阅读说明：本技术 一种常温常压下纳米片修饰电极及其制备工艺 (Nanosheet modified electrode at normal temperature and normal pressure and preparation process thereof ) 是由 周清稳 郭艳玲 许程源 顾伟诗 潘忠芹 叶长青 姜启玉 于 2021-01-20 设计创作，主要内容包括：本发明公开了一种常温常压下纳米片修饰电极及其制备工艺,属于电催化剂材料技术领域。先对金属镍铁基底进行常温常压下酸浸泡清洁处理,得到新鲜金属镍铁基底；然后对得到的新鲜金属镍铁基底进行常温常压下去离子水浸泡处理,即可得到表面生长有镍铁组合氧化态纳米片物质的电极。本发明的纳米片修饰电极可用于提高电解水阳极析氧反应的性能,进而降低电解制氢的电解电压,降低能耗。(The invention discloses a nanosheet modified electrode at normal temperature and normal pressure and a preparation process thereof, and belongs to the technical field of electrocatalyst materials. Firstly, carrying out acid soaking and cleaning treatment on the metal nickel-iron substrate at normal temperature and normal pressure to obtain a fresh metal nickel-iron substrate; and then, carrying out deionized water soaking treatment on the obtained fresh metal nickel-iron substrate at normal temperature and normal pressure to obtain the electrode with the surface growing with the nickel-iron combined oxidation state nano sheet substance. The nanosheet modified electrode can be used for improving the performance of the anodic oxygen evolution reaction of the electrolyzed water, so that the electrolysis voltage of hydrogen production by electrolysis is reduced, and the energy consumption is reduced.)

1. A nanosheet modified electrode, comprising: the nano-sheet electrode is a metal nickel-iron electrode with a nickel-iron combined oxidation state nano-sheet substance growing on the surface.

2. The electrode of claim 1, wherein: the nickel-iron combined oxidation state nanosheet substance comprises one or more of nickel hydroxide, ferric hydroxide and ferrous hydroxide, and also comprises one or more of iron-doped nickel hydroxide, nickel-doped ferric hydroxide and nickel-doped ferrous hydroxide.

3. A process for preparing a nanosheet-modified electrode of claim 1, wherein the process comprises: the method comprises the following steps:

1) acid soaking and cleaning the metal nickel-iron substrate at normal temperature and normal pressure to obtain a fresh metal nickel-iron substrate;

2) and (3) soaking the obtained fresh metal nickel-iron substrate in deionized water at normal temperature and normal pressure to obtain the electrode with the surface growing with the nickel-iron combined oxidation state nano sheet substance.

4. The process according to claim 3, characterized in that: specifically, the step 1) is that the metal nickel-iron substrate is placed in an acetone solution for ultrasonic cleaning for 10-30 minutes at normal temperature and normal pressure, and then repeatedly cleaned by ethanol to remove a metal surface grease layer; and then placing the metal substrate in an acid solution with the concentration of 1-9 mol per liter for carrying out surface oxidation layer corrosion treatment for 30-120 minutes, finally washing the metal substrate with distilled water, and removing the metal surface oxidation layer to obtain the fresh metal ferronickel substrate.

5. The process according to claim 3, characterized in that: the metal ferronickel substrate adopts one of a ferronickel net, foam ferronickel or a ferronickel sheet.

6. The process according to claim 3, characterized in that: in the acid solution, the acid is one or more of hydrochloric acid, nitric acid, sulfuric acid, acetic acid and oxalic acid, and the total concentration of acid radical ions in the acid solution is 0.1-9 mol per liter; the acid solution also contains one or more of reducing agents of hydrazine, hydroxylamine, sodium borohydride, potassium borohydride and lithium aluminum hydride.

7. The process according to claim 3, characterized in that: specifically, the step 2) is to place a fresh metal nickel-iron substrate into deionized water at normal temperature and normal pressure, soak the fresh metal nickel-iron substrate for 12-72 hours, and naturally dry the fresh metal nickel-iron substrate in air to obtain the electrode with the surface growing with the nickel-iron combined oxidation state nano sheet substance.

Technical Field

The invention belongs to the technical field of electrocatalyst materials, and particularly relates to a nanosheet modified electrode at normal temperature and normal pressure and a preparation process thereof.

