Silver modified Anderson type polyacid catalyst electrode material and preparation method thereof

Abstract

The invention is applicable to the technical field of electrocatalytic materials, and provides a silver modified Anderson type polyacid catalyst electrode material and a preparation method thereof, the electrode material is composed of a transition metal silver element, Anderson type polyoxometallate (polyacid for short), a conductive agent and carbon cloth; the silver-modified Anderson type polyacid catalyst is used as a catalytic activity center of the electrode material, and the general formula of the silver-modified Anderson type polyacid catalyst is Mx [Ar-CH = CH-Ar] y [(CrMo6O24H6], wherein M is Ag, Cu, Co or Ni, and x is equal to 0-3; ar is thiophene, pyrrole, pyridine or imidazole, and y is equal to 0-3. By constructing the Ag-modified Anderson type polyacid catalyst with a clear molecular structure, the problems of poor electrocatalysis effect, difficulty in recovery and the like of polyacid in the field of electrocatalysis are solved, and meanwhile, excellent cycling stability is shown. An important reference is provided for revealing a relationship between a catalyst structure and catalytic performance, and a new thought is provided for the field of electro-catalytic synthesis of sulfoxide.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials technology, and particularly relates to a silver-modified Anderson-type polyacid catalyst electrode material and its preparation method. Background Technology

[0002] Sulfur oxides (SO₄) released from the combustion of sulfur-containing fuels x Aromatic sulfur is a major air pollutant, not only a primary cause of environmental events such as acid rain and photochemical smog, but also significantly linked to the greenhouse effect. Among numerous emerging desulfurization technologies, electrocatalytic oxidative desulfurization (EODS) has attracted considerable attention and become a research hotspot in recent years due to its ability to effectively remove aromatic sulfur components from fuel oil. The oxidation reaction of methyl phenyl sulfide (MPS) serves as a typical oxidative desulfurization reaction model, producing methyl phenyl sulfoxide (MPS) and methyl phenyl sulfone (MPS). MPS is an important pharmaceutical intermediate; the market size of omeprazole enteric-coated tablets synthesized from MPS is projected to reach $7.2 billion by 2027 (according to IQVIA forecasts). Therefore, improving the selectivity of methyl phenyl sulfide oxidation to sulfoxide synthesis is of great significance.

[0003] Catalysts are one of the decisive factors affecting the selectivity of sulfoxides. Therefore, researchers have been dedicated to developing highly efficient catalysts to improve the selectivity of sulfoxides. Polyoxometalates (also known as polyacids) play an important role in oxidative desulfurization reactions due to their unique redox properties and well-defined structures. However, in the field of electrocatalytic desulfurization, polyacids still face problems such as poor conductivity, unsatisfactory electrocatalytic effect, and low selectivity.

[0004] Silver-based composite materials, as catalysts, possess advantages such as high stability, low toxicity, and strong resistance to deactivation, maintaining high Faradaic efficiency even after long-term operation. Based on this, it is speculated that silver-modified polyacids hold promise for significantly improving electrocatalytic desulfurization. To date, the application of silver-based polyacids in the electrocatalytic synthesis of sulfoxides has not attracted much attention. Summary of the Invention

[0005] The purpose of this invention is to provide a silver-modified Anderson-type polyacid catalyst electrode material and its preparation method, aiming to solve the problems mentioned in the background art.

[0006] This invention is implemented as follows: a silver-modified Anderson-type polyoxometalate catalyst electrode material, wherein the electrode material is composed of transition metal silver, Anderson-type polyoxometalates (POMs), a conductive agent, and carbon cloth; the silver-modified Anderson-type polyoxometalate catalyst serves as the catalytic active center of the electrode material, with the general formula M. x [Ar-CH=CH-Ar] y[(CrMo6O 24 H6];

[0007] Where M is Ag, Cu, Co or Ni, x = 0 to 3; Ar is thiophene, pyrrole, pyridine or imidazole, y = 0 to 3.

[0008] A further technical solution is to use Ag when x = 3 and y = 0. + The ions form a unique three-dimensional open framework structure with the anions of Anderson-type polyacid salts through coordination bonds;

[0009] Its cell parameters are: α=111.5130(10)°, β=96.7720(10)°, γ=91.8030(10)°.

