Preparation method of cerium oxide partially coated platinum copper nanocube composite electrocatalyst

Abstract

The present invention discloses a method for preparing a composite electrocatalyst of platinum copper nanocubes partially coated with cerium oxide, wherein copper-doped cerium oxide is anchored on the surface of a carbon substrate in advance to obtain a copper-doped cerium oxide / carbon carrier, and then a platinum precursor is adsorbed on the surface of the copper-doped cerium oxide / carbon carrier, and then a high-pressure solvent thermal reaction is performed using N,N-dimethylformamide as a solvent and a reducing agent. During the high-pressure solvent thermal reaction, the platinum precursor is reduced to generate platinum nanocubes; the Cu in the carrier 2+ It will also move into the platinum nanocube lattice and be reduced to form platinum-copper alloy phase nanocubes. The present invention cleverly utilizes the SMSI effect induced by solvent heat, and simply realizes the reduction of platinum precursor, partial coating of cerium oxide and the formation of platinum-copper alloy phase at the same time, greatly improving the MOR activity, stability and CO poisoning resistance of the catalyst, and has universal promotion.

Description

Technical Field

[0001] The invention relates to the technical field of energy chemical materials, and in particular to a method for preparing a composite electrocatalyst of platinum-copper nanocubes partially coated with cerium oxide. Background Art

[0002] As a renewable energy conversion device, direct methanol fuel cells (DMFCs) have outstanding advantages such as wide fuel sources, convenient storage and transportation, good safety and easy operation. They are indispensable for the development and deployment of the gasoline-hydrogen transition period. Methanol oxidation reaction (MOR) electrocatalysts are key materials in the anode of DMFCs, which directly affect the cost, performance and service life of the entire battery. Highly dispersed Pt nanoparticles supported by high specific surface area carbon carriers (Pt / C) are currently the main MOR catalysts used. However, due to the large difference in electronic properties and weak interaction between carbon carriers and Pt in this type of catalyst, Pt nanoparticles can easily migrate and aggregate on the surface of the carrier, resulting in a decrease in catalyst activity and stability; and traditional carbon carriers have almost no modification to the electronic structure of Pt, and cannot produce any synergistic catalytic effect. In addition, the MOR on single metal Pt is mainly in the form of toxic intermediates CO ads The indirect reaction pathway (also called the CO pathway) generated by ads The strong adsorption on Pt will seriously damage the subsequent catalytic process of the Pt site and reduce the MOR activity. Therefore, it is of great significance to develop an efficient, stable and CO-resistant MOR electrocatalyst.

[0003] In recent years, a lot of work has been done at home and abroad to address the lack of activity, stability and poor resistance to CO poisoning of MOR electrocatalysts. The research content mainly focuses on alloying or adding metal oxides and other co-catalysts. Chinese invention patent CN109888317A discloses "a direct methanol fuel cell catalyst and its preparation method", which prepares a platinum-indium alloy catalyst with activated carbon as a carrier. However, the preparation process of this type of alloy catalyst is complicated, and it still faces serious problems such as CO poisoning and easy agglomeration of nanoparticles. Chinese invention patent CN101306365A discloses "a composite anode electrocatalyst for direct methanol fuel cells", which synthesizes nanoscale doped metal oxide M on a high specific surface area carbon surface. 1-X N X O 2 (M is Zr or Ce, N is a transition metal or alkaline earth metal), to obtain a metal oxide M 1-X N X O 2 The carrier of modified carbon is then reduced by ethylene glycol reduction method on the surface of the carrier. In the obtained composite catalyst, the doped metal oxide M 1-X N X O2 It plays a role in promoting catalysis. The rich oxygen vacancy defects caused by doping help water to generate active oxygen-containing species (such as OH) on the crystal surface. ads ); These oxygen-containing species will overflow to the Pt surface and react with CO during the MOR process. ads etc., thereby accelerating the CO ads The oxidation and desorption of toxic substances such as methanol and methanol can release the active sites of platinum, allowing the platinum metal to re-adsorb methanol and carry out subsequent reactions, thereby accelerating the MOR kinetic process. However, the preparation process of this technology is also relatively cumbersome, and the problem of insufficient catalyst stability caused by the migration and aggregation of Pt nanoparticles has not been solved. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst in view of the shortcomings of the existing methanol oxidation electrocatalyst such as insufficient activity, stability and poor CO poisoning resistance. The present invention pre-anchors copper doped cerium oxide on the surface of a carbon substrate to obtain a copper doped cerium oxide / carbon carrier, and then adsorbs a platinum precursor on the surface of the copper doped cerium oxide / carbon carrier, and then performs a high-pressure solvothermal reaction using N,N-dimethylformamide as a solvent and a reducing agent. During the high-pressure solvothermal reaction, the following changes will occur: the platinum precursor will be reduced to form platinum nanocubes; CeO 2 The redox reaction between the platinum and the CeO 2-x , while CeO 2-x will migrate to the surface of the platinum nanocubes, a phenomenon known as strong metal-support interaction (SMSI); the Cu 2+ It will also move into the platinum nanocube lattice and be reduced to form platinum-copper alloy phase nanocubes. The present invention cleverly utilizes the SMSI effect induced by solvent heat, and simply realizes the reduction of platinum precursor, partial coating of cerium oxide and the formation of platinum-copper alloy phase at the same time, greatly improving the MOR activity, stability and CO poisoning resistance of the catalyst.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] The method for preparing a composite electrocatalyst of platinum-copper nanocubes partially coated with cerium oxide comprises the following steps:

