A cobalt nanoparticle-loaded yeast carbon-based electrocatalyst and preparation and application thereof

Abstract

The present application relates to a kind of yeast carbon-based electrocatalyst of cobalt nanoparticles and its preparation and application, belong to electrocatalyst technical field.The specific preparation steps are: first, yeast is pre-carbonized in air, then fully mixed with inorganic salt and calcined in inert gas atmosphere at high temperature, then washed with acidic reagent until the filtrate is neutral and dried to obtain yeast carbon-based, then the yeast carbon-based is dispersed into organic solution and added into the solution containing cobalt salt and nitrogen-containing chelating agent, after filtration and drying, calcined at high temperature in nitrogen atmosphere, to obtain the yeast carbon-based material of cobalt nanoparticles.The yeast carbon-based material of cobalt nanoparticles shows excellent oxygen reduction catalytic performance.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalyst technology, and more specifically, relates to a yeast-based carbon electrocatalyst supported on cobalt nanoparticles, its preparation and application. Background Technology

[0002] Metal-air batteries and fuel cells hold promise as next-generation commercially viable new energy batteries due to their clean and environmentally friendly advantages. However, the slow-kinetic oxygen reduction reaction occurring at the cathode hinders their large-scale application. While platinum-based catalysts can address the slow kinetics issue to some extent, their high cost, low availability, and poor stability limit their commercial application. Therefore, exploring inexpensive, readily available, highly efficient, stable, and simple-to-prepare non-precious metal catalysts is crucial for promoting the large-scale use of metal-air batteries and fuel cells.

[0003] Yeast has advantages such as low cost, environmental friendliness, and rich doping elements, and has broad application prospects in the preparation of low-cost, highly active electrocatalysts. Summary of the Invention

[0004] This invention provides a yeast-based carbon electrocatalyst supported on cobalt nanoparticles and its preparation method. The aim is to use inexpensive and readily available yeast to prepare a low-cost, efficient, and stable electrocatalyst through simple activation, adsorption, and other methods.

[0005] According to a first aspect of the present invention, a method for preparing a yeast-based carbon electrocatalyst supported on cobalt nanoparticles is provided, comprising the following steps:

[0006] (1) Yeast carbon is obtained by carbonization of yeast, then mixed thoroughly with inorganic salt, and then calcined. The inorganic salt is calcined into a molten state, and the yeast carbon is etched into a porous carbon structure by the molten inorganic salt.

[0007] (2) The material obtained in step (1) is first acid-washed, then washed with deionized water, then dried and dispersed in an organic solvent;

[0008] (3) Disperse the cobalt salt and nitrogen-containing chelating agent in an organic solvent, whereby the cobalt salt and nitrogen-containing chelating agent form a cobalt complex; then add the dispersion obtained in step (2) to incorporate the cobalt complex into the porous structure of yeast carbon. After centrifugation, take the precipitate and dry it to obtain the precursor material.

[0009] (4) The precursor material obtained in step (3) is calcined in a non-oxidizing protective atmosphere to pyrolyze the cobalt complex to obtain cobalt nanoparticles, that is, yeast carbon-based electrocatalyst loaded with cobalt nanoparticles.

[0010] Preferably, in step (3), the nitrogen-containing chelating agent is o-phenanthroline, 2,2-bipyridine, or ethylenediamine.

[0011] Preferably, the molar ratio of the cobalt salt to the nitrogen-containing chelating agent is 1:(1-4).

[0012] Preferably, in step (1), the inorganic salt is sodium carbonate, potassium carbonate, sodium chloride, or potassium chloride.

[0013] Preferably, in step (1), the yeast is heated at a temperature of 200-500°C for 1-3 hours to carbonize the yeast.

[0014] Preferably, in step (1), the calcination temperature is 600-900°C and the calcination time is 1-3 hours.

[0015] Preferably, in step (4), the calcination temperature is 700-900°C and the time is 2-4 hours.

[0016] According to another aspect of the present invention, a yeast carbon-based electrocatalyst loaded with cobalt nanoparticles prepared by any of the methods described in any one of the present invention is provided.

[0017] Preferably, in the yeast carbon-based electrocatalyst loaded with cobalt nanoparticles, the particle size of the cobalt nanoparticles is 10–20 nm.

[0018] According to another aspect of the invention, the application of the yeast-based carbon electrocatalyst supported on cobalt nanoparticles is provided for use as an oxygen reduction catalyst.

[0019] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages:

[0020] (1) This invention utilizes inorganic salts that are in a molten state under high temperature conditions to conveniently and quickly etch out yeast carbon-based materials with rich porous structure and large specific surface area.

