Fuel cell catalyst and its preparation method and application

Abstract

The present invention relates to the technical field of fuel cells and cell catalysts, and discloses a fuel cell catalyst, its preparation method, and its application. The present invention primarily utilizes Bi2Te3 nanosheets as a template and a relatively low-cost platinum precursor to successfully prepare uniformly composed PtBiTe nanosheets under hydrothermal conditions or at room temperature. These nanosheets are then used as fuel cell catalysts for the catalytic oxidation of methanol. The Bi2Te3 nanosheet catalysts prepared in the present invention exhibit superior electrocatalytic activity and stability compared to commercial JM Pt / C catalysts, addressing the current issues of high cost, environmental concerns, and complex operation associated with the synthesis of platinum-based alloy nanosheets.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells and battery catalysts, and in particular relates to a fuel cell catalyst and a preparation method and application thereof. Background Art

[0002] In recent years, hexagonal platinum-based alloy nanosheets have garnered significant attention due to their exceptional electrocatalytic activity. For example, the PtIrBi nanosheets, PtBi / Pt core-shell nanosheets, PtBi nanosheets, PtPb nanosheets, and PtPdM nanosheets, where M = Ni, Fe, or Co, prepared by Professor Guo Shaojun's research group at Peking University, demonstrate excellent activity and stability for the formic acid oxidation, methanol oxidation, ethanol oxidation, polyol oxidation, and oxygen reduction reactions, respectively, relevant to fuel cell applications. For example, the PtPbBi / PtBi core-shell nanosheets, PtPb / Pt-SbOx nanosheets, and PtBiPbNiCo nanosheets prepared by Professor Huang Xiaoqing's research group at Xiamen University demonstrate excellent catalytic activity and stability for formic acid oxidation. For example, the PtRhPb mesoporous nanosheets prepared by Professor Liu Ben's research group at Sichuan University demonstrate excellent catalytic activity and stability for ethanol oxidation. For example, the PtRhBiSnSb nanosheets, PtSnBi nanosheets, Pd-PtBi nanosheets and PtPbBi nanosheets prepared by Professor Quan Zewei's research group at the Southern University of Science and Technology showed excellent catalytic activity in methanol oxidation, ethanol oxidation, glycerol oxidation and formic acid oxidation, respectively.

[0003] However, the current synthesis of platinum-based alloy nanosheets primarily utilizes an expensive platinum precursor, platinum acetylacetonate, and requires the use of oleylamine and octadecene as solvents. Octadecene is toxic and extremely flammable, making the preparation process hazardous. To remove oleylamine, high-speed centrifugation using large amounts of organic reagents such as hexane or cyclohexane is required during product collection, resulting in the generation of significant amounts of organic waste. Furthermore, because oleylamine and octadecene have relatively low melting points of approximately 22°C and 17.5°C, respectively, the centrifugation temperature must be maintained at a minimum of 25°C; otherwise, the two solvents will solidify, rendering centrifugation impossible. Summary of the Invention

[0004] In order to solve the current problems of high synthesis cost, environmental pollution and complicated operation of platinum-based alloy nanosheets, the purpose of the present invention is to provide a fuel cell catalyst and its preparation method and application.

[0005] The present invention synthesizes PtBiTe nanosheets for the first time by adopting a low-cost platinum precursor and a green synthesis method, and uses the nanosheets as fuel cell catalysts for catalyzing methanol oxidation.

[0006] To achieve the above objectives, the technical solutions of the present invention are as follows.

[0007] A first aspect of the present invention provides a method for preparing a fuel cell catalyst, comprising the following steps:

[0008] Using Bi2Te3 nanosheets as a template, a platinum precursor, Bi2Te3 nanosheets, and ethylene glycol were mixed evenly and reacted at 100-220°C to prepare a fuel cell catalyst based on PtBiTe nanosheets.

[0009] Alternatively, using Bi2Te3 nanosheets as a template, Bi2Te3 nanosheets, ascorbic acid, a surfactant, and water are ultrasonically mixed, and then hydrochloric acid and a platinum precursor are added and stirred at room temperature to prepare a fuel cell catalyst of PtBiTe nanosheets;

[0010] The platinum precursor is any one of potassium chloroplatinate, potassium chloroplatinite, chloroplatinic acid, sodium chloroplatinate, and sodium chloroplatinite.

[0011] This invention primarily uses Bi2Te3 nanosheets as a template and a relatively low-cost platinum precursor to successfully prepare uniform PtBiTe nanosheets under hydrothermal conditions or at room temperature. These nanosheets are then used as fuel cell catalysts for methanol oxidation. The Bi2Te3 nanosheets exhibit superior electrocatalytic activity and stability compared to commercial JM Pt / C catalysts, addressing the high cost, environmental concerns, and complex operation of currently synthesized platinum-based alloy nanosheets.

