Multi-twin-crystal palladium-based material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of chemistry, and discloses a palladium-based material and a preparation method and application thereof, and the palladium-based material has a regular icosahedron multiple twin crystal structure; the preparation method comprises the following steps: (1) by taking diethylene glycol as a solvent, polyvinylpyrrolidone as a morphology guiding agent and sodium tetrachloropalladate as metal precursor salt, carrying out solvothermal reaction to obtain black Pd nanocrystals with an icosahedron structure; (2) loading the Pd nanocrystal on activated carbon in a solvent of water and ethanol, then using K2PtCl4 as a metal precursor salt, and introducing Br <-> to slow down kinetics, so that Pt selectively grows on the vertex of a Pd icosahedron to obtain the Pd-based nanocrystal for selectively growing Pt; and (3) introducing Ga into the crystal by utilizing gallium acetylacetonate to modify the crystal, and calcining and reducing in an inert atmosphere to obtain the palladium-based nanocrystalline material, according to the gallium-modified palladium-based material, by optimizing a Pd crystal structure and introducing twin crystal boundaries, the catalytic activity of the material on anodic ethanol oxidation reaction is improved.

Description

Technical Field

[0001] The present invention relates to the field of chemical technology, and particularly to a palladium-based material with multiple twins, a preparation method thereof, and an application thereof. Background Art

[0002] A fuel cell is an efficient and environmentally friendly energy device that can directly convert the chemical energy stored in fuel into electrical energy. Common fuels in fuel cells include hydrogen, methanol, ethanol, formic acid, etc. Direct ethanol fuel cells (DEFCs), as a promising energy conversion device, have attracted much attention because they meet the requirements of green chemistry. However, the low activity of the anode catalyst for ethanol oxidation is a major obstacle to the commercialization of ethanol fuel cells. Therefore, it is imperative to develop more efficient and stable anode catalysts. Based on this, the research and development of electrocatalysts for ethanol oxidation (EOR) with high activity and high stability have broad application prospects and have become a hot research topic.

[0003] Research shows that palladium-based materials are efficient EOR electrocatalysts. Due to their low C-C bond cleavage efficiency, low oxygen affinity, and strong adsorption ability for toxic intermediates, they have been widely used in the research field of anode EOR in recent years. At present, adjusting the electronic structure of palladium with other metals to construct multi-site metal catalysts is more conducive to the ethanol oxidation reaction than pure palladium site catalysts. In order to construct electrocatalysts with a large active area and excellent uniformity, we usually synthesize small-sized metal nanoparticles. Therefore, developing an effective synthesis strategy to construct multi-site metal catalysts plays a crucial role in the development of ethanol fuel cells. Summary of the Invention

[0004] To solve the problems raised in the above background art, the purpose of the present invention is to provide a palladium-based metal nanomaterial that can improve the catalytic efficiency of ethanol oxidation reaction, a preparation method thereof, and an application of the palladium-based metal nanoparticles in the catalytic oxidation of ethanol.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a palladium-based material with multiple twins, which is a PdPtGa nanocrystal supported on an activated carbon carrier. The PdPtGa nanocrystal has an icosahedral multiple twin structure. In the PdPtGa nanocrystal, Pt atoms selectively grow at the vertices of the Pd icosahedron, and Ga atomic sites are evenly distributed on the multiple twins. Pd and Pt in the PdPtGa nanocrystal mainly exist in the zero-valent form, Ga mainly forms metal bonds with Pd and Pt, and part of Ga is oxidized.

[0007] The present invention also provides a preparation method of the palladium-based material with multiple twins as described above, including the following steps:

[0008] (1) Dissolve polyvinylpyrrolidone and sodium tetrachloropalladate in diethylene glycol and conduct a solvothermal reaction to obtain black Pd icosahedral nanocrystals with a multiple twin structure;

[0009] (2) Dissolve the black Pd icosahedral nanocrystals, polyvinylpyrrolidone, ascorbic acid, potassium bromide, and potassium chloroplatinate in water and react to obtain Pd-based nanocrystals with selectively grown Pt; load Pd nanocrystals on activated carbon in water, then use K2PtCl4 as the metal precursor salt and introduce Br - Slow down the kinetics to enable selective growth of Pt at the vertices of the Pd icosahedron, obtaining Pd-based nanocrystals with selectively grown Pt;

[0010] (3) Add gallium acetylacetonate to the Pd-based nanocrystals with selectively grown Pt, use gallium acetylacetonate to introduce Ga to modify the crystals, after reacting at room temperature, centrifuge and dry, and then calcine and reduce in an inert atmosphere to obtain a Ga-PdPt nanocrystal material.