Background

The hydrogen energy is a green energy with great potential in the future, and the attention on the hydrogen energy is particularly obvious recently. The alkaline water electrolysis hydrogen production is one of important ways for obtaining hydrogen energy, and has the advantages of no pollution emission, high hydrogen production purity, simple process and the like compared with the hydrogen production by fossil energy. The electrolysis of water is a key reaction for realizing new energy storage and conversion technology. To meet practical requirements, an ideal water electrolysis catalyst should be efficient, cost effective, capable of achieving reasonably high current densities at relatively low overpotentials, and capable of stable operation over long periods of time.

At present, the anode mainly used for commercial alkaline water electrolysis is a pure nickel material, such as a nickel net, a nickel plate and the like. The electrode has the greatest advantage of long-term operation in alkaline environment, but has the fundamental defects that: 1) the intrinsic catalytic performance of the metallic nickel material is low; 2) the electrochemical area of the surface of the pure nickel material is small, the provided electrocatalytic activity area is low, and the full occurrence of catalytic reaction is restricted. Therefore, around the existing problems, it is of far-reaching significance to develop a new anode electrode with high efficiency, low cost and high catalytic activity.

Disclosure of Invention

The invention aims to solve the technical problem of providing a nanosheet modified electrode at normal temperature and normal pressure and a preparation process thereof, which are used for improving the performance of the anodic oxygen evolution reaction of electrolyzed water, further reducing the electrolysis voltage of hydrogen production by electrolysis and reducing the energy consumption.

In order to solve the technical problem, the invention provides a nanosheet modified electrode at normal temperature and normal pressure, wherein the electrode is a metal nickel-iron electrode with a nickel-iron combined oxidation state nanosheet substance growing on the surface.

The nickel-iron combined oxidation state nanosheet substance comprises one or more of nickel hydroxide, ferric hydroxide and ferrous hydroxide, and also comprises one or more of iron-doped nickel hydroxide, nickel-doped ferric hydroxide and nickel-doped ferrous hydroxide.

The preparation process comprises the following steps:

1) acid soaking and cleaning the metal nickel-iron substrate at normal temperature and normal pressure to obtain a fresh metal nickel-iron substrate;

2) and (3) soaking the obtained fresh metal nickel-iron substrate in deionized water at normal temperature and normal pressure to obtain the electrode with the surface growing with the nickel-iron combined oxidation state nano sheet substance.

Further, the step 1) is specifically that the metal nickel-iron substrate is placed in an acetone solution for ultrasonic cleaning for 10-30 minutes at normal temperature and normal pressure, and then repeatedly cleaned by ethanol to remove a metal surface grease layer; and then placing the metal substrate in an acid solution with the concentration of 1-9 mol per liter for carrying out surface oxidation layer corrosion treatment for 30-120 minutes, finally washing the metal substrate with distilled water, and removing the metal surface oxidation layer to obtain the fresh metal ferronickel substrate.

Further, the metal nickel-iron substrate adopts one of nickel-iron net, foam nickel-iron and nickel-iron sheet.

Further, based on the acid solution, the acid is one or more of hydrochloric acid, nitric acid, sulfuric acid, acetic acid and oxalic acid, and the total concentration of acid radical ions in the acid solution is 0.1-9 mol per liter; the acid solution also contains one or more of reducing agents of hydrazine, hydroxylamine, sodium borohydride, potassium borohydride and lithium aluminum hydride.

Further, the step 2) is specifically to place a fresh metal ferronickel substrate in deionized water at normal temperature and normal pressure, soak for 12-72 hours, and naturally dry in air to obtain the electrode with the surface growing with the ferronickel combined oxidation state nanosheet substance.

Compared with the prior art, the invention has the following advantages and effects:

(1) the preparation process of the electrode is simple, no metal ion source is introduced externally, and an active catalyst layer is formed on the surface of the electrode substrate by directly modifying the electrode substrate to carry out electrocatalytic oxygen evolution reaction. Cleaning treatment is carried out to remove grease, impurities and metal oxides on the surface of the ferronickel metal, so that the fresh surface of the metallic ferronickel is exposed. The fresh metallic ferronickel has higher activity, and generates metal hydroxide, namely ferronickel combined oxidation state substance, by chemical reaction with water and dissolved oxygen in water. The nickel-iron combined oxidation state substance essentially has the electrocatalytic oxygen evolution reaction performance far beyond that of the super-metal nickel-iron, so that the prepared electrode has greatly improved electrocatalytic oxygen evolution reaction performance.