[0012] Preferably, the amount ratio of the platinum precursor, Bi2Te3 nanosheets and ethylene glycol is 48 mg to 49 mg: 11 mg to 12 mg: 30 mL. The ethylene glycol of the present invention functions as a reducing agent and a solvent.

[0013] Preferably, the mass ratio of Bi2Te3 nanosheets, ascorbic acid, surfactant and platinum precursor is 11-12:176-176.5:100:41-42; the usage ratio of Bi2Te3 nanosheets to water and hydrochloric acid is 11mg-12mg:20mL:0.1mL; the surfactant is F127; and the mass percentage of hydrochloric acid is 36%-38%.

[0014] The surfactant of the present invention is F127. Specifically, F127 is Pluronic F127, also known as polyoxyethylene-polyoxypropylene-polyoxyethylene copolymer (PEO-PPO-PEO copolymer). F127 acts as a surfactant to prevent PtBiTe nanosheets from agglomerating.

[0015] Ascorbic acid is a strong reducing agent and is used to reduce K2PtCl4.

[0016] Bi2Te3 nanosheets act as both a template and a reducing agent, and undergo a replacement reaction with K2PtCl4.

[0017] The hydrochloric acid used is concentrated hydrochloric acid, which has the function of weakening the reducing property of ascorbic acid and causing Pt to be reduced slowly.

[0018] Preferably, the preparation method of Bi2Te3 nanosheets is:

[0019] Bi salt, Na2TeO3, polyvinyl pyrrolidone and NaOH ethylene glycol solution are mixed at 120°C, heated to 150°C to 220°C, and subjected to hydrothermal reaction at 150°C to 220°C to prepare Bi2Te3 nanosheets.

[0020] Currently documented methods for preparing platinum-based alloy nanosheets primarily utilize oil bath reflux, and the Bi2Te3 nanosheets are relatively large, ranging from 500 to 1000 nm in size and approximately 14 nm in thickness. Because one of the functions of the Bi2Te3 nanosheets is to serve as a template, their size ultimately influences the size of the resulting PtBiTe nanosheets. Excessively large PtBiTe nanosheets reduce the electrochemically active area of ​​the catalyst, resulting in lower catalytic activity.

[0021] Preferably, the size of the Bi2Te3 nanosheets is 200 nm to 368 nm, and the thickness is about 5 nm.

[0022] Preferably, the Bi salt is Bi(NO3)3·5H2O; in the ethylene glycol solution of NaOH, the concentration of NaOH is 0.1 to 1 mol / L.

[0023] Preferably, the usage ratio of Bi salt, Na2TeO3, polyvinyl pyrrolidone and NaOH ethylene glycol solution is 0.5g-0.6g:0.4g:0.4g:20mL.

[0024] Polyvinyl pyrrolidone is not easily soluble in ethylene glycol and must be heated to dissolve. The purpose of the reaction at 120°C is to dissolve polyvinyl pyrrolidone, bismuth nitrate and sodium tellurite in ethylene glycol, and then carry out a hydrothermal reaction at 150°C to 220°C after forming a solution.

[0025] Preferably, the mixing time at 120° C. is 30 min to 40 min; and the hydrothermal reaction time at 150° C. to 220° C. is 2 h to 10 h.

[0026] The second aspect of the present invention provides a fuel cell catalyst prepared by the preparation method described in the first aspect.

[0027] Preferably, the fuel cell catalyst has a hexagonal flake morphology, a face-centered cubic crystal structure, and a uniform composition; the size of the fuel cell catalyst is 211 nm to 398 nm; and the thickness is about 14.59 nm.

[0028] A second aspect of the present invention provides a use of the fuel cell catalyst described in the second aspect in catalyzing methanol oxidation.

[0029] The oxidation peak of methanol oxidation of the PtBiTe nanosheet catalyst of the present invention is 8.23A / mg Pt , which is much higher than the oxidation peak of methanol oxidation of commercial JMPt / C catalyst, 1.92A / mg Pt This indicates that the methanol oxidation activity of the PtBiTe nanosheet catalyst of the present invention is much higher than that of the commercial JMPt / C catalyst.

[0030] The current density of the PtBiTe nanosheet catalyst of the present invention and the commercial JM Pt / C catalyst is 1.26 A / mg Pt , 0.22A / mg Pt , which shows that the stability of the PtBiTe nanosheet catalyst of the present invention is also very good compared with the commercial JM Pt / C catalyst.

