Metal oxyhydroxide catalyst, metal electrode composite material and preparation method and application of metal oxyhydroxide catalyst and metal electrode composite material

Abstract

The invention discloses a metal oxyhydroxide catalyst, a metal electrode composite material and a preparation method and application of the metal oxyhydroxide catalyst and the metal electrode composite material. The preparation method comprises the following steps: fully contacting a substrate with a metal salt solution, electrifying for first electrochemical treatment, and depositing a catalyst precursor on the surface of the substrate; and fully contacting the substrate deposited with the catalyst precursor with an alkali solution, and electrifying for second electrochemical treatment to prepare the metal oxyhydroxide catalyst. The prepared metal oxyhydroxide catalyst can be stabilized by a self-supporting porous metal electrode, is uniform in distribution, relatively high in loading capacity and firm in combination, and has rich active sites; the material has excellent activity and selectivity when being used in an electro-catalytic methane conversion reaction. Meanwhile, the preparation method disclosed by the invention has the characteristics of being simple and easy to implement, economical, safe, convenient to operate and amplify, high in repeatability and capable of being expanded to various metal oxyhydroxide.

Description

Technical Field

[0001] This invention relates to a catalyst, specifically to a metal hydroxyl oxide catalyst, a porous metal electrode composite material coated with a metal hydroxyl oxide catalyst, and their preparation methods and applications, belonging to the field of catalyst preparation technology. Background Technology

[0002] Compared to the currently widely used thermocatalytic methane conversion technology in industry, electrocatalytic methane conversion technology has the following key advantages: mild conversion conditions, simple reaction equipment, and the ability to be driven by intermittent energy sources. It is a highly promising methane conversion technology for eliminating greenhouse gases at their source. Transition metal-based catalysts have demonstrated excellent methane conversion capabilities in electrocatalytic methane conversion reactions, and these catalysts are inexpensive and abundant, possessing the potential for large-scale development and utilization. Studies have shown that the main active phase of the catalyst is metal hydroxyoxides, but they suffer from stability issues. Furthermore, the preparation of metal hydroxyoxides typically requires a long-term, high-temperature hydrothermal process, resulting in low loading of the obtained metal hydroxyoxides, and the operation is complex and the process is stringent. Therefore, developing new methods for preparing metal hydroxyoxide catalytic materials and realizing their application in electrocatalytic methane conversion technology is of great significance. Summary of the Invention

[0003] The main objective of this invention is to provide a metal hydroxyl oxide catalyst and its preparation method to overcome the shortcomings of the prior art.

[0004] Another objective of this invention is to provide a porous metal electrode composite material coated with a metal hydroxyl oxide catalyst and a method for preparing the same.

[0005] Another object of the present invention is to provide the application of the aforementioned metal hydroxyl oxide catalyst or metal electrode composite material.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: This invention provides a method for preparing a metal hydroxyl oxide catalyst, comprising: A substrate is provided, which is brought into full contact with a metal salt solution. An electrochemical treatment is performed by applying an electric current, and a catalyst precursor is deposited on the substrate surface. The substrate with the catalyst precursor deposited is brought into full contact with an alkaline solution, and a second electrochemical treatment is performed by passing an electric current to obtain a metal hydroxy oxide catalyst.

[0007] In some embodiments, the preparation method includes: placing the substrate in a metal salt solution, performing a first electrochemical treatment using a chronopotential or chronoamperometric method, and depositing a catalyst precursor on the substrate surface.

[0008] In some embodiments, the preparation method includes: placing a substrate with a catalyst precursor deposited thereon in an alkaline solution and performing a second electrochemical treatment using linear voltammetry or cyclic voltammetry to obtain a metal hydroxyl oxide catalyst.

[0009] This invention also provides a metal hydroxyl oxide catalyst prepared by the aforementioned preparation method.

[0010] This invention also provides a method for preparing a metal electrode composite material, comprising: Provide porous metal electrodes; A porous metal electrode is placed in a metal salt solution, and a first electrochemical treatment is performed using a chronopotential method or a chronoamperometry method to deposit a catalyst precursor on the surface of the porous metal electrode. A porous metal electrode with a catalyst precursor deposited on it is placed in an alkaline solution and subjected to a second electrochemical treatment using linear voltammetry or cyclic voltammetry to coat the surface of the porous metal electrode with the prepared metal hydroxyl oxide catalyst, thus obtaining a metal electrode composite material.

[0011] The present invention also provides a metal electrode composite material prepared by the aforementioned preparation method, which includes a porous metal electrode and a metal hydroxyl oxide catalyst coated on the surface of the porous metal electrode.

[0012] This invention also provides the application of the metal hydroxyl oxide catalyst or metal electrode composite material in the electrocatalytic methane conversion reaction.

