Catalyst as well as preparation method and application thereof

Abstract

The invention relates to a catalyst and a preparation method and application thereof, and belongs to the technical field of electrocatalysis, the method comprises the following steps: dissolving 1, 2, 4-triazole, a silver source and phosphomolybdic acid in a first solvent, and then complexing to obtain an emulsion containing a PMoA (at) C-N-Ag < + > complexing structure; dissolving a carrier in a second solvent to obtain a carrier solution; and mixing the carrier solution with the emulsion containing the PMoA-coated C-N-Ag < + > complexing structure, and then carrying out in-situ reduction treatment to obtain the catalyst, a (MoOX) / Ag heterogeneous nano-catalyst loaded on a carrier is formed by constructing a PMoA (at) C-N-Ag < + > complexing structure and then performing in-situ reduction conversion. The catalytic intrinsic activity of phosphomolybdic acid is utilized, and PMoA is coated with metal Ag with good conductivity, so that electrode dissolution is slowed down, and the conductivity of the electrode is ensured.

Description

Technical Field

[0001] This application relates to the field of electrocatalytic technology, and particularly relates to a catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] The process of electrochemically splitting water to produce hydrogen includes a hydrogen evolution reaction (HER) at the cathode and an oxygen evolution reaction (OER) at the anode. Since overcoming the energy barrier of the anode oxygen evolution reaction (OER) requires a relatively high overpotential, matching an anodic oxidation reaction that is easier to occur than OER for the cathode hydrogen evolution reaction (HER), such as the oxidation of small molecules like methanol, ethanol, glycerol, etc., is an important means to promote the efficiency of electrolytic water hydrogen production. The catalytic potential of the composite material of molybdenum oxide MoO x and metal in the electrocatalytic oxidation of organic small molecules has been somewhat confirmed.

[0003] Benefiting from the regulation of the outer electron structure of active metal atoms, composite materials usually have more excellent catalytic performance compared with single metal materials. In such catalysts, the regulating effect usually comes from the doped second metal. The doped metal has electronic and geometric effects on the active metal atom sites, thereby improving its catalytic activity. In addition to traditional second metal doping, new dopants such as organic polymers, organometallic complexes, and polyoxometalates have also attracted more and more attention. For example, it has been proposed to dope an organic dye (Congo red) in silver (Ag) to achieve high catalytic activity for methanol oxidation; high catalytic activity for styrene hydrogenation has been achieved by wrapping rhodium(I) complex with Ag. In addition, a heterogeneous acid catalyst with H3PMo 12 O 40 wrapped in a silver metal matrix shows stronger catalytic performance for the alkylation reaction of aromatic hydrocarbons. In these catalysts, polyoxometalates (POMs) can be used alone as acidic catalysts or as dopants to regulate the catalytic ability of active metals.

[0004] Phosphomolybdic acid (H3PMo 12 O 40, H3PO4·12MoO3, phosphomolybdic acid (hereinafter referred to as PMoA), is a typical heteropolyacid with a Keggin structure. One P atom serves as the center, surrounded by 12 octahedral MoO6 structural units. Phosphomolybdic acid PMoA has 36 oxygen atoms exposed on the surface, and has fast multi-electron reversible redox characteristics under relatively mild conditions. It is an important and efficient oxidation catalyst commonly used in thermal catalytic reactions, and is widely used in organic synthesis, organic matter oxidation, and non-carbon fuel cells. At the same time, phosphomolybdic acid PMoA can be used as a doping component in metal catalysts, which can affect the electron distribution of active metals and can also participate in the intermediate reactions of oxygen activation and transfer, thereby changing the catalytic performance of metal catalysts. However, phosphomolybdic acid PMoA is extremely soluble in water and has poor conductivity, so it is difficult to be applied in electrolytic water catalysis. Summary of the Invention

[0005] The inventors found that phosphomolybdic acid PMoA can be anchored by metal atoms, so these anchored metal atoms can be used as seeds for further deposition of metal atoms, thereby obtaining a catalyst with a core@shell heterogeneous composite structure in which phosphomolybdic acid PMoA molecules are in the core and metals are in the shell.

[0006] This application provides a catalyst, its preparation method and application to improve the problem of poor conductivity of phosphomolybdic acid.

