Lead-modulated high-poisoning-resistance intermetallic compound bifunctional catalyst as well as preparation method and application thereof

Abstract

The invention provides a lead-modulated high-poisoning-resistance intermetallic compound bifunctional catalyst as well as a preparation method and application thereof, and belongs to the technical field of energy materials. According to the catalyst, a carbon substrate is used as a carrier to load quaternary intermetallic compound nanoparticles composed of platinum, cobalt, copper and lead according to the molar ratio of Pt: Co: Cu: Pb being 4: (1.75-2.5): (1.75-2.5): (0.05-0.5), and the loading capacity of platinum is 20-70 wt%; the particle size of the quaternary intermetallic compound nanoparticles is 3-6 nm; the catalyst is prepared by wet chemical impregnation, heat treatment in a reducing atmosphere and acid pickling, and is used for oxygen reduction reaction catalysis of a cathode in a hydrogen fuel cell and / or methanol oxidation reaction catalysis of an anode in a direct methanol fuel cell; the half-wave potential of the catalyst in ORR is 25 mV or above higher than that of a commercial Pt / C catalyst, and the methanol oxidation peak current density in MOR is 2.5-5 times that of the commercial Pt / C catalyst or a commercial PtRu / C catalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of energy materials, and particularly relates to a lead-modulated highly anti-poisoning intermetallic compound bifunctional catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Platinum-based catalysts have excellent catalytic activity, stability, and electrical conductivity, and are widely used in fuel cells. However, there is still room for improvement in traditional platinum-based catalysts: firstly, the loading of precious metal platinum is often relatively high (>0.2 mg / cm 2 ), resulting in increased costs; secondly, in acidic / alkaline working conditions, the transition metal components of traditional platinum catalysts exhibit dissolution phenomena, leading to a sharp decline in the stability of the catalysts (usually <10,000 cycles); thirdly, traditional platinum-based catalysts cannot simultaneously achieve high ORR selectivity and anti-methanol poisoning characteristics, resulting in cross-interference problems between cathode ORR and anode MOR in methanol fuel cells. Therefore, the research and development of new and efficient bifunctional catalysts that are simultaneously applicable to the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) has become an important direction for breaking through the bottleneck of energy conversion efficiency, such as platinum-based multi-element alloy systems.

[0003] In the prior art, the Chinese patent application with the publication number CN113937311B provides a preparation method of a platinum-copper-nickel catalyst supported on a two-dimensional porous silica non-carbon carrier. The copper-nickel hydroxide nanosheets are prepared by a chemical reduction method and a replacement method as a template and are simultaneously introduced as the second and third metals to promote the catalytic performance of the platinum catalyst. Then, silica is coated on the surface of the copper-nickel compound, and after reduction treatment, it becomes a copper-nickel alloy and is uniformly and tightly loaded on the surface of the silica nanosheets. Next, platinum is loaded by replacement to form a platinum-copper-nickel alloy, and finally, pickling is carried out to obtain a platinum-copper-nickel catalyst supported on a two-dimensional porous silica non-carbon carrier. Compared with traditional commercial platinum-carbon catalysts, this catalyst has more excellent MOR electrocatalytic performance, and binary / ternary alloys such as Pt-Co and Pt-Cu-Ni can improve the ORR activity through the lattice strain effect. However, due to the existence of a disordered solid solution structure, the transition metals in the catalyst are prone to rapid loss during potential cycling.

[0004] The Chinese patent application with the publication number CN117317267 provides a preparation method of a PtM alloy catalyst supported on a cerium dioxide / carbon composite support. A cerium dioxide / carbon composite support with a controllable CeO2 loading and uniform dispersion is prepared through an alkaline hydrothermal reaction. Then, a Pt precursor and a transition metal M precursor are loaded onto the cerium dioxide / carbon composite support and calcined in a protective-reducing mixed gas to prepare a PtM alloy catalyst supported on the cerium dioxide / carbon composite support, PtM-CeO2 / C. M is a transition metal Ni, Co, Cu, or Fe. This catalyst can be used for the electrochemical catalysis of ORR and MOR. However, the introduction of oxides often comes at the cost of stability. For example, the selective dissolution of cerium dioxide at anodic potentials will expose the platinum lattice and accelerate the deactivation of the catalyst. That is, the traditional alloying strategy is difficult to balance the contradictory requirements of ORR (requiring weak adsorption characteristics) and MOR (requiring strong adsorption characteristics) for the surface electronic structure.