[0007] a. Preparation of copper-doped cerium oxide / carbon

[0008] Carbon powder and cerium metal salt are weighed according to the mass ratio of Vulcan XC-72 carbon powder and cerium metal salt of 1:0.2-0.4, and copper metal salt is weighed according to the molar ratio of cerium metal salt: copper metal salt of 1:0.1-2.0; the weighed carbon powder, cerium metal salt and copper metal salt are dispersed in 40 ml of distilled water, and ultrasonically stirred for 10-30 hours to obtain a mixed solution A; 130-275 mg of sodium hydroxide is weighed and dissolved in 10 ml of distilled water to obtain a sodium hydroxide solution; the sodium hydroxide solution is added dropwise to the above mixed solution A to obtain a mixed solution B after the dropwise addition is completed; the mixed solution B is continuously stirred at room temperature for 10-15 hours, filtered and dried to obtain copper-doped cerium oxide / carbon;

[0009] b. Preparation of Pt-Cu nanocubes partially coated with Cerium Oxide / Copper-doped Cerium Oxide / Carbon composite electrocatalyst

[0010] Weigh 80 mg of the carbon-supported Cu prepared in step a 2+ Doped CeO 2 Ultrasonic dispersion is carried out in 50-100 ml of N,N-dimethylformamide, and then 40-60 mg of platinum precursor is added, and stirring is continued at room temperature for 20-30 hours; the stirred solution is transferred to a high-pressure reactor and reacted at 120-150° C. for 20-35 hours; after the reactor is naturally cooled to room temperature, the product is filtered and washed with a mixture of ethanol and distilled water, dried at 60-70° C. for 8 hours, and ground to obtain a cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst.

[0011] The cerium metal salt is one of cerium nitrate hexahydrate and cerium chloride; the copper metal salt is one of copper nitrate trihydrate and copper chloride; and the platinum precursor is one of platinum acetylacetonate and chloroplatinic acid.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. The preparation of PtCu alloy nanocubes, the coating of cerium oxide on the surface of nanocubes and the construction of strong metal-support interaction are achieved in one step by using a simple solvothermal reaction, which is practical for future large-scale production applications;

[0014] 2. The cerium oxide material partially coated on the surface of the platinum-copper nanocubes can effectively prevent the migration, agglomeration and growth of platinum particles on the carrier, thereby improving the stability of the catalyst;

[0015] 3. The copper-doped cerium oxide on the carbon surface is rich in oxygen vacancy defects, which can dissociate water at low potential to generate active oxygen-containing species (such as OH ads ), in the MOR process OH ads will overflow to the adjacent Pt, thus accelerating the CO adsThe oxidation and desorption of platinum synergistically enhance the ability of platinum to resist CO poisoning;

[0016] 4. The alloying of copper and platinum will significantly optimize the electronic and geometric structure of platinum, further improving the performance of platinum-catalyzed MOR.

[0017] The method of the present invention is simple and easy to implement, has low production cost, and has universal applicability, and can be extended to the large-scale preparation of other metal / doped oxide / carbon systems. The cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst prepared by the present invention has excellent MOR stability and activity, and can replace the existing commercial Pt / C catalyst for direct methanol fuel cells. The direct methanol fuel cell manufactured by the present invention can be widely used in electric vehicles, various spacecraft, portable electronic devices such as cameras, laptops, electric toys, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Transmission electron microscope (TEM) image of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst prepared in Example 1 ( Figure 1 a) and particle size distribution diagram ( Figure 1 b);

[0019] Figure 2 This is a high magnification transmission electron microscopy (HRTEM) image of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst obtained in Example 1;

[0020] Figure 3 Transmission electron microscope (TEM) image of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst prepared in Example 2 ( Figure 3 a) and particle size distribution diagram ( Figure 3 b);

[0021] Figure 4 This is a high magnification transmission electron microscopy (HRTEM) image of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst obtained in Example 2;

[0022] Figure 5 Transmission electron microscope (TEM) image of the cerium oxide partially coated platinum nanocube / cerium oxide / carbon composite electrocatalyst obtained in comparison with experiment 1 ( Figure 5 a) and particle size distribution diagram ( Figure 5 b);

[0023] Figure 6 High magnification transmission electron microscopy (HRTEM) image of the platinum nanocube / cerium oxide / carbon composite electrocatalyst partially coated with cerium oxide prepared in comparison with Experiment 1;

[0024] Figure 7 This is a high-angle annular dark-field scanning electron microscopy image of the cerium oxide partially coated platinum copper nanocube / copper-doped cerium oxide / carbon composite electrocatalyst prepared in Example 1 ( Figure 7 g) and element energy spectrum ( Figure 7 hl);

[0025] Figure 8 Elemental energy spectrum of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst obtained in Example 3;

[0026] Fig. 9 Elemental energy spectrum of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst obtained in Example 4;

[0027] Fig.10 High-angle annular dark-field scanning electron microscopy (a) and elemental energy spectra (bf) of the cerium oxide partially coated platinum nanocube / cerium oxide / carbon composite electrocatalyst prepared in comparison with Experiment 1;

[0028] Fig.11 X-ray diffraction patterns of the copper-doped cerium oxide / carbon and cerium oxide partially coated platinum copper nanocubes / copper-doped cerium oxide / carbon composite electrocatalysts prepared in Example 1, the cerium oxide partially coated platinum nanocubes / cerium oxide / carbon composite electrocatalyst prepared in Comparative Experiment 1, and the commercial Pt / C catalyst of Johnson-Mathey Company, UK, in Comparative Experiment 2;