[0007] In a first aspect, this application provides a preparation method of a catalyst, and the method includes:

[0008] Dissolve 1,2,4-triazole, a silver source and phosphomolybdic acid in a first solvent, and then carry out complexation to obtain an emulsion containing a PMoA@C-N-Ag + complexation structure;

[0009] Dissolve the carrier in a second solvent to obtain a carrier solution;

[0010] Mix the carrier solution and the emulsion containing the PMoA@C-N-Ag + complexation structure, and then carry out in-situ reduction treatment to obtain a catalyst.

[0011] As an optional implementation manner, the silver source includes silver acetate.

[0012] As an optional implementation manner, the first solvent includes ethylene glycol.

[0013] As an optional implementation manner, the molar ratio of 1,2,4-triazole, the silver source and phosphomolybdic acid is (1-3):(0.5-1.5):(0.1-0.3).

[0014] As an alternative embodiment, the molar ratio of the 1,2,4-triazole, the silver source and the phosphomolybdic acid is (1.5 to 2.5):(0.8 to 1.2):(0.15 to 0.25).

[0015] As an alternative embodiment, the complexing environment is normal temperature and pressure, and the complexing time is 40 to 56 hours.

[0016] As an alternative embodiment, the complexing time is 44 to 52 hours.

[0017] As an alternative embodiment, the mass of the carrier is 20% to 30% of the mass of all the metals in the PMoA@C-N-Ag + complexing structure.

[0018] As an alternative embodiment, the mass of the carrier is 23% to 27% of the mass of all the metals in the PMoA@C-N-Ag + complexing structure.

[0019] As an alternative embodiment, the mass concentration of the carrier in the carrier solution is 0.003 to 0.005 g / mL.

[0020] As an alternative embodiment, the carrier includes carbon black.

[0021] As an alternative embodiment, the carbon black includes vulcan XC-72.

[0022] As an alternative embodiment, the second solvent includes ethylene glycol.

[0023] As an alternative embodiment, the temperature of the in-situ reduction treatment is 130 to 230 °C; and / or

[0024] the time of the in-situ reduction treatment is 1 to 3 hours.

[0025] As an alternative embodiment, the temperature of the in-situ reduction treatment is 160 to 200 °C; and / or

[0026] the time of the in-situ reduction treatment is 1.5 to 2.5 hours.

[0027] As an alternative embodiment, the method further includes: cleaning the catalyst.

[0028] In a second aspect, the present application provides a catalyst, which is prepared by using the catalyst preparation method described in the first aspect.

[0029] As an alternative embodiment, the particle size of the catalyst is 11 to 16 nm.

[0030] As an alternative embodiment, the catalyst comprises a support and a catalyst body attached to the support, and the catalyst body comprises phosphomolybdic acid and metallic silver coated on the phosphomolybdic acid.

[0031] In a third aspect, the present application provides an application of a catalyst, the catalyst being prepared by the catalyst preparation method described in the first aspect, and the application comprising using the catalyst in an anodic oxidation reaction of an organic substance.

[0032] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0033] In the method provided by the embodiment of the present application, by constructing a PMoA@C-N-Ag + complex structure and then in-situ reduction transformation, a (MoO X ) / Ag heterogeneous nanocatalyst supported on a support is formed. Utilize the catalytic intrinsic activity of phosphomolybdic acid, and use metallic Ag with good conductivity to coat PMoA, slow down electrode dissolution and ensure the conductivity of the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application and used together with the specification to explain the principles of the present application.

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0036] Figure 1 is a flowchart of the method provided by the embodiment of the present application;

[0037] Figure 2 is a transmission electron microscope image of the catalyst provided by Embodiment 1 of the present application;

[0038] Figure 3 is a size analysis and EDS elemental scanning result diagram of the catalyst provided by Embodiment 1 of the present application;

[0039] Figure 4 is an X-ray diffraction diagram of the complex PMoA@C-N-Ag + and the catalyst provided by Embodiment 1 of the present application;

[0040] Figure 5 is an infrared analysis spectrum diagram of the complex PMoA@C-N-Ag + and the catalyst provided by Embodiment 1 of the present application;

[0041] Figure 6 CV curve of the electrocatalytic oxidation of the catalyst provided in Example 1 of this application in 1M KOH;

