Fullerene-based Mo2C / C60 electrocatalyst as well as preparation method and application thereof

Abstract

The invention discloses a fullerene-based Mo2C / C60 electrocatalyst and a preparation method and application thereof.The electrocatalyst is composed of fullerene and ammonium molybdate according to the mass ratio of (0.5-2): 1, the fullerene and the ammonium molybdate serve as a C source and a Mo source respectively, and a fullerene-based molybdenum carbide / fullerene composite material is formed. The preparation method comprises the following steps: preparing fullerene and ammonium molybdate into a mixture precursor by adopting a method of firstly dissolving, then dipping, drying and grinding; in a mixed atmosphere of hydrogen and argon, carrying out segmented high-temperature calcination on the mixture precursor to obtain a molybdenum carbide / fullerene carbon material; and carrying out acid pickling on the molybdenum carbide / fullerene carbon material to remove metal simple substances generated in the reaction, and finally drying to obtain the fullerene-based Mo2C / C60 electrocatalyst. The electrocatalyst provided by the invention has a large specific surface area and an electrochemical active area, and more active sites can be exposed, so that the electrocatalytic hydrogen evolution capacity of the catalyst is greatly enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalytic hydrogen production, and in particular to a fullerene-based Mo 2 C / C 60 Electrocatalyst and its preparation method and application. Background Art

[0002] Hydrogen energy has the characteristics of high energy density, high calorific value, clean and pollution-free, and high conversion efficiency, and is an ideal secondary energy source. The process of hydrogen production by electrolysis of water does not have CO 2 The emission of hydrogen and oxygen is only hydrogen and oxygen, which is considered to be the most promising green process for obtaining hydrogen energy. At present, precious metals such as Pt are the hydrogen evolution catalysts with the best comprehensive performance, but their low storage capacity and high cost limit their large-scale application. In order to develop low-cost and efficient water electrolysis catalysts, it is undoubtedly a reasonable and feasible strategy to select resource-rich, low-cost, and environmentally friendly non-precious metal catalysts, and to exert the synergistic coupling effect of multiple components to obtain excellent catalytic performance by regulating the chemical composition, atomic structure, and electronic structure of the metal / metal (hydride) oxide interface. To this end, it is of great significance to study an efficient, cheap, and environmentally friendly non-precious metal catalyst.

[0003] Since the rate-determining step reaction in alkaline electrohydrogen evolution is limited by the water dissociation reaction, carbides with water dissociation ability have entered the field of vision of researchers. Through theoretical calculations, researchers found that carbides have an electronic structure similar to that of platinum, and they may have very excellent catalytic activity in alkaline electrohydrogen evolution. After the efforts of researchers, carbides represented by molybdenum carbide were found to have very good catalytic activity in alkaline HER. With the development of modern science and technology and the information industry, traditional transition metal carbides can no longer meet people's needs. People need to put forward higher performance requirements and a more green and environmentally friendly development direction for carbides to meet the application requirements in harsh environments such as hydrogen storage and wind power generation. This requires that the hydrogen evolution performance of carbides also needs to be further improved. While meeting industrial requirements, better hydrogen evolution also means improving the industry competitiveness in the field of catalytic materials in my country.

[0004] However, from the perspective of catalyst design, Mo 2 C-based catalysts still have some fatal weaknesses. In the synthesis process of molybdenum carbide, it often undergoes a high-temperature reduction and carburization process, which will cause the material to sinter, resulting in the increase of material size and particle aggregation, and the collapse of the surface pore structure, resulting in a small specific surface area of ​​the catalyst, which is not conducive to the exposure of catalytic active sites. In addition, although Mo 2 The electronic structure of C is relatively close to that of Pt group metals, but theoretical calculations have found that its hydrogen adsorption energy is still relatively large, and there is still room for further optimization. Summary of the invention

[0005] The object of the present invention is to provide a fullerene-based Mo 2 C / C 60 An electrocatalyst and a preparation method and application thereof can solve the problem of molybdenum carbide particle aggregation existing in the preparation method of the prior art.

