Catalytic electrode and method for preparing the same, and method for electrolyzing water

Abstract

The embodiments of the present disclosure disclose a catalytic electrode, a preparation method thereof, and a water electrolysis method. The catalytic electrode comprises: a metal catalytic electrode body; and a surface active phase on the surface of the metal catalytic electrode body, wherein the surface active phase has a metal atom e g The number of electrons of the orbit is close to 1. The preparation method of the catalytic electrode comprises the following steps: placing a metal catalytic electrode body in an alkaline electrolyte for water electrolysis; applying light irradiation with a specific power to the metal catalytic electrode body; and applying a preset voltage to the metal catalytic electrode body to operate, and in the process of operation, a surface active phase is generated on the surface of the metal catalytic electrode body under the action of light irradiation and the preset voltage. The catalytic electrode can improve the activity of the existing catalytic electrode for water electrolysis.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of catalysis technology, and in particular to a catalytic electrode and a preparation method thereof, and a water electrolysis method. BACKGROUND

[0002] At present, fossil energy hydrogen and industrial by-product hydrogen account for about 99% of the annual hydrogen production in China, while water electrolysis technology for hydrogen production with many advantages such as clean and low carbon accounts for only 1%. The development of water electrolysis technology for hydrogen production is mainly limited by the insufficient activity of the catalytic electrode for water electrolysis, which leads to the problem of high energy consumption of the electrolytic cell.

[0003] At present, the methods for reducing the energy consumption of the electrolytic cell in the prior art mainly focus on the design of the electrode material and the diaphragm, such as developing new high-activity catalytic electrode materials and diaphragms with low interstitial resistance.

[0004] However, the application of these high-performance new materials will cause a series of problems, such as the dissolution of high-activity substances of the electrode under high current density, the collapse of the diaphragm material at high temperature, and the increase of the material cost, which is difficult to support the large-scale application of water electrolysis technology for hydrogen production. SUMMARY

[0005] Therefore, the embodiments of the present disclosure provide a catalytic electrode and a preparation method thereof, and a water electrolysis method, which can improve the activity of the existing catalytic electrode for water electrolysis.

[0006] In a first aspect, the embodiments of the present disclosure provide a catalytic electrode, which adopts the following technical scheme:

[0007] The catalytic electrode comprises:

[0008] a metal catalytic electrode body;

[0009] a surface active phase located on the surface of the metal catalytic electrode body, the number of electrons of the metal atoms in the surface active phase is close to 1. g the e

[0010] Optionally, the metal catalytic electrode body is a nickel foam electrode, a Raney nickel electrode or a foamed iron electrode.

[0011] In a second aspect, the embodiments of the present disclosure provide a preparation method of a catalytic electrode, which is used for preparing the catalytic electrode described in any one of the above, and adopts the following technical scheme:

[0012] The preparation method of the catalytic electrode comprises:

[0013] placing a metal catalytic electrode body in an alkaline electrolyte for water electrolysis;

[0014] applying light with a specific power to the metal catalytic electrode body;

[0015] The metal catalytic electrode body is operated after a preset voltage is applied to the metal catalytic electrode body, and under the action of light and the preset voltage, a surface active phase is generated on the surface of the metal catalytic electrode body during operation.

[0016] Optionally, the specific power ranges from 100 W to 200 W.

[0017] Optionally, the preset voltage ranges from 1.5 V to 2 V.

[0018] Optionally, the operation time ranges from 1.5 h to 3 h.

[0019] Optionally, the alkaline electrolyte is a 1 M to 6 M potassium hydroxide solution or a sodium hydroxide solution.

[0020] In a third aspect, the embodiments of the present disclosure provide an electrolytic water method, which adopts the following technical scheme:

[0021] The electrolytic water method comprises:

[0022] The catalytic electrode described above is placed in an alkaline electrolyte for electrolytic water;

[0023] A working voltage is applied to the catalytic electrode.

[0024] The electrolytic water is performed by taking the surface active phase as a catalyst.

