A palladium-gold solid solution, a preparation method thereof, and applications thereof

Abstract

The present invention provides a method for preparing a palladium-gold solid solution, comprising the following steps: S1) Mixing a palladium salt and a gold salt in water to obtain a first mixed solution; mixing an organic monomer and water to obtain a second mixed solution; S2) Adding an organic buffer to the first mixed solution, adjusting the pH value to alkaline, then adding the second mixed solution, and continuously stirring to obtain a precursor; S3) Annealing the precursor in a protective atmosphere to obtain a palladium-gold solid solution. Compared with the prior art, the present invention uses an organic monomer to polymerize and coat palladium-gold ion clusters under alkaline conditions, and a palladium-gold solid solution can be obtained after annealing treatment, providing the uniformity of the gold phase structure distribution in the solid solution. As a catalyst, it has high electrocatalytic oxygen reduction activity, and this preparation method is safe and easy to implement, without generating additional toxic by-products, and the required equipment is simple. It is a method for large-scale preparation of palladium-gold solid solution catalysts.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid solution alloys, and particularly relates to a palladium-gold solid solution, a preparation method thereof, and an application thereof. Background Art

[0002] A large number of research results have shown that the coordination configuration and electronic structure of catalysts are the key factors determining their catalytic activity. In recent years, strategies such as alloying, defect construction, interface optimization, and ligand modification have been successively reported to regulate the microstructure of catalysts. Among them, the alloying strategy has received extensive attention because it can effectively regulate the energy band structure of active species, the adsorption behavior of intermediates, and the surface electron concentration. Solid solution alloys can continuously adjust the coordination environment and electron distribution of metal sites by changing the element ratio, which is beneficial to designing an appropriate catalyst microenvironment according to different reaction requirements. However, affected by the surface energy of metals, solid solution alloys often undergo metal segregation during synthesis and service, forming a core-shell structure or an atomic island distribution state, which is one of the important reasons for catalyst deactivation. Therefore, it is crucial to develop a reasonable synthesis strategy to obtain a solid solution catalyst with continuously adjustable components. Summary of the Invention

[0003] In view of this, the technical problem to be solved by the present invention is to provide a palladium-gold solid solution with a uniform metallographic structure distribution, a preparation method thereof, and an application thereof.

[0004] The present invention provides a preparation method of a palladium-gold solid solution, comprising the following steps:

[0005] S1) Mixing a palladium salt and a gold salt in water to obtain a first mixed solution;

[0006] Mixing an organic monomer and water to obtain a second mixed solution;

[0007] S2) Adding an organic buffer to the first mixed solution, adjusting the pH value to alkaline, then adding the second mixed solution, and continuously stirring to obtain a precursor;

[0008] S3) Annealing the precursor in a protective atmosphere to obtain a palladium-gold solid solution.

[0009] Preferably, the palladium salt is selected from chloropalladates; the gold salt is selected from chloroaurates; the molar ratio of the palladium salt to the gold salt is (0.33 - 3):1.

[0010] Preferably, the palladium salt is selected from K2PdCl4; the gold salt is selected from NaAuCl4; the molar ratio of the palladium salt to the gold salt is (0.33 - 3):1.

[0011] Preferably, the concentration of the palladium salt and the gold salt in the first mixed solution are each independently 0.1 to 1.4 mmol / L; the concentration of the organic monomer in the second mixed solution is 20 to 30 mmol / L.

[0012] Preferably, the volume ratio of the first mixed solution to the second mixed solution is 1:(0.8 to 1.5).

[0013] Preferably, the organic monomer is dopamine hydrochloride; the organic buffer is tris(hydroxymethyl)aminomethane; the concentration of the organic buffer in the first mixed solution added with the organic buffer is 10 to 20 mmol / L.

[0014] Preferably, the continuous stirring time in the step S2) is 12 to 24 h.

[0015] Preferably, the temperature of the annealing treatment is 500°C to 900°C; the heating rate of the annealing treatment is 5 to 10°C / min; the heat preservation time of the annealing treatment is 1 to 2 h.

[0016] The present invention also provides a palladium-gold solid solution prepared by the above preparation method.

[0017] The present invention also provides an application of the palladium-gold solid solution prepared by the above preparation method as a catalyst for an electrocatalytic reduction reaction.