[0031] The above analysis shows that the PtBiTe nanosheet catalyst prepared in the present invention exhibits better electrocatalytic activity and stability than the commercial JM Pt / C catalyst.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. This invention primarily utilizes Bi2Te3 nanosheets as a template and a relatively low-cost platinum precursor to successfully prepare uniform PtBiTe nanosheets under hydrothermal conditions or at room temperature. These nanosheets are then used as fuel cell catalysts for methanol oxidation. The PtBiTe nanosheets exhibit superior electrocatalytic activity and stability compared to commercial JMPt / C catalysts, addressing the high cost, environmental concerns, and complex operation of synthesizing existing platinum-based alloy nanosheets.

[0034] 2. The preparation process of the present invention uses potassium chloroplatinate, which is much cheaper than platinum acetylacetonate, as a platinum precursor. It does not use organic reagents such as oleylamine, which is difficult to remove, or toxic and dangerous reagents such as octadecene. The product can be directly filtered, which is more efficient than high-speed centrifugation. The cleaning process does not require hexane or cyclohexane, only ethanol and ultrapure water. The overall reaction is simple, easy to operate, and more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1This is a scanning electron microscope photograph of the Bi2Te3 hexagonal nanosheets prepared in Example 1.

[0036] Figure 2 This is an X-ray spectrum of the Bi2Te3 hexagonal nanosheets prepared in Example 1. a is a scanning transmission electron microscope image; b is an X-ray spectrum elemental surface scanning composite image; c is a surface scanning image of the Bi element; and d is a surface scanning image of the Te element.

[0037] Figure 3 This is the X-ray diffraction pattern of the Bi2Te3 hexagonal nanosheets prepared in Example 1.

[0038] Figure 4 This is a scanning electron microscope photograph of the PtBiTe nanosheet catalyst prepared in Example 1.

[0039] Figure 5 The scanning transmission electron microscopy images of the PtBiTe nanosheet catalyst prepared in Example 1 are shown in Figures a and b, respectively. Figures c and d are scanning transmission electron microscopy images of the PtBiTe nanosheet catalyst prepared in Example 1.

[0040] Figure 6 This is the X-ray diffraction pattern of the PtBiTe nanosheet catalyst prepared in Example 1.

[0041] Figure 7 This is a scanning electron microscope photograph of the PtBiTe nanosheet catalyst prepared in Example 2.

[0042] Figure 8 This is the total spectrum of the scanning electron microscope energy spectrum of the PtBiTe nanosheet catalyst prepared in Example 2.

[0043] Figure 9 This is a scanning electron microscope photograph of the PtBiTe nanosheet catalyst prepared in Example 3.

[0044] Figure 10 This is the total spectrum of the scanning electron microscope energy spectrum of the PtBiTe nanosheet catalyst prepared in Example 3.

[0045] Figure 11 The following are the CV and CA curves of the PtBiTe nanosheet catalyst prepared in Example 1 and a commercial JM Pt / C catalyst measured in a potassium hydroxide-methanol electrolyte with a potassium hydroxide concentration of 1.0 mol / L and a methanol concentration of 1.0 mol / L. (a) shows the CV curve; b shows the CA curve. The CV curve represents the cyclic voltammetry curve; the CA curve represents the chronoamperometry curve. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the specific implementation of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0047] Unless otherwise specified, the methods described in the embodiments of the present invention are conventional methods. The materials and reagents used are all commercially available unless otherwise specified.

[0048] In the following examples, the NaOH-ethylene glycol solution was prepared by adding 15 g of solid sodium hydroxide to ethylene glycol and then adjusting the volume to 1 L with ethylene glycol to obtain a NaOH-ethylene glycol solution with a sodium hydroxide content of 0.375 mol / L. The NaOH-ethylene glycol solution with a sodium hydroxide content of 0.1 to 1 mol / L was prepared using the above method. The purity of the ethylene glycol was ≥99.5%.

[0049] In the following examples, F127 is specifically Pluronic F127, also known as polyoxyethylene-polyoxypropylene-polyoxyethylene copolymer, abbreviated as PEO-PPO-PEO copolymer. F127 acts as a surfactant to prevent PtBiTe nanosheets from agglomerating.

[0050] In the following embodiments, the mass percentage of concentrated hydrochloric acid is between 36% and 38%, and the mass percentage of concentrated hydrochloric acid used in the following embodiments of the present invention is 37.5%.

[0051] Example 1

[0052] A method for preparing a fuel cell catalyst comprises the following steps:

[0053] Step 1, preparation of Bi2Te3 hexagonal nanosheets:

[0054] 0.5821 g Bi(NO3)3·5H2O, 0.399 g Na2TeO3, 0.4 g polyvinyl pyrrolidone, and 20 mL 0.375 mol / L NaOH-ethylene glycol solution were added to a hydrothermal kettle, stirred for 10 minutes, heated at 120°C for 30 minutes, then stirred for 10 minutes, and then sealed in the hydrothermal kettle and heated at 185°C for 5 hours; filtered, washed with ethanol with a purity of ≥95%, and washed with water; dried in an oven at 60°C or freeze-dried to prepare Bi2Te3 hexagonal nanosheets.