[0011] Furthermore, in step (1), the mass-volume ratio of polyvinylpyrrolidone to diethylene glycol is 25-30:1; the mass-volume ratio of sodium tetrachloropalladate to diethylene glycol is 31:6.

[0012] Furthermore, in step (1), the temperature of the solvothermal reaction is 120-130 °C and the time is 3-4 h.

[0013] Furthermore, in step (2), the mass ratio of sodium tetrachloropalladate, polyvinylpyrrolidone, ascorbic acid, potassium bromide, and potassium chloroplatinate in step (1) is 1:11-11.5:7-9:0.5-0.6:0.08-0.25.

[0014] Furthermore, in step (3), the mass ratio of gallium acetylacetonate to sodium tetrachloropalladate in step (1) is 1:30-35.

[0015] Furthermore, in step (3), the specific conditions for calcination and reduction are: program temperature rise to 250-400 °C at 0.5-5 °C / min -1 for heat treatment and maintain at this temperature for 1-7 h.

[0016] The present invention also provides an application of the multiple twin palladium-based material as described above in the ethanol oxidation reaction.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] The present invention constructs palladium-based nanocrystals with a multiple twin structure, introduces twin grain boundaries, and has high intrinsic activity, enabling Pd Ihs to have good ethanol oxidation catalytic performance. The obtained PdPtGa Ihs of the present invention has multiple twin interfaces, which improves the electrocatalytic activity of the material for ethanol oxidation.

[0019] In the present invention, Br in potassium bromide is introduced - By delaying the reduction of the Pt precursor and restricting surface diffusion, Pt atoms can be selectively grown on the vertices of Pd icosahedral particles, thereby forming uniform Pt dots with a small size and a multiple twin structure.

[0020] The doping of Ga atoms in the present invention regulates the electronic structure of the twins, brings stronger metal interactions, and promotes the adsorption of hydroxide ions.

[0021] The preparation method of the present invention is simple and easy to industrialize. The prepared PdPtGa Ihs has more excellent electrocatalytic performance and stability for ethanol oxidation reaction in acidic and alkaline media. It is a very promising fuel cell catalyst and has broad application prospects in the future energy industry. Description of the Drawings

[0022] Figure 1 HRTEM image of PdPtGa Ihs prepared in Example 3;

[0023] Figure 2 Magnified HRTEM image of PdPtGa Ihs prepared in Example 3;

[0024] Figure 3 Mapping image of PdPtGa Ihs prepared in Example 3;

[0025] Figure 4 XPS spectrum of PdPtGa Ihs prepared in Example 3;

[0026] Figure 5 CV curves (5a) and mass-specific activities (5b) of the catalytic materials prepared in Example 3, Comparative Example 1, and commercial 20% Pd / C catalyst in 0.5 M H2SO4, and CV curves (5c) and mass-specific activities (5d) in 0.5 M H2SO4 and 1.0 M ethanol;

[0027] Figure 6 CV curves (6a) of the catalytic materials prepared in Example 3, Comparative Example 1, and commercial 20% Pd / C catalyst in 1.0 M KOH and CV curves in 1.0 M KOH and 1.0 M ethanol;

[0028] Figure 7Accelerated durability test chart (7a) of PdPtGa Ihs prepared in Example 3 and TEM chart (7b) of the sample after the test;

[0029] Figure 8 TEM chart of the catalytic material prepared in Comparative Example 2;

[0030] Figure 9 TEM chart of the catalytic material prepared in Comparative Example 3. Detailed implementation mode

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] Example 1

[0033] The preparation method of the palladium-based nanocrystal material described in the present invention includes the following steps:

[0034] (1) Preparation of Pd icosahedral nanocrystals: Dissolve 150 mg of polyvinylpyrrolidone (PVP, C6H9NO) n in 4 mL of diethylene glycol (C4H 10 O3), then magnetically stir in an oil bath and preheat at 120 °C for 20 min. Subsequently, add 2 mL of sodium tetrachloropalladate (Na2PdCl4, concentration 15.5 mg mL -1 ) using diethylene glycol as the solvent, stir and react at 1500 rpm for 3 h, then take out the sample, cool it, and centrifuge it with acetone and ethanol to obtain Pd icosahedral nanocrystals with a diameter of 15 nm, which are dispersed in 5 mL of deionized water for later use.

[0035] (2) Preparation of PdPt Ihs: Take the above Pd icosahedral nanocrystal solution, and at the same time weigh 350 mg of PVP and 250 mg of ascorbic acid (AA) and dissolve them in 20 mL of deionized water, and magnetically stir at 30 °C for 20 min. At the same time, dissolve 17.5 mg of potassium bromide (KBr) and 2.5 mg of potassium chloroplatinate (K2PtCl4) in 10 mL of deionized water, and add them to the above mixed solution at one time, react at 30 °C for 12 h, collect by centrifugal washing with acetone and ethanol, and disperse in 10 mL of deionized water for later use.