[0018] The present invention provides a method for preparing a palladium-gold solid solution, comprising the following steps: S1) mixing a palladium salt and a gold salt in water to obtain a first mixed solution; mixing an organic monomer and water to obtain a second mixed solution; S2) adding an organic buffer to the first mixed solution, adjusting the pH value to alkaline, then adding the second mixed solution, and continuously stirring to obtain a precursor; S3) annealing the precursor in a protective atmosphere to obtain a palladium-gold solid solution. Compared with the prior art, the present invention uses an organic monomer to polymerize and coat palladium-gold ion clusters under alkaline conditions, and a palladium-gold solid solution can be obtained after annealing treatment, providing the uniformity of the gold phase structure distribution in the solid solution, having high electrocatalytic oxygen reduction activity as a catalyst, and the preparation method is safe and easy to implement, without generating additional toxic by-products, and the required equipment is simple, which is a method for large-scale preparation of palladium-gold solid solution catalysts. Description of the Drawings

[0019] Figure 1 It is the X-ray diffraction pattern of the palladium-gold solid solution catalysts prepared in Examples 1 to 5 of the present invention and the single-metal catalysts obtained in Comparative Examples 1 to 2;

[0020] Figure 2 It is the transmission electron microscope image of the palladium-gold solid solution catalysts prepared in Examples 1 to 5 of the present invention and the single-metal catalysts obtained in Comparative Examples 1 to 2;

[0021] Figure 3 It is the linear scanning result diagram of energy dispersive X-ray spectroscopy of the palladium-gold solid solution catalyst prepared in Examples 1-5 of the present invention;

[0022] Figure 4 It is the linear sweep voltammogram measured for the palladium-gold solid solution catalyst prepared in Examples 1-5 of the present invention, the single-metal catalysts obtained in Comparative Examples 1-2, and the commercial 20 wt% Pt / C catalyst in 0.1 M KOH with a scan rate of 10 mV / s and a rotation speed of 1600 rpm. Detailed implementation manners

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] The present invention provides a method for preparing a palladium-gold solid solution, comprising the following steps: S1) Mix a palladium salt and a gold salt in water to obtain a first mixed solution; mix an organic monomer and water to obtain a second mixed solution; S2) Add an organic buffer to the first mixed solution, adjust the pH value to alkaline, then add the second mixed solution, and continuously stir to obtain a precursor; S3) Anneal the precursor in a protective atmosphere to obtain a palladium-gold solid solution.

[0025] The present invention uses an organic monomer to polymerize and coat palladium-gold ion clusters under alkaline conditions, and a palladium-gold solid solution can be obtained after annealing treatment, which provides the uniformity of the gold phase structure distribution in the solid solution. As a catalyst, it has high electrocatalytic oxygen reduction activity, and this preparation method is safe and easy to implement, without generating additional toxic by-products, and the required equipment is simple. It is a method that can prepare palladium-gold solid solution catalysts on a large scale.

[0026] Among them, the present invention does not have special restrictions on the sources of all raw materials, and they can be commercially available.

[0027] Mix a palladium salt and a gold salt in water to obtain a first mixed solution; the palladium salt is preferably a chloropalladate, more preferably K2PdCl4; the gold salt is preferably a chloroaurate, more preferably NaAuCl4; the molar ratio of the palladium salt to the gold salt is preferably (0.33 - 3):1; in the examples provided by the present invention, the molar ratio of the palladium salt to the gold salt is specifically 3:1, 2:1, 1:1, 1:2 or 1:3; the concentration of the palladium salt in the first mixed solution is preferably 0.1 - 1.4 mmol / L, more preferably 0.2 - 1.4 mmol / L, and still more preferably 0.34 - 1.06 mmol / L; the concentration of the gold salt in the first mixed solution is preferably 0.1 - 1.4 mmol / L, more preferably 0.2 - 1.4 mmol / L, and still more preferably 0.34 - 1.06 mmol / L.

[0028] Mix an organic monomer and water to obtain a second mixed solution; the organic monomer is preferably dopamine hydrochloride; the concentration of the organic monomer in the second mixed solution is preferably 20 - 30 mmol / L, more preferably 20 - 25 mmol / L, and still more preferably 21 mmol / L.