(2) The ferronickel combined oxidation state substance directly comes from the electrode metal substrate, is derived from the metallic ferronickel element, does not have a strict phase interface with the electrode metal substrate, and increases the adhesion strength between the generated active substance and the electrode metal substrate, so the structural stability of the electrode is stronger, and the service life is prolonged.

(3) The ferronickel combined oxidation state substance is of a nanosheet structure and has abundant surface area, so that abundant catalytic active sites are provided.

(4) The preparation process only needs a certain amount of acid solution and deionized water, and has low cost of raw materials and little pollution. In addition, the preparation process only needs mild conditions of normal temperature and normal pressure, and is easy for scale-up production.

Drawings

Fig. 1 is a scanning electron microscope picture of the surface of the nickel-iron net of the invention without any treatment.

FIG. 2 is a scanning electron microscope image of the electrode surface in example 1 of the present invention.

FIG. 3 is a scanning electron microscope image of the electrode surface in example 2 of the present invention.

FIG. 4 is a SEM image of the surface of an electrode in example 3 of the present invention.

FIG. 5 is a plot of a three-electrode electrolytic voltammetric sweep of examples of the invention and comparative examples.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the present invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the present invention and is not intended to limit the scope of the claims which follow.

All of the starting materials of the present invention, without particular limitation as to their source, may be purchased commercially or prepared according to conventional methods well known to those skilled in the art.

In the present invention, the normal temperature and pressure refers to an environment of 25 ℃ and 1 standard atmospheric pressure.

The invention provides a preparation process of a nanosheet modified electrode at normal temperature and normal pressure, which comprises the following steps:

step 1): acid soaking and cleaning the metal nickel-iron substrate at normal temperature and normal pressure to obtain a fresh metal nickel-iron substrate;

specifically, the metal nickel-iron substrate is placed in an acetone solution for ultrasonic cleaning for 10-30 minutes at normal temperature and normal pressure, and then repeatedly cleaned by ethanol to remove a metal surface grease layer; and then placing the metal substrate in an acid solution with the concentration of 1-9 mol per liter for carrying out surface oxidation layer corrosion treatment for 30-120 minutes, finally washing the metal substrate with distilled water, removing the metal surface oxidation layer, and drying to obtain the fresh metal ferronickel substrate. Wherein, the metal ferronickel substrate adopts one of nickel-iron net, foam ferronickel and nickel-iron sheet; the acid is hydrochloric acid (HCl) or nitric acid (HNO)₃) Sulfuric acid (H)₂SO₄) Acetic acid (CH)₃COOH), oxalic acid (H)₂C₂O₄) The total concentration of acid radical ions in the acid solution is 0.1-9 mol per liter; the acid solution also contains a reducing agent hydrazine (N)₂H₄) Hydroxylamine (C)₆H₇NO), sodium borohydride (NaBH)₄) Potassium borohydride (KBH)₄) Lithium aluminum hydride (LiAlH)₄) One or more of them.

Step 2): and (3) soaking the obtained fresh metal nickel-iron substrate in deionized water at normal temperature and normal pressure to obtain the electrode with the surface growing with the nickel-iron combined oxidation state nano sheet substance.

Specifically, under normal temperature and normal pressure, a fresh metal ferronickel substrate is placed in deionized water, soaked for 12-72 hours, and then naturally dried in air to obtain an electrode with a ferronickel combined oxidation state nanosheet substance growing on the surface.

Further, growing an electrode based on the surface with a nickel-iron combined oxidation state nanosheet substance; the nickel iron combination oxidation state nanosheet material comprises nickel hydroxide (Ni (OH)₂) Iron hydroxide (Fe (OH))₃) Ferrous hydroxide (Fe (OH)₂) One or more of the above-mentioned materials, and at the same time, also contains iron-doped nickel hydroxide (Fe)_xNi_1-x(OH)₂) Nickel doped iron (Ni) hydroxide_xFe_1-x(OH)₃) Nickel doped ferrous hydroxide (Ni)_xFe_1-x(OH)₂) One or more of them.

