CN114959767A - Nickel-based active cathode and preparation method thereof - Google Patents

Abstract

A nickel-based active cathode and a preparation method thereof comprise a conductive matrix of a nickel substrate, wherein the conductive matrix is made of a nickel screen, the outer surface of the conductive matrix is coated with a metal oxide catalyst intermediate layer, and the outer surface of the metal oxide catalyst intermediate layer is coated with a metal monatomic catalyst surface layer; the metal oxide catalyst intermediate layer is composed of oxides of noble metal elements and oxides of lanthanide elements, and the metal oxide coating comprises 75-85 mol% of noble metal elements and 15-25 mol% of lanthanide elements according to metal components; the metal monatomic catalyst surface layer is composed of a noble metal element. The nickel-based active cathode and the preparation method thereof have the advantages of simple process, easy operation and low manufacturing cost, can effectively absorb reverse current, inhibit cathode degradation caused by the reverse current when electrolysis is stopped, inhibit damage of the reverse current to a cathode surface net and reduce electric energy consumption.

Description

Nickel-based active cathode and preparation method thereof

Technical Field

The invention relates to the field of sodium hydroxide preparation, in particular to a nickel-based active cathode and a preparation method thereof.

Background

In the ion-membrane process caustic soda electrolysis production apparatus, when production is stopped, free chlorine present in the solution in the electrolytic cell is discharged on the electrode due to the galvanic effect and forms a current loop, and a reverse current is inevitably generated in the electrolytic cell.

The reverse current generation mechanism:

in the electrolytic process of the ionic membrane electrolytic cell, the unit cell is polarized from an equilibrium state, and the following electrolytic reactions respectively occur at an anode and a cathode:

anode: 2Cl ^- －2e-＝Cl ₂

Cathode: 2H ₂ O+2e-＝H ₂ +2OH-

When the current was cut off, the cell returned to equilibrium, but the composition of the anolyte changed and (Cl) was present in the anolyte ^- /Cl ₂ ) Electric pair, present in catholyte (H) ₂ +OH ^- /H ₂ O) electricity pair, and conductive liquid is in the inlet and outlet pipelines of the cathode and the anode, so that a primary battery is formed, and the following primary battery reaction occurs:

anode: cl ₂ +2e-＝2Cl ^-

Cathode: h ₂ +2OH ^- －2e-＝2H ₂ O

Thereby forming a reverse current.

Hazard of reverse current:

due to H ₂ Very low solubility in catholyte (H in 21% NaOH) ₂ Has a solubility of about 2mL/m ³ ＝0.1mol/m ³ ) And Cl ₂ Has high solubility (about 1 g) in anolyte/L＝14mol/m ³ In the actual electrolysis process, the available chlorine in the anolyte is about 1.5-2.0 g/L), so that the H in the catholyte ₂ Not enough to complete the above galvanic reaction, Cl ₂ There is a strong driving force at the anode causing the cathode itself in the cathode chamber to be oxidized by the reverse current.

The ion membrane electrolysis alkali preparation technology is considered as the most advanced, economical and reasonable alkali preparation method in the world due to the advantages of energy conservation, high product quality, no pollution and the like. In recent years, the ion membrane method electrolysis technology is continuously innovated, the main aim is to reduce the direct current power consumption, and particularly, the electricity-saving effect is very obvious after the membrane polar distance electrolysis bath operates. However, the service life of the electrolytic cell of users is greatly different due to the different operation conditions of the electrolytic cell, mainly the frequent stop during the start-up process. When the electrolytic cell stops electrolysis, the anode has a (Cl-/Cl 2) electric pair, and the cathode has a (H2+ OH-/H2O) electric pair. When the electrolytic cell is stopped and electrolysis is stopped, chlorine atoms in the anolyte are reduced to chloride ions to cause a reduction reaction, and the cathode undergoes an oxidation reaction of the metal. With the development of large-scale electrolytic cells, the cumulative effect of reverse current is more obvious, and the elimination and control of the reverse current are important conditions for long-period and low-energy consumption stable operation of the electrolytic cells, so that the stress resistance and reverse current capability of the electrodes are improved, and the positive significance is achieved on reducing the operation cost and increasing the market competitiveness.

Disclosure of Invention

The invention aims to provide a nickel-based active cathode and a preparation method thereof, wherein the nickel-based active cathode has the advantages of simple process, easy operation and low manufacturing cost, can reduce the hydrogen evolution potential of the cathode, effectively resist reverse current, inhibit damage of the reverse current to a cathode surface net and reduce electric energy consumption.

The nickel-based active cathode comprises a conductive matrix of a nickel base material, wherein the conductive matrix is made of a nickel screen, a metal oxide catalyst intermediate layer is coated on the outer surface of the conductive matrix of the nickel base material, and a metal monatomic catalyst surface layer is coated on the outer surface of the metal oxide catalyst intermediate layer;

the metal oxide catalyst intermediate layer is composed of oxides of noble metal elements and lanthanide elements, the thickness of the metal oxide catalyst intermediate layer is 6-15 μm, and the mole percentage of the noble metal elements is 75-85% and the mole percentage of the lanthanide elements is 15-25% in the metal oxide coating according to the metal components;

the surface layer of the metal monatomic catalyst is composed of noble metal elements, and the thickness of the surface layer of the metal monatomic catalyst is 1-4 μm;

the nickel-based active cathode is prepared by the following steps:

A. preparing a conductive matrix of a nickel substrate by using a nickel wire mesh, cleaning the conductive matrix, removing dirt on the surface of the conductive matrix, and roughening the surface of the conductive matrix;

B. preparing soluble nitrate of lanthanide and soluble nitrate of noble metal element, respectively dissolving the soluble nitrate of lanthanide and the soluble nitrate of noble metal element in water to obtain soluble nitrate solution of lanthanide and noble metal nitrate solution for later use;

C. b, mixing the lanthanide soluble nitrate solution and the noble metal nitrate solution obtained in the step B according to the proportion that the mole percentage of the noble metal element is 75-85 percent and the mole percentage of the lanthanide is 15-25 percent, wherein the concentration of the noble metal in the mixed solution is 100-120 g/L, and obtaining the mixed solution;

D. regulating and controlling the concentration of the noble metal in the noble metal nitrate solution prepared in the step B to be 50-80 g/L to obtain a noble metal nitrate coating solution;

E. coating the mixed solution obtained in the step C on the conductive substrate treated in the step A, and heating the conductive substrate to 100-300 ℃ in air atmosphere for 10-50 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 400-600 ℃ for 10-50 minutes to obtain the conductive substrate with the outer surface coated with the metal oxide catalyst intermediate layer;

F. repeating the step E until the thickness of the metal oxide catalyst intermediate layer on the surface of the conductive substrate is 6-15 μm;

G. coating the noble metal nitrate coating solution obtained in the step D on the conductive substrate treated in the step F, and heating the conductive substrate to 100-200 ℃ in inert gas atmosphere for 10-30 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 350-550 ℃ for 10-30 minutes to obtain the conductive substrate with the outer surface of the metal oxide catalyst intermediate layer coated with the metal monatomic catalyst surface layer;

H. and G, repeating the step until the thickness of the metal monatomic catalyst surface layer on the surface of the conductive base material is 1-4 mu m, thus obtaining the nickel-based active cathode.

