactants is promoted; FeOOH and Fe₃O₄And Cr is introduced into FeOOH to form Fe (Cr) OOH, so that the OER reaction energy barrier of the catalytic electrode can be obviously reduced, and the charge transfer performance of the catalytic electrode is improved. The good material and charge transmission performance enables the electrode to have excellent catalytic activity.

Fe (Cr) OOH and Fe₃O₄Has good OER stability in alkaline solution, and can further improve the mechanical strength of the catalyst and the substrate material by the processes of dipping, annealing and the like, so that the prepared Fe (Cr) OOH/Fe can be prepared by reasonable component selection and preparation process design₃O₄The composite catalytic electrode has good stability.

According to the scheme, the foam nickel is immersed into the DMF solution containing the iron salt and the PVP, so that the loading capacity of the catalyst can be effectively improved, and the catalytic activity of the electrode is improved. The stability of the catalytic electrode can be effectively improved by annealing the foam nickel soaked with the DMF solution in the air. The annealed foamed nickel is immersed into an aqueous solution containing iron salt and chromium salt, and the reaction is carried out under the controlled heating condition to form Fe (Cr) OOH, so that the activity of the electrode is improved. The concentration of the iron salt-dimethylformamide solution and the concentration of the polyvinylpyrrolidone-dimethylformamide solution are adopted, so that the loading capacity of the catalyst can be effectively improved, and the catalytic activity of the electrode is improved. Specific iron salt and chromium salt are adopted and the molar concentration is controlled, so that Fe (Cr) OOH can be formed, and the activity of the electrode is improved.

The invention is applied as an oxygen evolution electrode in the electrolyzed water, and the experimental result shows that Fe (Cr) OOH/Fe₃O₄The composite catalytic electrode can effectively reduce the overpotential of oxygen evolution reaction and has excellent stability, thereby effectively reducing the cost of hydrogen production by water electrolysis and promoting the popularization and application of the technology.

Drawings

FIG. 1 is Fe (Cr) OOH/Fe prepared in example 1₃O₄Low power SEM images of the composite catalytic electrode;

FIG. 2 is Fe (Cr) OOH/Fe prepared in example 1₃O₄High power SEM images of the composite catalytic electrode;

FIG. 3 is Fe (Cr) OOH/Fe prepared in example 1₃O₄EDX energy spectra of the composite catalytic electrode;

FIG. 4 is Fe (Cr) OOH/Fe prepared in example 1, example 2, example 3, example 4 and example 5₃O₄Oxygen evolution by composite catalytic electrodePerformance plots of the reactions;

FIG. 5 is Fe (Cr) OOH/Fe prepared in example 1₃O₄The stability performance diagram of the composite catalytic electrode in oxygen evolution reaction.

Detailed Description

The invention will be further elucidated and described with reference to the embodiments and drawings of the specification:

the preparation method of the alkaline electrolysis water oxygen evolution catalytic electrode comprises the following steps:

in the technical scheme, the related raw materials are all sold in the market.

1) Immersing foamed nickel into a DMF solution containing ferric salt and PVP, taking out and drying; the DMF solution containing iron salt and PVP was prepared as follows:

mixing iron salt and polyvinylpyrrolidone, adding into a dimethylformamide solution, wherein the concentration of the iron salt-dimethylformamide solution is 0.6-0.8 mol L^-1The concentration of the polyvinylpyrrolidone-dimethylformamide solution is 20-25 g L^-1. The iron salt is ferric nitrate, ferric chloride or ferric acetate.

2) And (3) annealing the foamed nickel soaked with the DMF solution in the air at the temperature of 300-400 ℃ for 40-80 min.

3) Immersing the annealed foamed nickel into L with the molar concentration of 0.08-0.1 mol^-1Reacting in an aqueous solution containing ferric salt and chromium salt at the heating temperature of 70-90 ℃ for 2-10 min, taking out, washing and drying to obtain a catalytic electrode Fe (Cr) OOH/Fe₃O₄。

The ferric salt is ferric nitrate, ferric chloride or ferric acetate; the chromium salt is chromium nitrate, chromium chloride or chromium acetate.

The present invention will be further described with reference to the following examples.

Example 1

1) 30mmol of ferric nitrate and 1g of PVP were added to 50mL of DMF, stirred at 60 ℃ for 20min, and 2X 3cm²The foamed nickel is immersed into the solution, taken out and dried.

2) Annealing the sample obtained in the step 1) at 300 ℃ for 80 min.

