A SnO2GN composite support for PtMo alloy catalyst, its preparation method and application

Abstract

This invention relates to the field of electrochemical catalysis technology, specifically to a SnO2GN composite support-supported PtMo alloy catalyst, its preparation method, and its application. The specific technical solution is as follows: a method for preparing a SnO2GN composite support-supported PtMo alloy catalyst, using a SnO2GN composite support composed of SnO2 and graphene as the catalyst support, and PtMo alloy as the active component, by supporting the PtMo alloy on the SnO2GN composite support to obtain a PtMo / SnO2GN catalyst. This invention solves the problems of low catalytic efficiency and easy degradation during the reaction process of Pt-based catalysts in practical applications of ethanol electro-oxidation; the prepared catalyst has more active sites during ethanol electro-oxidation, resulting in enhanced catalytic effect, significantly improved catalyst resistance to poisoning, reduced influence of poisoning intermediates during the reaction process, extended catalyst lifespan, and improved catalyst cycle stability.

Description

Technical Field

[0001] This invention relates to the field of electrochemical catalysis technology, specifically to a SnO2GN composite support-supported PtMo alloy catalyst, its preparation method, and its application. Background Technology

[0002] Direct ethanol fuel cells (DEFCs) are clean energy devices that use ethanol as fuel and convert chemical energy into electrical energy through an electrochemical reaction. Due to ethanol's advantages such as high energy density, wide availability, ease of storage and transportation, and safe use, DEFCs have great potential in replacing traditional fossil fuels and reducing greenhouse gas emissions. However, the commercial application of DEFCs still faces many challenges, especially regarding the efficiency and stability of the ethanol electrooxidation catalyst. An ideal ethanol electrooxidation catalyst not only needs to efficiently and completely oxidize ethanol to CO2, but also must be resistant to poisoning to cope with the poisoning effects of intermediates (such as CO) generated during the reaction. The accumulation of these intermediates can significantly reduce catalyst activity, thus affecting the overall performance of the cell.

[0003] Currently, Pt-based catalysts are widely used in the research of ethanol electrooxidation catalysts. However, single Pt catalysts are easily poisoned by intermediate products such as CO during long-term use, leading to a rapid decline in catalytic performance. Therefore, researching and developing catalysts with high efficiency, stability, and strong resistance to poisoning is key to improving DEFC performance. To obtain high-efficiency and stable ethanol electrooxidation catalysts, researchers have developed composite catalysts by introducing a second metal or metal oxide as a Pt co-catalyst to form composite catalysts, thereby improving the resistance to poisoning and cycle stability of ethanol electrooxidation catalysts. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a SnO2GN composite support for a PtMo alloy catalyst, its preparation method, and its application, solving the problems of low catalytic efficiency of ethanol electro-oxidation and easy degradation during the reaction process faced by Pt-based catalysts in practical applications.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention discloses a method for preparing a PtMo alloy catalyst supported on a SnO2GN composite support. The SnO2GN composite support, composed of SnO2 and graphene, is used as the catalyst support, and the PtMo alloy is used as the active component. The PtMo alloy is supported on the SnO2GN composite support to obtain the PtMo / SnO2GN catalyst.

[0007] Preferably, the total mass fraction of PtMo alloy in the PtMo / SnO2GN catalyst is 3-10%, the atomic ratio of Pt to Mo in the PtMo alloy is 1:1 to 1:5, and the mass loading ratio of SnO2 is 5-20%.

[0008] Preferably, the SnO2GN composite carrier is prepared by using ammonia water as a precipitant and soluble tin source and graphene as raw materials via a sol-gel method; the concentration of the ammonia water is 0.4-0.6 mol / L, the concentration of the tin source is 0.1 mol / L; the tin source is tin tetrachloride, and the graphene is graphene that has been oxidized by nitric acid or sulfuric acid vapor and H2O2.