The noble metal element is ruthenium, rhodium, palladium, osmium, iridium, platinum, gold or silver, and the lanthanide element is lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium or lutetium.

Preferably, the noble metal nitrate comprises ruthenium nitrate, palladium nitrate, iridium nitrate, platinum nitrate and silver nitrate, and the metal oxide coating contains 78-82 mol% of noble metal elements and 18-22 mol% of lanthanide elements according to metal components;

the mole percentage of noble metal element in the surface layer of the metal monatomic catalyst is 78% -82%, and the mole percentage of lanthanide element is 18% -22%.

Preferably, the metal oxide coating contains 80 mol% of noble metal element and 20 mol% of lanthanide element according to metal component;

the mole percentage of the noble metal element in the surface layer of the metal single-atom catalyst is 80 percent, and the mole percentage of the lanthanide element is 20 percent.

Preferably, in the step E, the mixed solution obtained in the step C is coated on the conductive substrate treated in the step A, and the conductive substrate is heated to 150-250 ℃ in the air atmosphere for 20-40 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 450-550 ℃ for 20-40 minutes to obtain the conductive substrate with the outer surface coated with the metal oxide catalyst intermediate layer;

step G, coating the noble metal nitrate coating solution obtained in step D on the conductive substrate treated in step F, and heating the conductive substrate to 120-180 ℃ in an inert gas atmosphere for 15-25 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 400-500 ℃ for 15-25 minutes to obtain the conductive substrate with the surface layer of the metal monatomic catalyst coated on the outer surface of the intermediate layer of the metal oxide catalyst.

The preparation method of the nickel-based active cathode comprises the following steps:

A. preparing a conductive matrix of a nickel substrate by using a nickel wire mesh, cleaning the conductive matrix, removing dirt on the surface of the conductive matrix, and roughening the surface of the conductive matrix;

B. preparing soluble nitrate of lanthanide and soluble nitrate of noble metal element, respectively dissolving the soluble nitrate of lanthanide and the soluble nitrate of noble metal element in water to obtain soluble nitrate solution of lanthanide and noble metal nitrate solution for later use;

C. b, mixing the lanthanide soluble nitrate solution and the noble metal nitrate solution obtained in the step B according to the proportion that the mole percentage of the noble metal elements is 75-85 percent and the mole percentage of the lanthanide elements is 15-25 percent, wherein the concentration of the noble metal in the mixed solution is 100-120 g/L, and obtaining the mixed solution;

D. regulating and controlling the concentration of the noble metal in the noble metal nitrate solution prepared in the step B to be 50-80 g/L to obtain a noble metal nitrate coating solution;

E. coating the mixed solution obtained in the step C on the conductive substrate treated in the step A, and heating the conductive substrate to 100-300 ℃ in air atmosphere for 10-50 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive base material to 400-600 ℃ for 10-50 minutes to obtain the conductive base material of which the outer surface is coated with the metal oxide catalyst intermediate layer;

F. repeating the step E until the thickness of the metal oxide catalyst intermediate layer on the surface of the conductive substrate is 6-15 μm;

G. coating the noble metal nitrate coating solution obtained in the step D on the conductive substrate treated in the step F, and heating the conductive substrate to 100-200 ℃ in inert gas atmosphere for 10-30 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 350-550 ℃ for 10-30 minutes to obtain the conductive substrate with the surface layer of the metal monatomic catalyst coated on the outer surface of the metal oxide catalyst intermediate layer;

H. and G, repeating the step until the thickness of the metal monatomic catalyst surface layer on the surface of the conductive base material is 1-4 mu m, thus obtaining the nickel-based active cathode.

Preferably, the noble metal nitrates include ruthenium nitrate, palladium nitrate, iridium nitrate, platinum nitrate and silver nitrate.

Preferably, the metal oxide coating contains 78 to 82 mole percent of noble metal elements and 18 to 22 mole percent of lanthanide elements according to metal components;

the mole percentage of noble metal element in the surface layer of the metal single-atom catalyst is 78% -82%, and the mole percentage of lanthanide element is 18% -22%.

Preferably, the metal oxide coating contains 80 mol% of noble metal element and 20 mol% of lanthanide element according to metal component;

the mole percentage of the noble metal element in the metal monatomic catalyst surface layer is 80%, and the mole percentage of the lanthanide element is 20%.

Preferably, in the step E, the mixed solution obtained in the step C is coated on the conductive substrate treated in the step A, and the conductive substrate is heated to 150-250 ℃ in the air atmosphere for 20-40 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 450-550 ℃ for 20-40 minutes to obtain the conductive substrate with the outer surface coated with the metal oxide catalyst intermediate layer;

step G, coating the noble metal nitrate coating solution obtained in step D on the conductive substrate treated in step F, and heating the conductive substrate to 120-180 ℃ in an inert gas atmosphere for 15-25 minutes to obtain a first heat-treated conductive substrate;

and then heating the first heat-treated conductive substrate to 400-500 ℃ for 15-25 minutes to obtain the conductive substrate with the metal monoatomic catalyst surface layer coated on the outer surface of the metal oxide catalyst intermediate layer.

Preferably, in the step E, the mixed solution obtained in the step C is coated on the conductive substrate treated in the step A, and the conductive substrate is heated to 180-220 ℃ in the air atmosphere for 25-35 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 480-520 ℃ for 25-35 minutes to obtain the conductive substrate with the outer surface of the conductive substrate coated with the metal oxide catalyst intermediate layer;

step G, coating the noble metal nitrate coating solution obtained in step D on the conductive substrate treated in step F, and heating the conductive substrate to 140-160 ℃ in an inert gas atmosphere for 18-22 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 430-470 ℃ for 18-22 minutes to obtain the conductive substrate with the surface layer of the metal monatomic catalyst coated on the outer surface of the intermediate layer of the metal oxide catalyst.