[0029] Fig.12 The electron paramagnetic resonance spectra of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst prepared in Example 1 and the cerium oxide partially coated platinum nanocube / cerium oxide / carbon composite electrocatalyst prepared in Comparative Experiment 1;

[0030] Fig.13 The methanol oxidation activity test graph of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst prepared in Example 1, the cerium oxide partially coated platinum nanocube / cerium oxide / carbon composite electrocatalyst prepared in Comparative Experiment 1, and the commercial Pt / C catalyst of Johnson-Mathey Company, UK, in Comparative Experiment 2;

[0031] Fig.14 This is a test graph of methanol oxidation activity of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst prepared in Examples 2 to 4;

[0032] Fig.15The anti-CO poisoning performance test graphs of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst prepared in Example 1, the cerium oxide partially coated platinum nanocube / cerium oxide / carbon composite electrocatalyst prepared in Comparative Experiment 1, and the commercial Pt / C catalyst of Johnson-Mathey Company in the UK;

[0033] Fig.16 This is a stability test curve of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst prepared in Example 1;

[0034] Fig.17 The stability test curve of the platinum nanocube / cerium oxide / carbon composite electrocatalyst partially coated with cerium oxide was obtained for comparison with Experiment 1;

[0035] Fig.18 This is the stability test curve of the commercial Pt / C catalyst of Johnson-Mathey Company in the UK for comparative experiment 2. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with specific embodiments:

[0037] Example 1

[0038] (1) Preparation of copper-doped cerium oxide / carbon

[0039] Weigh carbon powder and cerium nitrate hexahydrate according to the mass ratio of VulcanXC-72 carbon powder and cerium nitrate hexahydrate of 1:0.3, and weigh copper nitrate trihydrate according to the molar ratio of cerium nitrate hexahydrate: copper nitrate trihydrate of 1:1; disperse the weighed carbon powder, cerium nitrate hexahydrate and copper nitrate trihydrate in 40 ml of distilled water, and stir ultrasonically for 24 hours to obtain a mixed solution A. Weigh 193 mg of sodium hydroxide and dissolve it in 10 ml of distilled water to obtain a sodium hydroxide solution. Add the sodium hydroxide solution dropwise to the above mixed solution A, and obtain a mixed solution B after the addition is complete. Continue to stir the mixed solution B at room temperature for 12 hours, filter and dry to obtain copper-doped cerium oxide / carbon.

[0040] (2) Preparation of Cerium Oxide Partially Coated Platinum-Copper Nanocubes / Copper-Doped Cerium Oxide / Carbon Composite Electrocatalyst

[0041] Weigh 80 mg of the carbon-supported Cu prepared in step (1) 2+ Doped CeO 2Ultrasonic dispersion was performed in 70 ml of N,N-dimethylformamide, and then 40 mg of acetylacetonate platinum was added and stirred at room temperature for 24 hours. The stirred solution was transferred to a high-pressure reactor and reacted at 140°C for 22 hours. After the reactor was naturally cooled to room temperature, the product was filtered and washed with a mixture of ethanol and distilled water, dried at 60°C for 8 hours, and ground to obtain a cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst.

[0042] (3) Transmission electron microscopy test and particle size statistics of cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst

[0043] The prepared cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst was tested by transmission electron microscopy. Figure 1 Transmission electron microscope (TEM) image in a. Figure 1 The particle size of the particles in a is calculated by particle size statistics. Figure 1 Particle size distribution diagram in b.

[0044] (4) High-magnification transmission electron microscopy test of cerium oxide partially coated platinum copper nanocubes / copper-doped cerium oxide / carbon composite electrocatalyst

[0045] The prepared cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst was tested by high magnification transmission electron microscopy. Figure 2 High magnification transmission electron microscopy (HRTEM) photograph.

[0046] (5) High-angle annular dark-field scanning electron microscopy test and elemental energy spectrum analysis of cerium oxide partially coated platinum copper nanocubes / copper-doped cerium oxide / carbon composite electrocatalyst

[0047] The prepared cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst was tested by high angle annular dark field scanning electron microscopy. Figure 7 g, yes Figure 7 g was analyzed by elemental energy spectrum to obtain Figure 7 hl.

[0048] (6) X-ray diffraction test of cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst

[0049] The prepared cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst was subjected to an X-ray diffraction (XRD) pattern, such as Fig.11 As shown in the middle curve 1.

[0050] (7) X-ray diffraction test of copper-doped cerium oxide / carbon

[0051] The prepared copper-doped cerium oxide / carbon was subjected to an X-ray diffraction (XRD) spectrum, such as Fig.11 As shown in the middle curve 2.

[0052] (8) Electron paramagnetic resonance spectroscopy test of cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst

[0053] The prepared cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst was subjected to an electron paramagnetic resonance instrument to obtain an electron paramagnetic resonance spectrum (EPR), such as Fig.12 As shown in the middle curve 1.

[0054] (9) Methanol oxidation performance test of cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst in a three-electrode system

[0055] Weigh 2 mg of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst prepared in step (2) and add it to 800 μL of isopropanol. After 10 minutes of ultrasonic oscillation and uniform dispersion, a micro-injector draws 10 μL and evenly coats it on the glassy carbon rotating disk electrode and keeps it at 60°C for 2 hours. This is used as the working electrode, and a platinum ring electrode and a silver / silver chloride (Ag / AgCl) electrode are used as the auxiliary electrode and the reference electrode, respectively. The cyclic scanning voltammetry curve is tested in a nitrogen-saturated 0.5M / L sulfuric acid and 0.5M / L methanol mixed aqueous solution, with a scanning rate of 50 mV / s and a scanning range of -0.1489 to 1.001 V (relative to the silver / silver chloride electrode). Fig.13 As shown in the middle curve 1.

