PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles, and preparation method and application thereof

Abstract

The application discloses a preparation method of PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles, and specifically comprises the following steps: mixing a platinum precursor, rhodium chloride hydrate, palladium chloride, iridium chloride hydrate and chloroauric acid to form a noble metal precursor, and then dissolving the noble metal precursor in triethylene glycol to form a precursor solution; dissolving a protective agent in triethylene glycol, adding the precursor solution drop by drop after heating and stirring, and then cooling to room temperature to obtain a high-entropy alloy nanoparticle sol; dissolving a carrier material in ethanol, carrying out constant-temperature ultrasonic treatment and crushing treatment, adding the high-entropy alloy nanoparticle sol and then carrying out crushing treatment again, and then sequentially carrying out stirring, washing and drying to obtain a product. The application further discloses the PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles. The high-entropy alloy nanoparticles synthesized by the method have high intrinsic catalytic activity, can accelerate the kinetics of an ethanol oxidation reaction, and the nanoscale high-entropy alloy has a large surface area and high stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of preparation process of nanoscale catalyst and energy conversion materials, and particularly relates to a PtRhPdIrAu / C noble metal high-entropy alloy nanoparticle and a preparation method and application thereof. BACKGROUND

[0002] Today's society is facing huge energy demand and environmental pollution problems, and developing green and clean energy conversion path is a key issue to improve the sustainability of social development. Ethanol fuel cell is an extremely promising electrochemical energy conversion device, and has received extensive attention in recent years due to its huge application potential. Compared with methanol, ethanol has lower toxicity. The complete oxidation of ethanol is accompanied by the transfer of 12 electrons / protons, so it has a high theoretical energy density. However, in practical application, the complete oxidation of ethanol is very difficult. For example, the complete breaking of C-C bond and the dehydrogenation of C1 and C2 products require high energy, and the oxidation product CO may cover the active sites, causing poisoning. Pt-based and Pd-based catalysts are currently the best ethanol oxidation catalysts. It is reported that alloying Pt and Pd can modulate the electronic environment of the metal surface, thereby optimizing the adsorption / desorption of reactants / intermediates and improving the reaction rate. The composition and proportion of alloying elements have a great exploration space, and screening of high-efficiency and stable multi-component catalysts is the bottleneck to break through the application of current alcohol energy conversion devices in many fields.

[0003] High-entropy alloy can be regarded as an alloy material containing 5 or more than 5 elements, and the mole percentage of each element is 5% to 35%. High-entropy alloy has a unique high-entropy effect, and can still maintain the stability of the structure in high current density and corrosive electrolyte. In recent years, there has been some progress in the application of nanoscale high-entropy alloy in electrocatalytic conversion, which confirms that high-entropy alloy nanoparticles have application potential as high-efficiency electrocatalysts. In the process of preparing nanoscale high-entropy alloy catalyst, the most critical step is to reduce multiple precursors under suitable reduction conditions. The currently reported preparation process of high-entropy alloy nanoparticles is complex and the intrinsic catalytic activity is poor. SUMMARY

[0004] In order to overcome the deficiencies existing in the prior art, the purpose of the present application is to provide a preparation method of PtRhPdIrAu / C noble metal high-entropy alloy nanoparticle, which solves the problems of complex preparation process of high-entropy alloy nanoparticle and poor catalytic activity.

[0005] Another purpose of the present application is to provide a PtRhPdIrAu / C noble metal high-entropy alloy nanoparticle.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] A preparation method of PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles, the specific steps are as follows:

[0008] (1) mixing platinum precursor, rhodium chloride hydrate, palladium chloride, iridium chloride hydrate and chloroauric acid to form a noble metal precursor, then dissolving the noble metal precursor in triethylene glycol to form a precursor solution; dissolving a protective agent in triethylene glycol, heating to 160-240℃, adding the precursor solution dropwise and stirring, then cooling to room temperature to obtain a high-entropy alloy nanoparticle sol;

[0009] (2) dissolving a carrier material in ethanol, then performing constant temperature ultrasonic treatment and crushing treatment, adding the high-entropy alloy nanoparticle sol prepared above and performing crushing treatment again, then sequentially performing stirring, washing and drying to obtain PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles.

[0010] Preferably, the molar ratio of platinum precursor, rhodium chloride hydrate, palladium chloride, iridium chloride hydrate and chloroauric acid is equal.

[0011] Preferably, the volume ratio of the noble metal precursor to the triethylene glycol is 1:3-9.

[0012] Preferably, the molar ratio of the protective agent to the noble metal precursor is 2-20:1.

