A method for preparing a platinum-based alloy rare earth metal oxide fuel cell anode catalyst

Abstract

The application relates to a preparation method of a platinum-based alloy rare earth metal oxide fuel cell anode catalyst, and relates to a preparation method of a platinum-based alloy oxide fuel cell catalyst, which aims to solve the technical problems of low catalytic activity and easy carbon monoxide poisoning of the existing methanol fuel cell anode catalyst. The method comprises the following steps: firstly, preparing a CeO2 catalyst carrier material by using a hydrothermal synthesis method; then mixing a corresponding Pt, Sn and Cu precursor solution used for preparing a PtSnCu alloy with the CeO2 catalyst carrier material to perform oil bath heating reaction; and finally, separating, washing and drying to obtain the catalyst PtSnCu / CeO2. The initial capacity of the catalyst in an acid electrolyte is 1010.5-1163.3 mA mg Pt ‑1 , and the capacity after 500 cycles is 680.65-820.4 mA mg Pt ‑1 , the retention rate is 67.4%-70.5%, and the catalyst can be used in the field of methanol fuel cells.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of material synthesis, and relates to a preparation method of a platinum-based alloy oxide fuel cell catalyst BACKGROUND

[0002] Compared with hydrogen fuel cells, direct methanol fuel cells (DMFC) have the advantages of low temperature, fast start, clean fuel, simple structure, etc., and have broad application prospects in portable electronic products. Methanol fuel cells are expected to become a new type of high-efficiency fuel cell due to their low fuel price, high energy conversion rate, and freedom from Carnot cycle limitations.

[0003] The anode of a methanol fuel cell needs to have good oxygen reduction activity and durability. At present, platinum, platinum alloys, metal oxides, etc. are the most widely studied catalyst materials for methanol fuel cells. Compared with other materials, platinum alloy catalysts are of great concern due to their high catalytic activity, good stability, and relatively low price. However, MOR-type CO intermediates are prone to poisoning on the Pt surface, which is an important factor restricting the catalytic performance of platinum-based catalysts.

[0004] The article "Pt-Sn-Cu Octapod Metal Nanoframes Promote Ethanol Oxidation" published in 2024 ADVANCED MATERIALS, Vol. 36, No. 21, pages 2311731, starts from typical PtCu nanocrystals, uses atomic Sn diffusion strategy to construct clear Pt 47 Sn 12 Cu 41 high refractive index nanoframes to promote ethanol oxidation. As an ethanol oxidation catalyst, the material has a catalytic activity of 3.10 Amg 47 Sn 12 Cu 41 octapod metal nanoframes. The material has a catalytic activity of 3.10 Amg -1 Pt However, it can also promote the cleavage and oxidation of toxic CO intermediates, but has limited resistance to CO poisoning. SUMMARY

[0005] The present application is to solve the technical problems of low catalytic activity and easy carbon monoxide poisoning of existing methanol fuel cell anode catalysts, and provides a preparation method of a platinum-based alloy rare earth metal oxide fuel cell anode catalyst. The present application has prepared a high-efficiency bifunctional catalyst material PtSnCu / CeO2 with good electrochemical performance and strong resistance to CO poisoning.

[0006] The preparation method of the platinum-based alloy rare earth metal oxide fuel cell anode catalyst of the present application is carried out in the following steps:

[0007] I. Prepare the CeO2 catalyst carrier material by hydrothermal synthesis method:

[0008] (1) adding sodium chloride and sodium hydroxide into distilled water, stirring to be uniform, to obtain solution A; adding cerium nitrate into water, stirring to be uniform, to obtain solution B; then adding solution B into solution A, stirring to make them mix uniformly; to obtain a mixed solution;

[0009] (2) transferring the mixed solution into a polytetrafluoroethylene-lined hydrothermal kettle, placing the hydrothermal kettle in a forced air drying oven, and keeping the temperature at 150-190 ℃ for 12-26 h to carry out hydrothermal reaction; after the reaction is completed, centrifugally separating the solid phase, and then washing, vacuum drying, to obtain a CeO2 precursor;

[0010] (3) grinding the CeO2 precursor, and then placing it into a porcelain boat, and then placing the porcelain boat into a tube furnace with argon, and heating to 400-900 ℃ to calcine for 2-6 h, and then cooling, to obtain a CeO2 catalyst carrier material;

[0011] II. mixing the corresponding Pt, Sn and Cu salt solutions used for preparing the PtSnCu alloy with the CeO2 catalyst carrier material, and then adding ethylene glycol and distilled water, and ultrasonically mixing them to be uniform, to obtain a precursor solution; placing the precursor solution into an oil bath, and oil-bathing at 120-160 ℃ for 1-4 h; centrifugally separating the solid phase, and then washing, vacuum drying, to obtain a platinum-based alloy rare earth metal oxide fuel cell anode catalyst, denoted as PtSnCu / CeO2.