[0055] Step 2, preparation of PtBiTe nanosheet catalyst:

[0056] In a hydrothermal reactor, 11.86mg of Bi2Te3 hexagonal nanosheets and 30mL of ethylene glycol (≥99.5% purity) were added. Ultrasonic dispersion was performed at 300W for 30 minutes to evenly disperse the Bi2Te3 hexagonal nanosheets in the ethylene glycol. This ensures that platinum can grow on the surfaces of the Bi2Te3 hexagonal nanosheets. If the nanosheets are not dispersed, the hexagonal nanosheets will overlap, preventing platinum growth in the covered areas. 48.6mg of K2PtCl6 was then added, stirred for 30 minutes, and the reactor was sealed and heated at 185°C for 5 hours to prepare the PtBiTe nanosheet catalyst, which is used as a fuel cell catalyst.

[0057] Example 2

[0058] A method for preparing a fuel cell catalyst, which differs from Example 1 in that the heating temperature in step 2 is 150° C. The specific preparation method includes the following steps:

[0059] Step 1, preparation of Bi2Te3 hexagonal nanosheets:

[0060] 0.5821 g Bi(NO3)3·5H2O, 0.399 g Na2TeO3, 0.4 g polyvinyl pyrrolidone, and 20 mL 0.375 mol / L NaOH-ethylene glycol solution were added to a hydrothermal kettle, stirred for 10 minutes, heated at 120°C for 30 minutes, then stirred for 10 minutes, and then sealed in the hydrothermal kettle and heated at 185°C for 5 hours; filtered, washed with ethanol with a purity of ≥95%, and washed with water; dried in an oven at 60°C or freeze-dried to prepare Bi2Te3 hexagonal nanosheets.

[0061] Step 2, preparation of PtBiTe nanosheet catalyst:

[0062] In a hydrothermal reactor, 11.86mg of Bi2Te3 hexagonal nanosheets and 30mL of ethylene glycol (≥99.5% purity) were added. Ultrasonic dispersion was performed at 300W for 30 minutes to evenly disperse the Bi2Te3 hexagonal nanosheets in the ethylene glycol. This ensures that platinum can grow on the surfaces of the Bi2Te3 hexagonal nanosheets. If the nanosheets are not dispersed, the hexagonal nanosheets will overlap, preventing platinum growth in the covered areas. 48.6mg of K2PtCl6 was then added, stirred for 30 minutes, and the reactor was sealed and heated at 150°C for 5 hours to prepare the PtBiTe nanosheet catalyst, which is used as a fuel cell catalyst.

[0063] Example 3

[0064] A method for preparing a fuel cell catalyst, which differs from Example 1 in that step 2 adopts a room temperature method. The specific preparation method includes the following steps:

[0065] Step 1, preparation of Bi2Te3 hexagonal nanosheets:

[0066] 0.5821 g Bi(NO3)3·5H2O, 0.399 g Na2TeO3, 0.4 g polyvinyl pyrrolidone, and 20 mL 0.375 mol / L NaOH-ethylene glycol solution were added to a hydrothermal kettle, stirred for 10 minutes, heated at 120°C for 30 minutes, then stirred for 10 minutes, and then sealed in the hydrothermal kettle and heated at 185°C for 5 hours; filtered, washed with ethanol with a purity of ≥95%, and washed with water; dried in an oven at 60°C or freeze-dried to prepare Bi2Te3 hexagonal nanosheets.

[0067] Step 2, preparation of PtBiTe nanosheet catalyst:

[0068] In a beaker, add 11.86 mg Bi2Te3 hexagonal nanosheets, 176.2 mg ascorbic acid, 100 mg F127 and 20 mL ultrapure water. After ultrasonic mixing, add 0.1 mL concentrated hydrochloric acid and stir for 1 to 5 minutes. Then, add 41.5 mg K2PtCl4 and stir for another 2 hours.

[0069] The mixture is then centrifuged at 10,000 rpm for 10 minutes and washed with water five times; alternatively, vacuum filtration is performed and the mixture is washed with water five times; and freeze-dried at a temperature of about 0° C. for 48 hours to obtain a PtBiTe nanosheet catalyst, which is a fuel cell catalyst.