The nickel-based active cathode is characterized in that a conductive substrate is made of a nickel screen, a metal oxide catalyst intermediate layer is coated on the outer surface of the conductive substrate of a nickel substrate, a metal monoatomic catalyst surface layer is coated on the outer surface of the metal oxide catalyst intermediate layer, and a series of special treatment steps are adopted, so that the atomic compositions among the conductive substrate, the metal oxide catalyst intermediate layer and the metal monoatomic catalyst surface layer have certain gradient change, the gradient change can obviously slow down the heat effect among the conductive substrate, the metal oxide catalyst intermediate layer and the metal monoatomic catalyst surface layer, the heat stress is reduced, cracks generated among the conductive substrate, the metal oxide catalyst intermediate layer and the metal monoatomic catalyst surface layer can be reduced, the conductive substrate is increased, the metal monoatomic catalyst surface layer is increased, and the metal monoatomic catalyst surface layer is coated with a metal monoatomic catalyst surface layer, The binding force between the metal oxide catalyst intermediate layer and the metal monatomic catalyst surface layer can obviously prolong the service life of the electrode and improve the anti-adversity and anti-current capacity of the electrode. Therefore, the nickel-based active cathode and the preparation method thereof have the characteristics of simple process, easy operation, low manufacturing cost, capability of effectively resisting and absorbing reverse current, inhibiting cathode degradation caused by the reverse current when the electrolysis is stopped, inhibiting damage of the reverse current to a cathode surface net and increase of the tank pressure, and reducing the electric energy consumption.

Further details and characteristics of the nickel-based active cathode according to the invention and of the method for its preparation will be clear from a reading of the examples described in detail below.

Drawings

FIG. 1a is a surface topography of a nickel-based active cathode prepared according to comparative example 1 of the present invention;

FIG. 1b is a surface topography of a nickel-based active cathode prepared in example 1 of the present invention;

FIG. 2a is a cross-sectional profile of a nickel-based active cathode prepared according to comparative example 2 of the present invention;

FIG. 2b is a cross-sectional profile of a nickel-based active cathode prepared in example 2 of the present invention;

FIG. 3 is a graph comparing the hydrogen evolution potential at a current density of 4kA/m2 for 3 examples of the invention and 4 comparative examples of the invention;

FIG. 4 is a graph comparing the residual Ru content of nickel-based active cathodes prepared according to 3 examples of the invention and 4 comparative examples of the invention after multiple reverse charging;

fig. 5 is a graph comparing the Pt residues remaining in the coating after multiple reversals of current for 3 examples of the invention and 4 comparative examples of the invention.

Detailed Description

The nickel-based active cathode comprises a conductive substrate of a nickel base material, wherein the conductive substrate is made of a nickel screen, a metal oxide catalyst intermediate layer is coated on the outer surface of the conductive substrate of the nickel base material, and a metal monatomic catalyst surface layer is coated on the outer surface of the metal oxide catalyst intermediate layer;

the metal oxide catalyst intermediate layer is composed of oxides of noble metal elements and lanthanide elements, the thickness of the metal oxide catalyst intermediate layer is 6-15 μm, and the mole percentage of the noble metal elements is 75-85% and the mole percentage of the lanthanide elements is 15-25% in the metal oxide coating according to the metal components;

the surface layer of the metal monatomic catalyst is composed of noble metal elements, and the thickness of the surface layer of the metal monatomic catalyst is 1-4 μm;

the nickel-based active cathode is prepared by the following steps:

A. preparing a conductive matrix of a nickel substrate by using a nickel wire mesh, cleaning the conductive matrix, removing dirt on the surface of the conductive matrix, and roughening the surface of the conductive matrix;

B. preparing soluble nitrate of lanthanide and soluble nitrate of noble metal element, respectively dissolving the soluble nitrate of lanthanide and the soluble nitrate of noble metal element in water to obtain soluble nitrate solution of lanthanide and noble metal nitrate solution for later use;

C. b, mixing the lanthanide soluble nitrate solution and the noble metal nitrate solution obtained in the step B according to the proportion that the mole percentage of the noble metal elements is 75-85 percent and the mole percentage of the lanthanide elements is 15-25 percent, wherein the concentration of the noble metal in the mixed solution is 100-120 g/L, and obtaining the mixed solution;

D. regulating and controlling the concentration of the noble metal in the noble metal nitrate solution prepared in the step B to be 50-80 g/L to obtain a noble metal nitrate coating solution;

E. coating the mixed solution obtained in the step C on the conductive substrate treated in the step A, and heating the conductive substrate to 100-300 ℃ in air atmosphere for 10-50 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 400-600 ℃ for 10-50 minutes to obtain the conductive substrate with the outer surface coated with the metal oxide catalyst intermediate layer;

F. repeating the step E until the thickness of the metal oxide catalyst intermediate layer on the surface of the conductive substrate is 6-15 μm;

G. d, coating the noble metal nitrate coating solution obtained in the step D on the conductive substrate treated in the step F, and heating the conductive substrate to 100-200 ℃ in an inert gas atmosphere for 10-30 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 350-550 ℃ for 10-30 minutes to obtain the conductive substrate with the surface layer of the metal monatomic catalyst coated on the outer surface of the metal oxide catalyst intermediate layer;

H. and G, repeating the step until the thickness of the metal monatomic catalyst surface layer on the surface of the conductive base material is 1-4 mu m, thus obtaining the nickel-based active cathode.

The noble metal element is ruthenium, rhodium, palladium, osmium, iridium, platinum, gold or silver, and the lanthanide element is lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium or lutetium.

As a further improvement of the invention, the noble metal nitrates comprise ruthenium nitrate, palladium nitrate, iridium nitrate, platinum nitrate and silver nitrate, and the metal oxide coating comprises 78-82 mol% of noble metal elements and 18-22 mol% of lanthanide elements according to metal components;

the mole percentage of noble metal element in the surface layer of the metal monatomic catalyst is 78% -82%, and the mole percentage of lanthanide element is 18% -22%.

As a further improvement of the invention, in the metal oxide coating, the mole percentage of the noble metal element is 80% and the mole percentage of the lanthanide element is 20% based on the metal component;

the mole percentage of the noble metal element in the metal monatomic catalyst surface layer is 80%, and the mole percentage of the lanthanide element is 20%.

As a further improvement of the present invention, in the step E, the mixed solution obtained in the step C is coated on the conductive substrate treated in the step a, and the conductive substrate is heated to 150 ℃ to 250 ℃ for 20 minutes to 40 minutes in an air atmosphere to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 450-550 ℃ for 20-40 minutes to obtain the conductive substrate with the outer surface coated with the metal oxide catalyst intermediate layer;

step G, coating the noble metal nitrate coating solution obtained in step D on the conductive substrate treated in step F, and heating the conductive substrate to 120-180 ℃ in an inert gas atmosphere for 15-25 minutes to obtain a first heat-treated conductive substrate;

and then heating the first heat-treated conductive substrate to 400-500 ℃ for 15-25 minutes to obtain the conductive substrate with the metal monoatomic catalyst surface layer coated on the outer surface of the metal oxide catalyst intermediate layer.