[0005] In view of this, it is necessary to design a lead-modulated highly anti-poisoning intermetallic bifunctional catalyst, its preparation method and application to solve the above technical problems. Summary of the Invention

[0006] In view of the technical problems existing in the background art, this application provides a lead-modulated highly anti-poisoning intermetallic bifunctional catalyst, its preparation method and application to solve the technical problems of high cost of traditional platinum-based catalysts, easy dissolution of transition metals under acidic / alkaline conditions, and difficulty in being simultaneously applicable to ORR and MOR. The half-wave potential of the lead-modulated highly anti-poisoning intermetallic bifunctional catalyst provided by this application is 25 mV higher than that of a commercial Pt / C catalyst, and the peak current density of methanol oxidation is 2.5 - 5 times that of a commercial Pt / C catalyst or a commercial PtRu / C catalyst.

[0007] In the first aspect, an embodiment of this application provides a lead-modulated highly anti-poisoning intermetallic bifunctional catalyst. The bifunctional catalyst is a carbon matrix-supported quaternary intermetallic nanoparticle composed of platinum, cobalt, copper, and lead. Among them, the molar ratio of platinum, cobalt, copper, and lead is Pt:Co:Cu:Pb = 4:(1.75 - 2.5):(1.75 - 2.5):(0.05 - 0.5), and the loading amount of platinum is 20 - 70 wt%. The particle size of the quaternary intermetallic nanoparticle is 3 - 6 nm. The bifunctional catalyst is prepared by wet chemical impregnation, heat treatment in a reducing atmosphere, and pickling.

[0008] In the second aspect, an embodiment of this application provides a preparation method of a lead-modulated highly anti-poisoning intermetallic bifunctional catalyst, including the following steps: S1. Ultrasonically disperse the nano-carbon support evenly in a solvent to obtain a mixed solution. Then add platinum salt, cobalt salt, copper salt, and lead salt to the mixed solution, and ultrasonically disperse and stir again to obtain a suspension. S2. Dry the suspension obtained in step S1 using a rotary evaporator to obtain black powder A. S3. Grind the black powder A obtained in step S2 and place it in a tube furnace. Anneal it in a reducing atmosphere to obtain black powder B. S4. Disperse the black powder B obtained in step S3 in an acid solution, stir for a period of time, then perform suction filtration, wash with deionized water, and dry to obtain a lead-modulated high anti-poisoning intermetallic compound bifunctional catalyst.

[0009] Further, in step S1, the molar ratio of metal atoms in the platinum salt, cobalt salt, copper salt, and lead salt is Pt:Co:Cu:Pb = 4:(1.75 - 2.5):(1.75 - 2.5):(0.05 - 0.5).

[0010] Further, in step S1, the nano-carbon support is graphitized carbon black (GCB), KJ600, KJ300, or BP2000; the solvent is deionized water, isopropanol, ethylene glycol, or ethanol; the platinum salt is platinum acetylacetonate, chloroplatinic acid, or potassium chloroplatinate, the copper salt is copper chloride, cuprous chloride, or copper acetylacetonate, the cobalt salt is cobalt chloride, cobaltous chloride, or cobalt acetylacetonate, and the lead salt is lead chloride, lead acetate, or lead acetylacetonate.

[0011] Further, in step S1, the ultrasonic time is 15 - 30 min, and the stirring time is greater than or equal to 6 h.

[0012] Further, in step S2, the rotary evaporation temperature is 60 - 80 °C, and the rotary evaporation time is 0.25 - 2 h.

[0013] Further, in step S3, the reducing atmosphere is hydrogen, hydrogen-argon mixture, or ammonia; the annealing temperature is 800 - 1000 °C, the annealing time is 0.5 - 3 h, and the heating rate during annealing is 2 - 10 °C / min.

[0014] Further, in step S4, the acid solution is one or a mixture of sulfuric acid, hydrochloric acid, perchloric acid, and nitric acid, and the concentration of the acid is 0.1 - 1 mol / L.

[0015] Further, the temperature for stirring treatment with the acid solution is 60 - 80 °C, and the time for stirring treatment with the acid solution is 0.25 - 4 h.