[0029] Add an organic buffer to the first mixed solution, adjust the pH value to alkaline, then add the second mixed solution, and continuously stir to obtain a precursor; the organic buffer is preferably tris(hydroxymethyl)aminomethane; the concentration of the organic buffer in the first mixed solution after adding the organic buffer is preferably 10 - 20 mmol / L, more preferably 12 - 15 mmol / L, and still more preferably 13 mmol / L; the volume ratio of the first mixed solution to the second mixed solution is preferably 1:(0.8 - 1.5), more preferably 1:(0.8 - 1.2), and still more preferably 1:1; the second mixed solution is added in the form of drops; the duration of continuous stirring is preferably 12 - 24 h, more preferably 15 - 24 h, and still more preferably 20 - 24 h; through continuous stirring, the organic monomer can polymerize under alkaline conditions and coat the palladium and gold ion clusters. When the organic monomer is dopamine hydrochloride, polydopamine is formed by polymerization during continuous stirring, and in the specific process, the palladium salt and the gold salt are mixed to form solid solution nanoparticles and are coated in the polydopamine; after the stirring is completed, it is preferably centrifuged and freeze-dried to obtain the precursor.

[0030] Anneal the precursor in a protective atmosphere to obtain a palladium-gold solid solution; the protective atmosphere can be any protective atmosphere well-known to those skilled in the art without special limitations. In the present invention, nitrogen and / or argon is preferably used, and argon is more preferably used; the temperature of the annealing treatment is preferably 500°C to 900°C, more preferably 700°C to 900°C, and still more preferably 800°C to 900°C; the heating rate of the annealing treatment is preferably 5 to 10°C / min, more preferably 5 to 6°C / min; the holding time of the annealing treatment is preferably 1 to 2 h; High-temperature annealing can fully pyrolyze polydopamine to produce defective carbon carriers, and at the same time expose the solid solution nanoparticles that can serve as active sites, thereby promoting the catalytic reaction process.

[0031] The preparation method provided by the present invention can continuously adjust the coordination environment and electron distribution of the solid solution catalyst by changing the element ratio, which is beneficial to designing the catalyst microenvironment and adjusting the intermediate adsorption behavior according to specific reaction requirements. In addition, this preparation method is safe and easy to implement, does not produce additional toxic by-products, and requires simple equipment, which is a method for large-scale preparation of palladium-gold solid solution catalysts.

[0032] The present invention also provides a palladium-gold solid solution prepared by the above preparation method.

[0033] The present invention also provides an application of the palladium-gold solid solution prepared by the above preparation method as a catalyst for electrocatalytic reduction reaction.

[0034] In order to further illustrate the present invention, the following examples are used to describe in detail a palladium-gold solid solution, its preparation method and application provided by the present invention.

[0035] All reagents used in the following examples are commercially available.

[0036] Example 1

[0037] 1) Weigh 0.053 mmol of K2PdCl4 and 0.017 mmol of NaAuCl4·2H2O, add 50 mL of deionized water, and stir to dissolve to obtain a first mixed solution; then add 80 mg of tris(hydroxymethyl)aminomethane to adjust the pH of the first mixed solution to weakly alkaline;

[0038] 2) Weigh 200 mg of hydrochloric acid dopamine, add 50 mL of deionized water, and stir to dissolve to obtain a second mixed solution;

[0039] 3) Slowly drip the second mixed solution into the first mixed solution, continuously stir for 24 hours to fully polymerize the hydrochloric acid dopamine, centrifuge to collect the precipitate, wash it several times with deionized water, and freeze-dry overnight to obtain a powder precursor;

[0040] 4) Place a 30 mg precursor sample into a porcelain boat, then put the porcelain boat into a tube furnace, and use an argon gas flow to remove the air in the furnace; then heat it to 900 °C at a heating rate of 5 °C / min under an argon atmosphere, hold for 2 hours, and finally cool to room temperature to obtain a palladium-gold solid solution catalyst with a certain proportion.

[0041] Analyze the palladium-gold solid solution catalyst obtained in Example 1 using X-rays to obtain its X-ray diffraction pattern, as Figure 1 shown. From Figure 1 it can be seen that the diffraction peak position in Example 1 is between the standard peak positions of Pd (PDF#46-1043) and Au (PDF#04-0784), and no new signals appear, proving the successful miscibility of Pd and Au. The molar ratio of Pd and Au calculated from the inductively coupled plasma atomic emission spectrometry results is 77:23, which is close to the ratio of palladium salt and gold salt of 3:1 in the reactants.

[0042] Analyze the palladium-gold solid solution catalyst obtained in Example 1 using a transmission electron microscope to obtain its transmission electron microscope image, as Figure 2 shown. From Figure 2 it can be seen that the palladium-gold solid solution in Example 1 exists in the form of nanoparticles.

