An ultra-thin palladium-tin nanonet catalyst, its preparation method and application

Abstract

The present invention discloses an ultrathin palladium-tin nanonet catalyst, a preparation method thereof, and an application thereof. In the present invention, palladium metal salt and tin metal salt are used as precursors, iron metal salt or zinc metal salt is used as a sacrificial pore-forming substance, N,N-dimethylformamide is used as a solvent, acetic acid is used as an etchant, and it is heated together with tungsten hexacarbonyl. The thermal decomposition of tungsten hexacarbonyl will generate carbon monoxide, and carbon monoxide can limit the longitudinal growth of palladium. Therefore, the present invention uses a simple one-step method to quickly realize the synthesis of an ultrathin two-dimensional palladium-tin nanonet catalyst with atomic-level thickness, and no additional surfactant needs to be added. The prepared catalyst has a higher proportion of edge low-coordination atoms and a higher electrochemically active area. The present invention also applies this material to the ethanol oxidation reaction, achieving high activity and high C1 selectivity for electrocatalytic ethanol oxidation.

Description

Technical Field

[0001] The present invention belongs to the field of chemical catalysts, and particularly relates to an ultrathin palladium-tin nanonet catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous intensification of the energy crisis and the increasing severity of environmental pollution, the global energy utilization pattern is undergoing a major transformation. Exploring new ways of clean, efficient and sustainable energy utilization has become a research hotspot in the world today. Hydrogen-oxygen fuel cells fueled by hydrogen have become the fastest-growing fuel cells so far. However, at present, there are still major bottlenecks and safety hazards in the production, storage and transportation of hydrogen, which limit the development and practical application of hydrogen-oxygen fuel cells. Direct alcohol fuel cells are a new type of fuel cell using liquid alcohols as fuels. Due to their low storage risk, easy replenishment and high energy density characteristics, they are considered to be a very promising energy device. In terms of the selection of anode fuels for direct alcohol fuel cells, compared with methanol with the simplest structure, ethanol as a fuel has lower toxicity, lower membrane permeability, higher energy density and biological renewability.

[0003] However, the practical application of direct ethanol fuel cells is severely hindered by the slow kinetics and incomplete reaction of the anodic ethanol oxidation reaction. It is generally believed that the ethanol oxidation reaction follows two parallel and competing paths. The complete ethanol oxidation path (C1 path) from ethanol to CO 2 involves 12 electron transfers and C-C bond cleavage, while the C2 path from ethanol to acetaldehyde / acetic acid involves 2 / 4 electron transfers without breaking the C-C bond. Obviously, improving the selectivity of the C1 path is of great significance for improving the energy conversion efficiency of direct ethanol fuel cells. However, so far, platinum (Pt) and palladium (Pd) are considered to be the most advanced single-metal catalysts for ethanol oxidation reactions. However, the selectivity of the C1 path on pure Pt and Pd catalysts is still very low (<7.5%).

[0004] With the rapid development of anion exchange membranes and cathode oxygen reduction reaction electrocatalysts, alkaline direct ethanol fuel cells are receiving increasing attention. Due to the more favorable kinetics of the anodic ethanol oxidation reaction and cathodic oxygen reduction reaction in alkaline electrolytes compared to acidic ones, the performance of alkaline direct ethanol fuel cells has been significantly improved. In alkaline electrolytes, the ethanol oxidation activity of Pd is significantly higher than that of Pt and reaches the highest among all known single-metal catalysts. Therefore, the development of Pd-based ethanol oxidation electrocatalysts is considered to contribute to the development and application of alkaline direct ethanol fuel cells. A common catalyst optimization strategy is to alloy Pd with other oxygenophilic metals such as tin, iron, nickel, and zinc. The enhanced catalytic performance is mainly attributed to the bifunctional mechanism. The easy adsorption of O and OH on the oxygenophilic sites of the catalyst can promote the removal of toxic intermediates, thereby enhancing the activity and stability of the ethanol oxidation reaction. However, it is still difficult to solve the problem of low C1 path selectivity through this alloying strategy.