[0016] In a third aspect, an embodiment of the present application provides an application of a lead-modulated highly anti-poisoning intermetallic compound bifunctional catalyst, and the lead-modulated highly anti-poisoning intermetallic compound bifunctional catalyst is used for catalyzing the oxygen reduction reaction at the cathode in a hydrogen fuel cell and / or catalyzing the methanol oxidation reaction at the anode in a direct methanol fuel cell.

[0017] The beneficial effects of the present application are as follows: The present application provides a lead-modulated highly anti-poisoning intermetallic compound bifunctional catalyst, a preparation method thereof, and an application thereof. Quaternary intermetallic compound nanoparticles composed of platinum, cobalt, copper, and lead are supported on a carbon matrix as a carrier, and the obtained bifunctional catalyst is used for catalyzing the oxygen reduction reaction at the cathode in a hydrogen fuel cell and / or catalyzing the methanol oxidation reaction at the anode in a direct methanol fuel cell.

[0018] (1) In the present application, copper and lead are introduced to adjust the d-band center position of platinum (Pt) through ligand effect and charge transfer, so as to weaken the binding strength between platinum and oxygen adsorption species (such as OH, OOH), and improve the ORR catalytic activity. Secondly, copper and lead with large differences in atomic radius from platinum and cobalt will also cause lattice distortion, thereby optimizing the geometric arrangement of platinum atoms, enabling more platinum atoms to participate in the oxygen reduction reaction. The combined action of copper, lead, platinum, and cobalt can form more effective active sites, enhancing the ORR activity and selectivity. In addition, copper promotes the cleavage of the O-O bond by forming Cu-O bonds, which can effectively reduce the energy barrier of the ORR rate-determining step (O2→OOH). Lead inhibits the occurrence of side reactions (such as the generation of H2O2, which can cause radical corrosion of the membrane electrode), improves the reaction selectivity, and reduces cobalt dissolution and platinum agglomeration at the same time. The cooperation of copper and lead effectively improves the ORR activity and stability of the catalyst.

[0019] (2) In the present application, cobalt, copper, and lead are introduced to jointly regulate the electronic structure of platinum and lower the d-band center position of platinum. Among them, there is a strong hybridization effect between the 6p orbit of lead and the 5p orbit of platinum, which is beneficial to maintaining the d-band center of platinum in the optimal region suitable for MOR catalysis and enhancing the catalytic activity. In addition, on the one hand, copper and its oxides can dissociate water molecules on the surface of the catalyst at a lower potential, generating more hydroxyl groups, which can combine with CO intermediates to form intermediate species such as COOH, promoting the oxidation and removal of CO, thereby improving the efficiency of the methanol oxidation reaction. On the other hand, the introduction of Pb forms a selective catalytic interface, changing the methanol oxidation path from being dominated by CO ads to being dominated by HCOO - in an alkaline medium, improving the CO tolerance and enhancing the anti-poisoning ability of MOR.

[0020] In the present application, by constructing a quaternary cooperative and long-range ordered intermetallic crystal framework of platinum, cobalt, copper, and lead, the d-band electronic structure of platinum is regulated at the atomic scale, and the methanol oxidation path is changed from being dominated by CO in an alkaline mediumads The dominant species is transformed into HCOO - as the dominant species, enhancing CO tolerance, and enabling the obtained bifunctional catalyst to exhibit high catalytic activity and high stability in both ORR and MOR. The half-wave potential in ORR is 28 mV higher than that of commercial Pt / C catalyst, and the peak current density of methanol oxidation in MOR is 4.26 times that of commercial Pt / C catalyst and 2.68 times that of commercial PtRu / C catalyst, which is of great significance for promoting the large-scale commercial application of fuel cells.

[0021] The above description is only an overview of the technical solution of this application. In order to understand the technical means of this application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of this application more obvious and understandable, the specific embodiments of this application are specifically exemplified below. Brief Description of the Drawings

[0022] In order to illustrate the technical solution of this application more clearly, the drawings used in this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 XRD pattern of the lead-modulated highly CO-tolerant intermetallic compound bifunctional catalyst provided in Example 1 of this application; Figure 2 SEM image (a) and EDS mapping test images (b - e) of the lead-modulated highly CO-tolerant intermetallic compound bifunctional catalyst provided in Example 1 of this application; Figure 3 TEM image of the lead-modulated highly CO-tolerant intermetallic compound bifunctional catalyst provided in Example 1 of this application; Figure 4 Comparison diagram of rotating disk polarization curves (after i-R compensation) of commercial Pt / C catalyst, the catalyst provided in Example 1 and Comparative Examples 1 - 2 of this application in acidic medium; Figure 5 Comparison diagram of cyclic voltammograms of MOR of commercial Pt / C catalyst, commercial PtRu / C catalyst and the catalyst provided in Example 1 of this application. Detailed Description of the Embodiments