[0070] Example 4

[0071] A method for preparing a fuel cell catalyst, which differs from Example 1 in that the content of sodium hydroxide in the NaOH-ethylene glycol solution is 0.1 mol / L. The specific method comprises the following steps:

[0072] Step 1, preparation of Bi2Te3 hexagonal nanosheets:

[0073] 0.5821 g Bi(NO3)3·5H2O, 0.399 g Na2TeO3, 0.4 g polyvinyl pyrrolidone, and 20 mL 0.1 mol / L NaOH-ethylene glycol solution were added to a hydrothermal kettle, stirred for 10 min, heated at 120°C for 30 min, then stirred for 10 min, and then sealed in the hydrothermal kettle and heated at 185°C for 5 h; filtered, washed with ethanol with a purity of ≥95%, and washed with water; dried in an oven at 60°C or freeze-dried to prepare Bi2Te3 hexagonal nanosheets.

[0074] Step 2, preparation of PtBiTe nanosheet catalyst:

[0075] In a hydrothermal reactor, 11.86mg of Bi2Te3 hexagonal nanosheets and 30mL of ethylene glycol (≥99.5% purity) were added. Ultrasonic dispersion was performed at 300W for 30 minutes to evenly disperse the Bi2Te3 hexagonal nanosheets in the ethylene glycol. This ensures that platinum can grow on the surfaces of the Bi2Te3 hexagonal nanosheets. If the nanosheets are not dispersed, the hexagonal nanosheets will overlap, preventing platinum growth in the covered areas. 48.6mg of K2PtCl6 was then added, stirred for 30 minutes, and the reactor was sealed and heated at 185°C for 5 hours to prepare the PtBiTe nanosheet catalyst, which is used as a fuel cell catalyst.

[0076] Example 5

[0077] A method for preparing a fuel cell catalyst, which differs from Example 1 in that the content of sodium hydroxide in the NaOH-ethylene glycol solution is 1 mol / L. The specific method comprises the following steps:

[0078] Step 1, preparation of Bi2Te3 hexagonal nanosheets:

[0079] 0.5821 g Bi(NO3)3·5H2O, 0.399 g Na2TeO3, 0.4 g polyvinyl pyrrolidone, and 20 mL 1 mol / L NaOH-ethylene glycol solution were added to a hydrothermal kettle, stirred for 10 min, heated at 120°C for 30 min, then stirred for 10 min, and then sealed in the hydrothermal kettle and heated at 185°C for 5 h; filtered, washed with ethanol with a purity of ≥95%, and washed with water; dried in an oven at 60°C or freeze-dried to prepare Bi2Te3 hexagonal nanosheets.

[0080] Step 2, preparation of PtBiTe nanosheet catalyst:

[0081] In a hydrothermal reactor, 11.86mg of Bi2Te3 hexagonal nanosheets and 30mL of ethylene glycol (≥99.5% purity) were added. Ultrasonic dispersion was performed at 300W for 30 minutes to evenly disperse the Bi2Te3 hexagonal nanosheets in the ethylene glycol. This ensures that platinum can grow on the surfaces of the Bi2Te3 hexagonal nanosheets. If the nanosheets are not dispersed, the hexagonal nanosheets will overlap, preventing platinum growth in the covered areas. 48.6mg of K2PtCl6 was then added, stirred for 30 minutes, and the reactor was sealed and heated at 185°C for 5 hours to prepare the PtBiTe nanosheet catalyst, which is used as a fuel cell catalyst.

[0082] The fuel cell catalyst prepared in the above example was subjected to relevant performance analysis such as scanning electron microscopy analysis, X-ray energy spectrum analysis, and X-ray diffraction analysis, and its performance was compared with that of a commercial JMPt / C catalyst.

[0083] Test 1: Scanning electron microscopy analysis of Bi2Te3 hexagonal nanosheets.

[0084] The Bi2Te3 hexagonal nanosheets prepared in Example 1 were analyzed by scanning electron microscopy. Figure 1 . Figure 1 This is a scanning electron microscope photograph of the Bi2Te3 hexagonal nanosheets prepared in Example 1.

[0085] Depend on Figure 1 It can be seen that the Bi2Te3 hexagonal nanosheets prepared in Example 1 have a hexagonal shape, are very thin, and are translucent. Figure 1 The thickness of the moderately warped flakes was measured to be approximately 5 nm, and their width ranged from 200 nm to 368 nm. The width here is the distance between the two parallel sides of the hexagonal shape.

[0086] Test 2: X-ray energy dispersive spectroscopy analysis of Bi2Te3 hexagonal nanosheets.

[0087] The Bi2Te3 hexagonal nanosheets prepared in Example 1 were subjected to X-ray energy spectrum analysis, and the results are shown in FIG. Figure 2 . Figure 2 This is an X-ray spectrum of the Bi2Te3 hexagonal nanosheets prepared in Example 1. a is a scanning transmission electron microscope image; b is an X-ray spectrum elemental surface scanning composite image; c is a surface scanning image of the Bi element; and d is a surface scanning image of the Te element.