[0042] Figure 7 CV curve of the electrocatalytic oxidation of the catalyst provided in Example 1 of this application in a mixed solution of 1M KOH + 1M glycerol;

[0043] Figure 8 CV curve of the electrocatalytic oxidation of the catalysts provided in Example 1 and Comparative Example 1 of this application in 1M KOH;

[0044] Figure 9 CV curve of the electrocatalytic oxidation of the catalysts provided in Example 1 and Comparative Example 1 of this application in 1M glycerol. Detailed implementation manners

[0045] To make the objectives, technical solutions and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of this application without creative efforts shall fall within the protection scope of this application.

[0046] Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments and equipment used in this application can be obtained through market purchase or can be prepared by existing methods.

[0047] Composite materials benefit from the regulation of the outer electron structure of active metal atoms and generally have more excellent catalytic performance compared with single-metal materials. In such catalysts, the regulating effect usually comes from the doped second metal. The doped metal has electronic and geometric effects on the active metal atom sites, thereby improving its catalytic activity. In addition to traditional second-metal doping, new dopants such as organic polymers, organometallic complexes and polyoxometalates have also attracted increasing attention. For example, Avnir et al. doped an organic dye (Congo red) in silver (Ag) to achieve high catalytic activity for methanol oxidation; by wrapping rhodium(I) complexes with Ag, high catalytic activity for styrene hydrogenation was achieved. In addition, the heterogeneous acid catalyst with H3PMo 12 O 40 wrapped in the metal silver matrix shows stronger catalytic performance for the alkylation reaction of aromatic hydrocarbons. Among these catalysts, polyoxometalates (POMs) can be used alone as acidic catalysts or as dopants to regulate the catalytic ability of active metals.

[0048] Phosphomolybdic acid (H3PMo 12 O 40 , H3PO4·12MoO3, Phosphomolybdic acid, abbreviated as PMoA) is a typical heteropolyacid with a Keggin structure. One P atom serves as the center, surrounded by 12 octahedral MoO6 structural units. PMoA has 36 oxygen atoms exposed on the surface and has fast multi-electron reversible redox characteristics under relatively mild conditions. It is an important and efficient oxidation catalyst commonly used in thermal catalytic reactions and is widely used in organic synthesis, organic matter oxidation, and non-carbon fuel cells. At the same time, phosphomolybdic acid PMoA can be used as a doping component in metal catalysts, which can affect the electron distribution of active metals and can also participate in intermediate reactions of oxygen activation and transfer, thereby changing the catalytic performance of metal catalysts. However, phosphomolybdic acid PMoA is extremely soluble in water and has poor conductivity, so it is difficult to apply in electrolytic water catalysis. The inventors found that phosphomolybdic acid PMoA can be anchored by metal atoms. These anchored metal atoms can serve as seeds for further deposition of metal atoms, thereby obtaining a core@shell heterogeneous composite structure with phosphomolybdic acid PMoA molecules in the core and metal in the shell.

[0049] The process of electrochemical water splitting to produce hydrogen includes a cathodic hydrogen evolution reaction (HER) and an anodic oxygen evolution reaction (OER). Since overcoming the energy barrier of the anodic oxygen evolution reaction (OER) requires a relatively high overpotential, matching an anodic oxidation reaction that is easier to occur for the cathodic hydrogen evolution reaction (HER) than the anodic oxygen evolution reaction (OER), such as the oxidation of small molecules like methanol, ethanol, and glycerol, is an important means to promote the efficiency of electrolytic water hydrogen production. The catalytic potential of composites of molybdenum oxide MoO x and metals in the electrocatalytic oxidation of organic small molecules has been somewhat confirmed. For example, Yu et al. reported a simple method for capturing Pt nanoparticles at the oxygen vacancies of molybdenum oxide (MoO x ) nanosheets, and designed and synthesized a high-performance MoO x / Pt composite electrocatalyst for glycerol oxidation reaction (GOR) and hydrogen evolution reaction (HER).

[0050] Therefore, the inventors intend to propose the construction of a phosphomolybdic acid-silver heterogeneous composite nanomaterial as a catalyst, utilizing the intrinsic catalytic activity of phosphomolybdic acid, coating phosphomolybdic acid PMoA with metal Ag with good conductivity to slow down electrode dissolution and ensure the conductivity of the electrode, and exploring the catalytic application of this composite material in the electrocatalytic oxidation of methanol, ethanol, glycerol, etc.