[0013] Preferably, the platinum precursor is any one of platinum tetrachloride, chloroplatinic acid or platinum acetylacetonate.

[0014] Preferably, the protective agent is any one of polyvinylpyrrolidone, cetyltrimethylammonium bromide or triblock copolymer.

[0015] Preferably, in the stirring process in step (1), the rotation speed is 200-800 rpm.

[0016] Preferably, in the stirring process in step (1), the stirring time is 12-18 h.

[0017] Preferably, in the process of adding the precursor solution dropwise, the dropwise adding speed is 2-240 ml / h.

[0018] Preferably, the carrier material is any one of VXC-72R conductive carbon black, ordered mesoporous carbon, γ-Al2O3 or nitrogen-doped carbon nanotube.

[0019] More preferably, the carrier material is VXC-72R conductive carbon black.

[0020] Preferably, the mass ratio of the carrier material to the noble metal precursor is 3-20:1.

[0021] Preferably, the washing process is a mixture of ultrapure water and anhydrous ethanol or any one of the following mixtures: acetone, diethyl ether, ethanol and ultrapure water.

[0022] Preferably, the number of washing times is more than 5 to 20 times.

[0023] Preferably, the specific steps of the crushing process are as follows:

[0024] The carrier material dissolved in ethanol is placed in a cell crusher, and ultrasonic crushing treatment is performed by a 10mm diameter amplitude rod for 1h.

[0025] Preferably, the loading amount of the PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles is 5%-15%.

[0026] Preferably, the ultrasonic treatment time is more than 3h.

[0027] Preferably, the particle size of the PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles is 5-10nm.

[0028] A PtRhPdIrAu / C noble metal high-entropy alloy nanoparticle is prepared by the preparation method of the PtRhPdIrAu / C noble metal high-entropy alloy nanoparticle.

[0029] A PtRhPdIrAu / C noble metal high-entropy alloy nanoparticle is applied as an anode material of an ethanol fuel cell.

[0030] The present application has the following advantages and beneficial effects compared with the prior art:

[0031] The PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles synthesized by the method have high intrinsic catalytic activity, which can accelerate the kinetics of ethanol oxidation reaction. The nanoscale high-entropy alloy has a large surface area, high stability and unique synergistic effect between multiple metals. Pt, Rh, Pd, Ir and Au, five metal elements form a single-phase crystal structure dominated by (111) surface. Different atomic size elements produce significant compression / tension stress between the crystal lattices. Strain effect causes the thermodynamic non-equilibrium state of the alloy and leads to higher potential energy, thereby reducing the energy barrier in the catalytic reaction. The performance of high-entropy alloy is not the sum of the characteristics of each element, but has complex interactions. For ethanol oxidation reaction, it is necessary to balance the increase of lattice spacing, promote ethanol adsorption and strengthen the resistance to CO poisoning.

[0032] The present application adopts one-pot method to obtain preset amount of noble metal high-entropy alloy nanoparticles, and has simple preparation process, high safety in operation process, no pollution, and is convenient for large-scale synthesis and loading on various carrier materials. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The TEM image of the PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles.

[0034] Figure 2 The X-ray diffraction patterns of the PtRhPdIrAu / C, PtRhPdIrRu / C, PtRhPdIrRuAu / C and PtRhPdIrRuAuAg / C noble metal high-entropy alloy nanoparticles prepared in Examples 1-4.

[0035] Figure 3 The linear sweep voltammetry (LSV) curves of the ethanol oxidation reaction of the PtRhPdIrAu / C, PtRhPdIrRu / C, PtRhPdIrRuAu / C and PtRhPdIrRuAuAg / C noble metal high-entropy alloy nanoparticles prepared in Examples 1-4.

[0036] Figure 4 The lattice spacing-current density relationship diagram and the fitting curve of the PtRhPdIrAu / C, PtRhPdIrRu / C, PtRhPdIrRuAu / C and PtRhPdIrRuAuAg / C noble metal high-entropy alloy nanoparticles prepared in Examples 1-4.

[0037] Figure 5 The cyclic voltammetry (CV) scan comparison diagram of the ethanol oxidation reaction of the PtRhPdIrAu / C high-entropy alloy nanoparticles prepared in the present application and the commercial Pt / C and Pd / C catalysts. DETAILED DESCRIPTION

[0038] The inventive purpose of the present application will be further described in detail in combination with the drawings and specific examples, and the examples cannot be described one by one here, but the embodiments of the present application are not limited to the following examples.

