A Co-based 2+ Anchored covalent organic framework-derived carbon-based materials, preparation methods, and applications in electrocatalysis

Abstract

A Co-based 2+ In situ anchored covalent organic framework (COFs) derived carbon-based materials, preparation methods and their applications in electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) belong to the technical field of carbon-based electrocatalytic materials. The present invention adopts a solvent thermal synthesis method to anchor Co on the covalent organic framework TRIPTA. 2+ A hollow CoO x Nanoparticle-doped bifunctional carbon-based electrocatalytic materials. This material utilizes the electronegativity difference and steric hindrance effect of the functional groups of the covalent organic framework itself to achieve the =O to Co 2+ The directional anchoring of the catalyst promotes its in-situ conversion into multivalent cobalt oxide (Co3O4 / CoO), avoiding the traditional catalytic material M‑N x The active sites are easily destroyed during application and have poor stability. It has high catalytic activity, good stability, simple preparation method and easy scalability.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon-based electrocatalytic materials, and specifically relates to a Co-based 2+ In situ anchored covalent organic frameworks (COFs)-derived carbon-based materials, their preparation methods, and their applications in electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Background Art

[0002] The energy crisis and environmental degradation have led to tremendous progress in new renewable energy applications and conversion technologies (such as metal-air batteries and fuel cells) with high energy efficiency and eco-friendliness. In these processes, the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are indispensable reactions for effectively exerting the advantages of these technologies. The sluggish kinetics of these reactions have prompted the development of efficient electrocatalysts in this field. Pt, Ir and Ru-based noble metal catalysts have been recognized to have high catalytic activity, but they have limitations such as single catalytic activity, poor stability and low reserves. Therefore, the development of high-performance non-noble metal catalysts remains an urgent problem that needs to be solved.

[0003] Transition metal-based carbon nanomaterials are considered to be the most promising non-precious metal catalysts for catalyzing ORR and OER reactions due to their rich hierarchical structures, diverse active sites and good stability. x Although the MNC (M=Fe, Co, Ni, Mo, etc.) materials with different sites have attracted the most attention, in strong alkaline electrolytes, MN x The sites may undergo electrochemical / chemical oxidation or dissolution, thereby reducing the number of active sites, resulting in such electrocatalysts being limited by their low stability in practical applications. Transition metal oxides, especially cobalt oxide (such as CoO and Co3O4), can not only provide donor / acceptor chemical adsorption sites for the reversible adsorption of oxygen in ORR and OER, but also the mixed valence state plays an important role in the electrocatalytic process. Combined with its excellent corrosion resistance, it has become an electrocatalytic material with great development potential in alkaline solutions. However, cobalt oxide has low conductivity, which limits the transfer of electrons during the reaction and thus affects its catalytic activity. To solve this problem, an effective strategy is to embed cobalt oxide into a carbon matrix to promote the electron transfer process and improve the catalytic efficiency and stability. At present, the development of carbon-based electrocatalytic materials based on cobalt oxide is still very challenging.

[0004] Covalent organic frameworks (COFs) are a new type of ordered porous material formed by covalently connecting organic units. Due to their structural, compositional, and functional controllability, as well as their high thermal stability, they are ideal precursors for the preparation of carbon-based electrocatalytic materials. Furthermore, COFs may contain elements such as O, N, and S in their skeletons, which can not only be in situ doped into the carbon matrix but also provide binding sites (such as =O groups) for different metal cations, allowing the cations to be uniformly anchored along the pores and further converted into metal oxide nanoparticles embedded in the carbon matrix, thereby achieving the controllable preparation of electrocatalytic materials. Currently, there have been no reports on the preparation of cobalt oxide-embedded carbon-based electrocatalytic materials using COFs as precursors and anchoring metal Co ions via =O groups. Summary of the Invention

[0005] The purpose of the present invention is to provide a Co-based 2+ In situ anchored covalent organic frameworks (COFs)-derived carbon-based materials, their preparation methods, and their applications in electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER).

