Zinc-platinum alloy with high electro-catalytic oxygen reduction activity, preparation method and application

Abstract

The invention belongs to the technical field of electro-catalytic materials, and particularly relates to a zinc-platinum alloy with high electro-catalytic oxygen reduction activity, a preparation method and application. A nitrogen-doped carbon material obtained after ZIF-8 pyrolysis is used as a zinc source and a carrier, another metal source is chloroplatinic acid, an impregnation method and a thermal reduction method are combined to prepare the zinc-platinum alloy, Zn-N-C metal sites exist in the nitrogen-doped carbon material obtained after ZIF-8 pyrolysis, and the nitrogen-doped carbon material has the advantages of being large in specific surface area, loose and porous. In order to enable the ORR reaction to be carried out more efficiently, Zn-N-C sites obtained through ZIF-8 pyrolysis and metal Pt with ORR efficient four-electron transfer are fully utilized, Zn is selected due to the fact that the Zn is large in reserves, low in price and high in Pt layer adsorption stability, and ZnPt / N-C with excellent ORR performance is prepared.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials technology, specifically relating to a zinc-platinum alloy with high electrocatalytic oxygen reduction activity, its preparation method, and its application. Background Technology

[0002] The oxygen reduction reaction (ORR) is the primary cathode reaction in fuel cells and metal-air batteries, but its slow kinetics limit its widespread application. Platinum (Pt) is the most efficient electrocatalyst for ORR, with its ideal ORR reaction pathway involving four electron transfers, resulting in low energy loss and fewer intermediate products, leading to high efficiency. However, Pt suffers from high cost, material scarcity, and poor stability, necessitating the development of non-platinum catalysts or low-platinum alloy catalysts. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings and deficiencies of the existing technology, and to provide a zinc-platinum alloy with high electrocatalytic oxygen reduction activity, its preparation method and application.

[0004] The technical solution adopted in this invention is as follows: A method for preparing a zinc-platinum alloy with high electrocatalytic oxygen reduction activity includes the following steps: dispersing nitrogen-doped carbon material after ZIF-8 pyrolysis into a solvent, adding platinum metal salt, drying to obtain a solid, and then calcining the obtained solid in a mixed gas atmosphere of argon and hydrogen to obtain a zinc-platinum alloy.

[0005] Preferably, the nitrogen-doped carbon material after ZIF-8 pyrolysis is added to a solvent, ultrasonically dispersed, then transferred to a magnetic stirrer and stirred for 18-30 h, and then platinum metal salt is added.

[0006] Preferably, the platinum metal salt is added while sonicating, and after addition, stirring is continued for 8-16 hours.

[0007] Preferably, the molar ratio of Zn in the nitrogen-doped carbon material after ZIF-8 pyrolysis to Pt in the platinum metal salt is 1:0.7 to 1:1.2.

[0008] Preferably, the solid calcination reaction temperature is 650~850℃. o C.

[0009] Preferably, the solid calcination reaction time is 45 min to 1 h 10 min.

[0010] Preferably, the heating rate for solid calcination is 8~18 o C / min.

[0011] Preferably, the flow rate of argon is 90~98 sccm and the flow rate of hydrogen is 2~10 sccm.

[0012] The zinc-platinum alloy with high electrocatalytic oxygen reduction activity prepared by the method described above is an example of a zinc-platinum alloy with high electrocatalytic oxygen reduction activity.

[0013] The application of zinc-platinum alloy with high electrocatalytic oxygen reduction activity as an ORR electrocatalyst, as described above.

[0014] The beneficial effects of this invention are as follows: This invention utilizes nitrogen-doped carbon material obtained from the pyrolysis of ZIF-8 as a zinc source and support, with chloroplatinic acid as another metal source. A zinc-platinum alloy is prepared using a combination of impregnation and thermal reduction methods. The nitrogen-doped carbon material obtained from the pyrolysis of ZIF-8 contains Zn-NC metal sites, which have a large specific surface area and are porous. To make the ORR reaction more efficient, the Zn-NC sites from the ZIF-8 pyrolysis are fully utilized in conjunction with Pt, a metal exhibiting efficient four-electron transfer in ORR. Zn is chosen because of its large reserves, low price, and high adsorption stability on the Pt layer, resulting in a ZnPt / NC alloy with excellent ORR performance. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0016] Figure 1 The scanning electron microscope (SEM) image (a) and ORR polarization curve (b) of the ZnPt / NC prepared in Example 1 are shown.

[0017] Figure 2 ORR polarization curves of ZnPt / NC prepared under different parameter conditions: (a) ORR polarization curves of ZnPt / NC prepared under different temperature conditions; (b) ORR polarization curves of ZnPt / NC prepared under different feed ratio conditions; (c) ORR polarization curves of ZnPt / NC prepared under different reaction time conditions; (d) ORR polarization curves of ZnPt / NC prepared under different atmosphere conditions; (e) ORR polarization curves of ZnPt / NC prepared under different gas flow rates. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0019] Example 1: First, take 0.616 g of dimethylimidazole in a beaker, add 20 mL of methanol, and disperse by sonication to obtain solution A. Then, take 0.558 g of Zn(NO3)2 in a sealed glass bottle, add 20 mL of methanol, and disperse by sonication to obtain solution B. While sonicating, pour solution A into solution B, sonicate for 10 min, and immediately transfer to an oven at 35°C. o After static growth at C for 16 hours, the sample was removed and washed several times with methanol in a centrifuge to obtain a white solid, ZIF-8, which was then placed in an oven at 35°C. o Dry at 24 h at C, grind, and set aside. The prepared ZIF-8 is then subjected to a process at 1000 °C. o C. Reaction time is 3 hours, heating rate is 14 o Thermal decomposition was performed at C / min and an argon flow rate of 5 sccm. The zinc content in the nitrogen-doped carbon material after ZIF-8 pyrolysis was found to be 15%.

