RuO2 / Co3O4atNC difunctional electro-catalytic material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of electro-catalysis, and particularly relates to a RuO2 / Co3O4-coated NC bifunctional electro-catalysis material and a preparation method and application thereof.The electro-catalysis material is of a heterostructure formed by taking carbon cloth as a substrate and loading a nitrogen-doped carbon shell layer on the surface to wrap Co3O4 and RuO2. Meanwhile, the invention also provides a preparation method of the electro-catalytic material and application of the electro-catalytic material in electro-catalytic full-hydrolysis of water. According to the obtained RuO2 / Co3O4-coated NC bifunctional electrocatalyst, the electrocatalytic hydrogen evolution and oxygen evolution performance of a composite material can be improved, and the long-time operation stability of hydrogen evolution and oxygen evolution can also be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalysis, and specifically relates to a RuO2 / Co3O4@NC bifunctional electrocatalytic material and a preparation method and application thereof. Background Art

[0002] Developing sustainable and environmentally friendly renewable energy conversion technologies is one of the effective ways to address severe environmental challenges. Hydrogen is a clean, green alternative to fossil fuels. The development of water electrolysis for sustainable hydrogen production requires efficient and stable catalysts. Precious metals have high electrocatalytic activity for the HER and OER reactions, but this significantly increases the cost of hydrogen production from water electrolysis. Therefore, exploring low-cost, efficient, and stable HER and OER electrocatalysts is of great significance for promoting water electrolysis.

[0003] Ru is a relatively inexpensive and abundant metal, offering a promising alternative to Pt and Ir electrocatalysts. Although RuO2 has been extensively studied for electrocatalytic water splitting, it suffers from drawbacks such as poor OER activity and long-term stability in alkaline solutions, as well as low HER activity in both acidic and alkaline media. Therefore, the development of efficient RuO2-based electrocatalysts is needed to enhance both HER and OER performance.

[0004] By constructing a heterostructure with transition metal oxides, the electronic structure of RuO2 can be manipulated, increasing its oxygen binding energy and enhancing its electrocatalytic performance. However, transition metal oxides are prone to phase transformation in alkaline environments, causing structural instability in the catalyst. Constructing a protective layer (such as a carbon shell) to isolate it from the electrolyte can effectively stabilize the catalyst structure, thereby enhancing the structural stability of the composite material. Summary of the Invention

[0005] To solve the problems in the prior art of RuO2's poor OER activity and long-term stability in alkaline solutions, as well as its low HER activity in acidic or alkaline media, the present invention provides a RuO2 / Co3O4@NC bifunctional electrocatalytic material with high hydrogen and oxygen evolution performance, its preparation method, and application. The specific scheme is as follows:

[0006] A RuO2 / Co3O4@NC bifunctional electrocatalytic material comprises carbon cloth and nanosheets supported on the carbon cloth; the nanosheets comprise a heterogeneous structure consisting of Co3O4 particles wrapped by nitrogen-doped carbon nanotubes and RuO2 on the surface.

[0007] Furthermore, the thickness of the nanosheet is 2-20 nm, and the size of the Co3O4 particles is 3-10 nm.

[0008] A method for preparing the above-mentioned RuO2 / Co3O4@NC bifunctional electrocatalytic material is characterized by comprising the following steps:

[0009] S1. Dissolve cobalt salt in water and immerse the carbon cloth in the solution; dissolve dimethylimidazole in water and add it to the solution to react, wash, centrifuge, and dry to obtain ZIF-L-Co;

[0010] S2, cut the ZIF-L-Co into a porcelain boat and calcine it in an inert atmosphere. The obtained sample was soaked in dilute H2SO4 and dried to obtain Co@NC;

[0011] S3. Dissolve the ruthenium salt in a mixed solution of anhydrous ethanol and ultrapure water; drop the mixed solution onto Co@NC, dry it, and then calcine it in air to obtain a RuO2 / Co3O4@NC bifunctional electrocatalyst.

[0012] Furthermore, the cobalt salt in S1 is one of cobalt nitrate and cobalt acetate; and the molar ratio of the cobalt salt to dimethylimidazole is 1:8-12.

[0013] Furthermore, the reaction time in S1 is 3-6 hours.

[0014] Furthermore, the calcination in S2 includes: first calcining at 300-400°C for 1.5-2.5h, and then calcining at 700-800°C for 1.5-2.5h.

[0015] Furthermore, the ruthenium salt described in S3 includes ruthenium chloride.

[0016] Furthermore, the molar ratio of the ruthenium salt in S3 to the cobalt salt in S1 is 1.5 to 3:1.

[0017] Furthermore, the drying in S3 is carried out at 40-80° C.; and the calcining in S3 is carried out at 300-400° C. for 1.5-2.5 hours.

