CN109811360B

CN109811360B - NiFeMo ternary electrolytic water electrode and preparation method thereof

Info

Publication number: CN109811360B
Application number: CN201910183487.4A
Authority: CN
Inventors: 张耕; 曹菲菲; 李勇科
Original assignee: Huazhong Agricultural University
Current assignee: Huazhong Agricultural University
Priority date: 2019-03-12
Filing date: 2019-03-12
Publication date: 2020-06-05
Anticipated expiration: 2039-03-12
Also published as: CN109811360A

Abstract

The invention discloses a NiFeMo ternary electrolytic water electrode and a preparation method thereof, wherein ferric salt, nickel salt, urea and NH are firstly used under low-temperature hydrothermal condition₄Preparing NiFe-LDH/NF by taking F as a raw material, and then carrying out low-temperature hydrothermal treatment on the NiFe-LDH/NF and a molybdenum-containing compound to obtain Ni-Fe_trace@ NFM/NF, followed by Ni-Fe_traceThe @ NFM/NF is put in a flowing reducing atmosphere for heat treatment for a certain time to obtain the final material Ni/NiFeMoO_x/NF, the process of LDH substrate reduction into Ni nanoparticles, with NiFe-MoO formed with reduced molybdate_xCross-linking with each other to form a composite material with a hierarchical porous nanosheet structure. The hierarchical porous nanosheet structure is beneficial to bubble diffusion, and formed alloy and MoO_xThe material is crosslinked and combined with a conductive substrate to have excellent conductivity, so that the material has excellent reaction kinetics; NiFe-MoO with high hydrogen evolution activity_xThe Ni nano-particles with high oxygen evolution activity endow the material with excellent hydrogen evolution and oxygen evolution performances, and further obtain the performance of catalyzing the full electrolysis water with application prospect.

Description

NiFeMo ternary electrolytic water electrode and preparation method thereof

Technical Field

The invention relates to an electrolytic water electrode and a preparation method thereof, in particular to a NiFeMo ternary electrolytic water electrode and a preparation method thereof.

Background

The increasing exhaustion of fossil energy and the resulting environmental deterioration issues have made the search for new energy generation urgent. Hydrogen energy is one of the most promising energy sources, and its utilization forms are various and environmentally friendly, so it is a hot spot or even a long-term plan of competitive research in various countries. The preparation of hydrogen is the first prerequisite for hydrogen energy utilization, but at present, the main source of hydrogen is still fossil fuel, so the development of a renewable hydrogen production mode has important significance. The hydrogen production by electrolyzing water has the advantages of high conversion efficiency, simple process and high purity of the produced hydrogen, and is considered to be an ideal hydrogen production method. The hydrogen production by electrolysis of water can be carried out in an acidic or alkaline electrolyte. The noble metals Pt and IrO are required to be used under the acidic condition₂/RuO₂As a catalyst, the limited reserves and high price of precious metals make the electrolysis of water under acidic conditions unfeasible on a large scale. At present, the electrolytic water under alkaline condition mainly uses metallic nickel and stainless steel as electrodesHowever, the existence of high overpotential in the electrolysis process results in low energy utilization rate and undesirable economic benefit. Therefore, the development of a low-price and high-efficiency non-noble metal hydrogen and oxygen evolution catalyst becomes the key point of the large-scale application of the electrolyzed water.

The transition metal has excellent hydrogen evolution and oxygen evolution catalytic performance because the electronic structure of the transition metal is close to that of the noble metal. However, the performance of the transition metal catalyst prepared at present cannot be compared favorably with that of noble metals, in addition, most of the catalysts only have excellent performance of hydrogen or oxygen evolution single catalysis, and the integral electrocatalytic hydrolysis performance still has a larger gap with the combination of the noble metals. Therefore, the development of the bifunctional water electrolysis catalyst with excellent hydrogen and oxygen evolution performances is significant. Long-term research shows that the nickel-based nano material has excellent Oxygen Evolution (OER) catalytic performance, but the Hydrogen Evolution (HER) performance is not ideal. Meanwhile, recent research shows that the Ni-Mo-O compound (Nature Communications 2017,15437.Advanced Materials 2017,1703311) nano material has hydrogen evolution performance which is comparable to that of Pt, but the oxygen evolution performance is low. It is still a challenge to develop a dual-function water electrolysis material combining two types of materials with high hydrogen and oxygen evolution activities.