[0012] Further, the hydrothermal treatment in step I (2) is at 180 ℃ for 24 h.

[0013] Further, the vacuum drying in step I (2) is carried out in a vacuum drying oven at a temperature of 60-70 ℃ for 8-12 h.

[0014] Further, the calcination temperature in step I (3) is 600 ℃, and the calcination time is 4 h.

[0015] Further, the oil-bathing temperature in step II is 140 ℃, and the oil-bathing time is 2 h. Under this condition, the one-pot reduction method can make the PtSnCu alloy uniformly reduced on the CeO2 catalyst carrier, and improve the methanol oxidation activity of the catalyst.

[0016] The present application adjusts the electronic structure of the PtSnCu catalyst by doping the rare earth element Ce (1.12) (relative to the Pauling electronegativity scale) with low electronegativity, and improves the battery electrochemical performance. In the PtSnCu / CeO2 of the present application, the significant difference in electronegativity between the Ce element and Pt (2.28) leads to strong electronic interaction between Ce and Pt, and in addition, CeO2 as a Ce3+ / Ce 4+ The CeO2 has high oxygen storage capacity, can effectively react with oxygen transmission and decomposition of intermediate products in the process, and further enhances the performance of the catalyst. The PtSnCu / CeO2 has great catalytic capacity for CO oxidation. The initial capacity of the catalyst in the acidic electrolyte is 1010.5~1163.3 mA mg Pt -1 After 500 cycles, the capacity retention rate is 67.4 %~70.5 %, and the catalyst has excellent stability and high CO tolerance in the acidic medium, relatively low cost, and can improve the stability and CO poisoning resistance of the methanol fuel cell. Pt -1 After 500 cycles, the capacity retention rate is 67.4 %~70.5 %, and the catalyst has excellent stability and high CO tolerance in the acidic medium, relatively low cost, and can improve the stability and CO poisoning resistance of the methanol fuel cell. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The XRD pattern of the CeO2 catalyst carrier material prepared in step one of Example 1;

[0018] Figure 2 The XRD pattern of the PtSnCu / CeO2 prepared in Example 1 and the PtSnCu / C prepared in Comparative Example 1;

[0019] Figure 3 The scanning electron microscope (SEM) image of the PtSnCu / CeO2 prepared in Example 1;

[0020] Figure 4 The electrochemical impedance spectroscopy (EIS) image of the PtSnCu / CeO2 catalyst prepared in Example 1, the PtSnCu / C prepared in Comparative Example 1, and the commercial Pt / C;

[0021] Figure 5 The cycle performance curve of the PtSnCu / CeO2 catalyst prepared in Example 1, the PtSnCu / C prepared in Comparative Example 1, and the commercial Pt / C. DETAILED DESCRIPTION

[0022] The application will be further described below in combination with specific examples and corresponding drawings.

[0023] Example 1: This example is a preparation method of a platinum-based alloy rare earth metal oxide fuel cell anode catalyst, which is carried out according to the following steps:

[0024] I. Preparation of CeO2 catalyst carrier material by hydrothermal synthesis method:

[0025] (1) 1 g of sodium chloride and 7.2 g of sodium hydroxide were added to 20 mL of distilled water, and stirred to obtain solution A; 0.652 g of cerium nitrate was added to 10 mL of water, and stirred to obtain solution B; then solution B was slowly added to solution A, and stirred for 30 min to obtain a mixture;

[0026] (2) The mixture was transferred to a 100 mL Teflon-lined autoclave, and the autoclave was placed in a drying oven, and hydrothermal reaction was carried out at 180 ℃ for 24 h; after the reaction was completed, the solid phase was separated by centrifugation, and then washed with a 1:1 mixture of water and ethanol three times, and dried in a vacuum drying oven at 60 ℃ for 12 h to obtain a CeO2 precursor;

[0027] (3) The CeO2 precursor was ground and placed in a porcelain boat, and then the porcelain boat was placed in a tube furnace with argon, and calcined at 600 ℃ for 4 h, and then cooled to obtain a CeO2 catalyst support material;

[0028] II. 1.335 mL of a chloroplatinic acid solution with a concentration of 0.0192 M, 10 mg of copper chloride, 0.54 mL of stannous chloride with a concentration of 0.021 M, and 20 mg of the CeO2 catalyst support material were added to a round-bottom flask, and then 30 mL of ethylene glycol and 20 mL of ultrapure water were added, and ultrasonic treatment was performed for 1 h to obtain a precursor solution; the precursor solution was placed in an oil bath, and oil bath treatment was performed at 140 ℃ for 2 h; the solid phase was separated by centrifugation, and then washed with ethanol three times, and dried in a vacuum drying oven at 60 ℃ for 12 h to obtain a platinum-based alloy rare earth metal oxide fuel cell catalyst material, which is denoted as PtSnCu / CeO2.