[0006] The present invention adopts the solvothermal method to anchor Co on the covalent organic framework TRIPTA. 2+ A hollow CoO x The preparation steps of the nanoparticle-doped bifunctional carbon-based electrocatalytic material are as follows:

[0007] (1) Preparation of covalent organic framework material TRIPTA

[0008] 12.6 mg of trialdehyde phloroglucinol (Tp) and 21.3 mg of 1,3,5-tris(4-aminophenyl)triazine (DATA) were mixed, and 3 mL of 1,4-dioxane, 1 mL of mesitylene and 6 mol L -1 0.6 mL of acetic acid solution was added, ultrasonicated for 10 to 20 minutes to form a uniform mixture, and degassed by "freeze-thaw" cycle with liquid nitrogen for 3 to 5 times; the mixture was sealed and reacted in an oil bath at 110 to 130°C for 2 to 5 days, and the obtained orange-yellow product was filtered and washed with N,N-dimethylformamide, 1,4-dioxane and tetrahydrofuran in sequence, and then Soxhlet extracted with acetone, and finally dried in vacuum at 110 to 130°C to obtain the covalent organic framework material TRIPTA;

[0009] (2)Co 2+ Preparation of anchored covalent organic framework material TRIPTA-Co

[0010] Weigh 60-120 mg of cobalt nitrate hexahydrate and dissolve it in 5-10 mL of N,N-dimethylformamide, and ultrasonicate it to form a uniform solution; weigh 10 mg of TRIPTA obtained in step (1) and add it to the solution, and ultrasonicate it for 3-8 minutes to make it uniformly dispersed; the obtained suspension is sealed and subjected to solvent thermal reaction at 70-90°C for 3-6 days, and a dark yellow solid powder is obtained by filtration, which is then repeatedly washed with deionized water and anhydrous ethanol, and finally dried at 70-90°C for 10-15 hours to obtain Co 2+ Anchored covalent organic framework material TRIPTA-Co;

[0011] (3) Carbonization of covalent organic framework materials

[0012] The covalent organic framework material TRIPTA-Co obtained in step (2) is carbonized at 700-900°C for 2-4h in a nitrogen atmosphere at a heating rate of 2-10°C per minute, and then cooled to room temperature after carbonization to obtain the Co-based 2+ In situ anchored covalent organic frameworks (COFs)-derived carbon-based materials.

[0013] The present invention relates to a Co-based 2+ The ORR and OER performance tests of in situ anchored covalent organic frameworks (COFs) derived carbon-based materials were conducted using linear sweep voltammetry, cyclic sweep voltammetry, and chronoamperometric stability tests in a three-electrode system. For the ORR reaction, the electrolyte was 0.1 mol L -1 In the test, 5 mg of carbon-based electrocatalytic material was dispersed in a mixed solution containing 970 μL of anhydrous ethanol and 30 μL of naphthol, and the test solution was made after ultrasonic homogenization. It was evenly dropped on a glassy carbon rotating disk electrode with a diameter of 5 mm. After natural drying, it was electrochemically tested at different speeds (400-2025 rpm) and electrochemical timing stability tested at a fixed speed (1600 rpm). For the OER test, the reaction occurred in an O2-saturated 1 mol L -1 During the test, the test solution was evenly dripped onto a glassy carbon electrode with a diameter of 3 mm. After it was naturally dried, an electrochemical test was performed on it.

[0014] Beneficial effects of the present invention:

[0015] The present invention adopts solvent thermal synthesis method to anchor Co on the covalent organic framework material TRIPTA. 2+ A hollow CoO x Nanoparticle-doped bifunctional carbon-based electrocatalytic materials (see Figure 4 (b) Figure 7 (bd) and Figure 8 (bd)). First, as Figure 2 As shown by the UV-visible spectrum, the electronegativity difference of the functional groups of the covalent organic framework and the steric hindrance effect are used to realize the =O to Co 2+ The directional anchoring of x (Co3O4 / CoO)( Figure 3 ), avoiding the traditional catalytic material MN x The active sites are easily destroyed in applications and have poor stability. Secondly, the different valence states between the Co3O4 / CoO phase interfaces in the obtained carbon-based electrocatalytic materials can be quickly converted, and their special spherical hollow structures and layered carbon nanowires ( Figure 4 (c, d)) structures all promote the rapid occurrence of the catalytic reaction; Finally, the Co 2+ The anchored covalent organic framework method is simple to operate, easy to scale up, and can be extended to other transition metal ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 : X-ray diffraction patterns of synthesized TRIPTA and TRIPTA-Co;