[0088] Depend on Figure 2 It can be seen that Bi and Te elements are evenly dispersed on the nanosheets. Figure 2 Figure a further confirms that the Bi2Te3 hexagonal nanosheets prepared in Example 1 have a hexagonal sheet morphology. Figure 2 As can be seen from Figures b to d, Bi and Te elements are uniformly dispersed on the nanosheets, and through measurement, it is found that the atomic percentages of Bi and Te are 43.72% and 56.28%, respectively, and the atomic ratio of Bi and Te is very close to 2:3.

[0089] Test 3: X-ray diffraction analysis of Bi2Te3 hexagonal nanosheets.

[0090] The Bi2Te3 hexagonal nanosheets prepared in Example 1 were subjected to X-ray diffraction analysis. Figure 3 . Figure 3 This is the X-ray diffraction pattern of the Bi2Te3 hexagonal nanosheets prepared in Example 1.

[0091] Depend on Figure 3It shows that the X-ray diffraction pattern of the Bi2Te3 hexagonal nanosheets prepared in Example 1 is consistent with the diffraction pattern of standard Bi2Te3, corresponding to Bi2Te3 with a hexagonal crystal structure, JCPDS No.18-0863.

[0092] The above characterization data show that Example 1 of the present invention successfully prepared Bi2Te3 hexagonal nanosheets.

[0093] Test 4: Scanning electron microscopy analysis of PtBiTe nanosheet catalyst.

[0094] The PtBiTe nanosheet catalyst prepared in Example 1 was analyzed by scanning electron microscopy. Figure 4 . Figure 4 This is a scanning electron microscope photograph of the PtBiTe nanosheet catalyst prepared in Example 1.

[0095] Depend on Figure 4 It can be seen that the PtBiTe nanosheet catalyst prepared in Example 1 retains the hexagonal sheet morphology of the template Bi2Te3 hexagonal nanosheet, and also presents a hexagonal sheet morphology, with a surface size of 211nm to 398nm and a thickness of about 14.59nm.

[0096] The PtBiTe nanosheet catalyst prepared in Example 2 was analyzed by scanning electron microscopy. Figure 7 . Figure 7 This is a scanning electron microscope photograph of the PtBiTe nanosheet catalyst prepared in Example 2.

[0097] Depend on Figure 7 It can be seen that the PtBiTe nanosheet catalyst prepared in Example 2 retains the hexagonal sheet morphology of the template Bi2Te3 hexagonal nanosheet and also presents a hexagonal sheet structure.

[0098] The PtBiTe nanosheet catalyst prepared in Example 3 was analyzed by scanning electron microscopy. Figure 9 . Figure 9 This is a scanning electron microscope photograph of the PtBiTe nanosheet catalyst prepared in Example 3.

[0099] Depend on Figure 9 It can be seen that the PtBiTe nanosheet catalyst prepared in Example 3 retains the hexagonal morphology of the Bi2Te3 hexagonal nanosheet template and also exhibits a hexagonal sheet structure. However, compared to the PtBiTe nanosheet catalysts prepared under hydrothermal conditions in Examples 1 and 2, the surface of the PtBiTe nanosheet catalyst prepared in Example 3 is relatively rougher.

[0100] Scanning electron microscopy analysis of the PtBiTe nanosheet catalysts prepared in Example 4 and Example 5 showed that the PtBiTe nanosheet catalysts prepared in Example 4 and Example 5 also exhibited a hexagonal sheet structure, which was similar to the surface morphology of the PtBiTe nanosheet catalyst prepared in Example 1.

[0101] Test 5: Scanning transmission electron microscopy analysis of PtBiTe nanosheet catalysts.

[0102] The PtBiTe nanosheet catalyst prepared in Example 1 was analyzed by scanning transmission electron microscopy. Figure 5 . Figure 5 The scanning transmission electron microscopy images of the PtBiTe nanosheet catalyst prepared in Example 1 are shown in Figures a and b, respectively. Figures c and d are scanning transmission electron microscopy images of the PtBiTe nanosheet catalyst prepared in Example 1.

[0103] Depend on Figure 5 The results show that the three elements Pt, Bi and Te are evenly distributed on the nanosheets.

[0104] The PtBiTe nanosheet catalyst prepared in Example 2 was subjected to scanning electron microscope energy spectrum analysis. Figure 8 . Figure 8 This is the total spectrum of the scanning electron microscope energy spectrum of the PtBiTe nanosheet catalyst prepared in Example 2.

[0105] Depend on Figure 8 It can be confirmed that the components of the PtBiTe nanosheet catalyst prepared in Example 2 are Pt, Bi, and Te.

[0106] The PtBiTe nanosheet catalyst prepared in Example 3 was subjected to scanning electron microscope energy spectrum analysis. Figure 10 . Figure 10 This is the total spectrum of the scanning electron microscope energy spectrum of the PtBiTe nanosheet catalyst prepared in Example 3.