[0029] Comparative Example 1: In this comparative example, a catalyst PtSnCu / C catalyst was prepared, and the specific steps were as follows:

[0030] I. 1.335 mL of a chloroplatinic acid solution with a concentration of 0.0192 M, 10 mg of copper chloride, 0.54 mL of stannous chloride with a concentration of 0.021 M, and 20 mg of carbon powder were added to a round-bottom flask, and then 30 mL of ethylene glycol and 20 mL of ultrapure water were added, and ultrasonic treatment was performed for 1 h to obtain a precursor solution; the precursor solution was placed in an oil bath, and oil bath treatment was performed at 140 ℃ for 2 h; the solid phase was separated by centrifugation, and then washed with ethanol three times, and dried in a vacuum drying oven at 60 ℃ for 12 h to obtain a catalyst PtSnCu / C.

[0031] The XRD pattern of the CeO2 catalyst support material prepared in Step I of Example 1 is shown in FIG. 1. Figure 1 As can be seen from the figure, the CeO2 catalyst support was successfully synthesized, and it can also be seen that the crystallinity of the CeO2 catalyst support material is high.

[0032] XRD patterns of PtSnCu / CeO2 prepared in Example 1 and PtSnCu / C prepared in Comparative Example 1 are shown in FIG. 1, from which it can be seen that the peak of 39.8° Pt (111) is positively shifted, proving the synthesis of the alloy. Figure 2 Figure 2

[0033] The scanning electron microscope (SEM) image of PtSnCu / CeO2 prepared in Example 1 is shown in FIG. 2, from which it can be seen that PtSnCu / CeO2 is composed of PtSnCu alloy and hexahedral CeO2 support. The active components such as Pt, Sn and Cu are highly dispersed on the surface of the CeO2 support, increasing the number and utilization of active sites. The synergistic effect of CeO2 and PtSnCu nanoparticles can promote the adsorption of OH, promote the removal of adjacent CO, stabilize the structure of the active components, and improve the methanol oxidation activity of the catalyst. Figure 3 Figure 3

[0034] The PtSnCu / CeO2 catalyst prepared in Example 1, the PtSnCu / C prepared in Comparative Example 1 and the commercial Pt / C were simultaneously subjected to electrochemical performance testing. The method was as follows: 2 mg of catalyst was placed in a 5 ml vial, 2 ml of anhydrous ethanol was added, and ultrasonic treatment was performed for 30 min. 10 ul of the mixed solution was coated on a glassy carbon electrode (GC, inner diameter 4 mm), then 5 ul of Nafion solution was coated and allowed to dry naturally. CHI750E electrochemical workstation was used for electrochemical analysis. In a three-electrode system, the glassy carbon electrode was used as the working electrode, the Hg / Hg2SO4 electrode was used as the reference electrode, and the platinum sheet was used as the counter electrode. The test was performed in 0.5 M H2SO4 + 0.5 M CH3OH electrolyte at room temperature (scan rate: 50 mV / s).

[0035] The electrochemical impedance spectroscopy (EIS) curves of the PtSnCu / CeO2 catalyst prepared in Example 1, the PtSnCu / C prepared in Comparative Example 1 and the commercial Pt / C were tested, as shown in FIG. 3, from which it can be seen that PtSnCu / CeO2 has the lowest charge transfer resistance, also indicating that the charge transfer speed of the PtSnCu / CeO2 catalyst is the fastest in the MOR process. Figure 4 Figure 4