The preparation method of the nickel-based active cathode comprises the following steps:

A. preparing a conductive matrix of a nickel substrate by using a nickel wire mesh, cleaning the conductive matrix, removing dirt on the surface of the conductive matrix, and roughening the surface of the conductive matrix;

the conductive matrix of the nickel-based active cathode adopts a woven nickel screen, and the nickel screen needs to be subjected to pretreatment such as sanding, ultrasonic cleaning, drying and the like in the using process. Sanding is performed to enhance the roughness of the surface of the conductive substrate, so that the active catalyst layer can obtain sufficient adhesion and stability. Compared with the traditional acid washing technology, the ultrasonic cleaning can remove the sand on the surface of the nickel wire mesh more environmentally friendly without damaging the roughness of the surface of the conductive substrate.

B. Preparing soluble nitrate of lanthanide and soluble nitrate of noble metal element, respectively dissolving the soluble nitrate of lanthanide and the soluble nitrate of noble metal element in water to obtain soluble nitrate solution of lanthanide and noble metal nitrate solution for later use;

C. b, mixing the lanthanide soluble nitrate solution and the noble metal nitrate solution obtained in the step B according to the proportion that the mole percentage of the noble metal element is 75-85 percent and the mole percentage of the lanthanide is 15-25 percent, wherein the concentration of the noble metal in the mixed solution is 100-120 g/L, and obtaining the mixed solution;

D. regulating and controlling the concentration of the noble metal in the noble metal nitrate solution prepared in the step B to be 50-80 g/L to obtain a noble metal nitrate coating solution;

E. coating the mixed solution obtained in the step C on the conductive substrate treated in the step A, and heating the conductive substrate to 100-300 ℃ in air atmosphere for 10-50 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 400-600 ℃ for 10-50 minutes to obtain the conductive substrate with the outer surface coated with the metal oxide catalyst intermediate layer;

F. repeating the step E until the thickness of the metal oxide catalyst intermediate layer on the surface of the conductive substrate is 6-15 μm;

G. coating the noble metal nitrate coating solution obtained in the step D on the conductive substrate treated in the step F, and heating the conductive substrate to 100-200 ℃ in inert gas atmosphere for 10-30 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 350-550 ℃ for 10-30 minutes to obtain the conductive substrate with the outer surface of the metal oxide catalyst intermediate layer coated with the metal monatomic catalyst surface layer;

H. and G, repeating the step until the thickness of the metal monatomic catalyst surface layer on the surface of the conductive base material is 1-4 mu m, thus obtaining the nickel-based active cathode.

As a further improvement of the present invention, the above-mentioned noble metal nitrates include ruthenium nitrate, palladium nitrate, iridium nitrate, platinum nitrate and silver nitrate.

As a further improvement of the invention, the metal oxide coating contains 78-82 mol% of noble metal element and 18-22 mol% of lanthanide element according to metal component;

the mole percentage of noble metal element in the surface layer of the metal monatomic catalyst is 78% -82%, and the mole percentage of lanthanide element is 18% -22%.

As a further improvement of the invention, in the metal oxide coating, the molar percentage of the noble metal element is 80 percent and the molar percentage of the lanthanide element is 20 percent based on the metal component;

the mole percentage of the noble metal element in the metal monatomic catalyst surface layer is 80%, and the mole percentage of the lanthanide element is 20%.

As a further improvement of the present invention, in the step E, the mixed solution obtained in the step C is coated on the conductive substrate treated in the step a, and the conductive substrate is heated to 150 ℃ to 250 ℃ for 20 minutes to 40 minutes in an air atmosphere to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 450-550 ℃ for 20-40 minutes to obtain the conductive substrate with the outer surface coated with the metal oxide catalyst intermediate layer;

step G, coating the noble metal nitrate coating solution obtained in step D on the conductive substrate treated in step F, and heating the conductive substrate to 120-180 ℃ in an inert gas atmosphere for 15-25 minutes to obtain a first heat-treated conductive substrate;

and then heating the first heat-treated conductive substrate to 400-500 ℃ for 15-25 minutes to obtain the conductive substrate with the metal monoatomic catalyst surface layer coated on the outer surface of the metal oxide catalyst intermediate layer.

As a further improvement of the present invention, in the step E, the mixed solution obtained in the step C is coated on the conductive substrate treated in the step a, and the conductive substrate is heated to 180 ℃ to 220 ℃ for 25 minutes to 35 minutes in an air atmosphere to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 480-520 ℃ for 25-35 minutes to obtain the conductive substrate with the outer surface of the conductive substrate coated with the metal oxide catalyst intermediate layer;

step G, coating the noble metal nitrate coating solution obtained in step D on the conductive substrate treated in step F, and heating the conductive substrate to 140-160 ℃ in an inert gas atmosphere for 18-22 minutes to obtain a first heat-treated conductive substrate;

and then heating the first heat-treated conductive substrate to 430-470 ℃ for 18-22 minutes to obtain the conductive substrate with the metal monatomic catalyst surface layer coated on the outer surface of the metal oxide catalyst intermediate layer.

The nickel-based active cathode is characterized in that a conductive substrate is made of a nickel screen, the outer surface of the conductive substrate of a nickel-based material is coated with a metal oxide catalyst intermediate layer, the outer surface of the metal oxide catalyst intermediate layer is coated with a metal monatomic catalyst surface layer, the atomic composition among the conductive substrate, the metal oxide catalyst intermediate layer and the metal monatomic catalyst surface layer can have certain gradient change by utilizing the heat treatment steps of E, FG and H, the gradient change can obviously slow down the heat effect among the conductive substrate, the metal oxide catalyst intermediate layer and the metal monatomic catalyst surface layer, thereby reducing the thermal stress, namely reducing the cracks generated among the conductive substrate, the metal oxide catalyst intermediate layer and the metal monatomic catalyst surface layer, and increasing the binding force among the conductive substrate, the metal oxide catalyst intermediate layer and the metal monatomic catalyst surface layer, therefore, the service life of the electrode can be obviously prolonged, and the anti-adversity and anti-current capability of the electrode can be improved.

Example 1.

The preparation method of the nickel-based active cathode comprises the following steps:

pretreatment of a conductive substrate

Firstly, using 320-mesh white corundum sand to sand a 30-mesh nickel base material wire mesh woven by nickel wires with the diameter of 0.18mm as a conductive matrix, then putting clear water and a cleaning agent into an ultrasonic cleaning instrument, heating to 50 ℃, putting the conductive matrix into the ultrasonic cleaning instrument, wherein the conductive matrix must be completely immersed into the clear water, ultrasonically cleaning for 4 hours, detecting the Al content in a surface mesh of the conductive matrix by using an X-hand-held fluorescence instrument, and removing residual sand on the surface of the surface mesh to obtain the cleaned conductive matrix.

Preparing the intermediate layer of the metal oxide catalyst

In this example, ruthenium nitrate and cerium nitrate were included, wherein the concentration of ruthenium nitrate was 100g/L, the molar percentage of ruthenium in the metal salt was 85%, and the molar percentage of cerium was 15%.