[0018] An application of the above-mentioned RuO2 / Co3O4@NC bifunctional electrocatalytic material in electrocatalytic hydrogen evolution and / or oxygen evolution.

[0019] By adopting the above scheme, the method of the present invention has the following advantages:

[0020] 1. The RuO2 / Co3O4@NC bifunctional electrocatalyst prepared by the present invention has excellent electrocatalytic hydrogen and oxygen evolution activities and has long-term operation stability.

[0021] 2. The heterogeneous structure constructed by RuO2 and Co3O4 of the present invention can effectively improve the performance of hydrogen and oxygen evolution of the composite material; the nitrogen-doped carbon shell wrapped on the surface effectively improves the long-term operation stability of hydrogen and oxygen evolution of the composite material.

[0022] 3. The preparation method of the present invention is simple, the raw materials are abundant and the price is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a scanning electron microscope image of the RuO2 / Co3O4@NC bifunctional electrocatalyst prepared in Example 1.

[0024] Figure 2 This is a high-resolution transmission electron microscopy image of the RuO2 / Co3O4@NC bifunctional electrocatalyst prepared in Example 1.

[0025] Figure 3 This is a graph showing the electrocatalytic hydrogen evolution performance of the RuO2 / Co3O4@NC bifunctional electrocatalyst prepared in Example 1.

[0026] Figure 4 This is a graph showing the electrocatalytic oxygen evolution performance of the RuO2 / Co3O4@NC bifunctional electrocatalyst prepared in Example 1. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0028] Example 1:

[0029] (1) 0.455 g of cobalt nitrate hexahydrate was dissolved in 5 mL of deionized water to obtain solution 1, and the carbon cloth was immersed in solution 1 for 1 hour. 1.026 g of dimethylimidazole was dissolved in 5 mL of deionized water to obtain solution 2, which was then added to solution 1 and reacted for 4 hours. The ZIF-L-Co was washed with deionized water and dried for 6 hours.

[0030] (2) The ZIF-L-Co prepared above was calcined at 350°C for 2 hours and then at 750°C for 2 hours under Ar atmosphere. Co@NC was obtained after soaking in 0.5M H2SO4 and drying at 60°C.

[0031] (3) Dissolve 0.78 g of ruthenium trichloride trihydrate in a mixture of 118.75 mL of anhydrous ethanol and 6.25 mL of ultrapure water and sonicate for 30 minutes. Add 0.1 mL of the mixture dropwise onto the Co@NC sample. After drying at 60°C, the sample is calcined in air at 350°C for 2 hours to obtain RuO2 / Co3O4@NC.

[0032] The scanning electron microscopy images of the prepared RuO2 / Co3O4@NC electrocatalyst are shown in Figure 2. Figure 1 As shown in the figure, it can be seen that the RuO2 / Co3O4@NC electrocatalyst prepared in Example 1 has nanosheets loaded on the carbon cloth, and the nanosheets have nitrogen-doped carbon nanotube morphology.

[0033] The high-resolution transmission electron microscopy image of the RuO2 / Co3O4@NC electrocatalyst prepared in Example 1 is shown in FIG. Figure 2 As shown, Figure 2 In the high-resolution transmission electron microscope image shown, the crystal plane with a lattice spacing of 0.28nm corresponds to the (220) of Co3O4, and the crystal plane with a lattice spacing of 0.32nm corresponds to the (110) of RuO2, where the surface of Co3O4 is wrapped by a carbon shell and forms a heterogeneous interface with RuO2.

[0034] Example 2:

[0035] (1) 0.455 g of cobalt nitrate hexahydrate was dissolved in 5 mL of deionized water to obtain solution 1, and the carbon cloth was immersed in solution 1 for 1 hour. 1.026 g of dimethylimidazole was dissolved in 5 mL of deionized water to obtain solution 2, which was then added to solution 1 and reacted for 3 hours. The ZIF-L-Co was washed with deionized water and dried for 6 hours.

[0036] (2) The ZIF-L-Co obtained above was calcined at 300°C for 2 hours and then at 700°C for 2 hours under Ar atmosphere. Co@NC was obtained after soaking in 0.5M H2SO4 and drying at 60°C.

[0037] (3) 0.68 g of ruthenium trichloride trihydrate was dissolved in a mixture of 118.75 mL of anhydrous ethanol and 6.25 mL of ultrapure water and sonicated for 30 minutes. 0.1 mL of the mixed solution was dropwise added to the Co@NC sample. The sample, dried at 60°C, was calcined in air at 300°C for 2 hours to obtain RuO2 / Co3O4@NC-1.

[0038] Example 3:

[0039] (1) 0.455 g of cobalt nitrate hexahydrate was dissolved in 5 mL of deionized water to obtain solution 1, and the carbon cloth was immersed in solution 1 for 1 hour. 1.026 g of dimethylimidazole was dissolved in 5 mL of deionized water to obtain solution 2, which was then added to solution 1 and reacted for 5 hours. The ZIF-L-Co was washed with deionized water and dried for 6 hours.

