Copper atom doped cobalt disulfide catalyst as well as preparation method and application thereof

Abstract

The invention discloses a copper atom-doped cobalt disulfide catalyst and a preparation method and application thereof, and belongs to the technical field of energy catalysis, the copper atom-doped cobalt disulfide catalyst comprises cobalt disulfide and copper atoms doped in the cobalt disulfide, and the doping mass fraction of the copper atoms is 1-5wt%. The preparation method comprises the following steps: dissolving cobalt salt and copper salt in deionized water to obtain a mixed solution A; dissolving sodium sulfide nonahydrate in deionized water to obtain a solution B; dropwise adding the solution B into the mixed solution A in a stirring state, washing and drying an obtained black precipitate C, uniformly mixing the black precipitate C with sulfur powder, and calcining in an argon atmosphere to obtain the product. Copper atoms are doped in cobalt disulfide, the monatomic catalyst is prepared, the electro-catalytic performance of cobalt disulfide is optimized, high selectivity in the reaction for preparing hydrogen peroxide through acid electrochemical oxygen reduction is achieved, and the preparation method is novel, simple, controllable, easy to achieve and suitable for large-scale production and application.

Description

Technical Field

[0001] The invention belongs to the technical field of energy catalysis, and specifically relates to a copper atom-doped cobalt disulfide catalyst and a preparation method and application thereof. Background Art

[0002] As a green chemical product, hydrogen peroxide can be used in electronics, medical and other fields. However, the current synthesis of hydrogen peroxide mainly relies on the anthraquinone process, which produces a large amount of pollutants and has a complex separation procedure. It not only consumes energy but also causes environmental pollution. Therefore, it is very important to develop a green and environmentally friendly method for synthesizing hydrogen peroxide. Using water and oxygen as raw materials, synthesizing hydrogen peroxide through electrochemical oxygen reduction reaction can effectively avoid energy consumption and environmental pollution. At present, the catalysts used for electrochemical oxygen reduction synthesis of hydrogen peroxide mainly include precious metals and their alloys, compounds, transition metal single atoms, and carbon-based materials. Among them, carbon materials are the most studied. Due to their advantages such as easy structure regulation, large specific surface area, rich surface defects and low price, they are widely used to synthesize hydrogen peroxide under alkaline conditions. However, hydrogen peroxide under alkaline conditions is unstable and easily decomposed.

[0003] In contrast, hydrogen peroxide is more stable under acidic conditions, less prone to decomposition, and more oxidizing. In addition, proton exchange membranes used under acidic conditions are more widely studied and have good stability and ionic conductivity. However, most catalysts used under acidic conditions are precious metal materials, which are expensive and have disadvantages such as the toxicity of some metals, which limit their widespread application. Compared with precious metal materials, transition metal sulfides, which are abundant on Earth, can not only better disperse metal active sites, but also provide more structural elements that are easy to regulate on the surface, which has great potential for improving the activity and selectivity of two-electron oxygen reduction reactions under acidic conditions.

[0004] Transition metal sulfides have attracted extensive attention due to their unique structural features, abundant active sites, tunable electronic properties, and composition. 2 ) is a quasi-metal material with excellent electron conduction ability and is widely used in the field of electrocatalysis. However, its catalytic performance is limited. Some studies (Electrocatalytic Production of H 2 O 2 bySelective Oxygen Reduction Using Earth-Abundant Cobalt Pyrite(CoS 2 )) shows that CoS 2 H 2 O 2 The selectivity is less than 80%. Therefore, it is necessary to optimize the electrocatalytic performance of cobalt disulfide through regulation to improve the selectivity of hydrogen peroxide. Summary of the invention

[0005] In view of the low selectivity of existing cobalt disulfide catalysts for hydrogen peroxide, the present invention provides a copper atom-doped cobalt disulfide catalyst and a preparation method and application thereof, which has high hydrogen peroxide selectivity in the acidic electrochemical oxygen reduction reaction for synthesizing hydrogen peroxide, has a simple preparation method, and is suitable for wide application.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A copper atom-doped cobalt disulfide catalyst comprises cobalt disulfide and copper atoms doped in the cobalt disulfide, wherein the doping mass fraction of the copper atoms is 1-5wt%.