[0017] Figure 2 : Solid-state UV absorption spectra of TRIPTA, TRIPTA-Co, cobalt nitrate hexahydrate, cobalt-o-phenanthroline complex and o-phenanthroline;

[0018] Figure 3 :NC-800、CoO x @NC-700-1:10、CoO x @NC-800-1:10、CoO x X-ray diffraction pattern of @NC-900-1:10;

[0019] Figure 4 :Synthesized CoO x Scanning electron microscopy (SEM) images (a) and transmission electron microscopy (TEM) images (b-d) of @NC-800-1:10;

[0020] Figure 5 :Synthesized CoO x @NC-800-1:10 high-angle annular dark field image (a), elemental energy spectrum (b), and corresponding C (c), N (d), O (e), and Co (f) element mapping;

[0021] Figure 6: Scanning electron microscopy (SEM) (a) and transmission electron microscopy (TEM) (b-d) images of synthesized NC-800-1:10;

[0022] Figure 7 :Synthesized CoO x Scanning electron microscopy (SEM) images (a) and transmission electron microscopy (TEM) images (b-d) of @NC-700-1:10;

[0023] Figure 8 :Synthesized CoO x Scanning electron microscopy (SEM) images (a) and transmission electron microscopy (TEM) images (b-d) of @NC-900-1:10;

[0024] Figure 9 :Synthesized TRIPTA, TRIPTA-Co, NC-800, CoO x @NC-700-1:10、CoO x @NC-800-1:10、CoO x Nitrogen adsorption-desorption curve (a) and pore size distribution diagram (b) of @NC-900-1:10;

[0025] Figure 10 :Synthesized NC-800, CoO x @NC-700-1:10、CoO x @NC-800-1:10、CoO x LSV curves of ORR of @NC-900-1:10 and commercial 20% Pt / C (a), CoO x @NC-800-1:10 LSV curve and KL diagram (b) and CoO at different speeds x @NC-800-1:10 and commercial 20% Pt / C chronometry stability curves (c);

[0026] Figure 11 :Synthesized CoO x @NC-800-1:10 HTMA poisoning test curve of carbon-based materials;

[0027] Figure 12 :Synthesized NC-800, CoO x @NC-700-1:10、CoO x @NC-800-1:10、CoO x @NC-900-1:10 OER kinetic curves of carbon-based materials (a) and CoO x @NC-800-1:10 stability test curve (b).

[0028] Figure 1 The X-ray diffraction patterns of TRIPTA and TRIPTA-Co synthesized in Example 1 show that TRIPTA and TRIPTA-Co have characteristic peaks at 5.6°, 9.7° and 26.7°, which are typical peaks of covalent organic frameworks. After the solvothermal reaction, the peak positions of XRD did not change significantly, indicating that Co 2+ The introduction of has no effect on the morphological structure of TRIPTA itself;

[0029] Figure 2 Solid UV absorption spectra of TRIPTA, TRIPTA-Co, cobalt nitrate hexahydrate, cobalt-phenanthroline complex and phenanthroline (phenanthroline is introduced to contrast with the peak of cobalt-phenanthroline complex, proving that the peaks at 228 and 267 nm are from phenanthroline ligand rather than the characteristic peaks of the complex) synthesized in Example 1. Compared with TRIPTA, TRIPTA-Co has a broad peak at 687 nm, proving that Co 2+ Compared with the cobalt-o-phenanthroline complex with Co-N coordination, TRIPTA-Co does not have the corresponding characteristic peak, which proves that Co 2+ No coordination occurs with N-containing groups.

[0030] Figure 3 NC-800, CoO synthesized in Example 1, Example 5, Example 6, and Comparative Example 1 x @NC-700-1:10、CoO x @NC-800-1:10、CoO x The X-ray diffraction pattern of @NC-900-1:10, comparing the X-ray diffraction spectrum of the synthesized carbon material with the standard spectrum, shows a characteristic peak at 26.3°, which matches graphite carbon (JCPDS 75-1621). The remaining peaks can also correspond to crystalline Co3O4 (JCPDS 42-1467) and CoO (JCPDS 71-1178).

