Carbon-supported platinum-based intermetallic compound catalyst as well as preparation method and application thereof

Abstract

The invention provides a carbon-supported platinum-based intermetallic compound catalyst as well as a preparation method and application thereof, and belongs to the technical field of new energy catalytic materials and application. The preparation method provided by the invention comprises the following steps: after carrying out high-temperature graphitization treatment on a carbon black carrier, heating and refluxing by using a treating agent to obtain a pretreated carbon black carrier; then, dropwise adding a mixed solution of a nitrogen-containing heteroatom precursor and transition metal salt into the pretreated carbon black carrier to obtain a modified carbon black carrier; then, dropwise adding a platinum precursor solution into the modified carbon black carrier to obtain a catalyst precursor; and finally, carrying out reduction, alloying and ordering treatment on the catalyst precursor in a reducing atmosphere to obtain the carbon-loaded platinum-based intermetallic compound catalyst. The mass ratio activity of the catalyst reaches 0.48 A / mgPt, the mass ratio activity is attenuated by 6.0% after 30000 circles of potential circulation, and the catalyst has high activity and stability.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy catalytic materials and applications, and particularly relates to a carbon-supported platinum-based intermetallic compound catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Proton exchange membrane fuel cells (PEMFCs) have the advantages of being clean and environmentally friendly, having a low operating temperature, fast start-up and shut-down, high energy conversion efficiency, and low noise, and are one of the most promising green energy conversion devices. However, at present, there is still great room for improvement in the cost, lifespan, and power generation efficiency of PEMFCs. For example, the platinum-based catalyst, which is a key material required for the preparation of PEMFCs, still needs to be improved. The common commercial platinum-carbon catalyst has a high cost, and its performance and durability both need to be enhanced.

[0003] In the prior art, researchers alloyed Pt with transition metals (M) to improve the utilization efficiency of platinum and reduce the catalyst cost at the same time. However, the transition metals on the surface of the platinum alloy catalyst will dissolve in an environment intertwined with acidity, high potential, and oxidation, resulting in the performance decay of the catalyst, and the dissolved transition metal ions will poison the proton exchange membrane. Intermetallic compound catalysts show better durability than alloy catalysts. In intermetallic compounds, platinum and transition metals occupy fixed lattice sites and are arranged orderly, showing a higher mixing enthalpy and a stronger Pt(5d)-M(3d) orbital interaction, which helps to inhibit the dissolution and deactivation of Pt and transition metals in an environment intertwined with acidity, high potential, and oxidation, making such catalysts have better application prospects. However, due to the high surface free energy of platinum and the weak interaction between platinum and commercial carbon black carriers, platinum-based particles are prone to agglomeration during the high-temperature ordering process of the catalyst, resulting in a larger size of the formed platinum-based intermetallic compound, a decrease in the electrochemical active area of platinum, and ultimately a decrease in the performance of the catalyst. In addition, platinum precursors (chloroplatinic acid, potassium chloroplatinate, and sodium chloroplatinate) and some transition metal precursors (such as cobalt nitrate, cobalt chloride, iron nitrate, iron chloride, nickel nitrate, etc.) have different charged characteristics. Chloroplatinic acid root ions are negatively charged, while metal ions such as cobalt are positively charged. It is difficult to achieve the good adsorption of platinum precursors and transition metal precursors by carbon carriers simultaneously during the preparation of the catalyst.

[0004] In view of this, it is necessary to design a carbon-supported platinum-based intermetallic compound catalyst, a preparation method thereof, and an application thereof to solve the above problems. Summary of the Invention

[0005] In view of the technical problems existing in the background art, the present application provides a carbon-supported platinum-based intermetallic compound catalyst, a preparation method thereof and an application thereof, aiming to solve the technical problems that the size of the platinum-based intermetallic compound is relatively large, and it is difficult to simultaneously and preferably adsorb the platinum precursor and the transition metal precursor by the carbon support during the preparation of the catalyst. Among them, by introducing the transition metal and platinum step by step, the adsorption of platinum and the transition metal by the carbon support is promoted; by modifying the carbon black support with nitrogen-containing heteroatoms, the adsorption of the transition metal by the carbon support is promoted, and the anchoring ability of the carbon black support to the loaded metal is increased; the heteroatom-transition metal complex (such as cobalt-nitrogen-carbon) formed by modifying the carbon black support is beneficial to the deposition of platinum. The platinum-based intermetallic compound in the carbon-supported platinum-based intermetallic compound catalyst prepared by the present application is uniformly distributed on the carbon support and has a controllable size, and the mass specific activity of the catalyst in the electrocatalytic oxygen reduction reaction reaches 0.48 A / mg Pt , and the mass specific activity decays by 6.0% after 30,000 potential cycles, having high activity and stability.

[0006] In the first aspect, an embodiment of the present application provides a preparation method of a carbon-supported platinum-based intermetallic compound catalyst, including the following steps: S1, subject the carbon black support to high-temperature graphitization treatment, then add the treated carbon black support to a treating agent, mix evenly and heat under reflux, filter, wash and dry to obtain a pretreated carbon black support.

[0007] S2, uniformly disperse a nitrogen-containing heteroatom precursor and a transition metal salt in an organic alcohol solvent to obtain a mixed solution, drop the mixed solution into the pretreated carbon black support obtained in step S1, disperse evenly by ultrasonic treatment, remove the solvent by a combination of rotary evaporation and ultrasonic treatment, dry, and perform high-temperature treatment in an inert atmosphere to obtain a modified carbon black support.