[0043] Analyze the palladium-gold solid solution catalyst obtained in Example 1 using energy-dispersive X-rays to obtain the linear scanning results of its energy-dispersive X-ray spectrum, as Figure 3 shown. From Figure 3 it can be seen that Pd and Au in Example 1 are synchronously distributed, and no metal segregation or core-shell structure appears, once again proving the successful synthesis of the palladium-gold solid solution.

[0044] Example 2

[0045] In step 1), the amount of substance of K2PdCl4 is 0.047 mmol, and that of NaAuCl4·2H2O is 0.023 mmol. The rest is the same as in Example 1 to prepare a palladium-gold solid solution catalyst with a certain proportion.

[0046] Analyze the palladium-gold solid solution catalyst obtained in Example 2 using X-rays to obtain its X-ray diffraction pattern, as Figure 1 shown. From Figure 1 it can be seen that the diffraction peak position in Example 2 is between the standard peak positions of Pd (PDF#46-1043) and Au (PDF#04-0784), and no new signals appear, proving the successful miscibility of Pd and Au. The molar ratio of Pd and Au calculated from the inductively coupled plasma atomic emission spectrometry results is 66:34, which is close to the ratio of palladium salt and gold salt of 2:1 in the reactants.

[0047] The palladium-gold solid solution catalyst obtained in Example 2 was analyzed using a transmission electron microscope to obtain its transmission electron microscope image, as shown in Figure 2 . It can be seen from Figure 2 that the palladium-gold solid solution in Example 2 exists in the form of nanoparticles.

[0048] The palladium-gold solid solution catalyst obtained in Example 2 was analyzed using energy-dispersive X-ray to obtain the linear scanning result of its energy-dispersive X-ray spectrum, as shown in Figure 3 . It can be seen from Figure 3 that Pd and Au in Example 2 are synchronously distributed, and no metal segregation or core-shell structure appears, further proving the successful synthesis of the palladium-gold solid solution.

[0049] Example 3

[0050] In step 1), the amount of substance of K2PdCl4 was 0.035 mmol, and that of NaAuCl4·2H2O was 0.035 mmol. The rest was the same as in Example 1, and a palladium-gold solid solution catalyst with a certain ratio was prepared.

[0051] The palladium-gold solid solution catalyst obtained in Example 3 was analyzed using X-ray to obtain its X-ray diffraction pattern, as shown in Figure 1 . The diffraction peak position in Example 3 is between the standard peak positions of Pd (PDF#46-1043) and Au (PDF#04-0784), and no new signal appears, proving the successful miscibility of Pd and Au. The molar ratio of Pd and Au calculated from the inductively coupled plasma atomic emission spectrometry results is 55:45, close to the ratio of palladium salt and gold salt 1:1 in the reactants.

[0052] The palladium-gold solid solution catalyst obtained in Example 3 was analyzed using a transmission electron microscope to obtain its transmission electron microscope image, as shown in Figure 2 . It can be seen from Figure 2 that the palladium-gold solid solution in Example 3 exists in the form of nanoparticles.

[0053] The palladium-gold solid solution catalyst obtained in Example 3 was analyzed using energy-dispersive X-ray to obtain the linear scanning result of its energy-dispersive X-ray spectrum, as shown in Figure 3 . It can be seen from Figure 3 that Pd and Au in Example 3 are synchronously distributed, and no metal segregation or core-shell structure appears, further proving the successful synthesis of the palladium-gold solid solution.

[0054] Example 4

[0055] In step 1), the amount of substance of K2PdCl4 was 0.023 mmol, and that of NaAuCl4·2H2O was 0.047 mmol. The rest was the same as in Example 1, and a palladium-gold solid solution catalyst with a certain ratio was prepared.

[0056] The palladium-gold solid solution catalyst obtained in Example 4 was analyzed by X-ray to obtain its X-ray diffraction pattern, as Figure 1 shown. It can be seen from Figure 1 that the diffraction peak position of Example 4 was between the standard peak positions of Pd (PDF#46-1043) and Au (PDF#04-0784), and no new signal appeared, proving the successful miscibility of Pd and Au. The molar ratio of Pd and Au calculated from the inductively coupled plasma atomic emission spectrometry results was 32:68, close to the ratio of palladium salt and gold salt 1:2 in the reactants.

[0057] The palladium-gold solid solution catalyst obtained in Example 4 was analyzed by transmission electron microscope to obtain its transmission electron microscope image, as Figure 2 shown. It can be seen from Figure 2 that the palladium-gold solid solution in Example 4 existed in the form of nanoparticles.