3) Adding 4mmol of ferric chloride and 4mmol of chromium nitrate into 50mL of water, keeping the solution at 80 ℃, stirring for 20min, immersing the sample obtained in the step 2) into the solution for reaction for 5min, taking out, washing and drying to obtain a final product Fe (Cr) OOH/Fe₃O₄。

FIG. 1 is the Fe (Cr) OOH/Fe prepared in example 1₃O₄Scanning electron microscope image of composite catalytic electrode, which shows that the sample retains the three-dimensional skeleton structure of foam nickel, and FIG. 2 shows Fe (Cr) OOH/Fe prepared in example 1₃O₄High power scanning electron microscope image of the composite catalytic electrode, from which Fe (Cr) OOH/Fe is seen₃O₄The composite catalytic electrode has a rough and porous surface appearance, so that the hydrophilicity and the electrochemical active area of the electrode can be effectively improved. FIG. 3 is the Fe (Cr) OOH/Fe prepared in example 1₃O₄The EDX energy spectrogram of the composite catalytic electrode shows that Fe, Cr and O elements exist in the catalytic electrode, and the catalytic electrode is successfully prepared.

Example 2

1) 40mmol of iron acetate and 1.25g of PVP were added to 50mL of DMF, stirred at 70 ℃ for 30min, and 2X 3cm²The foamed nickel is immersed into the solution, taken out and dried.

2) Annealing the sample obtained in the step 1) at 400 ℃ for 40 min.

3) Adding 5mmol ferric nitrate and 5mmol chromium chloride into 50mL water, keeping the solution at 70 ℃, stirring for 20min, immersing the sample obtained in the step 2) into the solution for reaction for 10min, taking out, washing and drying to obtain a final product Fe (Cr) OOH/Fe₃O₄。

Example 3

1) 35mmol of ferric chloride and 1.17g of PVP were added to 50mL of DMF, stirred at 80 ℃ for 40min, and 2X 3cm²The foamed nickel is immersed into the solution, taken out and dried.

2) Annealing the sample obtained in the step 1) at 350 ℃ for 50 min.

3) Adding 4.5mmol of iron acetate and 4.5mmol of chromium acetate into 50mL of water, keeping the solution at 75 ℃ and stirring for 20min, immersing the sample obtained in step 2)Reacting in the solution for 5min, taking out, washing and drying to obtain the final product Fe (Cr) OOH/Fe₃O₄。

Example 4

1) 36mmol of ferric nitrate and 1.20g of PVP were added to 50mL of DMF, stirred at 80 ℃ for 20min, and 2X 3cm²The foamed nickel is immersed into the solution, taken out and dried.

2) Annealing the sample obtained in the step 1) at 300 ℃ for 60 min.

3) Adding 4.7mmol of ferric nitrate and 4.7mmol of chromium chloride into 50mL of water, keeping the solution at 80 ℃, stirring for 20min, immersing the sample obtained in the step 2) into the solution for reaction for 2min, taking out, washing and drying to obtain a final product Fe (Cr) OOH/Fe₃O₄。

Example 5

1) Adding 40mmol ferric chloride and 1g PVP into 50mL DMF, stirring at 60 deg.C for 40min, and mixing 2 × 3cm²The foamed nickel is immersed into the solution, taken out and dried.

2) Annealing the sample obtained in the step 1) at 400 ℃ for 70 min.

3) Adding 5mmol of ferric chloride and 4mmol of chromium nitrate into 50mL of water, keeping the solution at 90 ℃, stirring for 20min, immersing the sample obtained in the step 2) into the solution for reaction for 10min, taking out, washing and drying to obtain a final product Fe (Cr) OOH/Fe₃O₄。

Fe (Cr) OOH/Fe prepared in example 1, example 2, example 3, example 4 and example 5₃O₄The composite catalytic electrode is used as a working electrode, a saturated calomel electrode is used as a reference electrode, a carbon rod is used as a counter electrode, and electrochemical performance test is carried out in a 1M KOH solution by using a Chenghua 760D electrochemical workstation. The linear scan profile of the oxygen evolution reaction is shown in figure 4. Fe (Cr) OOH/Fe prepared in example 1, example 2, example 3, example 4 and example 5₃O₄Composite catalytic electrode 500mA cm^-2The oxygen evolution overpotential at the current density is 251, 265, 272, 275 and 244mV respectively, which can meet the requirement of 500mA cm of alkaline electrolytic tank^-2The overpotential at the current density does not exceed 300mVThe results show that the catalyst has good catalytic activity. Fe (Cr) OOH/Fe obtained in example 1₃O₄The oxygen evolution stability test results of the composite catalytic electrode are shown in FIG. 5, which is capable of measuring at 100mA cm^-2The stable operation is carried out for 100h at the current density, and the performance is not obviously attenuated, which indicates that Fe (Cr) OOH/Fe₃O₄The composite catalytic electrode has good catalytic stability.

Thus, the Fe (Cr) OOH/Fe prepared by the above method₃O₄The composite catalytic electrode can be applied to industrial electrolytic water oxygen evolution electrodes.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.