A method for synthesizing a pt-based nano-high-entropy alloy on a carrier

Abstract

The application discloses a method for synthesizing a Pt-based nano high-entropy alloy on a carrier, wherein precursor platinum salt, precursor bismuth salt, precursor cobalt salt, precursor copper salt and precursor nickel salt are dissolved in a mixed solution of DMF and acetonitrile to obtain a precursor solution; the precursor solution is stirred to be completely dissolved; an electrochemical deposition is performed by adopting a three-electrode system, a saturated mercury electrode is used as a reference electrode, a platinum mesh electrode is used as a counter electrode, and a clamped sheet electrode is used as a working electrode; carbon cloth is pretreated to remove impurities on the surface, the carbon cloth is respectively subjected to ultrasonic treatment in a acetone solution and deionized water for 30 min, and is dried at room temperature; the treated carbon cloth is clamped on the clamped sheet electrode, and a 1*1 cm part is reserved as a carrier of the nano high-entropy alloy; the electrode is immersed in the precursor solution, only the 1*1 cm part of the carbon cloth of the working electrode is immersed in the precursor solution, the range of a constant potential is between-0.4 V and-0.5 V, and the deposition time is 1200-1800 s, so that a platinum-based high-entropy alloy loaded on the carbon cloth is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new energy materials, and particularly relates to a method for synthesizing a Pt-based nano high-entropy alloy on a carrier. BACKGROUND

[0002] In recent years, direct methanol fuel cells (DMFCs) have been closely followed by researchers due to their high energy density, high energy conversion efficiency, easy storage and transportation of methanol, and many other advantages, and DMFCs have very broad application potential and development prospects. Pt becomes the key material of the anode catalytic layer of DMFCs because it can promote the activation of C-H bonds. However, the main active substance of Pt as a fuel cell catalyst has a low reserve in the earth's crust, which greatly increases the cost of DMFCs. Pt is easily poisoned by the toxic intermediate (CO) produced in the methanol oxidation reaction and thus loses the electrocatalytic activity. Therefore, a material with effective resistance to CO in the methanol oxidation process is designed, and the oxidation mechanism of CO on the surface of the material is studied. The surface electron structure and crystal structure of the material are optimized by alloying, so that a large number of Pt active sites are obtained on the surface of the material, and the electrocatalytic activity of the material is enhanced. In the process of electrocatalysis, a large amount of oxygen-containing adsorbates (OH ad ) are enriched on the surface of the material, which accelerates the removal of CO produced in the methanol oxidation process. The stability of the material can be enhanced by loading the Pt1Bi2Co1Cu1Ni1 high-entropy alloy on the carbon cloth. Due to the high conductivity of the carbon cloth, the electron transfer is more active. However, the reaction path of methanol oxidation cannot be precisely controlled at present, so the performance of the catalyst in the working process is inevitably reduced; the incomplete electron transfer leads to a decrease in the utilization rate of methanol, so that the DMFCs cannot reach the theoretical capacity. SUMMARY

[0003] The technical problem solved by the application is that the Pt catalyst is expensive and is easily deactivated by the intermediate product (especially CO) in the methanol oxidation process.

[0004] The application solves the technical problems of the prior art, provides a method for synthesizing a Pt-based nano high-entropy alloy on a carrier, improves the coordination environment of Pt atoms on the electronic structure, reduces the d-band center of the material, promotes the removal of CO on the surface of the material, and thus improves the resistance of the catalyst to CO and the stability of the material. Based on the electrochemical reduction of the Pt-based alloy nanomaterial, the sample can be easily taken out for characterization during the synthesis process, and the growth process of the Pt1Bi2Co1Cu1Ni1 high-entropy alloy can be easily explored.

[0005] Technical scheme

[0006] To achieve the above object, the application is implemented by the following technical scheme:

[0007] A method for synthesizing a Pt-based nano high-entropy alloy on a carrier, specifically comprising the following steps:

[0008] Step 1: Dissolve 0.05 mmol / L of precursor bismuth salt in a mixed solution of DMF and acetonitrile, stir for 5-10 min to dissolve, and obtain precursor solution A with a stirring speed of 500 r / min.

[0009] Step 2: Dissolve precursor platinum salt, precursor cobalt salt, precursor copper salt, and precursor nickel salt in solution A according to a molar ratio of 1:1:1:1, obtain solution B, and stir, control the stirring speed at 500 r / min, and control the stirring time at 10-20 min.