[0058] The palladium-gold solid solution catalyst obtained in Example 4 was analyzed by energy-dispersive X-ray to obtain the linear scanning result of its energy-dispersive X-ray spectrum, as Figure 3 shown. It can be seen from Figure 3 that Pd and Au in Example 4 were synchronously distributed, and no metal segregation or core-shell structure appeared, further proving the successful synthesis of the palladium-gold solid solution.

[0059] Example 5

[0060] In step 1), the amount of substance of K2PdCl4 was 0.017 mmol, and that of NaAuCl4·2H2O was 0.053 mmol. The rest was the same as in Example 1, and a palladium-gold solid solution catalyst with a certain ratio was prepared.

[0061] The palladium-gold solid solution catalyst obtained in Example 5 was analyzed by X-ray to obtain its X-ray diffraction pattern, as Figure 1 shown. It can be seen from Figure 1 that the diffraction peak position of Example 5 was between the standard peak positions of Pd (PDF#46-1043) and Au (PDF#04-0784), and no new signal appeared, proving the successful miscibility of Pd and Au. The molar ratio of Pd and Au calculated from the inductively coupled plasma atomic emission spectrometry results was 26:74, close to the ratio of palladium salt and gold salt 1:3 in the reactants.

[0062] The palladium-gold solid solution catalyst obtained in Example 5 was analyzed using a transmission electron microscope, and its transmission electron microscope image was obtained, as shown in Figure 2 shown. From Figure 2 it can be seen that the palladium-gold solid solution in Example 5 exists in the form of nanoparticles.

[0063] The palladium-gold solid solution catalyst obtained in Example 5 was analyzed using energy-dispersive X-ray, and the linear scanning result of its energy-dispersive X-ray spectrum was obtained, as shown in Figure 3 shown. From Figure 3 it can be seen that Pd and Au in Example 5 are synchronously distributed, and no metal segregation or core-shell structure appears, further proving the successful synthesis of the palladium-gold solid solution.

[0064] Comparative Example 1

[0065] In step 1), the amount of substance of K2PdCl4 was 0.07 mmol, and NaAuCl4·2H2O was not added. The rest was the same as in Example 1, and a palladium single-metal catalyst was prepared.

[0066] The palladium single-metal catalyst obtained in Comparative Example 1 was analyzed using X-ray, and its X-ray diffraction pattern was obtained, as shown in Figure 1 shown. From Figure 1 it can be seen that the diffraction peak position in Comparative Example 1 conforms to the standard peak position of Pd (PDF#46-1043), and no new signal appears, proving the successful synthesis of the palladium single-metal catalyst.

[0067] The palladium single-metal catalyst obtained in Comparative Example 1 was analyzed using a transmission electron microscope, and its transmission electron microscope image was obtained, as shown in Figure 2 shown. From Figure 2 it can be seen that the palladium single-metal catalyst in Comparative Example 1 exists in the form of nanoparticles.

[0068] Comparative Example 2

[0069] In step 1), K2PdCl4 was not added, and the amount of substance of NaAuCl4·2H2O was 0.07 mmol. The rest was the same as in Example 1, and a gold single-metal catalyst was prepared.

[0070] The gold single-metal catalyst obtained in Comparative Example 2 was analyzed using X-ray, and its X-ray diffraction pattern was obtained, as shown in Figure 1 shown. From Figure 1 it can be seen that the diffraction peak position in Comparative Example 2 conforms to the standard peak position of Au (PDF#04-0784), and no new signal appears, proving the successful synthesis of the gold single-metal catalyst.

[0071] The gold single-metal catalyst obtained in Comparative Example 2 was analyzed using a transmission electron microscope, and its transmission electron microscope image was obtained, as shown inFigure 2 As shown. By Figure 2 It can be seen that the gold monometallic catalyst in Comparative Example 2 exists in the form of nanoparticles.