[0031] Figure 4 CoO synthesized in Example 1 xScanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of @NC-800-1:10. As can be seen from Figure (a), the synthesized material has a distinct nanowire structure composed of stacked sheets. This is due to the π-π stacking of monomer sheets within the covalent organic framework itself. Under strong external forces such as ultrasound, it collapses into nanosheets as shown in Figure (b). TEM images in Figures (c) and (d) show that the lattice spacings of 0.283 nm and 0.244 nm in the structure correspond to the (220) and (311) crystal planes of Co3O4, respectively, and the lattice spacing of 0.211 nm coincides with the (200) crystal plane of CoO. The two coexist in the same hollow nanoparticle and form a phase interface. This rapid conversion of different cobalt oxidation states at the interface is beneficial to improving the activity of the catalytic material.

[0032] Figure 5 CoO synthesized in Example 1 x Elemental energy spectrum of @NC-800-1:10. As can be seen from the figure, there are four elements: carbon, nitrogen, oxygen, and cobalt. Each element is evenly distributed in the material's structure, proving the efficiency of this synthesis method.

[0033] Figure 6 Scanning electron micrographs (SEM) and transmission electron micrographs (TEM) of NC-800 synthesized in Comparative Example 1 show that NC-800 exhibits a nanowire morphology composed of stacked sheets, consistent with the inherent properties of TRIPTA. Figures (c) and (d) reveal that the lattice spacing of NC-800 is 0.338 nm, consistent with the (002) crystal plane of graphitic carbon.

[0034] Figure 7 CoO synthesized in Example 5 x @NC-700-1:10 scanning (SEM) and transmission (TEM) electron microscopy images, as shown in Figures (a) and (b), CoO x @NC-700 retains the original morphological features of the covalent organic framework material TRIPTA, which is a nanowire structure formed by the accumulation of carbon nanosheets. The crystal planes corresponding to graphite carbon and the crystal planes of Co3O4 and CoO are also found in Figure (c) and Figure (d). However, unlike CoO x @NC-800-1:10, both oxides exist as separate hollow particles.

[0035] Figure 8 CoO synthesized in Example 6 x @NC-900-1:10 scanning (SEM) and transmission (TEM) electron microscopy images, as shown in Figures (a) and (b), CoO x@NC-900-1:10 also inherits the morphological characteristics of the covalent organic framework material TRIPTA, with a nanowire structure composed of stacked carbon nanosheets. Figures (c) and (d) also reveal crystal planes corresponding to graphitic carbon and Co3O4 and CoO, respectively, but they still tend to exist as two separate hollow particles.

[0036] Figure 9 TRIPTA, TRIPTA-Co, NC-800, CoO synthesized in Example 1, Example 5, Example 6, and Comparative Example 1 x @NC-700-1:10、CoO x @NC-800-1:10、CoO x Nitrogen adsorption-desorption curve and pore size distribution of @NC-900-1:10. The IV type isotherm in Figure (a) shows that the obtained material has coexistence of micropores and mesopores. 2+ After anchoring, the specific surface area of TRIPTA decreases. 2+ In the case of Co, NC-800 has the lowest specific surface area, indicating that its skeleton collapsed during the carbonization process. 2+ When anchored, the skeleton of the carbon-based catalytic material is stabilized and the specific surface area is high. As shown in Figure (b), with the increase of carbonization temperature, the 0.6nm micropores in the carbon structure disappear and the mesopores (2.5-4.0nm) gradually form, which is beneficial to the exposure of active sites and the acceleration of mass transfer during the electrocatalytic process. The highest specific surface area and the appropriate amount of mesopores together contribute to the high specific surface area of CoO x @NC-800-1:10 has the highest performance.