[0025] Optionally, the electrolytic water method further comprises: during the electrolytic water, applying light with specific power to the catalytic electrode.

[0026] In a fourth aspect, the embodiments of the present disclosure provide an electrolytic water method, which adopts the following technical scheme:

[0027] The electrolytic water method comprises:

[0028] A metal catalytic electrode body is placed in an alkaline electrolyte for electrolytic water;

[0029] Light with specific power is applied to the metal catalytic electrode body.

[0030] A working voltage is applied to the metal catalytic electrode body, and under the action of light and the working voltage, a surface active phase is generated on the surface of the catalytic electrode, and the e g The number of electrons of the orbital of the metal atom in the surface active phase is close to 1.

[0031] The electrolytic water is performed by taking the surface active phase as a catalyst.

[0032] The catalytic electrode provided by the embodiments of the present disclosure comprises: a metal catalytic electrode body; and a surface active phase on the surface of the metal catalytic electrode body, wherein the number of electrons of the metal atom in the surface active phase is close to 1. g The number of electrons of the metal atom in the surface active phase is close to 1. The above metal catalytic electrode body is a catalytic electrode for water electrolysis in the prior art. By forming a surface active phase on the surface of the metal catalytic electrode body, and the number of electrons of the metal atom in the surface active phase is close to 1, the electronic structure of the active site of the existing metal catalytic electrode is changed, and the adsorption and desorption behavior of the reaction intermediate is optimized, and the catalytic electrode has higher activity in the process of water electrolysis. g The number of electrons of the metal atom in the surface active phase is close to 1. The number of electrons of the metal atom in the surface active phase is close to 1. The electronic structure of the active site of the existing metal catalytic electrode is changed, and the adsorption and desorption behavior of the reaction intermediate is optimized, and the catalytic electrode has higher activity in the process of water electrolysis.

[0033] The above description is only a summary of the technical solutions of the present disclosure. In order to more clearly understand the technical means of the present disclosure, the contents of the specification can be implemented, and in order to make the above and other purposes, characteristics and advantages of the present disclosure more obvious and easy to understand, the following preferred embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and those skilled in the art can obtain other drawings according to these drawings without creating any creative labor.

[0035] Figure 1 The surface crystal structure diagram of the catalytic electrode provided by the embodiments of the present disclosure is provided.

[0036] Figure 2 The surface crystal structure diagram of the comparative catalytic electrode in the prior art is provided.

[0037] Figure 3 The electronic structure diagram of the Ni atom in the surface active phase provided by the embodiments of the present disclosure is provided.

[0038] Figure 4 The electronic structure diagram of the Ni atom in the active phase in the prior art is provided.

[0039] Figure 5 The x-ray photoelectron spectrum of the surface active phase provided by the embodiments of the present disclosure is provided.

[0040] Figure 6 The x-ray photoelectron spectrum of the active phase in the prior art is provided.

[0041] Figure 7 The flowchart of the preparation method of the catalytic electrode provided by the embodiments of the present disclosure is provided.

[0042] Figure 8A schematic diagram of the change in the electronic structure of a Ni atom in a surfactant phase under illumination is provided for the embodiments of the present disclosure.

[0043] Figure 9 A comparison diagram of Raman spectra of a foam nickel electrode under different illumination intensities is provided for the embodiments of the present disclosure.

[0044] Figure 10 A comparison diagram of the Raman peak area ratio of a foam nickel electrode under different illumination intensities is provided for the embodiments of the present disclosure.

[0045] Figure 11 A comparison diagram of the impedance of a foam nickel electrode under different illumination intensities is provided for the embodiments of the present disclosure.

[0046] Figure 12 A comparison diagram of the water electrolysis performance of a foam nickel electrode under different illumination intensities is provided for the embodiments of the present disclosure.

[0047] Figure 13 A comparison diagram of the water electrolysis performance of a foam iron electrode with and without illumination is provided for the embodiments of the present disclosure.

[0048] Figure 14 A comparison diagram of the water electrolysis performance of a Raney nickel electrode with and without illumination is provided for the embodiments of the present disclosure.