[0010] A further technical solution is that the transition metal silver element is Ag + The ions exist in the form of coordination bonds with Anderson-type polyoxometalates, including but not limited to Na3(CrMo6O) 24 H6)·8H2O, the conductive material includes, but is not limited to, acetylene black, and the carbon cloth includes, but is not limited to, hydrophilic carbon cloth.

[0011] Another objective of this invention is to provide a method for preparing a silver-modified Anderson-type polyacid catalyst electrode material. Based on the aforementioned silver-modified Anderson-type polyacid electrode material, the preparation process includes the following steps:

[0012] Step 1: Add distilled water to beakers A and B respectively. Dissolve Na3(CrMo6O) in beaker A. 24 H6)·8H2O; Add a certain molar ratio of soluble inorganic metal salt and pyridine ligand to beaker B, then mix the solutions in the two beakers, and adjust the pH of the mixed solution with a certain concentration of nitric acid solution; continue stirring for a period of time, transfer the mixed solution to a polytetrafluoroethylene-lined autoclave, and then place it in an oven for a period of time; finally, remove the autoclave, separate the product, wash, and dry to obtain a crystalline substance with a specific morphology, which is the Anderson-type polyacid catalyst.

[0013] Step 2: Soak commercially available carbon cloth (CC) in 2M HCl solution and boil it to ensure surface cleanliness; under ultrasonic conditions, disperse the obtained catalyst and conductive agent in a mixed solvent of isopropanol and water containing 5wt% Nafion to prepare a suspension; spray the suspension onto the surface of the carbon cloth and dry it at room temperature to obtain catalyst-modified carbon cloth.

[0014] A further technical solution is that, in step 1, Na3(CrMo6O) 24The molar ratio of H6)·8H2O, soluble inorganic metal salt, and pyridine ligand is 1:10:10 to 5:10:10; the soluble inorganic metal salt is one or two of nitrate, sulfate, and acetate.

[0015] In a further technical solution, in step 1, the concentration of the nitric acid solution used is 0.1–2 mol / L, the pH range of the mixed solution is 1–5, the stirring time is 1–3 h, the reaction temperature is 60–180 °C, and the heating time is 24–120 h.

[0016] In a further technical solution, in step 2, the carbon cloth includes hydrophilic carbon cloth or hydrophobic carbon cloth, and the conductive agent includes one or two of acetylene black, graphene, carbon nanotubes, and carbon dots; the catalyst mass is 0.1-10 mg, the isopropanol volume is 100-900 μL, the deionized water volume is 100-900 μL, and the suspension volume is 1-100 μL.

[0017] Another objective of this invention is to provide an application of a silver-modified Anderson-type polyacid catalyst electrode material, which is used in the electrocatalytic synthesis of sulfoxides based on the aforementioned silver-modified Anderson-type polyacid catalyst electrode material.

[0018] The present invention provides a silver-modified Anderson-type polyacid catalyst electrode material and its preparation method, the beneficial effects of which are as follows:

[0019] (1) Several novel compounds were successfully prepared by hydrothermal synthesis, mainly classified into the following three categories: Ag-modified CrMo6-type polyacids; CrMo6-type polyacids co-modified by different transition metals (Ag, Cu, Co, Ni) and organic ligands (Ar-CH=CH-Ar); and Mo8-type polyacids modified by a single organic ligand (1,2-bis(4-pyridyl)ethylene, abbreviated as bpe). The crystal structure was clarified by single-crystal X-ray diffraction analysis, and the consistency between the crystal structure and the single-crystal analysis results was further verified by various characterization methods such as infrared spectroscopy (IR), powder X-ray diffraction (PXRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS).

[0020] (2) When the above seven compounds were applied to the electrocatalytic synthesis of sulfoxides at room temperature, Ag3CrMo6 compounds exhibited excellent catalytic performance, with methyl phenyl sulfide (MPS) conversion, sulfoxide selectivity, and Faradaic efficiency reaching 100%, 95%, and 96%, respectively. In contrast, the synthesized non-silver transition metal modified Anderson-type polyacid catalyst showed relatively low electrocatalytic performance, further illustrating the key role of Ag modification in improving sulfoxide selectivity. The developed silver-modified Anderson-type polyacid catalyst provides a new approach for the field of electrocatalytic desulfurization.