[0008] S3, drop the platinum precursor solution into the modified carbon black support obtained in step S2, disperse evenly by ultrasonic treatment, remove the solvent by a combination of rotary evaporation and ultrasonic treatment, dry to obtain a catalyst precursor.

[0009] S4, perform reduction, alloying and ordering treatment on the catalyst precursor obtained in step S3 in a reducing atmosphere to obtain a carbon-supported platinum-based intermetallic compound catalyst.

[0010] Further, in step S1, the carbon black carrier is one of commercial XC-72R conductive carbon black, EC300J Ketjen black, EC600JD Ketjen black, ECP600JD Ketjen black, acetylene black, and BP-2000 porous carbon. The treating agent is one of hydrogen peroxide, nitric acid, sulfuric acid, a mixture of nitric acid and sulfuric acid, and a mixture of hydrochloric acid and hydrogen peroxide. The solid-liquid ratio of the carbon black carrier to the treating agent is 1 g:(30 - 300 mL). The high-temperature graphitization treatment means placing the carbon black carrier in a high-temperature furnace at 2000 - 2800 °C for 2 - 3 h. The temperature of the heating reflux treatment is 40 - 100 °C, and the treatment time is 3 - 15 h.

[0011] Further, in step S2, the organic alcohol solvent is one of methanol, ethanol, and propanol. The nitrogen-containing heteroatom precursor is one of hexamethylenetetramine, bipyridine, 2-methylimidazole, thiourea, and glutamic acid. The transition metal salt is one of cobalt nitrate, cobalt chloride, iron nitrate, iron chloride, nickel nitrate, nickel chloride, copper nitrate, copper chloride, cuprous chloride, and gallium chloride.

[0012] Further, in step S2, the mass ratio of the nitrogen-containing heteroatom precursor to the pretreated carbon black carrier is (100 - 300):(100 - 200). The mass ratio of the transition metal salt to the pretreated carbon black carrier is (10 - 150):(100 - 200).

[0013] Further, in step S2, the inert atmosphere is one of nitrogen, argon, and helium; the temperature of the high-temperature treatment is 400 - 800 °C, and the time is 1 - 4 h.

[0014] Further, in step S3, the mass concentration of the platinum precursor solution is 15 - 25 mg / mL; among them, the platinum precursor is one of chloroplatinic acid, potassium chloroplatinate, and sodium chloroplatinate, and the solvent is one of deionized water, methanol, ethanol, and acetone.

[0015] Further, in step S3, the mass ratio of platinum in the platinum precursor to the modified carbon black carrier is (75 - 350):(50 - 200).

[0016] Further, in step S4, the reducing atmosphere is one of hydrogen, hydrogen-argon mixture, and hydrogen-nitrogen mixture. The temperature of the reduction, alloying, and ordering treatment is 450 - 950 °C, the heating rate is 5 - 10 °C / min, and the treatment time is 0.5 - 6 h.

[0017] Second aspect, embodiments of the present application provide a carbon-supported platinum-based intermetallic compound catalyst, which is prepared according to the preparation method of the carbon-supported platinum-based intermetallic compound catalyst described in any of the foregoing solutions. The platinum content of the carbon-supported platinum-based intermetallic compound catalyst is 10-30 wt%, and the ratio of platinum atoms to transition metal atoms is (1-3):1. The average particle size of the carbon-supported platinum-based intermetallic compound catalyst is less than 4.5 nm.

[0018] Third aspect, embodiments of the present application provide an application of a carbon-supported platinum-based intermetallic compound catalyst, and the carbon-supported platinum-based intermetallic compound catalyst is used for the oxygen reduction reaction of a hydrogen fuel cell.

[0019] The beneficial effects of the present application are as follows: The present application provides a carbon-supported platinum-based intermetallic compound catalyst, a preparation method and an application thereof. Among them, the carbon black carrier is first pretreated to obtain a pretreated carbon black carrier, and then the carbon black carrier is modified with nitrogen-containing heteroatoms and transition metals to obtain a modified carbon black carrier. Then, platinum is loaded to obtain a catalyst precursor, and finally, the catalyst precursor is reduced, alloyed and ordered in a reducing atmosphere to obtain a carbon-supported platinum-based intermetallic compound catalyst.

[0020] (1) The present application uses nitrogen-containing heteroatoms to modify the carbon black carrier to promote the adsorption of the carbon carrier to the transition metal and increase the anchoring ability of the carbon black carrier to the loaded metal. First, the nitrogen-containing heteroatom precursor has a certain alkalinity, which can adjust the pH value of the reaction system to be higher than the isoelectric point of the carbon black carrier to facilitate the electrostatic adsorption of the transition metal. Second, there is a coordination effect between the heteroatom precursor and the transition metal, which is beneficial to the uniform dispersion and adsorption of the transition metal. Finally, the carbon carrier doped with heteroatoms has an increased anchoring ability to the loaded metal, which is beneficial to the effective deposition and combination of platinum and the transition metal on the carbon black carrier, and inhibits the migration, aggregation and sintering of platinum-based nanoparticles during high-temperature treatment, so as to prepare a carbon-supported intermetallic compound catalyst with a small size.

[0021] (2) The present application introduces the transition metal and platinum step by step to enable the carbon black carrier to better adsorb the transition metal and platinum. On the one hand, the charged characteristics of the transition metal precursor (such as cobalt ions) and the platinum precursor (such as chloroplatinate) are different, and the pH environment suitable for their adsorption is also different. Introducing them step by step can provide a suitable adsorption environment for the transition metal and platinum respectively. On the other hand, the heteroatom-transition metal complex (such as cobalt-nitrogen-carbon) formed by modifying the carbon black carrier is beneficial to the deposition of platinum, because the nitrogen sites in cobalt-nitrogen-carbon (Co-N-C) have lone pair electrons and electron-rich characteristics, and its lone pair electrons can form a coordination bond with the d orbit of platinum, which is beneficial to the combination of cobalt-nitrogen-carbon and the platinum precursor.

