Preparation of vanadium carbide hollow nanosphere loaded platinum cluster catalyst and application of vanadium carbide hollow nanosphere loaded platinum cluster catalyst in hydroxide reaction

Abstract

The invention discloses a preparation method of a vanadium carbide hollow nanosphere loaded platinum cluster catalyst and an application of the vanadium carbide hollow nanosphere loaded platinum cluster catalyst in a hydroxide reaction, relates to the technical field of electrocatalysis, and provides a preparation method of vanadium carbide with a specific hollow nanosphere structure and a loaded platinum cluster of the vanadium carbide hollow nanosphere structure compared with the prior art. According to the present invention, the controllable nanosphere morphology provides the wide application prospect, the high catalytic activity and the high stability in the hydrogen oxidation reaction are provided, the catalyst is especially suitable for the hydrogen oxidation reaction in the alkaline medium, and the feasible guidance can be provided for the development of the efficient vanadium-based electrochemical catalyst.

Description

Technical Field

[0001] The invention relates to the technical field of electrocatalysis, and in particular to the preparation of a vanadium carbide hollow nanosphere-loaded platinum cluster catalyst and its application in hydrogen oxidation reactions. Background Art

[0002] With the continuous development of economy, the aggravation of energy shortage and environmental pollution, it is of great significance to develop clean and sustainable energy paths. Hydrogen energy, as a green and efficient secondary energy, has the characteristics of abundant reserves, diverse sources, low carbon and environmental protection. It is the most promising sustainable energy in the 21st century. In the past few years, proton exchange membrane fuel cells (PEMFCs) have developed rapidly.

[0003] Alkaline anion exchange membrane fuel cells (AEMFCs) have a similar cell structure to PEMFCs, but compared with PEMFCs, AEMFCs have more obvious advantages. Nevertheless, the activity of AEMFCs in the anodic hydrogen oxidation reaction (HOR) in alkaline media is still limited by the slow reaction kinetics, which show two to three orders of magnitude slower kinetics in alkaline media compared to acidic media. In order to speed up the reaction kinetics and reduce the reaction energy consumption, platinum group precious metal Ir, Ru, Pt, Pd catalysts still have good catalytic performance.

[0004] For supported catalysts, the choice of support material is of great significance to improve the electrocatalytic performance, because the interaction between metal and support can greatly adjust the electronic structure of supported metal and improve its intrinsic activity. Transition metal carbide materials have attracted extensive attention as catalyst supports due to their diverse composition and structure, flexible adjustability, low cost and ease of synthesis. The electronic and geometric effects generated by the interaction between metal and transition metal carbide support are responsible for the activity and stability of the catalyst. It can be seen that designing nanostructured transition metal carbides with customized morphology has been proven to be an effective strategy to address these problems.

[0005] However, existing vanadium carbide catalysts lack the function of customizing a fixed shape, resulting in the shape of the catalyst output being unable to adapt to various usage scenarios. Therefore, it is particularly important to develop a vanadium carbide catalyst that can customize the shape of the catalyst for the use of dry carrier material catalysts. This not only helps to evaluate the product life, but also provides data support for improving design and improving product quality. Summary of the invention

[0006] 1. Technical issues to be solved

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a preparation method of a vanadium carbide hollow nanosphere loaded with a platinum cluster catalyst and its application in a hydrogen oxidation reaction. The present invention not only realizes the preparation of a vanadium carbide catalyst, but also realizes hollow nanospheres by physical and chemical methods, and the size of the nanospheres can be customized.

[0008] 2. Technical solution

[0009] To solve the above problems, the present invention adopts the following technical solutions:

[0010] The preparation of vanadium carbide hollow nanosphere-supported platinum cluster catalyst and its application in hydrogen oxidation reaction are characterized by comprising the following steps:

[0011] (1) dissolving a vanadium source in a solvent, then adding dopamine hydrochloride, and dropping ammonia water to adjust the pH value, stirring the reaction, centrifuging, separating, washing, and drying to obtain a precursor;

[0012] The precursor prepared above is subjected to Joule heat shock in an inert gas atmosphere (the role and beneficial effects of Joule heat and the specific shock method and how to shock will be briefly introduced later) to obtain vanadium carbide hollow nanospheres;

[0013] The prepared vanadium carbide hollow nanospheres are loaded with metal platinum using a platinum source, and calcined in an argon-hydrogen atmosphere to obtain platinum-loaded vanadium carbide hollow nanospheres.

[0014] As a preferred embodiment of the present invention, the vanadium source is ammonium metavanadate or its hydrate.

[0015] As a preferred solution of the present invention, the solvent is deionized water, and its pH value is 8.0-9.0.

[0016] As a preferred embodiment of the present invention, the mass ratio of the vanadium source to dopamine hydrochloride is (1-3):1.

[0017] As a preferred solution of the present invention, the current of the Joule thermal shock is 65-70A, and the shock time is 20s.

[0018] As a preferred embodiment of the present invention, the platinum source is chloroplatinic acid, the metal platinum is loaded by an impregnation method, and the loading amount of the platinum is 3-4%.