[0037] Figure 10 NC-800, CoO synthesized in Example 1, Example 5, Example 6, and Comparative Example 1 x @NC-700-1:10、CoO x @NC-800-1:10、CoO x ORR kinetics and CoO of @NC-900-1:10 x @NC-800 stability test diagram, and compared with commercial 20wt% Pt / C. As can be seen from Figure (a), the synthesized CoO x @NC-800-1:10 carbon-based material has the best performance, with a half-wave potential of 0.89V, which is higher than the half-wave potential of 0.84V of commercial 20wt% Pt / C. Figure (b) shows that the reaction is a typical four-electron transfer reaction with high mass transfer efficiency. From the constant voltage timing stability test in Figure (c), it can be seen that the synthesized CoO x@NC-800-1:10 can still maintain 99.79% of its original performance under 10-hour long-term working conditions, with excellent stability.

[0038] Figure 11 For the synthesized CoO x @NC-800 carbon-based material HTMA poisoning test diagram, due to the Co in aqueous solution 2+ It has a strong binding ability with hexamethylenetetramine, so it can be used to detect Co-N in materials. x The presence of active sites. As can be seen from the figure, when the concentration of hexamethylenetetramine in the electrolyte increases from 10mmol / L to 30mmol / L, CoO x The limiting current density and half-wave potential of @NC-800 did not change significantly, confirming that the Co-N x The active site does not exist, which in turn confirms that Co 2+ It is anchored at the oxygen site of the TRIPTA skeleton.

[0039] Figure 12 NC-800, CoO synthesized in Example 1, Example 5, Example 6, and Comparative Example 1 x @NC-700-1:10、CoO x @NC-800-1:10、CoO x @NC-900-1:10 OER kinetics of carbon-based materials and CoO x @NC-800-1:10 stability test diagram, and compared with commercial RuO2. As can be seen from Figure (a), the synthesized CoO x @NC-800-1:10 carbon-based material has the best performance, with an overpotential of 0.36V, slightly lower than commercial RuO2 (0.31V); as can be seen from the cyclic voltammetry test in Figure (b), after 3000 cycles of CV, CoO x @NC-800-1:10 has a performance drop of only 12.3mV, and excellent stability. DETAILED DESCRIPTION

[0040] In the following, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Prior to the description, it should be understood that the terms used in the specification and the appended claims are not to be construed as limited to their general and dictionary meanings, but rather should be interpreted based on the meanings and concepts corresponding to the technical aspects of the present invention, based on the principle of allowing the inventor to appropriately define the terms for the best interpretation. Therefore, the description herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of the present invention. It should be understood that other equivalent implementations and modifications may be made without departing from the spirit and scope of the present invention.

[0041] Example 1:

[0042] (1) Preparation of covalent organic framework material TRIPTA

[0043] After adding 12.6 mg of Tp and 21.3 mg of DATA to a 25 mL dry solvent storage bottle, add 3 mL of 1,4-dioxane, 1 mL of mesitylene, and 0.6 mL of 6 mol / L acetic acid solution. Ultrasonicate for 10 min to form a homogeneous mixture. Degas the mixture three times using a "freeze-thaw" cycle using liquid nitrogen and a high vacuum pump (the entire process is achieved using a double-row tube. After ultrasonication, place the solvent storage bottle in liquid nitrogen and freeze it to liquid nitrogen temperature until there is no liquid in the bottle. Open the double-row tube valve and evacuate for 30 minutes; close the valve, remove the solvent storage bottle, thaw it to room temperature, and open the double-row tube valve again to evacuate. Repeat the above steps three times). Seal the storage bottle and react in an oil bath at 120°C for 3 days. The obtained orange-yellow product was filtered and washed with N,N-dimethylformamide, 1,4-dioxane and a large amount of tetrahydrofuran, then Soxhlet extracted with acetone, and finally dried thoroughly in a vacuum drying oven at 120°C to obtain about 23.3 mg of the covalent organic framework material TRIPTA.

[0044] (2)Co 2+ Preparation of anchored covalent organic framework material TRIPTA-Co-1:10

[0045] Weigh 100 mg of cobalt nitrate hexahydrate and dissolve it in 5 mL of N,N-dimethylformamide, and ultrasonicate it to form a uniform solution. Weigh 10 mg of TRIPTA prepared in step (1) and add it to the solution, and ultrasonicate it for 5 minutes to make it uniformly dispersed. The obtained suspension was sealed in a glass bottle and placed in an 80°C oven for solvent thermal reaction for 5 days. The dark yellow solid powder obtained by filtration was repeatedly washed with deionized water and anhydrous ethanol, and finally placed in an 80°C oven to dry for 12 hours to obtain Co 2+ The anchored covalent organic framework material TRIPTA-Co is about 11.4 mg, recorded as TRIPTA-Co-1:10 (1:10 refers to the mass ratio of TRIPTA to cobalt nitrate hexahydrate).