The catalytic material directly grows on the three-dimensional conductive substrate, so that the conductivity of the material can be greatly improved, and the rapid diffusion of bubbles is facilitated, thereby being beneficial to improving the catalytic performance of the material. In addition, the materials are mutually crosslinked to generate a layered multi-level nanosheet structure, so that the conductivity of the materials is improved, and meanwhile, active sites of the materials are further exposed.

Disclosure of Invention

According to the defects of the prior art, the invention provides the NiFeMo ternary electrolytic water electrode and the preparation method thereof, which have the functions of hydrogen evolution and oxygen evolution double catalysis, and have the characteristics of low price, high efficiency, non-noble metal and low cost.

The invention relates to a NiFeMo ternary electrolytic water electrode, which is characterized in that: the NiFeMo ternary electrolytic water electrode is NiFe-MoO_xCombining a composite of Ni nano particles and mutually crosslinking the composite to form a nano sheet with a hierarchical porous structure and growing the nano sheet on the three-dimensional conductive substrate foamed nickel,the NiFe-MoO_xNiFe-doped non-integral-ratio MoO being amorphous_x。

The invention relates to a preparation method of a NiFeMo ternary electrolytic water electrode, which comprises the following specific preparation steps:

(1) mixing iron salt, nickel salt and NH₄F and urea are dissolved in deionized water, and after complete dissolution, foam nickel is added and hydrothermal is carried out, and after cooling and washing, the foam nickel-loaded NiFe double metal hydroxide, namely NiFe-LDH/NF, is obtained;

(2) dissolving molybdenum-containing compound in deionized water, adding NiFe-LDH/NF, hydrothermal treating, cooling, and cleaning to obtain Ni-Fe_trace@NFM/NF；

(3) The Ni-Fe obtained in the step (2) is added_trace@ NFM/NF is placed in flowing reducing atmosphere for heat treatment to finally obtain Ni/NiFeMoO_x/NF。

Wherein, the preferred scheme is as follows:

in the step (1), the concentration of the iron salt is 5 mmol/L-20 mmol/L, the concentration ratio of the iron salt to the nickel salt is 1: 1-20, the concentration of the urea is 100-400 mmol/L, the concentration of the ammonium fluoride is 30-300 mmol/L, the iron salt is one of ferric nitrate, ferric chloride or ferric sulfate, and the nickel salt is one of nickel nitrate, nickel acetate, nickel chloride or nickel sulfate.

The hydrothermal time in the step (1) is 2-48 h, and the hydrothermal temperature is 100-200 ℃.

The mass ratio of the foamed nickel to the deionized water in the step (1) is 1: 10-1: 400.

The amount concentration of the molybdenum-containing compound in the step (2) is 5 mmol/L-40 mmol/L, and the molybdenum-containing compound is one of ammonium heptamolybdate, ammonium molybdate or sodium molybdate.

The hydrothermal time in the step (2) is 2-36 h, and the hydrothermal temperature is 100-200 ℃.

In the step (3), the reducing atmosphere is one of hydrogen or carbon monoxide, when hydrogen is used as the reducing atmosphere, argon is required to be introduced as a protective gas, and the proportion of the hydrogen to the argon is usually 5% V_H2/95％V_Ar。

The heat treatment in the step (3) is carried out for 1 to 24 hours at the temperature of between 300 and 800 ℃.