[0022] (3) The platinum-based intermetallic compound in the carbon-supported platinum-based intermetallic compound catalyst prepared in this application is evenly distributed on the carbon support and has an average particle size of less than 4.5 nm. The mass-specific activity of the catalyst in the electrocatalytic oxygen reduction reaction reaches 0.48 A / mg Pt , and the mass-specific activity decays by 6.0% after 30,000 potential cycles, showing high activity and stability. The preparation steps and production equipment of the catalyst are simple, and the reagents used have low costs, making it suitable for large-scale batch production.

[0023] 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 implementation manners of this application are specifically exemplified below. Description of the Drawings

[0024] In order to more clearly illustrate the technical solution of this application, 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.

[0025] Figure 1 XRD pattern of the carbon-supported platinum-based intermetallic compound catalysts prepared in Example 1 and Comparative Examples 1-6; Figure 2 TEM image of the carbon-supported platinum-based intermetallic compound catalyst prepared in Example 1; Figure 3 TEM image of the carbon-supported platinum-based intermetallic compound catalyst prepared in Comparative Example 2; Figure 4 LSV polarization curves of the carbon-supported platinum-based intermetallic compound catalysts prepared in Example 1 and Comparative Examples 1-5, and commercial platinum-carbon catalyst (20% Pt / C); Figure 5 Electrochemical performance comparison diagram of the carbon-supported platinum-based intermetallic compound catalyst prepared in Example 1 and commercial platinum-carbon catalyst (20% Pt / C) after 30,000 potential cycles. Detailed Description of the Preferred Embodiments

[0026] 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.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field 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.

[0028] 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.

[0029] Referring to "embodiments" herein means that specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appearing in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0030] 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 three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this text generally represents an "or" relationship between the associated objects before and after.

[0031] The key material required for preparing PEMFC, the platinum-based catalyst, still needs to be improved. The cost of common commercial platinum-carbon catalysts is relatively high, and both their performance and durability need to be enhanced. In the prior art, the transition metals on the surface of platinum alloy catalysts will dissolve in an environment intertwined with acidity, high potential, and oxidation, resulting in the performance degradation of the catalyst, and the dissolved transition metal ions will poison the proton exchange membrane, with poor durability. Intermetallic compound catalysts exhibit better durability compared to alloy catalysts. However, due to the relatively high surface free energy of platinum and the weak interaction between platinum and commercial carbon black carriers, during the high-temperature ordering process of the catalyst, platinum-based particles are prone to agglomeration, making the size of the formed platinum-based intermetallic compound relatively large, leading to a reduction in the electrochemical active area of platinum and ultimately resulting in a decrease in the performance of the catalyst. In addition, platinum precursors (such as chloroplatinic acid, sodium chloroplatinate, etc.) and transition metal precursors (such as cobalt nitrate, cobalt chloride, iron nitrate, iron chloride, nickel nitrate, etc.) have different charging characteristics, and it is difficult to simultaneously and preferably adsorb platinum precursors and transition metal precursors on carbon carriers during the preparation of the catalyst.

[0032] In order to solve the technical problem that the size of platinum-based intermetallic compounds is relatively large, and it is difficult to simultaneously and preferably adsorb platinum precursors and transition metal precursors on a carbon support during the preparation of catalysts, the present application provides a carbon-supported platinum-based intermetallic compound catalyst, its preparation method and application. Among them, by introducing transition metals and platinum step by step, the adsorption of platinum and transition metals on the carbon support is promoted; by modifying the carbon black support with nitrogen-containing heteroatoms, the adsorption of transition metals on the carbon support is promoted, and the anchoring ability of the carbon black support for the supported metals is increased; the heteroatom-transition metal complex (such as cobalt-nitrogen-carbon) formed by modifying the carbon black support is beneficial to the deposition of platinum.

[0033] In a first aspect, an embodiment of the present application provides a method for preparing a carbon-supported platinum-based intermetallic compound catalyst, including the following steps: S1, subject the carbon black support to high-temperature graphitization treatment, then add the treated carbon black support to a treating agent, mix evenly and heat under reflux, filter, wash, and dry to obtain a pretreated carbon black support.

[0034] In the embodiment of the present application, the carbon black support is one of commercial XC-72R conductive carbon black, EC-300J Ketjen black, EC600JD Ketjen black, ECP600JD Ketjen black, acetylene black, and BP-2000 porous carbon, and the treating agent is one of hydrogen peroxide, nitric acid, sulfuric acid, a mixture of nitric acid and sulfuric acid, and a mixture of hydrochloric acid and hydrogen peroxide. The solid-liquid ratio of the carbon black support to the treating agent is 1 g:(30 - 300 mL). The high-temperature graphitization treatment means placing the carbon black support in a high-temperature furnace at 2000 - 2800 °C for 2 - 3 h. The temperature of the heating under reflux treatment is 40 - 100 °C, and the treatment time is 3 - 15 h.

[0035] In the embodiment of the present application, the drying temperature is preferably 60 - 100 °C, and the drying time is preferably 12 - 24 h.

[0036] S2, uniformly disperse a nitrogen-containing heteroatom precursor and a transition metal salt in an organic alcohol solvent to obtain a mixed solution, drop the mixed solution onto the pretreated carbon black support obtained in step S1, disperse evenly by ultrasonic treatment, remove the solvent by a combination of rotary evaporation and ultrasonic treatment, dry, and perform high-temperature treatment in an inert atmosphere to obtain a modified carbon black support.

