Nano-porous palladium-silver alloy self-supporting electrode and preparation method and application thereof

Abstract

The invention discloses a nano-porous palladium-silver alloy self-supporting electrode and a preparation method and application thereof.The preparation method comprises the following steps that (1) palladium, silver and metal particles prone to acid and alkali corrosion are mixed, then the mixture is placed in a smelting furnace to be smelted in an inert atmosphere, and then an alloy ingot is obtained after casting and cooling; (2) cutting the alloy ingot into alloy sheets; and (3) soaking the alloy sheet in an acid solution or an alkali solution for corrosion, taking out the alloy sheet after corrosion, and then cleaning and drying the alloy sheet to obtain the nano-porous palladium-silver alloy self-supporting electrode. According to the invention, the palladium-silver alloy with a three-dimensional bicontinuous nano-porous structure is constructed by utilizing a simple and feasible smelting-etching technology, the palladium-silver alloy is used as a self-supporting electrode for electro-catalytic phenol hydrogenation reaction and has excellent partial hydrogenation activity, selectivity and cycling stability of phenol, the conversion rate of phenol is 91.2%, and the selectivity of cyclohexanone is 98.9%.

Description

Technical Field

[0001] The present invention relates to the field of electrocatalysis technology, and in particular to a nanoporous palladium-silver alloy self-supporting electrode and a preparation method and application thereof. Background Art

[0002] Cyclohexanone is an important organic chemical raw material, mainly used in the manufacture of nylon 6 fiber, resin, plasticizer, etc. The preparation methods of cyclohexanone include cyclohexanol oxidation, phenol hydrogenation and cyclohexene oxidation. Compared with other preparation methods, phenol hydrogenation directly starts from phenol, reduces the intermediate steps, has a simple production process and is environmentally friendly, and has become the main method for preparing cyclohexanone. Traditionally, phenol hydrogenation to cyclohexanone mainly relies on thermal catalytic process. Although this method can achieve high conversion rate and selectivity, its operating conditions are harsh and often require high temperature (usually more than 150 °C) and high-pressure hydrogen (usually greater than 1 MPa), which not only increases production costs, but also brings safety hazards, especially when handling flammable and explosive hydrogen.

[0003] In this context, electrocatalytic hydrogenation has attracted much attention because it can efficiently convert biomass and its derivatives into valuable chemicals under relatively mild conditions. Electrocatalytic phenol hydrogenation to produce cyclohexanone can not only reduce energy consumption and greenhouse gas emissions, but also achieve more precise product control. However, in practical applications, the technology of electrocatalytic phenol hydrogenation to produce cyclohexanone still faces many challenges, the main difficulties are as follows: (1) Most existing electrocatalysts are based on single metal elements, such as precious metals such as platinum and palladium. Although these materials have certain activity, their intrinsic activity is insufficient, resulting in a low reaction rate.

[0004] (2) The catalyst has low selectivity for the target product cyclohexanone and is prone to produce by-products such as cyclohexanol, cyclohexane or incompletely hydrogenated intermediates, which further affects the purity and yield of the product.

[0005] (3) Traditional electrocatalysts mostly use two-dimensional or three-dimensional carriers. The number of active sites provided on the surface of these carriers is limited and unevenly distributed, which limits the reaction efficiency. In particular, for supported metal nanoparticle catalysts, they are prone to agglomeration during use, resulting in a decrease in effective specific surface area and active sites, thereby reducing catalytic performance. In addition, nanoparticles may fall off the surface of the carrier, causing the catalyst to deactivate, and are difficult to recycle and reuse, which increases the difficulty in practical applications.

[0006] Therefore, there is an urgent need for an electrocatalyst with high activity, high selectivity, high conductivity and high stability to realize the green, mild and efficient hydrogenation of phenol to cyclohexanone. Summary of the invention

[0007] The purpose of the present invention is to provide a nanoporous palladium-silver alloy self-supporting electrode and its preparation method and application, so as to solve the problems of low selectivity of the target product of the above-mentioned electrocatalyst, easy agglomeration and slow reaction rate.