[0010] Step 3: Soak a piece of carbon cloth in acetone solution and deionized water for ultrasonic treatment for 30 min, then air dry at room temperature, and clamp it on a clamping electrode, leaving an area of 1*1 cm, and immerse a three-electrode system composed of a saturated calomel electrode as a reference electrode, a platinum mesh electrode as a counter electrode, and a clamping electrode as a working electrode in solution B.

[0011] Step 4: Set the program of the Kost CS350M electrochemical workstation to chronoamperometry test, set the constant potential to -0.45V to -0.5V, and set the time to 1200s-1800s.

[0012] Step 5: Take out the carbon cloth after electrodeposition, rinse with deionized water, and vacuum dry at 60℃ for 1h.

[0013] Further, in the precursor solution B, the concentrations of platinum ions, cobalt ions, copper ions, and nickel ions are 0.025 mmol / L, the preset molar ratio of the precursor platinum salt and the precursor bismuth salt is 1:2, and the volume ratio of DMF and acetonitrile in solution A is 4:1-3.

[0014] Further, in the second step, the molar ratio of the precursor platinum ions, bismuth ions, cobalt ions, copper ions, and nickel ions is 1:2:1:1.

[0015] 2:1:1:1, dissolved in solution A.

[0016] Further, the precursor platinum salt is chloroplatinic acid and / or potassium chloroplatinate; the precursor bismuth salt is bismuth nitrate; the precursor cobalt salt is cobalt chloride; the precursor copper salt is copper chloride; and the precursor nickel salt is nickel chloride.

[0017] Further, the electrodeposition temperature of the Kost CS350M electrochemical workstation is room temperature.

[0018] Original explanation: the metal ions in the plating solution are brought to the reduction potential by voltage, and the reduction voltage is adjusted to the appropriate range, so that the reduction of platinum, bismuth, cobalt, copper and nickel occurs at the same time. In the initial stage of electrodeposition, crystal nuclei will grow on the carbon cloth, and with the passage of time, the crystals will slowly grow and form stable high-entropy alloys. By continuous adjustment, at a potential of-0.45V to-0.5V, the five metals are more likely to be co-reduced.

[0019] Beneficial effects:

[0020] The application provides a method for synthesizing a Pt-based nano high-entropy alloy on a carrier, which has the following advantages compared with the prior art

[0021] Beneficial effects:

[0022] 1. The alloy prepared by the method is composed of Pt, Bi, Co, Cu and Ni elements;

[0023] 2. The Pt1Bi2Co1Cu1Ni1 / CC composite material prepared by the method improves the coordination environment of Pt atoms in structure and adjusts the surface to have a large number of defects, so that more active sites are formed;

[0024] 3. Based on the change of the catalytic environment space, the selectivity and kinetics of the electrochemical reaction are affected, the structure-activity relationship between the Pt-based alloy and MOR is revealed, and the synthesis of a new type of high-efficiency Pt-based alloy catalyst is further guided;

[0025] 4. In the experimental test process, the mass activity of the Pt1Bi2Co1Cu1Ni1 / CC composite material is 5.02Amg measured by cyclic voltammetry in a 0.5M H2SO4+0.5M CH3OH electrolyte solution -1 , which is 3.3 times the result of 1.52Amg measured by Pt / CC -1 ; the remaining activity of the Pt-based alloy after five stability tests is 4.5Amg measured by chronocoulometry in a 0.5M H2SO4+0.5M CH3OH electrolyte solution -1 , which is much higher than that of Pt / CC (tending to 0); therefore, it can be seen that the Pt-based alloy prepared by us has high activity and stability. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a scanning electron microscope image of the Pt1Bi2Co1Cu1Ni1 / CC composite material obtained in Example 1 of the application, wherein the thumbnail in the upper right corner is the structure and morphology of the Pt1Bi2Co1Cu1Ni1 / CC composite material under low magnification;

[0027] Figure 2is the transmission electron microscope image of the Pt1Bi2Co1Cu1Ni1 / CC composite material obtained in Example 1 of the present application; wherein a is the morphology structure picture under the transmission electron microscope, and the rest are the corresponding element energy spectrum pictures;

[0028] Figure 3 is the X-ray photoelectron spectrum of the Pt1Bi2Co1Cu1Ni1 / CC composite material obtained in Example 1 of the present application;

[0029] Figure 4 is the cyclic voltammogram of the catalytic activity of the Pt1Bi2Co1Cu1Ni1 / CC composite material and the Pt / CC catalyst prepared under the same conditions in the acid methanol oxidation reaction, wherein the red line represents the cyclic voltammogram of the catalytic activity of the methanol oxidation reaction of the Pt1Bi2Co1Cu1Ni1 / CC composite material, and the black line represents the cyclic voltammogram of the catalytic activity of the methanol oxidation reaction of the Pt / CC catalyst;