[0036] (3) Preparation of PdPtGa Ihs: Take the above PdPt Ihs solution, and add 1 mg of gallium acetylacetonate (C 15 H 21(GaO6), magnetically stir at room temperature for 12 h, centrifuge using acetone and ethanol, and dry in a vacuum drying oven. Under a nitrogen atmosphere, heat the above sample at a rate of 2 °C min -1 Program the temperature to rise to 300 °C for heat treatment, hold at this temperature for 2 h, and then cool to room temperature to obtain PdPtGa Ihs.

[0037] Example 2

[0038] For the palladium-based nanocrystal material described in the present invention, its preparation method includes the following steps:

[0039] (1) Preparation of Pd icosahedral nanocrystals: Dissolve 150 mg of polyvinylpyrrolidone (PVP, C6H9NO) n in 4 mL of diethylene glycol (C4H 10 O3), then magnetically stir in an oil bath and preheat at 120 °C for 20 min. Subsequently, add 2 mL of sodium tetrachloropalladate (Na2PdCl4, concentration 15.5 mg mL -1 ) using diethylene glycol as the solvent, take out the sample after stirring and reacting at 1500 rpm for 3 h, cool, and centrifuge using acetone and ethanol to obtain Pd icosahedral nanocrystals with a diameter of 15 nm, and disperse them in 5 mL of deionized water for later use.

[0040] (2) Preparation of PdPt Ihs: Take the above Pd icosahedral nanocrystal solution, and simultaneously weigh 350 mg of PVP and 250 mg of ascorbic acid (AA) and dissolve them in 20 mL of deionized water, and magnetically stir at 30 °C for 20 min. At the same time, dissolve 17.5 mg of potassium bromide (KBr) and 5 mg of potassium chloroplatinate (K2PtCl4) in 10 mL of deionized water, and add them to the above mixed solution at one time. React at 30 °C for 12 h, collect by centrifugal washing using acetone and ethanol, and disperse in 10 mL of deionized water for later use.

[0041] (3) Preparation of PdPtGa Ihs: Take the above PdPt Ihs solution, add 1 mg of gallium acetylacetonate (C 15 H 21 (GaO6), magnetically stir at room temperature for 12 h, centrifuge using acetone and ethanol, and dry in a vacuum drying oven. Under a nitrogen atmosphere, heat the above sample at a rate of 2 °C min -1 Program the temperature to rise to 300 °C for heat treatment, hold at this temperature for 2 h, and then cool to room temperature to obtain PdPtGa Ihs.

[0042] Example 3

[0043] For the palladium-based nanocrystal material described in the present invention, its preparation method includes the following steps:

[0044] (1) Preparation of Pd icosahedral nanocrystals: Dissolve 150 mg of polyvinylpyrrolidone (PVP, C6H9NO) n in 4 mL of diethylene glycol (C4H 10 O3), then stir magnetically in an oil bath and preheat at 120 °C for 20 min. Subsequently, add 2 mL of sodium tetrachloropalladate (Na2PdCl4, concentration 15.5 mg mL -1 ) with diethylene glycol as the solvent. After stirring and reacting at 1500 rpm for 3 h, take out the sample, cool it, and centrifuge with acetone and ethanol to obtain Pd icosahedral nanocrystals with a diameter of 15 nm, which are dispersed in 5 mL of deionized water for later use.

[0045] (2) Preparation of PdPt Ihs: Take the above Pd icosahedral nanocrystal solution, and at the same time weigh 350 mg of PVP and 250 mg of ascorbic acid (AA) and dissolve them in 20 mL of deionized water. Stir magnetically at 30 °C for 20 min. At the same time, dissolve 17.5 mg of potassium bromide (KBr) and 7.5 mg of potassium chloroplatinate (K2PtCl4) in 10 mL of deionized water, and add them to the above mixed solution at one time. React at 30 °C for 12 h, collect by centrifugal washing with acetone and ethanol, and disperse in 10 mL of deionized water for later use.

[0046] (3) Preparation of PdPtGa Ihs: Take the above PdPt Ihs solution, add 1 mg of gallium acetylacetonate (C 15 H 21 GaO6), stir magnetically at room temperature for 12 h, centrifuge with acetone and ethanol, and dry in a vacuum drying oven. Under a nitrogen atmosphere, heat the above sample at a rate of 2 °C min -1 to 300 °C for heat treatment, hold at this temperature for 2 h, and then cool to room temperature to obtain PdPtGa Ihs.