[0009] Preferably, the graphene oxidation process is as follows: concentrated nitric acid or concentrated sulfuric acid is heated to generate acid vapor, and the graphene is continuously heated in the concentrated acid vapor environment for acid treatment. After the treatment is stopped, the temperature of the graphene is maintained to dry the graphene treated with acid vapor. The graphene is washed until the pH value of the filtrate is 7. Then it is transferred to H2O2 solution for heating treatment, ultrasonicated for 1 to 3 hours, washed clean with deionized water, dried in a vacuum drying oven for 8 to 12 hours, and ground for 10 to 20 minutes to obtain oxidized graphene.

[0010] Preferably, the concentrated nitric acid or concentrated sulfuric acid is heated separately from the graphene. The heating temperature of the concentrated nitric acid or concentrated sulfuric acid is 130-150°C, and the graphene is continuously heated in the concentrated acid vapor environment at a temperature of 110-130°C for 7-9 hours. After the concentrated acid heating is stopped, the temperature of the graphene is maintained to dry the graphene treated with acid vapor at 110-130°C for 24 hours.

[0011] Preferably, the concentration of the H2O2 solution is 3-30%, the heat treatment temperature is 60°C, and the time is 10 min; after heat treatment, it is washed with deionized water at least 3 times.

[0012] Preferably, the process of supporting the PtMo alloy on the SnO2GN composite carrier is as follows: it is prepared by microwave reduction using ethylene glycol as a reducing agent and soluble platinum source and molybdenum source as raw materials; the platinum source is chloroplatinic acid and the molybdenum source is ammonium molybdate.

[0013] Preferably, a 0.1–0.2 mol / L ethylene glycol chloroplatinate solution and a 0.1–0.2 mol / L ethylene glycol ammonium molybdate solution are mixed and stirred for 30 min. Then, a SnO2GN composite support is added, and the mixture is sonicated and stirred for 30 min each to form a homogeneous solution. 3–5 wt.% NaOH / EG is added to adjust the pH to 9–10 to obtain a precursor solution. The precursor solution is heated to 160–180 °C in a microwave reactor at a power of 450–550 W and held for 90 s. After cooling, the pH is adjusted to 5–7 using a 3–5 wt.% dilute nitric acid aqueous solution and stirred for 30 min. The solution is washed until the filtrate is neutral, vacuum dried, and then treated with plasma in an Ar environment for 5–15 min to obtain the PtMo / SnO2GN catalyst.

[0014] Correspondingly, a SnO2GN composite support for a PtMo alloy catalyst is provided, wherein the total mass fraction of PtMo alloy in the PtMo / SnO2GN catalyst is 3-10%, the atomic ratio of Pt to Mo in the PtMo alloy is 1:1-1:5, and the mass loading ratio of SnO2 is 5-20%.

[0015] Correspondingly, an application of a SnO2GN composite support-supported PtMo alloy catalyst in the catalytic electro-oxidation reaction of ethanol in a direct ethanol fuel cell.

[0016] The present invention has the following beneficial effects:

[0017] 1. In the process of GN (graphene) oxidation treatment, the present invention first performs high-temperature oxidation with concentrated nitric acid or sulfuric acid, and then treats it with hydrogen peroxide. This can not only achieve the purification purpose of oxidizing and removing carbon debris in and on the surface of GN, but also introduce -NO, -NO2 and -OH groups on the surface of GN to coordinate with the SnO2 precursor colloid formed later, which is beneficial to the uniform distribution of SnO2 on the surface of GN.

[0018] 2. In the synthesis of the SnO2GN composite support in this invention, a sol-gel method is used to load a gel-like precipitate onto oxidized graphene and then perform rotary evaporation and vacuum calcination. The resulting SnO2 is uniformly distributed on GN. The SnO2GN composite support exhibits excellent hydrophilicity and conductivity, providing a good dispersion platform for PtMo alloy nanoparticles to be supported on the support. This results in a very uniform distribution of PtMo alloy nanoparticles on the SnO2GN composite support, thus leading to higher catalyst utilization efficiency and a higher current density obtained from ethanol oxidation.