[0030] Figure 5 is the chronoamperogram of the catalytic activity of the Pt1Bi2Co1Cu1Ni1 / CC composite material and the Pt / CC catalyst in the acid methanol oxidation reaction, wherein the red line is the chronoamperogram of the catalytic activity of the methanol oxidation reaction of the Pt1Bi2Co1Cu1Ni1 / CC, and the black line is the chronoamperogram of the catalytic activity of the methanol oxidation reaction of the Pt / CC catalyst. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0032] Example 1

[0033] A method for synthesizing a Pt-based nano-high-entropy alloy on a carrier, specifically comprising the following steps:

[0034] First step: in a 50 mL flask, dissolve 0.05 mmol / L of bismuth nitrate as a precursor bismuth salt in a mixed solution of DMF and acetonitrile, stir for 5-10 min to dissolve, and obtain precursor solution A, wherein the volume ratio of DMF to acetonitrile in solution A is 4:1, and the stirring speed is 500 r / min;

[0035] Second step: the precursor platinum salt, the precursor cobalt salt, the precursor copper salt and the precursor nickel salt are dissolved in solution A according to the molar ratio of 1:1:1:1, to obtain solution B and stirring, control the stirring speed of 500r / min, the stirring time is controlled in 10min, the molar ratio of the precursor platinum ion, bismuth ion, cobalt ion, copper ion and nickel ion is 1:2:1:1:1, dissolved in solution A, the precursor platinum salt is chloroplatinic acid and / or potassium chloroplatinite; the precursor bismuth salt is bismuth nitrate; the precursor cobalt salt is cobalt chloride; the precursor copper salt is copper chloride; the precursor nickel salt is nickel chloride;

[0036] Third step: a piece of carbon cloth is immersed in acetone solution and deionized water in turn and ultrasonic treated for 30min, then dried at room temperature, and clamped on the clamping electrode, reserving an area of 1*1cm, a saturated calomel electrode as a reference electrode, a platinum mesh electrode as a counter electrode and a clamping electrode as a working electrode to form a three-electrode system immersed in solution B;

[0037] Fourth step: the program of the Kost CS350M electrochemical workstation is set to chronoamperometry test, the constant potential is set to-0.45V,

[0038] The time is set to 1200s;

[0039] Fifth step: the carbon cloth after electrodeposition is taken out and washed with deionized water, vacuum dried at 60℃ for 1h, to obtain the Pt1Bi2Co1Cu1Ni1 / CC composite material.

[0040] The Pt1Bi2Co1Cu1Ni1 / CC composite material obtained above is observed by scanning electron microscope (SEM), as shown in Figure 1 The morphology of the obtained Pt1Bi2Co1Cu1Ni1 / CC composite material is a large number of nanoscale flakes, in which metal particles are loaded inside. At the same time, as shown in Figure 2 The transmission electron microscope shows that the Pt1Bi2Co1Cu1Ni1 / CC composite material is a flexible flake structure, in which a is a morphology diagram and b is an energy spectrum diagram of the corresponding element;

[0041] The Pt1Bi2Co1Cu1Ni1 / CC composite material obtained above is detected by X-ray photoelectron spectroscopy, and from the total spectrum of XPS, it can be seen that the five elements of Pt, Bi, Co, Cu and Ni are reduced, which proves the successful synthesis of the Pt1Bi2Co1Cu1Ni1 high-entropy alloy.

[0042] Methanol oxidation reaction (MOR) catalytic activity test:

[0043] (1) Preparation of catalytic electrode

[0044] The Pt1Bi2Co1Cu1Ni1 / CC composite prepared above was sandwiched between the gauze electrodes, and the deposited part was fully exposed outside,

[0045] The part without deposition was sandwiched between the gauze electrodes.

[0046] (2) MOR test

[0047] The MOR test was performed in 0.5 mol / L H2SO4+0.5 mol / L CH3OH saturated with Ar at a scanning rate of 50 mV / s. The long-term stability of the prepared sample was determined by chronoamperometry in 0.5 mol / L H2SO4 solution containing 0.5 mol / L CH3OH at 0.66 V (vs. saturated calomel electrode, SCE).

[0048] The MOR performance of the Pt1Bi2Co1Cu1Ni1 / CC composite obtained in Example 1 was tested by using a CTS workstation in a three-electrode cell system. In the three-electrode system, a saturated calomel electrode and a Pt mesh were used as the reference electrode and the counter electrode, respectively.