[0006] In one aspect of the present invention, the present invention provides a fullerene-based Mo 2 C / C 60 Electrocatalyst. According to an embodiment of the present invention, the electrocatalyst is composed of fullerene and ammonium molybdate in a mass ratio of (0.5-2):1, wherein the fullerene and ammonium molybdate serve as C source and Mo source, respectively, to form a molybdenum carbide / fullerene composite material with fullerene as the substrate.

[0007] In another aspect of the present invention, the present invention provides a fullerene-based Mo 2 C / C 60 Method for preparing an electrocatalyst. According to an embodiment of the present invention, the method comprises the following steps:

[0008] (1) preparing a mixture precursor of fullerene and ammonium molybdate by a method of first dissolving, then impregnating, drying and grinding;

[0009] (2) calcining the mixture precursor in stages at high temperature in a mixed atmosphere of hydrogen and argon to obtain a molybdenum carbide / fullerene carbon material;

[0010] (3) The molybdenum carbide / fullerene carbon material is acid-washed to remove the metal element generated by the reaction, and finally dried to obtain the fullerene-based Mo 2 C / C 60 Electrocatalyst.

[0011] In addition, according to the above embodiment of the present invention, a fullerene-based Mo 2 C / C 60 The method for preparing the electrocatalyst may also have the following additional technical features:

[0012] In some embodiments of the present invention, step (1) specifically includes the following steps: grinding ammonium molybdate and dissolving it in pure water to obtain an ammonium molybdate hexahydrate solution, grinding fullerene and pouring it into the ammonium molybdate hexahydrate solution, and then stirring and mixing overnight until the sample is completely dissolved, then heating and stirring to evaporate water, grinding, and obtaining a mixture precursor.

[0013] In some embodiments of the present invention, the stirring and mixing time is 6 to 8 hours, and the heating and stirring temperature is 60 to 70°C.

[0014] In some embodiments of the present invention, in step (2), the heating rate of the staged high-temperature calcination is 5-10°C / min, the first stage of high-temperature calcination is kept at 300°C for 2-3 hours, the second stage of high-temperature calcination is kept at 900-1100°C for 2-3 hours, and then the temperature is naturally lowered.

[0015] In some embodiments of the present invention, in step (2), the volume ratio of hydrogen to argon is in the range of 1:(19-24).

[0016] In some embodiments of the present invention, in step (3), the pickling solution is a 0.4-0.6 mol / L sulfuric acid solution, the pickling temperature is 75-80° C., and the pickling time is 4-6 h.

[0017] In some embodiments of the present invention, in step (3), the drying temperature is 60-80° C., and the drying time is 6-8 hours.

[0018] In another aspect of the present invention, the present invention provides a fullerene-based Mo 2 C / C 60 Application of electrocatalyst: According to an embodiment of the present invention, the electrocatalyst is used for electrocatalytic hydrogen evolution reaction in an electrolytic cell.

[0019] In addition, according to the above embodiment of the present invention, a fullerene-based Mo 2 C / C 60 The application of electrocatalysts may also have the following additional technical features:

[0020] In some embodiments of the present invention, the electrocatalyst is used to electrolyze water to generate hydrogen.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) Fullerenes have a highly symmetrical cage structure, which helps them maintain stable performance during electrocatalysis and facilitates heteroatom doping.

[0023] (2) Fullerene itself has good electrical conductivity, which helps to achieve rapid electron transfer during the electrocatalytic process and improve the catalytic efficiency.

[0024] (3) Fullerene-based Mo of the present invention 2 C / C 60 Electrocatalysts due to fullerenes (such as C 60 ) has a spherical cage-like structure, which can be used as a template or "cage" to provide physical confinement during the preparation of molybdenum carbide. This confinement effect can limit the growth of molybdenum carbide nanoparticles, thus overcoming the problem of molybdenum carbide particle aggregation, and the raw materials used are lower in cost than precious metals and are harmless to the environment and human body.

