An ultra-low-ruthenium-loading porous cathode material, a preparation method and application thereof

Abstract

The present application relates to the technical field of ruthenium-based catalyst, in particular to a kind of super-low ruthenium load porous cathode material and its preparation method and application, method includes the following steps: dissolving cobalt salt and organic ligand in mixed solvent, prepare mixed solution, the organic ligand is terephthalic acid or 2,6-naphthalene dicarboxylic acid, the mixed solvent is composed of N,N-dimethylformamide, water and ethanol mixture;The electrode matrix after pretreatment is placed in the mixed solution, and the porous cathode material is prepared after reaction;The porous cathode material is placed in ruthenium salt solution, and the super-low ruthenium load porous cathode material is prepared after reaction.The present application realizes the high reduction activity of chlorinated organic matter under the condition of super-low ruthenium load by coupling porous nanostructure and atomic dispersion ruthenium active site, and greatly improves the atomic utilization rate of ruthenium.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ruthenium-based catalysts, in particular to a porous cathode material with ultra-low ruthenium loading and a preparation method and application thereof. BACKGROUND

[0002] Chlorinated organic compounds are important chemical production raw materials and organic synthesis intermediates, widely used in electronic, leather-making, pharmaceutical and other industries. However, most of the chlorinated organic compounds have the effects of "carcinogenic, teratogenic and mutagenic" and are difficult to biodegrade, causing great threat to the ecological environment and human health.

[0003] At present, the technologies for removing chlorinated organic compounds in wastewater mainly include physical adsorption, biodegradation, advanced oxidation, chemical reduction and electrocatalytic reduction, among which the electrocatalytic reduction technology is considered as an "environmentally friendly" treatment technology because it does not need to add chemical reagents, has mild reaction conditions and no secondary pollution. The core basis of the electrocatalytic reduction technology is the cathode material. Although many studies use palladium-based cathodes for electrocatalytic reduction of chlorinated organic compounds and have achieved good treatment effects, however, the palladium reserves are small and the price is expensive, which significantly increases the cost of pollutant treatment.

[0004] Ruthenium-based catalysts have similar properties to palladium-based catalysts. In addition, the price of ruthenium is nearly 10 times cheaper than that of palladium, which can greatly reduce the cost of the electrode. However, the reported ruthenium-based catalysts have a large metal loading (about 2 mg / cm 2 ), and the utilization rate of ruthenium atoms is low. There is no report on ruthenium-based cathode materials, especially ultra-low ruthenium loading cathode materials, for electrocatalytic reduction of chlorinated organic compounds. Therefore, the prior art still needs to be improved and developed. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a porous cathode material with ultra-low ruthenium loading and a preparation method and application thereof, aiming to solve the problems of large metal loading and low ruthenium atom utilization rate of existing ruthenium-based catalysts.

[0006] The technical scheme of the present application is as follows:

[0007] A preparation method of a porous cathode material with ultra-low ruthenium loading, comprising the following steps:

[0008] The cobalt salt and the organic ligand are dissolved in a mixed solvent to prepare a mixed solution, the organic ligand is terephthalic acid or 2,6-naphthalene dicarboxylic acid, and the mixed solvent is composed of N,N-dimethylformamide, water and ethanol;

[0009] The pretreated electrode substrate is placed in the mixed solution, and a porous cathode material is prepared after reaction;

[0010] The porous cathode material is placed in a ruthenium salt solution, and the ultra-low ruthenium loading porous cathode material is prepared after reaction.

[0011] The preparation method of the ultra-low ruthenium loading porous cathode material, wherein the cobalt salt is one or more of cobalt chloride, cobalt nitrate and cobalt sulfate; and the concentration of the cobalt salt is 0.01-0.5 mol / L.

[0012] The preparation method of the ultra-low ruthenium loading porous cathode material, wherein the concentration of the organic ligand is 0.01-0.5 mol / L.

[0013] The preparation method of the ultra-low ruthenium loading porous cathode material, wherein in the mixed solvent, the volume ratio of N,N-dimethylformamide, water and ethanol is 1:(0.01-0.1):(0.01-0.1).

[0014] The preparation method of the ultra-low ruthenium loading porous cathode material, wherein the electrode substrate is foamed nickel, foamed titanium or carbon felt.