[0056] (10) Anti-CO poisoning performance test of cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst

[0057] 2 mg of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst prepared in step (2) was weighed and added to 800 μL of isopropanol. After being dispersed evenly by ultrasonic oscillation for 10 minutes, 10 μL was drawn by a microinjector and evenly coated on a glassy carbon rotating disk electrode and kept at 60°C for 2 hours. This was used as a working electrode and placed in a 0.5M / L sulfuric acid solution. High-purity CO gas was continuously flushed on its surface for 30 minutes. Then, a platinum ring electrode and a silver / silver chloride (Ag / AgCl) electrode were used as auxiliary electrodes and reference electrodes, respectively. Cyclic scanning voltammetry curves were tested in a fresh nitrogen-saturated 0.5M / L sulfuric acid solution. The scanning rate was 50 mV / s and the scanning range was -0.1489 to 1.001 V (relative to the silver / silver chloride electrode), as shown in curve 1 in FIG15 .

[0058] (11) Stability test of cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst

[0059] Weigh 2 mg of the cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst prepared in step (2) and add it to 800 μl of anhydrous ethanol. After ultrasonic oscillation for 10 minutes to disperse evenly, a micro-injector draws 10 μl and evenly coats it on the glassy carbon rotating disk electrode and keeps it at 60°C for 2 hours. This is used as the working electrode, and the platinum ring electrode and silver / silver chloride (Ag / AgCl) electrode are used as the auxiliary electrode and reference electrode respectively. The mixed aqueous solution of 0.5M / L sulfuric acid and 0.5M / L methanol saturated with nitrogen is scanned 600 times. The scanning rate is 50mV / s, and the scanning range is -0.1489 to 1.001 volts (relative to the silver / silver chloride electrode). The test results are as follows: Fig.16 As shown, the scanning circle number of curve A is the 1st circle, and the scanning circle number of curve B is the 600th circle.

[0060] Example 2

[0061] (1) Preparation of copper-doped cerium oxide / carbon

[0062] Weigh carbon powder and cerium nitrate hexahydrate according to the mass ratio of VulcanXC-72 carbon powder and cerium nitrate hexahydrate of 1:0.2, and weigh copper nitrate trihydrate according to the molar ratio of cerium nitrate hexahydrate: copper nitrate trihydrate of 1:0.2; disperse the weighed carbon powder, cerium nitrate hexahydrate and copper nitrate trihydrate in 40 ml of distilled water, and stir ultrasonically for 24 hours to obtain a mixed solution A. Weigh 130 mg of sodium hydroxide and dissolve it in 10 ml of distilled water to obtain a sodium hydroxide solution. Add the sodium hydroxide solution dropwise to the above mixed solution A, and obtain a mixed solution B after the addition is complete. Continue to stir the mixed solution B at room temperature for 12 hours, filter and dry to obtain copper-doped cerium oxide / carbon.

[0063] (2) Preparation of Cerium Oxide Partially Coated Platinum-Copper Nanocubes / Copper-Doped Cerium Oxide / Carbon Composite Electrocatalyst

[0064] Weigh 80 mg of the carbon-supported Cu prepared in step (1) 2+ Doped CeO 2 Ultrasonic dispersion was performed in 70 ml of N,N-dimethylformamide, and then 40 mg of acetylacetonate platinum was added and stirred at room temperature for 24 hours. The stirred solution was transferred to a high-pressure reactor and reacted at 120°C for 20 hours. After the reactor was naturally cooled to room temperature, the product was filtered and washed with a mixture of ethanol and distilled water, dried at 60°C for 8 hours, and ground to obtain a cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst.

[0065] (3) Transmission electron microscopy test and particle size statistics of cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst

[0066] The prepared cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst was tested by transmission electron microscopy. Figure 3 Transmission electron microscope (TEM) image in a. Figure 3 The particle size of the particles in a is calculated by particle size statistics. Figure 3 Particle size distribution diagram in b.

[0067] (4) High-magnification transmission electron microscopy test of cerium oxide partially coated platinum copper nanocubes / copper-doped cerium oxide / carbon composite electrocatalyst

[0068] The prepared cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst was tested by high magnification transmission electron microscopy. Figure 4 High magnification transmission electron microscopy (HRTEM) photograph.

[0069] (5) Methanol oxidation performance test of cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst in a three-electrode system

[0070] This step is the same as step (9) in Example 1, and the result is as follows Fig.14 As shown in curve 1.

[0071] Example 3

[0072] (1) Preparation of copper-doped cerium oxide / carbon

[0073] Weigh carbon powder and cerium nitrate hexahydrate according to the mass ratio of VulcanXC-72 carbon powder and cerium nitrate hexahydrate of 1:0.3, and weigh copper nitrate trihydrate according to the molar ratio of cerium nitrate hexahydrate: copper nitrate trihydrate of 1:0.4; disperse the weighed carbon powder, cerium nitrate hexahydrate and copper nitrate trihydrate in 40 ml of distilled water, and stir ultrasonically for 24 hours to obtain a mixed solution A. Weigh 193 mg of sodium hydroxide and dissolve it in 10 ml of distilled water to obtain a sodium hydroxide solution. Add the sodium hydroxide solution dropwise to the above mixed solution A, and obtain a mixed solution B after the addition is complete. Continue to stir the mixed solution B at room temperature for 12 hours, filter and dry to obtain copper-doped cerium oxide / carbon.

