WO2022252943A1

WO2022252943A1 - Nano-array material with multi-layer structure, preparation method therefor, and application thereof

Info

Publication number: WO2022252943A1
Application number: PCT/CN2022/092209
Authority: WO
Inventors: 林贻超; 武斌; 陈亮; 张秋菊
Original assignee: 宁波杭州湾新材料研究院; 中国科学院宁波材料技术与工程研究所
Priority date: 2021-06-02
Filing date: 2022-05-11
Publication date: 2022-12-08
Also published as: CN113355686B; CN113355686A

Abstract

Disclosed in the present application are a nano-array material with a multi-layer structure, a preparation method therefor, and an application thereof. The nano-array material with a multi-layer structure comprises: a first structural layer comprising an Ni2P material in a nano-array structure having an electron transport effect; and a second structural layer arranged on the first structural layer, the second structural layer comprising a two-phase structural material formed by NiOOH covering a FeOOH surface. The preparation method comprises: using a hydrothermal method to synthesise NiFe-LDH nano array material and then performing in sequence medium-temperature phosphating and electrochemical activation treatment to obtain a NiOOH@FeOOH@Ni2P nano array material with a multi-layer structure. The NiOOH@FeOOH@Ni2P nano-array material with a multi-layer structure prepared by the present application has excellent electrochemical activity and stability in a seawater electrolysis oxygen evolution reaction, and can be used in an anode catalyst in electrolysed seawater.

Description

A nano-array material with multilayer structure, its preparation method and application

This application is based on and claims the priority of the Chinese patent application with the application number 202110616831.1 and the title of the invention "a nano-array material with multi-layer structure, its preparation method and application" submitted on June 2, 2021.

technical field

This application belongs to the field of nanomaterial preparation and electrochemical catalysis, and relates to a preparation method based on nickel-iron-based materials, in particular to a NiOOH@FeOOH@Ni ₂ P nano-array material with a multilayer structure and its preparation method, and in Application in the field of electrocatalysis for seawater electrolysis oxygen reaction.

Background technique

Hydrogen production by electrolysis of water is currently one of the most effective ways to obtain hydrogen energy with high energy density and zero pollution. There is less than 3.5% fresh water on the earth, and the extremely unbalanced spatial distribution of fresh water resources makes fresh water resources face a serious shortage problem. It is worth noting that seawater, as the most abundant water resource on earth, is more suitable as a hydrogen source for hydrogen production by electrolysis of water. In fact, at this stage, seawater electrolysis still faces various challenges: 1. Oxygen evolution reaction (OER) has a high overpotential. Compared with the hydrogen evolution reaction of two electrons, the OER process of four electrons needs to overcome more Only a high reaction energy barrier can release oxygen, thereby increasing power consumption; 2. OER and chlorine evolution reaction (chlorine evolution reaction, CER) compete at the anode, and reflect a more intense thermodynamic competition reaction in a low pH medium; 3. Chlorine corrosion near the anode, chlorine ions will corrode the catalyst, which will lead to problems such as deactivation of the OER catalyst.

Most of the research in the early years was based on the electrolysis of seawater under acidic conditions for electrochemical performance testing, while electrolytes with lower pH faced problems such as low oxygen evolution reaction efficiency. After decades of research in this field, it has been found that the higher pH of the electrolyte is thermodynamically more conducive to the seawater electrolysis oxygen reaction. Therefore, in order to improve the selectivity of oxygen, most of the current research is on the electrolysis of seawater to produce hydrogen under the electrolysis environment of pH=14. Transition metal (hydr) oxides are a kind of cheap basic oxygen evolution reaction materials under alkaline conditions. However, such catalysts are still limited by the disadvantages of insufficient electrical conductivity in the electrolytic environment. In contrast, transition metal phosphides or nitrides can be used in oxygen evolution reactions in alkaline media due to their fast electron transport. However, the insufficient catalytic activity and poor electrochemical lifetime of transition metal phosphides or nitrides reported in recent years still do not have the value of commercial application.

Based on this, there is an urgent need to develop an inexpensive transition metal catalyst that is suitable for seawater electrolysis with high efficiency and resistance to chloride ion corrosion.

Contents of the invention

In view of the above-mentioned technical status, the main purpose of this application is to provide a NiOOH@FeOOH@Ni ₂ P nano-array material with a multilayer structure and its preparation method, thereby overcoming the deficiencies in the prior art.

Another object of the present application is to provide the application of the NiOOH@FeOOH@Ni ₂ P nano-array material with a multilayer structure as an electrocatalyst in seawater electrolysis of oxygen.

In order to realize the above-mentioned purpose of the invention, the technical scheme adopted in this application includes:

The embodiment of the present application provides a nano-array material with a multilayer structure, which includes:

The first structural layer includes a Ni ₂ P material in a nano-array structure with electron transport function;

A second structural layer disposed on the first structural layer, the second structural layer includes a two-phase structural material formed by covering the surface of FeOOH with NiOOH.

The embodiment of the present application also provides a method for preparing a nano-array material with a multilayer structure, which includes:

NiFe-LDH nano-array materials were synthesized by hydrothermal method;

In a protective atmosphere, in the presence of a phosphorus source, the NiFe-LDH nano-array material is subjected to medium-temperature phosphating by vapor deposition to obtain a phosphating product;

The phosphating product is electrochemically activated to obtain a NiOOH@FeOOH@Ni ₂ P nano-array material, that is, a nano-array material with a multilayer structure.

In some embodiments, the preparation method includes: placing the NiFe-LDH nanoarray material at one end of a reaction chamber of a vapor deposition device, placing a phosphorus source at the other end of the reaction chamber, and placing In the atmosphere, the temperature of the reaction chamber is raised to 300°C-400°C at a selected heating rate, and a medium-temperature phosphating reaction is carried out for 1-4 hours to obtain a phosphating product.