[0046] (3)Co 2+ Carbonization of anchored covalent organic frameworks

[0047] The covalent organic framework material TRIPTA-Co-1:10 obtained in the above step (2) was placed in a 10 mL porcelain boat, covered with a porcelain boat lid, and placed in a tube furnace. Carbonized at 800 ° C for 3 h in a nitrogen atmosphere with a heating rate of 5 ° C per minute. After the temperature in the tube furnace returned to room temperature, the porcelain boat was taken out to obtain the carbonized CoO xDoped carbon-based electrocatalytic material (yield of about 55%), namely the Co-based 2+ In situ anchored covalent organic frameworks (COFs) derived carbon-based materials, denoted as CoO x @NC-800-1:10;

[0048] (4) To obtain CoO x Doped carbon-based electrocatalytic material CoO x @NC-800-1:10 performs powder XRD diffraction pattern measurement, SEM and TEM scanning and electrochemical performance testing

[0049] ORR test: Linear sweep voltammetry was used for kinetic testing at 400-2025 rpm, and chronoamperometric stability was tested at a fixed 1600 rpm for 10 h.

[0050] OER test: Linear sweep voltammetry was used for kinetic testing, and 3000 cycles of cyclic sweep voltammetry were performed in the voltage range of 1.0 to 1.8 V (vs. RHE).

[0051] The test results showed that in the ORR test, Figure 10 As shown in (b), with the increase of the rotation speed, the obtained CoO x The limiting current density of the @NC-800-1:10 carbon-based electrocatalytic material gradually increases. At a rotation speed of 1600 rpm, its starting potential is 1.02 V, half-wave potential is 0.89 V, and limiting current density is 5.18 mA / cm 2 ; Fixed speed 1600rpm and voltage 0.5V, monitor the current change over time within 10h, such as Figure 10 As shown in (c), the corresponding current only decreases by 0.21% over time, indicating that this material has excellent ORR kinetic catalytic performance and long-term working stability under alkaline conditions. Figure 12 As shown in (a), the obtained CoO x @NC-800-1:10 Carbon-based electrocatalytic material at 10mA / cm 2 The overpotential E 10 The linear scan curve after 3000 cycles of cyclic sweep voltammetry test is shown in Figure 2. Figure 12 (b) Compared with the initial value, there is only a negative shift of 12.3 mV, indicating that this material has excellent OER catalytic performance and long-term stability under alkaline conditions.

[0052] Comparative Example 1:

[0053] (1) Prepare the covalent organic framework material TRIPTA according to step 1 of Example 1;

[0054] (2) carbonizing the covalent organic framework material TRIPTA according to step (3) of Example 1 to obtain a nitrogen-doped carbon-based electrocatalytic material, which is designated as NC-800;

[0055] (3) The obtained nitrogen-doped carbon-based electrocatalytic material NC-800 was subjected to powder XRD diffraction pattern measurement, SEM and TEM scanning, and electrochemical performance testing;

[0056] The test results show that in the ORR test, the NC-800 carbon-based electrocatalytic material has an onset potential of 0.89 V, a half-wave potential of 0.72 V, and a limiting current density of 4.37 mA / cm 2 In the OER test, the obtained NC-800 carbon-based electrocatalytic material did not reach 10mA / cm 2 evaluation criteria, indicating that its overall electrocatalytic performance is poor.

