PtxPdy / CeO2-CNTs electrocatalyst and preparation and application thereof

Abstract

The invention discloses a PtxPdy / CeO2-CNTs electrocatalyst as well as preparation and application thereof, and belongs to the field of catalysts. The preparation method of the electrocatalyst comprises the following steps: ultrasonically dispersing carbon nanotubes and soluble cerium salt in deionized water, adjusting the pH value by using a KOH solution, and carrying out suction filtration, washing and vacuum drying to obtain a composite carrier precursor; grinding the composite carrier precursor, putting into a tubular muffle furnace, roasting in an air atmosphere, and cooling to room temperature to obtain a CeO2-CNTs composite carrier; adding the CeO2-CNTs composite carrier into an ethylene glycol solution, ultrasonically dispersing uniformly, dropwise adding an H2PtCl6 solution and an H2PdCl4 solution, stirring, adjusting the pH value by using a NaOH solution, transferring into a stainless steel kettle containing a polytetrafluoroethylene lining, carrying out hydrothermal reaction, cooling to room temperature, washing for multiple times, and carrying out vacuum drying to obtain the catalyst. The electrocatalyst prepared by the invention has the advantages of larger electrochemical active area, high metal effective load rate, good stability, higher CO poisoning resistance and excellent methanol electrocatalytic oxidation performance.

Description

Technical Field

[0001] The present invention belongs to the field of composite alloy electrocatalysts, and is specifically a Pt x Pd y / CeO2-CNTs electrocatalyst and its preparation and application. Background Art

[0002] Methanol is the largest downstream chemical in coal chemical industry. Converting methanol into high value-added fine chemical intermediates or directly applying methanol to the energy field has objective economic benefits and practical significance. The development of fuel cell technology provides alternative solutions for energy conversion. Among them, direct methanol fuel cells (DMFCs) are energy conversion devices that directly convert chemical energy stored in methanol into electrical energy. They have the advantages of both batteries and internal combustion engines, and have the characteristics of simple structure, high methanol energy density, and green and pollution-free.

[0003] At present, Pt-based catalysts are still the main catalysts for commercial direct methanol fuel cells, but they are expensive, have slow anode kinetics, and are prone to the generation of CO during the oxidation of methanol by Pt-based catalysts. ads Problems such as the poisoning and deactivation of the catalyst due to the characteristic adsorption of intermediates and the poor stability of the catalyst in strongly acidic alkaline electrolytes limit its further commercial application. Analyzing the causes of the above problems, it is not difficult to conclude that the development of highly stable Pt-based catalysts is the key to the commercial application of direct methanol. At present, researchers have developed a variety of strategies to prepare efficient Pt-based electrocatalysts. The main strategies can be summarized as the preparation of multi-metal alloys, the synthesis of intermetallic compounds, and the construction of catalysts with special composition and morphology. However, effective strategies for the preparation of efficient electrocatalysts still need further research.

[0004] Therefore, in the face of unfavorable factors such as low activity, low effective loading rate of active metals, and poor stability of existing methanol electro-oxidation catalysts, it is necessary to specifically develop a methanol electro-oxidation alloy catalyst with high electrocatalytic performance, high effective loading rate of active metals, and good reaction stability. Summary of the invention

[0005] The present invention aims to provide a Pt x Pd y / CeO2-CNTs electrocatalyst and its preparation and application, the CeO2-CNTs composite carrier in the catalyst has high stability, and the Pt x Pd y The electronic structure of the alloy can be precisely adjusted, and the synthesized Pt x Pd y / CeO2-CNTs electrocatalyst has high activity and stability in methanol electro-oxidation catalysis as anode catalyst for direct methanol fuel cells in alkaline environment.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: In a first aspect, the present invention provides a Pt x Pd y / A method for preparing a CeO2-CNTs electrocatalyst, comprising: Step 1: ultrasonically disperse a certain amount of multi-walled carbon nanotubes (CNTs) and soluble cerium salt in deionized water, and continue stirring for a period of time to obtain a mixed solution A; Step 2: Adjust the pH value of the mixed solution A to 11-13 with a 1.0 mol / L KOH solution, continue stirring for a period of time and then filter, wash with a large amount of deionized water until neutral, and vacuum dry at 65° C. to obtain a composite carrier precursor; Step 3: Grind the composite carrier precursor and put it into a tubular muffle furnace, and calcine it for 2 hours in an air atmosphere with a heating rate controlled at 2°C / min. After cooling to room temperature, a CeO2-CNTs composite carrier is obtained; Step 4: Add the CeO2-CNTs composite carrier into the ethylene glycol (EG) solution and disperse it evenly by ultrasonication to obtain a mixed solution B; Step 5: Add 1.65 mL of 10 mmol / L H2PtCl6 solution and 1.65 mL of 10 mmol / L H2PdCl4 solution to the mixed solution B, stir for 4 hours, adjust the pH value to 12 with 0.5-2 mol / L NaOH solution, and then transfer to a stainless steel kettle lined with polytetrafluoroethylene for hydrothermal reaction at a temperature of 140-160°C for 4-6 hours. After cooling to room temperature, wash several times with a large amount of deionized water and anhydrous ethanol, and finally dry in vacuum at 70°C to obtain Pt x Pd y / CNTs-CeO2 electrocatalyst.