[0051] As Figure 1 shown, the embodiments of the present application provide a preparation method of a catalyst, and the method includes:

[0052] S1. Dissolve 1,2,4-triazole, a silver source, and phosphomolybdic acid in a first solvent, and then perform complexation to obtain an emulsion containing a PMoA@C-N-Ag + complexation structure;

[0053] The silver source refers to a substance that can provide anions, such as silver salts, etc.

[0054] In some embodiments, the silver source includes silver acetate. The first solvent includes ethylene glycol.

[0055] In some embodiments, the molar ratio of 1,2,4-triazole, the silver source, and phosphomolybdic acid is (1 - 3):(0.5 - 1.5):(0.1 - 0.3). Further, the molar ratio of 1,2,4-triazole, the silver source, and phosphomolybdic acid is (1.5 - 2.5):(0.8 - 1.2):(0.15 - 0.25). Exemplarily, the molar ratio of 1,2,4-triazole, the silver source, and phosphomolybdic acid can be 2:1:0.2, 1:0.5:0.1, 2:0.5:0.1, 3:0.5:0.1, 1:1:0.1, 2:1:0.1, 3:1:0.1, 1:1.5:0.1, 2:1.5:0.1, 3:1.5:0.1, 1:0.5:0.2, or 2:0.5:0.3, etc., and it can also be any value within the range of (1 - 3):(0.5 - 1.5):(0.1 - 0.3).

[0056] In some embodiments, the complexation environment is normal temperature and pressure, and the complexation time is 40 - 56 hours. Further, the complexation time is 44 - 52 hours. Exemplarily, the complexation time can be 40 hours, 41 hours, 42 hours, 43 hours, 44 hours, 45 hours, 46 hours, 47 hours, 48 hours, 49 hours, 50 hours, 51 hours, 52 hours, 53 hours, 54 hours, 55 hours, or 56 hours, etc., and it can also be any value within the range of 40 - 56 hours.

[0057] Specifically, in this embodiment, a quantitatively analyzed pure AR purity of 1,2,4-triazole, silver acetate CH3COOAg, and phosphomolybdic acid PMA are dissolved in an ethylene glycol solvent, stirred for 30 minutes to completely dissolve, and then continuously stirred for 48 hours in a normal temperature and pressure environment to obtain a light green emulsion containing a PMoA@C-N-Ag + complexation structure.

[0058] S2. Dissolve the carrier in a second solvent to obtain a carrier solution;

[0059] In some embodiments, the mass concentration of the carrier in the carrier solution is 0.003 - 0.005 g / mL. Exemplarily, the mass concentration of the carrier in the carrier solution can be 0.003 g / mL, 0.004 g / mL, 0.005 g / mL, etc., or it can also be any value within the range of 0.003 - 0.005 g / mL.

[0060] In some embodiments, the carrier includes carbon black. The second solvent includes ethylene glycol. Further, the carbon black includes vulcan XC - 72.

[0061] Specifically, in this embodiment, the amount of the carbon black carrier is calculated based on the loading amount of all metals being 25 wt%. Cabot vulcan XC - 72 is selected as the carbon black carrier, and ethylene glycol is selected as the solvent. A quantitative amount of carbon black and solvent are weighed into a beaker and ultrasonically dissolved in an ultrasonic cleaner for 30 minutes to obtain a carrier solution.

[0062] S3. Mix the carrier solution and the emulsion containing the PMoA@C - N - Ag + complex structure, and then perform in - situ reduction treatment to obtain a catalyst.

[0063] In some embodiments, the mass of the carrier is 20% - 30% of the mass of all metals in the PMoA@C - N - Ag + complex structure. Further, the mass of the carrier is 23% - 27% of the mass of all metals in the PMoA@C - N - Ag + complex structure. Exemplarily, the mass of the carrier can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30% of the mass of all metals in the PMoA@C - N - Ag + complex structure, etc., or it can also be any value within the range of 20% - 30%.