[0005] Recently, low-coordination site engineering has been considered a promising catalyst design strategy for effectively improving the performance of electrocatalysts. Ultrathin two-dimensional nanosheets with atomic thickness are a new type of catalyst material for achieving a high density of low-coordination atoms. Due to excellent properties such as high atomic utilization efficiency, outstanding electron mobility, and abundant low-coordination edge sites, ultrathin two-dimensional noble metal nanosheets show broad prospects in electrocatalytic applications. However, the low-coordination atoms in ultrathin two-dimensional nanosheet materials are mainly located at the edge positions of the nanosheets, while a large number of atoms on the inner surface maintain relatively high coordination numbers, resulting in a relatively low proportion of low-coordination sites and still low C1 path selectivity and catalytic activity of the catalyst. Summary of the Invention

[0006] To solve the above problems, the present invention provides an ultrathin palladium-tin nanonet catalyst, its preparation method, and application. The present invention uses a simple one-step method to quickly synthesize an ultrathin two-dimensional palladium-tin nanonet catalyst with atomic thickness. The network structure enables it to have a significantly higher proportion of edge low-coordination atoms compared to the nanosheet structure, and this material is applied to the ethanol oxidation reaction, achieving high activity and high C1 selectivity for electrocatalytic ethanol oxidation.

[0007] To achieve the above invention purposes, the present invention is implemented by the following technical solutions:

[0008] The present invention provides a preparation method of an ultrathin palladium-tin nanonet catalyst, which includes the following steps:

[0009] (1) Mix N,N-dimethylformamide and an etchant evenly;

[0010] (2) Dissolve the precursor, sacrificial pore-forming substance, and tungsten hexacarbonyl in the mixed solution of step (1), heat it at a high temperature, then cool it to room temperature, and collect the ultrathin palladium-tin nanonet catalyst through centrifugation and washing.

[0011] The precursor is a palladium metal salt and a tin metal salt; the sacrificial pore-forming substance is at least one of an iron metal salt and a zinc metal salt.

[0012] Further, the palladium metal salt is sodium palladium chloride, and the tin metal salt is tin chloride.

[0013] Further, the iron metal salt is iron chloride, and the zinc metal salt is zinc chloride.

[0014] Further, the mass ratio of sodium palladium chloride to tin chloride is 1 - 1.5:1.

[0015] Further, the mass ratio of the precursor to the sacrificial pore-forming substance is 2 - 3:1.

[0016] Further, the mass ratio of the precursor to tungsten hexacarbonyl is 1:1.5 - 2.

[0017] Further, the etching agent is acetic acid; the volume ratio of N,N-dimethylformamide to the etching agent is 4 - 5:1.

[0018] Further, the target temperature of the high-temperature heating is 140°C - 180°C, and it is heated to the target temperature within 15 minutes, and the heating time is 1 - 1.5 hours.

[0019] Preferably, the target temperature of the high-temperature heating is 160°C.

[0020] The present invention also provides an ultrathin palladium-tin nanonet catalyst, which is prepared by the described preparation method, and its electrochemically active area is 55 - 60 m 2 / g Pd , and it has an ultrathin structure with a thickness less than 1 nm.

[0021] Further, the network structure of the ultrathin palladium-tin nanonet catalyst endows it with a large number of edge low-coordination atomic sites.

[0022] The present invention also provides the application of the described ultrathin palladium-tin nanonet catalyst in direct ethanol fuel cells or electrocatalytic ethanol oxidation.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] The present invention utilizes a simple one-step method to rapidly realize the synthesis of an ultra-thin two-dimensional palladium-tin nanomesh catalyst with atomic-level thickness, and does not require the addition of an additional surfactant. The mesh structure is manufactured by etching a sacrificial metal and the sheet-like macrostructure is maintained; the ultra-thin characteristics and mesh structure enable it to have a significantly higher proportion of edge low-coordinated atoms and a higher electrochemically active area compared to the nanosheet structure. The present invention also applies the material to the ethanol oxidation reaction, achieving high activity and high C1 selectivity for electrocatalytic ethanol oxidation. In addition, the present invention does not involve secondary heating or the addition of a surfactant, thereby making the ultra-thin two-dimensional palladium-tin nanomesh catalyst easy to clean and simple to synthesize, and the mass activity of the synthesized catalyst is 10.8 A / mg Pd The specific surface area activity is 22.1 mA / cm 2 , the electrochemical active area is 57.0m 2 / g Pd , which are significantly higher than the existing technology, so it has a good market prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is an electron microscope image of the PdSn nanonet of Example 1; wherein a is a scanning electron microscope (SEM) image of the PdSn nanonet, b is a transmission electron microscope (TEM) image of the PdSn nanonet, and c is Figure 1 An enlarged view of a portion of the area in b.