The preparation method of the invention is that firstly under the low-temperature hydrothermal condition, ferric salt, nickel salt, urea and NH are added₄Preparing NiFe-LDH/NF by taking F as a raw material, and then carrying out low-temperature hydrothermal treatment on the NiFe-LDH/NF and a molybdenum-containing compound to obtain Ni-Fe_trace@ NFM/NF, followed by Ni-Fe_traceThe @ NFM/NF is put in a flowing reducing atmosphere for heat treatment for a certain time to obtain the final material Ni/NiFeMoO_x/NF, the process of LDH substrate reduction into Ni nanoparticles, with NiFe-MoO formed with reduced molybdate_xCross-linking with each other to form a composite material with a hierarchical porous nanosheet structure. The hierarchical porous nanosheet structure is beneficial to bubble diffusion, and formed alloy and MoO_xThe material is crosslinked and combined with a conductive substrate to have excellent conductivity, so that the material has excellent reaction kinetics; NiFe-MoO with high hydrogen evolution activity_xThe Ni nano-particles with high oxygen evolution activity endow the material with excellent hydrogen evolution and oxygen evolution performances, and further obtain the performance of catalyzing the full electrolysis water with application prospect.

The invention has the following advantages:

1) the metal salt, urea and NH related to the invention₄F. The solvent and the reducing atmosphere are cheap and easy to obtain, and the preparation cost is low;

2) the hydrothermal reaction temperature of the step (1) and the step (2) is low, and the large-scale application prospect is good;

3) all materials of the invention have simple treatment process, do not relate to the use of strong corrosivity, strong oxidizing property and extremely toxic substance, the feasibility is high;

4) the NiFeMo ternary electrolytic water electrode prepared by the invention is prepared by mixing NiFe-MoO with high hydrogen evolution activity_xCombined with Ni nano-particles with high oxygen evolution activity, solves the long-standing problem that one material only has relatively good catalytic performance. Composite and porous structure of high-activity substance and good conductivity of Ni/NiFeMoO_xThe NF obtains excellent hydrogen evolution and oxygen evolution and good electrolytic water catalytic performance.

Drawings

FIG. 1(a) shows an NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 3_xSEM picture of/NF;

FIG. 1(b) shows an NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 3_xTEM image of/NF;

FIG. 1(c) shows an NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 3_xHRTEM image of/NF, inset is selected area electron diffraction pattern;

FIG. 1(d) shows an NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 3_xThe mercury intrusion pore size distribution diagram of/NF;

FIG. 1(e) shows an NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 3_xBET test pattern of/NF, inset is the corresponding pore size distribution diagram;

FIG. 1(f) shows an NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 3_xXRD ray diffraction data pattern of/NF;

FIG. 2(a) shows an NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 3_x Mo 3d XPS plot of/NF;

FIG. 2(b) shows the NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 3_xO1 sXPS plot of/NF;

FIG. 2(c) shows the NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 3_xEXAFS plot of/NF;

FIG. 2(d) shows the NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 3_xXANES diagram of/NF;

FIG. 2(e1) shows the NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 3_xSEM picture of/NF;

FIG. 2(e2) is an EDS map within the rectangular region of FIG. (e 1);

FIG. 3(a) shows the NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 4_xHER polarization curve of electrochemical performance test of NF in 1M potassium hydroxide aqueous solution;

FIG. 3(b) shows the NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 4_xHER stability test chart of electrochemical performance test of NF in 1M potassium hydroxide aqueous solution;

FIG. 3(c) shows the NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 4_xOER polarization curve of electrochemical performance test of NF in 1M potassium hydroxide aqueous solution;

FIG. 3(d) shows the NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 4_xOER stability test pattern of electrochemical performance test of NF in 1M potassium hydroxide aqueous solution;

FIG. 3(e) shows the NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 4_xWhen the/NF is assembled into a full water electrolysis device, the industrial grade is 500mA/cm²A test chart continuously working for more than 200 hours under high current density;

FIG. 4(a) shows a NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 11_xSEM picture I of HER electrode after complete electrolysis of NF in 1M potassium hydroxide water solution for 24 h;

FIG. 4(b) shows a NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 11_xSEM picture II of HER electrode after complete electrolysis of NF in 1M potassium hydroxide water solution for 24 h;

FIG. 4(c) shows a NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 11_xSEM picture I of OER electrode after complete electrolysis of NF in 1M potassium hydroxide water solution for 24 h;

FIG. 4(d) shows a NiFeMo ternary electrolytic water electrode Ni/NiFeMoO obtained in example 11_xSEM image II of OER electrode after 24h of full electrolysis of NF in 1M aqueous potassium hydroxide.