[0047] Example 4

[0048] The preparation method of the palladium-based nanocrystal material described in the present invention includes the following steps:

[0049] (1) Preparation of Pd icosahedral nanocrystals: Dissolve 150 mg of polyvinylpyrrolidone (PVP, C6H9NO) n in 4 mL of diethylene glycol (C4H 10 O3), then stir magnetically in an oil bath and preheat at 120 °C for 20 min. Subsequently, add 2 mL of sodium tetrachloropalladate (Na2PdCl4, concentration 15.5 mg mL -1) After stirring the reaction at 1500 rpm for 3 h, the sample was taken out, cooled, and centrifuged with acetone and ethanol to obtain Pd icosahedral nanocrystals with a diameter of 15 nm, which were dispersed in 5 mL of deionized water for later use.

[0050] (2) Preparation of PdPt Ihs: Take the above Pd icosahedral nanocrystal solution. At the same time, weigh 350 mg of PVP and 250 mg of ascorbic acid (AA) and dissolve them in 20 mL of deionized water, and magnetically stir for 20 min at 30 °C. At the same time, dissolve 17.5 mg of potassium bromide (KBr) and 7.5 mg of potassium chloroplatinate (K2PtCl4) in 10 mL of deionized water, and add them to the above mixed solution at one time. React at 30 °C for 12 h, and collect by centrifugal washing with acetone and ethanol, and disperse in 10 mL of deionized water for later use.

[0051] (3) Preparation of PdPtGa Ihs: Take the above PdPt Ihs solution, and add 1 mg of gallium acetylacetonate (C 15 H 21 GaO6). Magnetically stir at room temperature for 12 h, centrifuge with acetone and ethanol, and dry in a vacuum drying oven. Under a nitrogen atmosphere, heat-treat the above sample at a programmed heating rate of 2 °C min -1 to 350 °C and hold at this temperature for 2 h, and then cool to room temperature to obtain PdPtGa Ihs.

[0052] Example 5

[0053] The preparation method of the palladium-based nanocrystal material described in the present invention includes the following steps:

[0054] (1) Preparation of Pd icosahedral nanocrystals: Dissolve 150 mg of polyvinylpyrrolidone (PVP, C6H9NO) n in 4 mL of diethylene glycol (C4H 10 O3), and then magnetically stir in an oil bath and preheat at 120 °C for 20 min. Subsequently, add 2 mL of sodium tetrachloropalladate (Na2PdCl4, concentration 15.5 mg mL -1 ) with diethylene glycol as the solvent. After stirring the reaction at 1500 rpm for 3 h, the sample was taken out, cooled, and centrifuged with acetone and ethanol to obtain Pd icosahedral nanocrystals with a diameter of 15 nm, which were dispersed in 5 mL of deionized water for later use.

[0055] (2) Preparation of PdPt Ihs: Take the above Pd icosahedral nanocrystal solution. Meanwhile, weigh 350 mg of PVP and 250 mg of ascorbic acid (AA), dissolve them in 20 mL of deionized water, and stir magnetically at 30 °C for 20 min. Meanwhile, dissolve 17.5 mg of potassium bromide (KBr) and 7.5 mg of potassium chloroplatinate (K2PtCl4) in 10 mL of deionized water, add them to the above mixed solution at one time, react at 30 °C for 12 h, collect by centrifugal washing with acetone and ethanol, and disperse in 10 mL of deionized water for standby.

[0056] (3) Preparation of PdPtGa Ihs: Take the above PdPt Ihs solution, add 1 mg of gallium acetylacetonate (C 15 H 21 GaO6), stir magnetically at room temperature for 12 h, centrifuge with acetone and ethanol, and dry in a vacuum drying oven. Under a nitrogen atmosphere, heat the above sample at a rate of 2 °C min -1 to 400 °C for heat treatment, hold at this temperature for 2 h, and then cool to room temperature to obtain PdPtGa Ihs.

[0057] Example 6

[0058] The preparation method of the palladium-based nanocrystal material described in the present invention includes the following steps:

[0059] (1) Preparation of Pd icosahedral nanocrystals: Dissolve 150 mg of polyvinylpyrrolidone (PVP, C6H9NO) n in 4 mL of diethylene glycol (C4H 10 O3), then stir magnetically in an oil bath and preheat at 120 °C for 20 min. Subsequently, add 2 mL of sodium tetrachloropalladate (Na2PdCl4, concentration 15.5 mg mL -1 ) with diethylene glycol as the solvent, take out the sample after stirring and reacting at 1500 rpm for 3 h, cool, and centrifuge with acetone and ethanol to obtain Pd icosahedral nanocrystals with a diameter of 15 nm, and disperse in 5 mL of deionized water for standby.