[0064] In some embodiments, the temperature of the in - situ reduction treatment is 130 - 230 °C; the time of the in - situ reduction treatment is 1 - 3 hours. Further, the temperature of the in - situ reduction treatment is 160 - 200 °C; the time of the in - situ reduction treatment is 1.5 - 2.5 hours. Exemplarily, the temperature of the in - situ reduction treatment can be 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, or 230 °C, etc., or it can also be any value within the range of 130 - 230 °C. The time of the in - situ reduction treatment can be 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, or 3 hours, etc., or it can also be any value within the range of 1 - 3 hours.

[0065] Specifically, in this embodiment, carbon black solution is added to PMoA@C-N-Ag + emulsion to obtain a mixed solution. The mixed solution is placed in a three-necked flask, heated to 180 °C under nitrogen protection, and maintained for 2 hours, and then naturally cooled to room temperature to obtain a colloidal solution containing the catalyst.

[0066] In some embodiments, the method further includes: cleaning the catalyst.

[0067] Specifically, in this embodiment, the colloidal solution obtained above is centrifuged at 8000 revolutions per minute to obtain a precipitate. The precipitate is added with 50 mL of ethanol and shaken to wash the organic matter in the precipitate, and then centrifuged at 8000 revolutions per minute to obtain a precipitate. The ethanol washing step is repeated 3 times, and the obtained precipitate is placed in a vacuum oven at 60 °C and dried overnight to obtain a carbon black-supported (MoO X ) / Ag composite nanomaterial that can be directly used as a catalyst.

[0068] This method constructs a PMoA@C-N-Ag + complex structure, and then in-situ reduces and transforms it to form a (MoO X ) / Ag heterogeneous nanocatalyst supported on the carrier. Utilize the catalytic intrinsic activity of phosphomolybdic acid, and use metal Ag with good conductivity to coat PMoA to slow down the electrode dissolution and ensure the conductivity of the electrode.

[0069] Based on a general inventive concept, an embodiment of the present application further provides a catalyst, and the catalyst is prepared by using the preparation method of the catalyst provided above.

[0070] This catalyst is prepared based on the above method. The specific steps of this method can refer to the above embodiments. Since this catalyst adopts some or all of the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated here one by one.

[0071] In some embodiments, the particle size of the catalyst is 11-16 nm. Exemplarily, the particle size of the catalyst can be 11 nm, 12 nm, 13 nm, 14 nm, 15 nm or 16 nm, etc., and it can also be any value within the range of 11-16 nm.

[0072] In some embodiments, the catalyst includes a carrier and a catalyst body attached to the carrier, and the catalyst body includes phosphomolybdic acid and metallic silver coated on the phosphomolybdic acid.

[0073] Based on a general inventive concept, an embodiment of the present application further provides an application of a catalyst, where the catalyst is prepared by using the catalyst preparation method provided above, and the application includes using the catalyst in the anodic oxidation reaction of organic substances.

[0074] This application is implemented based on the above method. For the specific steps of the method, reference can be made to the above embodiments. Since this application adopts some or all of the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated one by one here.

[0075] Specifically, in this embodiment, the composite material is applied to the anodic oxidation reaction of small organic molecules. The reaction is carried out in an electrochemical workstation, using a standard three-electrode system, with Hg / HgO as the reference electrode and a platinum sheet as the counter electrode. The test is carried out in a glass cell, which contains a mixed solution of 200 mL of 1.0 M KOH and 1 M glycerol as the electrolyte. The RHE potential is calculated by the formula E(RHE) = E(Hg / HgO) + 0.0591×pH + 0.097 V. Method for fabricating the catalytic electrode: Dissolve 5 mg of the catalyst in 920 μL of ethanol. After ultrasonic treatment for 30 minutes, then add 80 μL of Nafion. Use a pipette to pick 20 μL of the suspension and vertically drop it onto a disk electrode with an area of 0.196 cm 2 Then let it air-dry naturally in the air. The HER polarization curve is obtained by linear sweep voltammograms (LSVs), with a scan rate of 5 mV s -1 , and measured at a rate of 1600 rpm between voltages of 0.7 to 1.9 V (vs. RHE). Before each measurement, purge the electrolyte with N2 for 20 minutes to blow away the internal oxygen.