[0007] Furthermore, the soluble cerium salt in step 1 is cerium nitrite or cerium nitrate hexahydrate.

[0008] Preferably, the soluble cerium salt is cerium nitrate hexahydrate.

[0009] Furthermore, the calcination temperature in step 3 is 250-350°C.

[0010] Preferably, the calcination temperature is 250°C Furthermore, the content of CeO2-CNTs composite carrier in the mixed solution B in step 4 is 1-2 g / L, and the amount of ethylene glycol (EG) used is 30 mL.

[0011] Furthermore, in step 5, the hydrothermal reaction temperature is 140° C. and the time is 4 hours.

[0012] In a second aspect, the present invention provides a Pt x Pd y / CeO2-CNTs electrocatalyst, which is prepared by the above-mentioned preparation method, wherein the value of x is 1-2, and the value of y is 1-2.

[0013] In a third aspect, the present invention provides a Pt x Pd y / CeO2-CNTs electrocatalyst is used as an anode electrocatalyst for direct methanol fuel cells to participate in the electrocatalytic oxidation reaction of methanol in an alkaline environment. x Pd y / CeO2-CNTs electrocatalyst is modified on the surface of glassy carbon working electrode, and methanol is electrocatalyzed oxidized in an alkaline environment.

[0014] Furthermore, the potential range of the PtPd / CeO2-CNTs electrocatalyst for methanol electrocatalytic oxidation is -0.8V to 0.2V (vs. SCE), and the oxidation peak current is 5600.0 mA·mg -1 metal .

[0015] Compared with the prior art, the technical advantages and progress of the present invention are: The PtxPdy / CeO2-CNTs electrocatalyst of the present invention has a large electrochemical active area, a high metal effective loading rate, good stability, and exhibits a high resistance to CO poisoning, showing excellent methanol electrocatalytic oxidation performance; wherein the composite carrier CeO2-CNTs can provide more anchoring sites for the active metal, which can greatly improve the effective loading rate of the alloy; Pt x Pd y There is a strong metal-support interaction (SMSI) between the alloy and CeO2-CNTs. CeO2 adjusts the electronic structure properties of Pt and Pd, improves the adsorption energy of active metals and methanol, and Pt x Pd y The alloy exhibits a significant synergistic effect, and the catalytic activity and stability of methanol electrooxidation in an alkaline environment are greatly improved; at the same time, CeO2-CNTs are also beneficial to promote the dissociation of water in the electrolyte to form adsorbed OH ads , thereby improving the stability of the catalyst while ensuring the reaction activity.