[0060] (2) Preparation of PdPt Ihs: Take the above Pd icosahedral nanocrystal solution. Meanwhile, weigh 350 mg of PVP and 250 mg of ascorbic acid (AA), dissolve them in 20 mL of deionized water, and stir magnetically at 30 °C for 20 min. Meanwhile, dissolve 17.5 mg of potassium bromide (KBr) and 7.5 mg of potassium chloroplatinate (K2PtCl4) in 10 mL of deionized water, add them to the above mixed solution at one time, react at 30 °C for 12 h, collect by centrifugal washing with acetone and ethanol, and disperse in 10 mL of deionized water for standby.

[0061] (3) Preparation of PdPtGa Ihs: Take the above PdPt Ihs solution, add 1 mg of gallium acetylacetonate (C 15 H 21 GaO6), stir magnetically at room temperature for 12 h, centrifuge using acetone and ethanol, and dry in a vacuum drying oven. Under a nitrogen atmosphere, heat the above sample from room temperature to 250 °C at a rate of 2 °C min -1 , hold at this temperature for 2 h, and then cool to room temperature to obtain PdPtGa Ihs.

[0062] Example 7

[0063] The palladium-based nanocrystal material described in the present invention has a preparation method including the following steps:

[0064] (1) Preparation of Pd icosahedral nanocrystals: Dissolve 150 mg of polyvinylpyrrolidone (PVP, C6H9NO) n in 4 mL of diethylene glycol (C4H 10 O3), then stir magnetically in an oil bath and preheat at 120 °C for 20 min. Subsequently, add 2 mL of sodium tetrachloropalladate (Na2PdCl4, concentration 15.5 mg mL -1 ) with diethylene glycol as the solvent, take out the sample after stirring and reacting at 1500 rpm for 3 h, cool, and centrifuge using acetone and ethanol to obtain Pd icosahedral nanocrystals with a diameter of 15 nm, which are dispersed in 5 mL of deionized water for later use.

[0065] (2) Preparation of PdPt Ihs: Take the above Pd icosahedral nanocrystal solution, and simultaneously weigh 350 mg of PVP and 250 mg of ascorbic acid (AA), dissolve them in 20 mL of deionized water, and stir magnetically at 30 °C for 20 min. At the same time, dissolve 17.5 mg of potassium bromide (KBr) and 7.5 mg of potassium chloroplatinate (K2PtCl4) in 10 mL of deionized water, add them to the above mixed solution at one time, react at 30 °C for 12 h, collect by centrifugal washing with acetone and ethanol, and disperse in 10 mL of deionized water for later use.

[0066] (3) Preparation of PdPtGa Ihs: Take the above PdPt Ihs solution, add 1 mg of gallium acetylacetonate (C 15 H 21 GaO6), stir magnetically at room temperature for 12 h, centrifuge using acetone and ethanol, and dry in a vacuum drying oven. Under a nitrogen atmosphere, heat the above sample from room temperature to 300 °C at a rate of 0.5 °C min -1 , hold at this temperature for 2 h, and then cool to room temperature to obtain PdPtGa Ihs.

[0067] Example 8

[0068] The palladium-based nanocrystal material of the present invention has a preparation method including the following steps:

[0069] (1) Preparation of Pd icosahedral nanocrystals: Dissolve 150 mg of polyvinylpyrrolidone (PVP, C6H9NO) n in 4 mL of diethylene glycol (C4H 10 O3), then magnetically stir in an oil bath and preheat at 120 °C for 20 min. Subsequently, add 2 mL of sodium tetrachloropalladate (Na2PdCl4, concentration 15.5 mg mL -1 ) using diethylene glycol as the solvent. After stirring and reacting at 1500 rpm for 3 h, take out the sample, cool it, and centrifuge using acetone and ethanol to obtain Pd icosahedral nanocrystals with a diameter of 15 nm, which are dispersed in 5 mL of deionized water for standby.

[0070] (2) Preparation of PdPt Ihs: Take the above Pd icosahedral nanocrystal solution, and simultaneously weigh 350 mg of PVP and 250 mg of ascorbic acid (AA) and dissolve them in 20 mL of deionized water. Magnetically stir at 30 °C for 20 min. At the same time, dissolve 17.5 mg of potassium bromide (KBr) and 7.5 mg of potassium chloroplatinate (K2PtCl4) in 10 mL of deionized water, and add them to the above mixed solution at one time. React at 30 °C for 12 h, collect by centrifugal washing using acetone and ethanol, and disperse in 10 mL of deionized water for standby.