[0025] (4) Fullerene-based Mo of the present invention 2 C / C 60 The electrocatalyst has a large specific surface area and electrochemically active area, which can expose more active sites, greatly enhancing the electrocatalytic hydrogen evolution ability of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is the fullerene-based Mo in Example 1 of the present invention 2 C / C 60 Morphology of electrocatalysts;

[0027] Figure 2 XRD spectra of fullerene-based electrocatalysts at different ratios in Examples 1-3 and Comparative Examples 1-2 of the present invention, where the ratio in the figure is the mass ratio of fullerene to ammonium molybdate;

[0028] Figure 3 The LSV (Linear Sweep Voltammetry) diagram of the fullerene-based electrocatalysts at different ratios in Examples 1-3 and Comparative Examples 1-2 of the present invention, wherein the ratio in the diagram is the mass ratio of fullerene to ammonium molybdate;

[0029] Figure 4 is the fullerene-based Mo at different temperatures in Examples 1, 4-5 of the present invention 2 C / C 60 XRD spectrum of electrocatalyst, the temperature in the figure is the temperature of the second high-temperature calcination;

[0030] Figure 5 is the fullerene-based Mo at different temperatures in Examples 1, 4-5 of the present invention 2 C / C 60 The LSV (linear sweep voltammetry) diagram of the electrocatalyst, the temperature in the diagram is the temperature of the second high-temperature calcination stage. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] A fullerene-based Mo 2 C / C 60 The method for preparing an electrocatalyst comprises the following steps:

[0034] (1) Weigh 0.2 g of fullerene and 0.1 g of ammonium molybdate hexahydrate (the mass ratio of fullerene to ammonium molybdate is 2:1). Grind 0.1 g of ammonium molybdate hexahydrate and dissolve it in 20 mL of pure water to obtain an ammonium molybdate hexahydrate solution for standby use. Grind 0.2 g of fullerene and dissolve it in 20 mL of ammonium molybdate hexahydrate solution and stir for 6 h. Then heat the solution in a 60°C water bath until the water is completely volatilized, grind it, and obtain a mixture precursor.

[0035] (2) The precursor mixture is calcined in stages at high temperature in a gas mixture with a volume fraction of 5% hydrogen and 95% argon. The heating rate in the first stage is 10°C per minute, and then it is kept at 3000°C for 2 hours. The heating rate in the second stage is 5°C per minute. After keeping at 1000°C for 2 hours, the temperature is naturally lowered to obtain a molybdenum carbide / fullerene carbon material.

[0036] (3) The molybdenum carbide / fullerene carbon material was pickled with a 0.5 mol / L sulfuric acid solution, a pickling temperature of 80°C, a pickling speed of 500 rpm, and a pickling time of 4 h, and the fullerene-based Mo was obtained by filtration. 2 C / C 60 Electrocatalyst.

[0037] like Figure 1 High-resolution transmission electron microscopy images show that the prepared fullerene-based Mo 2 C / C 60 The electrocatalyst has irregularly shaped particles, which are formed molybdenum carbide particles, wherein the molybdenum carbide particles are uniformly grown on a substrate of five-membered ring fragments formed after calcining fullerene.

[0038] like Figure 2 The XRD spectrum shows that diffraction peaks appear at 2θ=34.3°, 37.9°, 52.1°, 61.5°, 69.5°, 74.6° and 75.5°, which is consistent with the standard spectrum of molybdenum carbide. Therefore, the raw materials and methods used in the present invention successfully generate Mo 2 C / C 60 Electrocatalytic materials.

[0039] like Figure 3 As shown, after testing, the fullerene-based Mo prepared according to the above steps 2 C / C 60 The electrocatalyst was tested for electrochemical performance (electrolyte was potassium hydroxide solution with pH = 1, and the reference electrode was Ag / AgCl). 2 At a current density of , its hydrogen evolution overpotential is 45mV.

[0040] Example 2

[0041] A fullerene-based Mo 2 C / C60 The preparation method of the electrocatalyst is different from that of Example 1 only in that the mass of ammonium molybdate hexahydrate in step (1) is 0.2 g, that is, the mass ratio of fullerene to ammonium molybdate is 1:1, and the remaining steps and parameters are the same.

[0042] like Figure 2 The XRD spectrum shows that diffraction peaks appear at 2θ=34.3°, 37.9°, 52.1°, 61.5°, 69.5°, 74.6° and 75.5°, which is consistent with the standard spectrum of molybdenum carbide. Therefore, the raw materials and methods used in the present invention successfully generate Mo 2 C / C 60 Electrocatalytic materials.