The present invention will be further illustrated by the following specific examples.

Example 1

The embodiment provides an electrode preparation method based on foam iron-nickel nanosheet modification.

Cleaning a metal nickel-iron net:

placing the metal nickel-iron mesh in an acetone solution, ultrasonically cleaning for 10-30 minutes, and repeatedly cleaning with ethanol to remove an oil layer on the surface of the metal; then, placing the metal substrate in a hydrochloric acid solution with the concentration of 1 mol per liter for carrying out surface oxide layer corrosion treatment for 90 minutes, wherein the hydrochloric acid solution contains sodium borohydride and potassium borohydride, and the total concentration of reducing agents in the acid solution is 0.05 mol per liter; finally, the nickel-iron substrate is washed clean by distilled water, the oxide layer on the surface of the metal is removed, and the fresh metal nickel-iron substrate is obtained after drying.

(II) cleaning the treated metal nickel-iron net to prepare the nanosheet modified electrode:

the cleaned metal nickel-iron net is placed in deionized water, soaked for 24 hours at room temperature, and then naturally dried in the air to obtain the electrode of the embodiment.

(III) analyzing the surface structure of the electrode:

fig. 1 shows the scanning electron microscope picture of the surface of the metal nickel-iron net without any treatment, which shows the clean and smooth characteristic. Fig. 2 shows a scanning electron microscope picture of the electrode surface obtained in this embodiment, which shows a nanosheet array structure.

(IV) analyzing the oxygen evolution catalytic performance of the electrode:

the electrode obtained in this example was tested for oxygen evolution performance using a linear voltammetric sweep test method. The test uses a three-electrode system, the electrode obtained in this example is a working electrode, mercury/mercury oxide is a reference electrode, a platinum mesh is an auxiliary electrode, the electrolyte is potassium hydroxide solution with a mass of 1 mol per liter, the scanning rate is 5 millivolts per second, and the scanning range is 0 volt to 1 volt. The oxygen evolution performance was tested on an electrochemical workstation (CHI760E, Shanghai Chenghua instruments, Inc.) and the test results correspond to FIG. 2 and Table 1, where J is the current density and the unit mA cm^-2Milliamps per square centimeter; e is the potential difference, and the unit V is volt; control sample 1 is comparative example 1, Control sample 2 is comparative example 2, Control sample 3 is comparative example 3, and Control sample 4 is comparative example 4; sample 1 is example 1, Sample 2 is example 2, and Sample 3 is example 3; Hg/HgO is a mercury/mercury oxide reference electrode filled with 1 mole per liter of potassium hydroxide solution.

Table 1: overpotential of different test electrodes under different current densities

Example 2

The embodiment provides a preparation method of an electrode modified by a nanosheet based on a metal nickel-iron net.

Cleaning a metal nickel-iron net:

placing the metal nickel-iron mesh in an acetone solution, ultrasonically cleaning for 10-30 minutes, and repeatedly cleaning with ethanol to remove an oil layer on the surface of the metal; then, placing the metal substrate in a hydrochloric acid solution with the concentration of 3 mol per liter for carrying out surface oxide layer corrosion treatment for 90 minutes, wherein the hydrochloric acid solution contains sodium borohydride and potassium borohydride, and the total concentration of reducing agents in the acid solution is 0.05 mol per liter; finally, the nickel-iron substrate is washed clean by distilled water, the oxide layer on the surface of the metal is removed, and the fresh metal nickel-iron substrate is obtained after drying.

(II) cleaning the treated metal nickel-iron net to prepare the nanosheet modified electrode:

the cleaned metal nickel-iron net is placed in deionized water, soaked for 24 hours at room temperature, and then naturally dried in the air to obtain the electrode of the embodiment.

(III) analyzing the oxygen evolution catalytic performance of the electrode:

the electrode obtained in this example was tested for oxygen evolution performance using a linear voltammetric sweep test method. The test uses a three-electrode system, the electrode obtained in this example is a working electrode, mercury/mercury oxide is a reference electrode, a platinum mesh is an auxiliary electrode, the electrolyte is potassium hydroxide solution with a mass of 1 mol per liter, the scanning rate is 5 millivolts per second, and the scanning range is 0 volt to 1 volt. The oxygen evolution performance was tested on an electrochemical workstation (CHI760E, shanghai chenhua instruments ltd) and the test results corresponded to fig. 3 and table 1.