[0016] The PtPd / CeO2-CNTs electrocatalyst prepared by the method of the present invention is characterized by X-ray diffraction (XRD), high-power transmission electron microscopy (TEM), electron energy spectrum (EDS-Mapping), X-ray photoelectron energy spectrum (XPS), etc., and combined with the electrochemical activity evaluation results in an alkaline environment, the essential reason for the high activity of the catalyst is revealed. The PtPd / CeO2-CNTs electrocatalyst prepared by the present invention has higher methanol electrocatalytic performance and stability than the catalyst prepared by ordinary alloys and carriers under the same conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The Pt loaded multi-walled carbon nanotubes prepared in Comparative Examples 1-5 of the present invention x Pd y Cyclic voltammetry (CV) curves of the alloy electrocatalyst in 1.0 M KOH + 1.0 M CH3OH solution; Figure 2 The Pt loaded multi-walled carbon nanotubes prepared in Comparative Examples 1-5 of the present invention x Pd y Chronoamperometric (CA) curve of the alloy electrocatalyst in 1.0 M KOH + 1.0 M CH3OH solution; Figure 3 is a cyclic voltammetry curve of Comparative Example 3 and Example 1 of the present invention in 1.0 M KOH + 1.0 M CH3OH; Figure 4 is a chronoamperometric curve (CA) diagram of Comparative Example 3 and Example 1 of the present invention in 1.0 M KOH + 1.0 M CH3OH; Figure 5 is the X-ray diffraction pattern (XRD) of Comparative Examples 1-5 and Example 1 of the present invention; wherein (a) is Pt2Pd1 / CNTs, Pt 1.7 Pd 1.3 / CNTs, PtPd / CNTs, Pt 1.3 Pd 1.7 / CNTs Pt1Pd2 / CNTs nanocatalysts; (b) PtPd / CNTs and PtPd / CeO2-CNTs XRD curve of nanocatalyst; Figure 6 These are the HRTEM spectra and EDS-Mapping spectra of Comparative Example 3 and Example 1 of the present invention. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is further described below through specific embodiments in combination with the accompanying drawings, but the implementation mode of the present invention is not limited thereto. Example 1

[0019] 200.0 mg CNTs and 125.8 mg Ce(NO3)3·6H2O were mixed and stirred in 125.0 mL H2O for 60 min, ultrasonically treated for 30 min, and then the pH was adjusted to 12 with 1.0 M KOH, stirred for 2 h, filtered, washed with a large amount of deionized water until neutral, and dried in a vacuum oven at 65 °C to obtain a composite carrier precursor, which was placed in a tubular muffle furnace, heated to 250 °C at a heating rate of 2 °C / min, and calcined for 2 h. After cooling to room temperature, a CeO2-CNTs composite carrier was obtained.

[0020] At room temperature, 50.0 mg of CeO2-CNTs composite carrier was weighed and uniformly dispersed in 30.0 mL of ethylene glycol solution by ultrasonic dispersion, and then 4.1 mL of 10 mmol / L H2PtCl6 solution and 4.1 mL of 10 mmol / L H2PdCl4 solution were added dropwise; the mixture was stirred for 6 h and then transferred to a stainless steel kettle lined with polytetrafluoroethylene at 140 ° C for 4 h. After cooling to room temperature, the mixture was filtered and washed with a large amount of deionized water and anhydrous ethanol to obtain PtPd / CeO2-CNTs electrocatalyst, Pt x Pd y The molar ratio of metal Pt to Pd in ​​the alloy is 1:1.

[0021] Comparative Example 1 Pt x Pd y Preparation of CNTs electrocatalysts At room temperature, 50.0 mg of multi-walled carbon nanotubes were weighed and uniformly dispersed in 30.0 mL of ethylene glycol solution by ultrasonic dispersion, and then 3.0 mL of 10 mmol / L H2PtCl6 solution and 6.1 mL of 10 mmol / L H2PdCl4 solution were added dropwise; the mixture was stirred for 6 h, and then transferred to a stainless steel kettle lined with polytetrafluoroethylene, reacted at 140 ° C for 4 h, and after cooling to room temperature, filtered and washed with a large amount of deionized water and anhydrous ethanol to obtain Pt x Pd y / CNTs electrocatalyst, Pt x Pd y The molar ratio of metal Pt to Pd in ​​the alloy is 2:1.

[0022] Comparative Example 2 Pt x Pd y Preparation of CNTs electrocatalysts At room temperature, 50.0 mg of multi-walled carbon nanotubes were weighed and uniformly dispersed in 30.0 mL of ethylene glycol solution by ultrasonic dispersion, and then 3.7 mL of 10 mmol / L H2PtCl6 solution and 4.8 mL of 10 mmol / L H2PdCl4 solution were added dropwise; the mixture was stirred for 6 h, and then transferred to a stainless steel kettle lined with polytetrafluoroethylene, reacted at 140 ° C for 4 h, and after cooling to room temperature, filtered and washed with a large amount of deionized water and anhydrous ethanol to obtain Pt x Pd y / CNTs electrocatalyst, Pt x Pd y The molar ratio of metal Pt to Pd in ​​the alloy is 1.7:1.3.