[0040] (2) The ZIF-L-Co obtained above was calcined at 400°C for 2 hours and then at 800°C for 2 hours under Ar atmosphere. Co@NC was obtained after soaking in 0.5M H2SO4 and drying at 60°C.

[0041] (3) 0.91 g of ruthenium trichloride trihydrate was dissolved in a mixture of 118.75 mL of anhydrous ethanol and 6.25 mL of ultrapure water and sonicated for 30 minutes. 0.1 mL of the mixed solution was dropwise added to the Co@NC sample. The sample, dried at 60°C, was calcined in air at 400°C for 2 hours to obtain RuO2 / Co3O4@NC-2.

[0042] Example sample test:

[0043] The comparison experiment of electrocatalytic oxygen evolution was carried out using commercial RuO2 and Example 1. The results are as follows Figure 3 As shown. Figure 3 It can be seen that at 10mAcm -2 At a current density of 1.5 wt %, the oxygen evolution overpotential of RuO2 / Co3O4@NC is much lower than that of commercial RuO2, showing excellent oxygen evolution activity.

[0044] The commercial Pt / C was used to conduct a comparative experiment on electrocatalytic hydrogen evolution with Example 1. The results are as follows: Figure 4 shown by Figure 4 It can be seen that at 20mAcm -2 At a current density of 1.5 GHz, the hydrogen evolution overpotential of RuO2 / Co3O4@NC is comparable to that of commercial Pt / C, demonstrating excellent hydrogen evolution activity.

[0045] Those skilled in the art can make various other corresponding changes and deformations based on the technical solutions and concepts described above, and all of these changes and deformations should fall within the scope of protection of the claims of the present invention.

Claims

1. A RuO2 / Co3O4@NC bifunctional electrocatalytic material, characterized in that: The invention comprises a carbon cloth and a nanosheet supported on the carbon cloth; the nanosheet comprises a heterogeneous structure consisting of Co3O4 particles wrapped by nitrogen-doped carbon nanotubes and RuO2 on the surface.

2. The RuO2 / Co3O4@NC bifunctional electrocatalytic material according to claim 1, characterized in that: The thickness of the nanosheet is 2-20 nm, and the size of the Co3O4 particles is 3-10 nm.

3. A method for preparing the RuO2 / Co3O4@NC bifunctional electrocatalytic material according to claim 1 or 2, characterized in that: The following steps are involved: S1. Dissolve the cobalt salt in water and immerse the carbon cloth in the solution; Dissolve dimethylimidazole in water, add it to the above solution for reaction, wash, centrifuge and dry to obtain ZIF-L-Co; S2, cut the ZIF-L-Co and put it into a porcelain boat, calcine it in an inert atmosphere, soak the obtained sample in dilute H2SO4, and dry it to obtain Co@NC; S3, dissolving the ruthenium salt in a mixed solution of anhydrous ethanol and ultrapure water; dropping the mixed solution onto Co@NC, drying it, and calcining it in air to obtain a RuO2 / Co3O4@NC bifunctional electrocatalyst.

4. The method for preparing the RuO2 / Co3O4@NC bifunctional electrocatalytic material according to claim 3, characterized in that: S1 The cobalt salt is one of cobalt nitrate and cobalt acetate; the molar ratio of the cobalt salt to dimethylimidazole is 1:8-12.

5. The method for preparing the RuO2 / Co3O4@NC bifunctional electrocatalytic material according to claim 3, characterized in that: The reaction time of S1 is 3-6h.

6. The method for preparing the RuO2 / Co3O4@NC bifunctional electrocatalytic material according to claim 3, characterized in that: S2 The calcination includes: first calcining at 300-400°C for 1.5-2.5h, and then calcining at 700-800°C for 1.5-2.5h.

7. The method for preparing the RuO2 / Co3O4@NC bifunctional electrocatalytic material according to claim 3, characterized in that: S3 The ruthenium salt includes ruthenium chloride.

8. The method for preparing the RuO2 / Co3O4@NC bifunctional electrocatalytic material according to claim 3, characterized in that: The molar ratio of the ruthenium salt in S3 to the cobalt salt in S1 is 1.5 to 3:

1.

9. The method for preparing the RuO2 / Co3O4@NC bifunctional electrocatalytic material according to claim 3, characterized in that: The drying in S3 is carried out at 40-80°C; the calcination in S3 is carried out at 300-400°C for 1.5-2.5h.

10. Use of the RuO2 / Co3O4@NC bifunctional electrocatalytic material according to claim 1 or 2 in electrocatalytic hydrogen evolution and / or oxygen evolution.

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