阅读说明：本技术 一种氟离子掺杂磷化钴材料及其制备方法及pem电解水制氢应用 (Fluorine ion-doped cobalt phosphide material, preparation method thereof and application of PEM (proton exchange membrane) to water electrolysis hydrogen production ) 是由 俞书宏 吴睿 于 2021-10-20 设计创作，主要内容包括：本发明提供了一种氟离子掺杂磷化钴材料的制备方法。本发明采取了固相反应法制备了生长于CFP上的CoP材料,并通过氟离子掺杂,在保持CoP材料微观结构不变的前提下制备了生长于CFP上的CoP|F材料。该制备方法可以通过仅改变CFP面积实现材料的大规模制备。本发明以制备的CoP|F材料代替商业铂碳作为氢电极材料,用于PEM电解水制氢,其电流密度达到1A m～(-2)所需电压为1.98V,可与商业铂碳组装的PEM器件性能相媲美(1.80V)。(The invention provides a preparation method of a fluorine ion doped cobalt phosphide material. The invention adopts a solid-phase reaction method to prepare the CoP material growing on the CFP, and prepares the CoP | F material growing on the CFP on the premise of keeping the microstructure of the CoP material unchanged by doping fluorine ions. The preparation method can realize large-scale preparation of the material by only changing the CFP area. The prepared CoP | F material is used as a hydrogen electrode material instead of commercial platinum carbon and is used for producing hydrogen by PEM (proton exchange membrane) water electrolysis, and the current density of the material reaches 1A m ‑2 The required voltage is 1.98V, comparable to the performance of a commercial platinum carbon assembled PEM device (1.80V).)

1. A preparation method of a fluorine ion doped cobalt phosphide material is characterized by comprising the following steps:

A) immersing carbon fiber paper serving as a working electrode into a three-electrode electrolytic cell for electrodeposition to obtain cobalt hydroxide Co (OH) growing on the surface of the carbon fiber paper₂The material comprises an electrolyte, a material and a material, wherein the electrolyte is an aqueous solution containing divalent cobalt ions;

B) growing Co (OH) hydroxide on the surface of phosphorus source₂Calcining carbon fiber paper of the material to obtain a cobalt phosphide (CoP) material growing on the surface of the carbon fiber paper;

C) and calcining the carbon fiber paper with the cobalt phosphide CoP material growing on the surface and ammonium fluoride powder to obtain the fluorine ion doped cobalt phosphide CoP | F.

2. The preparation method according to claim 1, wherein the aqueous solution containing divalent cobalt ions is an aqueous solution of one or more of cobalt chloride, cobalt sulfate, and cobalt nitrate;

the concentration of the aqueous solution of divalent cobalt ions was 0.1M.

3. The method according to claim 1, wherein in the step A), the voltage of the electrodeposition is between-0.8V and-1.0V, and the deposition time is 2 to 8 minutes.

4. The method according to claim 1, wherein in step B), the phosphorus source is selected from one or more of sodium hypophosphite powder, elemental phosphorus powder, and phosphine gas;

the molar ratio of the cobalt hydroxide to the phosphorus source is 1: 5-1: 20.

5. the method according to claim 1, wherein in the step B), the calcining temperature is 200 to 400 ℃ and the calcining time is 1 to 3 hours.

6. The method according to claim 1, wherein in step C), the molar ratio of cobalt phosphide to ammonium fluoride is 1: 0.1-1: 1.

7. the method according to claim 1, wherein in step C), the calcination is carried out at a temperature of 300 to 500 ℃ for 1 to 3 hours.

8. The fluorine ion-doped cobalt phosphide material prepared by the preparation method according to any one of claims 1 to 7, wherein the fluorine ion-doped cobalt phosphide material is a nanosheet with a thickness of 100-300 nm.

9. Use of the fluoride ion-doped cobalt phosphide material of claim 8 in the production of hydrogen by electrolysis of water.

10. The application of claim 9, wherein the specific method for producing hydrogen by electrolyzing water is as follows:

the test was carried out using a commercial PEM with a hydrogen electrode of a fluoride ion doped cobalt phosphide material, an oxygen electrode of iridium dioxide coated on carbon paper, a nafion117 membrane between the electrodes as the solid electrolyte and an electrolyte of 80 ℃ in deionized water.