[0037] Among them, the preparation method of the mixed solution is preferably to uniformly disperse the nitrogen-containing heteroatom precursor and the transition metal salt in the organic alcohol solvent respectively to obtain a heteroatom precursor solution and a transition metal salt solution, and then drop the transition metal salt solution into the heteroatom precursor solution. The mass concentration of the heteroatom precursor solution is 20 - 25 mg / mL, and the mass concentration of the transition metal salt solution is 15 - 20 mg / mL.

[0038] In the embodiments of the present application, the mass ratio of the nitrogen-containing heteroatom precursor to the pretreated carbon black support is (100 - 300):(100 - 200), and the mass ratio of the transition metal salt to the pretreated carbon black support is (10 - 150):(100 - 200). The organic alcohol solvent is one of methanol, ethanol, and propanol. The nitrogen-containing heteroatom precursor is one of hexamethylenetetramine, bipyridine, 2-methylimidazole, thiourea, and glutamic acid, preferably hexamethylenetetramine, bipyridine, and 2-methylimidazole. The transition metal salt is one of cobalt nitrate, cobalt chloride, iron nitrate, iron chloride, nickel nitrate, nickel chloride, copper nitrate, copper chloride, cuprous chloride, and gallium chloride, preferably cobalt nitrate, cobalt chloride, iron nitrate, and nickel nitrate.

[0039] In the embodiments of the present application, the inert atmosphere refers to one of nitrogen, argon, and helium. The temperature of the high-temperature treatment is 400 - 800 °C, and the time is 1 - 4 h.

[0040] In the embodiments of the present application, the drying temperature is preferably 40 - 80 °C, and the drying time is preferably 6 - 15 h.

[0041] In the present application, the modification of the carbon black support with nitrogen-containing heteroatoms is to promote the adsorption of transition metals by the carbon support and increase the anchoring ability of the carbon black support for the supported metal. First, the nitrogen-containing heteroatom precursor has a certain basicity, which can adjust the pH value of the reaction system to be higher than the isoelectric point of the carbon black support, facilitating the electrostatic adsorption of transition metals. Second, there is a coordination effect between the heteroatom precursor and the transition metal, which is conducive to the uniform dispersion and adsorption of the transition metal. Finally, the carbon support doped with heteroatoms has an increased anchoring ability for the supported metal, which is beneficial to the effective deposition and combination of platinum and transition metals on the carbon black support, and inhibits the migration, aggregation, and sintering of platinum-based nanoparticles during the high-temperature treatment, so as to prepare a carbon-supported intermetallic compound catalyst with a small size.

[0042] In the present application, the stepwise introduction of transition metals and platinum is to enable the carbon black support to better adsorb transition metals and platinum. On the one hand, the charged characteristics of the transition metal precursor (such as cobalt ions) and the platinum precursor (such as chloroplatinate) are different, and the pH environment suitable for their adsorption is also different. The stepwise introduction can provide a suitable adsorption environment for transition metals and platinum respectively. On the other hand, the heteroatom-transition metal complex (such as cobalt-nitrogen-carbon) formed by modifying the carbon black support is beneficial to the deposition of platinum because the nitrogen sites in cobalt-nitrogen-carbon (Co-N-C) have lone pair electrons and electron-rich characteristics, and their lone pair electrons can form coordination bonds with the d orbitals of platinum, which is conducive to the combination of cobalt-nitrogen-carbon and the platinum precursor.

[0043] S3. Drop the platinum precursor solution into the modified carbon black support obtained in step S2, ultrasonically disperse it evenly, remove the solvent by rotary evaporation combined with ultrasonication, and dry it to obtain the catalyst precursor.

[0044] In the embodiments of the present application, the mass concentration of the platinum precursor solution is 15 - 25 mg / mL, and the mass ratio of platinum in the platinum precursor to the modified carbon black support is (75 - 350):(50 - 200). Among them, the platinum precursor is one of chloroplatinic acid, potassium chloroplatinate, and sodium chloroplatinate, and the solvent is one of deionized water, methanol, ethanol, and acetone.

[0045] In the embodiments of the present application, the drying temperature is preferably 40 - 80 °C, and the drying time is preferably 5 - 15 h.

[0046] S4. Under a reducing atmosphere, the catalyst precursor obtained in step S3 is subjected to reduction, alloying, and ordering treatments to obtain a carbon-supported platinum-based intermetallic compound catalyst.

[0047] In the embodiments of the present application, the temperature for reduction, alloying, and ordering treatments is 450 - 950 °C, the heating rate is 5 - 10 °C / min, and the treatment time is 0.5 - 6 h. The reducing atmosphere is one of hydrogen, hydrogen-argon mixture, and hydrogen-nitrogen mixture.

[0048] In the second aspect, the embodiments of the present application provide a carbon-supported platinum-based intermetallic compound catalyst, which is prepared according to the preparation method of any one of the foregoing schemes. The platinum content of the catalyst is 10 - 30 wt%, the ratio of platinum atoms to transition metal atoms is (1 - 3):1, and the average particle size of the catalyst is less than 4.5 nm.

[0049] In the third aspect, the carbon-supported platinum-based intermetallic compound catalyst provided by the embodiments of the present application is used for the oxygen reduction reaction of a hydrogen fuel cell.

[0050] The following are some specific examples. It should be noted that the examples 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 where specific technologies or conditions are not indicated in the examples, the technologies or conditions described in the literature in the art or according to the product specifications are followed. For reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through commercial purchase.