[0019] 3. The PtMo / SnO2GN composite catalyst provided by this invention uses transition metal Mo as a co-catalyst for Pt. Mo can change the electronic structure of Pt in the alloy, reducing the adsorption energy of intermediate products such as CO. At the same time, the oxygen vacancies generated during the vacuum calcination of SnO2 precursor can adsorb oxygen-containing species, which can increase the oxidation rate of intermediate products such as CO. Mo also facilitates the breaking of C-C bonds during ethanol oxidation. Therefore, the PtMo alloy can effectively promote the complete oxidation of ethanol, generating more CO2 instead of intermediate products, thus improving catalytic efficiency and catalytic stability. Attached Figure Description

[0020] Figure 1 The XRD patterns of the Pt1Mo3 / SnO2GN and Pt / GN catalysts in Example 1 are shown.

[0021] Figure 2 This is a transmission electron microscope (TEM) image of the PtMo alloy catalyst supported on a SnO2GN composite support with a PtMo atomic ratio of 1:3 in Example 1.

[0022] Figure 3 This is a comparison of the chronocurrent stability of PtMo alloy catalysts supported on SnO2GN composite supports with different PtMo atomic ratios in Example 1. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Unless otherwise specified, the technical means used in the implementation examples are conventional means well known to those skilled in the art.

[0025] 1. The SnO2GN composite support-supported PtMo alloy catalyst disclosed in this invention uses a SnO2GN composite support composed of SnO2 and graphene as the catalyst support, and a PtMo alloy as the active component. Mo acts as a co-catalyst for Pt, forming an alloy with Pt. The PtMo alloy is supported on the SnO2GN composite support, thus obtaining the PtMo / SnO2GN catalyst. The total mass fraction of the PtMo alloy in the PtMo / SnO2GN catalyst is 3-10%, the atomic ratio of Pt to Mo in the PtMo alloy is 1:1 to 1:5, and the mass loading ratio of SnO2 is 5-20%.

[0026] The SnO2GN composite carrier is prepared by using ammonia water as a precipitant and soluble tin source and graphene as raw materials through a sol-gel method and calcination in a vacuum tube furnace. The tin source is tin tetrachloride and the graphene is graphene that has undergone oxidation treatment.

[0027] The PtMo alloy supported on the SnO2GN composite carrier is achieved by microwave reduction using ethylene glycol as a reducing agent and soluble platinum and molybdenum sources as raw materials. The platinum source is chloroplatinic acid and the molybdenum source is ammonium molybdate.

[0028] 2. The specific preparation steps of the SnO2GN composite support for PtMo alloy catalyst are as follows:

[0029] S1. Oxidation treatment of graphene: Concentrated nitric acid or concentrated sulfuric acid is heated to generate acid vapor. Graphene is continuously heated in the concentrated acid vapor environment for acid treatment. After the treatment is stopped, the temperature of the graphene is maintained to dry the graphene treated with acid vapor. Then, the graphene is washed with deionized water until the pH of the filtrate is 7. Then, it is transferred to H2O2 solution for heating treatment. After sonication for 1-3 hours, it is washed clean with deionized water. It is then dried in a vacuum drying oven for 8-12 hours and ground for 10-20 minutes to obtain oxidized graphene.

[0030] In this process, concentrated nitric acid or concentrated sulfuric acid and graphene are heated separately under controlled conditions. The heating temperature of the concentrated nitric acid or concentrated sulfuric acid is 130–150℃, while the graphene is continuously heated in a concentrated acid vapor environment at a temperature of 110–130℃ for 7–9 hours. After the concentrated acid heating is stopped, the graphene is dried by maintaining the temperature at 110–130℃ for 24 hours. Then, it is heated in an H2O2 solution with a concentration of 3–30% at a temperature of 60℃ for 10 minutes. After heat treatment, it is washed with deionized water at least three times.

[0031] Preparation of S2.SnO2GN composite support: 0.4-0.6 mol / L NH4OH solution was added dropwise to 0.1 mol / L SnCl4 aqueous solution and stirred continuously until no more sol was produced. The mixture was aged for 3-5 h, centrifuged and washed three times with water. The resulting gel-like substance was then added to the graphene suspension aqueous solution after oxidation treatment in S1 and stirred for 5-7 h. The mixture was then allowed to stand for 24 h. The mixed solution was rotary evaporated at 80 °C for 1-3 h. The rotary evaporated sample was then calcined in a vacuum tube furnace at 550 °C for 2-3 h to obtain the SnO2GN composite support.