Technical Field

The invention belongs to the technical field of hydrogen production by water electrolysis, and particularly relates to a fluorine ion-doped cobalt phosphide material, a preparation method thereof and application of the cobalt phosphide material in hydrogen production by PEM water electrolysis.

Background

In order to realize the goals of carbon peak reaching and carbon neutralization, the development of a green novel energy source is very important. Hydrogen energy has received much attention in recent years as a clean and sustainable energy source with high efficiency. The existing industrial large-scale hydrogen production method mainly comprises the following steps: the hydrogen production by water gas reforming, the hydrogen production by natural gas reforming, the hydrogen production by alkane cracking and the hydrogen production by chlor-alkali industry still use fossil fuel as main raw materials and are not in line with the targets of 'carbon peak reaching' and 'carbon neutralization'. The current major source of hydrogen is still fossil fuel reforming, not in line with the requirements for green hydrogen. The electrolytic water, especially the PEM electrolytic water, is an effective green hydrogen preparation way; however, only about 2% of hydrogen in China is sourced from this. An important limiting factor is that the electrode material is a noble metal material represented by platinum and iridium, and the large-scale industrial production application is limited by the expensive price and the rare reserves. Therefore, the design of cheap, efficient and stable non-noble metal electrode materials is the key for realizing the large-scale application of PEM water electrolysis hydrogen production.

Because of its abundant reserves, simple synthesis and excellent activity, TMPs are widely used in the field of energy storage and transformation for research, and are a potential substitute for commercial precious metal materials. In order to meet the requirement of hydrogen production by water electrolysis of industrial PEM (proton exchange membrane), the high-current density (A cm) of the high-current density proton exchange membrane is required to be high on the basis of large-scale preparation^-2Order of magnitude) for over 50000 hours. However, the research on TMPs is limited to laboratory level, and the relevant parameters can not meet the requirements of industrial application. Therefore, how to prepare TMPs materials with macroscopic scale and capable of stably running for a long time under high current density is a big problem in the field of hydrogen production by PEM (proton exchange membrane) water electrolysis at present.

Disclosure of Invention

In view of the above, the technical problem to be solved by the present invention is to provide a fluorine ion-doped cobalt phosphide material, a preparation method thereof, and a PEM electrolyzed water hydrogen production application thereof.

The invention provides a preparation method of a fluorine ion doped cobalt phosphide material, which comprises the following steps:

A) immersing carbon fiber paper serving as a working electrode into a three-electrode electrolytic cell for electrodeposition to obtain cobalt hydroxide Co (OH) growing on the surface of the carbon fiber paper₂The material comprises an electrolyte, a material and a material, wherein the electrolyte is an aqueous solution containing divalent cobalt ions;

B) growing Co (OH) hydroxide on the surface of phosphorus source₂Calcining carbon fiber paper of the material to obtain a cobalt phosphide (CoP) material growing on the surface of the carbon fiber paper;

C) and calcining the carbon fiber paper with the cobalt phosphide CoP material growing on the surface and ammonium fluoride powder to obtain the fluorine ion doped cobalt phosphide CoP | F.

Preferably, the aqueous solution containing divalent cobalt ions is one or more of cobalt chloride, cobalt sulfate and cobalt nitrate;

the concentration of the aqueous solution of divalent cobalt ions was 0.1M.

Preferably, in the step A), the voltage of the electrodeposition is-0.8V to-1.0V, and the deposition time is 2-8 minutes.

Preferably, in step B), the phosphorus source is selected from one or more of sodium hypophosphite powder, elemental phosphorus powder and phosphine gas;

the molar ratio of the cobalt hydroxide to the phosphorus source is 1: 5-1: 20.

preferably, in the step B), the calcining temperature is 200-400 ℃ and the calcining time is 1-3 hours.

Preferably, in step C), the molar ratio of cobalt phosphide to ammonium fluoride is 1: 0.1-1: 1.

preferably, in the step C), the calcining temperature is 300-500 ℃ and the calcining time is 1-3 hours.

The invention also provides the fluorine ion-doped cobalt phosphide material prepared by the preparation method, wherein the fluorine ion-doped cobalt phosphide material is a nanosheet with the thickness of 100-300 nm.

The invention also provides application of the fluorine ion doped cobalt phosphide material in hydrogen production by water electrolysis.