[0008] A method for preparing a copper atom-doped cobalt disulfide catalyst comprises the following steps:

[0009] Step 1, dissolving cobalt salt and copper salt in deionized water to obtain a mixed solution A;

[0010] Step 2, dissolving sodium sulfide nonahydrate in deionized water to obtain solution B;

[0011] Step 3, drop solution B into the stirred mixed solution A to obtain a black precipitate C;

[0012] Step 4: Wash and dry the black precipitate C, mix it evenly with sulfur powder, and calcine it under an argon atmosphere to obtain a copper atom-doped cobalt disulfide catalyst.

[0013] Furthermore, in step 1, the cobalt salt is cobalt nitrate hexahydrate or cobalt chloride hexahydrate, and the copper salt is hydrated copper nitrate or copper nitrate trihydrate.

[0014] Furthermore, the concentration of cobalt ions in the mixed solution A is 0.15-0.175 g / mL, wherein the molar ratio of cobalt ions to copper ions is 10-12:0.15-0.82.

[0015] Furthermore, the solute concentration in the solution B is 0.125-0.140 g / mL.

[0016] Furthermore, in the black precipitate C synthesized in step 3, the molar ratio of cobalt atoms to sulfur atoms is 10-12:10.4-12.

[0017] Furthermore, in step 3, the stirring speed is 300 to 800 rpm, and the stirring time is 1 to 5 hours.

[0018] Furthermore, the mass ratio of the dried black precipitate C to the sulfur powder in step 4 is 1:2.

[0019] Furthermore, the specific process of calcination in step 4 is: at an argon flow rate of 80-100 sccm, first calcining at 200-250°C for 3-8h, then calcining at 400-500°C for 0.5-1.5h, and the heating rate is 3-8°C / min.

[0020] Furthermore, the specific process of washing in step 4 is: first washing with deionized water for 3 to 5 times, then washing with anhydrous ethanol for 1 to 3 times, each time for 3 to 8 minutes, and the centrifugal speed of washing is 8000 to 10000 rpm.

[0021] Furthermore, the specific process of drying in step 4 is: drying in a vacuum oven at 60° C. for at least 12 hours.

[0022] The present invention also provides an application of the copper atom-doped cobalt disulfide catalyst described in any one of the above technical solutions or the copper atom-doped cobalt disulfide catalyst obtained by the preparation method described in any one of the above technical solutions in the acidic electrochemical oxygen reduction reaction for preparing hydrogen peroxide.

[0023] An acidic electrochemical oxygen reduction device for preparing hydrogen peroxide, using a conductive substrate loaded with a copper atom-doped cobalt disulfide catalyst as a working electrode, wherein the loading amount of the copper atom-doped cobalt disulfide catalyst is 0.8-1.2 mg / cm 2 .

[0024] Furthermore, the acidic electrochemical oxygen reduction device for preparing hydrogen peroxide is tested in a constant potential mode, with a potential range of 0 to 0.8 V (compared to a reversible hydrogen electrode).

[0025] Furthermore, the acidic electrochemical oxygen reduction device for preparing hydrogen peroxide is implemented based on an H-type electrolytic cell, and the electrolyte used is perchloric acid or sulfuric acid.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention proposes a copper atom-doped cobalt disulfide catalyst, a preparation method and an application thereof. Copper atoms are doped into cobalt disulfide to prepare a single-atom catalyst, so as to optimize the electrocatalytic performance of cobalt disulfide and achieve high selectivity in the reaction of preparing hydrogen peroxide by acidic electrochemical oxygen reduction. Meanwhile, the doping amount of copper atoms can be adjusted to obtain optimal electrocatalytic performance. The preparation method of the present invention is novel, simple and controllable, easy to implement and suitable for large-scale production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 X-ray diffraction diagrams of the cobalt disulfide catalysts doped with different amounts of copper atoms obtained in Examples 1 to 3 of the present invention and the cobalt disulfide catalyst obtained in Comparative Example 1;

[0030] Figure 2 The transmission electron microscope image and element distribution diagram of the cobalt disulfide catalyst obtained in Comparative Example 1 of the present invention;

[0031] Figure 3 The transmission electron microscope image and element distribution map of the 0.89 wt% copper atom-doped cobalt disulfide catalyst obtained in Example 1 of the present invention;

[0032] Figure 4 The transmission electron microscope image and element distribution map of the 2.60 wt% copper atom-doped cobalt disulfide catalyst obtained in Example 2 of the present invention;

[0033] Figure 5 The transmission electron microscope image and element distribution diagram of the 4.50 wt% copper atom-doped cobalt disulfide catalyst obtained in Example 3 of the present invention.