[0074] (2) Preparation of Cerium Oxide Partially Coated Platinum-Copper Nanocubes / Copper-Doped Cerium Oxide / Carbon Composite Electrocatalyst

[0075] Weigh 80 mg of the carbon-supported Cu prepared in step (1) 2+ Doped CeO 2Ultrasonic dispersion was performed in 70 ml of N,N-dimethylformamide, and then 40 mg of acetylacetonate platinum was added and stirred at room temperature for 24 hours. The stirred solution was transferred to a high-pressure reactor and reacted at 140°C for 22 hours. After the reactor was naturally cooled to room temperature, the product was filtered and washed with a mixture of ethanol and distilled water, dried at 60°C for 8 hours, and ground to obtain a cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst.

[0076] (3) Elemental spectroscopy analysis of cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst

[0077] The prepared cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst was analyzed by elemental energy spectrum. Figure 8 .

[0078] (4) Methanol oxidation performance test of cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst in a three-electrode system

[0079] This step is the same as step (9) in Example 1, and the result is as follows Fig.14 As shown in curve 2.

[0080] Example 4

[0081] (1) Preparation of copper-doped cerium oxide / carbon

[0082] Weigh carbon powder and cerium chloride according to the mass ratio of VulcanXC-72 carbon powder and cerium chloride of 1:0.4, and weigh copper chloride according to the molar ratio of cerium chloride: copper chloride of 1:1.5; disperse the weighed carbon powder, cerium chloride and copper chloride in 40 ml of distilled water, and stir ultrasonically for 3 hours to obtain a mixed solution A. Weigh 275 mg of sodium hydroxide and dissolve it in 10 ml of distilled water to obtain a sodium hydroxide solution. Add the sodium hydroxide solution dropwise to the above mixed solution A, and obtain a mixed solution B after the addition is complete. Continue to stir the mixed solution B at room temperature for 15 hours, filter and dry it to obtain copper-doped cerium oxide / carbon.

[0083] (2) Preparation of Cerium Oxide Partially Coated Platinum-Copper Nanocubes / Copper-Doped Cerium Oxide / Carbon Composite Electrocatalyst

[0084] Weigh 80 mg of the carbon-supported Cu prepared in step (1) 2+ Doped CeO 2Ultrasonic dispersion was performed in 100 ml of N,N-dimethylformamide, and then 60 mg of chloroplatinic acid was added and stirred at room temperature for 30 hours. The stirred solution was transferred to a high-pressure reactor and reacted at 150°C for 20 hours. After the reactor was naturally cooled to room temperature, the product was filtered and washed with a mixture of ethanol and distilled water, dried at 70°C for 8 hours, and ground to obtain a cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst.

[0085] (3) Elemental spectroscopy analysis of cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst

[0086] The prepared cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst was analyzed by elemental energy spectrum. Fig. 9 .

[0087] (4) Methanol oxidation performance test of cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst in a three-electrode system

[0088] This step is the same as step (9) in Example 1, and the result is as follows Fig.14 As shown in curve 3.

[0089] Comparative experiment 1

[0090] (1) Preparation of cerium oxide / carbon

[0091] Weigh carbon powder and cerium nitrate hexahydrate in a mass ratio of Vulcan XC-72 carbon powder and cerium nitrate hexahydrate of 1:0.3, disperse the weighed carbon powder and cerium nitrate hexahydrate in 40 ml of distilled water, and stir ultrasonically for 24 hours to obtain a mixed solution A. Weigh 193 mg of sodium hydroxide and dissolve it in 10 ml of distilled water to obtain a sodium hydroxide solution. Add the sodium hydroxide solution dropwise to the mixed solution A to obtain a mixed solution B after the addition is complete. Continue stirring the mixed solution B at room temperature for 12 hours, filter and dry to obtain cerium oxide / carbon.

[0092] (2) Preparation of Cerium Oxide Partially Coated Platinum Nanocubes / Cerium Oxide / Carbon Composite Electrocatalyst

[0093] Weigh 80 mg of the carbon-supported CeO prepared in step (1) 2 Ultrasonic dispersion was performed in 70 ml of N,N-dimethylformamide, and then 40 mg of acetylacetonate platinum was added and stirred at room temperature for 24 hours. The stirred solution was transferred to a high-pressure reactor and reacted at 140°C for 22 hours. After the reactor was naturally cooled to room temperature, the product was filtered and washed with a mixture of ethanol and distilled water, dried at 60°C for 8 hours, and ground to obtain a cerium oxide partially coated platinum nanocube / cerium oxide / carbon composite electrocatalyst.

[0094] (3) Transmission electron microscopy test and particle size statistics of cerium oxide partially coated platinum nanocubes / cerium oxide / carbon composite electrocatalyst

[0095] The prepared cerium oxide partially coated platinum nanocube / cerium oxide / carbon composite electrocatalyst was tested by transmission electron microscopy to obtain the transmission electron microscopy (TEM) image shown in Figure 5a. Figure 5 The particle size of the particles in a is calculated by particle size statistics. Figure 5 Particle size distribution diagram in b.