[0076] In the electrocatalytic glycerol oxidation reaction, the performance of this composite material is significantly improved compared with that of a single metal, which confirms the superiority of the composite structure and the feasibility of the synthesis strategy, achieving the purpose of matching an anodic oxidation reaction that is easier to occur than OER for HER in electrochemical water splitting for hydrogen production.

[0077] The following further elaborates the present application in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. For the experimental methods without specific conditions noted in the following embodiments, they are usually determined according to national standards. If there is no corresponding national standard, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0078] Example 1

[0079] A method for preparing a catalyst, the method includes:

[0080] 1. Take 2 mmol of 1,2,4-triazole, 1 mmol of silver acetate CH3COOAg, and 0.2 mmol of phosphomolybdic acid PMA, dissolve them in 30 mL of ethylene glycol, stir for 30 minutes until completely dissolved, and continue to stir continuously for 48 hours under normal temperature and pressure conditions to obtain a light green emulsion containing the PMoA@C-N-Ag + complex.

[0081] 2. Reserve one-third of the emulsion. Take 0.13 g of XC-72 carbon support (calculated based on a metal loading of 25 wt%) and dissolve it in 30 mL of ethylene glycol, and ultrasonically treat it at room temperature for 20 minutes in an ultrasonic cleaner. Mix the two mixed solutions and pour them into a 250 mL three-necked flask. Under nitrogen protection, heat up to 180 °C and maintain for 2 hours, and then naturally cool to room temperature.

[0082] 3. Centrifuge the obtained colloidal solution at 8000 revolutions per minute to obtain a precipitate. Add 50 mL of ethanol to the precipitate and shake it to wash the organic matter in the precipitate, and then centrifuge at 8000 revolutions per minute to obtain a precipitate. Repeat the ethanol washing step 3 times. Place the obtained precipitate in a 60 °C vacuum oven and dry it overnight to obtain a carbon black support-supported (MoO X ) / Ag composite nanomaterial.

[0083] 4. Take 5 mg of the synthesized material to prepare a catalytic electrode. The method for fabricating the catalytic electrode: Dissolve 5 mg of the catalyst in 920 μL of ethanol, after ultrasonication for 30 minutes, add 80 μL of Nafion, and use a pipette to pick 20 μL of the suspension and vertically drop it onto a 0.196 cm 2 disk electrode, and then let it air dry naturally in the air to obtain a catalytic electrode, and test the polarization curve of the catalytic anodic oxidation reaction. The polarization curve is obtained by linear sweep voltammograms (LSVs), with a scanning rate of 5 mV s -1 , and measure it at a rate of 1600 rpm between voltages of 0.7 to 1.9 V (vs. RHE). Before each measurement, purge the electrolyte with N2 for 20 minutes to blow away the internal oxygen. Compare the voltage and current of the oxidation reaction to analyze the activity and stability of the material in catalyzing the anodic oxidation of organic small molecules and water molecules.

[0084] Comparative Example 1

[0085] A method for preparing a catalyst, the method comprising:

[0086] 1. Dissolve 2 mmol of 1,2,4-triazole and 1 mmol of silver acetate CH3COOAg in 30 mL of ethylene glycol, stir for 30 minutes until completely dissolved. Take 0.324 g of XC-72 carbon support (calculated based on a metal loading of 25 wt%) and dissolve it in 30 mL of ethylene glycol, and ultrasonically treat it at room temperature for 20 minutes in an ultrasonic cleaner. Mix the two mixed solutions and pour them into a 250 mL three-necked flask. Under nitrogen protection, heat up to 180 °C and maintain for 2 hours, then naturally cool to room temperature.

[0087] 2. Centrifuge the obtained colloidal solution at 8000 revolutions per minute to obtain a precipitate. Add 50 mL of ethanol to the precipitate and shake it to wash the organic matter in the precipitate, then centrifuge at 8000 revolutions per minute to obtain a precipitate. Repeat the ethanol washing step 3 times. Place the obtained precipitate in a vacuum oven at 60 °C and dry it overnight to obtain a single-metal Ag nanomaterial supported on a carbon black support.