[0019] As a preferred embodiment of the present invention, the content of hydrogen in the argon-hydrogen atmosphere is 5%, the calcination temperature is 300° C., and the calcination time is 2 to 2.5 hours.

[0020] As a preferred embodiment of the present invention, the electrocatalytic hydrogen oxidation reaction is a hydrogen oxidation reaction in an alkaline medium using 0.1 M KOH as an electrolyte.

[0021] 3. Beneficial effects

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] (1) The present invention provides a method for preparing vanadium carbide having a specific hollow nanosphere structure and its loaded platinum clusters. The controllable nanosphere morphology makes it have a relatively broad application prospect.

[0024] (2) The present invention exhibits high catalytic activity and stability in hydrogen oxidation reactions, and is particularly suitable for hydrogen oxidation reactions in alkaline media, and can provide practical guidance for the development of efficient vanadium-based electrochemical catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 and Figure 2 The structural characterization results of the Pt / VC sample prepared in Example 1 of the present invention: X-ray diffraction pattern; scanning electron microscope image;

[0026] Figure 3-Figure 8 Performance test results of the Pt / VC sample prepared in Example 1 of the present invention and commercial Pt / C in the electrocatalytic hydrogen oxidation reaction:

[0027] in:

[0028] Figure 3 HOR polarization curves at different rotation speeds in H2-saturated 0.1 M KOH electrolyte;

[0029] Figure 4 Koutecky-Levich plot obtained at 50 mV overpotential;

[0030] Figure 5 is the HOR Tafel diagram;

[0031] Figure 6 HOR polarization curves at 1600 rpm in H2-saturated 0.1 M KOH electrolyte;

[0032] Figure 7 Comparison of HOR catalytic activity before and after 1000 CV cycles at 50 mV overpotential and 1600 rpm;

[0033] Figure 8 Current-time plot at 50 mV overpotential. DETAILED DESCRIPTION

[0034] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments and diagrams.

[0035] The present invention provides a method for preparing platinum-loaded vanadium carbide hollow nanospheres, comprising the following steps:

[0036] (1) dissolving vanadate in a solvent, then adding dopamine hydrochloride, and dropping ammonia water to adjust the pH value, stirring the reaction, centrifuging, separating, washing, and drying to obtain a precursor;

[0037] (2) subjecting the precursor prepared above to Joule thermal shock in an inert gas atmosphere to obtain vanadium carbide hollow nanospheres;

[0038] (3) Using a platinum source to load metal platinum on the prepared vanadium carbide hollow nanospheres, and calcining them in an argon-hydrogen atmosphere to obtain platinum-loaded vanadium carbide hollow nanospheres.

[0039] Preferably, the vanadate is ammonium metavanadate.

[0040] Preferably, the solvent is deionized water.

[0041] Preferably, the pH value is 8.0-9.0.

[0042] Preferably, the mass ratio of the vanadate to dopamine hydrochloride is (1-3):1.

[0043] Preferably, the current of the Joule thermal shock is 65-70V, and the shock time is 20s.

[0044] Preferably, the platinum source is chloroplatinic acid. Other platinum sources may also be used as precursors of metallic platinum.

[0045] Preferably, the metal platinum is loaded by an impregnation method.

[0046] Preferably, the loading amount of platinum is 3-4%.

[0047] Preferably, the content of hydrogen in the argon-hydrogen atmosphere is 5%.

[0048] Preferably, the calcination temperature is 300° C. and the calcination time is 2 to 2.5 hours.

[0049] In step (1), the vanadate anion (VO3 - ) rapidly chelates with dopamine to form a V-polydopamine (V-PDA) precursor; in step (2), Joule thermal shock is performed in a nitrogen atmosphere based on the morphology of the precursor to obtain vanadium carbide having a hollow nanosphere structure; and in step (3), vanadium carbide hollow nanospheres loaded with metal platinum are synthesized.

[0050] The present invention also provides platinum-loaded vanadium carbide hollow nanospheres prepared according to the above-mentioned preparation method.

[0051] The present invention further provides the use of the aforementioned platinum-loaded vanadium carbide hollow nanospheres in an electrocatalytic hydrogen oxidation reaction.

[0052] Preferably, the electrocatalytic hydrogen oxidation reaction is a hydrogen oxidation reaction in an alkaline medium using 0.1 M KOH as an electrolyte.

[0053] Example 1

[0054] Preparation of platinum-loaded vanadium carbide nanoflower balls:

[0055] (1) Dissolve 240 mg of ammonium metavanadate in 50 mL of deionized water, then add 200 mg of dopamine hydrochloride, continue stirring for 1 hour, and slowly add 0.4 mL of ammonia water, adjust the pH value to 8.0-9.0, stir the reaction for 12 hours, centrifuge with water and ethanol, separate, wash, and freeze-dry to obtain the precursor V-PDA.