[0023] Comparative Example 3 Pt x Pd y Preparation of CNTs electrocatalysts At room temperature, 50.0 mg of multi-walled carbon nanotubes were weighed and uniformly dispersed in 30.0 mL of ethylene glycol solution by ultrasonic dispersion, and then 4.1 mL of 10 mmol / L H2PtCl6 solution and 4.1 mL of 10 mmol / L H2PdCl4 solution were added dropwise; the mixture was stirred for 6 h, and then transferred to a stainless steel kettle lined with polytetrafluoroethylene, reacted at 140 ° C for 4 h, and after cooling to room temperature, filtered and washed with a large amount of deionized water and anhydrous ethanol to obtain Pt x Pd y / CNTs electrocatalyst, Pt x Pd y The molar ratio of metal Pt to Pd in ​​the alloy is 1:1.

[0024] Comparative Example 4 Pt x Pd y Preparation of CNTs electrocatalysts At room temperature, 50.0 mg of multi-walled carbon nanotubes were weighed and uniformly dispersed in 30.0 mL of ethylene glycol solution by ultrasonic dispersion, and then 4.5 mL of 10 mmol / L H2PtCl6 solution and 3.4 mL of 10 mmol / L H2PdCl4 solution were added dropwise; the mixture was stirred for 6 h, and then transferred to a stainless steel kettle lined with polytetrafluoroethylene, reacted at 140 ° C for 4 h, and after cooling to room temperature, filtered and washed with a large amount of deionized water and anhydrous ethanol to obtain Pt x Pd y / CNTs electrocatalyst, Pt x Pd y The molar ratio of metal Pt to Pd in ​​the alloy is 1.3:1.7.

[0025] Comparative Example 5 Pt x Pd yPreparation of CNTs electrocatalysts At room temperature, 50.0 mg of multi-walled carbon nanotubes were weighed and uniformly dispersed in 30.0 mL of ethylene glycol solution by ultrasonic dispersion, and then 5.0 mL of 10 mmol / L H2PtCl6 solution and 2.5 mL of 10 mmol / L H2PdCl4 solution were added dropwise; the mixture was stirred for 6 h, and then transferred to a stainless steel kettle lined with polytetrafluoroethylene, reacted at 140 ° C for 4 h, and after cooling to room temperature, filtered and washed with a large amount of deionized water and anhydrous ethanol to obtain Pt x Pd y / CNTs electrocatalyst, Pt x Pd y The molar ratio of metal Pt to Pd in ​​the alloy is 1:2.

[0026] Comparative Example 6 At room temperature, 50.0 mg CNTs were weighed and uniformly dispersed in 30.0 mL ethylene glycol solution by ultrasonic dispersion, and then 6.4 mL 10 mmol / L H2PtCl6 precursor solution was added dropwise; the mixture was stirred for 6 h and then transferred to a stainless steel kettle lined with polytetrafluoroethylene at 140 ° C for 4 h. After cooling to room temperature, it was filtered and washed with a large amount of deionized water and anhydrous ethanol to obtain a Pt / CNTs electrocatalyst.

[0027] Comparative Example 7 At room temperature, 50.0 mg CNTs were weighed and uniformly dispersed in 30.0 mL ethylene glycol solution by ultrasonic dispersion, and then 11.7 mL 10 mmol / L H2PdCl4 solution was added dropwise; the mixture was stirred for 6 h, and then transferred to a stainless steel kettle lined with polytetrafluoroethylene, reacted at 140 ° C for 4 h, and after cooling to room temperature, filtered and washed with a large amount of deionized water and anhydrous ethanol to obtain a Pd / CNTs electrocatalyst.

[0028] Comparative Example 8 At room temperature, 50.0 mg of CNTs was weighed and uniformly dispersed in 30.0 mL of ethylene glycol solution by ultrasonic dispersion, immersed and stirred for 6 h, and then transferred to a stainless steel kettle lined with polytetrafluoroethylene, reacted at 140 ° C for 4 h. After cooling to room temperature, it was filtered and washed with a large amount of deionized water and anhydrous ethanol to obtain a CNTs electrocatalyst.

[0029] Comparative Example 9 At room temperature, 50.0 mg CeO2-CNTs were weighed and uniformly dispersed in 30.0 mL ethylene glycol solution by ultrasonic dispersion; the mixture was immersed and stirred for 6 h, and then transferred to a stainless steel kettle lined with polytetrafluoroethylene, reacted at 140 ° C for 4 h, and after cooling to room temperature, filtered and washed with a large amount of deionized water and anhydrous ethanol to obtain a CeO2-CNTs electrocatalyst.