[0008] To achieve the above object, the first aspect of the present invention provides a method for preparing a nanoporous palladium-silver alloy self-supporting electrode, comprising the following steps: (1) palladium, silver and metal particles susceptible to acid and alkali corrosion are mixed, then placed in a smelting furnace for smelting under an inert atmosphere, and then cast and cooled to obtain an alloy ingot; (2) Cutting the alloy ingot into alloy sheets; (3) The alloy sheet is immersed in an acid solution or an alkaline solution for corrosion, and the alloy sheet is taken out after corrosion, and then cleaned and dried to obtain a nanoporous palladium-silver alloy self-supporting electrode.

[0009] At present, the electrocatalyst components used in the preparation of cyclohexanone by hydrogenation of phenol are relatively simple, the intrinsic activity of single metal elements is insufficient, the selectivity for characteristic products is poor, and the limited active sites of low-dimensional materials cannot improve the yield of products. At the same time, there are structural defects, and supported metal nanoparticles are mostly used, which are prone to agglomeration and shedding during the electrocatalytic process, affecting the stability of the electrocatalyst. In view of this problem, the present invention prepares an alloy as an electrocatalyst. First, the alloy can show higher activity than a single metal, and the two or more elements in the alloy can produce synergistic effects, change the electronic structure, and thus improve the catalytic performance; secondly, the alloy catalyst is usually more stable than pure metals, which can prevent metal particles from agglomerating at high temperatures or reaction conditions, and keep the active sites of the catalyst basically unchanged.

[0010] Preferably, in step (1), the atomic ratio between palladium and metal particles susceptible to acid-base corrosion is selected according to the palladium-metal alloy phase diagram, and the atomic ratio of palladium to metal near the palladium-metal eutectic point is selected; the atomic ratio between palladium and silver is selected according to the palladium-silver alloy phase diagram, and the atomic ratio of palladium to silver in the palladium-silver mutual solubility region is selected.

[0011] The present invention continues to study and find that although the use of alloys can solve the drawbacks of a single metal as an electrocatalyst, it still has structural defects. In view of this, the present invention continues to study, cut the formed alloy ingot into pieces, and then carry out acid-base corrosion, and use corrosion to construct a microscopic dual-mode nanopore morphology to improve the atomic utilization of active sites. If a specific pore structure and active site are to be formed, it is necessary to strictly limit the ratio between palladium-metal and palladium-silver in the present invention, specifically limit the atomic ratio of palladium to metal near the palladium-metal eutectic point, and limit the atomic ratio of palladium to silver to the palladium-silver mutual solubility region. Moreover, when the atomic ratio is selected in the palladium-silver mutual solubility region, in order to ensure a stable palladium main skeleton, the palladium content cannot be too small, and the palladium atomic ratio needs to be between 50% and 100%. Analysis of the reason: The atomic ratio of palladium to metal is selected close to the eutectic point, which can make the alloy form a uniform microstructure during the solidification process. This is because the eutectic alloy will form a stable and uniformly distributed two-phase structure during solidification. When the easily corroded metal is subsequently removed by acid-base corrosion, the palladium-silver skeleton left behind will form a three-dimensional interconnected dual-mode pore structure, which is conducive to improving the specific surface area of ​​the catalyst and the material diffusion efficiency. The atomic ratio of palladium to silver is selected within the mutual solubility region of the palladium-silver alloy phase diagram, which means that palladium and silver can form a single-phase structure in the alloy, which helps to ensure the formation of uniform and continuous nanoscale metal ligaments during the corrosion process. At the same time, the uniform distribution of palladium and silver can also improve the mechanical strength and stability of the entire material.

[0012] Preferably, in step (1), the metal particles susceptible to acid and alkali corrosion are one of aluminum, zinc, chromium and magnesium.