[0024] The embodiments of the technical solution of this application will be described in detail below with reference to the drawings. The following embodiments are only used to illustrate the technical solution of this application more clearly, so they are only examples and cannot be used to limit the protection scope of this application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0026] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "a plurality" is more than two unless otherwise specifically defined.

[0027] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments may be included in at least one embodiment of this application. The phrase does not necessarily refer to the same embodiment at each occurrence in the specification, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0028] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after. For those of ordinary skill in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0029] There is still room for improvement in traditional platinum-based catalysts as follows: First, the loading of the precious metal platinum is often relatively high (>0.2 mg / cm 2 ), resulting in increased costs; second, in acidic / alkaline working conditions, the transition metal components of traditional platinum catalysts exhibit leaching phenomena, leading to a sharp decline in the stability of the catalysts (usually <10,000 cycles); third, traditional platinum-based catalysts cannot simultaneously achieve high ORR selectivity and anti-methanol poisoning characteristics, resulting in cross-interference problems between cathode ORR and anode MOR in methanol fuel cells.

[0030] To solve the above technical problems, the present application provides a lead-modulated highly anti-poisoning intermetallic bifunctional catalyst, a preparation method thereof, and an application thereof. Among them, by introducing cobalt, copper, and lead, the loading amount of precious metal platinum is reduced, and the catalyst preparation cost is reduced; by introducing cobalt, copper, and lead, the d-band center position of platinum is adjusted. There is a strong hybridization effect between the 6p orbit of lead and the 5p orbit of platinum, which is beneficial to maintaining the d-band center of platinum in the optimal region suitable for MOR catalysis and improving the catalytic activity; copper and lead cooperate to simultaneously improve the ORR activity and MOR anti-poisoning ability.

[0031] In the first aspect, an embodiment of the present application provides a lead-modulated highly anti-poisoning intermetallic bifunctional catalyst. The catalyst is a carbon matrix-supported quaternary intermetallic nanoparticle composed of platinum, cobalt, copper, and lead. Among them, the molar ratio of platinum, cobalt, copper, and lead is Pt:Co:Cu:Pb = 4:(1.75 - 2.5):(1.75 - 2.5):(0.05 - 0.5), the loading amount of platinum is 20 - 70 wt%, and the particle size of the quaternary intermetallic nanoparticle is 3 - 6 nm. The catalyst is prepared by wet chemical impregnation, heat treatment in a reducing atmosphere, and pickling, and is used for catalyzing the oxygen reduction reaction at the cathode in a hydrogen fuel cell and / or catalyzing the methanol oxidation reaction at the anode in a direct methanol fuel cell.

[0032] The present application constructs a platinum-based quaternary intermetallic catalyst system, and uses the synergistic effect of the d-electron orbital hybridization effect and the lattice strain effect between platinum and Cu-Co-Pb transition metals to optimize the electronic structure of platinum, and simultaneously improve the intrinsic ORR activity and methanol anti-poisoning ability of the catalyst. On the one hand, the present application uses the strong hybridization effect between the 6p orbit of lead and the 5p orbit of platinum to regulate the d-band electronic structure of platinum, which is beneficial to maintaining the d-band center of platinum in the optimal region suitable for MOR catalysis and improving the catalytic activity. On the other hand, the introduction of Pb forms a selective catalytic interface, which changes the methanol oxidation path from CO ads dominant to HCOO - dominant in an alkaline medium, improves the CO tolerance, and simultaneously improves the ORR selectivity and MOR anti-poisoning ability.

[0033] In the second aspect, an embodiment of the present application provides a preparation method of a lead-modulated highly anti-poisoning intermetallic bifunctional catalyst, including the following steps: S1, ultrasonically disperse the nano-carbon carrier evenly in a solvent to obtain a mixed solution, and then add platinum salt, cobalt salt, copper salt, and lead salt to the mixed solution, and ultrasonically disperse and stir again to obtain a suspension.