[0039] Example 1

[0040] Take 300 mg of polyvinylpyrrolidone (PVP) and dissolve it in 120 ml of triethylene glycol reducing agent, and mark it as solution A. Accurately take 0.04 mM of platinum chloride, rhodium chloride hydrate, palladium chloride, iridium chloride hydrate and gold chloride noble metal precursors respectively, and add them to 40 ml of triethylene glycol, and ultrasonically mix for about 15 min until the noble metal precursors are completely dissolved, and mark it as solution B. Take a certain amount of VXC-72R conductive carbon black, dissolve it in 40 ml of anhydrous ethanol, and ultrasonically treat it at 55°C for 3 h, and break it up for 1 h, and mark it as solution C. Pour solution A into a round-bottom flask, add an olive-shaped magnet, and pass in argon as a protective gas, and gradually heat it to 230°C in an oil bath, and keep it for 15 min. Place solution B in a syringe, and inject it drop by drop into the round-bottom flask at a dropping speed of 120 ml / h, and keep the temperature between 227°C; after the injection is completed, cool it to room temperature, and obtain a black-brown PtRhPdIrAu high-entropy alloy nanoparticle sol. Pour solution C into the obtained PtRhPdIrAu high-entropy alloy nanoparticle sol, break it up again for 1 h, and then stir overnight. Finally, use ultrapure water and anhydrous ethanol to clean it several times, and centrifuge it at a speed of 10,000 rpm, take the precipitate and dry it, and obtain PtRhPdIrAu / C high-entropy alloy nanoparticles. The transmission electron microscope image of the PtRhPdIrAu / C high-entropy alloy nanoparticles is shown in FIG. 1. Figure 1

[0041] Accurately take 10 mg of PtRhPdIrAu / C high-entropy alloy nanoparticles, add 5 ml of a mixed solution (ethanol: ultrapure water: 0.5% Nafion = 9:1:0.5) to dissolve it, and configure it into a catalyst dispersion liquid, and mark it as solution D. Treat solution D in an ultrasonic system for 1 h, and then take 2.5 ul and apply it to a glassy carbon electrode with an area of 0.196 cm 2 The working electrode is placed in a rotating disc device, and immersed in a 0.1M KOH+0.5M ethanol electrolyte for CV testing, at a speed of 1600 rpm, a scan rate of 50 mV / s, and a scan potential range of -0.13V to 1.01V (relative to the reversible hydrogen potential), as shown in FIG. 2. Figure 3

[0042] Example 2

[0043] ​​Take 300 mg of polyvinylpyrrolidone (PVP) and dissolve it in 120 ml of triethylene glycol reducing agent, labeled as solution A. Accurately transfer 0.04 mM of chloroplatinic acid, rhodium chloride hydrate, palladium chloride, iridium chloride hydrate, and ruthenium chloride hydrate noble metal precursors, respectively, into 40 ml of triethylene glycol, and mix uniformly under ultrasonic for about 15 min until the noble metal precursors are completely dissolved, labeled as solution B. Take a certain amount of VXC-72R conductive carbon black, dissolve it in 40 ml of anhydrous ethanol, and ultrasonically treat it at 55°C for 3 h, and then break it up for 1 h, labeled as solution C. Pour solution A into a round-bottom flask, add an olive-shaped magnet, and pass in argon as a protective gas. Gradually heat it to 200°C in an oil bath, and keep it at this temperature for 15 min. Place solution B in a syringe, and inject it drop by drop into the round-bottom flask using the injection method at a dropwise addition rate of 120 ml / h, keeping the temperature between 160°C; after the injection is complete, cool it to room temperature, and obtain a black-brown PtRhPdIrRu high-entropy alloy nanoparticle sol. Pour solution C into the obtained PtRhPdIrRu high-entropy alloy nanoparticle sol, break it up again for 1 h, and then stir overnight. Finally, wash it multiple times with ultrapure water and anhydrous ethanol, and centrifuge it at a speed of 10,000 rpm, take the precipitate, and dry it, and you can obtain PtRhPdIrRu / C high-entropy alloy nanoparticles.