[0013] Preferably, in step (1), the metal particles susceptible to acid-base corrosion are aluminum, and the atomic ratio of palladium, silver and aluminum is (15-18): (2-5): (78-82).

[0014] The present invention can adjust the pore size and component distribution of the final nanoporous material by controlling the ratio of palladium, silver and aluminum, thereby optimizing its performance as an electrocatalyst. Appropriate porosity can not only increase the number of active sites, but also promote the rapid transfer of reactants and products and reduce diffusion limitations.

[0015] Preferably, in step (2), the thickness of the alloy sheet is 100-1000 μm.

[0016] Preferably, in step (3), the acid solution is one or more of a hydrochloric acid aqueous solution, a nitric acid aqueous solution and a sulfuric acid aqueous solution, the concentration of the acid solution is 0.5-3 mol / L, and the soaking time is 6-10 h.

[0017] Preferably, in step (3), the alkaline solution is one or both of a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution, the concentration of the alkaline solution is 5-8 mol / L, and the soaking time is 1-3 h.

[0018] The second aspect of the present invention provides a nanoporous palladium-silver alloy self-supporting electrode, which is prepared by the above-mentioned preparation method.

[0019] Preferably, the nanoporous palladium-silver alloy self-supporting electrode comprises three-dimensionally interconnected dual-mode open pores and interconnected nanoscale metal ligaments.

[0020] The third aspect of the present invention provides an application of a nanoporous palladium-silver alloy self-supporting electrode, specifically an application of the nanoporous palladium-silver alloy self-supporting electrode in the electrocatalytic hydrogenation of phenol to prepare cyclohexanone.

[0021] Therefore, the present invention adopts the above-mentioned nanoporous palladium-silver alloy self-supporting electrode and its preparation method and application, which has the following beneficial effects: (1) The composition of the nanoporous alloy of the present invention can be continuously adjusted within a wide range, which is conducive to the flexible design and construction of active sites. In addition, the self-supporting ligament structure of the nanoporous alloy significantly improves the stability of the electrocatalytic material and structurally avoids the occurrence of problems such as agglomeration and shedding of active materials.

[0022] (2) The nanoporous palladium-silver alloy self-supporting electrode prepared by the present invention has three-dimensional interconnected dual-mode open channels and interconnected nanoscale metal ligaments. The nanoporous alloy exhibits many characteristics such as high specific surface area, high conductivity and rapid mass transfer, which is beneficial to provide sufficient active sites in the electrocatalytic process and accelerate the catalytic reaction kinetics.

[0023] (3) The present invention utilizes the coordination effect produced by alloying to optimize the electronic structure of active metal elements, providing the possibility for regulating the adsorption energy and reducing the intermediate reaction energy barrier, thereby improving the activity and selectivity of the electrode for partial hydrogenation of phenol.