[0015] The preparation method of the ultra-low ruthenium loading porous cathode material, wherein in the step of placing the pretreated electrode substrate in the mixed solution and preparing the porous cathode material after reaction, the reaction temperature is 100-150 DEG C, and the reaction time is 5-24 h.

[0016] The preparation method of the ultra-low ruthenium loading porous cathode material, wherein the ruthenium salt solution is composed of a solvent and a ruthenium salt dissolved in the solvent, the ruthenium salt is one or more of ruthenium chloride, ruthenium nitrate and ruthenium sulfate; the solvent is N,N-dimethylformamide or ethanol; and the concentration of the ruthenium salt solution is 0.001-0.01 mol / L.

[0017] The preparation method of the ultra-low ruthenium loading porous cathode material, wherein in the step of placing the porous cathode material in a ruthenium salt solution and preparing the ultra-low ruthenium loading porous cathode material after reaction, the reaction temperature is 80-120 DEG C, and the reaction time is 12-48 h.

[0018] An ultra-low ruthenium loading porous cathode material, wherein the ultra-low ruthenium loading porous cathode material is prepared by the preparation method of the ultra-low ruthenium loading porous cathode material.

[0019] An application of an ultra-low ruthenium loading porous cathode material, wherein the ultra-low ruthenium loading porous cathode material is used for electrocatalytic reduction of chlorinated organic pollutants.

[0020] Beneficial effects: the application first grows uniform and highly dispersed porous cobalt-based nanosheets on an electrode substrate through in-situ self-assembly, significantly increases the electrode active area, promotes the mass transfer of chlorinated organic matter to the catalytically active sites, and provides a large number of sites for ruthenium atom loading; then realizes the loading of ruthenium atoms on the porous cobalt-based nanosheets through an ion exchange method, realizes the atomic dispersion of ruthenium on the nanosheets, and greatly improves the atomic utilization rate of ruthenium. The application realizes high reduction activity of chlorinated organic matter under the condition of ultra-low ruthenium loading through the coupling of porous nanostructure and atomically dispersed ruthenium active sites, greatly reduces the cost of the electrode, and has great application prospect in the field of chlorinated organic matter pollution treatment. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A preparation method flow chart of the ultra-low ruthenium loading porous cathode material provided by the application is shown in the figure.

[0022] Figure 2 A scanning electron microscope photo of the cathode material obtained in Example 1 of the application is shown in the figure.

[0023] Figure 3 An element distribution chart of the cathode material obtained in Example 1 of the application is shown in the figure.

[0024] Figure 4 A surface element content distribution chart of the cathode material obtained in Example 1 of the application is shown in the figure. DETAILED DESCRIPTION

[0025] The application provides an ultra-low ruthenium loading porous cathode material, a preparation method and application thereof. In order to make the purpose, technical scheme and effects of the application more clear and explicit, the application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the application and not to limit the application.

[0026] Please refer to Figure 1 , Figure 1 A preparation method flow chart of the ultra-low ruthenium loading porous cathode material provided by the application is shown in the figure, which includes the following steps:

[0027] S10, dissolving a cobalt salt and an organic ligand in a mixed solvent to prepare a mixed solution, wherein the organic ligand is terephthalic acid or 2,6-naphthalene dicarboxylic acid, and the mixed solvent is composed of N,N-dimethylformamide, water and ethanol;

[0028] S20, placing a pretreated electrode substrate in the mixed solution to prepare a porous cathode material after reaction;

[0029] S30, placing the porous cathode material in a ruthenium salt solution to prepare an ultra-low ruthenium loading porous cathode material after reaction.

[0030] Specifically, the present application first loads uniform size and highly dispersed porous cobalt-based nanosheets on the electrode substrate by in-situ self-assembly method, and then uniformly loads ruthenium atoms on the porous cobalt-based nanosheets by ion exchange. The porous nanosheets not only can significantly increase the active area of the cathode, but also can promote the mass transfer of chlorinated organic matter to the catalytically active sites, thereby significantly improving the atomic utilization rate of ruthenium. Then, the above-mentioned ultra-low ruthenium loading porous cathode material is coupled with the anode to carry out electrocatalytic reaction in an electrolytic cell separated by an ion exchange membrane, so as to realize efficient reduction of chlorinated organic matter. The present application can solve the problem of high cost of electrode caused by high noble metal loading of existing cathode materials for electrocatalytic reduction of chlorinated organic matter, thereby greatly reducing the cost of pollutant treatment.