[0030] Electrochemical performance test of electrocatalyst Before evaluating the electrocatalysts synthesized in Example 1 and Comparative Examples 1-9, the surface of the glassy carbon working electrode (GCE) was carefully polished with Al2O3 powder to make the surface regular, and then washed with anhydrous ethanol several times and used after drying.

[0031] Accurately weigh 2.0 mg of the catalyst prepared in Example 1 and Comparative Examples 1-9, and evenly disperse them by ultrasonic dispersion in a mixture containing 50 μL of 0.5% Nafion membrane solution, 450 μL of anhydrous ethanol and 500 μL of ultrapure water to obtain catalyst ink. Take 10 μL and drop it on the surface of the glassy carbon electrode. After it is completely dried, it is used as the working electrode for testing.

[0032] The conventional three-electrode system was used in the test, with a saturated calomel electrode (SCE) as the reference electrode and a platinum wire electrode as the counter electrode. The electrochemical performance of catalysts with different compositions was evaluated by cyclic voltammetry (CV), with an electrolyte of 1.0 M KOH + 1.0 MCH3OH, a scan rate of 50 mV / s, and a potential range of -0.9~0.3 V.

[0033] Figure 1 The supported Pt prepared in Comparative Examples 1-5 x Pd y Cyclic voltammetry (CV) curves of / CNTs electrocatalyst in 1.0 M KOH + 1.0 MCH3OH solution, with a scan rate of 50 mV / s and a potential range of -0.9-0.3 V. Figure 1 As shown in Figure 2, all catalysts have two obvious oxidation peaks for methanol electrocatalytic oxidation. Among them, the higher peak current density is 3480.0 mA·mg -1 metal .

[0034] Figure 2 The supported Pt prepared in Comparative Examples 1-5 x Pd y The chronoamperometric (it) curve of the / CNTs electrocatalyst at a constant potential of -0.2V in 1.0 M KOH + 1.0 MCH3OH solution, as shown in Figure 2 As shown in the figure, the current density of catalysts with different compositions is gradually increased due to the reaction in the initial stage. ads 、CH3OH ads 、COOH ads and CHO ads) occupied the active sites, causing the catalytic performance to decline rapidly and eventually remain stable. PtPd / CNTs showed the best stability and tolerance to carbonaceous intermediate poisoning, and could still maintain 956.1 mA·mg after 7200 s of reaction. −1 metal This suggests that the alloy structure with a specific composition not only enhances the activity but also improves the stability.

[0035] Figure 3 The cyclic voltammetry (CV) curves of the PtPd alloys loaded with different carriers prepared in Comparative Example 3 and Example 1 in 1.0 M KOH + 1.0 M CH3OH solution, with a scan rate of 50 mV / s and a potential range of -0.9-0.3 V, as shown in FIG. Figure 3 As shown in Figure 2, the mass specific activity of PtPd / CeO2-CNTs reaches 5600 mA·mg -1 metal , which is about 1.60 times the mass specific activity of PtPd / CNTs.

[0036] Figure 4 The chronoampere (it) curves of the PtPd alloys loaded with different carriers prepared in Comparative Example 3 and Example 1 at -0.2 V in 1.0 MKOH + 1.0 M CH3OH solution. PtPd / CeO2-CNTs showed higher stability and could still maintain 1810.2 mA·mg after 7200 s. -1 metal This is because the content of metallic PtPd in ​​PtPd / CeO2-CNTs is significantly higher than that in PtPd / CNTs due to the interaction between PtPd alloy and the composite support CeO2-CNTs.

[0037] Figure 5 The XRD patterns of PtPd alloys (PtPd / CNTs-3 and PtPd / CeO2-CNTs) loaded with different carriers prepared in Comparative Example 3 and Example 1. The diffraction peak at 2θ=26° is the (002) crystal plane of graphite carbon. x Pd yThe diffraction peaks appeared at 2θ=40.0°, 46.5°, and 67.7°, and the peaks were symmetrical, corresponding to the (111), (200), and (220) planes of the face-centered cubic (fcc) structure. The results showed that all catalysts successfully synthesized well-alloyed PtPd nanostructures. In PtPd / CeO2-CNTs, the diffraction peaks at 2θ=28.7, 32.7°, 47.3°, 56.2°, 69.1°, 77.7°, and 88.4° corresponded to the (111), (200), (220), and (311) crystal planes of the face-centered cubic (fcc) structure of CeO2, respectively. In addition, compared with PtPd / CNTs, the diffraction peaks of PtPd / CeO2-CNTs became broader, indicating that the addition of cerium led to the appearance of smaller nanoscale PtPd particles.