Detailed Description

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

Example 1:

weighing 0.24g of urea, 0.05g of ammonium fluoride, 0.4mmol of ferric nitrate nonahydrate and 8mmol of nickel nitrate hexahydrate, dissolving in 40ml of deionized water, stirring and dissolving, transferring into a 50ml reaction kettle, adding a piece of 2g of nickel foam cleaned by 3mol of hydrochloric acid, and carrying out hydrothermal treatment in an oven at 100 ℃ for 2 hours. And after the reaction is finished, taking out the foamed nickel, washing to obtain a foamed nickel material with the surface covered with a yellow-green material, putting the foamed nickel material into 40ml of ammonium heptamolybdate water solution with the mass concentration of 20mmol/L, and transferring the foamed nickel material into a 50ml reaction kettle to carry out hydrothermal reaction at 120 ℃ for 10 hours. And after the reaction is finished, cleaning to obtain a foamed nickel material with the brick red material covered on the surface, drying, putting into a quartz furnace tube of the tube furnace, maintaining the atmosphere of carbon monoxide, heating to 350 ℃ at the speed of 5 ℃/min, and keeping for 2h to change the brick red color of the material into black color, thereby obtaining the NiFeMo ternary electrolytic water electrode.

Example 2:

weighing 0.6g of urea, 0.2g of ammonium fluoride, 8mmol of ferric nitrate nonahydrate and 8mmol of nickel nitrate hexahydrate, dissolving in 40ml of deionized water, stirring and dissolving, transferring into a 50ml reaction kettle, adding a piece of 0.1g of nickel foam cleaned by 3mol of hydrochloric acid, and carrying out hydrothermal reaction in an oven at 100 ℃ for 20 hours. And after the reaction is finished, taking out the foamed nickel, washing to obtain a foamed nickel material with the surface covered with a yellow-green material, putting the foamed nickel material into 40ml of ammonium heptamolybdate water solution with the mass concentration of 40mmol/L, and transferring the foamed nickel material into a 50ml reaction kettle for hydrothermal treatment at 150 ℃ for 20 h. After the completion of the cleaning, the foamed nickel material with brick red material covered on the surface is obtained, dried and put into a quartz furnace tube of a tube furnace, and the temperature is maintained at 5 percent (5 percent V)_H2/95％V_Ar) And (3) heating to 300 ℃ at the speed of 5 ℃/min in the mixed atmosphere of hydrogen and argon, and keeping for 10 hours, wherein the material is changed from brick red to black, thus obtaining the NiFeMo ternary electrolytic water electrode.

Example 3:

weighing 0.6g of urea, 0.2g of ammonium fluoride, 0.4mmol of ferric nitrate nonahydrate and 5mmol of nickel nitrate hexahydrate, dissolving in 40ml of deionized water, stirring and dissolving, transferring into a 50ml reaction kettle, adding a piece of 0.6g of nickel foam cleaned by 3mol of hydrochloric acid, and carrying out hydrothermal reaction in an oven at 120 ℃ for 12 hours. And after the reaction is finished, taking out the foamed nickel, washing to obtain a foamed nickel material with the surface covered with a yellow-green material, putting the foamed nickel material into 40ml of ammonium heptamolybdate water solution with the mass concentration of 10mmol/L, and transferring the foamed nickel material into a 50ml reaction kettle to carry out hydrothermal reaction at 120 ℃ for 10 hours. After the completion of the cleaning, the foamed nickel material with brick red material covered on the surface is obtained, dried and put into a quartz furnace tube of a tube furnace, and the temperature is maintained at 5 percent (5 percent V)_H2/95％V_Ar) And (3) heating to 400 ℃ at the speed of 5 ℃/min in the mixed atmosphere of hydrogen and argon, and keeping for 2 hours, wherein the material is changed from brick red to black, thus obtaining the NiFeMo ternary electrolytic water electrode.