Preferably, the specific method for producing hydrogen by electrolyzing water comprises the following steps:

the test was carried out using a commercial PEM with a hydrogen electrode of a fluoride ion doped cobalt phosphide material, an oxygen electrode of iridium dioxide coated on carbon paper, a nafion117 membrane between the electrodes as the solid electrolyte and an electrolyte of 80 ℃ in deionized water.

Compared with the prior art, the invention provides a preparation method of a fluorine ion doped cobalt phosphide material, which comprises the following steps: A) immersing carbon fiber paper serving as a working electrode into a three-electrode electrolytic cell for electrodeposition to obtain oxyhydrogen growing on the surface of the carbon fiber paperCobalt (Co) (OH)₂The material comprises an electrolyte, a material and a material, wherein the electrolyte is an aqueous solution containing divalent cobalt ions; B) growing Co (OH) hydroxide on the surface of phosphorus source₂Calcining carbon fiber paper of the material to obtain a cobalt phosphide (CoP) material growing on the surface of the carbon fiber paper; C) and calcining the carbon fiber paper with the cobalt phosphide CoP material growing on the surface and ammonium fluoride powder to obtain the fluorine ion doped cobalt phosphide CoP | F. The invention adopts a solid-phase reaction method to prepare the CoP material growing on the CFP, and prepares the CoP | F material growing on the CFP on the premise of keeping the microstructure of the CoP material unchanged by doping fluorine ions. The preparation method can realize large-scale preparation of the material by only changing the CFP area. The prepared CoP | F material is used as a hydrogen electrode material instead of commercial platinum carbon and is used for producing hydrogen by PEM (proton exchange membrane) water electrolysis, and the current density of the material reaches 1A m^-2The required voltage is 1.98V, comparable to the performance of a commercial platinum carbon assembled PEM device (1.80V). Through calculation, the energy consumption of the PEM device assembled by CoP | F for electrolyzing water to produce hydrogen is 46.2kWh kg_H2 ^-1The hydrogen production cost is about 2.9 yuan standard formula^-1(0.5 yuan per kilowatt-hour price), substantially in accordance with commercial platinum-carbon assembled PEM devices (49.1 kWh kg of energy and cost, respectively)_H2 ^-1And 3.1 Yuan Standard prescription^-1) Compared with the current industrial electrolyzed water price (about 5 yuan standard prescription)^-1) Has certain advantages. Meanwhile, the cost of the CoP | F material is about 4000 yuan kg^-1The price is greatly lower than that of commercial platinum-carbon material and is 300000 yuan kg^-1。

Drawings

FIG. 1 is a schematic view of a preparation process of the present invention;

FIG. 2 shows the growth of Co (OH) on CFP prepared by the present invention₂A material Scanning Electron Microscope (SEM) image;

FIG. 3 is a Scanning Electron Microscope (SEM) image of a CoP material grown on a CFP prepared by the present invention;

FIG. 4 is a Scanning Electron Microscope (SEM) image of CoP | F material grown on CFP prepared by the present invention;

FIG. 5 is a Transmission Electron Microscope (TEM) image of a partial nanoplate of CoP | F material grown on a CFP prepared by the present invention;

FIG. 6 is a scanning transmission electron microscope element mapping (STEM mapping) of CoP | F material grown on a CFP prepared in accordance with the present invention;

FIG. 7 is an X-ray diffraction (XRD) pattern of CoP material and CoP | F material grown on CFP prepared by the present invention;

FIG. 8 is an X-ray photoelectron spectroscopy (XPS) plot of CoP material and CoP | F material grown on CFP prepared according to the present invention, wherein the left plot is the Co 2P orbital and the right plot is the P2P orbital;

FIG. 9 shows the hydrogen production activity test by water electrolysis of CoP | F materials with different F doping amounts in the invention;

FIG. 10 is a schematic diagram of a PEM electrolyzer device used in the present invention;

FIG. 11 is an activity test of CoP | F material grown on CFP and commercial platinum carbon (Pt/C) material prepared by the present invention for hydrogen production reaction by PEM electrolysis of water;

FIG. 12 is a summary table of the parameters of the CoP | F material grown on CFP and commercial Pt/C material prepared by the present invention for PEM water electrolysis hydrogen production reaction.