[0038] Figure 6 The high magnification transmission electron microscopy (HRTEM) images and energy spectrum (EDS-Mapping) images of the PtPd alloys (PtPd / CNTs-3 and PtPd / CeO2-CNTs) loaded with different carriers prepared in Comparative Example 3 and Example 1 are shown. Figure 6 As shown in Figure 2, the PtPd alloy with a size of 2.00±0.45 nm is very uniformly distributed on the CNTs. The HRTEM image of the PtPd alloy nanoparticles shows a lattice spacing of 0.225 nm, corresponding to the PtPd (111) plane. In contrast, PtPd is more densely anchored on the CeO2-CNTs surface and has a smaller size distribution of 1.96±0.37nm; the lattice spacings of 0.225 nm and 0.256 nm correspond to the (111) and (200) planes of PtPd, respectively. The lattice spacings are 0.322 nm and 0.276 nm, corresponding to the (111) and (200) planes of CeO2, respectively. The EDS-Mapping results show that the metal Pt and Pd are uniformly distributed on the support. At the same time, there is a partial overlap between the PtPd and Ce elements, which indicates that the existence of the PtPd / CeO2 / CNTs interface promotes the occurrence of electrocatalytic MOR through a synergistic mechanism.

[0039] The test results show that for Pt x Pd y / CNTs electrocatalyst, when the molar ratio of Pt to Pd is 1:1, it has the best electrocatalytic oxidation performance for methanol, and the mass specific activity of the catalyst is 3480mA·mg -1 metal .

[0040] The mass specific activity range of the alloy catalysts prepared in Example 1 and Comparative Examples 1-5 for methanol oxidation is: 1541.1 ~ 3480.0 mA·mg -1metal The activity and stability are higher than those of the single metal Pt / CNTs in comparative example 6 (486.1 mA·mg -1 metal ) and the single metal Pd / CNTs in comparative example 7 (740.5 mA·mg -1 metal The essential reason why the catalyst of comparative example 3 (Pt1Pd1 / CNTs-3) has high activity is that Pt and Pd form an alloy structure, and the synergistic effect between the two metals promotes the dissociation of more OH with strong oxidizing properties in the electrolyte. ads , further accelerating the oxidative removal of carbonaceous intermediates adsorbed on the active surface. The mass specific activity of Pt1Pd1 / CeO2-CNTs-6 prepared in Example 1 is higher, reaching 5600.0mA·mg -1 metal This is because there is a strong interaction between the metal and the support between the PtPd alloy and CeO2-CNTs. The presence of CeO2 not only further adjusts the electronic structure of the PtPd alloy, but also presents more active metallic Pt 0 Pd 0 , and can also promote the electrolysis of the reaction solution and produce more OH under lower reaction conditions. ads , thereby oxidizing and removing the carbonaceous intermediates generated by the reaction to the maximum extent. In addition, the reduced CNTs carrier (Comparative Example 8) and CeO2-CNTs (Comparative Example 9) have no electrocatalytic activity for methanol, indicating that Pt plays a leading role in methanol oxidation. x Pd y alloy. For Pt2Pd1 / CNTs-1, Pt 1.7 Pd 1.3 / CNTs-2,Pt1Pd1 / CNTs-3,Pt 1.3 Pd 1.7 / CNTs-4, Pt1Pd2 / CNTs-5 Pt1Pd1 / CeO2-CNTs (Comparative Examples 1-5 and Example 1), Pt / CNTs (Comparative Example 1), and Pd / CNTs (Comparative Example 2) have potentials of about -0.2 V for methanol electrocatalytic oxidation, but different starting potentials and peak current densities. The specific values ​​are shown in Table 1.