[0021] (3) This method uses inexpensive chemical sulfide as a raw material and water as an oxygen source. It utilizes electrical energy to drive the transfer of oxygen atoms from water molecules to sulfide molecules, thereby achieving the efficient and green synthesis of sulfoxide. This method has the advantages of mild reaction conditions and does not require the use of traditional oxidants such as hydrogen peroxide or ozone, significantly improving safety and environmental friendliness. It aligns with the concept of sustainable development and is beneficial to ecological environmental protection. Therefore, it has high market promotion value and broad application prospects. Attached Figure Description

[0022] Figure 1 In the diagrams, af represents the polyhedral ball-and-stick diagram of Example 1 (Ag3CrMo6) and two Ag... + Coordination modes of ions, coordination modes of Ag1, coordination modes of Ag2, 2D planar structures, and 3D packing diagrams;

[0023] Figure 2 Crystal structure diagrams of Example 2 and comparative materials 1-5;

[0024] Figure 3 The PXRD spectra of seven compounds are shown.

[0025] Figure 4 Scanning electron microscope images of Ag3CrMo6 before and after the reaction;

[0026] Figure 5 High-resolution transmission electron microscope images of Ag3CrMo6 before and after the reaction;

[0027] Figure 6 A comparison chart of the performance of seven compounds in the electrocatalytic synthesis of sulfoxides;

[0028] Figure 7 The mass spectrum of the electrocatalytic synthesis of sulfoxide products;

[0029] Figure 8 In the figure, a and b are the cycle stability test results of Ag3CrMo6 / CC as an electrocatalyst and their PXRD patterns before and after the electrocatalytic reaction, respectively. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0032] One embodiment of the present invention provides a silver-modified Anderson-type polyoxometalate catalyst electrode material, wherein the electrode material is composed of transition metal silver, Anderson-type polyoxometalates (POMs), a conductive agent, and carbon cloth; the silver-modified Anderson-type polyoxometalate catalyst serves as the catalytic active center of the electrode material, and has the general formula M. x [Ar-CH=CH-Ar] y [(CrMo6O 24 H6];

[0033] Where M is Ag, Cu, Co or Ni, x = 0 to 3; Ar is thiophene, pyrrole, pyridine or imidazole, y = 0 to 3.

[0034] When x = 3 and y = 0, Ag + The ions form a unique three-dimensional open framework structure with the anions of Anderson-type polyacid salts through coordination bonds; its cell parameters are: α=111.5130(10)°, β=96.7720(10)°, γ=91.8030(10)°.

[0035] In a preferred embodiment of the present invention, the transition metal silver element is Ag + The ions exist in the form of coordination bonds with Anderson-type polyoxometalates, including but not limited to Na3(CrMo6O) 24 H6)·8H2O, the conductive material includes, but is not limited to, acetylene black, and the carbon cloth includes, but is not limited to, hydrophilic carbon cloth.

[0036] Another embodiment of the present invention provides a method for preparing a silver-modified Anderson-type polyacid electrode material, which, based on the above-mentioned silver-modified Anderson-type polyacid electrode material, includes the following steps:

[0037] Step (1): Add distilled water to beakers A and B respectively. Dissolve Na3(CrMo6O) in beaker A. 24H6)·8H2O; Add a certain molar ratio of soluble inorganic metal salt and pyridine ligand to beaker B, then mix the solutions in the two beakers, and adjust the pH of the mixed solution with a certain concentration of nitric acid solution; continue stirring for a period of time, transfer the mixed solution to a polytetrafluoroethylene-lined autoclave, and then place it in an oven for a period of time; finally, remove the autoclave, separate the product, wash, and dry to obtain a crystalline substance with a specific morphology, which is the Anderson-type polyacid catalyst.

[0038] Step (2): Soak commercially available carbon cloth (CC) in 2M HCl solution and boil it to ensure the surface is clean; under ultrasonic conditions, disperse the obtained catalyst and conductive agent in a mixed solvent of isopropanol and water containing 5wt% Nafion to prepare a suspension; spray the suspension onto the surface of the carbon cloth and dry it at room temperature to obtain catalyst-modified carbon cloth.