[0034] Figure 6 It is a schematic diagram of the structure of the H-type reactor used in Example 2 of the present invention and Comparative Example 1;

[0035] Figure 7 The Faraday efficiency of hydrogen peroxide at different potentials for the reaction of 2.60 wt% copper atom-doped cobalt disulfide catalyst obtained in Example 2 of the present invention and the cobalt disulfide catalyst obtained in Comparative Example 1 catalyzing acidic two-electron oxygen reduction to synthesize hydrogen peroxide in an H-type reactor. DETAILED DESCRIPTION

[0036] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention.

[0037] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0038] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably adopts analytically pure materials or materials with conventional purity requirements in the field of atomic layer deposition.

[0039] All raw materials and process steps of the present invention, their brands or abbreviations are conventional brands or abbreviations in the art, and each brand or abbreviation is clear and definite in the field of its related use. Those skilled in the art can purchase them from the market or prepare them by conventional methods, or implement them with corresponding equipment according to the brands, abbreviations and corresponding uses.

[0040] The present invention will be further described below in conjunction with embodiments:

[0041] Comparative Example 1

[0042] This comparative example prepares a cobalt disulfide catalyst, which specifically includes the following steps:

[0043] Step 1, dissolving 3.2 g of cobalt nitrate hexahydrate in 20 mL of deionized water to obtain a mixed solution A;

[0044] Step 2, dissolving 2.642 g of sodium sulfide nonahydrate in 20 mL of deionized water to obtain solution B;

[0045] Step 3, add solution B drop by drop into the stirred mixed solution A at a stirring speed of 500 rpm, stir and react for 3 hours to obtain a black precipitate C;

[0046] Step 4, washing the black precipitate C by centrifugation, specifically washing it 4 times in deionized water and then washing it once with anhydrous ethanol, each time for 5 minutes, and the centrifugal speed is 9000 rpm; then drying it in a vacuum oven at 60°C overnight;

[0047] Step 5: The dried black precipitate C and sulfur powder are mixed and ground evenly in a mass ratio of 1:2, and placed in a tubular furnace for calcination. Specifically, the mixture is first reacted at 230°C for 5 hours, then reacted at 450°C for 1 hour, the heating rate is 5°C / min, the argon flow rate is 100 sccm, and the mixture is cooled to room temperature after calcination to obtain a cobalt disulfide catalyst.

[0048] Example 1

[0049] This embodiment prepares a copper atom-doped cobalt disulfide catalyst, which specifically includes the following steps:

[0050] Step 1, dissolving 3.2 g of cobalt nitrate hexahydrate and 37 mg of copper nitrate hydrate in 20 mL of deionized water to obtain a mixed solution A;

[0051] Step 2, dissolving 2.642 g of sodium sulfide nonahydrate in 20 mL of deionized water to obtain solution B;

[0052] Step 3, add solution B drop by drop into the stirred mixed solution A at a stirring speed of 600 rpm, stir and react for 3 hours to obtain a black precipitate C;

[0053] Step 4, washing the black precipitate C by centrifugation, specifically washing it 4 times in deionized water and then washing it once with anhydrous ethanol, each time for 5 minutes, and the centrifugal speed is 9000 rpm; then drying it in a vacuum oven at 60°C overnight;

[0054] Step 5: The dried black precipitate C and sulfur powder are mixed and ground evenly in a mass ratio of 1:2, and placed in a tubular furnace for calcination. Specifically, the mixture is first reacted at 230°C for 5 hours, and then reacted at 450°C for 1 hour. The heating rate is 5°C / min. After calcination, the mixture is cooled to room temperature to obtain a copper atom-doped cobalt disulfide catalyst.