[0096] (4) High-angle annular dark-field scanning electron microscopy and elemental energy spectrum analysis of the cerium oxide partially coated platinum nanocube / cerium oxide / carbon composite electrocatalyst

[0097] The prepared cerium oxide partially coated platinum nanocube / cerium oxide / carbon composite electrocatalyst was tested by high-angle annular dark-field scanning electron microscopy. Fig.10 a, yes Fig.10 a element spectrum analysis Fig.10 bf.

[0098] (5) X-ray diffraction test of cerium oxide partially coated platinum nanocubes / cerium oxide / carbon composite electrocatalyst

[0099] The prepared cerium oxide partially coated platinum nanocube / cerium oxide / carbon composite electrocatalyst was subjected to an X-ray diffraction (XRD) pattern, such as Fig.11 As shown in the middle curve 3.

[0100] (6) Methanol oxidation performance test of cerium oxide partially coated platinum nanocubes / cerium oxide / carbon composite electrocatalyst in a three-electrode system

[0101] This step is the same as step (9) in Example 1, and the result is as follows Fig.13 As shown in the middle curve 2.

[0102] (7) Test on the CO poisoning resistance of the Cerium Oxide Partially Coated Platinum Nanocube / Cerium Oxide / Carbon Composite Electrocatalyst

[0103] This step is the same as step (10) in Example 1, and the result is as follows Fig.15 As shown in the middle curve 2.

[0104] (8) Stability test of the cerium oxide partially coated platinum nanocube / cerium oxide / carbon composite electrocatalyst

[0105] This step is the same as step (11) in Example 1, and the result is as follows Fig.17 As shown, the scanning circle number of curve A is the 1st circle, and the scanning circle number of curve B is the 600th circle.

[0106] Comparative experiment 2

[0107] (1) The X-ray diffraction test of Pt / C (20% by mass of platinum) commercialized by Johnson-Mathey Company in the UK, such as Fig.11 As shown in the middle curve 4.

[0108] (2) The methanol oxidation performance test of commercial Pt / C (platinum mass percentage 20%) in a three-electrode system by Johnson-Mathey Company of the United Kingdom was carried out in the same manner as step (9) in Example 1. The results are shown in FIG. Fig.13 As shown in the middle curve 3.

[0109] (3) The anti-CO poisoning performance test of the commercial Pt / C (platinum mass percentage 20%) catalyst of Johnson-Mathey, UK was the same as step (10) in Example 1. The results are as follows Fig.15 As shown in the middle curve 3.

[0110] (4) The stability test of the commercial Pt / C (platinum mass percentage 20%) catalyst of Johnson-Mathey, UK was carried out in the same manner as step (11) in Example 1. The results are shown in FIG. Fig.18 As shown, the scanning circle number of curve A is the 1st circle, and the scanning circle number of curve B is the 600th circle.

[0111] Test results of the present invention:

[0112] from Figures 1 to 4 It can be seen that in the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst prepared by the present invention, the catalyst particles do present a cubic morphology and are relatively evenly dispersed, with a particle size of approximately 9 to 12 nm.

[0113] from Figure 5 , Figure 6 It can be seen that the particles in the cerium oxide partially coated platinum nanocubes / cerium oxide / carbon composite electrocatalyst obtained by the preparation method provided in Comparative Experiment 1 do show a cubic morphology and are relatively evenly dispersed, with a particle size of about 12 nm.

[0114] from Figures 7 to 9 It can be seen that in the cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst prepared by the present invention, the copper element is distributed not only in the carrier area, but also inside the area where the platinum nanocubes are located, further proving that the platinum copper alloy phase is indeed generated.

[0115] from Figures 7-10It can be seen that in the cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst prepared by the present invention and the cerium oxide partially coated platinum nanocubes / cerium oxide / carbon composite electrocatalyst obtained by the preparation method provided in Comparative Experiment 1, oxygen and cerium elements are distributed not only in the carrier area, but also around the nanocubes, indicating that the surface of the platinum copper nanocubes is indeed partially coated with the cerium oxide substance.

[0116] from Fig.11 It can be seen that the platinum XRD characteristic peak (curve 1) of the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst prepared by the present invention is shifted to a high angle compared to the platinum XRD characteristic peak in the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst (curve 3) obtained by the preparation method provided in Comparative Experiment 1 and the commercial Pt / C catalyst (curve 4) of Johnson-Matthey Company, indicating that the platinum in the cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst prepared by the present invention has undergone lattice contraction, further proving the formation of the alloy phase. In addition, by comparing curves 1 and 2, it is found that after loading the PtCu cube, the CeO 2 The intensity of the characteristic peak becomes weaker, which is due to the solvothermal reaction between Pt and CeO 2 The redox reaction causes CeO 2 This is caused by the deterioration of crystallinity.

[0117] from Fig.12 It can be seen that the cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst prepared by the present invention has a more obvious EPR signal than the cerium oxide partially coated platinum nanocubes / cerium oxide / carbon composite electrocatalyst (curve 2) obtained by the preparation method provided in Comparative Experiment 1, indicating that the former has a higher content of oxygen vacancy defects.

[0118] from Fig.13 It can be seen that in the methanol oxidation performance test carried out under the same theoretical platinum loading, the methanol oxidation starting potential of the cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst (curve 1) obtained by the preparation method provided in Example 1 is more negative than that of the cerium oxide partially coated platinum nanocubes / cerium oxide / carbon composite electrocatalyst (curve 2) and the Johnson-Matthey commercial Pt / C catalyst (curve 3) obtained by the preparation method provided in Comparative Experiment 1, and the peak current density is higher, indicating that the cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst has a more superior methanol oxidation activity than the cerium oxide partially coated platinum nanocubes / cerium oxide / carbon composite electrocatalyst and the commercial Pt / C catalyst.