[0039] In a preferred embodiment of the present invention, in step 1, Na3(CrMo6O) 24 The molar ratio of H6)·8H2O, soluble inorganic metal salt, and pyridine ligand is 1:10:10 to 5:10:10; the soluble inorganic metal salt is one or two of nitrate, sulfate, and acetate.

[0040] In a preferred embodiment of the present invention, in step 1, the concentration of the nitric acid solution used is 0.1–2 mol / L, the pH range of the mixed solution is 1–5, the stirring time is 1–3 h, the reaction temperature is 60–180 °C, and the heating time is 24–120 h.

[0041] In a preferred embodiment of the present invention, in step 2, the carbon cloth includes hydrophilic carbon cloth or hydrophobic carbon cloth, and the conductive agent includes one or two of acetylene black, graphene, carbon nanotubes, and carbon dots; the catalyst mass is 0.1-10 mg, the isopropanol volume is 100-900 μL, the deionized water volume is 100-900 μL, and the suspension volume is 1-100 μL.

[0042] Several specific embodiments are provided below to verify the effectiveness of this method.

[0043] Example 1: When M = Ag, x = 3, y = 0, and Ar = imidazole, {(Ag(H2O))2Ag(CrMo6O)} 18 The synthesis of (OH)6)}n (abbreviated as Ag3CrMo6) and the preparation method of electrode materials are as follows:

[0044] Step (1), Synthesis of Ag3CrMo6: Take beaker A and beaker B respectively. Add 10mL of water to beaker A and dissolve Na3(CrMo6O) in the water. 24H6)·8H2O (0.4185 g, 0.34 mmol). 20 mL of water was added to beaker B, followed by AgNO3 (0.1699 g, 1 mmol) under stirring. After dissolution, imidazole-4,5-dicarboxylic acid (0.1561 g, 1 mmol) was added. After stirring for 30 min, the solutions in beakers A and B were mixed, and the pH of the mixed solution was measured to be 2. After stirring for another 30 min, the mixed solution was transferred to a polytetrafluoroethylene-lined reactor and heated at 160 °C for 2 days to obtain purple-pink block crystals. The product was washed with deionized water and dried in an oven at 60 °C, with a yield of approximately 72%.

[0045] Step (2), Electrode Material Preparation: Commercially available carbon cloth (CC) was immersed in 2M HCl solution and boiled for 15 min to ensure surface cleanliness. Under ultrasonic conditions, the catalyst (8 mg) obtained in Step 1 and acetylene black (2 mg) were dispersed in a mixed solvent containing 5 wt% Nafion in isopropanol (560 μL) and water (400 μL). 400 μL of this suspension was sprayed onto a 1 cm... 2 The surface of the carbon cloth was dried at room temperature to obtain catalyst-modified carbon cloth (Ag3CrMo6 / CC).

[0046] Example 2: When M = Ag, x = 1, y = 1, and Ar = pyridine, {(H2bpe)(Ag(CrMo6O)} 24 The synthesis of H6))}n (abbreviated as CrMo6-Ag-bpe) and the preparation method of electrode materials are as follows:

[0047] Step (1), Synthesis of CrMo6-Ag-bpe: The catalyst was prepared in the same manner as in Example 1, except that imidazole-4,5-dicarboxylic acid was replaced with bpe (0.0740 g, 0.4 mmol), and triethylamine (20 μL) and ammonium metavanadate (18 mg) were added to it. The pH of the mixed solution was adjusted to 5. The final product was represented as CrMo6-Ag-bpe.

[0048] Step (2), Electrode material preparation: Similar to the electrode material preparation method in Example 1, except that the catalyst obtained in Example 1 is replaced with CrMo6-Ag-bpe.