[0044] Example 3

[0045] Take 300 mg of polyvinylpyrrolidone (PVP) and dissolve it in 120 ml of triethylene glycol reducing agent, labeled as solution A. Accurately transfer 0.04 mM of chloroplatinic acid, rhodium chloride hydrate, palladium chloride, iridium chloride hydrate, and ruthenium chloride hydrate noble metal precursors, respectively, into 40 ml of triethylene glycol, and mix uniformly under ultrasonic for about 15 min until the noble metal precursors are completely dissolved, labeled as solution B. Take a certain amount of VXC-72R conductive carbon black, dissolve it in 40 ml of anhydrous ethanol, and ultrasonically treat it at 55°C for 3 h, and then break it up for 1 h, labeled as solution C. Pour solution A into a round-bottom flask, add an olive-shaped magnet, and pass in argon as a protective gas. Gradually heat it to 200°C in an oil bath, and keep it at this temperature for 15 min. Place solution B in a syringe, and inject it drop by drop into the round-bottom flask using the injection method at a dropwise addition rate of 120 ml / h, keeping the temperature between 160°C; after the injection is complete, cool it to room temperature, and obtain a black-brown PtRhPdIrRu high-entropy alloy nanoparticle sol. Pour solution C into the obtained PtRhPdIrRu high-entropy alloy nanoparticle sol, break it up again for 1 h, and then stir overnight. Finally, wash it multiple times with ultrapure water and anhydrous ethanol, and centrifuge it at a speed of 10,000 rpm, take the precipitate, and dry it, and you can obtain PtRhPdIrRu / C high-entropy alloy nanoparticles.

[0046] Example 4

[0047] Weigh 300 mg of polyvinylpyrrolidone (PVP) and dissolve it in 120 ml of triethylene glycol reducing agent, and record this as solution A. Accurately transfer 0.03 mM of chloroplatinic acid, hydrated rhodium chloride, palladium chloride, hydrated iridium chloride, hydrated ruthenium chloride, chloroauric acid, and silver chloride noble metal precursors to 40 ml of triethylene glycol, and sonicate for approximately 15 min until the noble metal precursors are completely dissolved; record this as solution B. Weigh a certain amount of VXC-72R conductive carbon black and dissolve it in 40 ml of anhydrous ethanol. Sonicate at 55 °C for 3 h, and then break it up for 1 h; record this as solution C. Pour solution A into a round-bottom flask, add an olive-shaped magnetic stir bar, and purge with argon gas as a protective gas. Gradually heat the flask to 240 °C in an oil bath and maintain this temperature for 15 min. Solution B was placed in a syringe and injected dropwise into a round-bottom flask at a rate of 120 ml / h, maintaining the temperature between 235℃ and 240℃. After injection, the mixture was cooled to room temperature to obtain a dark brown PtRhPdIrRuAuAg high-entropy alloy nanoparticle sol. Solution C was poured into the obtained PtRhPdIrRuAuAg high-entropy alloy nanoparticle sol, and the mixture was subjected to further disruption for 1 hour, followed by stirring overnight. Finally, the mixture was washed multiple times with ultrapure water and anhydrous ethanol, centrifuged at 10,000 rpm, and the precipitate was dried to obtain PtRhPdIrRuAuAg / C high-entropy alloy nanoparticles.

[0048] Transmission electron microscopy (TEM) images of PtRhPdIrAu / C high-entropy alloy nanoparticles by [author's name missing]. Figure 1 As shown, by Figure 1 It is known that the PtRhPdIrAu / C high-entropy alloy nanoparticles have a particle size of 5-10 nm and are uniformly dispersed on the carbon black support without obvious agglomeration. The tiny nanoscale alloy particles can provide a large specific surface area, and the uniform dispersion of the particles is beneficial to further increase the active area and optimize the mass transfer of the reaction process.

[0049] The X-ray diffraction patterns of the noble metal high-entropy alloy nanoparticles prepared in Examples 1-4 are as follows: Figure 2 As shown, by Figure 2 It can be seen that the lattice spacings of PtRhPdIrAu, PtRhPdIrRu, PtRhPdIrRuAu, and PtRhPdIrRuAuAg are respectively and The four synthesized high-entropy alloy nanoparticles are all face-centered cubic system, Fm-3m space group, and each crystal face does not show the characteristic peak of single metal, but the intermediate state of the single metal card contained in the element, that is, a single-phase solid solution crystal structure. Among them, the (111) face accounts for the highest proportion in all crystal face types. The single crystal structure means that various elements are uniformly dispersed in the particles, and the high dispersion of each element brings enhanced high-entropy effect, and the stability of the crystal structure is increased.