In some embodiments, the preparation method includes: using the phosphating product as a working electrode, performing electrochemical activation treatment by cyclic voltammetry in a selected concentration of electrolyte to obtain NiOOH@FeOOH@Ni ₂ P nano array material.

Further, the number of cycles of the electrochemical activation treatment is 10-100.

The embodiment of the present application also provides a nano-array material with a multi-layer structure prepared by any one of the aforementioned methods.

The embodiment of the present application also provides the application of the nano-array material with a multi-layer structure in the preparation of an electrocatalytic material for electrolysis of oxygen.

The embodiment of the present application also provides an anode catalyst for the electrolytic oxygen decomposition reaction, which includes the nano-array material with a multi-layer structure.

The embodiment of the present application also provides a method for electrolysis of oxygen, which includes:

Using the anode catalyst of the electrolytic oxygen decomposition reaction as a working electrode, and cooperating with a counter electrode, a reference electrode and an electrolyte to form an electrochemical reaction system;

Connect the working electrode, counter electrode, and reference electrode to a power source, so as to generate oxygen by electrolysis.

The embodiment of the present application also provides an oxygen production device, which uses an electrode comprising the anode catalyst for the electrolytic oxygen decomposition reaction.

Compared with the prior art, the present application has at least the following beneficial effects:

1) Compared with commercial IrO ₂ , the NiOOH@FeOOH@Ni ₂ P nanoarray material with multilayer structure provided by this application has lower preparation cost, and has the characteristics of high reactivity and long electrochemical life, which is A promising seawater electrolysis oxygen catalyst;

2) In the simulated seawater electrolyte, the NiOOH@FeOOH@Ni ₂ P nano-array material with multilayer structure provided by this application has high electrochemical activity and excellent electrochemical life in seawater electrolysis oxygen reaction. , can be applied to the anode catalyst in seawater electrolysis. After a series of material characterization analysis, the two-phase structure of the upper layer NiOOH and the lower layer FeOOH produced by the phosphating product on the electrochemically activated surface is more conducive to improving the catalytic performance than the single-phase structure of NiOOH. performance;

3) As a seawater electrolysis catalyst, the NiOOH@FeOOH@Ni ₂ P nano-array material has the lowest overpotential of 259mV at a current density of 100mA cm ^-2 ; the overpotential at a current density of 500mA cm ^-2 It is also only 292mV, and the electrochemical life exceeds 100 hours, and the structure can remain stable.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments described in this application. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic structural view of a NiOOH@FeOOH@Ni ₂ P nano-array material with a multilayer structure in a typical embodiment of the present application;

Fig. 2 is the XRD diagram of the NiOOH@FeOOH@Ni ₂ P nano-array material prepared in Comparative Example 1 and Example 1-2 of the present application;

Figure 3 is a high-resolution TEM image of the NiOOH@FeOOH@Ni ₂ P nanoarray material prepared in Example 1 of the present application;

Fig. 4 is the SEM image of the NiOOH@FeOOH@Ni ₂ P nano-array material prepared in Example 1 of the present application;

Fig. 5 is the in situ Raman diagram of the electrochemical activation of the NiOOH@FeOOH@Ni ₂ P nanoarray material P ₁ prepared in Example 1 of the present application;

Fig. 6 is the electrochemical performance diagram of the NiOOH@FeOOH@Ni ₂ P nano-array material prepared in Comparative Example 1 and Example 1-2 of the present application;

Fig. 7 is the electrochemical lifetime diagram of the NiOOH@FeOOH@Ni ₂ P nano-array material prepared in Example 1 of the present application;

Fig. 8 is a high-resolution TEM image of the NiOOH@FeOOH@Ni ₂ P nano-array material after the reaction of Example 1 of the present application;

Figure 9 is the XRD pattern of the NiOOH@FeOOH@Ni ₂ P nano-array material after the reaction of Example 1 of the present application;

Figure 10 is the SEM image of the NiOOH@FeOOH@Ni ₂ P nano-array material after the reaction of Example 1 of the present application;

Figure 11 is a SEM image of the NiOOH@FeOOH@Ni ₂ P-400 nano-array material prepared in Example 2 of the present application;

Fig. 12 is the XRD figure of the NiFe-LDH that the present application makes;

Fig. 13 is the SEM figure of the material that the comparative example 1 of the present application makes;

Figure 14 is the XRD pattern of the NiOOH@Ni ₃ FeN nano-array material prepared in Comparative Example 2 of the present application;

Figure 15 is the in-situ Raman diagram of the electrochemical activation of material N in Comparative Example 2 of the present application;

Figure 16 shows the NiOOH@FeOOH@Ni ₂ P nanoarray material with a multilayer structure in Example 1 of the present application, the NiOOH@Ni ₃ FeN nanoarray material in Comparative Example 2, and the IrO ₂ material loaded to nickel foam in Comparative Example 3 , comparative example 4 without the NiFe-LDH material of medium temperature phosphating, comparative example 5 without electrochemical activation P ₁ material and comparative example 6 LSV comparison chart of foamed nickel material;

Figure 17a-Figure 17d are the CV curves and electric double layer capacitance performance of the NiOOH@FeOOH@Ni ₂ P nanoarray material with a multilayer structure in Example 1 of the present application and the NiOOH/Ni ₃ FeN nanoarray material in Comparative Example 2 Compare chart.