[0049] Comparative Example 1: When M = Cu, x = 1, y = 1, and Ar = pyridine, {(bpe)H[Cu(H2O)2(CrMo6O)] 18 The synthesis of (OH)6)]·4H2O}n (abbreviated as CrMo6-Cu-bpe) and the preparation method of electrode materials are as follows:

[0050] Step (1), Synthesis of CrMo6-Ag-bpe: The catalyst was prepared in the same manner as in Example 1, except that AgNO3 was replaced with Cu(NO3)2·3H2O (0.1876 g, 1 mmol), imidazole-4,5-dicarboxylic acid was replaced with bpe (0.0740 g, 0.4 mmol), and triethylamine (20 μL) and ammonium metavanadate (18 mg) were added to it. The pH of the mixed solution was adjusted to 5. The final product was named CrMo6-Cu-bpe.

[0051] Step (2), Electrode material preparation: Similar to the electrode material preparation method in Example 1, except that the catalyst obtained in Example 1 is replaced with CrMo6-Cu-bpe.

[0052] Comparative Example 2: When M = Co, x = 1, y = 1, and Ar = pyridine, {(H2bpe)(Co(CrMo6O)} 24 The synthesis of H6))}n (abbreviated as CrMo6-Co-bpe) and the preparation method of electrode materials are as follows:

[0053] Step (1), Synthesis of CrMo6-Co-bpe: The catalyst was prepared in the same way as in Example 1, except that AgNO3 was replaced with Co(NO3)2·6H2O (0.1746g, 0.6mmol), imidazole-4,5-dicarboxylic acid was replaced with bpe (0.0740g, 0.4mmol), and triethylamine (20μL) and ammonium metavanadate (18mg) were added to it. The pH of the mixed solution was adjusted to 5. The final product was named CrMo6-Co-bpe.

[0054] Step (2), Electrode material preparation: Similar to the electrode material preparation method in Example 1, except that the catalyst obtained in Example 1 is replaced with CrMo6-Co-bpe.

[0055] Comparative Example 3: When M = Cu, x = 1, y = 3, and Ar = pyridine, bpe[Cu(bpe)2(H2O)2(CrMo6O 18 The synthesis of (OH)6)2]·7H2O (abbreviated as CrMo6-Cu-bpe-2) and the preparation method of electrode materials are as follows:

[0056] Step (1), Synthesis of CrMo6-Cu-bpe-2: The catalyst was prepared in the same way as in Example 1, except that AgNO3 was replaced with Cu(NO3)2·3H2O (0.1122g, 0.6mmol), imidazole-4,5-dicarboxylic acid was replaced with bpe (0.0740g, 0.4mmol), and triethylamine (20μL) and ammonium metavanadate (18mg) were added to it. The pH of the mixed solution was adjusted to 5. The final product was named CrMo6-Cu-bpe-2.

[0057] Step (2), Electrode material preparation: Similar to the electrode material preparation method in Example 1, except that the catalyst obtained in Example 1 is replaced with CrMo6-Cu-bpe-2.

[0058] Comparative Example 4: When M = Ni, x = 1, y = 3, and Ar = pyridine, bpe[Ni(bpe)2(H2O)2(CrMo6O 18 The synthesis of [(OH)6)2]·14H2O (abbreviated as CrMo6-Ni-bpe) and the preparation method of electrode materials are as follows:

[0059] Step (1), Synthesis of CrMo6-Ni-bpe: The catalyst was prepared in the same way as in Example 1, except that AgNO3 was replaced with Ni(NO3)2·6H2O (0.1746g, 0.6mmol), imidazole-4,5-dicarboxylic acid was replaced with bpe (0.0740g, 0.4mmol), and triethylamine (20μL) and ammonium metavanadate (18mg) were added to it. The pH of the mixed solution was adjusted to 4. The final product was named CrMo6-Ni-bpe.

[0060] Step (2), Electrode material preparation: Similar to the electrode material preparation method in Example 1, except that the catalyst obtained in Example 1 is replaced with CrMo6-Ni-bpe.

[0061] Comparative Example 5: When x = 0, y = 4, and Ar = pyridine, (Hbpe)2[(Hbpe)2(Mo8O 26 Synthesis of 4H2O (abbreviated as Mo8-bpe) and preparation method of electrode materials

[0062] Step (1), synthesis of Mo8-bpe: The catalyst was prepared in the same way as in Example 1, except that AgNO3 was not added, imidazole-4,5-dicarboxylic acid was replaced with bpe (0.0740 g, 0.4 mmol), the pH of the mixed solution was adjusted to 5, and the final product was denoted as Mo8-bpe.