[0088] 3. Take 5 mg of the synthesized material to prepare a catalytic electrode. The method for fabricating the catalytic electrode: Dissolve 5 mg of the catalyst in 920 μL of ethanol, after ultrasonication for 30 minutes, then add 80 μL of Nafion. Use a pipette to pick 20 μL of the suspension and vertically drop it onto a disk electrode with a diameter of 0.196 cm 2 . Then let it air-dry naturally in the air to obtain a catalytic electrode, and test the polarization curve of the catalytic anodic oxidation reaction. The polarization curve is obtained by linear sweep voltammograms (LSVs), with a scan rate of 5 mV s -1 . Measure at a rate of 1600 rpm between voltages of 0.7 to 1.9 V (vs. RHE). Before each measurement, purge the electrolyte with N2 for 20 minutes to blow away the internal oxygen. Compare the voltage and current of the oxidation reaction to analyze the activity and stability of the material in catalyzing the anodic oxidation of organic small molecules and water molecules.

[0089] Perform transmission electron microscopy scanning, size analysis, and EDS elemental scanning analysis on the catalyst provided in Example 1. The results are as shown in Figure 2 and Figure 3 . Figure 2 is the transmission electron micrograph of the catalyst provided in Example 1 of this application; Figure 3 is the size analysis and EDS elemental scanning result diagram of the catalyst provided in Example 1 of this application; It can be seen from the figure that through the TEM transmission electron microscope image, it can be found that the carbon black support-supported (MoO X ) / Ag composite nanomaterial synthesized by this method, where (MoO X) / Ag are spherical particles with uniform size and morphology, and the diameter is about 13 nanometers. The EDS elemental analysis results prove that several elements such as Ag, P, Mo, and O overlap and are evenly distributed in the nanoparticles, indicating the successful synthesis of the composite nanomaterial.

[0090] Perform XRD tests and infrared analyses on the complex PMoA@C-N-Ag + provided in Example 1 and the catalyst respectively, and the results are as Figure 4 and Figure 5 shown. Figure 4 This is the X-ray diffraction pattern of the complex PMoA@C-N-Ag + and the catalyst provided in Example 1 of this application; Figure 5 This is the infrared analysis spectrum of the complex PMoA@C-N-Ag + and the catalyst provided in Example 1 of this application; It can be seen from the figure that through X-ray diffraction (XRD) characterization, the (MoO X ) / Ag composite nanomaterial supported by the carbon black carrier shows two sets of diffraction peaks, which are the diffraction peaks of metallic Ag and phosphomolybdic acid PMoA respectively, indicating that this material is a heterogeneous material formed by the combination of two materials. And the lattice diffraction of the complex PMoA@C-N-Ag + shows a large peak, which is due to the fact that metal salt ions are not reduced and the crystallinity of the complex is poor. Infrared characterization can directly prove the bonding retention of phosphomolybdic acid in the composite material before and after reduction. The (MoO X ) / Ag composite nanomaterial still has two kinds of bonds, P-O and Mo-O-Mo, indicating that the MoOx part in phosphomolybdic acid is retained. Therefore, it is reasonable to define the material as (MoO X ) / Ag.

[0091] Test the CV curves of the catalysts provided in Example 1 and Comparative Example 1 in a mixed solution of 1M KOH and 1.0M KOH + 1M glycerol between voltages of 0.7 to 1.9V (vs. RHE). As Figures 6 to 9 shown, Figure 6 This is the CV curve of the electrocatalytic oxidation of the catalyst provided in Example 1 of this application in 1M KOH; In 1M KOH alkaline solution, the composite material (MoO X ) / Ag shows two pairs of redox peaks, and there is almost no performance in catalyzing the electrolysis of water to evolve oxygen (OER), indicating that this material is not suitable as an OER catalyst. Figure 7 This is the CV curve of the electrocatalytic oxidation of the catalyst provided in Example 1 of this application in a mixed solution of 1M KOH + 1M glycerol; When 1M glycerol (GLY) is added to the electrolyte, the polarization curve changes significantly, and the current at the same voltage increases significantly, indicating that the composite material (MoO X) / Ag has a high ability to catalyze the oxidation of glycerol. Figure 8 This is the CV curve graph of the electrocatalytic oxidation of the catalysts provided in Example 1 and Comparative Example 1 of this application in 1M KOH; Figure 9 This is the CV curve graph of the electrocatalytic oxidation of the catalysts provided in Example 1 and Comparative Example 1 of this application in 1M glycerol. It can be seen from the figure that by comparing with the catalyst of Comparative Example 1, although the performance of the composite material in catalyzing OER has not been significantly improved, the catalytic ability for glycerol oxidation has been significantly enhanced.