[0049] Figure 15 A change curve of the water electrolysis performance of a foam nickel electrode when the illumination condition changes is provided for the embodiments of the present disclosure. DETAILED DESCRIPTION

[0050] The present disclosure will be described in further detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related content, and not to limit the present disclosure. In addition, it should be noted that only parts related to the present disclosure are shown in the drawings for ease of description.

[0051] It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict. The technical solutions of the present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0052] Unless otherwise specified, the exemplary embodiments / instances shown will be understood to provide exemplary features of various details that can implement the technical concepts of the present disclosure in practice. Therefore, unless otherwise specified, the features of various embodiments / instances can be additionally combined, separated, interchanged and / or rearranged without departing from the technical concepts of the present disclosure.

[0053] Cross-hatching and / or shading in the drawings is generally used to illustrate the boundaries of regions or components of a device, and are thereby not intended to indicate or imply any preference or requirement for particular materials, material properties, dimensions, proportions, commonalities, and / or any other characteristics, attributes, properties, etc. of the components or regions shown. In addition, the dimensions and relative dimensions of the various regions and components shown in the drawings are intended to be exaggerated for the purpose of explanation and are not necessarily drawn to scale. When exemplary embodiments can be implemented differently, a specific process sequence can be performed in a different order than described. For example, two consecutively described processes can be performed substantially simultaneously or in reverse order. In addition, the same reference numerals are used to designate the same components throughout the specification.

[0054] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, to the extent that the terms "including," "includes," "having," "has," "a," "an," "one," and / or "said" are used in the detailed description and / or claims, such terms are intended to be inclusive (i.e., in a manner that says that one or more steps can be performed and / or one or more components can be present) and not exclusive (i.e., in a manner that says that only one step can be performed and / or only one component can be present). Also, as used herein, the terms "substantially," "approximately," and other similar terms are used as terms of approximation and not as terms of degree, unless the context clearly indicates otherwise. That is, they are used to account for inherent variations in measurements, calculations, and / or other sources of variation, which would be understood by those of ordinary skill in the art.

[0055] The embodiments of the present disclosure provide a catalytic electrode, specifically, as shown in Figure 1 The catalytic electrode comprises:

[0056] a metal catalytic electrode body (1) having a surface (2) and a surface (3) opposite to the surface (2); Figure 1 a portion corresponding to a crystal lattice fringe in the lower left corner of the dashed line);

[0057] a surface active phase (4) on the surface (2) of the metal catalytic electrode body (1); Figure 1 a portion corresponding to an amorphous state in the upper right corner of the dashed line), the number of electrons of the e g is close to 1.

[0058] In the process of electrolysis of water, the surface active phase on the surface of the metal catalytic electrode body plays a major catalytic role, in which the electronic structure of the metal atoms has a huge impact on the final activity. The catalytic activity of the conventional metal catalytic electrode is low. In the embodiments of the present disclosure, the number of electrons of the e gThe number of electrons in the orbital of the track is close to 1, which changes the electronic structure of the active site of the traditional metal catalytic electrode, and further optimizes the adsorption and desorption behavior of the reaction intermediate, and exhibits higher activity in the water electrolysis process.

[0059] Optionally, the metal catalytic electrode body in the embodiments of the present disclosure can be a foam nickel electrode, a Raney nickel electrode, or a foam iron electrode, etc.

[0060] Taking the metal catalytic electrode body as a foam nickel electrode as an example, the surface active phase on the surface thereof is NiOOH 1-x Figure 1 (simplified as NiOOH in the art, nickel oxyhydroxide). In addition, in the traditional water electrolysis process, an active phase is also usually formed on the surface of the metal catalytic electrode. Taking the foam nickel electrode as an example, as shown in Figure 1 and Figure 2 , on the one hand, the amount of the active phase on the surface of the existing comparative catalytic electrode is very small, and on the other hand, the amount of the surface active phase of the catalytic electrode in the embodiments of the present disclosure is greatly increased. As shown in Figure 2 , the active phase on the surface of the comparative catalytic electrode can also be represented as NiOOH 1-x (simplified as NiOOH in the art), but as shown in Figure 3 and Figure 4 , the surface active phase NiOOH 1-x in the embodiments of the present disclosure has the number of electrons in the e g orbital of the Ni atom close to 1, while the number of electrons in the e 1-x orbital of the Ni atom in the active phase NiOOH g on the surface of the traditional catalytic electrode is not close to 1.