It can be seen from fig. 1(a) that the material is a nanosheet structure arranged on the nickel foam, fig. 1(b) that the material has a porous structure, fig. 1(d) and fig. 1(e) that the material has a hierarchical porous structure of micron-submicron-mesopores, fig. 1(f) that a phase of metallic Ni appears in the material, and no peaks are clearly shown at other positions indicating the presence of an amorphous structure in the material, which corresponds to the lattice of the Ni (111) crystal plane appearing in fig. 1(c) and the result of selective electron diffraction in the inset of fig. 1 (c).

FIG. 2(a) shows Mo as Mo in the material⁶⁺And Mo⁵⁺The form exists, oxygen vacancy exists in the material of FIG. 2(b), and similar MoO appears obviously in FIG. 2(c)₃The absorption edge of the co-edge Mo-Mo hexahedron is simultaneously appeared, which indicates that Mo has non-integral ratio of oxygen vacancy and MoO_xIn which MoO is present_xThe octahedral structure is formed in a Mo-Mo bond edge sharing mode, the disappearance of the edge front peak at 22008eV of the material in FIG. 2(d) shows the change of the crystal structure of the material, and the forward movement of the absorption edge compared with Ni-Fe LDH @ NFM also shows that the Mo element of the material is reduced and the valence state is reduced. Fig. 2(e1-e2) and table 1 show that the group elements of the material are mainly Ni, Mo, O, and in addition, a small amount of Fe is doped in the material.

Table 1: table of contents of respective elements in rectangular region of FIG. 2(e1)

Elt	Line	Atomic％	Conc	Units
						C	Ka	19.789	6.020	Wt.％
O	Ka	35.896	14.546	Wt.％
						Fe	Ka	1.273	1.800	Wt.％
Ni	Ka	28.586	42.507	Wt.％
						Mo	La	14.456	35.127	Wt.％
		100.000	100.000	Wt.％	Total

Taken together, all the graphs show that the material produced is amorphous NiFe doped, low valence MoO with oxygen vacancies arranged on a nickel mesh_xA porous nanosheet array consisting of bonded Ni nanoparticles.

Example 4:

weighing 0.6g of urea, 0.2g of ammonium fluoride, 0.4mmol of ferric nitrate nonahydrate and 4mmol of nickel nitrate hexahydrate, dissolving in 40ml of deionized water, stirring and dissolving, transferring into a 50ml reaction kettle, adding a piece of 0.6g of nickel foam cleaned by 3mol of hydrochloric acid, and carrying out hydrothermal reaction in an oven at 120 ℃ for 12 hours. And after the reaction is finished, taking out the foamed nickel, washing to obtain a foamed nickel material with the surface covered with a yellow-green material, putting the foamed nickel material into 40ml of ammonium heptamolybdate water solution with the mass concentration of 40mmol/L, and transferring the foamed nickel material into a 50ml reaction kettle for hydrothermal treatment at 150 ℃ for 15 h. After the completion of the cleaning, the foamed nickel material with brick red material covered on the surface is obtained, dried and put into a quartz furnace tube of a tube furnace, and the temperature is maintained at 5 percent (5 percent V)_H2/95％V_Ar) And (3) heating to 400 ℃ at the speed of 5 ℃/min in the mixed atmosphere of hydrogen and argon, and keeping for 2 hours, wherein the material is changed from brick red to black, thus obtaining the NiFeMo ternary electrolytic water electrode.

FIG. 3(a) and FIG. 3(b) are HER polarization curve and stability test chart, respectively, which show that the catalytic performance is close to commercial noble metal catalyst Pt/C, and simultaneously, the catalyst has excellent stability performance, the performance is kept unchanged after 1000 cycles of linear cycle, and the current density is not reduced after the catalyst works at constant potential of-0.045V (vs RHE) for 24 h. FIG. 3(c) and FIG. 3(d) are OER polarization curve and stability test chart, respectively, which are far superior in catalytic performance to the commercial noble metal catalyst IrO₂Simultaneously has excellent stability, and the performance is kept unchanged after 1000 cycles of linear circulationThe current density is not reduced after the constant potential of 1.557V (vs RHE) is operated for 24 h. FIG. 3(e) shows the assembly of the electrodes into a fully electrolyzed water apparatus at a commercial scale of 500mA/cm²The voltage basically keeps unchanged when the continuous working is carried out for more than 200 hours under the high current density, and the method shows good industrial application prospect.