[0092] The various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the description of the range has specifically disclosed all possible sub-ranges and the individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and the individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0093] In this application, unless otherwise stated, the orientation terms such as "upper" and "lower" specifically refer to the drawing direction in the drawings. Additionally, in the description of this application's specification, the terms "include", "comprise", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural. In this article, "at least one" means one or more, and "multiple" means two or more. "At least one kind", "at least one of the following items (pieces)" or similar expressions refer to any combination of these items, including any combination of single item (piece) or plural items (pieces). For example, "at least one of a, b, or c", or, "at least one of a, b, and c" can all represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0094] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a catalyst, characterized in that, The method includes: Dissolve 1,2,4-triazole, silver source and phosphomolybdic acid in the first solvent, and then carry out complexation to obtain an emulsion containing PMoA@C-N-Ag + with a complex structure; Dissolving the carrier in a second solvent to obtain a carrier solution; Mix the carrier solution with the emulsion containing the PMoA@C-N-Ag + complex structure, and then perform in-situ reduction treatment to obtain a catalyst.

2. The preparation method of the catalyst according to claim 1, characterized in that, The silver source includes silver acetate.

3. The preparation method of the catalyst according to claim 1, characterized in that, The first solvent includes ethylene glycol.

4. The preparation method of the catalyst according to claim 1, characterized in that, The molar ratio of the 1,2,4-triazole, the silver source and the phosphomolybdic acid is (1 - 3):(0.5 - 1.5):(0.1 - 0.3).

5. The preparation method of the catalyst according to claim 1, characterized in that, The molar ratio of the 1,2,4-triazole, the silver source and the phosphomolybdic acid is (1.5 - 2.5):(0.8 - 1.2):(0.15 - 0.25).

6. The preparation method of the catalyst according to claim 1, characterized in that, The complexing environment is normal temperature and pressure, and the complexing time is 40 - 56 hours.

7. The preparation method of the catalyst according to claim 6, characterized in that, The complexing time is 44 - 52 hours.

8. The preparation method of the catalyst according to claim 1, characterized in that, The mass of the carrier is 20% to 30% of the mass of all metals in the PMoA@C-N-Ag + complex structure.

9. The preparation method of the catalyst according to claim 8, characterized in that, The mass of the carrier is 23% to 27% of the mass of all metals in the PMoA@C-N-Ag + complex structure.

10. The preparation method of the catalyst according to claim 1, characterized in that, The mass concentration of the carrier in the carrier solution is 0.003 - 0.005 g / mL.

11. The preparation method of the catalyst according to claim 1, characterized in that, The carrier includes carbon black.

12. The preparation method of the catalyst according to claim 11, characterized in that, The carbon black includes vulcan XC-72.

13. The preparation method of the catalyst according to claim 1, wherein, The second solvent includes ethylene glycol.

14. The preparation method of the catalyst according to claim 1, wherein The temperature of the in-situ reduction treatment is 130 - 230 °C; and / or The time of the in-situ reduction treatment is 1 - 3 hours.

15. The preparation method of the catalyst according to claim 14, characterized in that, The temperature of the in-situ reduction treatment is 160 - 200 °C; and / or The time of the in-situ reduction treatment is 1.5 - 2.5 hours.

16. The preparation method of the catalyst according to claim 1, characterized in that, The method further includes: cleaning the catalyst.

17. A catalyst, characterized in that, The catalyst is prepared by using the catalyst preparation method described in any one of claims 1 to 16.

18. The catalyst according to claim 17, characterized in that, The particle size of the catalyst is 11 - 16 nm.

19. The catalyst according to claim 17, wherein The catalyst includes a carrier and a catalyst body attached to the carrier, and the catalyst body includes phosphomolybdic acid and metallic silver coated on the phosphomolybdic acid.

20. Application of a catalyst, characterized in that, The catalyst is prepared by using the catalyst preparation method described in any one of claims 1 to 16, and the application includes using the catalyst in the anodic oxidation reaction of organic substances.

Images