[0050] The linear sweep voltammetry (LSV) curves of the ethanol oxidation reaction of the noble metal high-entropy alloy nanoparticles prepared in Examples 1-4 are shown in Figure 3 It can be seen from Figure 3 that the LSV curves of the ethanol oxidation of high-entropy alloys with different element combinations have obvious differences. In the linear voltammetry curve, the greater the current density, the faster the ethanol oxidation rate, the lower the initial potential, that is, the point of starting to climb is more left, indicating that the oxidation potential of ethanol oxidation is lower, and the required activation energy is smaller. The ethanol oxidation of the five-element PtRhPdIrAu / C has low initial potential and large electro-oxidation current, showing excellent ethanol electro-oxidation activity. If Au is replaced by Ru, the ethanol electro-oxidation activity of the five-element PtRhPdIrRu / C decreases sharply, because Ru intensifies the adsorption of toxic CO species, leading to the inability to oxidize the toxic intermediate in time and causing activity decline. If Au is added to the five-element PtRhPdIrRu / C to form a six-element PtRhPdIrRuAu / C, the d-orbital electron occupation number of Au is high, which weakens the adsorption of the alloy system to CO and inhibits the poisoning effect, so the ability to continue to oxidize ethanol is enhanced. If Ag is added to the six-element PtRhPdIrRuAu / C to form a seven-element PtRhPdIrRuAuAg / C, the introduction of Ag enhances the adsorption of OH species, so the initial potential can be further shifted negatively, but Ag does not strongly adsorb ethanol and oxidation intermediates, resulting in a small peak current in the CV positive scan segment.

[0051] The lattice spacing-current density relationship diagram and its fitting curve of the high-entropy alloy nanoparticles prepared in Examples 1-4 at a potential of 0.4V are shown in Figure 4 It can be seen from Figure 4 that when E=0.4V, the lattice spacing increases, and its current density also increases. That is, the larger the lattice spacing, the easier the ethanol oxidation activation, so the element combination should first increase the lattice spacing appropriately, and the atomic radius of Ru is the smallest among noble metals. Although Ag can quickly activate the ethanol oxidation reaction, Ag does not strongly adsorb ethanol intermediates and strongly adsorbs toxic CO. Therefore, PtRhPdIrAu is the optimal combination.

[0052] The CV comparison chart of ethanol oxidation reaction of PtRhPdIrAu / C high-entropy alloy nanoparticles and commercial Pt / C and Pd / C catalysts is shown in FIG. 2, from which it can be seen that the ethanol oxidation onset potential of PtRhPdIrAu / C is only 0.31 V, and the peak current density reaches 6.22 mA cm Figure 5 Figure 5 -2, which are all better than the commercial Pt / C and commercial Pd / C. -2

[0053] The above specific embodiments are the preferred embodiments of the present application, and cannot limit the present application, and any changes or other equivalent replacement manners made without departing from the technical solutions of the present application are included in the protection scope of the present application.​​

Claims

1. A method for preparing PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles, characterized in that, The specific steps are as follows: (1) mixing platinum precursor, rhodium chloride hydrate, palladium chloride, iridium chloride hydrate and chloroauric acid to form a noble metal precursor, then dissolving the noble metal precursor in triethylene glycol to form a precursor solution; dissolving a protective agent in triethylene glycol and heating to 160-240℃, then adding the precursor solution dropwise and stirring, then cooling to room temperature to obtain a high-entropy alloy nanoparticle sol; (2) dissolving a carrier material in ethanol and performing constant temperature ultrasonic treatment and crushing treatment, then adding the high-entropy alloy nanoparticle sol prepared above and performing crushing treatment again, then sequentially performing stirring, washing and drying to obtain PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles; The platinum precursor is chloroplatinic acid; The protective agent is polyvinylpyrrolidone; The volume ratio of the noble metal precursor to the triethylene glycol is 1:3-9; The molar ratio of the protective agent to the noble metal precursor is 2-20:1; The mass ratio of the carrier material to the noble metal precursor is 3-20:1; The carrier material is any one of VXC-72R conductive carbon black, ordered mesoporous carbon, γ-Al2O3 or nitrogen-doped carbon nanotubes; In the PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles, Pt, Rh, Pd, Ir and Au form a single-phase solid solution crystal structure; The PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles are applied to ethanol electro-oxidation reactions.

2. The preparation method of the PtRhPdIrAu / C noble metal high-entropy alloy nanoparticles according to claim 1, characterized in that, In the washing process, the washing agent is any one of a mixture of ultrapure water and anhydrous ethanol or a mixture of acetone, diethyl ether, ethanol and ultrapure water.

3. A PtRhPdIrAu / C noble metal high-entropy alloy nanoparticle, characterized in that, Prepared by the preparation method of claim 1-2.

4. The use of a PtRhPdIrAu / C noble metal high-entropy alloy nanoparticle according to claim 3, characterized in that, As an anode material for ethanol fuel cells.

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