Detailed ways

As mentioned above, in view of the defects of the prior art, the inventor of this case was able to propose the technical solution of the present application after long-term research and a lot of practice, which is mainly to phosphate the NiFe-LDH nano-array material synthesized by the hydrothermal method at medium temperature, and then The NiOOH@FeOOH@Ni ₂ P nano-array material with multilayer structure was obtained by electrochemical activation. The technical solution, its implementation process and principle will be further explained as follows.

Specifically, please refer to Figure 1, as an aspect of the technical solution of the present application, it involves a nano-array material with a multi-layer structure (that is, NiOOH@FeOOH@Ni ₂ with a multi-layer structure as described above) P nano-array materials), which include:

Further, the second structural layer is in an amorphous state. The Ni ₂ P nanometer array material is covered with NiOOH/FeOOH two-phase material.

Further, from another perspective, the NiOOH@FeOOH@Ni ₂ P nano-array material with a multilayer structure has the following structure: the interior is Ni ₂ P material with electron transport function, the surface layer is NiOOH covered with FeOOH Multiphase species (i.e. two-phase structured materials).

In some embodiments of the present application, the dual-phase structure material forms a dual-phase structure film on the surface of the Ni ₂ P material, and the thinner the better, the thickness of the dual-phase structure film is preferably less than 300 nm, more preferably less than 100 nm.

Compared with commercial IrO ₂ , the NiOOH@FeOOH@Ni ₂ P nanoarray material with multi-layer structure provided by this application has lower cost, and has the characteristics of high reactivity and long electrochemical life. It is a promising seawater electrolysis oxygen catalyst.

As another aspect of the technical solution of the present application, it relates to a method for preparing a NiOOH@FeOOH@Ni ₂ P nano-array material with a multilayer structure, which includes:

NiFe-LDH nano-array materials were synthesized by hydrothermal method;

In some embodiments of the present application, the preparation method comprises:

Put commercial nickel foam into a mixed solution of nickel nitrate and iron nitrate, and grow nickel-iron layered double metal hydroxide (NiFe-LDH nanoarray material) on the nickel foam by hydrothermal method. The NiFe-LDH nano-array material is vapor-phase-deposited by means of medium-temperature phosphating to obtain a phosphating product (hereinafter may be marked as material N);

The vapor-deposited material N is electrochemically activated to obtain the NiOOH@FeOOH@Ni ₂ P nano-array material with a multilayer structure.

Provide a uniform mixed reaction system containing nickel source, iron source, ammonium fluoride, urea and water;

The nickel foam is placed in the homogeneously mixed reaction system, and the nickel foam is grown on the nickel foam at 90° C. to 160° C. for 6 to 24 hours by a hydrothermal method to form the NiFe-LDH nano-array material.

Further, the nickel source includes nickel nitrate, such as nickel nitrate hexahydrate, but not limited thereto.

Further, the iron source includes ferric nitrate, such as ferric nitrate nonahydrate, but not limited thereto.

Place the NiFe-LDH nano-array material at one end of the reaction chamber of the vapor deposition equipment, place the phosphorus source at the other end of the reaction chamber, and make the reaction chamber The temperature of the chamber is raised to 300° C. to 400° C., and a medium-temperature phosphating reaction is carried out for 1 to 4 hours to obtain a phosphating product.

In some embodiments, the phosphorus source includes any one or a combination of two or more of sodium hypophosphite, trioctylphosphine, and triphenylphosphine, but is not limited thereto.

The phosphating product is used as a working electrode, and electrochemical activation treatment is carried out by cyclic voltammetry in an electrolyte solution with a selected concentration to obtain a NiOOH@FeOOH@Ni ₂ P nano-array material.

Further, the electrolyte includes NaOH solution, or a mixed solution of NaOH and NaCl.

Among them, in some more preferred embodiments, the specific process of the preparation method of the NiOOH@FeOOH@Ni ₂ P nano-array material with a multilayer structure of the present application includes the following steps:

(1) nickel nitrate hexahydrate, ferric nitrate nonahydrate, ammonium fluoride and urea are dissolved in water to form clear solution A (i.e. the aforementioned uniformly mixed reaction system); solution A and commercial nickel foam are transferred to a high-pressure reactor, And keep it in an oven at a certain temperature for a period of time, then naturally cool down, wash the excess dark green precipitate growing on the nickel foam, and dry to obtain NiFe-LDH.

(2) The materials or reagents used in step (2) are put into the porcelain boat. Place the NiFe-LDH obtained in step (1) at the end of the quartz tube, weigh a certain mass of phosphorus source (such as sodium hypophosphite) and place it at the front of the quartz tube, heat up to a certain temperature at a certain heating rate under a nitrogen protective atmosphere and retreat Fire for a while to obtain material N.

(3) The material N was used as a working electrode in a certain concentration of NaOH solution (orNaOH+NaCl) to perform electrochemical activation for a certain number of cycles by cyclic voltammetry to obtain a NiOOH@FeOOH@Ni ₂ P nanoarray material with a multilayer structure.

Further, the temperature range of the hydrothermal synthesis in the step (1) is between 90°C and 160°C.

Further, the holding time of the hydrothermal synthesis in the step (1) ranges from 6 to 24 hours.

Further, the concentration range of the nickel source such as nickel nitrate hexahydrate in the homogeneously mixed reaction system in the step (1) is 10-100 mmol L ^-1 .

Further, the concentration range of the iron source such as ferric nitrate nonahydrate in the homogeneously mixed reaction system in the step (1) is 10-100 mmol L ^-1 .

Further, the concentration of ammonium fluoride in the homogeneously mixed reaction system in the step (1) ranges from 0.1 to 0.3 mmol L ^-1 . Among them, ammonium fluoride can play a role in the directional growth of nano-arrays.

