Post-treatment method of carbon-supported platinum-based catalyst

Abstract

The invention provides a post-treatment method of a carbon-supported platinum-based catalyst, and relates to the technical field of energy materials. The method comprises the following steps: carrying out air etching treatment on the catalyst to remove surface carbon deposition, carrying out acid treatment and reducing atmosphere treatment to induce oxidized metal on the surface of the catalyst to be alloyed again and form a platinum skin, and carrying out post-treatment to obtain the catalyst which has a core-shell structure, a shell on the surface of a nanoparticle is the platinum skin, and a core in the nanoparticle is alloy. The post-treatment method provided by the invention is suitable for the carbon-loaded platinum-based catalyst with the platinum loading capacity of 10-80 wt% and the alloy of a binary / ternary alloy containing transition metal, after the post-treated catalyst is applied to a cathode of a proton membrane fuel cell, the cell performance can be greatly improved, and the peak power density can be improved by 0.36 W cm <-2 >.

Description

Technical Field

[0001] The invention relates to the technical field of energy materials, and in particular to a post-treatment method of a carbon-supported platinum-based catalyst. Background Art

[0002] Proton exchange membrane fuel cell (PEMFC) is a highly efficient energy conversion device. Although it has the advantages of high efficiency, high energy density, abundant fuel sources and environmental friendliness, its cathode oxygen reduction reaction (ORR) rate is slow, which restricts the performance improvement of PEMFC. Carbon-supported platinum-based catalysts enhance the ORR activity of the PEMFC cathode by alloying platinum with transition metals (such as cobalt, nickel, etc.), but this type of catalyst is not stable enough in an acidic environment, which affects its practical application in PEMFC. For example, high temperature, high voltage and acidic environment can easily cause transition metal dissolution, resulting in the destruction of the catalyst structure and the attenuation of activity; the transition metal present on the catalyst surface will reduce the electrochemical active area of ​​the catalyst, affecting its performance in actual energy conversion devices.

[0003] In the prior art, the patent publication number CN119133473A discloses a membrane electrode heat treatment method for changing the ionomer clusters in the catalyst layer and its application. By heat treating and acid treating the membrane electrode, the mobility of the main chain and side chain of the ionomer in the catalyst layer is improved to varying degrees, and the ohmic loss is reduced, thereby improving the overall electrolytic performance of the membrane electrode. However, the time and conditions of the acid leaching treatment are often difficult to accurately control, and excessive acid treatment may lead to a decrease in catalyst performance. There are also schemes in the prior art to change the surface state of the catalyst by heat treatment under a reducing atmosphere, but the reducing ability of hydrogen at high temperature is limited, and the purification effect on the catalyst surface is insufficient. If you want to achieve a better post-processing effect, the requirements for equipment are often high.

[0004] In view of this, it is necessary to design a post-treatment method for carbon-supported platinum-based catalysts to solve the above technical problems. Summary of the invention

[0005] The purpose of the present invention is to provide a post-treatment method for a carbon-supported platinum-based catalyst, which first performs air etching treatment on the carbon-supported platinum-based catalyst to remove carbon deposits on the catalyst surface, and then performs acid treatment and reducing atmosphere treatment to induce the oxidized metal on the catalyst surface to alloy again, so that the post-treated catalyst presents a core-shell structure, that is, the surface of the nanoparticle is wrapped with a uniform layer of platinum skin (shell), and the interior of the nanoparticle is an alloy (core). The half-wave potential of the post-treated catalyst in an acidic environment can be increased by 12mV, the specific mass activity can be increased by 2.1 times, and the peak power density can be increased by 0.36W cm in actual fuel cell operation. -2 .

[0006] To achieve the above-mentioned purpose of the invention, the present invention provides a post-treatment method of a carbon-supported platinum-based catalyst, firstly air-etching the carbon-supported platinum-based catalyst to remove carbon deposits on the catalyst surface, then acid-treating and reducing atmosphere-treating to induce the oxidized metal on the catalyst surface to alloy again and form a platinum skin, and the catalyst obtained by post-treatment presents a core-shell structure, the shell on the surface of the nanoparticles is a platinum skin, and the core inside is an alloy. The alloy is a binary or ternary alloy containing a transition metal. The loading amount of platinum in the carbon-supported platinum-based catalyst is 10-80wt%.

[0007] Furthermore, the carbon carrier of the carbon-supported platinum-based catalyst is nanocarbon black, carbon nanotubes or graphitized carbon black.

