Nano needle-shaped three-dimensional porous electrode and its preparation method and application

Abstract

The invention discloses a nano needle-shaped three-dimensional porous electrode and a preparation method and application thereof; ferrous chloride is used as a main solute, metal chloride is used as a secondary solute to prepare a solution, a metal foam net is placed in the solution and stirred, and hierarchical growth of nano hydroxides and metal oxides is achieved through self-regulation of pH, and a FeOOH nano needle-shaped structure grows on the surface of the obtained three-dimensional porous electrode, and metal oxides are modified on the FeOOH nano needle-shaped structure. The preparation method of the invention is simple, easy to operate, and green and environmentally friendly. The prepared nano needle-shaped three-dimensional porous electrode has hydrophilic and gas-repellent properties, good conductivity, good flexibility, and good catalytic activity and stability in catalytic water electrolysis reaction, which is better than most reported water electrolysis catalysts.

Description

Technical Field

[0001] The present invention relates to the technical field of water electrolysis catalytic electrodes, and in particular to a nano needle-shaped three-dimensional porous electrode and a preparation method and application thereof. Background Art

[0002] Hydrogen is an ideal clean fuel with high energy density and high calorific value. Currently, there are many ways to produce hydrogen in the world. Among them, electrolysis of water using renewable energy is a very promising carbon-free hydrogen production method, which has attracted much attention from the academic community. The water electrolysis reaction includes two half reactions, the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), and both are thermodynamically non-spontaneous reactions that require efficient catalysts to drive, so the energy consumption is relatively high. The commercially used HER and OER catalysts are both precious metal powder catalysts (Pt / C or RuO2), which hinders the industrialization of water electrolysis technology. Therefore, the development of cheap and efficient bifunctional electrocatalysts has become a necessary prerequisite for the industrialization of water electrolysis.

[0003] Transition metals are cheap and have easily controllable electronic orbits, so their oxides, sulfides, phosphides, oxyhydroxyls and their complexes show excellent activity in the field of electrocatalytic water splitting. However, even so, they are still significantly inferior to commercial Pt / C and precious metal powder catalysts such as RuO2 in terms of performance and stability. In situ grown three-dimensional porous integrated catalysts have more obvious advantages over powder catalysts in terms of performance and stability, such as greater resistance to bubble impact, high specific surface area exposing more active sites, less prone to agglomeration, and better stability. Therefore, three-dimensional porous electrode materials are increasingly attracting widespread attention from the academic community. However, the factors affecting material growth in an aqueous environment are more complex than those in a non-aqueous environment. How to use green and simple methods to grasp the important parameters in this environment and achieve controllable growth of materials is a key technology for preparing efficient and inexpensive three-dimensional porous electrodes. Summary of the invention

[0004] The purpose of the present invention is to provide a nano-needle-shaped three-dimensional porous electrode and a preparation method and application thereof. The preparation method is simple and the conditions are mild. The prepared nano-needle-shaped three-dimensional porous electrode has hydrophilic and gas-repellent properties and has good catalytic activity for water electrolysis.

[0005] In order to achieve the above objectives, the technical solution adopted by the present invention is:

[0006] The present invention discloses a method for preparing a nano-needle-shaped three-dimensional porous electrode, comprising the following steps:

[0007] (1) adding ferrous chloride to water, stirring and dissolving it completely, then adding metal chloride, stirring continuously at room temperature, the mass ratio of ferrous chloride to metal chloride being 10-20:1, and making the initial pH value of the solution be 0-1;

[0008] (2) immersing the foam metal mesh in the solution obtained in step (1) and continuously stirring, and detecting the pH value of the solution;

[0009] (3) When the pH value of the solution is detected to be 4-5, the reaction is stopped, and the obtained electrode sheet is washed and dried to obtain a nano-needle-shaped three-dimensional porous electrode.

[0010] As a preferred technical solution, the metal chloride is one or more of tungsten chloride, vanadium chloride, molybdenum chloride, cerium chloride, and lanthanum chloride.