[0049] Figure 4 The cyclic voltammogram of the Pt1Bi2Co1Cu1Ni1 / CC composite of Example 1 in 0.5 mol / L H2SO4 solution containing 0.5 mol / L CH3OH was obtained at a potential range of -0.2 V to 1 V (vs. saturated calomel electrode, SCE) and a scanning rate of 50 mV / s. In the figure, the red line represents the cyclic voltammogram of the methanol oxidation reaction catalytic activity of the Pt1Bi2Co1Cu1Ni1 / CC composite, and the black line represents the cyclic voltammogram of the methanol oxidation reaction catalytic activity of the commercial Pt / C catalyst; from Figure 4 It can be seen that the MOR activity of the Pt1Bi2Co1Cu1Ni1 / CC composite is 5.02 A mg -1 , while the activity of Pt / CC is only 1.52 A mg -1 .

[0050] Figure 5 The potential change of the Pt1Bi2Co1Cu1Ni1 / CC composite of Example 1 in 0.5 mol / L H2SO4 solution containing 0.5 mol / L CH3OH at a potential of 0.66 V (vs. saturated calomel electrode, SCE) after 3600 s is shown in the figure, in which the red line represents the current curve of the methanol oxidation reaction catalytic activity of the Pt1Bi2Co1Cu1Ni1 / CC composite, and the black line represents the current curve of the methanol oxidation reaction catalytic activity of the Pt / CC catalyst; from Figure 5It can be concluded that after 5 stability tests, the activity of the Pt1Bi2Co1Cu1Ni1 / CC composite material remained at 4.5 A mg. -1 In contrast, Pt / CC showed near-zero activity after five stability tests, meaning it lost its activity.

[0051] Example 2

[0052] A method for synthesizing Pt-based nano-high-entropy alloys on a support specifically includes the following steps:

[0053] Step 1: In a 50 mL flask, dissolve the 0.05 mmol / L precursor bismuth nitrate in a mixed solution of DMF and acetonitrile, and stir for 10 min to dissolve it. The stirring speed is 500 r / min to obtain precursor solution A. The volume ratio of DMF to acetonitrile in solution A is 4:1.

[0054] Step 2: Dissolve the precursor platinum salt, precursor cobalt salt, precursor copper salt, and precursor nickel salt in solution A at a molar ratio of 1:1:1:1 to obtain solution B. Stir the solution B at a speed of 500 r / min for 20 min. The molar ratio of the precursor platinum ions, bismuth ions, cobalt ions, copper ions, and nickel ions is 1:2:1:1:1. The precursor platinum salt is chloroplatinic acid and / or potassium chloroplatinate; the precursor bismuth salt is bismuth nitrate; the precursor cobalt salt is cobalt chloride; the precursor copper salt is copper chloride; and the precursor nickel salt is nickel chloride.

[0055] Step 3: Soak a piece of carbon cloth in acetone solution and deionized water in sequence and sonicate for 30 minutes. Then air dry at room temperature and clamp it on the clip electrode, leaving an area of ​​1*1cm. The three-electrode system consisting of a saturated calomel electrode as the reference electrode, a platinum mesh electrode as the counter electrode, and the clip electrode as the working electrode is immersed in solution B.

[0056] Step 4: Set the program of the Koster CS350M electrochemical workstation to time-current test, set the constant potential to -0.5V, and set the time to 1800s;

[0057] Step 5: Remove the electrodeposited carbon cloth, rinse it with deionized water, and vacuum dry it at 60°C for 1 hour to obtain the Pt1Bi2Co1Cu1Ni1 / CC composite material.

[0058] The obtained Pt1Bi2Co1Cu1Ni1 / CC composite material was observed using a scanning electron microscope (SEM), as follows: Figure 1 As shown in Figure a, the obtained Pt1Bi2Co1Cu1Ni1 / CC composite material is composed of a large number of nanosheets. Meanwhile, as... Figure 2The transmission electron microscope can be seen from the transmission electron microscope of the obtained Pt1Bi2Co1Cu1Ni1 / CC composite material; wherein a is under a transmission electron microscope, and b is an energy spectrum corresponding to an element;

[0059] The Pt1Bi2Co1Cu1Ni1 / CC composite material obtained above is detected by X-ray photoelectron spectroscopy. It can be seen from the total spectrum of XPS that the five elements of Pt, Bi, Co, Cu and Ni are reduced, which proves the successful synthesis of Pt1Bi2Co1Cu1Ni1 high-entropy alloy.