[0107] Depend on Figure 10 It can be confirmed that the components of the PtBiTe nanosheet catalyst prepared in Example 3 are Pt, Bi, and Te.

[0108] Test 6: X-ray diffraction analysis of PtBiTe nanosheet catalyst.

[0109] The PtBiTe nanosheet catalyst prepared in Example 1 was subjected to X-ray diffraction analysis, and the results are shown in FIG. Figure 6 . Figure 6 This is the X-ray diffraction pattern of the PtBiTe nanosheet catalyst prepared in Example 1.

[0110] Depend on Figure 6It can be seen that compared with the standard PDF card JCPDS No.04-0802 of Pt, the PtBiTe nanosheet catalyst prepared in Example 1 of the present invention has a face-centered cubic crystal structure with uniform composition; rather than the hexagonal structure of the template Bi2Te3 hexagonal nanosheet. Moreover, the diffraction peak of the PtBiTe nanosheet catalyst prepared in Example 1 on the X-ray diffraction spectrum has made a slight shift to a higher angle compared to the diffraction peak of pure Pt, indicating the formation of a platinum-based alloy. Figure 5 The data indicate that the PtBiTe nanosheet catalyst prepared in Example 1 does not have a core-shell structure like the Bi2Te3 hexagonal nanosheets-Pt structure, but rather a uniform structure inside and out. During the preparation of the PtBiTe nanosheet catalyst in Example 1, the majority of the platinum precursor was reduced by ethylene glycol, with only a small amount of the platinum precursor undergoing a substitution reaction with Bi and Te atoms. Furthermore, due to interdiffusion between the elements, a uniform structure was ultimately formed.

[0111] The PtBiTe nanosheet catalysts prepared in Examples 2 to 5 were tested by X-ray diffractometer. Figure 6 The results are similar, both showing a face-centered cubic structure, and the internal and external components of the overall structure are uniform.

[0112] Test 7: Application of PtBiTe nanosheet catalyst as fuel cell catalyst for catalytic methanol oxidation.

[0113] The experimental example of catalyzing methanol oxidation using the PtBiTe nanosheet catalyst prepared in Example 1 as a fuel cell catalyst was used as an experimental group; the experimental example of catalyzing methanol oxidation using the commercial JM Pt / C catalyst as a fuel cell catalyst was used as a control group. The activity and stability of the catalytic methanol oxidation were tested respectively. The results are as follows: Figure 11 The commercial JM Pt / C catalyst was purchased from Johnson Matthey Company, with a Pt content of 20% by weight. The full English name of JM Pt / C is Johnson Matthey Pt / C. The Chinese name of Johnson Matthey Company is Zhuang Xin Wan Feng.

[0114] The specific test methods are as follows:

[0115] The electrolyte is prepared by uniformly mixing potassium hydroxide, methanol and water, and then adding water to make the volume 1 L to obtain a potassium hydroxide-methanol electrolyte with a potassium hydroxide concentration of 1.0 mol / L and a methanol concentration of 1.0 mol / L.

[0116] Electrochemical activity is typically tested using cyclic voltammetry. The specific test method involves a three-electrode system with a mercury / mercuric oxide electrode as the reference electrode, a platinum wire as the counter electrode, and a glassy carbon electrode coated with a catalyst slurry as the working electrode. A 1.0 mol / L potassium hydroxide-methanol electrolyte is used as the alkaline electrolyte.

[0117] The testing method of the embodiment of the present invention is to mix an appropriate amount of the fuel cell catalyst to be tested with 2.7 mL of anhydrous ethanol and 0.3 mL of Nafion solution in a 10 mL glass bottle, and then use an ultrasonic cell crusher to ultrasonically disperse the catalyst to uniformly disperse it. Then, take 10 μL and drop it onto the surface of a clean glassy carbon electrode, dry it naturally, and obtain a working electrode (the mass of platinum on the glassy carbon electrode is 0.002 mg. The mass of the catalyst added to the glass bottle during dispersion is determined based on this requirement).

[0118] Before the test, high-purity nitrogen was passed for 15 minutes to remove oxygen from the solution. The scanning range was 0.05 to 1 V (relative to the reversible hydrogen electrode RHE) and the scanning rate was 50 mV / s.

[0119] Figure 11 The following are the CV and CA curves of the PtBiTe nanosheet catalyst prepared in Example 1 and the commercial JMPt / C catalyst measured in a potassium hydroxide-methanol electrolyte with a potassium hydroxide concentration of 1.0 mol / L and a methanol concentration of 1.0 mol / L. (a) shows the CV curve; b shows the CA curve. The CV curve represents the cyclic voltammetry curve; the CA curve represents the chronoamperometry curve.