[0026] Figure 2 The atomic force microscope (AFM) image and thickness distribution diagram of the PdSn nanomesh in Example 1 are shown.

[0027] Figure 3 This is the TEM image of the PdSn nanomesh corresponding to Example 2.

[0028] Figure 4 This is the TEM image of the PdSn nanomesh corresponding to Example 3.

[0029] Figure 5 This is the TEM image of the PdSn nanomesh corresponding to Example 4.

[0030] Figure 6 These are the SEM and TEM images of the Pd nanosheets corresponding to Comparative Example 1; wherein a is the SEM image of the Pd nanosheets, and b and c are the TEM images of the Pd nanosheets.

[0031] Figure 7 These are the SEM and TEM images of the PdSn nanosheets corresponding to Comparative Example 2; wherein a is the SEM image of the PdSn nanosheets, and b and c are the TEM images of the PdSn nanosheets.

[0032] Figure 8X-ray diffraction (XRD) patterns of Pd nanosheets supported on carbon powder (Pd nanosheets / C) corresponding to Comparative Example 1, PdSn nanosheets supported on carbon powder (PdSn nanosheets / C) corresponding to Comparative Example 2, and PdSn nanomesh supported on carbon powder (PdSn nanomesh / C) corresponding to Example 2.

[0033] Figure 9 Comparisons of specific surface area activity and mass activity of commercial Pd / C, Pd nanosheets / C, PdSn nanosheets / C, and PdSn nanomesh / C for electrocatalytic ethanol oxidation; where a is the specific surface area activity curve, b is the mass activity curve, and c is the summary comparison chart of the highest specific surface area activity and the highest mass activity.

[0034] Figure 10 Comparisons of the Faraday efficiency of the C1 pathway for electrocatalytic ethanol oxidation of commercial Pd / C, Pd nanosheets / C, PdSn nanosheets / C, and PdSn nanomesh / C. Detailed Description of the Invention

[0035] The technical solutions of the present invention will be further described in detail in conjunction with the following specific examples.

[0036] In the following examples, unless otherwise specified, the experimental methods used are all conventional methods, and the materials, reagents, etc. used can be purchased from biological or chemical reagent companies.

[0037] Example 1

[0038] Dissolve 11.3 mg of sodium palladium chloride hydrate, 8.5 mg of tin chloride hydrate, 6.8 mg of iron chloride hydrate, and 31 mg of tungsten hexacarbonyl in a round-bottom flask containing a mixed solution of 8 mL of N,N-dimethylformamide and 2 mL of acetic acid. Seal the flask, then heat it to 160 °C within 15 minutes and keep it for 1 hour under magnetic stirring. After the mixture is naturally cooled to room temperature, collect the product PdSn nanomesh by centrifuging at 6000 rpm for 5 minutes and washing three times with ethanol.

[0039] Example 2

[0040] Dissolve 11.3 mg of sodium palladium chloride hydrate, 8.5 mg of tin chloride hydrate, 8.0 mg of zinc chloride hydrate, and 31 mg of tungsten hexacarbonyl in a round-bottom flask containing a mixed solution of 8 mL of N,N-dimethylformamide and 2 mL of acetic acid. Seal the flask, then heat it to 160 °C within 15 minutes and keep it for 1 hour under magnetic stirring. After the mixture is naturally cooled to room temperature, collect the product PdSn nanomesh by centrifuging at 6000 rpm for 5 minutes and washing three times with ethanol.

[0041] Example 3

[0042] 11.3 mg of sodium palladium chloride hydrate, 8.5 mg of tin chloride hydrate, 6.8 mg of iron chloride hydrate and 31 mg of tungsten hexacarbonyl were dissolved in a round-bottom flask containing a mixed solution of 8 mL of N,N-dimethylformamide and 2 mL of acetic acid. The flask was sealed and then heated to 140 °C within 15 minutes and maintained for 1 hour under magnetic stirring. After the mixture was naturally cooled to room temperature, the product PdSn nanomesh was collected by centrifuging at 6000 rpm for 5 minutes and washing three times with ethanol.