[0072] Example 6

[0073] The electrocatalytic oxygen reduction reaction activities of Examples 1-5, Comparative Examples 1-2 and commercial 20 wt% Pt / C catalyst were evaluated in 0.1 M KOH. The specific steps and results are as follows:

[0074] All electrochemical data tests were carried out in a standard three-electrode system. A Hg / HgO electrode calibrated by a standard hydrogen electrode was used as the reference electrode, a graphite carbon rod was used as the counter electrode, and a 5 mm disk electrode loaded with the catalyst was used as the working electrode. For the working electrode, 4 mg of the solid solution catalysts prepared in Examples 1-5, the monometallic catalysts prepared in Comparative Examples 1-2 and the commercial 20 wt% Pt / C catalyst samples were respectively added to a mixed solution composed of 550 μL of deionized water, 250 μL of isopropanol and 200 μL of 0.5% perfluorosulfonic acid type polymer aqueous solution (Nafion aqueous solution), and ultrasonicated for 1 hour to disperse evenly. 7.5 μL of each of the above suspensions was taken with a pipette and dropped on the 5 mm disk electrode, dried at room temperature, and then the disk electrode was installed on a rotator as the working electrode.

[0075] Figure 4 Are the linear sweep voltammograms measured for Examples 1-5, Comparative Examples 1-2 and commercial 20 wt% Pt / C catalyst in 0.1 M KOH with a controlled scan rate of 10 mV / s and a rotation speed of 1600 rpm. As Figure 4 shown, the half-wave potentials of the PdAu solid solution catalysts prepared by Examples 1-5 are 0.84 V, 0.85 V, 0.88 V, 0.84 V and 0.76 V respectively; the half-wave potentials of the monometallic catalysts prepared by Comparative Examples 1-2 are 0.83 V and 0.75 V respectively; the half-wave potential of the commercial 20 wt% Pt / C catalyst is 0.85 V; it can be seen that the solid solution catalyst with a Pd:Au molar ratio of 55:45 prepared by Example 3 has the highest half-wave potential, exceeding that of the commercial 20 wt% Pt / C catalyst and the monometallic catalysts. The results show that the alloying strategy can optimize the reaction activity of the catalyst, making the performance of the bimetallic solid solution alloy catalyst much higher than that of the monometallic catalyst and the commercial catalyst.

[0076] From the above Examples 1-6 and Comparative Examples 1-2, it can be seen that the palladium-gold solid solution catalyst prepared by the present invention has the characteristics of high electrocatalytic oxygen reduction activity, and the half-wave potential is better than that of the commercial 20 wt% Pt / C catalyst.

[0077] The palladium-gold solid solution catalysts synthesized in Examples 1 to 5 further prove that the preparation method of the present invention has universality in the synthesis of solid solution catalysts with continuously adjustable synthesis ratios. Obvious changes or variations derived therefrom are still within the protection scope of the preparation method of the present invention.

Claims

1. A method for preparing a palladium-gold solid solution, characterized in that, It includes the following steps: S1) Mix a palladium salt and a gold salt in water to obtain a first mixed solution; Mix an organic monomer and water to obtain a second mixed solution; the organic monomer is dopamine hydrochloride; S2) Add an organic buffer to the first mixed solution, adjust the pH value to alkaline, then add the second mixed solution, and continuously stir to obtain a precursor; S3) Anneal the precursor in a protective atmosphere to obtain a palladium-gold solid solution.

2. The preparation method according to claim 1, characterized in that, The palladium salt is selected from chloropalladates; the gold salt is selected from chloroaurates; the molar ratio of the palladium salt to the gold salt is (0.33 - 3):

1.

3. The preparation method according to claim 1, wherein The palladium salt is selected from K2PdCl4; the gold salt is selected from NaAuCl4; the molar ratio of the palladium salt to the gold salt is (0.33 - 3):

1.

4. The preparation method according to claim 1, wherein The concentration of the palladium salt and the gold salt in the first mixed solution are each independently 0.1 - 1.4 mmol / L; the concentration of the organic monomer in the second mixed solution is 20 - 30 mmol / L.

5. The preparation method according to claim 4, characterized in that, The volume ratio of the first mixed solution to the second mixed solution is 1:(0.8 - 1.5).

6. The preparation method according to claim 1, characterized in that, The organic buffer is tris(hydroxymethyl)aminomethane; the concentration of the organic buffer in the first mixed solution after adding the organic buffer is 10 - 20 mmol / L.

7. The preparation method according to claim 1, characterized in that, The continuous stirring time in step S2) is 12 - 24 h.

8. The preparation method according to claim 1, wherein The temperature of the annealing treatment is 500°C - 900°C; the heating rate of the annealing treatment is 5 - 10°C / min; the holding time of the annealing treatment is 1 - 2 h.

9. The palladium-gold solid solution prepared by the preparation method according to any one of claims 1 - 8.

10. The application of the palladium-gold solid solution prepared by the preparation method according to any one of claims 1 - 8 as a catalyst for electrocatalytic reduction reaction.

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