[0031] In some embodiments, the electrode substrate is a nickel foam, a titanium foam or a carbon felt, but is not limited thereto. The electrode substrate needs to be pretreated before the reaction. Specifically, the electrode substrate is ultrasonically cleaned in a 0.005-0.01 mol / L sulfuric acid solution for 0.5-1 h, then ultrasonically cleaned with acetone or ethanol for 0.5-1 h, and finally cleaned with ultrapure water until no acetone or ethanol residue is left, for standby use.

[0032] In some embodiments, the cobalt salt is one or more of cobalt chloride, cobalt nitrate and cobalt sulfate; and the concentration of the nickel salt is 0.01-0.5 mol / L, preferably 0.25 mol / L.

[0033] In some embodiments, the concentration of the organic ligand is 0.01-0.5 mol / L, preferably 0.25 mol / L.

[0034] In some embodiments, in the mixed solvent, the volume ratio of N,N-dimethylformamide, water and ethanol is 1:(0.01-0.1):(0.01-0.1), preferably 1:0.05:0.05.

[0035] In some embodiments, in the step of placing the pretreated electrode substrate in the mixed solution and preparing the porous cathode material after the reaction, the reaction temperature is 100-150℃, and the reaction time is 5-24 h.

[0036] In some embodiments, the ruthenium salt solution is composed of a solvent and a ruthenium salt dissolved in the solvent, the ruthenium salt is one or more of ruthenium chloride, ruthenium nitrate and ruthenium sulfate, but is not limited thereto; the solvent is N,N-dimethylformamide or ethanol; and the concentration of the ruthenium salt solution is 0.001-0.01 mol / L.

[0037] In some embodiments, in the step of placing the porous cathode material in the ruthenium salt solution and preparing the ultra-low ruthenium loading porous cathode material after the reaction, the reaction temperature is 80-120℃, and the reaction time is 12-48 h.

[0038] In some embodiments, an ultra-low ruthenium loading porous cathode material is also provided, wherein the ultra-low ruthenium loading porous cathode material is prepared by the preparation method of the ultra-low ruthenium loading porous cathode material.

[0039] The present application first grows uniform and highly dispersed porous cobalt-based nanosheets on the electrode substrate through in-situ self-assembly, significantly increases the electrode active area, promotes the mass transfer of chlorinated organic matter to the catalytically active sites, and provides a large number of sites for ruthenium atom loading; then realizes the loading of ruthenium atoms on the porous cobalt-based nanosheets through ion exchange method, realizes the atomic dispersion of ruthenium on the nanosheets, and greatly improves the atomic utilization rate of ruthenium. The present application realizes high reduction activity of chlorinated organic pollutants under the condition of ultra-low ruthenium loading by coupling porous nanostructure and atomic dispersion ruthenium active sites, greatly reduces the cost of the electrode, and has great application prospect in the field of chlorinated organic pollutant treatment.

[0040] In some embodiments, an application of the ultra-low ruthenium loading porous cathode material is also provided, wherein the ultra-low ruthenium loading porous cathode material is used for electrocatalytic reduction of chlorinated organic pollutants.

[0041] The present application will be further explained and described by specific examples as follows:

[0042] Example 1

[0043] The present example provides a preparation method of an ultra-low ruthenium loading porous cathode material: foam nickel (2cm*4cm*1mm) is soaked and cleaned in 0.01mol / L hydrochloric acid solution for 10 minutes, then cleaned with anhydrous ethanol for 10 minutes, and finally cleaned with pure water for 10 minutes for standby; 5mmol of cobalt nitrate hexahydrate and 5mmol of terephthalic acid are dissolved in 18mL of a mixed solvent of N,N-dimethylformamide, 1mL of ethanol and 1mL of water, and the pretreated foam nickel is added, and reacted at 130℃ for 5 hours, and then naturally cooled to room temperature; the electrode is taken out, first cleaned with N,N-dimethylformamide, and then cleaned with ethanol to obtain a porous cathode material; 18mg of ruthenium trichloride hydrate is dissolved in 18mL of ethanol, and the porous cathode material is added, and reacted at 80℃ for 12 hours, and then naturally cooled to room temperature; the electrode is taken out, first cleaned with ethanol for 10 minutes, then cleaned with pure water for 10 minutes, and finally dried at 80℃ to obtain an ultra-low ruthenium loading porous cathode material.