Further, the concentration of urea in the homogeneously mixed reaction system in the step (1) ranges from 0.2 to 0.5 mmol L ^-1 . Among them, the role of urea is to hydrolyze to create an alkaline environment, which is conducive to the formation of the precursor NiFe-LDH.

Further, in the step (2), when the size of the nickel foam is 1cm*2.5cm, the amount of the phosphorus source ranges from 0.5g to 1.5g.

Further, the mass range of sodium hypophosphite used in the step (2) is 0.5g-1.5g.

Further, the heating rate of the vapor deposition in the step (2) is between 1-10°C/min, and the vapor deposition time is between 1-4h.

Further, the temperature range in the step (2) is between 300°C and 400°C.

Further, the NaOH concentration in the step (3) ranges from 0.5 to 1.5 mol L ^-1 .

In some embodiments, the electrochemical activation cyclic voltammetry cycle in the step (3) ranges from 10 to 100 cycles.

As another aspect of the technical solution of the present application, it relates to a NiOOH@FeOOH@Ni ₂ P nano-array material with a multi-layer structure prepared by the aforementioned method.

Another aspect of the embodiment of the present application also provides the application of any one of the aforementioned NiOOH@FeOOH@Ni ₂ P nano-array materials with a multilayer structure in the preparation of electrocatalytic materials for electrolysis of oxygen.

Correspondingly, another aspect of the embodiments of the present application also provides an anode catalyst for the electrolysis oxygen decomposition reaction, which includes the NiOOH@FeOOH@Ni ₂ P nano-array material with a multi-layer structure described above.

Further, another aspect of the embodiments of the present application also provides a method for electrolysis of oxygen, which includes:

The anode catalyst for the electrolytic oxygen decomposition reaction is used as a working electrode, and is combined with a counter electrode, a reference electrode (Hg/Hg ₂ Cl ₂ ) and an electrolyte to form an electrochemical reaction system;

Further, the electrolyte includes seawater or simulated seawater (1mol/L NaOH and 0.5mol/L NaCl).

Further, in the electrochemical performance test of the NiOOH@FeOOH@Ni ₂ P nano-array material, the overpotential at 100mA cm ^-2 and 500mA cm ^-2 only needs 259mV and 292mV, and the high current density is 500mA cm ^-2 The stability can be as long as more than 100h.

Correspondingly, another aspect of the embodiments of the present application also provides an oxygen production device, which uses an electrode comprising an anode catalyst for the electrolysis oxygen reaction.

In summary, in the simulated seawater electrolyte, the NiOOH@FeOOH@Ni ₂ P nanoarray material with a multilayer structure provided by this application has high electrochemical activity and excellent electrochemical life, and can be applied to The anode catalyst in seawater electrolysis is obtained through a series of material characterization analysis. The two-phase structure of the upper layer NiOOH and the lower layer FeOOH produced by the material N on the electrochemically activated surface is more conducive to improving the catalytic performance than the single-phase structure of NiOOH.

As a seawater electrolysis catalyst, the NiOOH@FeOOH@Ni ₂ P nano-array material has the lowest overpotential of 259mV at a current density of 100mA cm ^-2 ; the overpotential at a current density of 500mA cm ^-2 is only 292mV, and the electrochemical life is more than 100 hours, and the structure can remain stable.

The technical solutions of the present application will be further described in detail below in conjunction with several preferred embodiments and accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present application, not all of them. It should be pointed out that the following examples are intended to facilitate the understanding of the present application, but do not limit it in any way. Based on the embodiments in the present application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present application. For the experimental methods without specific conditions indicated in the following examples, the conventional conditions or the conditions suggested by the manufacturer are usually followed.

Example 1

1. In this embodiment, in this embodiment, the preparation method of the NiOOH@FeOOH@Ni ₂ P nano-array material with a multilayer structure is as follows:

(1) Preparation of nickel-iron layered double hydroxide (NiFe-LDH) precursor

0.29g nickel nitrate hexahydrate, 0.6g ferric nitrate nonahydrate, 0.24g ammonium fluoride and 0.60g urea were dissolved in 35mL aqueous solution, stirred at room temperature until clarified, then transferred to autoclave and a piece of commercial nickel foam ( 2cm*0.5cm) was placed in the reactor to seal, and heated at 120°C for 8 hours to obtain the NiFe-LDH nanoarray material grown on nickel foam;

(2) Preparation of NiOOH@FeOOH@Ni ₂ P nano-array materials

Place 1 g of sodium hypophosphite at the front end of the quartz tube, place the NiFe-LDH nanoarray material obtained in step (1) at the lower end of the quartz tube, and anneal at a rate of 3 °C/min to 300 °C for 2 Material P ₁ was obtained after natural cooling for 1 hour. Put material _P1 in 1mol L ^-1 NaOH solution, use mercury/mercurous chloride (Hg/Hg ₂ Cl ₂ ) as the reference electrode, and platinum mesh (1cm*1cm) as the counter electrode. Under the voltage range of 1.00-1.45V (vs.RHE), electrochemical activation was performed for 30 cycles by cyclic voltammetry to obtain NiOOH@FeOOH@Ni ₂ P nano-array materials.