[0013] Compared with the prior art, the advantages of the present invention are at least as follows: The metal hydroxyl oxide catalyst prepared by this invention can be stabilized by a self-supporting porous metal electrode, exhibiting uniform distribution, high loading, strong bonding, and abundant active sites. This material demonstrates excellent activity and selectivity in the electrocatalytic conversion of methane. Furthermore, the raw material metal salts used in this invention are widely available, inexpensive, and abundant, possessing the potential for large-scale development and utilization. The preparation method is simple, economical, safe, easy to operate and scale up, highly reproducible, and can be extended to various metal hydroxyl oxides. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1This is a scanning electron microscope (SEM) image of the sample obtained in step (5) of Example 2 of the present invention; Figure 2 The image shows the Raman spectrum of the sample obtained in step (5) of Example 2 of this invention. Figure 3 This is a scanning electron microscope (SEM) image of the sample obtained in step (4) of Comparative Example 1 of the present invention; Figure 4 The Raman spectrum of the sample obtained in step (4) of Comparative Example 1 of this invention is shown. Figure 5 For the application of the proton nuclear magnetic resonance spectrum of the electrolyte after the reaction in Example 2 ( 1 (H NMR) image. Detailed Implementation

[0016] In response to the shortcomings of existing technologies, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention, namely, a simple, economical, safe, easy-to-operate, and scale-up method. The main method involves performing two-step electrochemical treatments on a porous metal electrode in a metal salt solution and an alkaline solution, thereby obtaining a porous metal electrode coated with a metal hydroxyl oxide catalyst.

[0017] The following will further explain the technical solution, its implementation process, and its principles. However, it should be understood that within the scope of this invention, the above-mentioned technical features of this invention and the technical features specifically described below (in embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described in detail here.

[0018] As one aspect of the technical solution of this invention, a method for preparing a metal hydroxyl oxide catalyst includes: Provide a base; The substrate is brought into full contact with the metal salt solution, and an electrochemical treatment is performed by applying an electric current to deposit a catalyst precursor on the substrate surface. The substrate with the catalyst precursor deposited is brought into full contact with an alkaline solution, and a second electrochemical treatment is performed by passing an electric current to obtain a metal hydroxy oxide catalyst.

[0019] In some specific embodiments, the metal salt contained in the metal salt solution may include any one or a combination of two or more of nickel nitrate, nickel chloride, cobalt nitrate, cobalt chloride, ferric nitrate, ferric chloride, manganese nitrate, and manganese chloride, but is not limited thereto. The raw material metal salts used in this invention are widely available, inexpensive, and abundant, possessing the potential for large-scale development and utilization.

[0020] Furthermore, the concentration of the metal salt solution is 10~150 mmol / L.

[0021] In some specific embodiments, the preparation method includes: placing the substrate in a metal salt solution, performing a first electrochemical treatment using a chronopotential method or a chronoamperometry method, and depositing a catalyst precursor on the substrate surface.

[0022] Furthermore, the current used in the chronopotential method is set to -10 to -40 mA, and the time is 10 to 60 min.

[0023] Furthermore, the potential used in the chronoamperometry method is set to -1.5 to -0.6 V, and the time is 10 to 60 min.

[0024] In some specific embodiments, the alkaline solution may include any one or a combination of two or more of sodium hydroxide solution, potassium hydroxide solution, ammonia solution, hydrazine hydrate solution, etc., but is not limited to this.

[0025] Furthermore, the concentration of the alkaline solution is 0.1~3 mol / L.

[0026] In some specific embodiments, the preparation method includes: placing a substrate with a catalyst precursor deposited thereon in an alkaline solution and performing a second electrochemical treatment using linear voltammetry or cyclic voltammetry to obtain a metal hydroxyl oxide catalyst.

[0027] Furthermore, the potential of the linear voltammetric scanning method is set to 0.1~1.2 V, the scanning speed is 5~100 mV / s, and the number of cycles is 30~120.

[0028] Furthermore, the potential of the cyclic voltammetric scanning method is set to -0.2~1.2 V, the scanning speed is 5~100 mV / s, and the number of cycles is 10~60.

[0029] In some specific embodiments, the substrate includes a porous metal electrode.

[0030] Furthermore, the porous metal electrode may include any one of the following: nickel foam, nickel felt, nickel mesh, copper foam, titanium felt, stainless steel felt, zinc foam, aluminum foam, and iron-nickel foam, but is not limited to these.

[0031] In some specific embodiments, the preparation method further includes: ultrasonically cleaning the substrate and drying it before bringing the substrate into full contact with the metal salt solution.

[0032] Furthermore, the ultrasonic cleaning time is 15-60 min, the drying temperature is 60-120 ℃, and the drying time is 2-14 h.

[0033] Furthermore, the preparation method further includes: after the second electrochemical treatment is completed, drying the obtained metal hydroxyl oxide catalyst at a temperature of 60~120 °C for a time of 2~14 h.