[0057] Example 2:

[0058] (1) Prepare the covalent organic framework material TRIPTA according to step (1) of Example 1;

[0059] (2) A covalent organic framework material TRIPTA-Co was prepared according to step (2) of Example 1, wherein the amount of cobalt nitrate hexahydrate added was 60 mg. The obtained covalent organic framework material was recorded as TRIPTA-Co-1:6;

[0060] (3) The covalent organic framework material TRIPTA-Co-1:6 was carbonized according to step (3) of Example 1 at a carbonization temperature of 800°C. The carbon-based electrocatalytic material obtained after carbonization was recorded as CoO x @NC-800-1:6;

[0061] (4) Obtaining carbon-based electrocatalytic material CoO x @NC-800-1:6 for electrochemical ORR catalytic performance testing;

[0062] The test results show that the obtained CoO x @NC-800-1:6 The carbon-based electrocatalytic material has an onset potential of 0.94 V, a half-wave potential of 0.81 V, and a limiting current density of 4.78 mA / cm 2 , its overall electrocatalytic performance is slightly lower than that of Example 1.

[0063] Example 3:

[0064] (1) Prepare the covalent organic framework material TRIPTA according to step (1) of Example 1;

[0065] (2) A covalent organic framework material TRIPTA-Co was prepared according to step (2) of Example 1, wherein the amount of cobalt nitrate hexahydrate added was 80 mg. The resulting covalent organic framework material was designated TRIPTA-Co-1:8.

[0066] (3) The covalent organic framework material TRIPTA-Co-1:8 was carbonized according to step (3) of Example 1 at a carbonization temperature of 800°C. The carbon-based electrocatalytic material obtained after carbonization was recorded as CoO x @NC-800-1:8;

[0067] (4) Obtaining carbon-based electrocatalytic material CoO x @NC-800-1:8 for electrochemical ORR catalytic performance testing;

[0068] The test results show that the obtained CoO x @NC-800-1:8 The carbon-based electrocatalytic material has an onset potential of 1.00 V, a half-wave potential of 0.86 V, and a limiting current density of 4.53 mA / cm 2 , its overall electrocatalytic performance is slightly lower than that of Example 1.

[0069] Example 4:

[0070] (1) Prepare the covalent organic framework material TRIPTA according to step (1) of Example 1;

[0071] (2) A covalent organic framework material TRIPTA-Co was prepared according to step (2) of Example 1, wherein the amount of cobalt nitrate hexahydrate added was 120 mg. The resulting covalent organic framework material was designated TRIPTA-Co-1:12.

[0072] (3) The covalent organic framework material TRIPTA-Co-1:12 was carbonized according to step (3) of Example 1 at a carbonization temperature of 800°C. The carbon-based electrocatalytic material obtained after carbonization was recorded as CoO x @NC-800-1:12;

[0073] (4) Obtaining carbon-based electrocatalytic material CoO x @NC-800-1:12 Conduct electrochemical ORR catalytic performance test;

[0074] The test results show that the obtained CoO x @NC-800-1:12 The carbon-based electrocatalytic material has an onset potential of 1.00 V, a half-wave potential of 0.88 V, and a limiting current density of 4.76 mA / cm 2 , its overall electrocatalytic performance is slightly lower than that of Example 1.

[0075] Example 5:

[0076] (1) Prepare the covalent organic framework material TRIPTA according to step (1) of Example 1;

[0077] (2) Prepare the covalent organic framework material TRIPTA-Co according to step (2) of Example 1;

[0078] (3) Carbonizing the covalent organic framework material TRIPTA-Co according to step (3) of Example 1 at a carbonization temperature of 700° C. to obtain CoO x Doped carbon-based electrocatalytic material, denoted as CoO x @NC-700-1:10;

[0079] (4) The obtained CoO x Carbon-based electrocatalytic material CoO x @NC-700-1:10 performs powder XRD diffraction pattern measurement, SEM and TEM scanning and electrochemical performance testing;

[0080] The test results show that in the ORR test, the obtained CoO x @NC-700-1:10 The carbon-based electrocatalytic material has an onset potential of 0.89 V, a half-wave potential of 0.87 V, and a limiting current density of 4.14 mA / cm 2 ; In the OER test, the obtained CoO x @NC-700-1:10 Carbon-based electrocatalytic material at 10mA / cm 2 The overpotential E 10 The overall electrocatalytic performance is slightly lower than that of Example 1.