Example 5:

weighing 0.96g of urea, 0.4g of ammonium fluoride, 4mmol of ferric nitrate nonahydrate and 8mmol of nickel nitrate hexahydrate, dissolving in 40ml of deionized water, stirring and dissolving, transferring into a 50ml reaction kettle, adding a piece of 0.6g of nickel foam cleaned by 3mol of hydrochloric acid, and carrying out hydrothermal reaction in an oven at 160 ℃ for 24 hours. And after the reaction is finished, taking out the foamed nickel, washing to obtain a foamed nickel material with the surface covered with a yellow-green material, putting the foamed nickel material into 40ml of ammonium heptamolybdate water solution with the mass concentration of 5mmol/L, and transferring the foamed nickel material into a 50ml reaction kettle to carry out hydrothermal treatment at 200 ℃ for 3 h. And after the reaction is finished, cleaning to obtain a foamed nickel material with the brick red material covered on the surface, drying, putting into a quartz furnace tube of the tube furnace, maintaining the atmosphere of carbon monoxide, heating to 500 ℃ at the speed of 5 ℃/min, keeping for 1h, and changing the brick red color of the material into black color to obtain the NiFeMo ternary electrolytic water electrode.

Example 6:

weighing 0.5g of urea, 0.3g of ammonium fluoride, 0.8mmol of ferric nitrate nonahydrate and 8mmol of nickel nitrate hexahydrate, dissolving in 80ml of deionized water, stirring and dissolving, transferring into a 100ml reaction kettle, adding a piece of 0.8g of nickel foam cleaned by 3mol of hydrochloric acid, and carrying out hydrothermal reaction in an oven at 200 ℃ for 48 hours. And after the reaction is finished, taking out the foamed nickel, washing to obtain a foamed nickel material with the surface covered with a yellow-green material, putting the foamed nickel material into 80ml of ammonium heptamolybdate water solution with the mass concentration of 40mmol/L, and transferring the foamed nickel material into a 100ml reaction kettle for hydrothermal treatment at 100 ℃ for 36 hours. After the completion of the cleaning, the foamed nickel material with brick red material covered on the surface is obtained, dried and put into a quartz furnace tube of a tube furnace, and the temperature is maintained at 5 percent (5 percent V)_H2/95％V_Ar) And (3) heating to 700 ℃ at the speed of 5 ℃/min in the hydrogen-argon mixed atmosphere, keeping for 10 hours, and changing the brick red color of the material into black color to obtain the NiFeMo ternary electrolytic water electrode.

Example 7:

weighing 0.4g of urea, 0.1g of ammonium fluoride, 1mmol of ferric chloride hexahydrate and 8mmol of nickel sulfate hexahydrate, dissolving in 40ml of deionized water,stirring and dissolving, transferring into a 50ml reaction kettle, adding a piece of 0.6g of foamed nickel washed by 3mol of hydrochloric acid, and carrying out hydrothermal treatment for 5h at 180 ℃ in an oven. And after the reaction is finished, taking out the foamed nickel, washing to obtain a foamed nickel material with the surface covered with a yellow-green material, putting the foamed nickel material into 40ml of sodium molybdate aqueous solution with the mass concentration of 40mmol/L, and transferring the foamed nickel material into a 50ml reaction kettle to carry out hydrothermal reaction at 120 ℃ for 10 hours. After the completion of the cleaning, the foamed nickel material with brick red material covered on the surface is obtained, dried and put into a quartz furnace tube of a tube furnace, and the temperature is maintained at 5 percent (5 percent V)_H2/95％V_Ar) And (3) heating to 400 ℃ at the speed of 5 ℃/min in the hydrogen-argon mixed atmosphere, keeping for 24 hours, and changing the brick red color of the material into black color to obtain the NiFeMo ternary electrolytic water electrode.