The NiOOH@FeOOH@Ni ₂ P nano-array material prepared above was analyzed by X-ray diffraction. Except for the three strong diffraction peaks (located at 44.5°, 51.8° and 76.3°) of the nickel substrate, it can be seen from the figure Seeing the characteristic peak of Ni ₂ P (see Figure 2), the inventors of this case believe that the NiOOH@FeOOH@Ni ₂ P nanoarray material has a Ni ₂ P structure as a whole, and Ni ₂ P with high conductivity can be used for seawater electrolysis Oxygen reacts with electron transport. In the high-resolution TEM image, the interplanar spacings of 0.22nm and 0.19nm correspond to the (111) and (210) planes of Ni ₂ P (see Figure 3). It can be seen from Figure 4 that NiOOH@FeOOH@Ni ₂ P has a nano-array structure, and the thickness of its nanosheets is less than 100nm (see Figure 4). Notably, its staggered nanoarrays also contribute to improved conductivity. In addition, the inventors of this case also analyzed the process of electrochemically activating material P ₁ to produce NiOOH@FeOOH@Ni ₂ P nano-array materials. In addition, the inventors of this case also analyzed the process of electrochemically activating material P ₁ to produce NiOOH@FeOOH@Ni ₂ P nano-array materials. Through in-situ Raman spectroscopy, it was found that in the case of no voltage in 1mol L ^-1 NaOH solution, a very small part of NiOOH appeared (see Figure 5), which may be caused by immersion in alkaline conditions. FeOOH is the dominant part at this time, and as the voltage rises to 1.45V, a large amount of NiOOH is produced on the surface of the catalyst to cover FeOOH. Therefore the FeOOH signal is weakened. In addition, the inventor of this case lowered the potential from 1.50V to 1.25V and found that the Raman signal was basically consistent with that at 1.50V, indicating that the NiOOH-covered FeOOH structure produced was irreversible and had certain stability.

2. The NiOOH@FeOOH@Ni ₂ P nano-array material prepared above was applied to electrocatalytic materials for electrolysis of oxygen in seawater and its electrochemical performance was evaluated:

In the simulated seawater electrolyte (1mol/LNaOH and 0.5mol/LNaCl), mercury/mercurous chloride (Hg/Hg ₂ Cl ₂ ) was used as the reference electrode, platinum mesh (1cm*1cm) was used as the counter electrode, and the prepared The NiOOH@FeOOH@Ni ₂ P nanoarray material was used as the working electrode. Firstly, the AC impedance test is carried out under the condition of 100kHz to 0.1Hz, and the measured solution resistance is about 1.2Ω2. Then, the electrochemical performance of NiOOH@FeOOH@Ni ₂ P nanoarray materials was tested by linear voltammetry (LSV, scan rate: 5mV s ^-1 ). The test results are shown in Figure 6, and the overpotentials at 100mA cm ^-2 and 500mA cm ^-2 are only 259mV and 292mV.

The inventor of this case used a two-electrode system to test the electrochemical life of the NiOOH@FeOOH@Ni ₂ P nano-array material, as follows:

The inventor of this case used 1mol/LNaOH and 0.5mol/LNaCl solution as the electrolyte, platinum mesh (1em*1cm) as the counter electrode, NiOOH@FeOOH@Ni ₂ P prepared as in Example 1 as the working electrode, and The electrochemical lifetime test was carried out at a current density of 500mA em ^-2 , and the electrochemical lifetime was more than 100h (see Figure 7), indicating that the prepared NiOOH@FeOOH@Ni ₂ P nanoarray material has a great potential in seawater electrolysis oxygen reaction. higher activity. The inventors of this case carried out XRD, SEM and TEM characterization analysis of NiOOH@FeOOH@Ni ₂ P after the electrochemical life test was completed. From the XRD characterization in Figure 9, it can be seen that NiOOH@FeOOH@Ni ₂ P still has the structure of Ni ₂ P as a whole. The high-resolution TEM further shows that the interior of NiOOH@FeOOH@Ni ₂ P is Ni ₂ P, and the surface layer may be amorphous NiOOH and FeOOH species (see Figure 8). Not only that, the inventors of this case also observed the microscopic morphology of NiOOH@FeOOH@Ni ₂ P after the reaction. It can be seen from Figure 10 that after the electrochemical lifetime test, NiOOH@FeOOH@Ni ₂ P still has a nano-array structure and has certain electrochemical stability. Based on the above analysis, the inventors of this case believe that the NiOOH on the surface covers the FeOOH two-phase species, which not only provides active sites in the simulated seawater environment, but also protects the internal Ni ₂ P with good conductivity from being corroded, thereby achieving efficient analysis. oxygen reaction.

Example 2

1. In this example, the preparation method of NiOOH@FeOOH@Ni ₂ P-400 nano-array material is as follows:

(1) Preparation of nickel-iron layered double hydroxide (NiFe-LDH) precursor

The preparation conditions are the same as in Example 1.

(2) Preparation of NiOOH@FeOOH@Ni ₂ P nanoarrays

Place 1g of sodium hypophosphite at the front end of the quartz tube, place the NiFe-LDH obtained in step (1) at the lower end of the quartz tube, and in a nitrogen atmosphere, raise the temperature to 400°C at a rate of 3°C/min and anneal for 2 hours and wait for natural Material P ₂ is obtained after cooling down. The electrochemical activation conditions are the same as in Example 1.

The NiOOH@FeOOH@Ni ₂ P-400 nanoarray material prepared above was analyzed by X-ray diffraction. Except for the three strong diffraction peaks (located at 44.5°, 51.8° and 76.3°) of the nickel substrate, the The characteristic peak of Ni ₂ P can be seen in (see Figure 2), so the inventors of this case believe that the NiOOH@FeOOH@Ni ₂ P-400 nanoarray material has a Ni ₂ P structure as a whole, and the highly conductive Ni ₂ P can Used in seawater electrolysis oxygen reaction electron transport. It can be seen from Figure 11 that NiOOH@FeOOH@Ni ₂ P has a nano-array structure, and the thickness of the nano-sheets is less than 100nm. However, the morphology of the nanosheets is wrinkled with the NiOOH@FeOOH@Ni ₂ P in Example 1, which may be caused by the higher phosphating temperature.