[0051] Example 1 Example 1 provides a preparation method of a carbon-supported platinum-based intermetallic compound catalyst, including the following steps: S1. Place 2 g of commercial carbon black (XC-72R) in a high-temperature furnace and treat it at 2800 °C for 2.5 h for high-temperature graphitization treatment. Then, add the treated carbon black support to 120 mL of concentrated nitric acid, mix evenly, heat and reflux at 100 °C for 5 h, filter, wash with deionized water, and dry overnight (15 h) at 80 °C to obtain a pretreated carbon black support.

[0052] S2. Uniformly disperse 120 mg of hexamethylenetetramine in 5 mL of methanol to obtain a heteroatom precursor solution, and uniformly disperse 52 mg of cobalt nitrate in 3 mL of methanol to obtain a transition metal salt solution. Drop the transition metal salt solution into the heteroatom precursor and ultrasonically disperse it evenly to obtain a mixed solution. Then, take 100 mg of the pretreated carbon black support obtained in step S1 and put it into an evaporation flask, drop the aforementioned mixed solution, ultrasonically disperse it evenly, remove the solvent by rotary evaporation combined with ultrasonic treatment, place the product in a blast drying oven and dry it at 60 °C for 8 h, and then place it in argon and treat it at 500 °C for 2 h to obtain a modified carbon black support.

[0053] S3. Dissolve 98 mg of chloroplatinic acid in 5 mL of methanol solution to prepare a platinum precursor solution. Take 64 mg of the modified carbon black support obtained in step S2 into a flask, drop in the platinum precursor solution, ultrasonically disperse it evenly, and then remove the solvent by rotary evaporation combined with ultrasonic treatment. Place the product in a blast drying oven and dry it at 60 °C for 6 h to obtain a catalyst precursor.

[0054] S4. Place the catalyst precursor obtained in step S3 in a quartz crucible and place it in a tube furnace. Treat it at 600 °C for 2.5 h in a hydrogen-argon mixed atmosphere (containing 5% H 2 ) for reduction, alloying, and ordering treatment to obtain a carbon-supported platinum-based intermetallic compound catalyst.

[0055] Example 2 Example 2 provides a method for preparing a carbon-supported platinum-based intermetallic compound catalyst, which includes the following steps: S1. Place 2 g of commercial carbon black (XC-72R) in a high-temperature furnace and treat it at 2000 °C for 2 h for high-temperature graphitization treatment. Then, add the treated carbon black support to 120 mL of concentrated nitric acid, mix evenly, heat and reflux at 90 °C for 5 h, filter, wash with deionized water, and dry at 80 °C overnight (15 h) to obtain a pretreated carbon black support.

[0056] S2. Uniformly disperse 240 mg of bipyridine in 10 mL of methanol to obtain a heteroatom precursor solution, and uniformly disperse 102 mg of cobalt nitrate in 6 mL of methanol to obtain a transition metal salt solution. Drop the transition metal salt solution into the heteroatom precursor and ultrasonically disperse it evenly to obtain a mixed solution. Then, take 200 mg of the pretreated carbon black support obtained in step S1 and put it into an evaporation flask, drop the aforementioned mixed solution, ultrasonically disperse it evenly, remove the solvent by rotary evaporation combined with ultrasonic treatment, place the product in a blast drying oven and dry it at 60 °C for 8 h, and then place it in argon and treat it at 500 °C for 2 h to obtain a modified carbon black support.

[0057] S3. Dissolve 98 mg of chloroplatinic acid in 5 mL of methanol solution to prepare a platinum precursor solution. Take 64 mg of the modified carbon black support obtained in step S2 into a flask, drop in the platinum precursor solution, disperse it evenly by ultrasonic treatment, then remove the solvent by rotary evaporation combined with ultrasonic treatment, and place the product in a forced-air drying oven at 60 °C for 6 h to obtain a catalyst precursor.

[0058] S4. Place the catalyst precursor obtained in step S3 in a quartz crucible and put it into a tube furnace. Treat it at 600 °C for 2.5 h in a hydrogen-argon mixed atmosphere (containing 5% H 2 ) to carry out reduction, alloying and ordering treatments to obtain a carbon-supported platinum-based intermetallic compound catalyst.

[0059] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the amount of cobalt used in step S2 is reduced. Specifically, 20 mg of cobalt nitrate is evenly dispersed in 3 mL of methanol to obtain a transition metal salt solution. The others are the same as in Example 1 and will not be elaborated here.

[0060] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the carbon black support is not modified and the transition metal and platinum are loaded simultaneously. It specifically includes the following steps: S1. Place 2 g of commercial carbon black (XC-72R) in a high-temperature furnace and treat it at 2800 °C for 2.5 h for high-temperature graphitization treatment. Then, add the treated carbon black support to 120 mL of concentrated nitric acid, mix evenly, heat and reflux at 100 °C for 5 h, filter, wash with deionized water, and dry overnight (15 h) at 80 °C to obtain a pretreated carbon black support.

[0061] S2. Dissolve 98 mg of chloroplatinic acid and 29 mg of cobalt nitrate in 5 mL of methanol solution to prepare a platinum-cobalt precursor solution. Take 58 mg of the pretreated carbon black support obtained in step S1 into a flask, drop in the platinum-cobalt precursor solution, disperse it evenly by ultrasonic treatment, then remove the solvent by rotary evaporation combined with ultrasonic treatment, and place the product in a forced-air drying oven at 60 °C for 6 h to obtain a catalyst precursor.