[0119] from Fig.14 It can be seen that in the methanol oxidation performance test conducted under the same theoretical platinum loading, the cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalysts prepared by the preparation methods provided in Examples 2 to 4 all showed relatively excellent methanol oxidation activity.

[0120] from Fig.15 It can be seen that the starting potential of the cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst (curve 1) for CO oxidation is significantly negatively shifted compared to the cerium oxide partially coated platinum nanocubes / cerium oxide / carbon composite electrocatalyst (curve 2) obtained by the preparation method provided in Comparative Experiment 1 and the Johnson-Matthey commercial Pt / C catalyst (curve 3), indicating that CO is more easily oxidized and desorbed on the surface of the cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst, that is, the cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst prepared by the present invention has a more excellent ability to resist CO poisoning.

[0121] from Figures 16 to 18 It can be seen that after 600 cycles of cyclic scanning, the peak current density of methanol oxidation of the cerium oxide partially coated platinum copper nanocubes / copper doped cerium oxide / carbon composite electrocatalyst prepared by the present invention decayed by 28% ( Fig.16 ), while the cerium oxide partially coated platinum nanocube / cerium oxide / carbon composite electrocatalyst obtained by the preparation method provided in Comparative Experiment 1 ( Fig.17 ) and Johnson-Mathey commercialized Pt / C catalysts ( Fig.18 )'s methanol oxidation peak current density decayed by 44% and 44%, respectively, indicating that the stability of the cerium oxide partially coated platinum copper nanocubes / copper-doped cerium oxide / carbon composite electrocatalyst prepared in the present invention is significantly improved compared with the commercial Pt / C catalyst and the cerium oxide partially coated platinum nanocubes / cerium oxide / carbon composite electrocatalyst.

Claims

1. A method for preparing a composite electrocatalyst of platinum-copper nanocubes partially coated with cerium oxide, characterized in that: The following steps are involved: a. Preparation of copper-doped cerium oxide / carbon Carbon powder and cerium metal salt are weighed at a mass ratio of Vulcan XC-72 carbon powder and cerium metal salt of 1:0.2-0.4, and copper metal salt is weighed at a molar ratio of cerium metal salt: copper metal salt of 1:0.1-2.0; the weighed carbon powder, cerium metal salt and copper metal salt are dispersed in 40 ml of distilled water, and ultrasonically stirred for 10-30 hours to obtain a mixed solution A; 130-275 mg of sodium hydroxide is weighed and dissolved in 10 ml of distilled water to obtain a sodium hydroxide solution; the sodium hydroxide solution is added dropwise to the above mixed solution A to obtain a mixed solution B after the dropwise addition is completed; the mixed solution B is stirred at room temperature for 10-15 hours, filtered and dried to obtain copper-doped cerium oxide / carbon; b. Preparation of Pt-Cu nanocubes partially coated with Cerium Oxide / Copper-doped Cerium Oxide / Carbon composite electrocatalyst Weigh 80 mg of the carbon-supported Cu prepared in step a 2+ The doped CeO2 is ultrasonically dispersed in 50-100 ml of N,N-dimethylformamide, and then 40-60 mg of platinum precursor is added and stirring is continued at room temperature for 20-30 hours; the stirred solution is transferred to a high-pressure reactor and reacted at 120-150°C for 20-35 hours; after the reactor is naturally cooled to room temperature, the product is filtered and washed with a mixture of ethanol and distilled water, dried at 60-70°C for 8 hours, and ground to obtain a cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst.

2. The method for preparing the cerium oxide partially coated platinum copper nanocube composite electrocatalyst according to claim 1, characterized in that: The cerium metal salt is one of cerium nitrate hexahydrate and cerium chloride; the copper metal salt is one of copper nitrate trihydrate and copper chloride; the platinum precursor is one of platinum acetylacetonate and chloroplatinic acid.

3. The method for preparing the cerium oxide partially coated platinum copper nanocube composite electrocatalyst according to claim 1, characterized in that: The following steps are involved: a. Preparation of copper-doped cerium oxide / carbon Carbon powder and cerium nitrate hexahydrate are weighed at a mass ratio of Vulcan XC-72 carbon powder and cerium nitrate hexahydrate of 1:0.3, and copper nitrate trihydrate is weighed at a molar ratio of cerium nitrate hexahydrate: copper nitrate trihydrate of 1:1; the weighed carbon powder, cerium nitrate hexahydrate and copper nitrate trihydrate are dispersed in 40 ml of distilled water, and ultrasonically stirred for 24 hours to obtain a mixed solution A; 193 mg of sodium hydroxide is weighed and dissolved in 10 ml of distilled water to obtain a sodium hydroxide solution; the sodium hydroxide solution is added dropwise to the above mixed solution A to obtain a mixed solution B after the addition is complete; the mixed solution B is stirred at room temperature for 12 hours, filtered and dried to obtain copper-doped cerium oxide / carbon; b. Preparation of Pt-Cu nanocubes partially coated with Cerium Oxide / Copper-doped Cerium Oxide / Carbon composite electrocatalyst Weigh 80 mg of the carbon-supported Cu prepared in step a 2+ Doped CeO2 was ultrasonically dispersed in 70 ml of N,N-dimethylformamide, and then 40 mg of platinum acetylacetonate was added and stirred at room temperature for 24 hours; the stirred solution was transferred to a high-pressure reactor and reacted at 140°C for 22 hours; after the reactor was naturally cooled to room temperature, the product was filtered and washed with a mixture of ethanol and distilled water, dried at 60°C for 8 hours, and ground to obtain a cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst.