[0034] In some more specific embodiments, the preparation steps of a metal hydroxyl oxide catalyst of the present invention are as follows: (1) The substrate was ultrasonically cleaned and dried in sequence with acetone, ethanol and deionized water; (2) Prepare a metal salt solution of a certain concentration at room temperature and stir until homogeneous; (3) Place the substrate obtained in step (1) into the solution obtained in step (2) and deposit the catalyst precursor on the substrate surface using chronopotential or chronocurrent methods; (4) Prepare an alkaline solution of a certain concentration at room temperature and stir until homogeneous; (5) Place the substrate obtained in step (3) into the alkaline solution obtained in step (4), perform electrochemical treatment using linear voltammetry or cyclic voltammetry scanning, and then wash and dry with deionized water to obtain the metal hydroxyl oxide catalyst.

[0035] As another aspect of the technical solution of this invention, it also relates to a metal hydroxyl oxide catalyst prepared by the aforementioned method. The obtained catalyst is uniformly coated on the electrode surface in a nanoscale porous network, which can significantly increase the specific surface area of ​​the electrode and expose more active sites on the catalyst. At the same time, the porous structure is also conducive to the mass transfer process of methane reaction molecules and methane conversion product molecules, thereby effectively improving the electrocatalytic performance.

[0036] As another aspect of the technical solution of the present invention, it also relates to a method for preparing a metal electrode composite material, which includes: Provide porous metal electrodes; A porous metal electrode is placed in a metal salt solution, and a first electrochemical treatment is performed using a chronopotential method or a chronoamperometry method to deposit a catalyst precursor on the surface of the porous metal electrode. A porous metal electrode with a catalyst precursor deposited on it is placed in an alkaline solution and subjected to a second electrochemical treatment using linear voltammetry or cyclic voltammetry to coat the surface of the porous metal electrode with the obtained metal hydroxy oxide catalyst, thus obtaining a metal electrode composite material (also known as a "porous metal electrode coated with metal hydroxy oxide catalyst").

[0037] In some specific embodiments, the preparation method includes: subjecting the cleaned and dried porous metal electrode to two-step electrochemical treatment in a metal salt solution and an alkaline solution, and finally cleaning and drying it to obtain a porous metal electrode coated with a metal hydroxyl oxide catalyst.

[0038] Furthermore, in this invention, the metal electrode is first cleaned sequentially with acetone, ethanol and deionized water, then a catalyst precursor is obtained by electrodeposition, and finally the catalyst precursor is electrochemically oxidized, cleaned and dried to obtain a porous metal electrode coated with a metal hydroxyl oxide catalyst.

[0039] In some more specific embodiments, the specific preparation steps of a porous metal electrode coated with a metal hydroxyl oxide catalyst according to the present invention include: (1) The porous metal electrode was ultrasonically cleaned and dried in sequence with acetone, ethanol and deionized water. (2) Prepare a metal salt solution of a certain concentration at room temperature and stir until homogeneous; (3) Place the porous metal electrode obtained in step (1) into the solution obtained in step (2) and deposit the catalyst precursor on the surface of the porous metal electrode using chronopotential or chronocurrent methods; (4) Prepare an alkaline solution of a certain concentration at room temperature and stir until homogeneous; (5) Place the porous metal electrode obtained in step (3) into the alkaline solution obtained in step (4), perform electrochemical treatment using linear voltammetry or cyclic voltammetry scanning, and then wash and dry with deionized water to obtain the porous metal electrode coated with metal hydroxy oxide catalyst.

[0040] Furthermore, the porous metal electrode in step (1) may include, but is not limited to, nickel foam, nickel felt, nickel mesh, copper foam, titanium felt, stainless steel felt, zinc foam, aluminum foam, iron-nickel foam, etc.

[0041] Furthermore, in step (1), the ultrasonic cleaning time is 15~60 minutes, the drying temperature is 60~120 ℃, and the drying time is 2~14 h.

[0042] Furthermore, the limitations of the metal salt solution in step (2) and the chronopotential method or chronocurrent method in step (3) are as described above.

[0043] Furthermore, the limitations of the alkaline solution in step (4) and the linear voltammetry or cyclic voltammetry scanning method in step (5) are as described above.

[0044] Furthermore, in step (5), the drying temperature is 60~120 ℃ and the drying time is 2~14 h.

[0045] In summary, the preparation method of this invention can be extended to various metal hydroxy oxides and is applicable to various metal electrodes. The preparation process is simple, economical, safe, and highly reproducible. Moreover, the entire preparation process does not require replacement of reaction vessels and electrode components, making the preparation process simple, highly consistent, and cost-effective for large-scale application.

[0046] As another aspect of the technical solution of the present invention, it also relates to a metal electrode composite material prepared by the aforementioned preparation method, which includes a porous metal electrode and a metal hydroxyl oxide catalyst coated on the surface of the porous metal electrode.

[0047] Furthermore, the metal hydroxyl oxide catalyst is uniformly distributed on the surface of the porous metal electrode.