[0011] As a preferred technical solution, in step (1), the mass ratio of ferrous chloride to metal chloride is 10:1.

[0012] As a preferred technical solution, the foam metal mesh is a foam nickel mesh, a foam copper mesh, a foam molybdenum mesh, a foam molybdenum-nickel alloy mesh or a foam iron-nickel alloy mesh.

[0013] As a preferred technical solution, in step (2), the foam metal mesh is preliminarily cleaned by ultrasonic cleaning using hydrochloric acid solution, acetone and water at room temperature in sequence.

[0014] The invention also discloses a nano needle-shaped three-dimensional porous electrode prepared by the preparation method.

[0015] The invention also discloses the application of the nano needle-shaped three-dimensional porous electrode in catalytic water electrolysis.

[0016] Beneficial effects of the present invention:

[0017] The invention uses ferrous chloride as the main solute and metal chloride as the secondary solute to prepare a solution, puts a metal foam net into the solution and stirs it, realizes hierarchical growth of nano hydroxide and metal oxide through self-regulation of pH, and grows FeOOH nano needle-like structure on the surface of the obtained three-dimensional porous electrode, and metal oxide is modified on the FeOOH nano needle-like structure. The preparation method of the invention is simple, easy to operate, and green and environmentally friendly. The prepared nano needle-like three-dimensional porous electrode has hydrophilic and gas-repellent properties, good conductivity, good flexibility, good catalytic activity and stability in catalytic water electrolysis reaction, and is superior to most reported water electrolysis catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a low magnification FESEM image of the nano-needle-shaped three-dimensional porous electrode prepared in Example 1;

[0019] Figure 2 This is a high magnification FESEM image of the nano-needle-shaped three-dimensional porous electrode prepared in Example 1;

[0020] Figure 3 This is a low magnification TEM image of the nano-needle-shaped three-dimensional porous electrode prepared in Example 1;

[0021] Figure 4 The nano-needle-shaped three-dimensional porous electrode prepared in Example 1 and Figure 3 HRTEM image of the same position;

[0022] Figure 5 This is a test diagram of the liquid contact angle of the nano-needle-shaped three-dimensional porous electrode prepared in Example 1;

[0023] Figure 6 This is a test diagram of the overall water splitting performance of the nano-needle-shaped three-dimensional porous electrode prepared in Example 1;

[0024] Figure 7 The FESEM low-resolution image and element distribution map of the nano-needle-shaped three-dimensional porous electrode prepared in Example 2;

[0025] Figure 8 The FESEM low-resolution image and element distribution map of the nano-needle-shaped three-dimensional porous electrode prepared in Example 3;

[0026] Fig. 9 The FESEM low-resolution image and element distribution map of the nano-needle-shaped three-dimensional porous electrode prepared in Example 4;

[0027] Fig.10 This is the FESEM low-resolution image and element distribution map of the nanoneedle-shaped three-dimensional porous electrode prepared in Example 5. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described below with reference to the accompanying drawings.

[0029] Example 1

[0030] (1) Add 500 mg of ferrous chloride to 50 ml of water and stir at room temperature to dissolve, then add 50 mg of tungsten chloride and continue stirring at room temperature. At this time, the initial pH value of the solution is 1;

[0031] (2) 2x3 cm 2 The nickel foam meshes of different sizes were cleaned in advance by ultrasonic cleaning with hydrochloric acid solution, acetone and water at room temperature, and then immersed in the solution obtained in step (1) and stirred continuously at 300 revolutions per minute, and the pH value of the solution was tested;

[0032] (3) When the pH value of the solution is detected to be 5, the reaction is stopped, and the obtained electrode sheet is washed and dried to obtain a nano-needle-shaped three-dimensional porous electrode.

[0033] Figure 1This is a low magnification FESEM image of the nano-needle-shaped three-dimensional porous electrode prepared in Example 1. Figure 1 It can be proved that the nanostructure on the surface of the electrode prepared in Example 1 is evenly distributed.

