Method for preparing zinc-doped cobalt selenide catalyst

Abstract

The present invention belongs to the field of functional materials. Provided is a method for preparing a zinc-doped cobalt selenide catalyst. The method for preparing a zinc-doped cobalt selenide catalyst comprises: adding a selenium powder to a potassium hydroxide solution, stirring same until the selenium powder is dissolved, then adding deionized water, cobalt nitrate, zinc nitrate and ethylenediaminetetraacetic acid disodium salt to the resulting solution, continuing stirring, putting the finally obtained solution into a polytetrafluoroethylene reaction kettle for a hydrothermal reaction, and after the reaction is finished, cooling the resulting reaction product to room temperature and then washing, drying and grinding same, so as to obtain a zinc-doped cobalt selenide catalyst. In the method for preparing a zinc-doped cobalt selenide catalyst provided by the present invention, during the preparation process, the raw materials are readily available, the reaction conditions are mild, and a zinc-doped cobalt selenide catalyst can be obtained at a relatively low temperature, all of which are beneficial for reducing the production cost. The zinc-doped cobalt selenide catalyst prepared in the present invention has a unique rod-like structure and good electro-catalytic performance, and the obtained electrocatalyst is non-toxic and harmless, and has wide application prospects.

Description

Preparation method of zinc-doped cobalt selenide catalyst Technical Field

[0001] The invention belongs to the field of functional materials, and particularly relates to a method for preparing a zinc-doped cobalt selenide catalyst. Background Art

[0002] With the development of modern society, energy crisis and environmental problems have aroused people's attention to clean and renewable energy. Hydrogen is an environmentally friendly renewable energy and is considered to be one of the most promising candidates for solving the current energy crisis and environmental problems. With the research in recent years, the development of electrochemical water splitting technology has attracted widespread attention. Catalysts with excellent hydrogen evolution activity are crucial for electrochemical water splitting. Precious metals are considered to be ideal catalytic materials due to their excellent hydrogen evolution reaction (HER) kinetics. However, their high cost and scarcity of raw materials limit their large-scale application in industry. Therefore, designing and synthesizing a low-cost, earth-abundant, efficient and stable HER catalyst has become the research focus of many scientific researchers.

[0003] Cobalt selenide, a member of the transition metal chalcogenide family, has been extensively studied as a HER electrocatalyst due to its unique electronic structure and chemical properties. However, the electrocatalytic active sites of cobalt selenide are located at the edges of the material and have a low density. Therefore, it is necessary to modify the edge structure to expose more active sites and thus improve its catalytic performance.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a zinc-doped cobalt selenide catalytic material with simple process and environmental friendliness.

[0006] To achieve the above object, the present invention provides a method for preparing a zinc-doped cobalt selenide catalyst, wherein a zinc-doped cobalt selenide catalyst having a rod-like structure and a length of about 100-600 nm is prepared by a hydrothermal method; the method comprises the following steps:

[0007] Step S1: adding selenium powder to potassium hydroxide solution and stirring until the selenium powder is dissolved to obtain solution A;

[0008] Step S2: adding a certain amount of deionized water to solution A to obtain solution B. Adding cobalt nitrate, disodium ethylenediaminetetraacetic acid, and zinc nitrate to solution B and stirring until dissolved to obtain solution C;

[0009] Step S3: Transfer solution C to a polytetrafluoroethylene-lined reactor and react at a certain temperature for several hours. After the reaction is completed, cool to room temperature, wash, dry, and grind to obtain a zinc-doped cobalt selenide catalyst.

[0010] Furthermore, in step S1, the concentration of the potassium hydroxide solution is 20 mol / L, the volume of the potassium hydroxide solution is 5-7 mL, and the concentration of selenium powder in the solution is 3-4 mol / L;

[0011] Furthermore, in step S2, the volume of the deionized water is 20-25 mL, the cobalt nitrate is cobalt nitrate hexahydrate, and the zinc nitrate is zinc nitrate hexahydrate. The molecular weight of the disodium edetate is 336. The molar ratio of the cobalt nitrate hexahydrate, disodium edetate, and zinc nitrate hexahydrate is 1:1.6-2.5:0.5-3.