[0034] In the embodiment of the present application, the nano-carbon carrier is graphitized carbon black (GCB), KJ600, KJ300, or BP2000. The solvent is deionized water, isopropanol, ethylene glycol, or ethanol.

[0035] In the embodiments of the present application, the molar ratio of metal atoms in the platinum salt, cobalt salt, copper salt, and lead salt is Pt:Co:Cu:Pb = 4:(1.75 - 2.5):(1.75 - 2.5):(0.05 - 0.5). Among them, the platinum salt is platinum acetylacetonate, chloroplatinic acid, or potassium chloroplatinate; the copper salt is copper chloride, cuprous chloride, or copper acetylacetonate; the cobalt salt is cobalt chloride, cobaltous chloride, or cobalt acetylacetonate; and the lead salt is lead chloride, lead acetate, or lead acetylacetonate.

[0036] In the embodiments of the present application, the ultrasonic time in step S1 is 15 - 30 min, and the stirring time is greater than or equal to 6 h, preferably 6 - 24 h.

[0037] S2. Dry the suspension obtained in step S1 with a rotary evaporator to obtain black powder A.

[0038] In the embodiments of the present application, the temperature of rotary evaporation is 60 - 80 °C, and the time is 0.25 - 2 h.

[0039] S3. Grind the black powder A obtained in step S2 and put it into a tubular furnace, and anneal it in a reducing atmosphere to obtain black powder B.

[0040] In the embodiments of the present application, the reducing atmosphere is hydrogen, hydrogen-argon mixture, or ammonia.

[0041] In the embodiments of the present application, the annealing temperature is 800 - 1000 °C, and the annealing time is 0.5 - 3 h. The heating rate during the annealing process is 2 - 10 °C / min.

[0042] S4. Disperse the black powder B obtained in step S3 in an acid solution, stir for a period of time, then filter by suction, wash with deionized water, and dry to obtain a lead-modulated highly anti-poisoning intermetallic compound bifunctional catalyst.

[0043] In the embodiments of the present application, the acid solution is one or a mixture of sulfuric acid, hydrochloric acid, perchloric acid, and nitric acid, and the concentration of the acid is 0.1 - 1 mol / L. The amount of the acid solution used is sufficient to submerge the black powder B.

[0044] In the embodiments of the present application, the temperature for stirring treatment with the acid solution is 60 - 80 °C, and the time for stirring treatment with the acid solution is 0.25 - 4 h.

[0045] In a third aspect, the embodiments of the present application provide an application of a lead-modulated highly anti-poisoning intermetallic compound bifunctional catalyst. The lead-modulated highly anti-poisoning intermetallic compound bifunctional catalyst is used for catalyzing the oxygen reduction reaction at the cathode in a hydrogen fuel cell and / or catalyzing the methanol oxidation reaction at the anode in a direct methanol fuel cell.

[0046] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. For those without specific technologies or conditions indicated in the embodiments, the technologies or conditions described in the literature in the art or according to the product specifications are followed. For the reagents or instruments without the manufacturer indicated, they are all conventional products that can be obtained through commercial purchase.

[0047] The commercial Pt / C catalyst used in the embodiments of the present application is HISPEC9100, JM 60% platinum-carbon catalyst; the commercial PtRu / C catalyst used in the embodiments of the present application is TEC61E54-HT2 (total loading of Pt and Ru is 54 wt%).

[0048] Example 1 Example 1 provides a lead-modulated highly anti-poisoning intermetallic bifunctional catalyst, including carbon-supported platinum-cobalt-copper-lead quaternary intermetallic nanoparticles, wherein the molar ratio of platinum, cobalt, copper, and lead is Pt:Co:Cu:Pb = 16.40:9.95:9.85:1, and the loading of platinum is 49.59 wt%. The preparation steps of the catalyst are as follows: S1. Add 40 mg of carbon black (KJ600) to 40 mL of ethanol, and ultrasonically treat for 30 min to uniformly disperse the carbon black to obtain a mixed solution. Then add 40 mg of platinum acetylacetonate, 16 mg of cobalt acetylacetonate, 16 mg of copper acetylacetonate, and 2 mg of lead acetate to the mixed solution, and ultrasonically treat again for 30 min for sufficient dispersion, and stir at 400 rpm for 24 h to obtain a suspension.

[0049] S2. Heat the suspension obtained in step S1 to 80 °C with a rotary evaporator and dry for 30 min to obtain black powder A.