[0063] Step (2), Electrode material preparation: Similar to the electrode material preparation method in Example 1, except that the catalyst obtained in Example 1 is replaced with Mo8-bpe.

[0064] Comparative Example 6: Preparation of CC electrode materials;

[0065] Similar to the electrode material preparation method in Example 1, the difference is that no slurry was sprayed onto the CC.

[0066] Comparative Example 7: Preparation of acetylene black electrode material;

[0067] The preparation method is similar to that of the electrode material in Example 1, except that only acetylene black is used as the active material.

[0068] The crystallographic data of Examples 1, 2 and Comparative Examples 1-5 are shown in Tables 1 and 2 below.

[0069] Table 1. Crystallographic data of Examples 1, 2 and Comparative Example 1

[0070]

[0071] a R1=∑||F o |-|F c || / ∑|F o |, b wR 2 =∑[w(F o 2 -F c 2 ) 2 ] / ∑[w(F o 2 ) 2 ] 1 / 2 Table 2 Crystallographic data for Comparative Examples 2-5

[0072]

[0073]

[0074] a R1=∑||F o |-|F c || / ∑|F o |, b wR 2 =∑[w(F o 2 -F c 2 ) 2 ] / ∑[w(F o 2 ) 2] 1 / 2

[0075] The electrode materials prepared in Examples 1, 2, and Comparative Examples 1 to 7 were applied to the electrocatalytic synthesis of sulfoxide. The catalytic experimental procedures for all electrocatalytic synthesis of sulfoxide were identical; the specific experimental procedures are detailed below using Example 1 as an example.

[0076] Electrocatalytic synthesis of sulfoxide was carried out using a three-electrode system, in which Ag3CrMo6 / CC (1cm) was used. 2 A platinum sheet is used as the counter electrode, and Ag / Ag is used as the working electrode. + The electrode served as a reference electrode. Electrolysis experiments were conducted in an electrolytic cell using a constant potential electrolysis method. Before the experiment, 10 cyclic voltammetric (CV) scans were performed at a scan rate of 20 mV·s. -1 The scan range was 0–1.2 V. Subsequently, MPS (0.5 mmol), dodecane (0.6 mmol), acetic acid-water solution (CH3COCH3 / H2O, 25.0 mL, volume ratio 23:2), and LiClO4 (1.0 mmol) were added to the system, and the scan was performed at 1.0 V vs. Ag / Ag. + Electrolysis was performed at a constant potential for 5 hours. For cycle stability testing, the Ag3CrMo6 / CC electrode was washed multiple times with acetone and ethanol after each cycle and dried in air before use in the next cycle.

[0077] After the electrocatalytic reaction was completed, 1 μL of the reaction solution was taken for qualitative analysis by gas chromatography (GC). The analytical conditions were as follows: the column temperature was initially set at 60 °C and held for 2 min, then increased to 100 °C at a rate of 5 °C / min and held for 1 min, and then increased to 125 °C at a rate of 1 °C / min and held for 0.1 min.

[0078] Table 3 shows a comparison of the electrocatalytic synthesis performance of sulfoxides in Comparative Examples 1-7 with those in Examples 1 and 2. The experimental results indicate that Example 1 (Ag3CrMo6 / CC) exhibits the best sulfoxide selectivity compared to Example 2 and Comparative Examples 1-7. After electrolysis at 1.0 V for 10 h at room temperature, the sulfoxide selectivity and Faradaic efficiency reached 95% and 96%, respectively. After six cycles, the catalyst maintained a selectivity and Faradaic efficiency of over 90%, demonstrating good stability and reusability.