[0032] S3. Preparation of precursor solution: Mix 0.1-0.2 mol / L ethylene glycol chloroplatinate solution and 0.1-0.2 mol / L ethylene glycol ammonium molybdate solution and stir for 30 min. Then add SnO2GN composite carrier, sonicate and stir for 30 min each to form a homogeneous solution, and add 3-5 wt.% NaOH / EG to adjust the pH value to 9-10.

[0033] In this process, ethylene glycol solutions of chloroplatinic acid and ammonium molybdate of equal concentration are mixed and stirred, wherein the atomic ratio of Pt to Mo is 1:1 to 1:5.

[0034] S4. Microwave reduction: Transfer the pH-adjusted precursor solution from S3 to a three-necked flask, heat it to 160-180℃ in a microwave reactor at 450-550W and hold for 90 seconds; after standing and cooling, adjust the pH to 5-7 with 3-5 wt.% dilute nitric acid aqueous solution and stir for 30 minutes.

[0035] S5. Drying-Plasma Treatment: Filter and wash the solution stirred in S4 with deionized water until the filtrate is neutral. Dry the collected powder in a vacuum oven at 80°C for 8-12 hours, and then treat it with plasma in an Ar environment for 5-15 minutes with a discharge power of 200W to obtain the PtMo / SnO2GN catalyst, i.e., the SnO2GN composite support-supported PtMo alloy catalyst.

[0036] 3. Application of the SnO2GN composite support-supported PtMo alloy catalyst prepared in this invention in the electrocatalytic oxidation of ethanol in a direct ethanol fuel cell.

[0037] Example 1

[0038] This embodiment provides a method for preparing PtMo alloy catalysts supported on a SnO2GN composite support with a SnO2 content of 20% at five different PtMo ratios (Pt:Mo atomic ratios of 1:1, 1:2, 1:3, 1:4, and 1:5, respectively). The steps are as follows:

[0039] (1) Oxidation treatment of graphene: 200 mL of concentrated nitric acid was placed in a three-necked flask, and 2 g of graphene was placed in a quartz tube with a sand core wrapped in an electric heating mantle. The quartz tube was inserted into the right neck of the three-necked flask. The three-necked flask was heated to 140 °C in an oil bath to generate acid vapor from the concentrated nitric acid. The electric heating mantle was kept at 120 °C to maintain the temperature of the graphene in the concentrated nitric acid vapor environment for 8 hours. After the concentrated nitric acid heating was stopped, the temperature of the electric heating mantle was maintained to dry the graphene treated with acid vapor at 120 °C for 24 hours.

[0040] The graphene was then washed with deionized water until the pH of the filtrate was 7. The washed graphene was then transferred to a 30% H2O2 solution and heat-treated at 60°C for 10 min. After sonication for 2 h, it was washed three times with deionized water, dried in a vacuum drying oven for 12 h, and ground for 20 min to obtain oxidized graphene.

[0041] (2) Preparation of SnO2GN composite carrier: 0.5 mol / L NH4OH solution was added dropwise to 0.1 mol / L SnCl4 aqueous solution and stirred continuously until no more precipitate was produced. After aging for 4 h, the mixture was centrifuged and washed with water three times. Then the resulting gel-like substance was added to the above (step (1)) acid-treated graphene (100 mg) suspension aqueous solution and stirred for 6 h. After standing for 24 h, the mixed solution was rotary evaporated at 80 °C for 1 h. The rotary evaporated sample was placed in a vacuum tube furnace and calcined at 550 °C for 2 h to obtain SnO2GN composite carrier.