The electrochemical test conditions were the same as in Example 1. The test results are shown in Figure 6, the overpotentials are 274mV and 360mV at 100mA cm ^-2 and 500mA cm ^-2 .

Example 3

1. In this example, the preparation method of NiOOH@FeOOH@Ni ₂ P nano-array material is as follows:

(1) Preparation of nickel-iron layered double hydroxide (NiFe-LDH) precursor

Same as Example 1.

(2) Preparation of NiOOH@FeOOH@Ni ₂ P nano-array materials

Place 1g of sodium hypophosphite at the front end of the quartz tube, place the NiFe-LDH obtained in step (1) at the lower end of the quartz tube, and in a nitrogen atmosphere, raise the temperature to 300°C at a rate of 3°C/min and anneal for 2 hours and wait for natural Material P ₄ was obtained after cooling down. The material was electrochemically activated for 10 cycles by cyclic voltammetry in a NaOH solution with a N concentration of 1.5 mol L ^-1 to obtain the NiOOH@FeOOH@Ni ₂ P nanoarray material.

Example 4

(1) Preparation of nickel-iron layered double hydroxide (NiFe-LDH) precursor

Same as Example 1.

(2) Preparation of NiOOH@FeOOH@Ni ₂ P nano-array materials

Place 1g of sodium hypophosphite at the front end of the quartz tube, place the NiFe-LDH obtained in step (1) at the lower end of the quartz tube, and in a nitrogen atmosphere, raise the temperature to 300°C at a rate of 3°C/min and anneal for 2 hours and wait for natural Material P ₅ was obtained after cooling down. The material was electrochemically activated for 60 cycles by cyclic voltammetry in a NaOH solution with a N concentration of 0.5 mol L ^-1 to obtain a NiOOH@FeOOH@Ni ₂ P nanoarray material.

Example 5

In this example, the preparation method of the NiOOH@FeOOH@Ni ₂ P nano-array material with a multilayer structure is as follows:

(1) Preparation of nickel-iron layered double hydroxide (NiFe-LDH) precursor

0.872g nickel nitrate hexahydrate, 0.6g ferric nitrate nonahydrate, 0.24g ammonium fluoride and 0.60g urea were dissolved in 35mL aqueous solution, stirred at room temperature until clarified, then transferred to autoclave and a piece of commercial nickel foam ( 2cm*0.5cm) was placed in the reactor to seal, and heated at 120°C for 8 hours to obtain the NiFe-LDH nanoarray material grown on nickel foam;

(2) Preparation of NiOOH@FeOOH@Ni ₂ P nano-array materials

The preparation conditions are the same as those in Example 1 to obtain the NiOOH@FeOOH@Ni ₂ P nano-array material.

Example 6

(1) Preparation of nickel-iron layered double hydroxide (NiFe-LDH) precursor

0.291g nickel nitrate hexahydrate, 1.01g iron nitrate nonahydrate, 0.24g ammonium fluoride and 0.60g urea were dissolved in 35mL aqueous solution, stirred at room temperature until clarified, then transferred to autoclave and a piece of commercial nickel foam ( 2cm*0.5cm) was placed in the reactor to seal, and heated at 120°C for 8 hours to obtain the NiFe-LDH nanoarray material grown on nickel foam;

(2) Preparation of NiOOH@FeOOH@Ni ₂ P nano-array materials

Example 7

(1) Preparation of nickel-iron layered double hydroxide (NiFe-LDH) precursor

0.291g nickel nitrate hexahydrate, 0.606g ferric nitrate nonahydrate, 0.48g ammonium fluoride and 0.60g urea were dissolved in 35mL aqueous solution, stirred at room temperature until clarified, then transferred to autoclave and a piece of commercial nickel foam ( 2cm*0.5cm) was placed in the reactor to seal, and heated at 160°C for 6 hours to obtain the NiFe-LDH nanoarray material grown on nickel foam;

(2) Preparation of NiOOH@FeOOH@Ni ₂ P nano-array materials

Example 8

(1) Preparation of nickel-iron layered double hydroxide (NiFe-LDH) precursor

0.291g nickel nitrate hexahydrate, 0.606g ferric nitrate nonahydrate, 0.24g ammonium fluoride and 0.30g urea were dissolved in 35mL aqueous solution, stirred at room temperature until clarified, then transferred to autoclave and a piece of commercial nickel foam ( 2cm*0.5cm) was placed in the reactor to seal, and heated at 90°C for 24 hours to obtain NiFe-LDH nanoarray materials grown on nickel foam;

(2) Preparation of NiOOH@FeOOH@Ni ₂ P nano-array materials

Example 9

(1) Preparation of nickel-iron layered double hydroxide (NiFe-LDH) precursor

Preparation condition is identical with embodiment 1;

(2) Preparation of NiOOH@FeOOH@Ni ₂ P nano-array materials

Place 1g of trioctylphosphine at the front end of the quartz tube, place the NiFe-LDH obtained in step (1) at the lower end of the quartz tube, and anneal for 2 hours at a rate of 1°C/min to 300°C under a nitrogen atmosphere. Material P ₆ was obtained after natural cooling. After 100 cycles of electrochemical activation, NiOOH@FeOOH@Ni ₂ P nano-array materials were obtained.

Example 10

(1) Preparation of nickel-iron layered double hydroxide (NiFe-LDH) precursor

Preparation condition is identical with embodiment 1;

(2) Preparation of NiOOH@FeOOH@Ni ₂ P nano-array materials

Place 1g of triphenylphosphine at the front end of the quartz tube, place the NiFe-LDH obtained in step (1) at the lower end of the quartz tube, and anneal at a rate of 10°C/min to 350°C for 1 hour under a nitrogen atmosphere. Material P ₇ was obtained after natural cooling. The electrochemical activation conditions are the same as in Example 1, and NiOOH@FeOOH@Ni ₂ P nano-array materials are obtained.