[0060] Example 3:

[0061] A method for synthesizing a Pt-based nano high-entropy alloy on a carrier, specifically comprising the following steps:

[0062] First step: in a 50 mL flask, dissolve 0.05 mmol of bismuth salt precursor bismuth nitrate in a mixed solution of DMF and acetonitrile, stir for 5 min to dissolve, the stirring speed is 500 r / min, obtain precursor solution A, the volume ratio of DMF and acetonitrile in solution A is 4:1;

[0063] Second step: dissolve the precursor platinum salt, the precursor cobalt salt, the precursor copper salt and the precursor nickel salt in solution A according to the molar ratio of 1:1:1:1, obtain solution B and stir, control the stirring speed at 500 r / min, the stirring time is controlled at 15 min, the molar ratio of the precursor platinum ion, bismuth ion, cobalt ion, copper ion and nickel ion is 1:2:1:1:1, dissolved in solution A, the precursor platinum salt is chloroplatinic acid and / or potassium chloroplatinate; the precursor bismuth salt is bismuth nitrate; the precursor cobalt salt is cobalt chloride; the precursor copper salt is copper chloride and the nickel salt is nickel chloride;

[0064] Third step: immerse a piece of carbon cloth in acetone solution and deionized water for ultrasonic treatment for 30 min. Then dry at room temperature, and clamp on a clamping electrode, reserve an area of 1*1 cm, immerse a three-electrode system composed of a saturated calomel electrode as a reference electrode, a platinum mesh electrode as a counter electrode and a clamping electrode as a working electrode in solution B;

[0065] Fourth step: set the program of the Koster CS350M electrochemical workstation to chronoamperometry test, set the constant potential to-0.45V to-0.5V, and set the time to 1200s-1800s;

[0066] Fifth step: take out the carbon cloth after electrodeposition, rinse with deionized water, vacuum dry at 60°C for 0.5h, and obtain the Pt1Bi2Co1Cu1Ni1 / CC composite material.

[0067] In conclusion, the Pt1Bi2Co1Cu1Ni1 prepared by the preparation method has good catalytic activity for methanol oxidation reaction, namely, good MOR activity and excellent stability, and the preparation process is simple, low in cost and convenient for industrialized scale production.

[0068] The foregoing description has sufficiently disclosed the specific embodiments of the application. It is noted that any modification of the specific embodiments of the application by those skilled in the art that are not departing from the scope of the claims of the application will be encompassed by the scope of the application. Accordingly, the scope of the claims of the application is not only limited to the foregoing specific embodiments.

Claims

1. A method for synthesizing Pt-based nano-high-entropy alloys on a support, characterized in that, The specific steps are as follows: Step 1: Dissolve 0.05 mmol / L of the precursor bismuth salt in a mixed solution of DMF and acetonitrile, and stir for 5-10 min to dissolve it, with a stirring speed of 500 r / min, to obtain precursor solution A; Step 2: Dissolve the precursor platinum salt, precursor cobalt salt, precursor copper salt and precursor nickel salt in solution A in a molar ratio of 1:1:1:1 to obtain solution B and stir it. Control the stirring speed at 500 r / min and the stirring time at 10-20 min. Step 3: Soak a piece of carbon cloth in acetone solution and deionized water in sequence and sonicate for 30 min. Then dry it at room temperature and clamp it on the clip electrode, leaving an area of ​​1*1 cm. The three-electrode system consisting of a saturated calomel electrode as the reference electrode, a platinum mesh electrode as the counter electrode, and a clip electrode as the working electrode is immersed in solution B. Step 4: Set the program of the Koster CS350M electrochemical workstation to time-current test, set the constant potential to between -0.45V and -0.5V, and set the time to 1200s-1800s; Step 5: Remove the electrodeposited carbon cloth, rinse it with deionized water, and vacuum dry it at 60°C for 1 hour; In the precursor solution B, the concentrations of platinum ions, cobalt ions, copper ions, and nickel ions are 0.025 mmol / L, the preset molar ratio of precursor platinum salt to precursor bismuth salt is 1:2, and the volume ratio of DMF to acetonitrile in solution A is 4:1-3. In the second step, the molar ratio of the precursors platinum ions, bismuth ions, cobalt ions, copper ions and nickel ions is 1:2:1:1:1, and they are dissolved in solution A.

2. The method for synthesizing Pt-based nano-high-entropy alloys on a support according to claim 1, characterized in that: The precursor platinum salt is chloroplatinic acid and / or potassium chloroplatinate; the precursor bismuth salt is bismuth nitrate; the precursor cobalt salt is cobalt chloride; the precursor copper salt is copper chloride; and the precursor nickel salt is nickel chloride.

3. The method for synthesizing Pt-based nano-high-entropy alloys on a support according to claim 1, characterized in that: The electrodeposition temperature of the Koster CS350M electrochemical workstation is room temperature.

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