[0061] The above comparative catalytic electrode can be prepared by placing a 1 cm x 1 cm foam nickel electrode in a beaker containing 1 M potassium hydroxide electrolyte, and placing the beaker in a black box, applying a voltage of 1.6 V vs. RHE by using an electrochemical workstation, and running for 2 h to obtain the comparative catalytic electrode. The catalytic electrode in the embodiments of the present disclosure can be prepared by placing a 1 cm x 1 cm foam nickel electrode in a beaker containing 1 M potassium hydroxide electrolyte, applying a light of 100 W by using a solar simulator, and simultaneously applying a voltage of 1.6 V vs. RHE by using an electrochemical workstation, and running for 2 h to obtain the catalytic electrode in the embodiments of the present disclosure.

[0062] As shown in Figure 5 and Figure 6 , compared with the traditional foam nickel electrode, the surface active phase NiOOH 1-x in the foam nickel electrode in the embodiments of the present disclosure has the number of electrons in the e 3+ / Ni​2+ The peak ratio is increased, which proves that the amount of the active phase generated on the surface of the catalytic electrode in the embodiments of the present disclosure is higher than that of the conventional foam nickel electrode.

[0063] The catalytic electrode in the embodiments of the present disclosure can be prepared in various possible ways. Exemplarily, the embodiments of the present disclosure provide a preparation method of a catalytic electrode for preparing any one of the catalytic electrodes above, such as Figure 7 as shown, the preparation method of the catalytic electrode comprises:

[0064] Step S1, placing the metal catalytic electrode body in an alkaline electrolyte for electrolysis of water.

[0065] Optionally, the alkaline electrolyte is a 1 M-6 M potassium hydroxide solution or a sodium hydroxide solution. The above concentration can be well adapted to the commonly used alkaline electrolyte in industry, and is easier to popularize and apply in industry.

[0066] Step S2, applying light of a specific power to the metal catalytic electrode body.

[0067] Optionally, the power range of the specific power is 100 W-200 W. The light intensity of 100 W-200 W is close to the daily sunlight intensity, which can provide support for subsequent direct use of sunlight, and is conducive to reducing energy consumption.

[0068] Step S3, applying a preset voltage to the metal catalytic electrode body and running. During the running process, under the action of light and the preset voltage, a surface active phase is generated on the surface of the metal catalytic electrode body.

[0069] Optionally, the voltage range of the preset voltage is 1.5 V-2 V. If the preset voltage is too low, it is difficult to drive the surface active phase to be generated, and if the preset voltage is too high, it is not conducive to the stability of the electrode itself.

[0070] Optionally, the time range of the running time is 1.5 h-3 h. If the running time (i.e. the light time) is less than 1.5 h, the surface active phase is not generated completely, and the performance does not reach the optimum. After the light reaches 3 h, the surface active phase and the performance tend to be stable, and there is no need to continue the light.

[0071] Under the light, the surface of the metal catalytic electrode body is more likely to generate a surface active phase, and the number of electrons in the d orbital of the metal atom in the surface active phase is close to 1. g

[0072] Taking the metal catalytic electrode body as a foam nickel electrode, the change process of the electronic structure of the surface active phase generated on the surface of the metal catalytic electrode under the action of light is as shown in Figure 8 After the light is applied, the t 2g ​Electrons in the orbital region are excited and transition to e g track( Figure 8 In the diagram, dashed lines represent electrons that transition after being excited, and arrows represent the transition paths, making e g The number of electrons in the orbital is close to 1, according to e g Electron theory, when e g When the orbital fill is close to 1, the adsorption and desorption steps of the oxygen evolution reaction intermediate become easier, which is more conducive to the occurrence of the oxygen evolution reaction in water electrolysis.