Example 8:

weighing 0.6g of urea, 0.2g of ammonium fluoride, 2mmol of ferric chloride hexahydrate and 2mmol of nickel chloride hexahydrate in 40ml of deionized water, stirring and dissolving, transferring into a 50ml reaction kettle, adding a piece of 0.6g of foamed nickel cleaned by 3mol of hydrochloric acid, and carrying out hydrothermal reaction in an oven at 120 ℃ for 24 hours. And after the reaction is finished, taking out the foamed nickel, washing to obtain a foamed nickel material with the surface covered with a yellow-green material, putting the foamed nickel material into 40ml of ammonium heptamolybdate water solution with the mass concentration of 25mmol/L, and transferring the foamed nickel material into a 50ml reaction kettle to carry out hydrothermal reaction at 150 ℃ for 10 h. After the completion of the cleaning, the foamed nickel material with brick red material covered on the surface is obtained, dried and put into a quartz furnace tube of a tube furnace, and the temperature is maintained at 5 percent (5 percent V)_H2/95％V_Ar) And (3) heating to 400 ℃ at the speed of 5 ℃/min in the mixed atmosphere of hydrogen and argon, keeping for 15 hours, and changing the brick red color of the material into black color to obtain the NiFeMo ternary electrolytic water electrode.

Example 9:

weighing 0.6g of urea, 0.2g of ammonium fluoride, 1mmol of ferric sulfate monohydrate and 10mmol of nickel acetate tetrahydrate, dissolving in 40ml of deionized water, stirring and dissolving, transferring into a 50ml reaction kettle, adding a piece of 1g of foamed nickel cleaned by 3mol of hydrochloric acid, and carrying out hydrothermal reaction in an oven at 100 ℃ for 40 h. And after the reaction is finished, taking out the foamed nickel, washing to obtain a foamed nickel material with the surface covered with a yellow-green material, putting the foamed nickel material into 40ml of sodium molybdate aqueous solution with the amount concentration of 40mmol/L, and transferring the foamed nickel material into a 50ml reaction kettle to carry out hydrothermal reaction at 180 ℃ for 20 h. And after the reaction is finished, cleaning to obtain a foamed nickel material with the brick red material covered on the surface, drying, putting into a quartz furnace tube of the tube furnace, maintaining the atmosphere of carbon monoxide, heating to 800 ℃ at the speed of 5 ℃/min, keeping for 3h, and changing the brick red color of the material into black color to obtain the NiFeMo ternary electrolytic water electrode.

Example 10:

weighing 0.6g of urea, 0.2g of ammonium fluoride, 0.4mmol of ferric chloride hexahydrate and 8mmol of nickel chloride hexahydrate in 40ml of deionized water, stirring and dissolving, transferring into a 50ml reaction kettle, adding a piece of 1g of foamed nickel cleaned by 3mol of hydrochloric acid, and carrying out hydrothermal reaction in an oven at 120 ℃ for 12 hours. And after the reaction is finished, taking out the foamed nickel, washing to obtain a foamed nickel material with the surface covered with a yellow-green material, putting the foamed nickel material into 40ml of ammonium heptamolybdate water solution with the mass concentration of 40mmol/L, and transferring the foamed nickel material into a 50ml reaction kettle to carry out hydrothermal reaction for 10 hours at 160 ℃. After the completion of the cleaning, the foamed nickel material with brick red material covered on the surface is obtained, dried and put into a quartz furnace tube of a tube furnace, and the temperature is maintained at 5 percent (5 percent V)_H2/95％V_Ar) And (3) heating to 600 ℃ at the speed of 5 ℃/min in the mixed atmosphere of hydrogen and argon, and keeping for 2 hours, so that the material is changed from brick red to black, and the NiFeMo ternary electrolytic water electrode is obtained.