[0034] Figure 2 This is a high magnification FESEM image of the nano-needle-shaped three-dimensional porous electrode prepared in Example 1. Figure 2 It can be proved that the nanostructure on the surface of the electrode prepared in Example 1 is a nano needle structure.

[0035] Figure 3 This is a TEM low magnification image of the nano-needle-shaped three-dimensional porous electrode prepared in Example 1. Figure 3 It can be proved that the electrode prepared in Example 1 has a nano-needle structure and the surface is modified with a composite.

[0036] Figure 4 The nano-needle-shaped three-dimensional porous electrode prepared in Example 1 and Figure 3 HRTEM images of the same position, by Figure 4 It can be proved that the needle-shaped main material of the electrode prepared in Example 1 is FeOOH, and the modifying component is WO3.

[0037] Figure 5 The liquid contact angle test diagram of the nano-needle-shaped three-dimensional porous electrode prepared in Example 1 is shown in FIG. Figure 5 It can be proved that the electrode prepared in Example 1 has super hydrophilicity and possesses a good Wenzel wetting structure.

[0038] Electrode processing and preparation: Cut the dried and ready-to-use electrode sheets into 0.5x1cm 2 Electrode sheets of any size can be used, and the fixture uses a platinum electrode clamp.

[0039] Full water decomposition performance test: Figure 6 This is a graph showing the overall water splitting performance of the nanoneedle-shaped three-dimensional porous electrode prepared in Example 1 in 1M KOH. The overall water splitting voltage is about 1.6V, which is comparable to commercial Pt / C and RuO2 electrodes, indicating that the electrode prepared in Example 1 has excellent overall water splitting activity.

[0040] Example 2

[0041] (1) Add 500 mg of ferrous chloride to 50 ml of water and stir at room temperature to dissolve, then add 50 mg of vanadium chloride and continue stirring at room temperature. At this time, the initial pH value of the solution is 1;

[0042] (2) 2x3 cm 2The nickel foam meshes of different sizes were cleaned in advance by ultrasonic cleaning with hydrochloric acid solution, acetone and water at room temperature, and then immersed in the solution obtained in step (1) and stirred continuously at 300 revolutions per minute, and the pH value of the solution was tested;

[0043] (3) When the pH value of the solution is detected to be 5, the reaction is stopped, and the obtained electrode sheet is washed and dried to obtain a nano-needle-shaped three-dimensional porous electrode.

[0044] Figure 7 The FESEM low-resolution image and element distribution map of the nano-needle-shaped three-dimensional porous electrode prepared in Example 2 are shown in FIG. Figure 7 It can be proved that the electrode prepared in Example 2 was successfully synthesized, and it can be seen from the element distribution diagram that FeOOH was successfully modified by vanadium oxide.

[0045] Example 3

[0046] (1) Add 500 mg of ferrous chloride to 50 ml of water and stir at room temperature to dissolve, then add 50 mg of platinum chloride and continue stirring at room temperature. At this time, the initial pH value of the solution is 1;

[0047] (2) 2x3 cm 2 The nickel foam meshes of different sizes were cleaned in advance by ultrasonic cleaning with hydrochloric acid solution, acetone and water at room temperature, and then immersed in the solution obtained in step (1) and stirred continuously at 300 revolutions per minute, and the pH value of the solution was tested;

[0048] (3) When the pH value of the solution is detected to be 5, the reaction is stopped, and the obtained electrode sheet is washed and dried to obtain a nano-needle-shaped three-dimensional porous electrode.

[0049] Figure 8 The FESEM low-resolution image and element distribution map of the nano-needle-shaped three-dimensional porous electrode prepared in Example 3 are shown in FIG. Figure 8 It can be proved that the electrode prepared in Example 3 was successfully synthesized, and it can be seen from the element distribution diagram that FeOOH was successfully modified by molybdenum oxide.