The ruthenium nitrate solution is placed on a magnetic stirrer with a heater and stirred for 10 minutes, then the cerium nitrate solution is added into the ruthenium nitrate solution and stirred for 10 minutes, and then the heating magnetic stirrer is used for heating and stirring. The solution was incubated for 100 minutes after reaching 80 ℃. The heater of the heating magnetic stirrer is turned off, and the heating magnetic stirrer is used for stirring and cooling to room temperature.

Uniformly coating the prepared nitrate metal salt solution on a conductive substrate, firstly baking for 30 minutes in an air atmosphere at a low temperature of 200 ℃, then continuously baking for 30 minutes in an air atmosphere at a high temperature of 500 ℃, carrying out thermal decomposition treatment on the nitrate metal salt, repeating the operation for 8 times to obtain a metal oxide catalyst intermediate layer with a set thickness, and detecting the content of each element in the metal oxide catalyst intermediate layer by an X-fluorescence instrument.

Preparation of metal monatomic catalyst surface layer

In the embodiment, the method comprises a platinum nitrate solution, wherein the concentration of platinum nitrate is 50g/L, a platinum nitrate metal salt solution is uniformly coated on the surface of a metal oxide catalyst intermediate layer of a conductive substrate, the surface is baked for 20 minutes in a nitrogen-containing protective atmosphere at a low temperature of 100 ℃, then the surface is continuously baked for 20 minutes in a nitrogen-containing protective atmosphere at a high temperature of 450 ℃ for thermal decomposition treatment, the operation is repeated for 4 times, a metal monoatomic catalyst surface layer with a certain thickness is obtained, the content of a coating is detected by an X-fluorometer, and whether the metal monoatomic catalyst surface layer has a predetermined component or not can be determined.

Example 2

The preparation method of the nickel-based active cathode comprises the following steps:

pretreatment of a conductive substrate

Firstly, using 320-mesh white corundum sand to sand a 30-mesh nickel base material nickel screen mesh woven by nickel wires with the diameter of 0.18mm as a conductive matrix, then putting clear water and a cleaning agent into an ultrasonic cleaning instrument, heating to 50 ℃, putting the conductive matrix into the ultrasonic cleaning instrument, wherein the conductive matrix must be completely immersed into the clear water, ultrasonically cleaning for 4 hours, detecting the Al content in a surface mesh of the conductive matrix by using an X-hand-held fluorescence instrument, and removing residual sand on the surface of the surface mesh to obtain the cleaned conductive matrix.

Preparing the intermediate layer of the metal oxide catalyst

In this example, ruthenium nitrate and cerium nitrate were included, wherein the concentration of ruthenium nitrate was 100g/L, the molar percentage of ruthenium in the metal salt was 80%, and the molar percentage of cerium was 20%.

The ruthenium nitrate solution is placed on a magnetic stirrer with a heater and stirred for 10 minutes, then the cerium nitrate solution is added into the ruthenium nitrate solution and stirred for 10 minutes, and then the heating magnetic stirrer is used for heating and stirring. The solution was incubated for 100 minutes after reaching 80 ℃. Turning off the heater of the heating magnetic stirrer, stirring and cooling to room temperature.

Uniformly coating the prepared nitrate metal salt solution on a conductive substrate, firstly burning for 30 minutes in an air atmosphere at a low temperature of 150 ℃, then continuously burning for 30 minutes in an oxygen-containing atmosphere at a high temperature of 450 ℃ for thermal decomposition treatment, repeating the operation for 8 times to obtain a metal oxide catalyst intermediate layer with a set thickness, and detecting the content of each element in the metal oxide catalyst intermediate layer by an X-fluorescence instrument.

Preparation of surface layer of monatomic catalyst

The method comprises the steps of uniformly coating a platinum nitrate metal salt solution on the surface of a metal oxide catalyst intermediate layer of a conductive substrate, baking the conductive substrate in a nitrogen-containing protective atmosphere at a low temperature of 200 ℃ for 20 minutes, continuously baking the conductive substrate in a nitrogen-containing protective atmosphere at a high temperature of 550 ℃ for 20 minutes to carry out thermal decomposition treatment, repeating the operation for 4 times to obtain a monatomic catalyst surface layer with a certain thickness, and detecting the content of each element in the monatomic catalyst surface layer through an X-fluorometer, wherein the concentration of platinum nitrate is 50 g/L.

Example 3

The preparation method of the nickel-based active cathode comprises the following steps:

pretreatment of a conductive substrate

Firstly, using 320-mesh white corundum sand to sand a 30-mesh nickel base material nickel screen mesh woven by nickel wires with the diameter of 0.18mm as a conductive matrix, then putting clear water and a cleaning agent into an ultrasonic cleaning instrument, heating to 50 ℃, putting the conductive matrix into the ultrasonic cleaning instrument, wherein the conductive matrix must be completely immersed into the clear water, ultrasonically cleaning for 4 hours, detecting the Al content in a surface mesh of the conductive matrix by using an X-hand-held fluorescence instrument, and removing residual sand on the surface of the surface mesh to obtain the cleaned conductive matrix.

Preparation of intermediate layer of metal oxide catalyst

In this embodiment, the catalyst contains ruthenium nitrate and cerium nitrate, wherein the concentration of ruthenium nitrate is 100g/L, and the molar percentage of the metal salt is ruthenium: cerium 75%: 25 percent.

The ruthenium nitrate solution is placed on a magnetic stirrer with a heater and stirred for 10 minutes, then the cerium nitrate solution is added into the ruthenium nitrate solution and stirred for 10 minutes, and then the heating magnetic stirrer is used for heating and stirring. The solution was incubated for 100 minutes after reaching 80 ℃. Turning off the heater of the heating magnetic stirrer, stirring and cooling to room temperature.

Uniformly coating the prepared nitric acid metal salt solution on a conductive substrate, baking for 30 minutes in air atmosphere at a low temperature of 200 ℃, then continuously baking for 30 minutes in oxygen-containing atmosphere at a high temperature of 550 ℃ for thermal decomposition treatment, repeating the operation for 8 times to obtain a metal oxide catalyst intermediate layer with a certain thickness, and detecting the content of the coating by an X-ray fluorescence instrument.

Preparation of surface layer of single-atom catalyst

In the embodiment, the method comprises the steps of uniformly coating a platinum nitrate metal salt solution on a metal oxide catalyst intermediate layer of a conductive substrate, baking the platinum nitrate metal salt solution for 20 minutes in a nitrogen-containing protective atmosphere at a low temperature of 200 ℃ and then baking the platinum nitrate metal salt solution for 20 minutes in a nitrogen-containing protective atmosphere at a high temperature of 500 ℃, repeating the operation for 4 times to obtain the metal oxide catalyst intermediate layer with a certain thickness, and detecting the content of the coating through an X-ray fluorescence instrument, wherein the concentration of platinum nitrate is 50 g/L.