[0043] Example 4

[0044] 11.3 mg of sodium palladium chloride hydrate, 8.5 mg of tin chloride hydrate, 6.8 mg of iron chloride hydrate and 31 mg of tungsten hexacarbonyl were dissolved in a round-bottom flask containing a mixed solution of 8 mL of N,N-dimethylformamide and 2 mL of acetic acid. The flask was sealed and then heated to 180 °C within 15 minutes and maintained for 1 hour under magnetic stirring. After the mixture was naturally cooled to room temperature, the product PdSn nanomesh was collected by centrifuging at 6000 rpm for 5 minutes and washing three times with ethanol.

[0045] Comparative Example 1

[0046] 11.3 mg of sodium palladium chloride hydrate and 31 mg of tungsten hexacarbonyl were dissolved in a round-bottom flask containing a mixed solution of 8 mL of N,N-dimethylformamide and 2 mL of acetic acid. The flask was sealed and then heated to 160 °C within 15 minutes and maintained for 1 hour under magnetic stirring. After the mixture was naturally cooled to room temperature, the product Pd nanosheets were collected by centrifuging at 6000 rpm for 5 minutes and washing three times with ethanol.

[0047] Comparative Example 2

[0048] 11.3 mg of sodium palladium chloride hydrate, 8.5 mg of tin chloride hydrate and 31 mg of tungsten hexacarbonyl were dissolved in a round-bottom flask containing a mixed solution of 8 mL of N,N-dimethylformamide and 2 mL of acetic acid. The flask was sealed and then heated to 160 °C within 15 minutes and maintained for 1 hour under magnetic stirring. After the mixture was naturally cooled to room temperature, the product PdSn nanosheets were collected by centrifuging at 6000 rpm for 5 minutes and washing three times with ethanol.

[0049] Example 5

[0050] 1. Characterization methods

[0051] (1) Morphology analysis

[0052] The morphologies of the nanomaterials synthesized in the examples and comparative examples were characterized using a scanning electron microscope (SEM) and a transmission electron microscope (TEM), and the thickness of the nanomaterials was characterized using an atomic force microscope (AFM).

[0053] (2)Loading of the nanomaterials

[0054] For subsequent physical and chemical tests, the nanomaterials prepared in the examples and comparative examples were loaded on Ketjen black for further characterization. Briefly, the collected nanomaterials and 13 mg of Ketjen black were mixed in 10 mL of ethanol and sonicated for 30 minutes. The mixture was stirred overnight to ensure uniform deposition of the materials on the carbon. The product was collected by centrifugation at 8000 rpm for 5 minutes and dried overnight at 60 °C under vacuum to obtain the corresponding loaded nanomaterials, i.e., carbon-supported catalysts.

[0055] (3)Elemental composition and crystal structure analysis

[0056] The obtained carbon-supported catalysts were digested with aqua regia, and the proportion of the metal components of the catalysts was analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The crystal structure of the obtained carbon-supported catalyst materials was characterized using an X-ray diffractometer (XRD).

[0057] (4)Electrochemical tests

[0058] 4 mg of the carbon-supported catalyst material was added to 1 mL of ultrapure water, 1 mL of isopropanol, and 30 μL of Nafion solution. After sufficient ultrasonic dispersion, 5 μL was taken and drop-coated on a rotating disk glassy carbon electrode for electrochemical tests. The electrochemical active area of the catalyst was tested using a CO stripping experiment. First, CO was introduced into the electrolyte for at least 10 minutes to ensure complete adsorption of CO molecules on the catalyst; then, the electrode was immersed in fresh nitrogen-saturated electrode solution. The CO stripping cyclic voltammogram was recorded at a scanning rate of 20 mV / s in the potential range of 0 to 1.2 V (vs. RHE). The electrolyte solution for the electrocatalytic ethanol oxidation test was 1 M NaOH + 1 M ethanol, the counter electrode was a graphite rod, the reference electrode was Hg / HgO, and the scanning rate was 50 mV / s.