[0024] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the preparation route of the nanoporous palladium-silver alloy self-supporting electrode of Example 1; Figure 2 This is the XRD pattern of the nanoporous palladium-silver alloy self-supporting electrode prepared in Example 1; Figure 3The morphology and phase structure characterization diagrams of the nanoporous palladium-silver alloy self-supporting electrode prepared in Example 1, including: (a) SEM image of the nanoporous palladium-silver alloy self-supporting electrode; (b) TEM image of the nanoporous palladium-silver alloy self-supporting electrode (low magnification); (c) HRTEM image of the nanoporous palladium-silver alloy self-supporting electrode; (d) element distribution diagram of the nanoporous palladium-silver alloy self-supporting electrode; Figure 4 The chemical composition and electronic structure characterization diagram of the nanoporous palladium-silver-aluminum alloy self-supporting electrode prepared in Example 1, including: (a) the full XPS spectrum of the nanoporous palladium-silver alloy self-supporting electrode; (b) the high-resolution Pd 3d XPS spectrum of the nanoporous palladium-silver alloy self-supporting electrode; (c) the high-resolution Ag 3d XPS spectrum of the nanoporous palladium-silver alloy self-supporting electrode; (d) the UV spectrum of the nanoporous palladium-silver alloy self-supporting electrode; Figure 5 The nanoporous Pd-Ag alloy self-supporting electrode is at 0~-0.6 V and at 10 mV s -1 Linear scan polarization curve measured at a scan rate of ; Figure 6 A comparison chart of the electrocatalytic phenol hydrogenation conversion rate and product selectivity of the nanoporous palladium-silver alloy self-supporting electrode prepared in Example 1-2 and Comparative Example 1-2 with that of nanoporous pure palladium; Figure 7 This is a comparison of the Faradaic efficiency and current density of the nanoporous palladium-silver alloy self-supporting electrode for electrocatalytic phenol hydrogenation with that of nanoporous pure palladium; Figure 8 The selectivity and conversion rate of phenol hydrogenation at different potentials on nanoporous palladium-silver alloy self-supporting electrode; Fig. 9 The Faradaic efficiency and conversion rate of the nanoporous palladium-silver alloy self-supporting electrode for the hydrogenation of phenol at different concentrations of 10 mM, 20 mM, and 30 mM; Fig.10 The Faradaic efficiency and conversion rate results of the nanoporous Pd-Ag-Al alloy self-supporting electrode in 10 hydrogenation cycles at a potential of -0.05 V (vs. RHE). DETAILED DESCRIPTION

[0026] The present invention will be further described below. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and a specific operation process, but the present invention is not limited to this embodiment.

[0027] Example 1 like Figure 1 As shown, a method for preparing a nanoporous palladium-silver alloy self-supporting electrode comprises the following steps: (1) Palladium (Pd), silver (Ag) and aluminum (Al) are mixed, with the atomic ratio of Pd, Ag and Al being 16:4:80 and the total weight being 4 g. The mixture is then placed in a melting furnace and melted under an inert atmosphere. During the melting process, a current of 120 A is applied to the tungsten electrode, and the melting temperature can reach about 3000 °C, so that the metal raw materials are completely melted. The current is turned off, and the molten liquid metal is rapidly cooled and solidified in a crucible with cooling water to form an alloy ingot. The melting is repeated 4 times to ensure that the composition of the alloy ingot is uniform. (2) Cutting the alloy ingot into alloy sheets with a thickness of 400 μm; (3) The alloy sheet was immersed in a potassium hydroxide aqueous solution for corrosion. The concentration of the potassium hydroxide aqueous solution was 6 mol / L. The immersion time was 1.5 h and the corrosion temperature was 80 °C. After corrosion, the alloy sheet was taken out, then washed with ultrapure water and vacuum dried to obtain a nanoporous palladium-silver alloy self-supporting electrode.

[0028] Example 2 Repeat the first two steps in Example 1 to obtain an alloy sheet. The alloy sheet was immersed in a nitric acid aqueous solution for corrosion, the concentration of the nitric acid aqueous solution was 0.5 mol / L, the immersion time was 8 h, and the corrosion temperature was 80 ° C. After corrosion, the alloy sheet was taken out, then washed with ultrapure water, and vacuum dried to obtain a nanoporous palladium silver alloy self-supporting electrode.

[0029] Comparative Example 1 The difference from Example 1 is that nanoporous pure palladium is used as the self-supporting electrode. The following steps are included: (1) Pd and Al are mixed, with an atomic ratio of 20:80 and a total weight of 4 g. The mixture is then placed in a melting furnace and melted under an inert atmosphere. During the melting process, a current of 120 A is applied to the tungsten electrode, and the melting temperature can reach about 3000 °C, so that the metal raw materials are completely melted. The current is turned off, and the molten liquid metal quickly solidifies in a crucible with cooling water to form a PdAl alloy ingot. The melting is repeated 4 times to ensure that the composition of the alloy ingot is uniform; (2) Cutting the alloy ingot into alloy sheets with a thickness of 400 μm; (3) The alloy sheet was immersed in a potassium hydroxide aqueous solution for corrosion. The concentration of the potassium hydroxide aqueous solution was 6 mol / L and the immersion time was 1.5 h. After corrosion, the alloy sheet was taken out, then washed with ultrapure water and vacuum dried to obtain a nanoporous pure palladium self-supporting electrode.