[0041] Table 1 Performance test results of catalysts prepared in Example 1 and Comparative Examples 1-9 catalyst Methanol oxidation potential (V) Current density (mA / mg) Comparative Example 1 <![CDATA[Pt2Pd1 / CNTs]]> -0.189 1541.1 Comparative Example 2 <![CDATA[Pt 1.7 Pd 1.3 / CNTs]]> -0.182 2488.3 Comparative Example 3 PtPd / CNTs -0.198 3480.0 Comparative Example 4 <![CDATA[Pt 1.3 Pd 1.7 / CNTs]]> -0.186 2783.3 Comparative Example 5 <![CDATA[Pt1Pd2 / CNTs]]> -0.198 1805.0 Example 1 <![CDATA[PtPd / CeO2-CNTs]]> -0.192 5600 Comparative Example 6 Pt / CNTs -0.26 486.1 Comparative Example 7 Pd / CNTs -0.174 740.5 Comparative Example 8 CNTs / / Comparative Example 9 <![CDATA[CeO2-CNTs]]> / / The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A Pt x Pd y / CeO2-CNTs electrocatalyst preparation method, characterized in that, include: Step 1: ultrasonically disperse a certain amount of multi-walled carbon nanotubes (CNTs) and soluble cerium salt in deionized water, and continue stirring for a period of time to obtain a mixed solution A; Step 2: Adjust the pH value of the mixed solution A to 11-13 with a 1.0 mol / L KOH solution, continue stirring for a period of time and then filter, wash with a large amount of deionized water until neutral, and vacuum dry at 65° C. to obtain a composite carrier precursor; Step 3: Grind the composite carrier precursor and put it into a tubular muffle furnace, and calcine it for 2 hours in an air atmosphere with a heating rate controlled at 2°C / min. After cooling to room temperature, a CeO2-CNTs composite carrier is obtained; Step 4: Add the CeO2-CNTs composite carrier into the ethylene glycol (EG) solution and disperse it evenly by ultrasonication to obtain a mixed solution B; Step 5: Add 1.65 mL of 10 mmol / L H2PtCl6 solution and 1.65 mL of 10 mmol / L H2PdCl4 solution to the mixed solution B, stir for 4 hours, adjust the pH value to 12 with 0.5-2 mol / L NaOH solution, and then transfer to a stainless steel kettle lined with polytetrafluoroethylene for hydrothermal reaction at a temperature of 140-160°C for 4-6 hours. After cooling to room temperature, wash with a large amount of deionized water and anhydrous ethanol several times, and finally dry in vacuum at 70°C to obtain Pt x Pd y / CNTs-CeO2 electrocatalyst.

2. A Pt as claimed in claim 1 x Pd y / CeO2-CNTs electrocatalyst preparation method, characterized by: The soluble cerium salt described in step 1 is cerium nitrite or cerium nitrate hexahydrate.

3. A Pt as claimed in claim 2 x Pd y / CeO2-CNTs electrocatalyst preparation method, characterized by: The soluble cerium salt is cerium nitrate hexahydrate.

4. A Pt as claimed in claim 1 x Pd y / CeO2-CNTs electrocatalyst preparation method, characterized by: The calcination temperature in step 3 is 250-350°C.

5. A Pt as claimed in claim 4 x Pd y / CeO2-CNTs electrocatalyst preparation method, characterized by: The calcination temperature is 250°C.

6. A Pt as claimed in claim 1 x Pd y / CeO2-CNTs electrocatalyst preparation method, characterized by: In step 4, the content of CeO2-CNTs composite carrier in the mixed solution B is 1-2 g / L, and the amount of ethylene glycol (EG) used is 30 mL.

7. A Pt as claimed in claim 1 x Pd y / CeO2-CNTs electrocatalyst preparation method, characterized by: The hydrothermal reaction temperature in step 5 is 140° C. and the time is 4 h.

8. A Pt x Pd y / CeO2-CNTs electrocatalyst is a Pt x Pd y / CeO2-CNTs electrocatalyst is prepared by a method for preparing the electrocatalyst, wherein: The value of x is 1 to 2, and the value of y is 1 to 2.

9. A Pt x Pd y / CeO2-CNTs electrocatalyst is used as anode electrocatalyst of direct methanol fuel cell to participate in methanol electrocatalytic oxidation reaction in alkaline environment.

10. The use according to claim 9, characterized in that: The potential range of the PtPd / CeO2-CNTs electrocatalyst for methanol electrocatalytic oxidation is -0.8V to 0.2V (vs. SCE), and the oxidation peak current is 5600.0 mA·mg -1 metal .

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