[0012] Furthermore, in step S3, the hydrothermal reaction temperature is 180-200° C., the reaction time is 16-20 h, the vacuum drying temperature is 40-60° C., and the drying time is 12-24 h.

[0013] An application of the zinc-doped cobalt selenide catalyst prepared by the above preparation method in electrocatalytic hydrogen production.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) Raw materials are readily available during the preparation process of the present invention, which is beneficial to reducing production costs.

[0016] (2) The reaction conditions are mild, and the preparation of zinc-doped cobalt selenide electrocatalysts can be completed at a lower temperature.

[0017] (3) The zinc-doped cobalt selenide electrocatalyst prepared by the present invention has a unique rod-like structure and excellent electrocatalytic performance. The obtained catalyst is non-toxic and harmless and has broad application prospects.

[0018] (4) The present invention has low production cost, simple process, mild reaction conditions and is conducive to the sustainable development of the environment and energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG1 is a SEM image of a pure cobalt selenide catalyst;

[0020] FIG2 is a SEM image of Example 1;

[0021] FIG3 is an X-ray diffraction pattern of Example 1;

[0022] FIG4 is a linear sweep voltammetry graph of Example 1, Example 2, Example 3 and Example 4;

[0023] FIG5 is a cyclic voltammogram of Example 1;

[0024] FIG6 is an impedance diagram of Example 1;

[0025] FIG7 is a process flow chart of the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described below with reference to the accompanying drawings and examples, but is not limited thereto. Any modification or equivalent substitution of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be included in the scope of protection of the present invention. All raw materials were analytically pure.

[0027] The principle of the invention is that zinc ions are introduced through a simple hydrothermal method, replacing some of the cobalt ions in CoSe2. Zinc doping induces the formation of Se defects in CoSe2, adjusts the electronic structure, promotes the formation of the 1T phase, and activates the in-plane sites of the 1T phase CoSe2, thereby increasing both the density and intrinsic activity of the active sites. Zn doping also increases the electrochemical specific surface area of ​​CoSe2 and improves its stability.

[0028] Example 1:

[0029] Step 1: Add 0.158 g of selenium powder to 5 mL of 20 mol / L potassium hydroxide solution and stir for 40 min until the selenium powder is dissolved to obtain solution A.

[0030] Step 2: Add cobalt nitrate hexahydrate, disodium ethylenediaminetetraacetate, zinc nitrate hexahydrate, and 20 mL of deionized water to solution A and stir for 1 hour to obtain solution B, wherein the molar ratio of cobalt nitrate hexahydrate, disodium ethylenediaminetetraacetate, and zinc nitrate hexahydrate is 1:1.6:1;

[0031] Step 3: Solution B was transferred to a reactor and reacted at a hydrothermal temperature of 180°C for 16 hours. The precipitate obtained after the reaction was washed with deionized water and anhydrous ethanol, and dried at 60°C for 12 hours to obtain a zinc-doped cobalt selenide catalyst.

[0032] Example 2:

[0033] Step 1: Add 0.158 g of selenium powder to 5 mL of 20 mol / L potassium hydroxide solution and stir for 40 min until the selenium powder is dissolved to obtain solution A.

[0034] Step 2: Add cobalt nitrate hexahydrate, disodium ethylenediaminetetraacetate, zinc nitrate hexahydrate, and 20 mL of deionized water to solution A and stir for 1 hour to obtain solution B, wherein the molar ratio of cobalt nitrate hexahydrate, disodium ethylenediaminetetraacetate, and zinc nitrate hexahydrate is 1:1.6:2;

[0035] Step 3: Solution B was transferred to a reactor and reacted at a hydrothermal temperature of 180°C for 16 hours. The precipitate obtained after the reaction was washed with deionized water and anhydrous ethanol, and dried at 60°C for 12 hours to obtain a zinc-doped cobalt selenide catalyst.