Detailed Description

The invention provides a preparation method of a fluorine ion doped cobalt phosphide material, which comprises the following steps:

A) immersing carbon fiber paper serving as a working electrode into a three-electrode electrolytic cell for electrodeposition to obtain cobalt hydroxide Co (OH) growing on the surface of the carbon fiber paper₂The material comprises an electrolyte, a material and a material, wherein the electrolyte is an aqueous solution containing divalent cobalt ions;

B) growing Co (OH) hydroxide on the surface of phosphorus source₂Calcining carbon fiber paper of the material to obtain a cobalt phosphide (CoP) material growing on the surface of the carbon fiber paper;

C) and calcining the carbon fiber paper with the cobalt phosphide CoP material growing on the surface and ammonium fluoride powder to obtain the fluorine ion doped cobalt phosphide CoP | F.

Referring to FIG. 1, FIG. 1 is a schematic view of the preparation process of the present invention.

The invention firstly uses Carbon Fiber Paper (CFP) as a working electrode, wherein the carbon fiber paper is sourced from the general marketAnd (4) selling. Then, the carbon fiber paper is immersed into a three-electrode electrolytic cell for electrodeposition to obtain cobalt hydroxide Co (OH) growing on the surface of the carbon fiber paper₂A material.

Wherein the electrolyte is an aqueous solution containing divalent cobalt ions. The aqueous solution containing divalent cobalt ions is one or more of cobalt chloride, cobalt sulfate and cobalt nitrate;

the concentration of the aqueous solution of divalent cobalt ions was 0.1M.

The voltage of the electrodeposition is-0.8V to-1.0V, preferably any value between-0.8V, -0.9V, -1.0V or-0.8V to-1.0V, and the deposition time is 2 to 8 minutes, preferably any value between 2, 4, 6, 8 or 2 to 8 minutes.

Then, the above-mentioned grown Co (OH)₂The CFP of (1) is placed downstream of the tube furnace and a phosphorus source is placed upstream of the tube furnace and calcined to produce a cobalt phosphide (CoP) material grown on the CFP.

Wherein the phosphorus source is selected from one or more of sodium hypophosphite powder, simple substance phosphorus powder and phosphine gas;

the molar ratio of the cobalt hydroxide to the phosphorus source is 1: 5-1: 20, preferably 1:5, 1:10, 1:15, 1:20, or 1: 5-1: any value between 20.

The calcining temperature is 200-400 ℃, preferably 200, 300, 400, or any value between 200-400 ℃, and the time is 1-3 hours, preferably 1, 1.5, 2, 2.5, 3, or any value between 1-3 hours.

Next, the CFP with the CoP grown thereon was placed downstream of the tube furnace, and ammonium fluoride powder was placed upstream of the tube furnace and calcined to prepare a CoP | F material grown on the CFP.

The molar ratio of the cobalt phosphide to the ammonium fluoride is 1: 0.1-1: 1, preferably 1:0.1, 1:0.3, 1:0.5, 1:0.7, 1:1, or 1: 0.1-1: any value between 1.

The calcining temperature is 300-500 ℃, preferably 300, 400, 500, or any value between 300-500 ℃, and the time is 1-3 hours, preferably 1, 1.5, 2, 2.5, 3, or any value between 1-3 hours.

The invention also provides the fluorine ion-doped cobalt phosphide material prepared by the preparation method, wherein the fluorine ion-doped cobalt phosphide material is a nanosheet with the thickness of 100-300 nm.

The invention also provides application of the fluorine ion doped cobalt phosphide material in hydrogen production by water electrolysis.

The specific method for producing hydrogen by electrolyzing water comprises the following steps:

the test was carried out using a commercial PEM with a hydrogen electrode of a fluoride ion doped cobalt phosphide material, an oxygen electrode of iridium dioxide coated on carbon paper, a nafion117 membrane between the electrodes as the solid electrolyte and an electrolyte of 80 ℃ in deionized water.

Referring to fig. 10, fig. 10 is a schematic diagram of a PEM water electrolyzer device for use in the present invention.