[0055] According to the detection of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), the doping mass fraction of copper atoms in the copper atom-doped cobalt disulfide catalyst obtained in this example is 0.89 wt %.

[0056] Example 2

[0057] In this embodiment, a copper atom-doped cobalt disulfide catalyst is prepared. The preparation process is different from that in Example 1, except that the addition amount of copper nitrate hydrate in step 1 is adjusted to 111 mg; the other preparation processes remain unchanged.

[0058] According to ICP-OES detection, the doping mass fraction of copper atoms in the copper atom-doped cobalt disulfide catalyst obtained in this example is 2.60 wt %.

[0059] Example 3

[0060] In this embodiment, a copper atom-doped cobalt disulfide catalyst is prepared. The preparation process is different from that in Example 1, except that the addition amount of copper nitrate hydrate in step 1 is adjusted to 185 mg; the other preparation processes remain unchanged.

[0061] According to ICP-OES detection, the doping mass fraction of copper atoms in the copper atom-doped cobalt disulfide catalyst obtained in this example is 4.50 wt %.

[0062] Figure 1 The X-ray diffraction patterns of the cobalt disulfide catalysts doped with different doping amounts of copper atoms obtained in Examples 1 to 3 and the cobalt disulfide catalyst obtained in Comparative Example 1 show that cobalt disulfide is successfully synthesized in Examples 1 to 3 and Comparative Example 1, and the doped copper atoms do not change the structure of cobalt disulfide.

[0063] Figure 2 The transmission electron microscope image and element distribution diagram of the cobalt disulfide catalyst obtained in Comparative Example 1 are shown in FIG. Figure 3 The transmission electron microscope image and element distribution diagram of the 1wt% copper atom-doped cobalt disulfide catalyst obtained in Example 1 are shown in FIG. Figure 4 The transmission electron microscope image and element distribution diagram of the 3wt% copper atom-doped cobalt disulfide catalyst obtained in Example 2 are shown in FIG. Figure 5 The transmission electron microscope image and element distribution diagram of the 5wt% copper atom-doped cobalt disulfide catalyst obtained in Example 3. Figure 2 to Figure 5 It can be seen that the cobalt disulfide catalyst obtained in Comparative Example 1 and the cobalt disulfide catalysts doped with different amounts of copper atoms obtained in Examples 1 to 3 are both in the form of particles with a size of 10 to 40 nanometers, and the copper doped in Examples 1 to 3 are independent of each other and do not agglomerate.

[0064] Example 4

[0065] Using an H-type reactor, the copper atom-doped cobalt disulfide catalyst obtained in Example 2 and the cobalt disulfide catalyst obtained in Comparative Example 1 were respectively tested for the acidic electrochemical oxygen reduction reaction to prepare hydrogen peroxide.

[0066] This embodiment specifically adopts a structure such as Figure 6 The H-type reactor shown is a glassy carbon electrode loaded with the copper atom-doped cobalt disulfide catalyst obtained in Example 2 or the cobalt disulfide catalyst obtained in Comparative Example 1 as the cathode (working electrode), a carbon rod as the anode (counter electrode), a silver / silver chloride electrode as the reference electrode, a proton exchange membrane, and a cathode electrolyte and an anolyte are both 0.1 mol / L perchloric acid, with a volume of 25 mL and an oxygen flow rate of 50 sccm. The test is conducted by a constant potential method, and the applied potential range is 0.2 to 0.7 volts (compared to a reversible hydrogen electrode). The obtained product is developed with titanium sulfate and detected by ultraviolet absorption spectroscopy, and the product concentration is calculated. Combined with the data of the electrochemical workstation, the Faraday efficiency of the product is obtained.

[0067] Figure 7 The Faraday efficiency of hydrogen peroxide at different potentials for the acidic two-electron oxygen reduction reaction of the cobalt disulfide catalyst doped with 2.60wt% copper atoms obtained in Example 2 and the cobalt disulfide catalyst obtained in Comparative Example 1 to synthesize hydrogen peroxide. It can be seen that after the cobalt disulfide catalyst is doped with 2.60wt% copper atoms, its Faraday efficiency of hydrogen peroxide is significantly improved, and it has excellent hydrogen peroxide selectivity.