[0120] Depend on Figure 11 As can be seen from Figure a, the oxidation peak of methanol oxidation of the PtBiTe nanosheet catalyst of Example 1 is 8.23 ​​A / mg Pt , which is much higher than the oxidation peak of methanol oxidation of commercial JM Pt / C catalyst, 1.92 A / mg Pt This indicates that the methanol oxidation activity of the PtBiTe nanosheet catalyst of Example 1 is much higher than that of the commercial JM Pt / C catalyst.

[0121] from Figure 11 As can be seen from Figure b, throughout the entire test process, the current density of the PtBiTe nanosheet catalyst of Example 1 is higher than that of the commercial JM Pt / C catalyst, which once again shows that the PtBiTe nanosheet catalyst of Example 1 has a higher catalytic activity. In addition, at the end of the test, that is, at 3600s, the current density of the PtBiTe nanosheet catalyst of Example 1 and the commercial JM Pt / C catalyst are 1.26A / mg, respectively. Pt , 0.22A / mg Pt, which shows that compared with the commercial JMPt / C catalyst, the stability of the PtBiTe nanosheet catalyst in Example 1 is also very good.

[0122] The PtBiTe nanosheet catalysts prepared in Examples 2 to 5 were tested for their catalytic methanol oxidation activity and stability. The results showed that the PtBiTe nanosheet catalysts prepared in Examples 2, 3, 4 and 5 also exhibited excellent catalytic methanol oxidation activity and good stability.

[0123] The above are only preferred embodiments of the present invention and are 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 in the scope of protection of the present invention.

Claims

1. A method for preparing a fuel cell catalyst, characterized in that: The following steps are involved: Using Bi2Te3 nanosheets as a template, a platinum precursor, Bi2Te3 nanosheets, and ethylene glycol were mixed uniformly and reacted at 100-220°C. The ethylene glycol reduced the platinum precursor, and interdiffusion occurred between the elements, forming a uniform structure. A fuel cell catalyst with a hexagonal morphology of PtBiTe nanosheets was prepared. Alternatively, using Bi2Te3 nanosheets as a template, Bi2Te3 nanosheets, ascorbic acid, a surfactant, and water are ultrasonically mixed, and then hydrochloric acid and a platinum precursor are added and stirred at room temperature to prepare a fuel cell catalyst of PtBiTe nanosheets with a hexagonal sheet morphology; The surfactant is F127; the mass percentage of hydrochloric acid is 36% to 38%; The Bi2Te3 nanosheets have a hexagonal sheet morphology; the platinum precursor is any one of potassium chloroplatinate, potassium chloroplatinite, chloroplatinic acid, sodium chloroplatinate, and sodium chloroplatinite; The dosage ratio of platinum precursor, Bi2Te3 nanosheets and ethylene glycol is 48mg~49mg:11mg~12mg:30mL; The mass ratio of Bi2Te3 nanosheets, ascorbic acid, surfactant and platinum precursor is 11-12:176-176.5:100:41-42; The usage ratio of Bi2Te3 nanosheets to water and hydrochloric acid is 11 mg-12 mg: 20 mL: 0.1 mL.

2. The method for preparing a fuel cell catalyst according to claim 1, wherein: The preparation method of Bi2Te3 nanosheets is: Bi salt, Na2TeO3, polyvinyl pyrrolidone and NaOH ethylene glycol solution are mixed at 120°C, heated to 150°C to 220°C, and subjected to hydrothermal reaction at 150°C to 220°C to prepare Bi2Te3 nanosheets.

3. The method for preparing a fuel cell catalyst according to claim 2, wherein: The Bi salt is Bi(NO3)3·5H2O; In the ethylene glycol solution of NaOH, the concentration of NaOH is 0.1 to 1 mol / L.

4. The method for preparing a fuel cell catalyst according to claim 2, wherein: The dosage ratio of Bi salt, Na2TeO3, polyvinyl pyrrolidone and NaOH ethylene glycol solution is 0.5g~0.6g:0.4g:0.4g:20mL.

5. The method for preparing a fuel cell catalyst according to claim 2, wherein: The mixing time at 120° C. is 30 to 40 minutes; the hydrothermal reaction time at 150 to 220° C. is 2 to 10 hours.

6. A fuel cell catalyst, characterized in that The compound is prepared by the preparation method according to any one of claims 1 to 5.

7. The fuel cell catalyst according to claim 6, characterized in that The fuel cell catalyst has a hexagonal flake morphology, a face-centered cubic crystal structure, and uniform composition; and the size of the fuel cell catalyst is 211 nm to 398 nm.

8. Use of the fuel cell catalyst according to claim 6 in catalyzing methanol oxidation.

Images