[0071] (3) Preparation of PdPtGa Ihs: Take the above PdPt Ihs solution, add 1 mg of gallium acetylacetonate (C 15 H 21 GaO6), magnetically stir at room temperature for 12 h, centrifuge using acetone and ethanol, and dry in a vacuum drying oven. Under a nitrogen atmosphere, heat-treat the above sample at a programmed heating rate of 5 °C min -1 to 300 °C and hold at this temperature for 2 h, then cool to room temperature to obtain PdPtGa Ihs.

[0072] Example 9

[0073] The palladium-based nanocrystal material of the present invention has a preparation method including the following steps:

[0074] (1) Preparation of Pd icosahedral nanocrystals: Dissolve 150 mg of polyvinylpyrrolidone (PVP, C6H9NO) n in 4 mL of diethylene glycol (C4H 10 O3), then magnetically stir in an oil bath and preheat at 120 °C for 20 min. Subsequently, add 2 mL of sodium tetrachloropalladate (Na2PdCl4, concentration 15.5 mg mL-1 ) After stirring the reaction at 1500 rpm for 3 h, the sample was taken out, cooled, and centrifuged with acetone and ethanol to obtain Pd icosahedral nanocrystals with a diameter of 15 nm, which were dispersed in 5 mL of deionized water for later use.

[0075] (2) Preparation of PdPt Ihs: Take the above Pd icosahedral nanocrystal solution. At the same time, weigh 350 mg of PVP and 250 mg of ascorbic acid (AA) and dissolve them in 20 mL of deionized water, and magnetically stir for 20 min at 30 °C. At the same time, dissolve 17.5 mg of potassium bromide (KBr) and 7.5 mg of potassium chloroplatinate (K2PtCl4) in 10 mL of deionized water, and add them to the above mixed solution at one time. React at 30 °C for 12 h, collect by centrifugal washing with acetone and ethanol, and disperse in 10 mL of deionized water for later use.

[0076] (3) Preparation of PdPtGa Ihs: Take the above PdPt Ihs solution, add 1 mg of gallium acetylacetonate (C 15 H 21 GaO6), magnetically stir at room temperature for 12 h, centrifuge with acetone and ethanol, and dry in a vacuum drying oven. Under a nitrogen atmosphere, heat-treat the above sample at a programmed heating rate of 2 °C min -1 to 300 °C and hold at this temperature for 5 h, then cool to room temperature to obtain PdPtGa Ihs.

[0077] Example 10

[0078] The preparation method of the palladium-based nanocrystal material described in the present invention includes the following steps:

[0079] (1) Preparation of Pd icosahedral nanocrystals: Dissolve 150 mg of polyvinylpyrrolidone (PVP, C6H9NO) n in 4 mL of diethylene glycol (C4H 10 O3), then magnetically stir in an oil bath and preheat at 120 °C for 20 min. Subsequently, add 2 mL of sodium tetrachloropalladate (Na2PdCl4, concentration 15.5 mg mL -1 ) using diethylene glycol as the solvent. After stirring the reaction at 1500 rpm for 3 h, the sample was taken out, cooled, and centrifuged with acetone and ethanol to obtain Pd icosahedral nanocrystals with a diameter of 15 nm, which were dispersed in 5 mL of deionized water for later use.

[0080] (2) Preparation of PdPt Ihs: Take the above Pd icosahedral nanocrystal solution. Meanwhile, weigh 350 mg of PVP and 250 mg of ascorbic acid (AA), dissolve them in 20 mL of deionized water, and magnetically stir for 20 min at 30 °C. Meanwhile, dissolve 17.5 mg of potassium bromide (KBr) and 7.5 mg of potassium chloroplatinate (K2PtCl4) in 10 mL of deionized water, and add them to the above mixed solution at one time. React at 30 °C for 12 h, collect by centrifugal washing with acetone and ethanol, and disperse in 10 mL of deionized water for standby.

[0081] (3) Preparation of PdPtGa Ihs: Take the above PdPt Ihs solution, add 1 mg of gallium acetylacetonate (C 15 H 21 GaO6), magnetically stir at room temperature for 12 h, centrifuge with acetone and ethanol, and dry in a vacuum drying oven. Under a nitrogen atmosphere, heat the above sample at a rate of 2 °C min -1 to 300 °C for heat treatment, hold at this temperature for 7 h, and then cool to room temperature to obtain PdPtGa Ihs.

[0082] Example 11

[0083] The preparation method of the palladium-based nanocrystal material described in the present invention includes the following steps:

[0084] (1) Preparation of Pd icosahedral nanocrystals: Dissolve 150 mg of polyvinylpyrrolidone (PVP, C6H9NO) n in 4 mL of diethylene glycol (C4H 10 O3), then magnetically stir in an oil bath and preheat at 120 °C for 20 min. Subsequently, add 2 mL of sodium tetrachloropalladate (Na2PdCl4, concentration 15.5 mg mL -1 ) with diethylene glycol as the solvent, take out the sample after stirring and reacting at 1500 rpm for 3 h, cool, and centrifuge with acetone and ethanol to obtain Pd icosahedral nanocrystals with a diameter of 15 nm, which are dispersed in 5 mL of deionized water for standby.