[0073] The following two specific examples illustrate the preparation method of the catalytic electrode. In one example, a 1 cm × 1 cm nickel foam electrode is placed in a beaker containing 1 M potassium hydroxide electrolyte. Irradiation at 100 W is applied using a solar simulator, while simultaneously applying a voltage of 1.6 V vs. RHE using an electrochemical workstation. The process is repeated for 2 hours to obtain a nickel foam electrode with 100 W of light power. In another example, a 1 cm × 1 cm nickel foam electrode is placed in a beaker containing 1 M potassium hydroxide electrolyte. Irradiation at 200 W is applied using a solar simulator, while simultaneously applying a voltage of 1.6 V vs. RHE using an electrochemical workstation. The process is repeated for 2 hours to obtain a nickel foam electrode with 200 W of light power.

[0074] The active phase of three samples—a catalytic electrode (preparation method described previously), a nickel foam electrode at 100 W power, and a nickel foam electrode at 200 W power—was characterized by comparison. Figure 9 and Figure 10 It can be seen that it is located at 475 cm -2 and 554 cm -2 The two nearby peaks correspond to NiOOH 1-x The two characteristic peaks of the substance, A, increase with increasing light intensity. 1g Characteristic peaks and E g The area ratio of the characteristic peaks gradually increased from 1.29 without light to 1.56 at 100 W and 1.61 at 200 W. This indicates that light irradiation induces the formation of more high-valence NiOOH active phases on the surface of the nickel foam electrode, and increasing the light power can enhance this effect to a certain extent.

[0075] Depend on Figure 11 It can be seen that as the light intensity increases, the charge transport impedance of the catalytic electrode gradually decreases, indicating that the charge transport capacity of the catalytic electrode increases after irradiation, and this effect is more pronounced with higher light intensity. Figure 12 It can be seen that during water electrolysis, the current density of the control catalytic electrode without added light is only 10.6 mA cm⁻¹. -2, the current density of the foamed nickel electrode under 100 W power gradually increased to 13.4 mA cm -2 , the current density of the foamed nickel electrode under 200 W power increased to 18.4 mA cm -2 Compared with the comparative catalytic electrode, the current density increased by 73.6%. The above experimental results further confirmed that light can significantly improve the catalytic performance of the catalytic electrode. Further, Figure 12 It can be seen that, on the basis of having applied 100 W of light, after a period of time, the light is strengthened to 200 W, and the continued increase in current density is still observed.

[0076] In addition, it can be seen from Figure 13 and Figure 14 that, for the Raney nickel electrode and the foamed iron electrode, after being prepared by using the preparation method of the catalytic electrode provided in the embodiments of the present disclosure, the light during the preparation process can also improve the activity of the catalytic electrode, thereby improving the current density during the water electrolysis process. The specific results show that, after applying 200 W of light, the catalytic performance of the foamed iron electrode and the Raney nickel electrode is significantly improved, wherein the current density of the Raney nickel electrode increases from 8.4 mA cm -2 to 12.5 mA cm -2 , an increase of about 48.8%; the current density of the foamed iron electrode increases from 10.5 mA cm -2 to 22.6 mA cm -2 , an increase of about 115.2%. The above experimental results can show that the preparation method of the catalytic electrode in the embodiments of the present disclosure has a universal optimization effect on various water electrolysis catalytic electrode materials.

[0077] It can be seen from Figure 15 that, under light, the water electrolysis performance of the foamed nickel electrode gradually improves, and under no light, the performance of the foamed nickel electrode gradually decreases, not only proving that light has a positive effect on the surface active phase performance of the foamed nickel electrode, but also showing that this light-induced performance change is reversible and does not damage the intrinsic structure of the foamed nickel electrode.