[0059] The products of the ethanol oxidation reaction were tested in an H-cell. The compartments of the working electrode and the reference electrode were separated from the other compartment of the counter electrode by an anion exchange membrane. 1 mg of the catalyst was coated on carbon paper as the working electrode, and a Hg / HgO electrode and a graphite rod were used as the reference electrode and the counter electrode. In 1 M NaOH and 1 M ethanol, the working electrode was maintained at a constant potential of 0.6 V, 0.7 V, and 0.8 V (relative to the reversible hydrogen electrode). After electrolysis for 3 hours, the solution from the anodic compartment was collected for further product analysis.

[0060] 2. Characterization conclusion

[0061] SEM and TEM images ( Figure 1 ) shows that the nanomaterial synthesized in Example 1 presents a flower-like assembly structure self-assembled from ultrathin nanosheets. The enlarged TEM image ( Figure 1 c) shows that there are abundant holes in the nanosheets, and the nanosheets maintain an interconnected network structure. The structural characteristics of the nanonet make the material have a large number of edge low-coordinated atoms. AFM image ( Figure 2 ) shows that the thickness of the material is less than 1 nm, indicating that it forms an ultra-thin two-dimensional structure with atomic thickness. The final Pd / Sn / Fe atomic ratio in the product obtained in Example 1 is 73.8: 25.6: 0.6 as measured by inductively coupled plasma mass spectrometry (ICP-MS), which indicates that the content of Fe element in this material is negligible. Combined with the characterization of the subsequent comparative examples, it can be seen that active metal elements such as Fe element that are easily etched by acetic acid are the key to forming a nano-mesh structure.

[0062] Example 2 is to replace the iron precursor in Example 1 with a zinc precursor. TEM images ( Figure 3 ) characterization shows that an ultra-thin nano-mesh structure similar to that of Example 1 is also formed. ICP-MS also confirms that the content of zinc in the product is negligible, and zinc can also be etched as an active metal.

[0063] Examples 3 and 4 are obtained by changing the heating temperature of Example 1 to 140°C and 180°C, respectively. Figure 4 and Figure 5 ) characterization shows that nano-mesh structures can be synthesized at 140-180 degrees, but some mesh structures at 140°C are not connected to other mesh structures, which may be due to the slow reaction rate caused by the low temperature; the nano-mesh structure formed at 180°C has weak connectivity, and many linear structures are cut out from the sheet structure, which may be due to the enhanced etching effect caused by high temperature.

[0064] In order to verify the role of metal precursors such as iron and zinc, only palladium precursor was added to comparative example 1, and palladium precursor and tin precursor were added to comparative example 2. In comparative example 1, complete Pd nanoflowers were synthesized without adding tin and iron precursors, showing the neat morphology of self-assembled flower-like nanosheets ( Figure 6 ). This nanomaterial is complete in shape and has no visible holes from the magnified TEM image. Comparative Example 2 synthesized PdSn nanosheets, which are different in structure from Pd nanosheets in that the nanosheet assemblies are obviously curled and irregular ( Figure 7), which may be due to the tensile strain effect caused by the insertion of larger-radius tin atoms into the palladium face-centered cubic. The overall nanosheet remains intact without the appearance of a reticular structure. The structure of PdSn nanosheets synthesized without iron and zinc precursors demonstrates the crucial role of acetic acid etching of iron and zinc in the formation of a highly porous reticular structure.

[0065] X-ray diffraction (XRD) was used to further investigate the crystal structure of the prepared carbon-supported catalysts ( Figure 8 ). The XRD patterns of Pd nanosheet / C, PdSn nanosheet / C, and PdSn nanonet / C all showed typical face-centered cubic structures, indicating that the structures of PdSn nanosheet / C and PdSn nanonet / C are substitutional solid solution alloy phases. Compared with Pd nanosheet / C, the diffraction peaks of PdSn nanosheet / C and PdSn nanonet / C shifted negatively because Pd was replaced by Sn atoms with larger atomic radii.

[0066] The electrochemical active surface areas of the commercial Pd / C catalyst (purchased from Johnson Matthey Catalyst Company) and the synthesized carbon-supported catalysts were tested using the CO stripping experiment. The results (Table 1) show that compared with Pd nanosheet / C (39.4 m 2 / g Pd ), PdSn nanosheet / C (41.7 m 2 / g Pd ), the electrochemical active surface area of PdSn nanonet / C was significantly increased to 57.0 m 2 / g Pd , even better than that of the commercial Pd / C catalyst. This can be attributed to the fact that the reticular structure increases the exposed sites of the catalyst, and the larger electrochemical active surface area helps to make full use of the precious metal and is beneficial to the improvement of mass activity.