[0050] Example 4

[0051] (1) Add 500 mg of ferrous chloride to 50 ml of water and stir at room temperature to dissolve, then add 50 mg of cerium chloride and continue stirring at room temperature. At this time, the initial pH value of the solution is 1;

[0052] (2) 2x3 cm 2 The nickel foam meshes of different sizes were cleaned in advance by ultrasonic cleaning with hydrochloric acid solution, acetone and water at room temperature, and then immersed in the solution obtained in step (1) and stirred continuously at 300 revolutions per minute, and the pH value of the solution was tested;

[0053] (3) When the pH value of the solution is detected to be 5, the reaction is stopped, and the obtained electrode sheet is washed and dried to obtain a nano-needle-shaped three-dimensional porous electrode.

[0054] Fig. 9 The FESEM low-resolution image and element distribution map of the nano-needle-shaped three-dimensional porous electrode prepared in Example 4 are shown in FIG. Fig. 9 It can be proved that the electrode prepared in Example 4 was successfully synthesized, and it can be seen from the element distribution diagram that FeOOH was successfully modified by cerium oxide.

[0055] Example 5

[0056] (1) Add 500 mg of ferrous chloride to 50 ml of water and stir at room temperature to dissolve, then add 50 mg of lanthanum chloride and continue stirring at room temperature. At this time, the initial pH value of the solution is 1;

[0057] (2) 2x3 cm 2 The nickel foam meshes of different sizes were cleaned in advance by ultrasonic cleaning with hydrochloric acid solution, acetone and water at room temperature, and then immersed in the solution obtained in step (1) and stirred continuously at 300 revolutions per minute, and the pH value of the solution was tested;

[0058] (3) When the pH value of the solution is detected to be 5, the reaction is stopped, and the obtained electrode sheet is washed and dried to obtain a nano-needle-shaped three-dimensional porous electrode.

[0059] Fig.10 The FESEM low-resolution image and element distribution map of the nano-needle-shaped three-dimensional porous electrode prepared in Example 5 are shown in FIG. Fig.10 It can be proved that the electrode prepared in Example 5 was successfully synthesized, and it can be seen from the element distribution diagram that FeOOH was successfully modified by lanthanum oxide.

[0060] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a nano-needle-shaped three-dimensional porous electrode, characterized in that: The following steps are involved: (1) adding ferrous chloride to water, stirring and dissolving it completely, then adding metal chloride, stirring continuously at room temperature, the mass ratio of ferrous chloride to metal chloride being 10-20:1, and making the initial pH value of the solution be 0-1; (2) immersing the foam metal mesh in the solution obtained in step (1) and continuously stirring, and detecting the pH value of the solution; (3) When the pH value of the solution is detected to be 4-5, the reaction is stopped, and the obtained electrode sheet is washed and dried to obtain a nano-needle-shaped three-dimensional porous electrode.

2. The method for preparing a nano-needle-shaped three-dimensional porous electrode according to claim 1, characterized in that: The metal chloride is one or more of tungsten chloride, vanadium chloride, molybdenum chloride, cerium chloride and lanthanum chloride.

3. The method for preparing a nano-needle-shaped three-dimensional porous electrode according to claim 1, characterized in that: In the step (1), the mass ratio of ferrous chloride to metal chloride is 10:

1.

4. The method for preparing a nano-needle-shaped three-dimensional porous electrode according to claim 1, characterized in that: The foam metal mesh is a foam nickel mesh, a foam copper mesh, a foam molybdenum mesh, a foam molybdenum-nickel alloy mesh or a foam iron-nickel alloy mesh.

5. The method for preparing a nano-needle-shaped three-dimensional porous electrode according to claim 1, characterized in that: In the step (2), the foam metal mesh is preliminarily cleaned by ultrasonic cleaning at room temperature using hydrochloric acid solution, acetone and water in sequence.

6. A nano-needle-shaped three-dimensional porous electrode prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the nano-needle-shaped three-dimensional porous electrode according to claim 6 in catalytic water electrolysis.

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