[0044] As shown in FIG. 1, the morphology of the porous cathode material obtained in the present example is that uniform and highly dispersed porous nanosheets are loaded on the foam nickel skeleton, which indicates that a uniform porous nanostructure is formed after in-situ self-assembly. Figure 2 Figure 3 ​The elemental distribution diagram shows that ruthenium is uniformly dispersed on the nanosheets, indicating that ion exchange achieved uniform loading of ruthenium atoms on the porous nanosheets; (See attached image) Figure 4 The elemental composition distribution proves that this cathode material has an ultra-low ruthenium loading (~0.05 g / m³). 2 ).

[0045] This embodiment also provides the application of the prepared ultra-low ruthenium loading porous cathode material to the electrocatalytic reduction of chloramphenicol and p-chlorophenol: using the obtained cathode material as the cathode, platinum wire as the anode, Nafion 117 ion exchange membrane as the diaphragm, and a silver / silver chloride electrode as the reference electrode, a three-electrode system was used for electrocatalysis at a constant voltage of -1.2V vs. Ag / AgCl for 30 minutes; wherein the concentration of chloramphenicol or p-chlorophenol was 100 mg / L, the electrolyte in the cathode chamber was 0.1 mol / L Na2SO4 solution, and the electrolyte in the anode chamber was 0.1 mol / L Na2SO4 solution, with a solution volume of 30 mL for both. The effect of the cathode material obtained in this embodiment on the electrocatalytic reduction of chloramphenicol or p-chlorophenol is shown in Table 1.

[0046] Example 2

[0047] This embodiment provides a method for preparing an ultra-low ruthenium loading porous cathode material: Nickel foam (2.2cm*4.3cm*1mm) is immersed in 0.01mol / L hydrochloric acid solution for 10 minutes, then rinsed with anhydrous ethanol for 10 minutes, and finally rinsed with pure water for 10 minutes for later use; 10mmol of cobalt nitrate hexahydrate and 10mmol of terephthalic acid are dissolved in 18mL... Pretreated nickel foam was added to a mixture of N,N-dimethylformamide, 1 mL ethanol, and 1 mL water. The mixture was reacted at 130 °C for 10 hours, then allowed to cool naturally to room temperature. The electrode was removed, cleaned first with N,N-dimethylformamide, and then with ethanol to obtain a porous cathode material. 9 mg of ruthenium trichloride hydrate was dissolved in 18 mL ethanol and added to an electrode loaded with porous cobalt-based nanosheets. The mixture was reacted at 90 °C for 12 hours, then allowed to cool naturally to room temperature. The electrode was removed, cleaned first with ethanol for 10 minutes, then with pure water for 10 minutes, and finally dried at 80 °C to obtain an ultra-low ruthenium loading porous cathode material with a ruthenium loading of ~0.02 g / m³. 2 .

[0048] This embodiment also provides the application of the ultra-low ruthenium loading porous cathode material prepared above: the application of this cathode material is the same as in Example 1. The effect of the cathode material obtained in this embodiment on the electrocatalytic reduction of chloramphenicol or p-chlorophenol is shown in Table 1.

[0049] Example 3

[0050] The embodiment provides a preparation method of a porous cathode material with an ultralow ruthenium loading: foam nickel (2.2 cm*4.3 cm*1 mm) is placed in a 0.01 mol / L hydrochloric acid solution for soaking and cleaning for 10 minutes, then is cleaned with anhydrous ethanol for 10 minutes, and finally is cleaned with pure water for 10 minutes for standby; 6 mmol of cobalt nitrate hexahydrate and 6 mmol of terephthalic acid are dissolved in a mixture of 18 mL of N,N-dimethylformamide, 1 mL of ethanol and 1 mL of water, the pretreated foam nickel is added, and reaction is carried out at 130 DEG C for 8 hours, and the electrode is taken out after natural cooling to room temperature, and the porous cathode material is obtained by cleaning with N,N-dimethylformamide and then with ethanol; 36 mg of ruthenium trichloride hydrate is dissolved in 18 mL of ethanol, and the electrode loaded with the porous cobalt-based nanosheet is added, and reaction is carried out at 100 DEG C for 12 hours, and the electrode is taken out after natural cooling to room temperature, and the porous cathode material with an ultralow ruthenium loading is obtained by cleaning with ethanol for 10 minutes, cleaning with pure water for 10 minutes and finally drying at 80 DEG C, and the ruthenium loading is about 0.12 g / m 2 .