[0048] Furthermore, the loading of the metal hydroxyl oxide catalyst in the metal electrode composite material is 1~10 mg / cm³. 2 .

[0049] By means of the above technical solution, the metal hydroxyl oxide catalyst prepared by the present invention can be stabilized by a self-supporting metal electrode, and has a uniform distribution, high loading, strong binding and abundant active sites. This material has excellent activity and selectivity in electrocatalytic methane conversion reaction.

[0050] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. It should be noted that the following embodiments are intended to facilitate understanding of the present invention, and do not constitute any limitation thereof. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the manufacturer.

[0051] Example 1 (1) The nickel felt was ultrasonically cleaned with acetone, ethanol and deionized water for 30 minutes in sequence, and then dried at 75 °C for 10 h. (2) Prepare a 10 mmol / L nickel chloride solution at room temperature and stir until homogeneous; (3) Place the nickel felt obtained in step (1) into the nickel chloride solution obtained in step (2) and treat it at a current of -20 mA for 60 minutes using chronopotential method to deposit a catalyst precursor on the surface of the nickel felt electrode; (4) Prepare a 0.1 mol / L sodium hydroxide solution at room temperature and stir until homogeneous; (5) Place the nickel felt electrode obtained in step (3) into the sodium hydroxide solution obtained in step (4), and use linear voltammetry to scan 30 times at a scanning speed of 5 mV / s in a voltage range of 0.6~1.2 V. Then wash with deionized water and dry at 80 °C for 12 h to obtain the nickel felt electrode coated with nickel hydroxyl oxide catalyst.

[0052] Scanning electron microscopy revealed that the catalyst in the obtained sample was uniformly coated on the surface of the nickel felt electrode, exhibiting a nanoscale porous network structure. Raman spectroscopy indicated that the catalyst in the obtained sample mainly consisted of nickel hydroxyl oxide.

[0053] Example 2 (1) Clean the stainless steel felt with acetone, ethanol and deionized water in sequence for 30 minutes, and dry it at 75 °C for 10 hours. (2) Prepare an 80 mmol / L nickel nitrate solution at room temperature and stir until homogeneous; (3) Place the stainless steel felt obtained in step (1) into the nickel nitrate solution obtained in step (2) and treat it at a current of -20 mA for 45 minutes using chronopotential method to deposit a catalyst precursor on the surface of the stainless steel felt electrode. (4) Prepare a 1 mol / L potassium hydroxide solution at room temperature and stir until homogeneous; (5) Place the sample obtained in step (3) into the potassium hydroxide solution obtained in step (4), and use linear voltammetry to scan 90 times at a scanning speed of 10 mV / s in a voltage range of 0.1~0.6 V. Then wash with deionized water and dry at 80 °C for 12 h to obtain a stainless steel felt electrode coated with nickel hydroxyl oxide catalyst.

[0054] Please see Figure 1 As shown, the scanning electron microscope (SEM) image reveals that the catalyst in the obtained sample is uniformly coated on the surface of the stainless steel felt electrode, exhibiting a nanoscale porous network structure. Please refer to [link / reference]. Figure 2 As shown, the Raman spectrum indicates that the catalyst in the obtained sample is mainly composed of nickel hydroxyl oxide.

[0055] Example 3 (1) The nickel felt was ultrasonically cleaned with acetone, ethanol and deionized water for 30 minutes in sequence, and then dried at 75 °C for 10 h. (2) Prepare a 100 mmol / L nickel nitrate solution at room temperature and stir until homogeneous; (3) Place the nickel felt obtained in step (1) into the nickel nitrate solution obtained in step (2) and treat it at a current of -40 mA for 30 minutes using chronopotential method to deposit a catalyst precursor on the surface of the nickel felt electrode; (4) Prepare a 1 mol / L sodium hydroxide solution at room temperature and stir until homogeneous; (5) Place the nickel felt electrode obtained in step (3) into the sodium hydroxide solution obtained in step (4), and use linear voltammetry to scan 120 times at a scanning speed of 10 mV / s in a voltage range of 0.1~0.6 V. Then wash with deionized water and dry at 80 °C for 12 h to obtain the nickel felt electrode coated with nickel hydroxyl oxide catalyst.

[0056] Scanning electron microscopy revealed that the catalyst in the obtained sample was uniformly coated on the surface of the nickel felt electrode, exhibiting a nanoscale porous network structure. Raman spectroscopy indicated that the catalyst in the obtained sample mainly consisted of nickel hydroxyl oxide.