Comparative example 1

The nickel-based active cathode of the present comparative example and the preparation method thereof were as follows:

pretreatment of a conductive substrate

The pretreatment of the substrate was the same as in example 1.

Preparation of metal oxide catalyst

The comparative example contains ruthenium nitrate and cerium nitrate, wherein the concentration of ruthenium nitrate is 100g/L, and the molar percentage of metal salt is ruthenium: cerium 85%: 15 percent.

The ruthenium nitrate solution is placed on a magnetic stirrer with a heater and stirred for 10 minutes, then the cerium nitrate solution is added into the ruthenium nitrate solution and stirred for 10 minutes, and then the heating magnetic stirrer is used for heating and stirring. The solution was incubated for 100 minutes after reaching 80 ℃. Turning off the heater of the heating magnetic stirrer, stirring and cooling to room temperature.

Uniformly coating the prepared nitrate metal salt solution on a conductive substrate, baking for 30 minutes in an air atmosphere at a low temperature of 200 ℃, then continuously baking for 30 minutes in an air atmosphere at a high temperature of 500 ℃ for thermal decomposition treatment, repeating the operation for 12 times to obtain a metal oxide catalyst intermediate layer with a certain thickness, and detecting the content of the coating through an X-ray fluorescence instrument.

Comparative example 2

The nickel-based active cathode of the present comparative example and the preparation method thereof were as follows:

pretreatment of conductive matrix

The pretreatment of the substrate was the same as in example 1.

Preparing the intermediate layer of the metal oxide catalyst

The comparative example contains ruthenium nitrate and cerium nitrate, wherein the concentration of ruthenium nitrate is 100g/L, and the molar percentage of metal salt is ruthenium: cerium 80%: 20 percent.

The ruthenium nitrate solution is placed on a magnetic stirrer with a heater and stirred for 10 minutes, then the cerium nitrate solution is added into the ruthenium nitrate solution and stirred for 10 minutes, and then the heating magnetic stirrer is used for heating and stirring. The solution was incubated for 100 minutes after reaching 80 ℃. The heater of the heating magnetic stirrer is turned off, and the heating magnetic stirrer is used for stirring and cooling to room temperature.

Uniformly coating the prepared nitrate metal salt solution on a conductive substrate, baking for 30 minutes in air atmosphere at low temperature of 150 ℃, then continuously baking for 30 minutes in air-containing atmosphere at high temperature of 450 ℃ for thermal decomposition treatment, repeating the operation for 12 times to obtain a metal oxide catalyst intermediate layer with a certain thickness, and detecting the content of the coating by an X-ray fluorescence instrument.

Preparation of the surface layer of the catalyst

The method comprises the steps of uniformly coating a platinum nitrate metal salt solution on a metal oxide catalyst intermediate layer of a conductive substrate, baking the platinum nitrate metal salt solution for 20 minutes in an air atmosphere at a low temperature of 200 ℃ and then continuously baking the platinum nitrate metal salt solution for 20 minutes in an air atmosphere at a high temperature of 450 ℃ to carry out thermal decomposition treatment, repeating the operation for 4 times to obtain the metal oxide catalyst intermediate layer with a certain thickness, and detecting the content of a coating through an X-fluorometer.

Comparative example 3

The nickel-based active cathode of the present comparative example and the preparation method thereof were as follows:

pretreatment of a conductive substrate

The pretreatment of the substrate was the same as in example 1.

Preparing the intermediate layer of the metal oxide catalyst

The comparative example contains ruthenium nitrate and cerium nitrate, wherein the concentration of ruthenium nitrate is 100g/L, and the molar percentage of metal salt is ruthenium: cerium 75%: 25 percent.

The ruthenium nitrate solution is placed on a magnetic stirrer with a heater and stirred for 10 minutes, then the cerium nitrate solution is added into the ruthenium nitrate solution and stirred for 10 minutes, and then the heating magnetic stirrer is used for heating and stirring. The solution was incubated for 100 minutes after reaching 80 ℃. Turning off the heater of the heating magnetic stirrer, stirring and cooling to room temperature.

Uniformly coating the prepared nitrate metal salt solution on a conductive substrate, baking for 30 minutes in an air atmosphere at a low temperature of 200 ℃, then continuously baking for 30 minutes in an air atmosphere at a high temperature of 500 ℃ for thermal decomposition treatment, repeating the operation for 12 times to obtain a metal oxide catalyst intermediate layer with a certain thickness, and detecting the content of the coating through an X-ray fluorescence instrument.

Preparation of the surface layer of the catalyst

The method comprises the steps of uniformly coating a chloroplatinic acid solution, wherein the concentration of platinum is 50g/L, the concentration of hydrochloric acid is 70g/L, baking the chloroplatinic acid solution on a metal oxide catalyst intermediate layer of a conductive substrate in a nitrogen protection atmosphere at a low temperature of 200 ℃ for 20 minutes, then continuously baking the chloroplatinic acid solution in a nitrogen protection atmosphere at a high temperature of 500 ℃ for 20 minutes to carry out thermal decomposition treatment, and repeating the operation for 4 times to obtain a precious metal oxide catalyst surface layer with a certain thickness.

Comparative example 4

The nickel-based active cathode of the present comparative example and the preparation method thereof were as follows:

pretreatment of a conductive substrate

The substrate was pretreated as in example 1.

Preparing the intermediate layer of the metal oxide catalyst

The comparative example contains ruthenium nitrate and cerium nitrate, wherein the concentration of ruthenium nitrate is 100g/L, and the molar percentage of metal salt is ruthenium: cerium 75%: 25 percent.

The ruthenium nitrate solution is placed on a magnetic stirrer with a heater and stirred for 10 minutes, then the cerium nitrate solution is added into the ruthenium nitrate solution and stirred for 10 minutes, and then the heating magnetic stirrer is used for heating and stirring. The solution was incubated for 100 minutes after reaching 80 ℃. Turning off the heater of the heating magnetic stirrer, stirring and cooling to room temperature.

Uniformly coating the prepared nitrate metal salt solution on a conductive substrate, baking for 30 minutes in an air atmosphere at a low temperature of 200 ℃, then continuously baking for 30 minutes in an air atmosphere at a high temperature of 500 ℃ for thermal decomposition treatment, repeating the operation for 12 times to obtain a metal oxide catalyst intermediate layer with a certain thickness, and detecting the content of the coating through an X-ray fluorescence instrument.