[0030] Comparative Example 2 The difference from Example 1 is that the atomic ratios of palladium, silver and aluminum are different. Pd, Ag and Al are mixed, the atomic ratio of Pd, Ag and Al is 14:6:80, and the total weight is 4 g. Then, they are placed in a smelting furnace for smelting under an inert atmosphere. During smelting, the current applied to the tungsten electrode is 120 A, and the smelting temperature can reach about 3000 °C, so that the metal raw material is completely melted. Turn off the current, and the molten liquid metal quickly solidifies in a crucible with cooling water to form a PdAl alloy ingot. Repeat the smelting 4 times to ensure that the composition of the alloy ingot is uniform; (2) Cutting the alloy ingot into alloy sheets with a thickness of 400 μm; (3) The alloy sheet was immersed in a potassium hydroxide aqueous solution for corrosion. The concentration of the potassium hydroxide aqueous solution was 6 mol / L. The immersion time was 1.5 h and the corrosion temperature was 80 °C. After corrosion, the alloy sheet was taken out, then washed with ultrapure water and vacuum dried to obtain nanoporous palladium-silver alloy self-supporting electrodes with different proportions.

[0031] Test Example 1 The nanoporous palladium-silver alloy self-supporting electrode prepared in Example 1 was characterized. The characterization results are shown in Figures 2~4 .

[0032] like Figure 2 As shown in the figure, the positions of the diffraction peaks correspond to the pure metal Pd phase (JCPDS 65-2867), which is consistent with the structure of the nanoporous PdAl alloy electrode. The Ag (JCPDS 65-2871) phase does not exist in the PdAgAl alloy, indicating that Pd atoms and Ag atoms are completely soluble in each other, and Ag atoms are solid dissolved in the Pd phase.

[0033] like Figure 3 As shown in the figure, the nanoporous palladium-silver alloy self-supporting electrode has a dual-mode nanoporous structure, including three-dimensional interconnected open channels and interconnected nanoscale metal ligaments, among which the open micrometer-sized large-size channels provide a fast channel for the mass transfer behavior of the reaction process. Combined with low-magnification TEM analysis, it can be seen that the uniformly distributed nanoscale pores on the metal sheet have an average size of about 10 nm. Such uniform and abundant pores significantly increase the specific surface area and provide abundant and accessible active sites for the catalytic reaction process. Through HRTEM images, crystal planes with a spacing of 0.228 nm can be observed, which corresponds to the (111) crystal plane of Pd. The element distribution map confirms that the Pd element and the Ag element are uniformly distributed on the metal ligaments, confirming the full solid solution of Ag in the Pd phase.

[0034] like Figure 4 As shown in the figure, the chemical state and electronic structure characteristics of the nanoporous PdAg alloy self-supporting electrode were characterized, including XPS and ultraviolet spectroscopy (UPS) technology, proving the electronic interaction between Pd and Ag. Figure 4 As shown in (a), the presence of Pd and Ag elements was observed in the XPS spectrum of the PdAg alloy. Figure 4 As shown in (b), the high-resolution Pd3d XPS spectrum of the PdAg alloy has a pair of main peaks at 335.85 and 341.13 eV, corresponding to the metallic Pd 3d 5 / 2 and Pd 3d 3 / 2 . It has a certain degree of positive shift relative to Pd metal, indicating that there is electronic interaction between Pd and Ag. Figure 4 As shown in (c), the high-resolution Ag 3d XPS spectrum of the PdAg alloy has a pair of main peaks at 368.34 and 374.34 eV, corresponding to the metallic Ag3d 5 / 2 and Ag 3d 3 / 2 .like Figure 4 As shown in (d), the UPS spectrum of the PdAg alloy shows that under the action of Ag, the d-band center of the alloy has shifted significantly.