[0042] (3) Preparation of precursor solutions: 0.1 mol / L ethylene glycol chloroplatinate solution and 0.1 mol / L ethylene glycol ammonium molybdate solution were mixed and stirred in five beakers at PtMo atomic ratios of 1:1, 1:2, 1:3, 1:4 and 1:5 respectively for 30 min. Then SnO2GN composite carrier was added, and the mixture was sonicated and stirred for 30 min each to form a homogeneous solution. 5 wt.% NaOH / EG was added to adjust the pH to 10, thus obtaining five precursor solutions.

[0043] (4) Microwave reduction: The five pH-adjusted precursor solutions were transferred to five three-necked flasks and heated to 170°C in a microwave reactor at 450W for 90 seconds. After cooling, the pH was adjusted to 5 using a 5 wt.% dilute nitric acid solution and stirred for 30 minutes.

[0044] (5) Drying-plasma treatment: Filter and wash the five portions of solution stirred in step (4) above with deionized water until the filtrate is neutral. Dry the collected wet sample at 80°C for 12 hours in a vacuum oven and then treat it with plasma (200W) in an Ar environment for 10 minutes to obtain five PtMo / SnO2GN catalysts with different PtMo ratios, namely PtMo alloy catalysts supported on SnO2GN composite support, which are respectively named Pt1Mo1 / SnO2GN, Pt1Mo2 / SnO2GN, Pt1Mo3 / SnO2GN, Pt1Mo4 / SnO2GN, and Pt1Mo1 / SnO2GN.

[0045] PtMo / SnO2GN and Pt / GN were detected using X-ray powder diffraction. The presence and shift of diffraction peaks at different locations can be used to determine whether the SnO2GN composite carrier and PtMo alloy have formed.

[0046] The X-ray diffraction patterns of PtMo / SnO2GN and Pt / GN with a PtMo atomic ratio of 1:3 in Example 1 are shown below. Figure 1 As shown. By Figure 1 It can be seen that both catalysts exhibit characteristic diffraction peaks of the face-centered cubic structure of Pt, with significant diffraction peaks appearing at positions of approximately 33.8° and 51.7° at 2θ. These peaks are attributed to SnO2 diffraction peaks, while the diffraction peak appearing at 26° can be attributed to graphitic carbon diffraction peaks, confirming the successful formation of the SnO2GN composite support. When Mo is introduced, the characteristic diffraction peaks of Pt undergo a negative shift, indicating the formation of a PtMo alloy.

[0047] The transmission electron microscopy (TEM) image of the PtMo alloy catalyst supported on the SnO2GN composite support with a PtMo atomic ratio of 1:3 in Example 1 is shown below. Figure 2 As shown. By Figure 2 It is known that in the SnO2GN composite support for PtMo alloy catalyst of the present invention, graphene has a thin layer structure and is stacked to form a wrinkled appearance. There are no obvious agglomerates and many fine nanoparticles are uniformly distributed, indicating that PtMo alloy is uniformly reduced and loaded on SnO2GN composite support, has good dispersibility, and provides more active sites.

[0048] Example 2

[0049] The electrochemical performance of the five SnO2GN composite-supported PtMo alloy catalysts prepared in Example 1 as anode ethanol electrooxidation catalysts for direct ethanol fuel cells was evaluated and tested.

[0050] The performance evaluation of five SnO2GN composite supports for PtMo alloy catalysts was carried out by preparing them into electrodes and forming a three-electrode test system for quantitative analysis on an electrochemical workstation (CHI660E, Shanghai Chenhua Instrument Co., Ltd.).

[0051] 1. Preparation of working electrode

[0052] Take 1 mg of the prepared SnO2GN composite support to support the PtMo alloy catalyst, mix it with 51 μL of Nafion solution (nafion:EG = 2:8) and 102 μL of deionized water to prepare an electrode slurry, sonicate for 30 min, then take 15 μL of the sonicated slurry and coat it evenly on the working electrode, then place the working electrode in an oven to dry, and use the dried electrode as the working electrode.