Preparation of the surface layer of the catalyst

The method comprises the steps of uniformly coating a platinum nitrate metal salt solution on a metal oxide catalyst intermediate layer of a conductive substrate, baking the platinum nitrate metal salt solution for 20 minutes in an air atmosphere at a low temperature of 200 ℃ and then continuously baking the platinum nitrate metal salt solution for 20 minutes in an air atmosphere at a high temperature of 500 ℃ to carry out thermal decomposition treatment, repeating the operation for 4 times to obtain a metal oxide catalyst intermediate layer with a certain thickness, and then keeping the metal oxide catalyst intermediate layer for 4 hours in an argon atmosphere at a temperature of 500 ℃ to reduce platinum oxide into a monoatomic structure. The coating content is detected by an X-ray fluorometer, and the method can determine that the coating has a predetermined composition.

Fig. 1b is a surface topography of a nickel-based active cathode prepared in example 1 of the present invention, and fig. 1a is a surface topography of a comparative example 1, as can be seen by comparison, the comparative example 1 is a nickel-based single catalyst coated electrode, the crystal grains on the surface of the electrode are different in size, the crystal grains are not uniformly dispersed, and the gaps among the crystal grains are large, so that the electrode is likely to enter a base material to cause corrosion when contacting an acidic substance, thereby causing the electrode coating to fall off; fig. 1b shows the composite coated electrode of the nickel-based active cathode in example 1, wherein the crystalline distribution on the surface of the electrode is compact, the gaps between the crystalline particles are small, and compared with the crystalline particles of a single coated electrode, the crystalline particle surfaces of the composite coated electrode are uniformly distributed with fine nanorods of T oxide.

FIG. 2b is a cross-sectional view of the nickel-based active cathode prepared in example 2 of the present invention, and FIG. 2a is a cross-sectional view of comparative example 2, and it can be seen from FIG. 2a that the air-burned catalyst layer of comparative example 2 is relatively loose and has poor bonding force with the nickel substrate; in the embodiment 2, the composite coating electrode catalyst layer has uniform thickness, the bonding force between the surface catalyst layer and the nickel substrate is good, and the stress resistance and the reverse current resistance of the electrode are improved.

The cathodes fabricated in examples and comparative examples were subjected to performance tests

1. The hydrogen evolution potential detection is carried out in a sodium hydroxide solution with the electrolyte of 32 percent by mass at the temperature of 90 ℃, and the result is as follows:

	4kA/m 2 hydrogen evolution potential (vs. sce)
		Example 1	1.198
Example 2	1.196
		Example 3	1.195
Comparative example 1	1.225
		Comparative example 2	1.211
Comparative example 3	1.215
		Comparative example 4	1.201

It can be seen from the table that the cathodic hydrogen evolution potential in each example is lower, much lower than the single coating electrode potential of comparative example 1. The potential of the composite electrode baked in the air atmosphere in comparison with that in comparative example 2 is also lowered. The phase potential of the monatomic catalyst layer prepared from chloroplatinic acid in comparative example 3 was lower than that of the composite electrode after argon treatment in comparative example 4 (see fig. 3).

2. And (3) an intensified reverse current test, namely continuously carrying out multiple intensified reverse current acceleration tests by electrolyzing in a sodium hydroxide solution with the electrolyte of which the mass fraction is 32%, and measuring the residual quantity of the coating. Fig. 4 is a graph comparing the residual quantity of Ru in the coating against the electric resistance, and after a plurality of cycles, the residual quantity of the composite coated electrode in the example is significantly higher than that of the electrode with a single coating in comparative example 1, and the composite coated electrode baked in the air atmosphere in comparative example 2 also has a certain electric resistance against reverse current, but slightly worse than that of the electrode in the example. Comparative example 3 the composite electrode manufactured by taking chloroplatinic acid as the raw material has the coating residual quantity which is sharply reduced along with the increase of the reverse electricity period, and the anti-reverse electricity capability is not strong. Although the composite electrode in the comparative example 4 is treated by argon, the platinum element is reduced from an oxidation state to a platinum simple substance, but part of ruthenium oxide is reduced to metallic ruthenium, so that the bonding force of the coating is reduced, and the anti-reverse current resistance of the electrode is affected, which shows that the composite coating electrode in the invention has stronger anti-reverse current resistance.

Fig. 5 is a graph comparing the resistance to reverse electric energy with the residual amount of Pt in the coating, and it can be seen from fig. 5 that the residual amount of Pt in the composite coated electrode in each example is relatively high after a plurality of cycles. The invention can effectively inhibit the damage of the reverse current to the cathode surface net.

The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.

Claims (10)

1. The nickel-based active cathode is characterized by comprising a conductive matrix of a nickel base material, wherein the conductive matrix is made of a nickel screen, the outer surface of the conductive matrix is coated with a metal oxide catalyst intermediate layer, and the outer surface of the metal oxide catalyst intermediate layer is coated with a metal monatomic catalyst surface layer;

the metal oxide catalyst intermediate layer is composed of oxides of noble metal elements and oxides of lanthanide elements, the thickness of the metal oxide catalyst intermediate layer is 6-15 μm, and the mole percentage of the noble metal elements in the metal oxide coating is 75-85% and the mole percentage of the lanthanide elements in the metal oxide coating is 15-25%;

the surface layer of the metal monatomic catalyst is composed of noble metal elements, and the thickness of the surface layer of the metal monatomic catalyst is 1-4 μm;

the nickel-based active cathode is prepared by the following steps:

A. preparing a conductive matrix of a nickel substrate by using a nickel wire mesh, cleaning the conductive matrix, removing dirt on the surface of the conductive matrix, and roughening the surface of the conductive matrix;

B. preparing soluble nitrate of lanthanide and soluble nitrate of noble metal element, respectively dissolving the soluble nitrate of lanthanide and the soluble nitrate of noble metal element in water to obtain soluble nitrate solution of lanthanide and noble metal nitrate solution for later use;

C. b, mixing the lanthanide soluble nitrate solution and the noble metal nitrate solution obtained in the step B according to the proportion that the mole percentage of the noble metal element is 75-85 percent and the mole percentage of the lanthanide is 15-25 percent, wherein the concentration of the noble metal in the mixed solution is 100-120 g/L, and obtaining the mixed solution;

D. regulating and controlling the concentration of the noble metal in the noble metal nitrate solution prepared in the step B to be 50-80 g/L to obtain a noble metal nitrate coating solution;

E. coating the mixed solution obtained in the step C on the conductive substrate treated in the step A, and heating the conductive substrate to 100-300 ℃ in air atmosphere for 10-50 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 400-600 ℃ for 10-50 minutes to obtain the conductive substrate with the outer surface coated with the metal oxide catalyst intermediate layer;

F. repeating the step E until the thickness of the metal oxide catalyst intermediate layer on the surface of the conductive substrate is 6-15 μm;

G. coating the noble metal nitrate coating solution obtained in the step D on the conductive substrate treated in the step F, and heating the conductive substrate to 100-200 ℃ in an inert gas atmosphere for 10-30 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 350-550 ℃ for 10-30 minutes to obtain the conductive substrate with the outer surface of the metal oxide catalyst intermediate layer coated with the metal monatomic catalyst surface layer;

H. and G, repeating the step until the thickness of the metal monatomic catalyst surface layer on the surface of the conductive base material is 1-4 mu m, thus obtaining the nickel-based active cathode.