[0036] The cyclic voltammetry (CV) curves of the PtSnCu / CeO2 catalyst prepared in Example 1, the PtSnCu / C prepared in Comparative Example 1 and the commercial Pt / C were tested in the same electrolyte at the same temperature, and the obtained cyclic voltammetry (CV) curves are shown in FIG. 4. Continuous CV scanning is a method for evaluating stability, from which it can be seen that the PtSnCu / CeO2 catalyst has the best stability. Figure 5 Figure 5 ​​​​​​​It can be seen that the PtSnCu / CeO2 catalyst prepared in Example 1 has an initial capacity of 1043.5 mA mg Pt -1 , which can be maintained at 695.65 mA mg Pt -1 after 500 cycles, with a capacity retention rate of 66.9 %, while the initial capacities of Pt / C and PtSnCu / C are 665 mA mg Pt -1 , 435.5 mA mg Pt -1 , respectively, and the capacities after 500 cycles are 421 mA mg Pt -1 , 409 mA mg Pt -1, the capacity retention rates were 63.3% and 93.9%, respectively, indicating the ability of CO tolerance and structural stability. It can be seen from the figure that the PtSnCu / CeO2 catalyst prepared in Example 1 has better CO poisoning resistance and electrochemical performance. The PtSnCu / CeO2 catalyst prepared in Example 1 has lower charge transfer resistance and higher methanol oxidation (MOR) activity and higher CO tolerance in an acidic electrolyte. This is because in the methanol oxidation reaction, Sn, Cu and the characteristics of CeO2 jointly optimize the methanol fuel cell catalyst, thereby effectively improving the catalytic activity and CO poisoning resistance of the catalyst. The strong metal-support interaction (SMSI) between PtSnCu alloy and CeO2 effectively adjusts the d-band center of Pt, thereby weakening the adsorption ability of intermediates *CO and *COOH. In addition, when Sn and Cu are added to the Pt catalyst, electrons will transfer from Sn and Cu to Pt. This increases the electron cloud density on the surface of Pt and the d-orbital electron cloud density of Pt atoms. The adsorption of CO molecules on the surface of Pt is achieved by forming a σ bond between the lone pair electrons of the carbon end of CO and the empty d-orbital of Pt, while the d-orbital electrons of Pt are fed back to the anti-bonding π orbital of CO to form a π bond. After the addition of Sn and Cu, the d-orbital electron cloud density of Pt increases, and the number of electrons fed back to the anti-bonding π orbital of CO increases, resulting in a weakening of the C-O bond in the CO molecule and a weakening of the adsorption bond strength between CO and Pt, thereby making CO more easily desorbed from the catalyst surface, improving the stability of the catalyst and reducing the degradation and deactivation of the catalyst during fuel cell operation. CeO2 can provide additional oxygen species through the release and reoxidation of lattice oxygen, promote the oxidation of intermediate products such as CO, and thus improve the CO poisoning resistance of the catalyst. These synergistic mechanisms collectively drive the excellent methanol oxidation performance of PtSnCu / CeO2.

[0037] Example 2: The preparation method of the platinum-based alloy rare earth metal oxide fuel cell anode catalyst of the present embodiment is carried out in the following steps:

[0038] I. Preparation of CeO2 catalyst carrier material by hydrothermal synthesis method:

[0039] (1) 1 g of sodium chloride and 7.2 g of sodium hydroxide were added to 20 mL of distilled water and stirred uniformly to obtain solution A; 0.652 g of cerium nitrate was added to 10 mL of water and stirred uniformly to obtain solution B; then solution B was slowly added to solution A and stirred for 30 min to make the mixture uniform, obtaining a mixed solution;

[0040] (2) The mixed solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal kettle, and the hydrothermal kettle was placed in a forced air drying oven, and hydrothermal reaction was carried out at a temperature of 190 °C for 20 h; after the reaction was completed, the solid phase was separated by centrifugation, and then washed with a 1:1 mixture of water and ethanol three times, and dried in a vacuum drying oven at 60 °C for 12 h to obtain a CeO2 precursor;

[0041] (3) The CeO2 precursor was ground and placed in a porcelain boat, and then the porcelain boat was placed in a tube furnace with argon, and calcined at 400 °C for 6 h, and then cooled to obtain a CeO2 catalyst support material;

[0042] II. 1.335 mL of a chloroplatinic acid solution with a concentration of 0.0192 M, 10 mg of copper chloride, 0.54 mL of stannous chloride with a concentration of 0.021 M, and 20 mg of the CeO2 catalyst support material were added to a round-bottom flask, and then 30 mL of ethylene glycol and 20 mL of ultrapure water were added, and ultrasonic treatment was performed for 1 h to obtain a precursor solution; the precursor solution was placed in an oil bath at 120 °C and oil-bathed for 4 h; the solid phase was separated by centrifugation, and then washed with ethanol three times, and dried in a vacuum drying oven at 60 °C for 12 h to obtain a platinum-based alloy rare earth metal oxide fuel cell catalyst material, which is denoted as PtSnCu / CeO2-400.

[0043] The initial capacity of the platinum-based alloy rare earth metal oxide fuel cell catalyst material PtSnCu / CeO2-400 prepared in this example 2 was 1010.5 mA mg Pt -1 The capacity retention rate was 67.4 %. Pt -1 The capacity retention rate was 67.4 %.