4. The method for preparing the cerium oxide partially coated platinum copper nanocube composite electrocatalyst according to claim 1, characterized in that: The following steps are involved: a. Preparation of copper-doped cerium oxide / carbon Carbon powder and cerium nitrate hexahydrate are weighed at a mass ratio of Vulcan XC-72 carbon powder and cerium nitrate hexahydrate of 1:0.2, and copper nitrate trihydrate is weighed at a molar ratio of cerium nitrate hexahydrate to copper nitrate trihydrate of 1:0.2; the weighed carbon powder, cerium nitrate hexahydrate and copper nitrate trihydrate are dispersed in 40 ml of distilled water, and ultrasonically stirred for 24 hours to obtain a mixed solution A; 130 mg of sodium hydroxide is weighed and dissolved in 10 ml of distilled water to obtain a sodium hydroxide solution; the sodium hydroxide solution is added dropwise to the above mixed solution A to obtain a mixed solution B after the addition is complete; the mixed solution B is stirred at room temperature for 12 hours, filtered and dried to obtain copper-doped cerium oxide / carbon; b. Preparation of Pt-Cu nanocubes partially coated with Cerium Oxide / Copper-doped Cerium Oxide / Carbon composite electrocatalyst Weigh 80 mg of the carbon-supported Cu prepared in step a 2+ Doped CeO2 was ultrasonically dispersed in 70 ml of N,N-dimethylformamide, and then 40 mg of platinum acetylacetonate was added and stirred at room temperature for 24 hours; the stirred solution was transferred to a high-pressure reactor and reacted at 120°C for 20 hours; after the reactor was naturally cooled to room temperature, the product was filtered and washed with a mixture of ethanol and distilled water, dried at 60°C for 8 hours, and ground to obtain a cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst.

5. The method for preparing the cerium oxide partially coated platinum copper nanocube composite electrocatalyst according to claim 1, characterized in that: The following steps are involved: a. Preparation of copper-doped cerium oxide / carbon Carbon powder and cerium nitrate hexahydrate are weighed at a mass ratio of Vulcan XC-72 carbon powder and cerium nitrate hexahydrate of 1:0.3, and copper nitrate trihydrate is weighed at a molar ratio of cerium nitrate hexahydrate: copper nitrate trihydrate of 1:0.4; the weighed carbon powder, cerium nitrate hexahydrate and copper nitrate trihydrate are dispersed in 40 ml of distilled water, and ultrasonically stirred for 24 hours to obtain a mixed solution A; 193 mg of sodium hydroxide is weighed and dissolved in 10 ml of distilled water to obtain a sodium hydroxide solution; the sodium hydroxide solution is added dropwise to the above mixed solution A to obtain a mixed solution B after the addition is complete; the mixed solution B is stirred at room temperature for 12 hours, filtered and dried to obtain copper-doped cerium oxide / carbon; b. Preparation of Pt-Cu nanocubes partially coated with Cerium Oxide / Copper-doped Cerium Oxide / Carbon composite electrocatalyst Weigh 80 mg of the carbon-supported Cu prepared in step a 2+ Doped CeO2 was ultrasonically dispersed in 70 ml of N,N-dimethylformamide, and then 40 mg of platinum acetylacetonate was added and stirred at room temperature for 24 hours; the stirred solution was transferred to a high-pressure reactor and reacted at 140°C for 22 hours; after the reactor was naturally cooled to room temperature, the product was filtered and washed with a mixture of ethanol and distilled water, dried at 60°C for 8 hours, and ground to obtain a cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst.

6. The method for preparing the cerium oxide partially coated platinum copper nanocube composite electrocatalyst according to claim 1, characterized in that: The following steps are involved: a. Preparation of copper-doped cerium oxide / carbon Carbon powder and cerium chloride were weighed at a mass ratio of Vulcan XC-72 carbon powder and cerium nitrate hexahydrate of 1:0.4, and copper chloride was weighed at a molar ratio of cerium chloride:copper chloride of 1:1.5; the weighed carbon powder, cerium chloride and copper chloride were dispersed in 40 ml of distilled water, and ultrasonically stirred for 3 hours to obtain a mixed solution A; 275 mg of sodium hydroxide was weighed and dissolved in 10 ml of distilled water to obtain a sodium hydroxide solution; the sodium hydroxide solution was added dropwise to the mixed solution A to obtain a mixed solution B after the addition was complete; the mixed solution B was stirred at room temperature for 15 hours, filtered and dried to obtain copper-doped cerium oxide / carbon; b. Preparation of Pt-Cu nanocubes partially coated with Cerium Oxide / Copper-doped Cerium Oxide / Carbon composite electrocatalyst Weigh 80 mg of the carbon-supported Cu prepared in step a 2+ Doped CeO2 was ultrasonically dispersed in 100 ml N,N-dimethylformamide, and then 60 mg chloroplatinic acid was added and stirring was continued at room temperature for 30 hours; the stirred solution was transferred to a high-pressure reactor and reacted at 150°C for 20 hours; after the reactor was naturally cooled to room temperature, the product was filtered and washed with a mixture of ethanol and distilled water, dried at 70°C for 8 hours, and ground to obtain a cerium oxide partially coated platinum copper nanocube / copper doped cerium oxide / carbon composite electrocatalyst.

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