Example 11

(1) Preparation of nickel-iron layered double hydroxide (NiFe-LDH) precursor

Preparation condition is identical with embodiment 1;

(2) Preparation of NiOOH@FeOOH@Ni ₂ P nano-array materials

Place 1g of sodium hypophosphite at the front end of the quartz tube, place the NiFe-LDH obtained in step (1) at the lower end of the quartz tube, and in a nitrogen atmosphere, raise the temperature to 300°C at a rate of 3°C/min and anneal for 4 hours and wait for natural Material P ₈ was obtained after cooling down. The electrochemical activation conditions are the same as in Example 1, and NiOOH@FeOOH@Ni ₂ P nano-array materials are obtained.

Comparative example 1

1. The difference between this comparative example and Example 1 is that 1g of sodium hypophosphite is placed at the front end of the quartz tube, and the NiFe-LDH obtained in step (1) is placed at the lower end of the quartz tube. /min The heating rate was increased to 200°C for 2 hours and annealed for 2 hours to obtain material P ₃ after natural cooling. The electrochemical activation conditions are the same as in Example 1.

The material _P3 prepared above was analyzed by X-ray diffraction, and the material only contained three strong diffraction peaks (located at 44.5°, 51.8° and 76.3°) of the nickel substrate. Therefore, the inventors of this case believe that NiFe-LDH cannot achieve phosphating under the above annealing conditions ( FIG. 2 ).

2. The material _P3 prepared above is applied to the electrocatalytic material for electrolysis of oxygen in seawater and its electrochemical performance is evaluated

The electrochemical test conditions were the same as in Example 1. The test results are shown in Figure 6, and there is basically no performance when the voltage is less than 1.6V.

Comparative example 2

1. In this comparative example, the preparation method of NiOOH@Ni ₃ FeN nano-array material is as follows:

(1) Preparation of nickel-iron layered double hydroxide (NiFe-LDH) precursor

Same as Example 1.

(2) Preparation of NiOOH@Ni ₃ FeN nano-array materials

Put the NiFe-LDH obtained in step (1) into a quartz tube, pass through high-purity ammonia, increase the temperature at a rate of 10 °C/min to 500 °C and anneal for 2 hours, and then cool down naturally to obtain material N. The material N was electrochemically activated for 30 cycles by cyclic voltammetry in a certain concentration of NaOH solution to obtain the NiOOH@Ni ₃ FeN nanoarray material.

The NiOOH@Ni ₃ FeN nanoarray material prepared above was analyzed by X-ray diffraction, except that the material contained three strong diffraction peaks (located at 44.5°, 51.8° and 76.3°) of the nickel substrate, as can be seen from Figure 14 According to the characteristic peak of Ni ₃ FeN, the NiOOH@Ni ₃ FeN nanoarray material has a Ni ₃ FeN structure as a whole, and the highly conductive Ni ₃ FeN can be used for electron transport in seawater electrolysis oxygen reaction. In addition, we also analyzed the process of the electrochemical activation of material N to produce NiOOH@Ni ₃ FeN nanoarray materials. It was found by in situ Raman spectroscopy that no NiOOH or FeOOH signal was generated in 1 mol L ^-1 NaOH solution without voltage application (see Figure 15). As the voltage increased to 1.45V, there were weak peaks at 471cm ^-1 and 547cm ^-1 in the Raman shift, which indicated that NiOOH species were generated on the surface of Ni ₃ FeN.

2. The NiOOH@Ni ₃ FeN nano-array material prepared above was applied to electrocatalytic materials for electrolysis of oxygen in seawater and its electrochemical performance was evaluated

The electrochemical test conditions were the same as in Example 1. The test results are shown in Figure 16. Compared with the NiOOH@FeOOH@Ni ₂ P nano-array material with a multilayer structure in Example 1, the NiOOH@Ni ₃ FeN nano-array material needs to output a current density of 100mA cm ^-2 The overpotential is 293mV, while the overpotential at the industrial grade current density of 500mA cm ^-2 reaches 330mV. Because the electrochemically active area (ECSA) is proportional to the electric double layer capacitance. The inventors of this case used electric double layer capacitance to qualitatively compare the electrochemically active areas of different materials. It can be seen from Fig. 17a-Fig. 17d that the electric double layer capacitance (103.3mF cm ^-2 ) of NiOOH@Ni ₃ FeN is close to that of NiOOH@FeOOH@Ni ₂ P. In the case of close electrochemical active area, the performance of NiOOH@FeOOH@Ni ₂ P is significantly better than that of NiOOH@Ni3FeN. It shows that the two-phase structure of NiOOH covering FeOOH on the surface is more conducive to the occurrence of seawater electrolysis oxygen reaction than the single-layer structure of NiOOH.

Comparative example 3

1, in this comparative example, load to the _IrO of nickel foam The preparation method of the material is as follows:

Disperse 50 mg of commercial _IrO2 and 60 μL of 5w% Nafion solution in 540 μL of ethanol and 400 μL of deionized water. The above mixture was sonicated for 30 minutes. The obtained dispersion was coated on a piece of cleaned (0.5cm*2cm) nickel foam, and dried overnight for later use.

2. The above prepared _IrO2 material loaded onto nickel foam is applied to the electrocatalytic material for electrolysis of oxygen in seawater and the electrochemical performance evaluation is carried out:

The electrochemical test conditions were the same as in Example 1. It can be seen from Fig. 16 that the performance of commercial _IrO2 is far inferior to the electrochemical performance of NiOOH@FeOOH@ _Ni2P with multilayer structure in Example 1.