[0053] 2. Cyclic Voltmeter-Ammeter Test

[0054] A three-electrode testing system was formed by purging the dried working electrode, reference electrode, and counter electrode with nitrogen gas for 20 min to achieve saturation before testing. Cyclic voltammetry was performed in an electrolyte solution with a concentration of 0.5 mol / L H2SO4, and the electrochemical active surface area (ECSA) of the catalyst was calculated. Cyclic voltammetry was also performed in an electrolyte solution of 0.5 mol / L H2SO4 + 0.5 mol / L C2H5OH, and the peak current density (IL) was used during the positive scan. f ) and the peak current density of the negative sweep (I b The activity of the catalyst in the electro-oxidation of ethanol was evaluated using the ratio (I) f / I b This is used to evaluate the accumulation of residual intermediates during the oxidation process.

[0055] In this embodiment, the CHI660E electrochemical workstation of Shanghai Chenhua was used for testing. The reference electrode was a saturated calomel electrode, the counter electrode was a platinum sheet electrode, the potential range was -0.2 to 1V, and the test temperature was 25℃.

[0056] 3. Timing Current Test

[0057] Chronoamperometry is a controlled potential analysis method that measures the current changing over time at a given potential. After the cyclic voltammetry test was completed, the catalyst was subjected to a 3600s chronoamperometry test in an electrolyte solution of 0.5 mol / L H2SO4 + 0.5 mol / L C2H5OH, with a certain voltage applied, to evaluate the stability of the catalyst for the electro-oxidation reaction of ethanol. The test voltage was 0.5V.

[0058] 4. CO leaching test

[0059] CO is considered the main poison in the ethanol oxidation process. To assess the catalyst's resistance to CO poisoning, a CO dissolution test is performed. This test involves two consecutive cyclic voltammetric scans to complete the oxidation of CO on the catalyst.

[0060] The specific implementation steps are as follows: Nitrogen gas is passed into an electrolyte solution with a concentration of 0.5 mol / L H2SO4 for 20 minutes to remove dissolved oxygen; then CO gas is passed into the solution for 15 minutes to saturate the solution with CO; finally, nitrogen gas is passed into the solution for 20 minutes to remove the remaining CO gas, thereby forming a monolayer of CO on the electrode surface. After the gas passage is completed, a CO dissolution test is performed with a potential range of -0.2 to 1 V and a test temperature of 25℃.

[0061] The electrochemical performance data of the five SnO2GN composite supports supporting PtMo alloy catalysts (Pt:Mo atomic ratios of 1:1, 1:2, 1:3, 1:4, and 1:5, respectively) provided in Example 1 in the electro-oxidation reaction of ethanol are shown in Table 1. The 0.5V chronocurrent stability data are as follows: Figure 3 As shown.

[0062] Table 1 Electrochemical performance of PtMo alloy catalysts supported on SnO2GN composite support

[0063] catalyst <![CDATA[ECSA(m 2 ·g -1 Pt )]]> <![CDATA[I f (mA·mg -1 Pt )]]> <![CDATA[I b (mA·mg -1 Pt )]]> <![CDATA[I f / I b ]]> CO oxidation peak potential (V) <![CDATA[Pt1Mo1 / SnO2GN]]> 54.7 1388.9 1147.9 1.21 0.70 <![CDATA[Pt1Mo2 / SnO2GN]]> 80.2 1643.6 1192.1 1.38 0.66 <![CDATA[Pt1Mo3 / SnO2GN]]> 129.3 1898.7 1293.8 1.47 0.62 <![CDATA[Pt1Mo4 / SnO2GN]]> 105.8 1593.2 1271.2 1.25 0.69 <![CDATA[Pt1Mo5 / SnO2GN]]> 94.4 1439.4 1189.5 1.21 0.71

[0064] As shown in Table 1, with the increase of Mo atomic weight, the electrochemical active surface area and the peak current density of the SnO2GN composite support for PtMo alloy catalyst first increased and then decreased. When the PtMo atomic ratio was 1:3, the electrochemical active surface area and the peak current density of the catalyst reached their maximum, with a maximum active surface area of ​​129.3 m². 2 ·g -1 Pt The highest positive scan peak current density reached 1898.7 mA·mg. -1 Pt At this point, the ratio of the peak current density of the catalyst during the positive and negative sweeps in the ethanol electro-oxidation process reaches (I f / I b The highest value indicates that this catalyst leaves the fewest intermediate products during the electro-oxidation of ethanol. When the PtMo atomic ratio is 1:3, its peak potential for CO electro-oxidation is the lowest among the five catalysts at 0.62V, indicating that this catalyst has the best tolerance to CO and CO-like species during the electro-oxidation of ethanol.