[0085] (2) Preparation of PdPt Ihs: Take the above Pd icosahedral nanocrystal solution. Meanwhile, weigh 350 mg of PVP and 250 mg of ascorbic acid (AA), dissolve them in 20 mL of deionized water, and magnetically stir for 20 min at 30 °C. Meanwhile, dissolve 17.5 mg of potassium bromide (KBr) and 7.5 mg of potassium chloroplatinate (K2PtCl4) in 10 mL of deionized water, and add them to the above mixed solution at one time. React at 30 °C for 12 h, collect by centrifugal washing with acetone and ethanol, and disperse in 10 mL of deionized water for standby.

[0086] (3) Preparation of PdPtGa Ihs: Take the above PdPt Ihs solution, add 1 mg of gallium acetylacetonate (C 15 H 21 GaO6), stir magnetically at room temperature for 12 h, centrifuge using acetone and ethanol, and dry in a vacuum drying oven. Under a nitrogen atmosphere, heat the above sample to 300 °C at a heating rate of 2 °C min -1 for heat treatment, hold at this temperature for 1 h, and then cool to room temperature to obtain PdPtGa Ihs.

[0087] Comparative Example 1

[0088] Based on Example 3, only perform steps (1) and (2), do not perform step (3), and keep the other conditions unchanged.

[0089] Comparative Example 2

[0090] Based on Example 3, keep the reaction temperature in step (1) at 140 °C and keep the other conditions unchanged.

[0091] Comparative Example 3

[0092] Based on Example 3, no potassium bromide is added in step (2), and the other conditions remain unchanged.

[0093] Structure Characterization

[0094] The PdPtGa Ihs prepared in Example 3 was physically characterized by means of HADDDF-STEM, HRTEM, mapping, XRD, XPS, etc.

[0095] From Figure 1 the large-area HRTEM images ( Figure 1 a) and HRTEM ( Figure 1 b), it can be seen that the PdPtGa Ihs nanocrystals prepared in Example 3 are uniformly dispersed, and the size of a single particle is 17.8 nm.

[0096] From Figure 2 the further magnified HRTEM images ( Figure 2 a and Figure 2 b), it can be seen that the PdPtGa Ihs nanocrystals prepared in Example 3 have clear and distinct twin grain boundaries, indicating that they have a deca-twinned structure. After measurement, the lattice spacing of the PdPtGa nanocrystals on the plane is 0.233 nm, corresponding to the (111) crystal plane of Pd, while the lattice spacing at the twin grain boundary is 0.227 nm, corresponding to the (100) crystal plane of Pt.

[0097] From Figure 3According to the mapping spectrum, the PdPtGa prepared in Example 3 has three components: Pd, Pt, and Ga.

[0098] From Figure 4 the XPS spectrum, it can be seen that Pd in PdPtGa Ihs prepared in Example 3 mainly exists in the zero-valent form, Pt mainly forms metal bonds with Pd, and part of Ga is oxidized.

[0099] From Figure 8 the TEM image, it can be seen that when the reaction temperature in step (1) is too high, the morphology of Pd nanocrystals is non-uniform and self-nucleation is relatively serious.

[0100] From Figure 9 the TEM image, it can be seen that when potassium bromide is no longer added in step (2), Pt cannot selectively grow on the vertices of Pd icosahedral crystals.

[0101] Performance test

[0102] The ethanol anodic oxidation catalytic activities of the palladium-based materials prepared in Example 3 and Comparative Example 1 and the commercial 20% Pd / C catalyst were tested.

[0103] Test method: 10 mg of catalyst powder was dispersed in 990 μL of a water / ethanol (v / v = 1:1) mixed solvent together with 10 μL of 5 wt% Nafion solution, and the mixed solution was ultrasonically treated for 10 minutes. Then, 5 μL of the catalyst ink was loaded onto a glassy carbon electrode (diameter = 3 mm). The ethanol anodic oxidation electrochemical test was carried out in a standard three-electrode electrolytic cell on an electrochemical workstation (CHI 660E). A saturated calomel electrode (SCE) was used as the reference electrode for acidic (0.5 M H2SO4 + 1 M C2H5OH) and basic (1 M KOH + 1 M C2H5OH) electrochemical measurements. A graphite plate was used as the counter electrode in all measurements. The electrolyte solution was saturated with high-purity N2 gas flow for 30 minutes before the test to exclude the interference of other gases. Linear sweep voltammetry (LSV) was used to test the polarization curve of the material (scan rate 5 mV s -1 ). The test results are as Figure 5 and 6 shown.