[0062] S3. Place the catalyst precursor obtained in step S2 in a quartz crucible and put it into a tube furnace. Treat it at 600 °C for 2.5 h in a hydrogen-argon mixed atmosphere (containing 5% H 2 ) to carry out reduction, alloying and ordering treatments to obtain a carbon-supported platinum-based intermetallic compound catalyst.

[0063] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the carbon black support is not modified and no transition metal is loaded. It specifically includes the following steps: S1. Place 2 g of commercial carbon black (XC-72R) in a high-temperature furnace and treat it at 2800 °C for 2.5 h for high-temperature graphitization treatment. Then, add the treated carbon black support to 120 mL of concentrated nitric acid, mix evenly, heat under reflux at 100 °C for 5 h, filter, wash with deionized water, and dry overnight (15 h) at 80 °C to obtain the pretreated carbon black support.

[0064] S2. Dissolve 98 mg of chloroplatinic acid in 5 mL of methanol solution to prepare a platinum precursor solution. Take 64 mg of the pretreated carbon black support obtained in step S1 into a flask, drop in the platinum precursor solution, disperse it evenly by ultrasonic treatment, then remove the solvent by rotary evaporation combined with ultrasonic treatment, and place the product in a forced-air drying oven at 60 °C for 6 h to obtain a catalyst precursor.

[0065] S3. Place the catalyst precursor obtained in step S2 in a quartz crucible and place it in a tube furnace. Treat it at 600 °C for 2.5 h in a hydrogen-argon mixed atmosphere (containing 5% H 2 ) for reduction, alloying, and ordering treatment to obtain a carbon-supported platinum-based intermetallic compound catalyst.

[0066] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that only the carbon black support is modified with heteroatoms, and the transition metal and platinum are loaded simultaneously, which specifically includes the following steps: S1. Place 2 g of commercial carbon black (XC-72R) in a high-temperature furnace and treat it at 2800 °C for 2.5 h for high-temperature graphitization treatment. Then, add the treated carbon black support to 120 mL of concentrated nitric acid, mix evenly, heat under reflux at 100 °C for 5 h, filter, wash with deionized water, and dry overnight (15 h) at 80 °C to obtain the pretreated carbon black support.

[0067] S2. Disperse 120 mg of hexamethylenetetramine evenly in 5 mL of methanol to obtain a heteroatom precursor solution. Then, take 100 mg of the pretreated carbon black support obtained in step S1 and put it into an evaporation flask, drop in the heteroatom precursor solution, disperse it evenly by ultrasonic treatment, remove the solvent by rotary evaporation combined with ultrasonic treatment, place the product in a forced-air drying oven at 60 °C for 8 h, and then place it in argon at 500 °C for 2 h to obtain a modified carbon black support.

[0068] S3. Dissolve 98 mg of chloroplatinic acid and 29 mg of cobalt nitrate in 5 mL of methanol solution to prepare a platinum-cobalt precursor solution. Take 58 mg of the modified carbon black support obtained in step S2 into a flask, drop in the platinum-cobalt precursor solution, disperse it evenly by ultrasonic treatment, then remove the solvent by rotary evaporation combined with ultrasonic treatment, and place the product in a forced-air drying oven at 60 °C for 6 h to obtain a catalyst precursor.

[0069] S4. Place the catalyst precursor obtained in step S3 in a quartz crucible and place it in a tube furnace. Treat it at 600 °C for 2.5 h in a hydrogen-argon mixed atmosphere (containing 5% H 2 ) to perform reduction, alloying, and ordering treatments to obtain a carbon-supported platinum-based intermetallic compound catalyst.

[0070] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that only the carbon black support is modified with a transition metal, which specifically includes the following steps: S1. Place 2 g of commercial carbon black (XC-72R) in a high-temperature furnace and treat it at 2800 °C for 2.5 h to perform high-temperature graphitization treatment. Then, add the treated carbon black support to 120 mL of concentrated nitric acid, mix evenly, heat under reflux at 100 °C for 5 h, filter, wash with deionized water, and dry overnight (15 h) at 80 °C to obtain a pretreated carbon black support.

[0071] S2. Disperse 52 mg of cobalt nitrate evenly in 3 mL of methanol to obtain a transition metal salt solution. Then, take 100 mg of the pretreated carbon black support obtained in step S1 and put it into an evaporation flask. Dropwise add the transition metal salt solution, disperse it evenly by ultrasonic treatment, remove the solvent by rotary evaporation combined with ultrasonic treatment, place the product in a blast drying oven and dry it at 60 °C for 8 h, and then place it in argon and treat it at 500 °C for 2 h to obtain a modified carbon black support.

[0072] S3. Dissolve 98 mg of chloroplatinic acid in 5 mL of methanol solution to prepare a platinum precursor solution. Take 64 mg of the modified carbon black support obtained in step S2 into a flask, dropwise add the platinum precursor solution, disperse it evenly by ultrasonic treatment, then remove the solvent by rotary evaporation combined with ultrasonic treatment, place the product in a blast drying oven and dry it at 60 °C for 6 h to obtain a catalyst precursor.

[0073] S4. Place the catalyst precursor obtained in step S3 in a quartz crucible and place it in a tube furnace. Treat it at 600 °C for 2.5 h in a hydrogen-argon mixed atmosphere (containing 5% H 2 ) to perform reduction, alloying, and ordering treatments to obtain a carbon-supported platinum-based intermetallic compound catalyst.

[0074] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that only the modified carbon black support is prepared, that is, steps S1-S2 are retained, steps S3-S4 are deleted, and the others are the same as in Example 1, which will not be elaborated here.