[0067] Table 1 Electrochemical active surface areas of the catalysts

[0068] Catalyst <![CDATA[Electrochemical active area (m 2 / g Pd )]]> Commercial Pd / C 50.8 Pd nanosheets (Comparative Example 1) / C 39.4 PdSn nanosheets (Comparative Example 2) / C 41.7 PdSn nanomesh (Example 1) / C 57.0

[0069] In an electrolyte of 1 M NaOH + 1 M ethanol, the electrocatalytic ethanol oxidation specific surface area activity and mass activity of the commercial Pd / C catalyst and the carbon-supported catalysts were evaluated at a scanning rate of 50 mV / s. Figure 9 a shows the specific surface area activities of the four carbon-supported catalysts. The calculated specific surface area activity of PdSn nanonet / C was 22.1 mA / cm 2 , higher than that of the commercial Pd / C (3.1 mA / cm 2 ), Pd nanosheet / C (5.2 mA / cm 2 ) and PdSn nanosheet / C (8.8 mA / cm 2) have specific surface activities that are approximately 7.1 times, 4.3 times, and 2.5 times higher, respectively. The mass activity of PdSn nanomesh / C remains extremely prominent. As shown in Figure 9 b of Pd , the mass activity of PdSn nanomesh / C (10.8 A / mg Pd ) is also much higher than that of commercial Pd / C (1.1 A / mg Pd ), Pd nanosheet / C (2.1 A / mg Pd ).

[0070] By analyzing the composition of the solution at different potentials, the products of electrocatalytic ethanol oxidation by different carbon-supported catalysts can be quantified ( Figure 10 ). It is worth noting that at 0.6 V, 0.7 V, and 0.8 V, the Faraday efficiencies of C1 products on PdSn nanomesh / C are 31.0%, 27.1%, and 21.3%, which are much higher than those of the other three catalysts. The significantly increased Faraday efficiency of C1 products emphasizes the special role of PdSn nanomesh / C in promoting the C-C bond cleavage during the oxidation process of ethanol molecules, which greatly contributes to the improvement of ethanol oxidation activity.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions required to be protected by the present invention.

Claims

1. A method for preparing an ultrathin palladium-tin nanonet catalyst, characterized in that: The following steps are involved: (1) Mix N,N-dimethylformamide and etchant evenly; (2) dissolving the precursor, sacrificial pore-forming material, and tungsten hexacarbonyl in the mixed solution of step (1), heating the solution at high temperature, cooling the solution to room temperature, and washing the solution by centrifugation to obtain an ultrathin palladium-tin nanonet catalyst; The precursor is a palladium metal salt and a tin metal salt; the sacrificial pore-forming substance is at least one of an iron metal salt and a zinc metal salt; The palladium metal salt is sodium chloropalladate, and the tin metal salt is tin chloride; the mass ratio of the sodium chloropalladate to the tin chloride is 1-1.5:1; The mass ratio of the precursor to the sacrificial pore-forming material is 2-3:1; The etchant is acetic acid; the volume ratio of N,N-dimethylformamide to the etchant is 4-5:1; The target temperature of the high temperature heating is 140°C-180°C, and the target temperature is heated within 15 minutes, and the heating time is 1-1.5 hours.

2. The preparation method according to claim 1, characterized in that: The iron metal salt is ferric chloride, and the zinc metal salt is zinc chloride.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the precursor to tungsten hexacarbonyl is 1:1.5-2.

4. An ultra-thin palladium-tin nanonet catalyst, characterized in that: The ultrathin palladium tin nanonet catalyst is prepared by the preparation method according to any one of claims 1 to 3, and its electrochemical active area is 55-60 m 2 / g Pd , with an ultra-thin structure with a thickness of less than 1 nm.

5. Use of the ultrathin palladium tin nanomesh catalyst according to claim 4 in direct ethanol fuel cells or electrocatalytic ethanol oxidation.

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