[0068] Example 5

[0069] In this embodiment, a copper atom-doped cobalt disulfide catalyst is prepared. The preparation process is different from that in Example 1, except that the calcination treatment process in step 5 is adjusted to react at 200° C. for 8 h and then react at 400° C. for 1.5 h; the other preparation processes remain unchanged.

[0070] Example 6

[0071] In this embodiment, a copper atom-doped cobalt disulfide catalyst is prepared. The preparation process is different from that in Example 1, except that the calcination treatment process in step 5 is adjusted to react at 250° C. for 3 h and then react at 500° C. for 0.5 h; the other preparation processes remain unchanged.

[0072] Example 7

[0073] In this embodiment, a copper atom-doped cobalt disulfide catalyst is prepared. The preparation process is different from that in Example 1, except that the cobalt nitrate hexahydrate and the copper nitrate hydrate in step 1 are adjusted to cobalt chloride hexahydrate and copper nitrate trihydrate; the other preparation processes remain unchanged.

[0074] The above is a detailed introduction of a copper atom-doped cobalt disulfide catalyst and its preparation method and application proposed by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enables any technician in the field to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the textual expression of the claims, or if they include equivalent structural elements that are not substantially different from the textual expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A copper atom-doped cobalt disulfide catalyst, characterized in that: The invention comprises cobalt disulfide and copper atoms doped in the cobalt disulfide, wherein the doping mass fraction of the copper atoms is 1-5wt%.

2. A method for preparing a copper atom-doped cobalt disulfide catalyst, characterized in that: The following steps are involved: Step 1, dissolving cobalt salt and copper salt in deionized water to obtain a mixed solution A; Step 2, dissolving sodium sulfide nonahydrate in deionized water to obtain solution B; Step 3, drop solution B into the stirred mixed solution A to obtain a black precipitate C; Step 4: Wash and dry the black precipitate C, mix it evenly with sulfur powder, and calcine it under an argon atmosphere to obtain a copper atom-doped cobalt disulfide catalyst.

3. The method for preparing the copper atom-doped cobalt disulfide catalyst according to claim 2, characterized in that: In step 1, the cobalt salt is cobalt nitrate hexahydrate or cobalt chloride hexahydrate, and the copper salt is hydrated copper nitrate or copper nitrate trihydrate.

4. The method for preparing the copper atom-doped cobalt disulfide catalyst according to claim 2, characterized in that: The cobalt ion concentration in the mixed solution A is 0.15-0.175 g / mL, wherein the molar ratio of cobalt ions to copper ions is 10-12:0.15-0.

82.

5. The method for preparing the copper atom-doped cobalt disulfide catalyst according to claim 2, characterized in that: The solute concentration in the solution B is 0.125-0.140 g / mL.

6. The method for preparing the copper atom-doped cobalt disulfide catalyst according to claim 2, characterized in that: In the black precipitate C synthesized in step 3, the molar ratio of cobalt atoms to sulfur atoms is 10-12:10.4-12.

7. The method for preparing the copper atom-doped cobalt disulfide catalyst according to claim 2, characterized in that: The mass ratio of the dried black precipitate C to the sulfur powder in step 4 is 1:

2.

8. The method for preparing the copper atom-doped cobalt disulfide catalyst according to claim 2, characterized in that: The specific process of calcination in step 4 is: at an argon flow rate of 80-100 sccm, first calcine at 200-250°C for 3-8h, then calcine at 400-500°C for 0.5-1.5h, and the heating rate is 3-8°C / min.

9. Use of the copper atom-doped cobalt disulfide catalyst obtained by the method of any one of claims 2 to 8 in the acidic electrochemical oxygen reduction reaction for preparing hydrogen peroxide.

10. An acidic electrochemical oxygen reduction device for preparing hydrogen peroxide, characterized in that: A conductive substrate loaded with a copper atom-doped cobalt disulfide catalyst obtained by the method of any one of claims 2 to 8 is used as a working electrode, wherein the loading amount of the copper atom-doped cobalt disulfide catalyst is 0.8 to 1.2 mg / cm 2 .

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