[0081] Example 6:

[0082] (1) Prepare the covalent organic framework material TRIPTA according to step (1) of Example 1;

[0083] (2) Prepare the covalent organic framework material TRIPTA-Co according to step (2) of Example 1;

[0084] (3) Carbonizing the covalent organic framework material according to step (3) of Example 1 at a carbonization temperature of 900° C. to obtain CoO x Doped carbon-based electrocatalytic material, denoted as CoO x @NC-900-1:10;

[0085] (4) To obtain CoO x Carbon-based electrocatalytic material CoO x @NC-900-1:10 performs powder XRD diffraction pattern measurement, SEM and TEM scanning and electrochemical performance testing;

[0086] The test results show that in the ORR test, the obtained CoO x @NC-900-1:10 carbon-based electrocatalytic material has an onset potential of 1.00 V, a half-wave potential of 0.89 V, and a limiting current density of 4.37 mA / cm 2 ; In the OER test, the obtained CoO x @NC-900-1:10 Carbon-based electrocatalytic material at 10mA / cm 2 The overpotential E 10 The overall electrocatalytic performance is slightly lower than that of Example 1.

[0087] By comparing the performance of the cobalt-doped carbon-based electrocatalytic materials synthesized in Examples 1-6 and Comparative Example 1, we can find that with the changes in the carbonization temperature and the amount of cobalt nitrate hexahydrate added, the starting potential, half-wave potential and limiting current density of the linear sweep voltammetry curve all change, and the more the amount added, the higher the carbonization temperature is not necessarily the case, and the better the electrochemical performance is. There is a maximum point in the adjustment corresponding to the amount of addition, temperature and performance, at which time the electrochemical performance reaches the optimal state.

Claims

1. A Co-based 2+ The preparation method of the in-situ anchored covalent organic framework-derived carbon-based material comprises the following steps: (1)Co 2+ Preparation of anchored covalent organic framework material TRIPTA-Co Weigh 60-120 mg of cobalt nitrate hexahydrate and dissolve it in 5-10 mL of N,N-dimethylformamide, and ultrasonicate it to form a uniform solution; weigh 10 mg of covalent organic framework material TRIPTA and add it to the solution, and ultrasonicate it to make it uniformly dispersed; the obtained suspension is sealed and subjected to solvent thermal reaction at 70-90 ° C for 3-6 days, and a dark yellow solid powder is obtained by filtration, which is then repeatedly washed with deionized water and anhydrous ethanol, and finally dried at 70-90 ° C for 10-15 h to obtain Co 2+ Anchored covalent organic framework material TRIPTA-Co; (2) Carbonization of covalent organic framework materials The covalent organic framework material TRIPTA-Co obtained in step (1) is carbonized in a nitrogen atmosphere at 700-900°C for 2-4h, and then cooled to room temperature to obtain Co-based 2+ In situ anchored covalent organic framework-derived carbon-based materials.

2. A Co-based 2+ A method for preparing an in-situ anchored covalent organic framework-derived carbon-based material, characterized by: 12.6 mg of trialdehyde phloroglucinol and 21.3 mg of 1,3,5-tris(4-aminophenyl)triazine were mixed, and then 3 mL of 1,4-dioxane, 1 mL of mesitylene and 6 mol L -1 The mixture was added with 0.6 mL of acetic acid solution and ultrasonicated for 10 to 20 minutes to form a uniform mixture. The mixture was degassed by freeze-thaw cycles for 3 to 5 times with liquid nitrogen. The mixture was sealed and reacted in an oil bath at 110 to 130°C for 2 to 5 days. The obtained orange-yellow product was filtered and washed with N,N-dimethylformamide, 1,4-dioxane and tetrahydrofuran in sequence, and then Soxhlet extracted with acetone. Finally, the mixture was dried in vacuo at 110 to 130°C to obtain the covalent organic framework material TRIPTA.

3. A Co-based 2+ A method for preparing an in-situ anchored covalent organic framework-derived carbon-based material, characterized by: The heating rate during carbonization in step (2) is 2 to 10° C. per minute.

4. A Co-based 2+ In situ anchored covalent organic framework-derived carbon-based materials, characterized by: It is prepared by the method described in claim 1, 2, or 3.

5. A Co-based 2+ Application of in situ anchored covalent organic framework-derived carbon-based materials in electrocatalytic oxygen reduction reaction or oxygen evolution reaction.

Images