[0056] (2) 50 mg of the V-PDA prepared above was placed in a carbon boat and subjected to shock at a current of 68 A for 20 s in a nitrogen atmosphere to obtain vanadium carbide hollow nanospheres, which were recorded as VC.

[0057] (3) VC was mixed with water and ultrasonically homogenized, and then chloroplatinic acid was added, and the mixture was heated on a hot plate and evaporated to dryness, and then calcined at 300° C. for 2 h in an argon-hydrogen atmosphere (hydrogen content was 5%) to obtain platinum-loaded vanadium carbide hollow nanospheres, which were recorded as Pt / VC. The platinum loading was 4%.

[0058] The structure of the Pt / VC sample prepared in Example 1 was characterized. Figure 1 , Figure 2 .

[0059] Figure 1 All the diffraction peaks in the graph correspond to the diffraction peaks of pure VC. After VC is loaded with Pt, the diffraction peaks are not shifted compared with the pure phase, and no peaks related to platinum clusters appear, which shows that the loading amount of platinum is low. Figure 2 It shows that the Pt / VC sample has a hollow nanosphere structure morphology;

[0060] Example 2

[0061] Study on the application of the Pt / VC sample prepared in Example 1 as a catalyst in electrocatalytic hydrogen oxidation:

[0062] The HOR electrocatalytic test was carried out on an electrochemical workstation using a standard three-electrode system. A 1M KOH solution filled with hydrogen was used as the electrolyte, a rotating disk electrode (RDE) modified with Pt / VC was used as the working electrode (4 mg of the Pt / VC sample prepared in Example 1 was dispersed in 1000 μL ethanol containing 40 uL 5wt% Nafion, and the ink was prepared by ultrasonication for 1 h; then 7.5 μL of the ink was dropped onto the polished rotating disk electrode to obtain the working electrode), a platinum wire was used as the counter electrode, and a Hg / HgO electrode was used as the reference electrode.

[0063] At the same time, a control example was set up in which commercial Pt / C was used as a catalyst to replace Pt / VC to prepare a working electrode. The Pt content in the Pt / C was 20%, and the other conditions were the same as above.

[0064] like Figure 3 and Figure 4 As shown, there is a linear relationship between the kinetic current density j and ω1 / 2 of RDE at an overpotential of 50 mV. The fitting straight line is expressed by the Koutecky-Levich equation with a slope of 4.78 cm2·mA-1·s-1 / 2, which is close to the theoretical value (4.87 cm2·mA-1·s-1 / 2 for two-electron HOR).

[0065] from Figure 5 and Figure 6 It can be seen that the HOR catalytic activity of Pt / VC in alkaline medium is significantly better than that of Pt / C.

[0066] from Figure 7 It can be seen that Pt / VC has extremely high stability in alkaline medium.

[0067] from Figure 8 It can be seen that the HOR catalytic activity of Pt / VC in alkaline medium can remain stable within 24 h.

[0068] In summary, the HOR catalytic activity of the Pt / VC prepared in the present invention in alkaline medium is better than that of the commercial Pt / C catalyst and has good stability.

[0069] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a vanadium carbide hollow nanosphere-supported platinum cluster catalyst, characterized in that: The following steps are involved: (1) dissolving a vanadium source in a solvent, then adding dopamine hydrochloride, and dropping ammonia water to adjust the pH value, stirring the reaction, centrifuging, separating, washing, and drying to obtain a precursor; The precursor prepared above is subjected to Joule heat shock in an inert gas atmosphere (the role and beneficial effects of Joule heat and the specific shock method and how to shock will be briefly introduced later) to obtain vanadium carbide hollow nanospheres; The prepared vanadium carbide hollow nanospheres are loaded with metal platinum using a platinum source, and calcined in an argon-hydrogen atmosphere to obtain platinum-loaded vanadium carbide hollow nanospheres.

2. The preparation method according to claim 1, characterized in that: The vanadium source is ammonium metavanadate or its hydrate.

3. The preparation method according to claim 1, characterized in that: The solvent is deionized water, and the pH value is 8.0-9.

0.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the vanadium source to dopamine hydrochloride is (1-3):

1.

5. The preparation method according to claim 1, characterized in that: The Joule thermal shock current is 65-70A, and the shock time is 20s.

6. The preparation method according to claim 1, characterized in that: The platinum source is chloroplatinic acid, the metal platinum is loaded by an impregnation method, and the loading amount of the platinum is 3-4%.

7. The preparation method according to claim 1, characterized in that: The content of hydrogen in the argon-hydrogen atmosphere is 5%, the calcination temperature is 300° C., and the calcination time is 2 to 2.5 hours.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The obtained platinum-loaded vanadium carbide hollow nanospheres.

9. The vanadium carbide hollow nanosphere-supported platinum cluster catalyst according to claim 8, characterized in that: The invention relates to an application of a catalyst in an electrocatalytic hydrogen oxidation reaction, wherein the electrocatalytic hydrogen oxidation reaction is a hydrogen oxidation reaction in an alkaline medium using 0.1M KOH as an electrolyte.

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