[0057] Example 4 (1) Clean the stainless steel felt with acetone, ethanol and deionized water in sequence for 30 minutes, and dry it at 75 °C for 10 hours. (2) Prepare a 100 mmol / L cobalt nitrate solution at room temperature and stir until homogeneous; (3) Place the stainless steel felt from step (1) into the cobalt nitrate solution obtained in step (2) and treat it for 30 minutes at a voltage of -1.0 V using the chronoamperometry method to deposit the catalyst precursor on the surface of the stainless steel felt electrode; (4) Prepare a 1 mol / L sodium hydroxide solution at room temperature and stir until homogeneous; (5) Place the stainless steel felt electrode obtained in step (3) into the sodium hydroxide solution obtained in step (4), and use cyclic voltammetry to scan 40 times in a voltage range of -0.1~0.5 V at a scan rate of 5 mV / s. Then wash with deionized water and dry at 80 °C for 12 h to obtain the stainless steel felt electrode coated with cobalt hydroxyl oxide catalyst.

[0058] Scanning electron microscopy revealed that the catalyst in the obtained sample was uniformly coated on the surface of the stainless steel felt electrode, exhibiting a nanoscale porous network structure. Raman spectroscopy indicated that the catalyst in the obtained sample was mainly composed of cobalt hydroxyoxide.

[0059] Example 5 (1) The foamed iron-nickel was ultrasonically cleaned with acetone, ethanol and deionized water for 30 minutes in sequence, and then dried at 75 °C for 10 h. (2) Prepare a 100 mmol / L ferric nitrate solution at room temperature and stir well; (3) Place the foamed iron-nickel obtained in step (1) into the ferric nitrate solution obtained in step (2) and treat it at a voltage of -1.0 V for 60 minutes using the chronoamperometry method to deposit a catalyst precursor on the surface of the foamed iron-nickel electrode; (4) Prepare a 1 mol / L sodium hydroxide solution at room temperature and stir until homogeneous; (5) Place the foamed iron-nickel electrode obtained in step (3) into the sodium hydroxide solution obtained in step (4), and use cyclic voltammetry to scan 60 times in a voltage range of -0.1~0.5 V at a scan rate of 5 mV / s. Then wash with deionized water and dry at 80 °C for 12 h to obtain the foamed iron-nickel electrode coated with iron hydroxyl oxide catalyst.

[0060] Scanning electron microscopy revealed that the catalyst in the obtained sample was uniformly coated on the surface of the foamed iron-nickel electrode, exhibiting a nanoscale porous network structure. Raman spectroscopy indicated that the catalyst in the obtained sample was mainly composed of iron hydroxyl oxide.

[0061] Example 6 (1) The titanium felt was ultrasonically cleaned with acetone, ethanol and deionized water in sequence for 30 minutes and dried at 75 °C for 10 h. (2) Prepare a 100 mmol / L manganese chloride solution at room temperature and stir until homogeneous; (3) Place the titanium felt obtained in step (1) into the manganese chloride solution obtained in step (2) and treat it at a current of -10 mA for 45 minutes using chronopotential method to deposit a catalyst precursor on the surface of the titanium felt electrode. (4) Prepare a 3 mol / L ammonia solution at room temperature and stir until homogeneous; (5) Place the titanium felt electrode obtained in step (3) into the ammonia solution obtained in step (4), and use linear voltammetry to scan 60 times at a scanning speed of 10 mV / s in a voltage range of 0.1~0.6 V. Then rinse with deionized water and dry at 80 °C for 12 h to obtain the titanium felt electrode coated with manganese hydroxyoxide catalyst.

[0062] Scanning electron microscopy revealed that the catalyst in the obtained sample was uniformly coated on the surface of the titanium felt electrode, exhibiting a nanoscale porous network structure. Raman spectroscopy indicated that the catalyst in the obtained sample was mainly composed of manganese hydroxide.

[0063] Example 7 (1) Clean the stainless steel felt with acetone, ethanol and deionized water in sequence for 30 minutes, and dry it at 75 °C for 10 hours. (2) Prepare a 100 mmol / L cobalt nitrate solution at room temperature and stir until homogeneous; (3) Place the stainless steel felt from step (1) into the cobalt nitrate solution obtained in step (2) and treat it for 30 minutes at a voltage of -1.0 V using the chronoamperometry method to deposit the catalyst precursor on the surface of the stainless steel felt electrode; (4) Prepare a 3 mol / L hydrazine hydrate solution at room temperature and stir until homogeneous; (5) Place the stainless steel felt electrode obtained in step (3) into the hydrazine hydrate solution obtained in step (4), and use cyclic voltammetry to scan 40 times in the voltage range of -0.1~0.5 V at a scan rate of 5 mV / s. Then wash with deionized water and dry at 80 °C for 12 h to obtain the stainless steel felt electrode coated with cobalt hydroxyl oxide catalyst.

[0064] Scanning electron microscopy revealed that the catalyst in the obtained sample was uniformly coated on the surface of the stainless steel felt electrode, exhibiting a nanoscale porous network structure. Raman spectroscopy indicated that the catalyst in the obtained sample was mainly composed of cobalt hydroxyoxide.