[0035] Example 3 Assembly of the electrolytic cell: The prepared nanoporous palladium silver alloy self-supporting electrode (prepared in Example 1) was directly used as a working electrode, and assembled into a three-electrode system with an Ag / AgCl reference electrode and a 1 cm×1 cm Pt sheet counter electrode, and the electrolyte was a 0.5 M sulfuric acid aqueous solution. It was used in an H-type electrolytic cell in which a proton exchange membrane (Nafion membrane) separated the positive and negative electrodes, and the electrolytic cell was heated to 60°C in a water bath, stirred at 400 rpm, and argon was introduced for deoxygenation for 0.5 h.

[0036] The electrochemical test of the nanoporous Pd-Ag alloy self-supporting electrode was carried out. In the linear cyclic voltammetry curve test, the scanning voltage range was set to 0.05 V~-0.6 V (relative to RHE) and the scanning rate was 10 mV s -1 . After adding 10 mM phenol to the electrolyte, a constant potential test was carried out at a potential of -0.05 V (relative to RHE), and the amount of electricity passed in the test was 155 C. In the constant potential test at different potentials, the test potentials were -0.05 V, -0.15 V, -0.25 V, and -0.35 V (relative to RHE), and the amount of electricity passed in the test was 155 C. In the constant potential test of different phenol concentrations, 10 mM, 20 mM, and 30 mM phenol were added to the electrolyte, respectively, and the amounts of electricity passed in the test were 155 C, 310 C, and 465 C, respectively. In the constant potential hydrogenation cycle test, the potential was set to -0.05 V (relative to RHE) and cycled 10 times. For all the above product analyses, the electrolyte after the test was extracted with dichloromethane, and the products were detected by gas chromatography.

[0037] Test Example 2 The electrochemical performance and product analysis test results in Example 2 are as follows Figure 5-Figure 10 shown.

[0038] Nanoporous Pd-Ag alloy self-supporting electrode in 0.5 M sulfuric acid solution at 10 mV s -1 Comparison of LSV polarization curves with and without 10 mM phenol at the scanning rate Figure 5 In the presence of 10 mM phenol in the electrolyte, the nanoporous Pd-Ag alloy self-supporting electrode showed a significantly increased reduction current, which preliminarily indicated that the Pd-Ag alloy had a certain hydrogenation activity for phenol.

[0039] The product distribution of the nanoporous palladium-silver alloy self-supporting electrode of Example 1-2 and Comparative Example 1-2 at -0.05 V constant potential test was analyzed by gas chromatography. The results are as follows: Figure 6 As shown in Table 1. The electrode prepared in Example 1 can achieve a conversion rate of 91.2% for phenol and has an ultra-high selectivity for the high value-added product cyclohexanone, up to ~98.9%.

[0040]

[0041] like Figure 7 As shown in Figure 1, the Faradaic efficiency of the electrode prepared in Example 1 for producing cyclohexanone reached ~90%, and the current density at -0.05 V reached 79 mA cm -2 .

[0042] like Figure 8 As shown, the electrode prepared in Example 1 can maintain ultra-high cyclohexanone selectivity in a wide voltage range, all above 98.5%.

[0043] like Fig. 9 As shown, in a series of high concentration phenol electrolyte environments of 10 mM, 20 mM, and 30 mM, the nanoporous palladium-silver alloy self-supporting electrode prepared in Example 1 exhibited high Faradaic efficiency and phenol conversion rate for producing cyclohexanone.