[0050] S3. Grind the black powder A obtained in step S2 and put it into a tube furnace, and heat it to 800 °C at a rate of 5 °C / min in a hydrogen-argon mixed atmosphere for annealing, keep it warm for 2 h, and cool it naturally to obtain black powder B.

[0051] S4. Disperse the black powder B obtained in step S3 in 0.1 mol / L perchloric acid solution, stir at a rotation speed of 400 rpm at 60 °C for 4 h, then filter by suction, wash with deionized water, and dry to obtain a lead-modulated highly anti-poisoning intermetallic bifunctional catalyst.

[0052] The X-ray diffraction (XRD) pattern of the catalyst provided in Example 1 is shown in Figure 1As shown in the comparison with the standard card (PDF#43-1358) of the Pt compound, the XRD pattern of Example 1 showed the characteristic (110) and (001) superlattice peaks unique to intermetallic compounds near 23° and 33°, indicating the formation of a long-range ordered atomic arrangement structure.

[0053] See the scanning electron microscope image (SEM) of the catalyst provided in Example 1 Figure 2 As shown, it can be seen that the nanoparticles did not agglomerate. Further, EDS mapping was used to analyze the spatial distribution of the sample elements, and the signals of four metal elements, platinum, cobalt, copper, and lead, were successfully observed and evenly distributed in space, indicating that all five elements participated in the alloying.

[0054] See the transmission electron microscope image (TEM) of the catalyst provided in Example 1 Figure 3 As shown. It can be seen that the dark-colored intermetallic compounds are evenly distributed on the carbon support without agglomeration. After measurement, the particle size of the intermetallic compound nanoparticles is between 3 - 6 nm.

[0055] Comparative Example 1 Comparative Example 1 provided a carbon-supported platinum-cobalt-copper intermetallic compound catalyst, including carbon-supported platinum-cobalt-copper intermetallic compound nanoparticles, wherein the molar ratio of platinum, cobalt, and copper was Pt:Co:Cu = 16.40:9.95:9.85, and the platinum loading was 49.59 wt%. Others were the same as in Example 1 and will not be elaborated here.

[0056] Comparative Example 2 Comparative Example 2 provided a carbon-supported platinum-cobalt intermetallic compound catalyst, including carbon-supported platinum-cobalt intermetallic compound nanoparticles, wherein the molar ratio of platinum and cobalt was Pt:Co = 16.40:9.95, and the platinum loading was 49.59 wt%. Others were the same as in Example 1 and will not be elaborated here.

[0057] The rotating disk polarization curves of the commercial Pt / C catalyst, the catalyst provided in Example 1, and Comparative Examples 1 - 2 were tested in an acidic medium. Among them, the electrolyte solution was 0.1 mol / L HClO4 saturated with O2, the scanning rate was 10 mV / s, the scanning voltage range was -0.25 V to 0.8 V, and the rotation speed was 1600 rpm.

[0058] Table 1. Half-wave potential of the catalysts Please refer to Figure 4 and as shown in Table 1, Figure 4Figure 0 is a comparative diagram of the polarization curves of a rotating disk after i-R compensation. Table 1 shows the half-wave potentials of the catalysts obtained from the tests. It can be seen that the half-wave potential of the catalyst in Example 1 exceeds that of the commercial Pt / C catalyst by 28 mV, exceeds the catalyst in Comparative Example 1 by 35 mV, and exceeds the catalyst in Comparative Example 2 by 19 mV. This shows that the oxygen reduction activity of the catalyst of the present application is effectively improved by simultaneously introducing cobalt, copper, and lead.

[0059] In the present application, copper and lead are introduced to adjust the d-band center position of platinum (Pt) through ligand effects and charge transfer, so as to weaken the binding strength between platinum and oxygen adsorption species (such as OH, OOH), and improve the ORR catalytic activity. Secondly, copper and lead, whose atomic radii are quite different from those of platinum and cobalt, will also cause lattice distortion, thereby optimizing the geometric arrangement of platinum atoms and enabling more platinum atoms to participate in the oxygen reduction reaction. In addition, copper promotes the cleavage of the O-O bond by forming Cu-O bonds, which can effectively reduce the energy barrier of the rate-determining step of ORR (O2→OOH). Lead inhibits the occurrence of side reactions (such as the generation of H2O2, which can cause radical corrosion of the membrane electrode), improves the reaction selectivity, and reduces the dissolution of cobalt and the agglomeration of platinum at the same time. Copper and lead cooperate to effectively improve the oxygen reduction activity and stability of the catalyst. Removing lead or removing copper and lead will both lead to blocked reaction paths or increased by-products, weakening the activity and stability of the catalyst; after removing copper, platinum-cobalt-lead cannot form a stable compound.