[0079] Table 3. Performance comparison of electrocatalytic synthesis of sulfoxide in Examples 1, 2 and Comparative Examples 1-7

[0080]

[0081] Depend on Figure 1It can be seen that there are two crystallographically independent Ag types in Ag3CrMo6. + The ions are Ag1 and Ag2, both exhibiting a six-coordinate mode. Ag1 coordinates not only with the adjacent polyacid unit but also with a water molecule (H2O). In this structure, each Anderson-type anion [Cr(OH)6Mo6O]... 18 ] 3- As a dodecanotic chelate ligand, it interacts with Ag via the terminal O atom and the bridging O atom. + Ion coordination. These [Cr(OH)6Mo6O 18 ] 3- Anionic clusters are first linked by Ag-O bonds to form one-dimensional chains. Each chain is then further connected to two parallel chains via Ag-O-Mo bonds, thus constructing a window-like two-dimensional layered structure. This structure is composed of polymetallic oxy-ion cluster anions and Ag... + Such a two-dimensional layered structure composed of ions is quite rare. Furthermore, these two-dimensional sheets are further connected by another type of six-coordinated silver ion (Ag2), forming a three-dimensional open framework.

[0082] Figure 2 The crystal structure diagrams are for Example 2 and Comparative Materials 1-5. Figure 2 (a)-(f) are CrMo6-Ag-bpe, CrMo6-Co-bpe, CrMo6-Cu-bpe, CrMo6-Cu-bpe-2, CrMo6-Ni-bpe, and Mo8-bpe.

[0083] Figure 3 The PXRD patterns of seven compounds are shown. Figure 3 (a)-(g) correspond to Ag3CrMo6, CrMo6-Ag-bpe, CrMo6-Cu-bpe, CrMo6-Co-bpe, CrMo6-Cu-bpe-2, CrMo6-Ni-bpe, and Mo8-bpe, respectively. PXRD analysis shows that the measured peak positions of the crystals are basically consistent with the simulated peak positions, proving that the prepared compound is a pure phase and further demonstrating the successful preparation of the compound.

[0084] Figure 4 These are scanning electron microscope images of Ag3CrMo6 before and after the reaction. Before the reaction, the Ag3CrMo6 catalyst exhibits a nanosphere morphology on CC. After the electrocatalytic reaction, the catalyst morphology remains essentially unchanged, and no Ag element aggregation occurs, demonstrating that the synthesized catalyst has good stability.

[0085] Figure 5These are high-resolution transmission electron microscope (TEM) images of Ag3CrMo6 before and after the reaction. No lattice fringes of elemental Ag were observed in the Ag3CrMo6 catalyst before or after the reaction. Combined with EDS analysis, the catalyst showed a uniform distribution of elements after the reaction, indicating that no elemental Ag was generated during the electrocatalytic reaction, further demonstrating the excellent stability of the Ag3CrMo6 catalyst in electrocatalytic reactions.

[0086] Figure 6 The table presents a performance comparison of seven compounds in the electrocatalytic synthesis of sulfoxide. Analysis of the data in Table 3 shows that Ag3CrMo6 exhibits the best catalytic effect compared to other comparative materials, with conversion, selectivity, and Faraday efficiency reaching 100%, 95%, and 96%, respectively. This demonstrates that introducing the transition metal Ag into Anderson-type polyacids can significantly improve the desulfurization effect of electrocatalytic MPS. It is further speculated that the active site for electrocatalytic MPS oxidative desulfurization may be located on Ag. A comparison of the Ag coordination environments in Ag3CrMo6 and CrMo6-Ag-bpe catalysts reveals that the Ag3CrMo6 crystal structure contains two different silver coordination environments: Ag1 (coordinated with one water molecule and four adjacent polyacids) and Ag2 (coordinated only with four adjacent polyacids). In contrast, CrMo6-Ag-bpe contains only one coordination environment, Ag2. Previous studies have shown that metals with active oxygen are usually catalytically active sites. Combined with experimental results, Ag1 in Ag3CrMo6 is the catalytically active site in the electrocatalytic MPS oxidation reaction.

[0087] Figure 7 This is the mass spectrum of the sulfoxide product synthesized by electrocatalysis. A characteristic peak of methylphenyl sulfoxide appeared at m / z = 140.0, further verifying the successful conversion of MPS to methylphenyl sulfoxide.