[0065] like Figure 3 It can be seen that the current density of PtMo catalysts with all atomic ratios decayed rapidly before 600s of chronoamperometry testing. This is because Pt was poisoned by intermediates such as CO. After 1200s, the change in current density gradually leveled off and tended to stabilize. The PtMo alloy catalyst supported on the SnO2GN composite support with a PtMo atomic ratio of 1:3 had the highest current density, indicating that the catalytic stability of the PtMo atomic ratio of 1:3 was the best.

[0066] Comparative Example 1

[0067] This comparative example provides the electrochemical performance of Pt1Mo3 / SnO2GN and Pt / GN prepared in Example 1 as ethanol electrooxidation catalysts in direct ethanol fuel cells. The test methods and calculation standards in this comparative example are the same as those in Example 2, and will not be repeated here. The electrochemical performance data of Pt1Mo3 / SnO2GN and Pt / GN in the ethanol electrooxidation reaction are shown in Table 2.

[0068] Table 2 Electrochemical performance of Pt1Mo3 / SnO2GN and Pt / GN in the electrooxidation reaction of ethanol.

[0069]

[0070] As shown in Table 2, compared with the Pt / GN catalyst, the Pt1Mo3 / SnO2GN catalyst prepared in this invention exhibits superior catalytic performance in ethanol electrooxidation. The electrochemical active surface area, positive scan peak current density, and tolerance to ethanol oxidation intermediates are all significantly improved.

[0071] Comparative Example 2

[0072] This comparative example provides a comparison of the catalytic performance and CO poisoning resistance of the Pt1Mo3 / SnO2GN catalyst prepared in Example 1 with those obtained by treating graphene with only nitric acid vapor, Pt1Mo3 / SnO2GN(N) obtained by drying SnO2 precursor in a blower and calcining in air, and Pt1Mo3 / SnO2GN(P) obtained without plasma treatment, when used as ethanol electrooxidation catalysts.

[0073] In addition, the test methods and calculation standards in this comparative example are the same as those in Example 2, and will not be repeated here. The electrochemical performance and CO poisoning resistance of the four Pt1Mo3 alloy composite materials, namely Pt1Mo3 / SnO2GN, Pt1Mo3 / SnO2GN(N), Pt1Mo3 / SnO2GN(A), and Pt1Mo3 / SnO2GN(P), in the catalytic electro-oxidation of ethanol are shown in Table 3.

[0074] Table 3. Performance comparison of Pt1Mo3 / SnO2GN prepared in Example 1 with related catalysts.

[0075]

[0076] As shown in Table 3, compared with SnO2GN-supported PtMo alloys such as Pt1Mo3 / SnO2GN(N), Pt1Mo3 / SnO2GN(A) and Pt1Mo3 / SnO2GN(P), the Pt1Mo3 / SnO2GN composite material prepared in this invention exhibits superior ethanol electro-oxidation performance and CO poisoning resistance, with significant improvements in ethanol oxidation initiation potential, peak potential, and CO poisoning resistance.

[0077] Through the above experiments and comparative analysis, it is known that when the SnO2 content is 20%, the molar ratio of Pt to Mo is 1:3, the PtMo alloy content is 10%, and the calcination temperature is 550℃, the prepared PtMo / SnO2GN composite material exhibits higher catalytic activity, lower charge transfer resistance, and higher current density for ethanol oxidation. Furthermore, compared with composite materials such as Pt1Mo3 / SnO2GN(N) obtained by treating graphene with only nitric acid vapor, Pt1Mo3 / SnO2GN(A) obtained by drying SnO2 precursors in a forced-air environment and then calcining them, and Pt1Mo3 / SnO2GN(P) obtained without plasma treatment, the PtMo / SnO2GN of this invention shows better catalytic effect, stronger ethanol electrochemical oxidation performance, and enhanced resistance to CO poisoning. This composite material can be applied to direct ethanol fuel cells as a catalyst for ethanol electrooxidation, improving the electrooxidation efficiency of ethanol and further advancing the commercialization of direct ethanol fuel cell technology.