[0060] Cyclic voltammetry (CV) was used to perform cyclic voltammetry tests on the methanol electrocatalytic oxidation (MOR) of commercial Pt / C catalysts, commercial PtRu / C catalysts, the catalyst provided in Example 1, and Comparative Examples 1-2. Before the test, N2 was introduced for half an hour to saturate the N2 in the electrolyte to exclude the interference of soluble oxygen on the test results. Then, at 25 °C, the sweep rate was set to 50 mV / s, the initial potential was set to 0.1 V, and the scanning voltage range was 0.1 V - 1.0 V (vs. RHE). Twenty cycles of cyclic voltammetry tests were carried out, and the CV curve obtained after stabilization was used as the basis for evaluating the MOR activity of the catalyst. The electrolyte was 1.0 mol / L KOH + 1.0 mol / L CH3OH.

[0061] Table 2. Methanol oxidation peak current density of the catalyst Please refer to Figure 5 and Table 2, Figure 5It is a comparison chart of cyclic voltammetry curves for methanol electrocatalytic oxidation (MOR). Table 2 shows the methanol oxidation peak current density of the tested catalysts. The methanol oxidation peak current density of the catalyst provided in Example 1 in MOR is significantly higher than that of Comparative Examples 1-2, and is 4.26 times that of the commercial Pt / C catalyst and 2.68 times that of the commercial PtRu / C catalyst. It shows that the present application effectively improves the MOR activity of the catalyst by introducing cobalt, copper, and lead simultaneously.

[0062] The present application introduces cobalt, copper, and lead, and uses cobalt, copper, and lead to jointly regulate the electronic structure of platinum, reducing the position of the d-band center of platinum. Among them, there is a strong hybridization effect between the 6p orbit of lead and the 5p orbit of platinum, which is beneficial to maintaining the d-band center of platinum in the optimal region suitable for MOR catalysis and improving the catalytic activity. In addition, on the one hand, copper and its oxides can dissociate water molecules on the surface of the catalyst at a lower potential, generating more hydroxyl groups. These hydroxyl groups can combine with CO intermediates to form intermediate species such as COOH, promoting the oxidation and removal of CO, thereby improving the efficiency of the methanol oxidation reaction. On the other hand, the introduction of Pb forms a selective catalytic interface, which changes the methanol oxidation path from being CO ads dominant to HCOO - dominant in alkaline media, improving the CO tolerance and enhancing the anti-poisoning ability of MOR. However, Comparative Examples 1-2 only use platinum-cobalt or platinum-cobalt-copper combinations. Not only do the aforementioned effects disappear, but it also causes Pt-Co nanoparticles to be more prone to unfavorable structural evolution (such as agglomeration and dissolution) under reaction conditions, reducing the electrochemically active area of the catalyst and weakening the stability.

[0063] In summary, the present application provides a lead-modulated highly anti-poisoning intermetallic bifunctional catalyst, its preparation method and application. A quaternary intermetallic nanoparticle composed of platinum, cobalt, copper, and lead is loaded on a carbon matrix as a carrier. The obtained bifunctional catalyst is used for the oxygen reduction reaction catalysis at the cathode in a hydrogen fuel cell and / or the methanol oxidation reaction catalysis at the anode in a direct methanol fuel cell, showing high catalytic activity and high stability in ORR and MOR. The half-wave potential of this bifunctional catalyst in ORR is 28 mV higher than that of the commercial Pt / C catalyst, and the methanol oxidation peak current density in MOR is 4.26 times that of the commercial Pt / C catalyst and 2.68 times that of the commercial PtRu / C catalyst.

[0064] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples. Embodiments with the same constitution and the same effect as the technical idea within the scope of the technical solution of the present application are included in the technical scope of the present application. In addition, within the scope of not departing from the main idea of the present application, various deformations that those skilled in the art can think of applied to the embodiments and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of the present application.