[0051] The embodiment also provides an application of the prepared porous cathode material with an ultralow ruthenium loading: the application of the catalyst is the same as that in the embodiment 1. The effect of the cathode material obtained in the embodiment on electrocatalytic reduction of chloramphenicol or p-chlorophenol is shown in Table 1.

[0052] Comparative example 1

[0053] The comparative example provides a preparation method of a porous cathode material with an ultralow ruthenium loading: the preparation method of the electrode is basically the same as that in the embodiment 1, and the only difference is that the amount of ruthenium trichloride hydrate added is 0.

[0054] The comparative example also provides an application of the prepared porous cathode material with an ultralow ruthenium loading: the application of the electrode is the same as that in the embodiment 1. The effect of the electrode obtained in the comparative example on electrocatalytic reduction of chloramphenicol or p-chlorophenol is shown in Table 1.

[0055] Table 1 is the removal rate of chlorinated organic compounds in the embodiment 1-3 and the comparative example 1.

[0056]

[0057] As shown in Table 1, under the same voltage and temperature conditions, the removal rate of chlorinated organic compounds in the embodiment 1-3 is obviously higher than that in the comparative example 1. This shows that the coupling of the porous nanometer structure and the atomically dispersed ruthenium active site realizes high reduction activity of chlorinated organic compounds under the condition of an ultralow ruthenium loading, and greatly improves the atomic utilization rate of ruthenium.

[0058] It is to be understood that the application is not limited to the examples described above, which can be modified or adapted in several ways by those skilled in the art without departing from the scope of the present application, as defined by the appended claims.

Claims

1. A method for preparing an ultra-low ruthenium loading porous cathode material, characterized in that, Including the following steps: A mixed solution is prepared by dissolving cobalt salt and an organic ligand in a mixed solvent, wherein the organic ligand is terephthalic acid or 2,6-naphthalenedicarboxylic acid, and the mixed solvent is composed of N,N-dimethylformamide, water and ethanol. The pretreated electrode substrate is placed in the mixed solution, and a porous cathode material is prepared after the reaction. The porous cathode material was reacted in a ruthenium salt solution, and ruthenium atoms were loaded onto the porous cobalt-based nanosheets by ion exchange, achieving atomic-level dispersion of ruthenium on the nanosheets. After the reaction, an ultra-low ruthenium loading porous cathode material was obtained. The reaction temperature was 80-120℃ and the reaction time was 12-48h. The concentration of the ruthenium salt solution is 0.001-0.01 mol / L.

2. The method for preparing the ultra-low ruthenium loading porous cathode material according to claim 1, characterized in that, The cobalt salt is one or more of cobalt chloride, cobalt nitrate, and cobalt sulfate; the concentration of the cobalt salt is 0.01-0.5 mol / L.

3. The method for preparing the ultra-low ruthenium loading porous cathode material according to claim 1, characterized in that, The concentration of the organic ligand is 0.01-0.5 mol / L.

4. The method for preparing the ultra-low ruthenium loading porous cathode material according to claim 1, characterized in that, In the mixed solvent, the volume ratio of N,N-dimethylformamide, water and ethanol is 1:(0.01-0.1):(0.01-0.1).

5. The method for preparing the ultra-low ruthenium loading porous cathode material according to claim 1, characterized in that, The electrode substrate is nickel foam, titanium foam, or carbon felt.

6. The method for preparing the ultra-low ruthenium loading porous cathode material according to claim 1, characterized in that, In the step of placing the pretreated electrode substrate in the mixed solution and reacting to prepare a porous cathode material, the reaction temperature is 100-150℃ and the reaction time is 5-24h.

7. The method for preparing the ultra-low ruthenium loading porous cathode material according to claim 1, characterized in that, The ruthenium salt solution consists of a solvent and a ruthenium salt dissolved in the solvent, wherein the ruthenium salt is one or more of ruthenium chloride, ruthenium nitrate, and ruthenium sulfate; and the solvent is N,N-dimethylformamide or ethanol.

8. A porous cathode material with ultra-low ruthenium loading, characterized in that, The material was prepared using the method described in any one of claims 1-7 for the preparation of the ultra-low ruthenium loading porous cathode material.

9. An application of a porous cathode material with ultra-low ruthenium loading, characterized in that, The ultra-low ruthenium loading porous cathode material described in claim 8 is used for the electrocatalytic reduction of chlorinated organic pollutants.

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