[0044] like Fig.10 As shown, in a 0.5 M H2SO4 electrolyte containing 10 mM phenol, at a potential of -0.05 V, after 10 rounds of hydrogenation cycles, the nanoporous palladium-silver alloy self-supporting electrode prepared in Example 1 can maintain stable phenol hydrogenation activity and selectivity, indicating the high stability of this self-supporting electrode.

[0045] Therefore, the present invention adopts the above-mentioned nanoporous palladium-silver alloy self-supporting electrode and its preparation method and application, and utilizes a simple and feasible melting-etching technology to construct a palladium-silver alloy with a three-dimensional dual-continuous nanoporous structure as a self-supporting electrode for the electrocatalytic phenol hydrogenation reaction. By virtue of the high conductivity, large specific surface area, and rapid mass transfer capability of the unique dual-mode nanoporous structure, as well as the ligand effect produced by alloying, the nanoporous palladium-silver alloy exhibits excellent phenol partial hydrogenation activity, selectivity (phenol conversion rate ~91.2%, cyclohexanone selectivity ~98.9%) and cycle stability.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a nanoporous palladium-silver alloy self-supporting electrode, characterized in that: The following steps are involved: (1) palladium, silver and metal particles susceptible to acid and alkali corrosion are mixed, then placed in a smelting furnace for smelting under an inert atmosphere, and then cast and cooled to obtain an alloy ingot; (2) Cutting the alloy ingot into alloy sheets; (3) The alloy sheet is immersed in an acid solution or an alkaline solution for corrosion, and the alloy sheet is taken out after corrosion, and then cleaned and dried to obtain a nanoporous palladium-silver alloy self-supporting electrode.

2. The method for preparing a nanoporous palladium-silver alloy self-supporting electrode according to claim 1, characterized in that: In step (1), the atomic ratio between palladium and metal particles susceptible to acid-base corrosion is selected according to the palladium-metal alloy phase diagram, and the atomic ratio of palladium to metal near the palladium-metal eutectic point is selected; the atomic ratio between palladium and silver is selected according to the palladium-silver alloy phase diagram, and the atomic ratio of palladium to silver in the palladium-silver mutual solubility region is selected.

3. The method for preparing a nanoporous palladium-silver alloy self-supporting electrode according to claim 2, characterized in that: In step (1), the metal particles susceptible to acid and alkali corrosion are one of aluminum, zinc, chromium and magnesium.

4. The method for preparing a nanoporous palladium-silver alloy self-supporting electrode according to claim 3, characterized in that: In step (1), the metal particles susceptible to acid-base corrosion are aluminum, and the atomic ratio of palladium, silver and aluminum is (15-18): (2-5): (78-82).

5. The method for preparing a nanoporous palladium-silver alloy self-supporting electrode according to claim 1, characterized in that: In step (2), the thickness of the alloy sheet is 100-1000 μm.

6. The method for preparing a nanoporous palladium-silver alloy self-supporting electrode according to claim 1, characterized in that: In step (3), the acid solution is one or more of a hydrochloric acid aqueous solution, a nitric acid aqueous solution and a sulfuric acid aqueous solution, the concentration of the acid solution is 0.5-3 mol / L, and the soaking time is 6-10 h.

7. The method for preparing a nanoporous palladium-silver alloy self-supporting electrode according to claim 1, characterized in that: In step (3), the alkaline solution is one or both of a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution, the concentration of the alkaline solution is 5-8 mol / L, and the soaking time is 1-3 h.

8. A nanoporous palladium-silver alloy self-supporting electrode, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

9. The nanoporous palladium-silver alloy self-supporting electrode according to claim 8, characterized in that: The nanoporous palladium-silver alloy self-supporting electrode consists of three-dimensional interconnected dual-mode open channels and interconnected nanoscale metal ligaments.

10. Use of a nanoporous palladium-silver alloy self-supporting electrode according to any one of claims 8 to 9, characterized in that: Application of nanoporous palladium-silver alloy self-supporting electrode in electrocatalytic phenol hydrogenation to cyclohexanone.

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