Claims

1. A lead-modulated highly poison-resistant intermetallic bifunctional catalyst, characterized in that, The bifunctional catalyst uses a carbon matrix as a carrier to support quaternary intermetallic compound nanoparticles composed of platinum, cobalt, copper, and lead; wherein, the molar ratio of platinum, cobalt, copper, and lead is Pt:Co:Cu:Pb = 4:(1.75 - 2.5):(1.75 - 2.5):(0.05 - 0.5), and the loading amount of platinum is 20 - 70 wt%; the particle size of the quaternary intermetallic compound nanoparticles is 3 - 6 nm; the bifunctional catalyst is prepared by wet chemical impregnation, heat treatment in a reducing atmosphere, and pickling.

2. A method for preparing a lead-modulated highly poisoning-resistant intermetallic compound bifunctional catalyst according to claim 1, characterized in that, It includes the following steps: S1, ultrasonically disperse the nano-carbon carrier evenly in a solvent to obtain a mixed solution, then add platinum salt, cobalt salt, copper salt, and lead salt to the mixed solution, ultrasonically disperse again, and stir to obtain a suspension; S2, dry the suspension obtained in step S1 with a rotary evaporator to obtain black powder A; S3, grind the black powder A obtained in step S2 and put it into a tube furnace, anneal in a reducing atmosphere to obtain black powder B; S4, disperse the black powder B obtained in step S3 in an acid solution, stir for a period of time, filter by suction, wash with deionized water, and dry to obtain a lead-modulated highly anti-poisoning intermetallic compound bifunctional catalyst.

3. The preparation method of the lead-modulated highly poison-resistant intermetallic compound bifunctional catalyst according to claim 2, characterized in that, In step S1, the molar ratio of metal atoms in the platinum salt, cobalt salt, copper salt, and lead salt is Pt:Co:Cu:Pb = 4:(1.75 - 2.5):(1.75 - 2.5):(0.05 - 0.5).

4. The preparation method of the lead-modulated highly poison-resistant intermetallic compound bifunctional catalyst according to claim 2, characterized in that, In step S1, the nano-carbon carrier is graphitized carbon black, KJ600, KJ300, or BP2000; the solvent is deionized water, isopropanol, ethylene glycol, or ethanol; the platinum salt is platinum acetylacetonate, chloroplatinic acid, or potassium chloroplatinate, the copper salt is copper chloride, cuprous chloride, or copper acetylacetonate, the cobalt salt is cobalt chloride, cobaltous chloride, or cobalt acetylacetonate, and the lead salt is lead chloride, lead acetate, or lead acetylacetonate.

5. The preparation method of the lead-modulated highly poisoning-resistant intermetallic compound bifunctional catalyst according to claim 2, characterized in that, In step S1, the ultrasonic time is 15 - 30 min, and the stirring time is greater than or equal to 6 h.

6. The preparation method of the lead-modulated highly poisoning-resistant intermetallic compound bifunctional catalyst according to claim 2, wherein, In step S2, the rotary evaporation temperature is 60 - 80 °C, and the rotary evaporation time is 0.25 - 2 h.

7. The preparation method of the lead-modulated highly poison-resistant intermetallic compound bifunctional catalyst according to claim 2, characterized in that, In step S3, the reducing atmosphere is hydrogen, hydrogen-argon mixture, or ammonia; the annealing temperature is 800 - 1000 °C, the annealing time is 0.5 - 3 h, and the heating rate during the annealing process is 2 - 10 °C / min.

8. The preparation method of the lead-modulated highly poison-resistant intermetallic compound bifunctional catalyst according to claim 2, characterized in that, In step S4, the acid solution is one or a mixture of sulfuric acid, hydrochloric acid, perchloric acid, and nitric acid, wherein the acid concentration is 0.1 - 1 mol / L.

9. The preparation method of the lead-modulated highly poison-resistant intermetallic compound bifunctional catalyst according to claim 8, characterized in that, The temperature for stirring treatment with the acid solution is 60 - 80 °C, and the time for stirring treatment with the acid solution is 0.25 - 4 h.

10. Application of a lead-modulated highly poison-resistant intermetallic compound bifunctional catalyst, characterized in that, The lead-modulated highly anti-poisoning intermetallic compound bifunctional catalyst described in claim 1 is used for catalyzing the oxygen reduction reaction at the cathode in a hydrogen fuel cell and / or catalyzing the methanol oxidation reaction at the anode in a direct methanol fuel cell.

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