[0043] like Figure 3 As shown, after testing, the fullerene-based Mo prepared according to the above steps 2 C / C 60 The electrocatalyst was tested for electrochemical performance (electrolyte was potassium hydroxide solution with pH = 1, and the reference electrode was Ag / AgCl). 2 At a current density of , its hydrogen evolution overpotential is 107mV.

[0044] Example 3

[0045] A fullerene-based Mo 2 C / C 60 The method for preparing the electrocatalyst is different from that of Example 1 only in that the mass of ammonium molybdate hexahydrate in step (1) is 0.4 g, that is, the mass ratio of fullerene to ammonium molybdate is 1:2, and the remaining steps and parameters are the same.

[0046] like Figure 2 The XRD spectrum shows that diffraction peaks appear at 2θ=34.3°, 37.9°, 52.1°, 61.5°, 69.5°, 74.6° and 75.5°, which is consistent with the standard spectrum of molybdenum carbide. Therefore, the raw materials and methods used in the present invention successfully generate Mo 2 C / C 60 Electrocatalytic materials.

[0047] like Figure 3 As shown, after testing, the fullerene-based Mo prepared according to the above steps 2 C / C 60 The electrocatalyst was tested for electrochemical performance (electrolyte was potassium hydroxide solution with pH = 1, and the reference electrode was Ag / AgCl). 2 At a current density of , its hydrogen evolution overpotential is 111 mV.

[0048] Example 4

[0049] A fullerene-based Mo 2 C / C 60 The preparation method of the electrocatalyst is different from that of Example 1 only in that the second high-temperature calcination in step (2) is carried out at 900° C. for 2 h, and the remaining steps and parameters are the same.

[0050] like Figure 4 The XRD spectrum shows that diffraction peaks appear at 2θ=34.3°, 37.9°, 52.1°, 61.5°, 69.5°, 74.6° and 75.5°, which is consistent with the standard spectrum of molybdenum carbide. Therefore, the raw materials and methods used in the present invention successfully generate Mo 2 C / C 60 Electrocatalytic materials.

[0051] like Figure 5 As shown, after testing, the fullerene-based Mo prepared according to the above steps 2 C / C 60 The electrocatalyst was tested for electrochemical performance (electrolyte was potassium hydroxide solution with pH = 1, and the reference electrode was Ag / AgCl). 2 At a current density of , its hydrogen evolution overpotential is 91mV.

[0052] Example 5

[0053] A fullerene-based Mo 2 C / C 60 The preparation method of the electrocatalyst is different from that of Example 1 only in that the second high-temperature calcination in step (2) is carried out at 1100° C. for 2 h, and the remaining steps and parameters are the same.

[0054] like Figure 4 The XRD spectrum shows that diffraction peaks appear at 2θ=34.3°, 37.9°, 52.1°, 61.5°, 69.5°, 74.6° and 75.5°, which is consistent with the standard spectrum of molybdenum carbide. Therefore, the raw materials and methods used in the present invention successfully generate Mo 2 C / C 60 Electrocatalytic materials.

[0055] like Figure 5 As shown, after testing, the fullerene-based Mo prepared according to the above steps 2 C / C 60 The electrocatalyst was tested for electrochemical performance (electrolyte was potassium hydroxide solution with pH = 1, and the reference electrode was Ag / AgCl). 2 At a current density of , its hydrogen evolution overpotential is 65mV.

[0056] Comparative Example 1

[0057] A method for preparing a fullerene-based electrocatalyst, which differs from Example 1 only in that the mass of ammonium molybdate hexahydrate in step (1) is 0.05 g, that is, the mass ratio of fullerene to ammonium molybdate is 4:1, and the remaining steps and parameters are the same.

[0058] like Figure 2 The XRD spectrum shows that only the amorphous peak of the carbon material appears in the figure. Therefore, when the mass ratio of fullerene to ammonium molybdate is 4:1, molybdenum carbide cannot be formed.