[0021] (2) The yeast carbon-based and nitrogen-containing chelating agent of the present invention provides abundant doped nitrogen elements, which can effectively improve catalytic performance.

[0022] (3) The cobalt nanoparticles loaded in this invention have a strong interaction with nitrogen and carbon atoms, which can achieve the purpose of adjusting the electronic structure of the doped carbon, thereby increasing the adsorption energy of the catalyst for oxygen.

[0023] (4) The present invention uses inexpensive and readily available yeast and non-precious metal cobalt to prepare an oxygen reduction catalyst with excellent performance through simple steps. Attached Figure Description

[0024] Figure 1This is a scanning electron microscope (SEM) image of the carbon-based structure of the treated yeast.

[0025] Figure 2 Transmission electron microscopy (TEM) image of the yeast carbon-based electrocatalyst loaded with cobalt nanoparticles prepared in Example 1.

[0026] Figure 3 The image shows the X-ray diffraction (XRD) pattern of the yeast carbon-based electrocatalyst loaded with cobalt nanoparticles prepared in Example 1. The vertical axis represents the peak intensity, and the horizontal axis represents twice the diffraction angle.

[0027] Figure 4 Transmission electron microscopy (TEM) image of the yeast carbon-based electrocatalyst loaded with cobalt nanoparticles prepared in Example 2.

[0028] Figure 5 This is a linear sweep voltammetry (LSV) curve of the yeast carbon-based electrocatalyst loaded with cobalt nanoparticles prepared in Example 1 in a KOH electrolyte saturated with oxygen. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0030] The yeast carbon-based electrocatalyst supported on cobalt nanoparticles in this invention is a yeast carbon-based electrocatalyst supported on cobalt nanoparticles. The yeast carbon-based electrocatalyst is obtained by pre-carbonization and activation treatment of yeast. The cobalt nanoparticles are obtained by pyrolysis of coordination compounds of metallic cobalt at high temperature. The size of the cobalt nanoparticles is nanoscale, with a particle size of 10-20 nm.

[0031] The specific steps of the preparation method of the yeast carbon-based electrocatalyst supported on cobalt nanoparticles in this invention are as follows:

[0032] 1) Pre-carbonize the washed and dried yeast in air at a temperature of 200-500℃ for 1-3 hours;

[0033] 2) Thoroughly mix the material obtained in step 1) with inorganic salt; activate the resulting mixture at 600-900°C in an inert gas atmosphere for 1-3 hours;

[0034] Wherein, the mass ratio of the material obtained in step 1) to the inorganic salt is 1:1 to 1:5;

[0035] 3) Add an acidic reagent to the material obtained in step 2) and stir for 1 to 2 hours; wash the material with deionized water until the filtrate is neutral (pH=7), and then dry the material at 40 to 80°C for 12 to 24 hours to obtain yeast carbon-based products;

[0036] The concentration of the acidic reagent is 1–5 mol / L;

[0037] 4) Add the yeast carbon-based solution obtained in step 3) to 50-100 ml of isopropanol solution and sonicate to obtain a uniformly dispersed yeast carbon-based dispersion.

[0038] 5) Add the cobalt salt and nitrogen-containing chelating agent to 50-100 ml of ethanol solution and stir continuously to obtain a dispersion solution of the coordination compound formed by the cobalt salt and nitrogen-containing chelate;

[0039] The molar mass ratio of the cobalt salt to the nitrogen-containing chelating agent is 1:1 to 1:4.

[0040] 6) Add the yeast carbon-based dispersion obtained in step 4) to the solution in step 5), stir at 20-50°C for 10-24 hours, centrifuge, and then dry the material at 40-80°C for 12-24 hours to obtain the precursor material.

[0041] 7) The precursor material obtained in step 6) is calcined at 700-900°C in a nitrogen atmosphere for 2-4 hours to obtain a yeast carbon-based electrocatalyst loaded with cobalt nanoparticles.

[0042] The yeast in this invention can be any species of yeast in the class Yeastae.

[0043] The inorganic salt in this invention is any one of sodium carbonate, potassium carbonate, sodium chloride, and potassium chloride.

[0044] The acidic reagent used in this invention is any one of hydrochloric acid, sulfuric acid, and nitric acid.

[0045] The nitrogen-containing chelating agent in this invention is any one of o-phenanthroline, 2,2-bipyridine, and ethylenediamine.

[0046] The inert gas used in this invention is any one of helium, neon, argon, krypton, and xenon.

[0047] The yeast-based carbon electrocatalyst supported on cobalt nanoparticles obtained in this invention exhibits excellent oxygen reduction catalytic activity.