[0075] The crystal phase structures of the carbon-supported platinum-based intermetallic compound catalysts prepared in Example 1 and Comparative Examples 1-6 and the commercial platinum-carbon catalyst (20% Pt / C) were characterized by X-ray diffraction method. The obtained XRD patterns are shown in Figure 1As shown. It can be seen that diffraction peaks appear near the diffraction angles of 41.4°, 47.8°, 70.4°, and 85.0° in the spectrogram of Example 1, corresponding to the Pt(111), Pt(200), Pt(220), and Pt(311) crystal planes respectively. Moreover, an obvious superlattice characteristic peak appears near the diffraction angle of 33.3°, indicating that the platinum-cobalt intermetallic compound has been successfully prepared in this application. Compared with Example 1, the diffraction peaks corresponding to the Pt(111), Pt(200), Pt(220), and Pt(311) crystal planes of the sample in Comparative Example 1 shift to the left, corresponding to the Pt 3 Co intermetallic compound, but the superlattice peak is weak, indicating that too little addition of Co is not conducive to the formation of the platinum-cobalt intermetallic compound. The spectrograms of Comparative Example 2, Comparative Example 4, and Comparative Example 5 conform to the crystal structure characteristics of the platinum-cobalt intermetallic compound. There is no superlattice characteristic peak in the spectrogram of Comparative Example 3, which does not belong to the intermetallic compound. Compared with the spectrograms of Comparative Example 2, Comparative Example 4, and Comparative Example 5, the relative intensity of the platinum superlattice peak (33.3°) and the Pt(111) diffraction peak (41.4°) in Example 1 is higher. The diffraction peak (41.4°) corresponding to the Pt(111) crystal plane shifts to the right and the diffraction peak is wider, indicating that the prepared catalyst in Example 1 has a higher degree of order and smaller grain size. Comparative Example 6 only has characteristic peaks corresponding to the graphitized carbon black support, does not contain platinum metal, has no activity in acidic medium, and has no significance for testing the reaction activity.

[0076] The carbon-supported platinum-based intermetallic compound catalysts prepared in Example 1 and Comparative Example 2 were characterized by transmission electron microscopy, and the obtained TEM images are shown in Figures 2 to 3 As shown. It can be seen that Figure 2 in Example 1, the platinum-cobalt nanoparticles of the catalyst are uniformly distributed in the support, while Figure 3 in Comparative Example 2, obvious sintering exists in the catalyst, indicating that the method of first introducing heteroatoms and transition metals and then introducing platinum in this application limits the deposition of platinum-cobalt on the carbon black support while achieving effective binding of platinum and cobalt, and improves the dispersion state of platinum-based nanoparticles on the support.

[0077] The oxygen reduction reaction activities of the carbon-supported platinum-based intermetallic compound catalysts prepared in Examples 1-2 and Comparative Examples 1-5 and the commercial platinum-carbon catalyst (20% Pt / C) were tested by linear sweep voltammetry (LSV). The specific steps are as follows: Add to 0.1mol / L HClO 4High-purity oxygen is introduced into the solution and purged for at least 30 min to saturate the oxygen. Then, the working electrode coated with the catalyst is placed. First, the catalyst is activated at a scanning rate of 100 mV / s until the CV curves coincide. Then, the RDE rotation speed is adjusted to 1600 r / min, and within the potential range of 0.05 - 1.1 V (v.s. RHE), a forward scan is performed at a speed of 10 mV / s to record the ORR polarization curve. Please refer to Figure 4 As shown, the LSV polarization curve obtained by testing shows that the mass specific activity of the catalyst in Example 1 reaches 0.48 A / mg Pt , significantly better than those of Comparative Examples 1 - 5 (0.17 to 0.26 / mg Pt ) and the commercial Pt / C catalyst (0.12 A / mg Pt ).

[0078] The performance stability of the carbon-supported platinum-based intermetallic compound catalyst prepared in Example 1 and the commercial Pt / C catalyst (20% Pt / C) was tested. Specifically, high-purity oxygen was introduced into a 0.1 mol / L HClO 4 solution and purged for at least 30 min to saturate the nitrogen. Then, the working electrode coated with the catalyst was placed. First, the catalyst was scanned 30,000 cycles at a scanning rate of 100 mV / s. Then, high-purity oxygen was introduced into a 0.1 mol / L HClO 4 solution and purged for at least 30 min to saturate the oxygen. First, the catalyst was activated at a scanning rate of 100 mV / s until the CV curves coincided. Then, the RDE rotation speed was adjusted to 1600 r / min, and within the potential range of 0.05 - 1.1 V (v.s. RHE), a forward scan was performed at a speed of 10 mV / s to record the ORR polarization curve. Please refer to Figure 5 As shown, it is the electrochemical performance comparison diagram after the catalyst has experienced 30,000 potential cycles. It can be seen that the mass specific activity of the catalyst prepared in Example 1 only decays by 6.0%, while the mass specific activity of the commercial Pt / C catalyst decays by 41.0%.

[0079] The performance summary of the commercial Pt / C catalyst and the carbon-supported platinum-based intermetallic compound catalysts prepared in Examples 1 - 2 and Comparative Examples 1 - 5 is shown in the following table.