[0044] Example 3: This example is a method for preparing a platinum-based alloy rare earth metal oxide fuel cell anode catalyst, which is carried out according to the following steps:

[0045] I. A CeO2 catalyst support material was prepared by a hydrothermal synthesis method:

[0046] (1) 1 g of sodium chloride and 7.2 g of sodium hydroxide were added to 20 mL of distilled water and stirred uniformly to obtain solution A; 0.652 g of cerium nitrate was added to 10 mL of water and stirred uniformly to obtain solution B; then solution B was slowly added to solution A and stirred for 30 min to obtain a mixed solution;

[0047] (2) The mixed solution was transferred to a 100 mL Teflon-lined autoclave, the autoclave was placed in a blast drying oven, and the hydrothermal reaction was carried out at a temperature of 150 °C for 26 h; after the reaction was completed, the solid phase was centrifuged and separated out, then washed with a 1:1 mixture of water and ethanol three times, and dried in a vacuum drying oven at 60 °C for 12 h to obtain a CeO2 precursor;

[0048] (3) The CeO2 precursor was ground and placed in a porcelain boat, then the porcelain boat was placed in a tube furnace with argon, and calcined at 900 °C for 2 h, and after cooling, a CeO2 catalyst carrier material was obtained;

[0049] II. 1.335 mL of a chloroplatinic acid solution with a concentration of 0.0192 M, 10 mg of copper chloride, 0.54 mL of stannous chloride with a concentration of 0.021 M, and 20 mg of the CeO2 catalyst carrier material were added to a round-bottom flask, then 30 mL of ethylene glycol and 20 mL of ultrapure water were added, and ultrasonic treatment was performed for 1 h to obtain a precursor solution; the precursor solution was placed in an oil bath at 150 °C, and oil bath treatment was performed for 2 h; the solid phase was centrifuged and separated out, then washed with ethanol three times, and dried in a vacuum drying oven at 60 °C for 12 h to obtain a platinum-based alloy rare earth metal oxide fuel cell catalyst material, which was recorded as PtSnCu / CeO2-900.

[0050] The platinum-based alloy rare earth metal oxide fuel cell catalyst material PtSnCu / CeO2-900 prepared in this embodiment 3 was tested by the same method as in embodiment 1, and the initial capacity was 1163.2 mA mg Pt -1 After 500 cycles, the capacity was 820.4 mA mg Pt -1 , and the capacity retention rate was 70.5 %.

Claims

1. A method for preparing a platinum-based alloy rare earth metal oxide methanol fuel cell anode catalyst, characterized in that, This method is performed in the following steps: I. Preparation of CeO2 catalyst support material by hydrothermal synthesis: (1) Add sodium chloride and sodium hydroxide to distilled water and stir until homogeneous to obtain solution A; add cerium nitrate to water and stir until homogeneous to obtain solution B; then add solution B to solution A and stir until homogeneous. A mixture is obtained; (2) The mixture was transferred to a hydrothermal reactor lined with polytetrafluoroethylene. The hydrothermal reactor was placed in a forced-air drying oven and kept at 180 °C for 24 h for hydrothermal reaction. After the reaction was completed, the solid phase was separated by centrifugation, washed and vacuum dried to obtain CeO2 precursor. (3) After grinding the CeO2 precursor, it was placed in a ceramic boat, and then the ceramic boat was placed in a tube furnace with argon gas. The temperature was raised to 600℃ and calcined for 4 h. After cooling, the CeO2 catalyst support material was obtained.

2. The corresponding Pt, Sn, and Cu salt solutions used in the preparation of the PtSnCu alloy were mixed with CeO2 catalyst support material, and then ethylene glycol and distilled water were added. The mixture was ultrasonically stirred to obtain a precursor solution. The precursor solution was placed in an oil bath and heated at 120~160℃ for 1~4 hours. The solid phase was separated by centrifugation, washed, and vacuum dried to obtain a platinum-based alloy rare earth metal oxide methanol fuel cell anode catalyst, denoted as PtSnCu / CeO2. The atomic ratio of Pt, Sn, and Cu in the PtSnCu alloy was 23.02:10.18:66.

80.

2. The method for preparing a platinum-based alloy rare earth metal oxide methanol fuel cell anode catalyst according to claim 1, characterized in that, The vacuum drying described in step one (2) is drying in a vacuum drying oven at a temperature of 60~70 ℃ for 8~12 h.

3. The method for preparing a platinum-based alloy rare earth metal oxide methanol fuel cell anode catalyst according to claim 1 or 2, characterized in that, The oil bath temperature in step two is 140 ℃, and the oil bath time is 2 h.

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