[0078] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a PtMo alloy catalyst supported on a SnO2GN composite support, characterized in that: Using SnO2GN composite support composed of SnO2 and graphene as catalyst support, and PtMo alloy as active component, PtMo alloy is supported on SnO2GN composite support to obtain PtMo / SnO2GN catalyst. The preparation process of the SnO2GN composite carrier is as follows: ammonia water is added dropwise to a soluble tin source aqueous solution, and the mixture is stirred continuously until no more sol is produced. The mixture is aged for 4 hours, centrifuged, and washed three times with water. Then, the resulting gel-like substance is added to an oxidized graphene suspension aqueous solution and stirred for 6 hours. The mixture is then allowed to stand for 24 hours. The mixed solution is then rotary evaporated at 80°C for 1 hour. The rotary-evaporated sample is placed in a vacuum tube furnace and calcined at 550°C for 2 hours to obtain the SnO2GN composite carrier. The concentration of the ammonia water is 0.4–0.6 mol / L, and the concentration of the tin source is 0.1 mol / L. The tin source is tin tetrachloride, and the graphene is graphene that has been oxidized by nitric acid or sulfuric acid vapor and H2O2. The graphene oxidation process is as follows: concentrated nitric acid or concentrated sulfuric acid is heated to generate acid vapor. The graphene is continuously heated in the concentrated acid vapor environment for acid treatment. After the treatment is stopped, the temperature of the graphene is maintained to dry the graphene treated with acid vapor. It is then washed until the pH of the filtrate is 7. It is then transferred to H2O2 solution for heating treatment, ultrasonicated for 1-3 hours, washed clean with deionized water, dried in a vacuum drying oven for 8-12 hours, and ground for 10-20 minutes to obtain oxidized graphene. The concentration of the H2O2 solution is 3-30%, the heat treatment temperature is 60℃, and the time is 10 minutes. After heat treatment, it is washed with deionized water at least 3 times. The concentrated nitric acid or concentrated sulfuric acid is heated separately from the graphene. The heating temperature of the concentrated nitric acid or concentrated sulfuric acid is 130-150°C. The graphene is continuously heated in the concentrated acid vapor environment at a temperature of 110-130°C for 7-9 hours. After the concentrated acid heating is stopped, the temperature of the graphene is maintained to dry the graphene treated with acid vapor at a temperature of 110-130°C for 24 hours. The process of supporting the PtMo alloy on the SnO2GN composite support is as follows: 0.1-0.2 mol / L ethylene glycol chloroplatinate solution and 0.1-0.2 mol / L ethylene glycol ammonium molybdate solution are mixed and stirred for 30 min. Then, the SnO2GN composite support is added, and the mixture is ultrasonicated and stirred for 30 min each to form a homogeneous solution. 3-5 wt.% NaOH / EG is added to adjust the pH to 9-10 to obtain a precursor solution. The precursor solution is heated to 160-180℃ in a microwave reactor at a power of 450-550 W and held for 90 s. After standing and cooling, the pH is adjusted to 5-7 using 3-5 wt.% dilute nitric acid aqueous solution and stirred for 30 min. The solution is washed until the filtrate is neutral, vacuum dried, and then treated with plasma in an Ar environment for 5-15 min to obtain the PtMo / SnO2GN catalyst. The PtMo / SnO2GN catalyst is used to catalyze the electro-oxidation reaction of ethanol in direct ethanol fuel cells.

2. The preparation method according to claim 1, characterized in that: The total mass fraction of PtMo alloy in the PtMo / SnO2GN catalyst is 3-10%, the atomic ratio of Pt to Mo in the PtMo alloy is 1:1 to 1:5, and the mass loading ratio of SnO2 is 5-20%.

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