[0036] Example 3:

[0037] Step 1: Add 0.158 g of selenium powder to 5 mL of 20 mol / L potassium hydroxide solution and stir for 40 min until the selenium powder is dissolved to obtain solution A.

[0038] Step 2: Add cobalt nitrate hexahydrate, disodium ethylenediaminetetraacetate, zinc nitrate hexahydrate, and 20 mL of deionized water to solution A and stir for 1 hour to obtain solution B, wherein the molar ratio of cobalt nitrate hexahydrate, disodium ethylenediaminetetraacetate, and zinc nitrate hexahydrate is 1:1.6:0.5;

[0039] Step 3: Solution B was transferred to a reactor and reacted at a hydrothermal temperature of 180°C for 16 hours. The precipitate obtained after the reaction was washed with deionized water and anhydrous ethanol, and dried at 60°C for 12 hours to obtain a zinc-doped cobalt selenide catalyst.

[0040] Example 4:

[0041] Step 1: Add 0.158 g of selenium powder to 5 mL of 20 mol / L potassium hydroxide solution and stir for 40 min until the selenium powder is dissolved to obtain solution A.

[0042] Step 2: Add cobalt nitrate hexahydrate, disodium ethylenediaminetetraacetate, zinc nitrate hexahydrate, and 20 mL of deionized water to solution A and stir for 1 hour to obtain solution B, wherein the molar ratio of cobalt nitrate hexahydrate, disodium ethylenediaminetetraacetate, and zinc nitrate hexahydrate is 1:1.6:3;

[0043] Step 3: Solution B was transferred to a reactor and reacted at a hydrothermal temperature of 180°C for 16 hours. The precipitate obtained after the reaction was washed with deionized water and anhydrous ethanol, and dried at 60°C for 12 hours to obtain a zinc-doped cobalt selenide catalyst.

[0044] Example 5:

[0045] Step 1: Add 0.158 g of selenium powder to 5 mL of 20 mol / L potassium hydroxide solution and stir for 40 min until the selenium powder is dissolved to obtain solution A.

[0046] Step 2: Add cobalt nitrate hexahydrate, disodium ethylenediaminetetraacetate, zinc nitrate hexahydrate, and 20 mL of deionized water to solution A and stir for 1 hour to obtain solution B, wherein the molar ratio of cobalt nitrate hexahydrate, disodium ethylenediaminetetraacetate, and zinc nitrate hexahydrate is 1:2:2.5;

[0047] Step 3: Solution B was transferred to a reactor and reacted at a hydrothermal temperature of 180°C for 18 hours. The precipitate obtained after the reaction was washed with deionized water and anhydrous ethanol, and dried at 60°C for 12 hours to obtain a zinc-doped cobalt selenide catalyst.

[0048] Example 6:

[0049] Step 1: Add 0.158 g of selenium powder to 5 mL of 20 mol / L potassium hydroxide solution and stir for 40 min until the selenium powder is dissolved to obtain solution A.

[0050] Step 2: Add cobalt nitrate hexahydrate, disodium ethylenediaminetetraacetate, zinc nitrate hexahydrate, and 20 mL of deionized water to solution A and stir for 1 hour to obtain solution B, wherein the molar ratio of cobalt nitrate hexahydrate, disodium ethylenediaminetetraacetate, and zinc nitrate hexahydrate is 1:1.6:2;

[0051] Step 3: Solution B was transferred to a reactor and reacted at a hydrothermal temperature of 180°C for 20 hours. The precipitate obtained after the reaction was washed with deionized water and anhydrous ethanol, and dried at 60°C for 12 hours to obtain a zinc-doped cobalt selenide catalyst.

[0052] Experimental Example 1:

[0053] X-ray diffraction analysis was performed on Example 1 and the cobalt selenide material, and their micromorphologies were observed using a scanning electron microscope.

[0054] As shown in Figures 1 and 2, the microstructure of pure cobalt selenide is an irregular flaky structure with agglomeration. The microstructure of zinc-doped cobalt selenide prepared in Example 1 has changed, with a rod-like structure and uniform dispersion, which provides a possibility for increasing edge active sites.