The invention adopts a solid-phase reaction method to prepare the CoP material growing on the CFP, and prepares the CoP | F material growing on the CFP on the premise of keeping the microstructure of the CoP material unchanged by doping fluorine ions. The preparation method can realize large-scale preparation of the material by only changing the CFP area. The prepared CoP | F material is used as a hydrogen electrode material instead of commercial platinum carbon and is used for producing hydrogen by PEM (proton exchange membrane) water electrolysis, and the current density of the material reaches 1A m^-2The required voltage is 1.98V, comparable to the performance of a commercial platinum carbon assembled PEM device (1.80V). Through calculation, the energy consumption of the PEM device assembled by CoP | F for electrolyzing water to produce hydrogen is 46.2kWh kg_H2 ^-1The hydrogen production cost is about 2.9 yuan standard formula^-1(0.5 yuan per kilowatt-hour price), substantially in accordance with commercial platinum-carbon assembled PEM devices (49.1 kWh kg of energy and cost, respectively)_H2 ^-1And 3.1 Yuan Standard prescription^-1) Compared with the current industrial electrolyzed water price (about 5 yuan standard prescription)^-1) Has certain advantages. Meanwhile, the cost of the CoP | F material is about 4000 yuan kg^-1The price is greatly lower than that of commercial platinum-carbon material and is 300000 yuan kg^-1。

The hydrogen electrode material used in the invention is non-noble metal CoP | F, the synthesis method is simple and easy, large-scale preparation is convenient, compared with the current commercial platinum-based noble metal, the price is low, the reserve capacity is rich, and the performance of hydrogen production by PEM (proton exchange membrane) electrolysis can be compared favorably with that of the commercial material.

For further understanding of the present invention, the fluorine ion doped cobalt phosphide material and the preparation method thereof and the PEM electrolytic water hydrogen production application provided by the present invention are described below with reference to the following examples, and the protection scope of the present invention is not limited by the following examples.

Example 1:

commercial Carbon Fiber Paper (CFP) was immersed as a working electrode in a three-electrode electrolytic cell with an electrolyte of 0.1M aqueous cobalt nitrate. Electrodeposition at-1.0V for 6 minutes to prepare cobalt hydroxide (Co (OH) grown on commercial CFP₂) A material.

b. The above-mentioned material is grown with Co (OH)₂The sodium hypophosphite powder was placed upstream of the tube furnace, which was operated at 300 c for 2 hours, to prepare a cobalt phosphide (CoP) material grown on the CFP. The molar ratio of the cobalt hydroxide to the sodium hypophosphite is as follows: 1: 10. the mass of CoP on each CFP was weighed to be about 0.58 mg.

c. A piece of the CFP grown with CoP was placed downstream of the tube furnace and ammonium fluoride powder was placed upstream of the tube furnace, and the tube furnace was operated at 400 ℃ for 1 hour to prepare a CoP if material grown on the CFP. The addition amount of the ammonium fluoride is 0-50 mg, and the corresponding addition amounts are 0mg, 5mg, 10mg, 20mg and 50mg respectively.

FIGS. 4 to 8 are graphs showing the results of the addition of 20mg ammonium fluoride.

The CoP | F material can be used as a Proton Exchange Membrane (PEM) hydrogen electrode for producing hydrogen by electrolyzing water, and comprises the following steps:

a. and (3) testing the performance of CoP | F products with different F doping amounts by adopting laboratory-level water electrolysis hydrogen production (HER), and selecting the product with the optimal performance to perform PEM test.

b. The test was performed using a commercial PEM with a hydrogen electrode of CoP | F material and an oxygen electrode of commercial iridium dioxide (IrO) coated on carbon paper₂) And a nafion117 film is adopted between the two electrodes as a solid electrolyte. The electrolyte is deionized water (DIW) at 80 ℃, and the process is carried out in a fixed voltage rangeThe activity of the strain is tested by cyclic voltammetry, the related energy consumption is calculated by the curve, and the stability of the strain is tested under the condition of constant pressure.

And (4) analyzing the graph result: homogeneous nanoplate (nanoplate size about 200nm) morphology CoP | F-20 products grown on CFP were successfully prepared by SEM, TEM, STEM elemental analysis and XRD testing (fig. 1-7, the numbers behind the products represent the amount of fluorine source added in the precursor), with the doped F atoms evenly distributed on the nanoplate surface (fig. 6). Compared with the XPS results, the Co and P bonds in CoP | F-20 are increased and lose electrons compared with undoped CoP (FIG. 8). This is because F is the most electronegative element and will shift the electrons of Co and P towards it after entering the CoP lattice. Different doping amounts of CoP | F product were used for laboratory-grade HER reactions, and CoP | F-20 was tested for optimal HER activity (fig. 9). Further, CoP | F-20 was used in a commercial PEM electrolyzed water test and showed comparable performance to commercial Pt/C catalysts (see FIGS. 11-12 for detailed data).

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.