[0065] Example 8 (1) The foamed nickel was ultrasonically cleaned with acetone, ethanol and deionized water for 30 minutes in sequence, and then dried at 75 °C for 10 h. (2) Prepare a 50 mmol / L nickel nitrate solution at room temperature and stir until homogeneous; (3) Place the nickel foam obtained in step (1) into the nickel nitrate solution obtained in step (2) and treat it at a potential of -0.9 V for 30 minutes using the chronoamperometry method to deposit a catalyst precursor on the surface of the nickel foam electrode; (4) Prepare a 1 mol / L potassium hydroxide solution at room temperature and stir until homogeneous; (5) Place the nickel foam electrode obtained in step (3) into the potassium hydroxide solution obtained in step (4), and use linear voltammetry to scan 60 times at a scanning speed of 10 mV / s in a voltage range of 0.1~0.6 V. Then wash with deionized water and dry at 80 °C for 12 h to obtain the nickel foam electrode coated with nickel hydroxyl oxide catalyst.

[0066] Scanning electron microscopy revealed that the catalyst in the obtained sample was uniformly coated on the surface of the nickel foam electrode, exhibiting a nanoscale porous network structure. Raman spectroscopy indicated that the catalyst in the obtained sample mainly consisted of nickel hydroxyl oxide.

[0067] Example 9 (1) The foamed iron-nickel was ultrasonically cleaned with acetone, ethanol and deionized water for 15 minutes in sequence, and then dried at 60 °C for 14 hours. (2) Prepare a 150 mmol / L ferric nitrate solution at room temperature and stir well; (3) Place the foamed iron-nickel obtained in step (1) into the ferric nitrate solution obtained in step (2) and treat it for 10 minutes at a voltage of -1.5 V using the chronoamperometry method to deposit a catalyst precursor on the surface of the foamed iron-nickel electrode; (4) Prepare a 3 mol / L sodium hydroxide solution at room temperature and stir until homogeneous; (5) Place the foamed iron-nickel electrode obtained in step (3) into the sodium hydroxide solution obtained in step (4), and use cyclic voltammetry to scan 60 times in a voltage range of 0.5~1.2 V at a scanning speed of 100 mV / s. Then wash with deionized water and dry at 60 °C for 14 h to obtain the foamed iron-nickel electrode coated with iron hydroxyl oxide catalyst.

[0068] Scanning electron microscopy revealed that the catalyst in the obtained sample was uniformly coated on the surface of the foamed iron-nickel electrode, exhibiting a nanoscale porous network structure. Raman spectroscopy indicated that the catalyst in the obtained sample was mainly composed of iron hydroxyl oxide.

[0069] Example 10 (1) The stainless steel felt was ultrasonically cleaned with acetone, ethanol and deionized water in sequence for 60 minutes and dried at 120 °C for 2 hours. (2) Prepare a 100 mmol / L cobalt chloride solution at room temperature and stir until homogeneous; (3) Place the stainless steel felt from step (1) into the cobalt chloride solution obtained in step (2) and treat it for 60 minutes at a voltage of -0.6 V using the chronoamperometry method to deposit the catalyst precursor on the surface of the stainless steel felt electrode; (4) Prepare a 3 mol / L hydrazine hydrate solution at room temperature and stir until homogeneous; (5) Place the stainless steel felt electrode obtained in step (3) into the hydrazine hydrate solution obtained in step (4), and use cyclic voltammetry to scan 10 times in a voltage range of -0.2~0.5 V at a scan rate of 5 mV / s. Then wash with deionized water and dry at 120 °C for 2 h to obtain the stainless steel felt electrode coated with cobalt hydroxyl oxide catalyst.

[0070] Scanning electron microscopy revealed that the catalyst in the obtained sample was uniformly coated on the surface of the stainless steel felt electrode, exhibiting a nanoscale porous network structure. Raman spectroscopy indicated that the catalyst in the obtained sample was mainly composed of cobalt hydroxyoxide.

[0071] Comparative Example 1 (1) Clean the stainless steel felt with acetone, ethanol and deionized water in sequence for 30 minutes, and dry it at 75 °C for 10 hours. (2) Prepare an 80 mmol / L nickel nitrate solution at room temperature and stir until homogeneous; (3) Place the stainless steel felt obtained in step (1) into the nickel nitrate solution obtained in step (2) and treat it for 45 minutes at a current of -20 mA using chronopotential method.

[0072] (4) The stainless steel felt electrode coated with nickel hydroxide catalyst is obtained by washing with deionized water and drying at 80 °C for 12 h.

[0073] Please see Figure 3 As shown, the scanning electron microscope (SEM) images reveal that the catalyst in the obtained sample is uniformly coated on the surface of the stainless steel felt electrode, exhibiting a nanoscale porous network structure, but accompanied by densification and pore blockage. Please refer to [link / reference]. Figure 4 As shown, the Raman spectrum indicates that the catalyst in the obtained sample is mainly composed of nickel hydroxide.

[0074] Application Example 1 Electrocatalytic methane conversion reaction experiments were conducted using a nickel felt electrode coated with the nickel hydroxyl oxide catalyst obtained in Example 1.