Example 11:

weighing 0.6g of urea, 0.2g of ammonium fluoride, 0.4mmol of ferric nitrate nonahydrate and 4.5mmol of nickel nitrate hexahydrate in 40ml of deionized water, stirring and dissolving, transferring into a 50ml reaction kettle, adding a piece of 0.6g of nickel foam cleaned by 3mol of hydrochloric acid, and carrying out hydrothermal reaction in an oven at 120 ℃ for 12 hours. And after the reaction is finished, taking out the foamed nickel, washing to obtain a foamed nickel material with the surface covered with a yellow-green material, putting the foamed nickel material into 40ml of ammonium molybdate aqueous solution with the mass concentration of 40mmol/L, and transferring the foamed nickel material into a 50ml reaction kettle to carry out hydrothermal reaction at 120 ℃ for 10 hours. After the completion of the cleaning, the foamed nickel material with brick red material covered on the surface is obtained, dried and put into a quartz furnace tube of a tube furnace, and the temperature is maintained at 5 percent (5 percent V)_H2/95％V_Ar) And (3) heating to 400 ℃ at the speed of 5 ℃/min in the mixed atmosphere of hydrogen and argon, and keeping for 2 hours, wherein the material is changed from brick red to black, thus obtaining the NiFeMo ternary electrolytic water electrode.

As shown in fig. 4(a) to 4(d), the electron microscopy figure demonstrates that the material exhibits excellent structural stability through retention of the overall morphology structure after prolonged water electrolysis testing.

Claims

1. A NiFeMo ternary electrolytic water electrode is characterized in that: the NiFeMo ternary electrolytic water electrode is NiFe-MoO_xCombining a composite of Ni nano particles and mutually crosslinking the composite to form nano sheets with a hierarchical porous structure and growing the nano sheets on the three-dimensional conductive substrate foamed nickel, wherein the NiFe-MoO_xNiFe-doped non-integral-ratio MoO being amorphous_x；

The preparation method comprises the following specific steps:

(1) mixing iron salt, nickel salt and NH₄Dissolving F and urea in deionized water, adding foamed nickel after complete dissolution, carrying out hydrothermal treatment, cooling and cleaning to obtain a NiFe bimetallic hydroxide loaded with foamed nickel, namely NiFe-LDH/NF, wherein the concentration of ferric salt is 5 mmol/L-20 mmol/L, the concentration ratio of ferric salt to nickel salt is 1: 1-20, the concentration of urea is 100-400 mmol/L, and the concentration of ammonium fluoride is 30-300 mmol/L;

(2) dissolving molybdenum-containing compound in deionized water, adding NiFe-LDH/NF, hydrothermal treating, cooling, and cleaning to obtain Ni-Fe_trace@ NFM/NF, wherein the amount concentration of the molybdenum-containing compound is 5 mmol/L-40 mmol/L, and the molybdenum-containing compound is one of ammonium heptamolybdate, ammonium molybdate or sodium molybdate;

2. The NiFeMo ternary electrolytic water electrode according to claim 1, characterized in that: the ferric salt in the step (1) is one of ferric nitrate, ferric chloride or ferric sulfate, and the nickel salt is one of nickel nitrate, nickel acetate, nickel chloride or nickel sulfate.

3. The NiFeMo ternary electrolytic water electrode according to claim 1, characterized in that: the hydrothermal time in the step (1) is 2-48 h, and the hydrothermal temperature is 100-200 ℃.

4. The NiFeMo ternary electrolytic water electrode according to claim 1, characterized in that: the mass ratio of the foamed nickel to the deionized water in the step (1) is 1: 10-1: 400.

5. The NiFeMo ternary electrolytic water electrode according to claim 1, characterized in that: the hydrothermal time in the step (2) is 2-36 h, and the hydrothermal temperature is 100-200 ℃.

6. The NiFeMo ternary electrolytic water electrode according to claim 1, characterized in that: and (3) the reducing atmosphere is one of hydrogen or carbon monoxide.

7. The NiFeMo ternary electrolytic water electrode according to claim 1, characterized in that: the heat treatment in the step (3) is carried out for 1 to 24 hours at the temperature of between 300 and 800 ℃.