[0059] like Figure 3 As shown, the catalyst prepared according to the above steps was tested. In the electrochemical performance test (the electrolyte was a potassium hydroxide solution with a pH of 1, and the reference electrode was Ag / AgCl), the 2 At a current density of , its hydrogen evolution overpotential is 97mV.

[0060] Comparative Example 2

[0061] A method for preparing a fullerene-based electrocatalyst, which differs from Example 1 only in that the mass of ammonium molybdate hexahydrate in step (1) is 0.067 g, that is, the mass ratio of fullerene to ammonium molybdate is 3:1, and the remaining steps and parameters are the same.

[0062] like Figure 2 The XRD spectrum shows that only the amorphous peak of the carbon material appears in the figure. Therefore, when the mass ratio of fullerene to ammonium molybdate is 3:1, molybdenum carbide cannot be formed.

[0063] like Figure 3 As shown, the catalyst prepared according to the above steps was tested. In the electrochemical performance test (the electrolyte was a potassium hydroxide solution with a pH of 1, and the reference electrode was Ag / AgCl), the 2 At a current density of , its hydrogen evolution overpotential is 87mV.

[0064] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A fullerene-based Mo2C / C 60 An electrocatalyst characterized by: The electrocatalyst is composed of fullerene and ammonium molybdate in a mass ratio of (0.5-2):

1. The fullerene and ammonium molybdate serve as a C source and a Mo source respectively to form a molybdenum carbide / fullerene composite material with fullerene as a substrate.

2. A fullerene-based Mo2C / C as claimed in claim 1 60 A method for preparing an electrocatalyst, characterized in that: The following steps are involved: (1) preparing a mixture precursor of fullerene and ammonium molybdate by a method of first dissolving, then impregnating, drying and grinding; (2) calcining the mixture precursor in stages at high temperature in a mixed atmosphere of hydrogen and argon to obtain a molybdenum carbide / fullerene carbon material; (3) The molybdenum carbide / fullerene carbon material is acid-washed to remove the metal element generated by the reaction, and finally dried to obtain the fullerene-based Mo2C / C 60 Electrocatalyst.

3. A fullerene-based Mo2C / C according to claim 2 60 A method for preparing an electrocatalyst, characterized in that: Step (1) specifically includes the following steps: grinding ammonium molybdate and dissolving it in pure water to obtain an ammonium molybdate hexahydrate solution; grinding fullerene and pouring it into the ammonium molybdate hexahydrate solution; stirring and mixing overnight until the sample is completely dissolved; then heating and stirring to evaporate water; grinding to obtain a mixture precursor.

4. A fullerene-based Mo2C / C according to claim 3 60 A method for preparing an electrocatalyst, characterized in that: The stirring and mixing time is 6 to 8 hours, and the heating and stirring temperature is 60 to 70°C.

5. A fullerene-based Mo2C / C according to claim 2 60 A method for preparing an electrocatalyst, characterized in that: In step (2), the heating rate of the staged high-temperature calcination is 5-10°C / min, the first stage of high-temperature calcination is kept at 300°C for 2-3 hours, the second stage of high-temperature calcination is kept at 900-1100°C for 2-3 hours, and then the temperature is naturally reduced.

6. A fullerene-based Mo2C / C according to claim 2 60 A method for preparing an electrocatalyst, characterized in that: In step (2), the volume ratio of hydrogen to argon is in the range of 1:(19-24).

7. A fullerene-based Mo2C / C according to claim 2 60 A method for preparing an electrocatalyst, characterized in that: In step (3), the pickling solution is a 0.4-0.6 mol / L sulfuric acid solution, the pickling temperature is 75-80° C., and the pickling time is 4-6 h.

8. A fullerene-based Mo2C / C according to claim 2 60 A method for preparing an electrocatalyst, characterized in that: In step (3), the drying temperature is 60 to 80° C. and the drying time is 6 to 8 hours.

9. A fullerene-based Mo2C / C as claimed in claim 1 60 Application of electrocatalysts, characterized by: The electrocatalyst is used for electrocatalytic hydrogen evolution reaction in an electrolytic cell.

10. A fullerene-based Mo2C / C according to claim 9 60 Application of electrocatalysts, characterized by: The electrocatalyst is used for electrolyzing water to generate hydrogen.

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