Example 3

The embodiment provides a preparation method of an electrode modified by a nanosheet based on a metal nickel-iron net.

Cleaning a metal nickel-iron net:

placing the metal nickel-iron mesh in an acetone solution, ultrasonically cleaning for 10-30 minutes, and repeatedly cleaning with ethanol to remove an oil layer on the surface of the metal; then, placing the metal substrate in a hydrochloric acid solution with the concentration of 6 mol per liter for carrying out surface oxide layer corrosion treatment for 90 minutes, wherein the hydrochloric acid solution contains sodium borohydride and potassium borohydride, and the total concentration of reducing agents in the acid solution is 0.05 mol per liter; finally, the nickel-iron substrate is washed clean by distilled water, the oxide layer on the surface of the metal is removed, and the fresh metal nickel-iron substrate is obtained after drying.

(II) cleaning the treated metal nickel-iron net to prepare the nanosheet modified electrode:

the cleaned metal nickel-iron net is placed in deionized water, soaked for 24 hours at room temperature, and then naturally dried in the air to obtain the electrode of the embodiment.

(III) analyzing the surface structure of the electrode:

fig. 4 shows a scanning electron microscope image of the electrode surface obtained in this embodiment, which shows a nanosheet array structure.

(IV) analyzing the oxygen evolution catalytic performance of the electrode:

the electrode obtained in this example was tested for oxygen evolution performance using a linear voltammetric sweep test method. The test uses a three-electrode system, the electrode obtained in this example is a working electrode, mercury/mercury oxide is a reference electrode, a platinum mesh is an auxiliary electrode, the electrolyte is potassium hydroxide solution with a mass of 1 mol per liter, the scanning rate is 5 millivolts per second, and the scanning range is 0 volt to 1 volt. The oxygen evolution performance was tested on an electrochemical workstation (CHI760E, shanghai chenhua instruments ltd) and the test results corresponded to table 1.

Comparative example 1

This comparative example directly used a metallic nickel-iron mesh as the electrode.

Cleaning a metal nickel-iron net:

placing the metal nickel-iron mesh in an acetone solution, ultrasonically cleaning for 10-30 minutes, and repeatedly cleaning with ethanol to remove an oil layer on the surface of the metal; and then soaking the metal nickel-iron net in deionized water for 24 hours, and finally naturally drying in air to obtain the comparative electrode.

(II) analyzing the oxygen evolution catalytic performance of the electrode:

and testing the oxygen evolution performance of the electrode obtained in the comparative example by adopting a linear voltammetry scanning test method. The test uses a three-electrode system, the electrode obtained in the comparative example is a working electrode, mercury/mercury oxide is a reference electrode, a platinum mesh is an auxiliary electrode, the electrolyte adopts potassium hydroxide solution with the mass of 1 mol per liter, the scanning speed is 5 millivolts per second, and the scanning range is 0 volt to 1 volt. The oxygen evolution performance was tested on an electrochemical workstation (CHI760E, shanghai chenhua instruments ltd) and the test results corresponded to table 1.

Comparative example 2

This comparative example directly used a metallic nickel-iron mesh as the electrode.

Cleaning a metal nickel-iron net:

placing the metal nickel-iron mesh in an acetone solution, ultrasonically cleaning for 10-30 minutes, and repeatedly cleaning with ethanol to remove an oil layer on the surface of the metal; then, the ferronickel mesh is placed in hydrochloric acid solution with the concentration of 3 mol per liter for soaking for 90 minutes, and the hydrochloric acid solution also contains one or more of reducing agents of hydrazine, hydroxylamine, sodium borohydride, potassium borohydride and lithium aluminum hydride; and repeatedly cleaning with distilled water to remove the oxide layer on the metal surface, and naturally drying in the air to obtain the comparative electrode.