[0055] As shown in Figure 3, compared to pure cobalt selenide, zinc doping reveals significant changes in the XRD pattern. Comparison of the XRD diffraction patterns of Example 1 and pure cobalt selenide reveals that the characteristic peaks of zinc-doped cobalt selenide at 35.8° and 47.6° shift toward smaller diffraction angles, indicating successful zinc doping into the cobalt selenide lattice. Furthermore, while maintaining the original cobalt selenide peaks, Example 1 exhibits new diffraction peaks at 28.53° and 56.30°. Comparison with a standard PDF card reveals the formation of zinc selenide in Example 1, indicating the creation of new crystal planes.

[0056] Experimental Example 2:

[0057] As shown in Figure 4, at a current density of 10 mA / cm 2 When the overpotential of Example 1 is 234 mV, the overpotentials of the other three examples are all higher than that of Example 1, which shows that the electrochemical performance of Example 1 is the best. It also shows that zinc doping affects the activity of the catalyst.

[0058] As shown in Figure 5, during the electrocatalytic hydrogen evolution reaction, the catalytic activity of a catalyst is determined by its electrochemically active surface area. Generally speaking, the electrochemically active surface area of ​​a sample is positively correlated with its double-layer capacitance. Cyclic voltammetry curves of the zinc-doped cobalt selenide catalyst were measured at different scan rates (20, 40, 60, 80, 120, and 160 mV / s) within the non-Faraday potential range (+0.56 to +0.70).

[0059] To further investigate the effect of zinc doping on the catalytic activity of the cobalt selenide matrix, electrochemical impedance spectroscopy (EIS) was used to study the charge transfer mechanism, as shown in Figure 6. Charge transfer resistance (CTR) is an impedance that originates in the low-frequency region and governs the interfacial dynamics between the catalyst and the electrolyte. A smaller CT value indicates a higher charge transfer rate and a faster reaction rate.

[0060] The above content is only a basic description of the concept of the present invention. Any equivalent changes made to the technical solution of the present invention by reading the specification of the present invention shall fall within the scope of protection of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a zinc-doped cobalt selenide catalyst, characterized in that: The following steps are involved: Step S1: adding selenium powder to potassium hydroxide solution and stirring until the selenium powder is dissolved to obtain solution A; Step S2: adding a certain amount of deionized water to solution A to obtain solution B, adding cobalt nitrate, disodium ethylenediaminetetraacetate and zinc nitrate to solution B, stirring until dissolved, to obtain solution C; Step S3: Transfer solution C to a polytetrafluoroethylene-lined reactor and react at a certain temperature for several hours. After the reaction is completed, cool to room temperature, wash, vacuum dry, and grind to obtain a zinc-doped cobalt selenide catalyst.

2. The method for preparing a zinc-doped cobalt selenide catalyst according to claim 1, characterized in that: In step S1, the concentration of the potassium hydroxide solution is 20 mol / L, the volume of the potassium hydroxide solution is 5-7 mL, and the concentration of selenium powder in the solution is 3-4 mol / L.

3. The method for preparing a zinc-doped cobalt selenide catalyst according to claim 1, characterized in that: In step S2, the cobalt nitrate is cobalt nitrate hexahydrate, and the zinc nitrate is zinc nitrate hexahydrate; the molecular weight of the disodium ethylenediaminetetraacetic acid is 336; the molar ratio of the cobalt nitrate hexahydrate, the disodium ethylenediaminetetraacetic acid and the zinc nitrate hexahydrate is 1:1.6-2.5:0.5-3; and the volume of the deionized water is 20-25 mL.

4. The method for preparing a zinc-doped cobalt selenide catalyst according to claim 1, characterized in that: In step S3, the hydrothermal reaction temperature is 180-200°C, the reaction time is 16-20h, the vacuum drying temperature is 40-60°C, and the drying time is 12-24h.

5. Use of the zinc-doped cobalt selenide catalyst prepared by the preparation method according to any one of claims 1 to 4 in electrocatalytic hydrogen production.

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