2. The nickel-based active cathode according to claim 1, wherein the noble metal nitrates comprise ruthenium nitrate, palladium nitrate, iridium nitrate, platinum nitrate and silver nitrate, and the metal oxide coating comprises 78 to 82 mole percent of noble metal elements and 18 to 22 mole percent of lanthanides, based on the metal content;

the mole percentage of noble metal element in the surface layer of the metal monatomic catalyst is 78% -82%, and the mole percentage of lanthanide element is 18% -22%.

3. The nickel-based active cathode according to claim 2, characterized in that the metal oxide coating comprises, in terms of metal component, 80 mole percent of noble metal elements and 20 mole percent of lanthanides;

the mole percentage of the noble metal element in the metal monatomic catalyst surface layer is 80%, and the mole percentage of the lanthanide element is 20%.

4. The nickel-based active cathode according to claim 1, 2 or 3, wherein the mixed solution obtained in step E is applied to the conductive substrate treated in step A, and the conductive substrate is heated to 150 ℃ to 250 ℃ for 20 minutes to 40 minutes in an air atmosphere to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 450-550 ℃ for 20-40 minutes to obtain the conductive substrate with the outer surface coated with the metal oxide catalyst intermediate layer;

step G, coating the noble metal nitrate coating solution obtained in step D on the conductive substrate treated in step F, and heating the conductive substrate to 120-180 ℃ in an inert gas atmosphere for 15-25 minutes to obtain a first heat-treated conductive substrate;

and then heating the first heat-treated conductive substrate to 400-500 ℃ for 15-25 minutes to obtain the conductive substrate with the metal monoatomic catalyst surface layer coated on the outer surface of the metal oxide catalyst intermediate layer.

5. The preparation method of the nickel-based active cathode is characterized by comprising the following steps of:

A. preparing a conductive matrix of a nickel substrate by using a nickel wire mesh, cleaning the conductive matrix, removing dirt on the surface of the conductive matrix, and roughening the surface of the conductive matrix;

B. preparing soluble nitrate of lanthanide and soluble nitrate of noble metal element, respectively dissolving the soluble nitrate of lanthanide and the soluble nitrate of noble metal element in water to obtain soluble nitrate solution of lanthanide and noble metal nitrate solution for later use;

C. b, mixing the lanthanide soluble nitrate solution and the noble metal nitrate solution obtained in the step B according to the proportion that the mole percentage of the noble metal element is 75-85 percent and the mole percentage of the lanthanide is 15-25 percent, wherein the concentration of the noble metal in the mixed solution is 100-120 g/L, and obtaining the mixed solution;

D. regulating and controlling the concentration of the noble metal in the noble metal nitrate solution prepared in the step B to be 50-80 g/L to obtain a noble metal nitrate coating solution;

E. coating the mixed solution obtained in the step C on the conductive substrate treated in the step A, and heating the conductive substrate to 100-300 ℃ in air atmosphere for 10-50 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive base material to 400-600 ℃ for 10-50 minutes to obtain the conductive base material of which the outer surface is coated with the metal oxide catalyst intermediate layer;

F. repeating the step E until the thickness of the metal oxide catalyst intermediate layer on the surface of the conductive substrate is 6-15 μm;

G. coating the noble metal nitrate coating solution obtained in the step D on the conductive substrate treated in the step F, and heating the conductive substrate to 100-200 ℃ in an inert gas atmosphere for 10-30 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 350-550 ℃ for 10-30 minutes to obtain the conductive substrate with the surface layer of the metal monatomic catalyst coated on the outer surface of the metal oxide catalyst intermediate layer;

H. and G, repeating the step until the thickness of the metal monatomic catalyst surface layer on the surface of the conductive base material is 1-4 mu m, thus obtaining the nickel-based active cathode.

6. The method for preparing a nickel-based active cathode according to claim 5, characterized in that the noble metal nitrates comprise ruthenium nitrate, palladium nitrate, iridium nitrate, platinum nitrate and silver nitrate.

7. The method of claim 6, wherein the metal oxide coating comprises from about 78 mole percent to about 82 mole percent noble metal elements and from about 18 mole percent to about 22 mole percent lanthanide elements, based on the metal content;

the mole percentage of noble metal element in the surface layer of the metal single-atom catalyst is 78% -82%, and the mole percentage of lanthanide element is 18% -22%.

8. The nickel-based active cathode according to claim 7, characterized in that the metal oxide coating comprises, in terms of metal component, 80 mole percent of noble metal elements and 20 mole percent of lanthanides;

the mole percentage of the noble metal element in the metal monatomic catalyst surface layer is 80%, and the mole percentage of the lanthanide element is 20%.

9. The nickel-based active cathode according to any one of claims 5 to 8, wherein the mixed solution obtained in step E is applied to the conductive substrate treated in step a, and the conductive substrate is heated to 150 ℃ to 250 ℃ for 20 minutes to 40 minutes in an air atmosphere to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 450-550 ℃ for 20-40 minutes to obtain the conductive substrate with the outer surface coated with the metal oxide catalyst intermediate layer;

step G, coating the noble metal nitrate coating solution obtained in step D on the conductive substrate treated in step F, and heating the conductive substrate to 120-180 ℃ in an inert gas atmosphere for 15-25 minutes to obtain a first heat-treated conductive substrate;

and then heating the first heat-treated conductive substrate to 400-500 ℃ for 15-25 minutes to obtain the conductive substrate with the metal monoatomic catalyst surface layer coated on the outer surface of the metal oxide catalyst intermediate layer.

10. The nickel-based active cathode according to claim 9, wherein the step E comprises applying the mixed solution obtained in step C to the conductive substrate treated in step a, and heating the conductive substrate to a temperature of 180 ℃ to 220 ℃ in an air atmosphere for 25 minutes to 35 minutes to obtain a first heat-treated conductive substrate;

then heating the first heat-treated conductive substrate to 480-520 ℃ for 25-35 minutes to obtain the conductive substrate with the outer surface of the conductive substrate coated with the metal oxide catalyst intermediate layer;

step G, coating the noble metal nitrate coating solution obtained in step D on the conductive substrate treated in step F, and heating the conductive substrate to 140-160 ℃ in an inert gas atmosphere for 18-22 minutes to obtain a first heat-treated conductive substrate;

and then heating the first heat-treated conductive substrate to 430-470 ℃ for 18-22 minutes to obtain the conductive substrate with the metal monatomic catalyst surface layer coated on the outer surface of the metal oxide catalyst intermediate layer.

Images