[0020] Take 30 mg of nitrogen-doped carbon material with a zinc content of 15% after ZIF-8 pyrolysis and place it in a 25 mL beaker. Disperse it ultrasonically for 20 min, then transfer it to a magnetic stirrer and stir for 24 h. While still ultrasonicating, add a certain volume of chloroplatinic acid at a Zn to Pt molar ratio of 1:1, and continue stirring for 12 h. Finally, transfer it to an oven at 80°C. o C. Dry and store for later use.

[0021] The obtained solid was placed in a porcelain boat and then placed in a quartz tube for calcination, with the temperature adjusted to 700°C. o C. Reaction time is 1 hour, heating rate is 14 o The reaction was carried out at a concentration of C / min and an argon flow rate of 95 sccm and a hydrogen flow rate of 5 sccm. After the reaction was naturally cooled to room temperature, a black solid was obtained.

[0022] 3 mg of black solid was placed in a small centrifuge tube, and 1000 μL of isopropanol and 500 μL of water were added respectively. After sonication for 40 min, 15 μL of 5% Nafion was added, and sonication was continued for another 30 min to obtain a uniformly dispersed ink. 20 μL of this ink was dropped onto the glassy carbon surface of the working electrode using a pipette, and the electrode was allowed to air dry naturally. After aging for 5 h, the working electrode was tested. The test results are as follows: Figure 1 As shown, its ORR is 0.928 V vs. RHE.

[0023] Example 2: Other conditions were the same as in Example 1, except that the temperature was set to 600. o C, 650 o C, 750 o C, 800 o C and 850o C. An electrocatalytic material was prepared. The obtained electrocatalytic material exhibits good catalytic performance, but its performance is not as good as that of Example 1, such as... Figure 2 (a).

[0024] Example 3: Other conditions were the same as in Example 1, except that the molar ratio of Zn to Pt was set to 1:0.7, 1:0.8, 1:0.9, 1:1.1, and 1:1.2, respectively, to prepare electrocatalytic materials. The obtained electrocatalytic materials exhibited good catalytic performance, but not as good as those in Example 1. Figure 2 (b).

[0025] Example 4: Other conditions were the same as in Example 1, with reaction times set to 45 min, 50 min, 55 min, 1 h 0.5 min, and 1 h 10 min, respectively, to prepare the electrocatalytic material. The obtained electrocatalytic material exhibited good catalytic performance, but its performance was not as good as that of Example 1. Figure 2 (c).

[0026] Example 5: Other conditions were the same as in Example 1, except that the heating rates were set to 8, 10, 12, 16, and 18, respectively. o The electrocatalytic material was prepared at a concentration of C / min. The obtained electrocatalytic material exhibits good catalytic performance, but its performance is not as good as that of Example 1. Figure 2 (e).

[0027] Example 6: Other conditions were the same as in Example 1, except that the argon gas flow rate was set to 90, 92, 94, 96, and 98 sccm, and the hydrogen gas flow rate was changed to 10, 8, 6, 4, and 2 sccm respectively, to prepare the electrocatalytic material. The obtained electrocatalytic material exhibited good catalytic performance, but its catalytic performance was not as good as that of Example 1. Figure 2 (d).

[0028] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a zinc-platinum alloy with high electrocatalytic oxygen reduction activity, characterized in that... Includes the following steps: Nitrogen-doped carbon material after ZIF-8 pyrolysis was dispersed in a solvent, platinum metal salt was added, and the mixture was dried to obtain a solid. The solid was then calcined in a mixed atmosphere of argon and hydrogen to obtain a zinc-platinum alloy.

2. The method for preparing a zinc-platinum alloy with high electrocatalytic oxygen reduction activity according to claim 1, characterized in that: The nitrogen-doped carbon material after ZIF-8 pyrolysis is added to a solvent, ultrasonically dispersed, and then transferred to a magnetic stirrer and stirred for 18-30 h before platinum metal salt is added.

3. The method for preparing a zinc-platinum alloy with high electrocatalytic oxygen reduction activity according to claim 2, characterized in that: Platinum metal salts were added while sonicating, and stirring continued for 8-16 hours after addition.

4. The method for preparing a zinc-platinum alloy with high electrocatalytic oxygen reduction activity according to claim 1, characterized in that: The molar ratio of Zn in the nitrogen-doped carbon material after ZIF-8 pyrolysis to Pt in the platinum metal salt is 1:0.7 to 1:1.

2.

5. The method for preparing a zinc-platinum alloy with high electrocatalytic oxygen reduction activity according to claim 1, characterized in that: The solid calcination reaction temperature is 650~850℃ o C.

6. The method for preparing a zinc-platinum alloy with high electrocatalytic oxygen reduction activity according to claim 1, characterized in that: The solid calcination reaction time is 45 min to 1 h 10 min.

7. The method for preparing a zinc-platinum alloy with high electrocatalytic oxygen reduction activity according to claim 1, characterized in that: The heating rate for solid calcination is 8~18 o C / min.

8. The method for preparing a zinc-platinum alloy with high electrocatalytic oxygen reduction activity according to claim 1, characterized in that: The flow rate of argon is 90~98 sccm, and the flow rate of hydrogen is 2~10 sccm.

9. The zinc-platinum alloy with high electrocatalytic oxygen reduction activity prepared by the method for preparing zinc-platinum alloy with high electrocatalytic oxygen reduction activity according to any one of claims 1-8.

10. The application of the zinc-platinum alloy with high electrocatalytic oxygen reduction activity as described in claim 9 as an ORR electrocatalyst.

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