[0075] 1. Evaluation method for electrocatalytic methane conversion performance: A flow cell was used as the electrolytic cell for testing, a platinum wire was used as the counter electrode, an Hg / HgO electrode was used as the reference electrode, a Nafion membrane was used as the diaphragm, and a 0.1 mol / L potassium carbonate solution was used as the electrolyte. The working electrode was a nickel felt electrode coated with the nickel hydroxyl oxide catalyst prepared in Example 1. Before testing, the electrode was degassed with methane and subsequent tests were conducted under a methane atmosphere.

[0076] 2. Test conditions: Atmosphere: methane; Potential: 0.75 V; Time: 1 h.

[0077] 3. Nickel hydroxyoxide uniformly coated on the surface of a nickel felt electrode was used as an electrocatalyst for methane conversion, successfully converting methane into acetic acid with a product selectivity of 100% and a Faraday efficiency of 64.1%.

[0078] Application Example 2 Electrocatalytic methane conversion reaction experiments were conducted using a stainless steel felt electrode coated with the nickel hydroxyl oxide catalyst obtained in Example 2.

[0079] 1. Evaluation method for electrocatalytic methane conversion performance: A flow cell was used as the electrolytic cell for testing, a platinum wire was used as the counter electrode, an Hg / HgO electrode was used as the reference electrode, a Nafion membrane was used as the diaphragm, and a 0.1 mol / L potassium carbonate solution was used as the electrolyte. The working electrode was a stainless steel felt electrode coated with the nickel hydroxyl oxide catalyst prepared in Example 2. Before testing, the electrode was degassed with methane and subsequent tests were conducted under a methane atmosphere.

[0080] 2. Test conditions: Atmosphere: methane; Potential: 0.75 V; Time: 1 h.

[0081] 3. Nickel hydroxyl oxide catalyst uniformly coated on the surface of a stainless steel felt electrode was used as a methane conversion electrocatalyst, successfully converting methane to acetic acid. The 1H NMR spectrum of the electrolyte after the reaction (…) 1 (H NMR) image see Figure 5 The product selectivity was 100%, and the Faraday efficiency was 70.1%.

[0082] Application Example 3 Electrocatalytic methane conversion experiment was conducted using a stainless steel felt electrode coated with the cobalt hydroxyoxide catalyst obtained in Example 4.

[0083] 1. Evaluation method for electrocatalytic methane conversion performance: A flow cell was used as the electrolytic cell for testing, a platinum wire was used as the counter electrode, an Hg / HgO electrode was used as the reference electrode, a Nafion membrane was used as the diaphragm, and a 0.1 mol / L potassium carbonate solution was used as the electrolyte. The working electrode was a stainless steel felt electrode coated with the cobalt hydroxyl oxide catalyst prepared in Example 4. Before testing, the electrode was degassed with methane and subsequent tests were conducted under a methane atmosphere.

[0084] 2. Test conditions: Atmosphere: methane; Potential: 0.75 V; Time: 1 h.

[0085] 3. Cobalt hydroxyoxide catalyst uniformly coated on the surface of stainless steel felt electrode was used as a methane conversion electrocatalyst to successfully convert methane into acetic acid and ethanol, with product selectivity of 67.4% and 32.6%, respectively, and a total Faraday efficiency of 61.5%.

[0086] Application Example 4 Electrocatalytic methane conversion reaction experiments were conducted using a titanium felt electrode coated with the manganese hydroxyoxide catalyst obtained in Example 6.

[0087] 1. Evaluation method for electrocatalytic methane conversion performance: A flow cell was used as the electrolytic cell for testing, a platinum wire was used as the counter electrode, an Hg / HgO electrode was used as the reference electrode, a Nafion membrane was used as the diaphragm, and a 0.1 mol / L potassium carbonate solution was used as the electrolyte. The working electrode was a titanium felt electrode coated with manganese hydroxyoxide catalyst prepared in Example 6. Before testing, the electrode was degassed with methane and subsequent tests were conducted under a methane atmosphere.

[0088] 2. Test conditions: Atmosphere: methane; Potential: 0.75 V; Time: 1 h.

[0089] 3. The hydroxyl manganese oxide catalyst uniformly coated on the surface of the titanium felt electrode was used as a methane conversion electrocatalyst, successfully converting methane into formic acid and methanol, with product selectivity of 78.5% and 21.5%, respectively, and a total Faraday efficiency of 54.1%.

[0090] Application Example 5 Electrocatalytic methane conversion experiment was conducted using a stainless steel felt electrode coated with the nickel hydroxide catalyst obtained in Comparative Example 1.

[0091] 1. Evaluation method for electrocatalytic methane conversion performance: A flow cell was used as the electrolytic cell for testing, a platinum wire was used as the counter electrode, an Hg / HgO electrode was used as the reference electrode, a Nafion membrane was used as the diaphragm, and a 0.1 mol / L potassium carbonate solution was used as the electrolyte. The working electrode was a stainless steel felt electrode coated with nickel hydroxide catalyst prepared in Example 2. Before testing, the electrode was degassed with methane and subsequent tests were conducted under a methane atmosphere.