[0104] Figure 5 are the CV curves (5a) and mass-specific activities (5b) of the catalytic materials of Example 3 and Comparative Example 1 and the commercial 20% Pd / C catalyst in 0.5 M H2SO4, and the CV curves (5c) and mass-specific activities (5d) in 0.5 M H2SO4 and 1.0 M ethanol.

[0105] Figure 6CV curves of the catalytic materials prepared in Example 3 and Comparative Example 1 and the commercial 20% Pd / C catalyst in 1.0 M KOH (6a) and CV curves in 1.0 M KOH and 1.0 M ethanol.

[0106] It can be obtained from Figure 5 that the mass specific activities of the catalytic materials prepared in Example 3 and Comparative Example 1 and the commercial 20% Pd / C catalyst obtained from the CV diagrams in 0.5 M H2SO4 are 123.81 m 2 g -1 , 62.72 m 2 g -1 and 35.43 m 2 g -1 respectively; and the mass specific activities obtained from the CV diagrams in 0.5 M H2SO4 and 1.0 M ethanol solution are 298.58 m 2 g -1 , 111.14 m 2 g -1 and 107.85 m 2 g -1 respectively. It can be seen that under the conditions of Example 3, the synthesized sample has the best performance.

[0107] It can be obtained from Figure 6 that the catalytic materials prepared in Example 3 and Comparative Example 1 and the commercial 20% Pd / C catalyst also have certain catalytic activities for ethanol oxidation in an alkaline environment. Thus, it can be proved that the sample has good EOR catalytic activity in a wide pH range.

[0108] The stability of the palladium-based material prepared in Example 3 was further tested, and the test results are as Figure 7 shown.

[0109] It can be obtained from Figure 7 that after 2000 cycles of accelerated durability stability test, the catalytic activity and morphology of Rh2P Dhs prepared in Example 3 for ethanol oxidation remain almost unchanged, indicating its excellent electrochemical durability.

[0110] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0111] It should be noted that the above content only illustrates the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a palladium-based material with multiple twins, characterized in that, It includes the following steps: (1) Dissolve polyvinylpyrrolidone and sodium tetrachloropalladate in diethylene glycol and conduct a solvothermal reaction to obtain black Pd icosahedral nanocrystals with a multiple twin structure; (2) Dissolve the black Pd icosahedral nanocrystals, polyvinylpyrrolidone, ascorbic acid, potassium bromide, and potassium chloroplatinate in water and react to obtain Pd-based nanocrystals with selectively grown Pt; (3) Add gallium acetylacetonate to the Pd-based nanocrystals with selectively grown Pt, react at room temperature, centrifuge and dry, and then calcine and reduce in an inert atmosphere to obtain a Ga-PdPt nanocrystal material.

2. The preparation method of a palladium-based material with multiple twins according to claim 1, characterized in that, In step (1), the mass-volume ratio of polyvinylpyrrolidone to diethylene glycol is 25-30:1; the mass-volume ratio of sodium tetrachloropalladate to diethylene glycol is 31:

6.

3. The preparation method of a palladium-based material with multiple twins according to claim 1, characterized in that, In step (1), the temperature of the solvothermal reaction is 120-130 °C and the time is 3-4 h.

4. The preparation method of a palladium-based material with multiple twins according to claim 1, characterized in that In step (2), the mass ratio of sodium tetrachloropalladate, polyvinylpyrrolidone, ascorbic acid, potassium bromide, and potassium chloroplatinate in step (1) is 1:11-11.5:7-9:0.5-0.6:0.08-0.

25.

5. The preparation method of a palladium-based material with multiple twins according to claim 1, characterized in that, In step (3), the mass ratio of gallium acetylacetonate to sodium tetrachloropalladate in step (1) is 1:30-35.

6. The preparation method of a palladium-based material with multiple twins according to claim 1, characterized in that, In step (3), the specific conditions for calcination reduction are as follows: heating up by 0.5 to 5 °C per minute -1 to 250 to 400 °C for heat treatment with a holding time of 1 to 7 hours at this temperature.

7. A palladium-based material with multiple twins prepared by the preparation method described in any one of claims 1-6.

8. A palladium-based material with multiple twins according to claim 7, characterized in that, The palladium-based material is a Ga-PdPt nanocrystal material supported on activated carbon, and the Ga-PdPt nanocrystal material has an icosahedral structure.

9. An application of the palladium-based material with multiple twins described in claim 7 in an ethanol oxidation reaction.

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