[0048] Example 1

[0049] Pre-carbonize 50g of washed and dried yeast in air at 300℃ for 2 hours.

[0050] Weigh 200 mg of pre-carbonized yeast and 400 mg of potassium carbonate and mix them evenly. Activate the mixture at 800 °C in an argon atmosphere for 1 hour.

[0051] A prepared 1 mol / L hydrochloric acid solution was added to the activated yeast, and the mixture was stirred for 2 hours and filtered. The material was washed with deionized water until the filtrate was neutral (pH = 7). The material was then dried at 60°C for 24 hours to obtain yeast carbon-based products. The prepared yeast carbon-based products exhibited a loose and porous morphology, such as... Figure 1 As shown.

[0052] Weigh 30 mg of yeast carbon-based material and add it to 60 ml of isopropanol solution and sonicate to obtain a uniformly dispersed yeast carbon-based dispersion.

[0053] 0.3 mmol of cobalt nitrate and 0.6 mmol of o-phenanthroline were added to 50 ml of ethanol solution and stirred continuously to obtain a dispersion of the coordination compound formed by cobalt nitrate and o-phenanthroline.

[0054] The yeast carbon-based dispersion was added to the above solution, stirred at 30°C for 12 hours, and then centrifuged. The separated material was then dried at 60°C for 12 hours to obtain the precursor material.

[0055] Yeast-based carbon electrocatalysts loaded with cobalt nanoparticles were prepared by calcining the precursor material at 700℃ in a nitrogen atmosphere for 2 hours.

[0056] The prepared yeast-based carbon electrocatalyst loaded with cobalt nanoparticles was observed using transmission electron microscopy (TEM). TEM results showed that the cobalt nanoparticles were uniformly dispersed within the yeast carbon matrix. Figure 2 As shown.

[0057] Figure 3 The XRD pattern of the yeast carbon-based electrocatalyst loaded with cobalt nanoparticles prepared in this example shows that there are obvious characteristic peaks of elemental cobalt in the sample.

[0058] Figure 5 The linear sweep voltammetry (LSV) curve of the yeast carbon-based electrocatalyst loaded with cobalt nanoparticles prepared in this embodiment was obtained by testing in a KOH electrolyte saturated with oxygen. The curve shows the half-wave potential (E) of the electrocatalyst. 1 / 2 The voltage was 0.854 V (relative to the reversible hydrogen electrode), which proves that the electrocatalyst has good oxygen reduction catalytic performance.

[0059] Example 2

[0060] Pre-carbonize 50g of washed and dried yeast in air at 400℃ for 2 hours.

[0061] Weigh 200 mg of pre-carbonized yeast and 400 mg of potassium carbonate and mix them evenly. Activate the resulting mixture at 700 °C in an argon atmosphere for 2 hours.

[0062] Add a prepared 2 mol / L hydrochloric acid solution to the activated yeast, stir for 1 hour and filter. Wash the material with deionized water until the filtrate is neutral (pH=7). Then dry the material at 50°C for 15 hours to obtain yeast carbon-based yeast.

[0063] Weigh 50 mg of yeast carbon-based material and add it to 80 ml of isopropanol solution and sonicate to obtain a uniformly dispersed yeast carbon-based dispersion.

[0064] 0.5 mmol of cobalt nitrate and 0.5 mmol of o-phenanthroline were added to 90 ml of ethanol solution and stirred continuously to obtain a dispersion of the coordination compound formed by cobalt nitrate and o-phenanthroline.

[0065] The yeast carbon-based dispersion was added to the above solution, stirred at 40°C for 12 hours, and then centrifuged. The separated material was then dried at 60°C for 12 hours to obtain the precursor material.

[0066] Yeast-based carbon electrocatalysts loaded with cobalt nanoparticles were prepared by calcining the precursor material at 800℃ in a nitrogen atmosphere for 2 hours.

[0067] The prepared yeast-based carbon electrocatalyst loaded with cobalt nanoparticles was observed using transmission electron microscopy (TEM). TEM revealed that the cobalt nanoparticles were uniformly dispersed within the yeast carbon matrix, but the particle size had increased. Figure 4 As shown.

[0068] Example 3

[0069] Pre-carbonize 50g of washed and dried yeast in air at 500℃ for 2 hours.

[0070] Weigh 200 mg of pre-carbonized yeast and 800 mg of sodium chloride and mix them evenly. Activate the mixture at 900 °C in an argon atmosphere for 1 hour.