(II) analyzing the oxygen evolution catalytic performance of the electrode:

and testing the oxygen evolution performance of the electrode obtained in the comparative example by adopting a linear voltammetry scanning test method. The test uses a three-electrode system, the electrode obtained in the comparative example is a working electrode, mercury/mercury oxide is a reference electrode, a platinum mesh is an auxiliary electrode, the electrolyte adopts potassium hydroxide solution with the mass of 1 mol per liter, the scanning speed is 5 millivolts per second, and the scanning range is 0 volt to 1 volt. The oxygen evolution performance was tested on an electrochemical workstation (CHI760E, shanghai chenhua instruments ltd) and the test results corresponded to table 1.

Comparative example 3

This comparative example directly used a metallic nickel-iron mesh as the electrode.

Cleaning a metal nickel-iron net:

placing the metal nickel-iron mesh in an acetone solution, ultrasonically cleaning for 10-30 minutes, and repeatedly cleaning with ethanol to remove an oil layer on the surface of the metal; then repeatedly washed with distilled water and finally naturally dried in the air to obtain the comparative electrode.

(II) analyzing the oxygen evolution catalytic performance of the electrode:

and testing the oxygen evolution performance of the electrode obtained in the comparative example by adopting a linear voltammetry scanning test method. The test uses a three-electrode system, the electrode obtained in the comparative example is a working electrode, mercury/mercury oxide is a reference electrode, a platinum mesh is an auxiliary electrode, the electrolyte adopts potassium hydroxide solution with the mass of 1 mol per liter, the scanning speed is 5 millivolts per second, and the scanning range is 0 volt to 1 volt. The oxygen evolution performance was tested on an electrochemical workstation (CHI760E, shanghai chenhua instruments ltd) and the test results corresponded to table 1.

Comparative example 4

This comparative example directly used a metallic nickel-iron mesh as the electrode.

Cleaning a metal nickel-iron net:

placing the metal nickel-iron mesh in an acetone solution, ultrasonically cleaning for 10-30 minutes, and repeatedly cleaning with ethanol to remove an oil layer on the surface of the metal; then, the ferronickel mesh is placed in hydrochloric acid solution with the concentration of 3 mol per liter for soaking for 90 minutes, and the hydrochloric acid solution also contains one or more of reducing agents of hydrazine, hydroxylamine, sodium borohydride, potassium borohydride and lithium aluminum hydride; and repeatedly cleaning with distilled water to remove an oxide layer on the surface of the metal, then soaking the metal nickel-iron net in ethanol for 24 hours, and finally naturally drying in the air to obtain the comparative electrode.

(II) analyzing the oxygen evolution catalytic performance of the electrode:

and testing the oxygen evolution performance of the electrode obtained in the comparative example by adopting a linear voltammetry scanning test method. The test uses a three-electrode system, the electrode obtained in the comparative example is a working electrode, mercury/mercury oxide is a reference electrode, a platinum mesh is an auxiliary electrode, the electrolyte adopts potassium hydroxide solution with the mass of 1 mol per liter, the scanning speed is 5 millivolts per second, and the scanning range is 0 volt to 1 volt. The oxygen evolution performance was tested on an electrochemical workstation (CHI760E, shanghai chenhua instruments ltd) and the test results corresponded to table 1.

Compared with the pure nickel-iron electrode, the nickel-iron electrode modified by the nano-sheets at normal temperature and normal pressure has obviously improved electrocatalytic performance from the comparative analysis of the electrode oxygen evolution catalytic performance data. From the surface of the electrode structure, the surface of the metal nickel-iron net is obviously generated with a nano-sheet structure through normal-temperature normal-pressure oxidation, deionized water soaking and natural drying treatment in air under an acidic condition, the acid concentration is different, and the scale of the generated nano-sheet structure is different; and no obvious nano-sheet structure is generated on the surface of the metal nickel-iron net after normal-temperature normal-pressure oxidation, ethanol soaking and natural drying treatment in air under an acidic condition, so that the importance and the necessity of deionized water soaking on the generation of the nano-sheet structure are shown. From the analysis of data results of three-electrode tests, the metal nickel-iron network has obvious electrocatalytic oxygen evolution performance improvement by adopting normal-temperature normal-pressure oxidation treatment under acidic conditions, especially under high current density (100mA cm)^-2) At this point, there is almost 160m compared to pure Fe-Ni meshThe potential of V decreases.