[0078] In addition, the embodiments of the present disclosure also provide a water electrolysis method, specifically, the water electrolysis method comprises:

[0079] placing any of the above catalytic electrodes in an alkaline electrolyte for water electrolysis;

[0080] applying a working voltage to the catalytic electrode;

[0081] electrolyzing water by using the surface active phase as a catalyst.

[0082] Optionally, the above water electrolysis method further comprises: applying light of a specific power to the catalytic electrode during the water electrolysis process.

[0083] The above alkaline electrolyte can be a 1 M-6 M potassium hydroxide solution or a sodium hydroxide solution; the above working voltage can be 1.5 V-2 V; and the above specific power can be 100 W-200 W.

[0084] In the above water electrolysis method, the catalytic electrode surface already has a large number of surface active phases, and the number of electrons in the e g The number of electrons in the e

[0085] In addition, the embodiment of the present disclosure further provides a water electrolysis method, specifically, the water electrolysis method comprises:

[0086] placing the metal catalytic electrode body in an alkaline electrolyte for water electrolysis;

[0087] applying light of a specific power to the metal catalytic electrode body;

[0088] applying a working voltage to the metal catalytic electrode body, under the action of the light and the working voltage, a surface active phase is generated on the surface of the catalytic electrode, and the number of electrons in the e g The number of electrons in the e

[0089] electrolyzing water by using the surface active phase as a catalyst.

[0090] The above alkaline electrolyte can be a 1 M-6 M potassium hydroxide solution or a sodium hydroxide solution; the above working voltage can be 1.5 V-2 V; and the above specific power can be 100 W-200 W.

[0091] In the above water electrolysis method, the catalytic electrode surface itself does not have a surface active phase, and in the process of water electrolysis, due to the influence of light, a surface active phase is generated on its surface, and the number of electrons in the e g The number of electrons in the e

[0092] In the description of the specification, the description of the terms "one embodiment / way", "some embodiments / ways", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment / way or example are included in at least one embodiment / way or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment / way or example. Also, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments / ways or examples. In addition, the person skilled in the art can combine and combine the different embodiments / ways or examples described in the specification and the features of the different embodiments / ways or examples, without contradiction.

[0093] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0094] The person skilled in the art should understand that the above-mentioned embodiments are only for the purpose of clearly illustrating the present disclosure, and are not intended to limit the scope of the present disclosure. Based on the above disclosure, other changes or modifications can also be made by those skilled in the art, and these changes or modifications are still within the scope of the present disclosure.

Claims

1. A method for preparing a catalytic electrode, characterized by, The preparation method comprises: placing a metal catalytic electrode body in an alkaline electrolyte for electrolysis of water, wherein the metal catalytic electrode body is a nickel foam electrode or a Raney nickel electrode; applying light with a specific power to the metal catalytic electrode body, wherein the specific power ranges from 100 W to 200 W; The metal catalytic electrode body is operated after a preset voltage is applied to the metal catalytic electrode body, the voltage range of the preset voltage is 1.5V-2V, the time range of the operation time is 1.5h-3h, and under the action of light and the preset voltage, a surface active phase is generated on the surface of the metal catalytic electrode body during the operation, the surface active phase is NiOOH 1-x , and the number of electrons of the e g orbit of the metal atom in the surface active phase is close to 1.

2. The method for preparing a catalytic electrode according to claim 1, characterized in that, the alkaline electrolyte is a 1 M-6 M potassium hydroxide solution or a 1 M-6 M sodium hydroxide solution.

3. A method of electrolyzing water, characterized by, The application further provides a method for electrolysis of water, comprising: placing the catalytic electrode prepared in any one of claims 1-2 in an alkaline electrolyte for electrolysis of water; applying a working voltage to the catalytic electrode, wherein the working voltage ranges from 1.5 V to 2 V; electrolyzing water by using the surface active phase as a catalyst; the method for electrolysis of water further comprises: during the electrolysis of water, applying light with a specific power to the catalytic electrode, wherein the specific power ranges from 100 W to 200 W.

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