[0071] Add a prepared 2 mol / L sulfuric acid solution to the activated yeast, stir for 1 hour and filter. Wash the material with deionized water until the filtrate is neutral (pH=7). Then dry the material at 60°C for 20 hours to obtain yeast carbon-based yeast.

[0072] Weigh 40 mg of yeast carbon-based material and add it to 70 ml of isopropanol solution and sonicate to obtain a uniformly dispersed yeast carbon-based dispersion.

[0073] 0.4 mmol of cobalt sulfate and 1.2 mmol of o-phenanthroline were added to 80 ml of ethanol solution and stirred continuously to obtain a dispersion of the coordination compound formed by cobalt sulfate and o-phenanthroline.

[0074] The yeast carbon-based dispersion was added to the above solution, stirred at 30°C for 24 hours, and then centrifuged. The separated material was then dried at 50°C for 12 hours to obtain the precursor material.

[0075] Yeast-based carbon electrocatalysts loaded with cobalt nanoparticles were prepared by calcining the precursor material at 700℃ in a nitrogen atmosphere for 3 hours.

[0076] Example 4

[0077] Pre-carbonize 50g of washed and dried yeast in air at 400℃ for 3 hours.

[0078] Weigh 300 mg of pre-carbonized yeast and 600 mg of potassium chloride and mix them evenly. Activate the mixture at 900 °C in an argon atmosphere for 1 hour.

[0079] Add a prepared 1 mol / L nitric acid solution to the activated yeast, stir for 2 hours and filter. Wash the material with deionized water until the filtrate is neutral (pH=7). Then dry the material at 50°C for 24 hours to obtain yeast carbon-based yeast.

[0080] Weigh 20 mg of yeast carbon-based material and add it to 50 ml of isopropanol solution and sonicate to obtain a uniformly dispersed yeast carbon-based dispersion.

[0081] 0.2 mmol of cobalt sulfate and 0.8 mmol of o-phenanthroline were added to 50 ml of ethanol solution and stirred continuously to obtain a dispersion of the coordination compound formed by cobalt sulfate and o-phenanthroline.

[0082] The yeast carbon-based dispersion was added to the above solution, stirred at 60°C for 20 hours, and then centrifuged. The separated material was then dried at 60°C for 20 hours to obtain the precursor material.

[0083] Yeast-based carbon electrocatalysts loaded with cobalt nanoparticles were prepared by calcining the precursor material at 900℃ in a nitrogen atmosphere for 2 hours.

[0084] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. The application of yeast-based carbon electrocatalysts supported on cobalt nanoparticles, characterized in that, Used as an oxygen reduction catalyst; The yeast-based carbon electrocatalyst supported on cobalt nanoparticles was prepared through the following steps: (1) The yeast is heated at 200-500℃ for 1-3 hours to obtain yeast carbon, which is then thoroughly mixed with inorganic salt and calcined. The inorganic salt is calcined into a molten state, and the yeast carbon is etched into a porous carbon structure by the molten inorganic salt. In step (1), the inorganic salt is sodium carbonate, potassium carbonate, sodium chloride or potassium chloride. (2) The material obtained in step (1) is first acid-washed, then washed with deionized water, then dried and dispersed in an organic solvent; (3) Disperse the cobalt salt and nitrogen-containing chelating agent in an organic solvent, whereby the cobalt salt and nitrogen-containing chelating agent form a cobalt complex; then add the dispersion obtained in step (2) to allow the cobalt complex to be adsorbed and incorporated into the porous structure of yeast carbon. After centrifugation, the precipitate is collected and dried to obtain the precursor material. (4) The precursor material obtained in step (3) is calcined in a non-oxidizing protective atmosphere to pyrolyze the cobalt complex to obtain cobalt nanoparticles, that is, yeast carbon-based electrocatalyst loaded with cobalt nanoparticles. The yeast carbon and nitrogen-containing chelating agent provide abundant doped nitrogen elements. The loaded cobalt nanoparticles have strong interactions with nitrogen and carbon atoms, thereby adjusting the electronic structure of the doped carbon and increasing the adsorption energy of the catalyst for oxygen, which can effectively improve the catalytic performance.

2. The application as described in claim 1, characterized in that, In step (3), the nitrogen-containing chelating agent is o-phenanthroline, 2,2-bipyridine, or ethylenediamine.

3. The application as described in claim 1 or 2, characterized in that, The molar ratio of the cobalt salt to the nitrogen-containing chelating agent is 1:(1-4).

4. The application as described in claim 1, characterized in that, In step (1), the calcination temperature is 600-900℃ and the calcination time is 1-3 hours.

5. The application as described in claim 1, characterized in that, In step (4), the calcination temperature is 700-900℃ and the time is 2-4 hours.

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