[0088] Figure 8 Figures a and b in the figure show the cyclic stability test results of Ag3CrMo6 / CC as an electrocatalyst and the PXRD patterns before and after the electrocatalytic reaction, respectively. Using Ag3CrMo6 / CC as a catalyst, in a standard electrocatalytic system, after six cycles of stability testing, the catalyst still maintained a selectivity and conversion rate of over 90%. PXRD tests on the catalyst before and after cycling showed that the crystal structure of Ag3CrMo6 / CC remained stable after six cycles, demonstrating the excellent cyclic stability of this catalyst.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A silver-modified Anderson-type polyacid catalyst electrode material, characterized in that, The electrode material is composed of a transition metal silver element, an Anderson type polyoxometalate, a conductive agent and a carbon cloth; the silver modified Anderson type polyacid catalyst serves as a catalytic active center of the electrode material, and the general formula is M x [Ar-CH=CH-Ar] y [(CrMo6O 24 H6] Wherein, M is Ag, Cu, Co or Ni, x = 0-3; Ar is thiophene, pyrrole, pyridine or imidazole, y = 0-3. 2.The silver-modified Anderson-type polyacid catalyst electrode material of claim 1, wherein, Ag when x = 3, y = 0 + The ions form a three-dimensional open framework structure with the anions of the Anderson-type polyacid salt through coordination bonds; The cell parameters are: alpha = 111.5130(10) °, beta = 96.7720(10) °, gamma = 91.8030(10) °. 3.The silver-modified Anderson-type polyacid catalyst electrode material of claim 1, wherein, The transition metal silver element is Ag + The ions exist in the form of coordination with the anions of the Anderson-type polyoxometalate, which is Na3(CrMo6O 24 H6)·8H2O.

4. A method for preparing a silver-modified Anderson-type polyacid catalyst electrode material, based on the silver-modified Anderson-type polyacid catalyst electrode material according to any one of claims 1 to 3, characterized in that The preparation process comprises the following steps: Step 1: Distilled water was added to two beakers, A and B, respectively. In the beaker A, Na3(CrMo6O 24 H6)·8H2O was dissolved; in the beaker B, a soluble inorganic metal salt and a pyridine ligand were added, and then the solutions in the two beakers were mixed, and the pH value of the mixed solution was adjusted with a nitric acid solution; after continuous stirring, the mixed solution was transferred to a polytetrafluoroethylene-lined autoclave, which was then placed in an oven for heating; finally, the autoclave was taken out, the product was separated, washed, and dried to obtain a crystalline material with a specific morphology, i.e., an Anderson-type polyacid catalyst; Step 2: carbon cloth is immersed in 2M HCl solution and boiled to ensure surface cleaning; under ultrasonic conditions, the obtained Anderson-type polyacid catalyst and conductive agent are dispersed in a mixed solvent of isopropanol and deionized water containing 5wt% Nafion to prepare a suspension; the suspension is sprayed on the surface of the carbon cloth, and dried at room temperature to obtain a catalyst modified carbon cloth.

5. The method for preparing silver-modified Anderson-type polyacid catalyst electrode material according to claim 4, characterized in that, In the step 1, Na3(CrMo6O 24 The molar ratio of H6)·8H2O, soluble inorganic metal salt and pyridine ligand is 1:10:10-5:10:10; the soluble inorganic metal salt is one or two of nitrate, sulfate and acetate.

6. The method for preparing silver-modified Anderson-type polyacid catalyst electrode material according to claim 4, characterized in that, In the step 1, the concentration of the used nitric acid solution is 0.1-2mol / L, the pH range of the mixed solution is 1-5; the stirring time is 1-3h, the heating temperature is 60-180℃, and the heating time is 24-120h.

7. The method for preparing silver-modified Anderson-type polyacid catalyst electrode material according to claim 4, characterized in that, In the step 2, the carbon cloth includes hydrophilic carbon cloth or hydrophobic carbon cloth, the conductive agent includes one or two of acetylene black, graphene, carbon nanotube and carbon dot; the catalyst mass is 0.1-10mg, the isopropanol volume is 100-900μL, the deionized water volume is 100-900μL, and the suspension volume is 1-100μL.

8. Use of a silver-modified Anderson-type polyacid catalyst electrode material, based on the silver-modified Anderson-type polyacid catalyst electrode material according to any one of claims 1 to 3, characterized in that The electrode material is applied to electrocatalytic synthesis of sulfoxides.

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