Comparative example 4

Compared with Example 1, this comparative example differs in that: the intermediate temperature phosphating step is missing, and the obtained material is NiFe-LDH, and its overpotential needs 304mV and 373mV at 100mA cm ^-2 and 500mA cm ^-2 (as shown in Figure 16 shown). The electrochemical performance is worse than the material performance of Example 1.

Comparative example 5

Compared with Example 1, the difference between this comparative example is that the electrochemical activation step is missing, and the overpotential of the obtained material at 100mA cm ^-2 and 500mA cm ^-2 needs to be 261mV and 302mV (as shown in Figure 16). The electrochemical performance is worse than the material performance of Example 1.

Comparative example 6

Compared with Example 1, this comparative example differs in that: only nickel foam as the base is used for the electrochemical performance test. The electrochemical performance is far inferior to the material performance of Example 1 (as shown in FIG. 16 ).

In addition, the inventor of the present case also conducted tests with reference to the foregoing examples, using other raw materials, process operations, and process conditions mentioned in this specification, and all obtained satisfactory results.

Although the present application has been described with reference to illustrative embodiments, it will be understood by those skilled in the art that various other changes, omissions and/or additions may be made without departing from the spirit and scope of the present application and that substantial, etc. Effects replace elements of the described embodiments. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the application without departing from its scope. Therefore, it is not intended that the application be limited to the particular embodiments disclosed for carrying out this application, but that the application will cover all embodiments falling within the scope of the appended claims.

Claims

A nano-array material with a multilayer structure, characterized in that it comprises:

The first structural layer includes a Ni 2 P material in a nano-array structure with electron transport function;

A second structural layer disposed on the first structural layer, the second structural layer includes a two-phase structural material formed by covering the surface of FeOOH with NiOOH.
The nano-array material with multi-layer structure according to claim 1, characterized in that: the two-phase structure material forms a two-phase structure film on the surface of the Ni 2 P material, and the thickness of the two-phase structure film is less than 300 nm.
The nano-array material with multi-layer structure according to claim 2, characterized in that: the thickness of the dual-phase structure thin film is less than 100 nm.
A method for preparing a nano-array material with a multilayer structure, characterized in that it comprises:

NiFe-LDH nano-array materials were synthesized by hydrothermal method;

In a protective atmosphere, in the presence of a phosphorus source, the NiFe-LDH nano-array material is subjected to medium-temperature phosphating by vapor deposition to obtain a phosphating product;

The phosphating product is electrochemically activated to obtain a NiOOH@FeOOH@Ni 2 P nano-array material, that is, a nano-array material with a multilayer structure.
The preparation method according to claim 4, characterized in that it comprises:

Provide a uniform mixed reaction system containing nickel source, iron source, ammonium fluoride, urea and water;

The foamed nickel is placed in the homogeneously mixed reaction system, and the nickel foam is grown on the foamed nickel at 90° C. to 160° C. for 6 to 24 hours by a hydrothermal method to form a NiFe-LDH nanometer array material.
The preparation method according to claim 5, characterized in that: the nickel source includes nickel nitrate; the iron source includes iron nitrate;

And/or, the concentration of the nickel source in the uniformly mixed reaction system is 10-100 mmol L -1 ;

The concentration of the iron source in the uniformly mixed reaction system is 10-100 mmol L -1 ;

The concentration of ammonium fluoride in the uniformly mixed reaction system is 0.1-0.3 mmol L -1 ;

The concentration of urea in the uniformly mixed reaction system is 0.2-0.5 mmol L -1 .
The preparation method according to claim 4, characterized in that it comprises: placing the NiFe-LDH nano-array material at one end of a reaction chamber of a vapor deposition device, placing a phosphorus source at the other end of the reaction chamber, In a protective atmosphere, the temperature of the reaction chamber is raised to 300° C.-400° C. at a selected heating rate, and a medium-temperature phosphating reaction is carried out for 1-4 hours to obtain a phosphating product.
The preparation method according to claim 7, characterized in that: the phosphorus source comprises any one or a combination of two or more of sodium hypophosphite, trioctylphosphine and triphenylphosphine.
The preparation method according to claim 7, characterized in that: the heating rate is 1-10° C./min.
The preparation method according to claim 4, characterized in that it comprises: using the phosphating product as a working electrode, performing electrochemical activation treatment by cyclic voltammetry in an electrolyte with a selected concentration to obtain NiOOH@FeOOH@Ni 2 P nano-array material; the electrolyte includes NaOH solution, or a mixed solution of NaOH and NaCl; the selected concentration is 0.5-1.5mol L -1 ; the number of cycles of the electrochemical activation treatment is 10-100 .
A nano-array material with a multilayer structure prepared by the method according to any one of claims 4-10.
Application of the nano-array material with a multilayer structure described in any one of claims 1-3, 11 in the preparation of electrocatalytic materials for electrolysis of oxygen.
An anode catalyst for the electrolytic oxygen decomposition reaction, characterized in that it comprises the nano-array material with a multi-layer structure according to any one of claims 1-3, 11.
A method for electrolysis of oxygen, characterized in that it comprises:

Adopting the anode catalyst of the electrolysis oxygen reaction described in claim 13 as the working electrode, and cooperating with the counter electrode, the reference electrode and the electrolyte to form an electrochemical reaction system;

Connect the working electrode, counter electrode, and reference electrode to a power source, so as to generate oxygen by electrolysis.
The electrolytic oxygen analysis method according to claim 14, characterized in that: the electrolyte includes seawater or simulated seawater.