[0092] 2. Test conditions: Atmosphere: methane; Potential: 0.75 V; Time: 1 h.

[0093] 3. Nickel hydroxide catalyst uniformly coated on the surface of stainless steel felt electrode was used as a methane conversion electrocatalyst. After the reaction, no products of Application Examples 1-4 or other related products were detected.

[0094] Furthermore, the inventors of this case also conducted experiments with other raw materials, processes, and conditions described in this specification, referring to the foregoing embodiments, and obtained relatively ideal results in all cases. It should be understood that the above descriptions are merely some embodiments of the present invention. It should be noted that those skilled in the art can make other modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A process for the preparation of a metal oxyhydroxide catalyst, characterized in that, include: A substrate is provided, which is brought into full contact with a metal salt solution. An electrochemical treatment is performed by applying an electric current, and a catalyst precursor is deposited on the substrate surface. The substrate with the catalyst precursor deposited is brought into full contact with an alkaline solution, and a second electrochemical treatment is performed by passing an electric current to obtain a metal hydroxy oxide catalyst.

2. The preparation method according to claim 1, characterized in that: The metal salt solution contains any one or more of the following metal salts: nickel nitrate, nickel chloride, cobalt nitrate, cobalt chloride, ferric nitrate, ferric chloride, manganese nitrate, and manganese chloride; and / or the concentration of the metal salt solution is 10~150 mmol / L.

3. The preparation method according to claim 1, characterized in that, include: The substrate is placed in a metal salt solution and subjected to a first electrochemical treatment using a chronopotential or chronoamperotropic method to deposit a catalyst precursor on the substrate surface. Preferably, the current used in the chronopotential method is -10 to -40 mA, and the time is 10 to 60 min; Preferably, the potential used in the timing current method is -1.5 to -0.6 V, and the time is 10 to 60 min.

4. The preparation method according to claim 1, characterized in that: The alkaline solution includes any one or a combination of two or more of sodium hydroxide solution, potassium hydroxide solution, ammonia solution, and hydrazine hydrate solution; and / or, the concentration of the alkaline solution is 0.1~3 mol / L.

5. The preparation method according to claim 1, characterized in that, include: The substrate on which the catalyst precursor is deposited is placed in an alkaline solution, and a second electrochemical treatment is performed using linear voltammetry or cyclic voltammetry to obtain a metal hydroxy oxide catalyst. Preferably, the potential of the linear voltammetric scanning method is 0.1~1.2 V, the scanning speed is 5~100 mV / s, and the number of cycles is 30~120. Preferably, the potential of the cyclic voltammetric scanning method is -0.2~1.2 V, the scanning speed is 5~100 mV / s, and the number of cycles is 10~60.

6. The preparation method according to claim 1, characterized in that: The substrate includes a porous metal electrode; preferably, the porous metal electrode includes any one of nickel foam, nickel felt, nickel mesh, copper foam, titanium felt, stainless steel felt, zinc foam, aluminum foam, and iron-nickel foam. And / or, the preparation method further includes: ultrasonically cleaning the substrate and drying it before fully contacting the substrate with the metal salt solution; preferably, the ultrasonic cleaning time is 15~60 min, the drying temperature is 60~120 ℃, and the drying time is 2~14 h. And / or, the preparation method further includes: after the second electrochemical treatment is completed, drying the obtained metal hydroxyl oxide catalyst at a temperature of 60~120 °C for a time of 2~14 h.

7. A metal hydroxyl oxide catalyst prepared by any one of claims 1-6.

8. A method for preparing a metal electrode composite material, characterized in that, include: Provide porous metal electrodes; A porous metal electrode is placed in a metal salt solution, and a first electrochemical treatment is performed using a chronopotential method or a chronoamperometry method to deposit a catalyst precursor on the surface of the porous metal electrode. A porous metal electrode with a catalyst precursor deposited on it is placed in an alkaline solution and subjected to a second electrochemical treatment using linear voltammetry or cyclic voltammetry to coat the surface of the porous metal electrode with the prepared metal hydroxyl oxide catalyst, thus obtaining a metal electrode composite material.

9. The metal electrode composite material prepared by the preparation method of claim 8, comprising a porous metal electrode and a metal hydroxyl oxide catalyst coated on the surface of the porous metal electrode; Preferably, the metal hydroxyl oxide catalyst is uniformly distributed on the surface of the porous metal electrode; Preferably, the loading of the metal oxyhydroxide catalyst in the metal electrode composite is 1 to 10 mg / cm 2 .

10. The application of the metal hydroxyl oxide catalyst of claim 7 or the metal electrode composite material of claim 9 in the electrocatalytic methane conversion reaction.

Images