[0080] In summary, the present application provides a carbon-supported platinum-based intermetallic compound catalyst, its preparation method and application. First, the carbon black support is pretreated to obtain a pretreated carbon black support, then the carbon black support is modified with nitrogen heteroatoms and transition metals to obtain a modified carbon black support. Next, platinum is loaded to obtain a catalyst precursor, and finally, the catalyst precursor is reduced, alloyed and ordered in a reducing atmosphere to obtain a carbon-supported platinum-based intermetallic compound catalyst. The platinum-based intermetallic compound in the carbon-supported platinum-based intermetallic compound catalyst prepared in the present application is uniformly distributed on the carbon support and has a controllable size. The mass specific activity of the catalyst in the electrocatalytic oxygen reduction reaction reaches 0.48 A / mg Pt , and the mass specific activity decays by 6.0% after 30,000 potential cycles, showing high activity and stability.

[0081] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same composition and the same effect as the technical idea within the technical solution scope of the present application are included in the technical scope of the present application. In addition, within the scope not departing from the gist of the present application, various modifications that can be conceived by those skilled in the art 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 method for preparing a carbon-supported platinum-based intermetallic compound catalyst, characterized in that: The steps include: S1, subjecting the carbon black carrier to high temperature graphitization treatment, then adding the treated carbon black carrier to the treating agent, mixing evenly, heating under reflux, filtering, washing, and drying to obtain the pretreated carbon black carrier; S2, uniformly dispersing a nitrogen-containing heteroatom precursor and a transition metal salt in an organic alcohol solvent to obtain a mixed solution, dropping the mixed solution into the pretreated carbon black carrier obtained in step S1, uniformly dispersing by ultrasound, removing the solvent by rotary evaporation combined with ultrasound, drying, and performing high-temperature treatment in an inert atmosphere to obtain a modified carbon black carrier; S3, adding the platinum precursor solution dropwise to the modified carbon black carrier obtained in step S2, dispersing it evenly by ultrasonication, removing the solvent by rotary evaporation combined with ultrasonication, and drying to obtain a catalyst precursor; S4, reducing, alloying and ordering the catalyst precursor obtained in step S3 under a reducing atmosphere to obtain a carbon-supported platinum-based intermetallic compound catalyst.

2. The method for preparing a carbon-supported platinum-based intermetallic compound catalyst according to claim 1, characterized in that: In step S1, the carbon black carrier is one of commercial XC-72R conductive carbon black, EC300J Ketjen black, EC600JD Ketjen black, ECP600JD Ketjen black, acetylene black, and BP-2000 porous carbon; the treatment agent is one of hydrogen peroxide, nitric acid, sulfuric acid, a mixture of nitric acid and sulfuric acid, and a mixture of hydrochloric acid and hydrogen peroxide; the solid-liquid ratio of the carbon black carrier to the treatment agent is 1g:(30-300mL); the high-temperature graphitization treatment refers to placing the carbon black carrier in a high-temperature furnace at 2000-2800°C for 2-3h; the temperature of the heating reflux treatment is 40-100°C, and the treatment time is 3-15h.

3. The method for preparing the carbon-supported platinum-based intermetallic compound catalyst according to claim 1, characterized in that: In step S2, the organic alcohol solvent is one of methanol, ethanol, and propanol; the nitrogen-containing heteroatom precursor is one of hexamethylenetetramine, bipyridine, 2-methylimidazole, thiourea, and glutamic acid; and the transition metal salt is one of cobalt nitrate, cobalt chloride, ferric nitrate, ferric chloride, nickel nitrate, nickel chloride, copper nitrate, cupric chloride, cuprous chloride, and gallium chloride.

4. The method for preparing the carbon-supported platinum-based intermetallic compound catalyst according to claim 3, characterized in that: In step S2, the mass ratio of the nitrogen-containing heteroatom precursor to the pretreated carbon black carrier is (100-300): (100-200); the mass ratio of the transition metal salt to the pretreated carbon black carrier is (10-150): (100-200).

5. The method for preparing the carbon-supported platinum-based intermetallic compound catalyst according to claim 1, characterized in that: In step S2, the inert atmosphere refers to one of nitrogen, argon and helium; the temperature of the high temperature treatment is 400-800°C and the time is 1-4h.

6. The method for preparing a carbon-supported platinum-based intermetallic compound catalyst according to claim 1, characterized in that: In step S3, the mass concentration of the platinum precursor solution is 15-25 mg / mL; wherein the platinum precursor is one of chloroplatinic acid, potassium chloroplatinate, and sodium chloroplatinate, and the solvent is one of deionized water, methanol, ethanol, and acetone.

7. The method for preparing the carbon-supported platinum-based intermetallic compound catalyst according to claim 6, characterized in that: In step S3, the mass ratio of platinum in the platinum precursor to the modified carbon black carrier is (75-350): (50-200).

8. The method for preparing a carbon-supported platinum-based intermetallic compound catalyst according to claim 1, characterized in that: In step S4, the reducing atmosphere is one of hydrogen, hydrogen-argon mixed gas, and hydrogen-nitrogen mixed gas; the temperature of the reduction, alloying and ordering treatment is 450-950°C, the heating rate is 5-10°C / min, and the treatment time is 0.5-6h.

9. A carbon-supported platinum-based intermetallic compound catalyst, characterized in that: The carbon-supported platinum-based intermetallic compound catalyst is prepared according to the preparation method of the carbon-supported platinum-based intermetallic compound catalyst described in any one of claims 1-8, the platinum content of the carbon-supported platinum-based intermetallic compound catalyst is 10-30 wt%, and the ratio of platinum atoms to transition metal atoms is (1-3):1; the average particle size of the carbon-supported platinum-based intermetallic compound catalyst is less than 4.5 nm.

10. Use of the carbon-supported platinum-based intermetallic compound catalyst according to claim 9, characterized in that: The carbon-supported platinum-based intermetallic compound catalyst is used for oxygen reduction reaction in a hydrogen fuel cell.

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