[0008] Furthermore, the alloy contains one or two of platinum, manganese, iron, copper, nickel, zinc, cobalt and molybdenum.

[0009] Furthermore, the air etching treatment refers to placing the carbon-supported platinum-based catalyst in an air atmosphere at 200-500° C. for 0.5-4 hours.

[0010] Furthermore, the acid treatment refers to placing the carbon-supported platinum-based catalyst that has been treated with air etching into an acidic solution and ultrasonically dispersing it uniformly, stirring it at 50-90° C. for 0.5-24 hours, then adding deionized water for washing, filtering it to obtain a filter cake and drying it.

[0011] Furthermore, the reducing atmosphere treatment refers to grinding the catalyst treated with air etching and acid into powder and placing it in a reducing atmosphere, heating it to 150-550° C. at a rate of 1-15° C. / min, and then heat-treating it for 0.5-3 h.

[0012] Furthermore, the equipment used for the air etching is a tubular furnace.

[0013] Furthermore, the acidic solution refers to an aqueous solution with an acid concentration of 0.01-1.5 mol / L, wherein the acid is one or more of nitric acid, sulfuric acid, hydrochloric acid, perchloric acid, and acetic acid.

[0014] Furthermore, in the acid treatment, nitric acid or perchloric acid is used as the acid, and the stirring time is 4-16 hours.

[0015] Furthermore, the reducing atmosphere is a hydrogen-argon mixed gas, wherein the volume fraction of hydrogen is 0.5%-15%.

[0016] The beneficial effects of the present invention are: The present invention provides a post-treatment method for a carbon-supported platinum-based catalyst, which utilizes the synergistic effect of three treatment processes, namely, air etching treatment, acid treatment and reducing atmosphere treatment, so that the catalyst surface is fully purified, and the post-treated catalyst presents a core-shell structure, the surface of the nanoparticle is coated with a uniform platinum skin (shell), and the interior of the nanoparticle is an alloy (core).

[0017] (1) The purpose of air etching on carbon-supported platinum-based catalysts is to remove carbon deposits on the catalyst surface and fully expose the active sites, which is beneficial for subsequent alloying treatment.

[0018] (2) The purpose of acid treatment and reducing atmosphere treatment of carbon-supported platinum-based catalysts is to fully purify the catalyst surface and induce the oxidized metal on the catalyst surface to alloy again and form a platinum skin. Acid treatment can form a platinum-rich skeleton of the catalyst, but at this time the catalyst surface is uneven and has holes, and the core-shell structure has not been completely formed. Reducing atmosphere treatment can further rearrange the atoms on the metal surface, so that a uniform and smooth platinum skin exists on the catalyst surface. In this way, the catalytic activity, stability, mass transfer and conductivity of the catalyst are all improved, and the enrichment of platinum on the catalyst surface can reduce the platinum loading and reduce the preparation cost.

[0019] (3) The post-treatment process provided by the present invention is simple and easy to operate, highly operable, and suitable for industrial production. The post-treated carbon-supported platinum-based catalyst is suitable for ORR reaction in acidic medium, and the ORR electrocatalytic activity is significantly improved. For example, after post-treatment, the half-wave potential of the PtCo / C catalyst in Example 1 in an acidic environment is increased by 12 mV, and the specific mass activity is increased by 2.1 times. In addition, the catalyst has been successfully applied to the cathode of a proton membrane fuel cell, and the peak power density is increased by 0.36 W cm in actual fuel cell operation. -2 , which fully demonstrates that the post-processing method provided in this application can greatly improve the performance of the product in battery applications, and is of great significance for reducing production costs and promoting large-scale commercial applications of fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The XRD spectra of the catalyst before and after treatment in Example 1 of the present application; Figure 2 This is a TEM image of the catalyst before treatment and after treatment in Example 1 of the present application; Figure 3 The ordered L1 of the catalyst metal nanoparticles after treatment in Example 1 of the present application 2 Superlattice structure diagram (A) and HAADF-STEM image of the treated catalyst product (B); Figure 4It is a comparison diagram of the rotating disk polarization curves of the commercial Pt / C catalyst, Example 1 and the catalysts of Comparative Examples 1-2 in the present application in an acid medium; Figure 5 This is a comparison diagram of the rotating disk polarization curves of the commercial Pt / C catalyst and the catalyst of Example 2 in the present application in an acid medium; Figure 6 This is a comparison diagram of the rotating disk polarization curves of the commercial Pt / C catalyst and the catalyst of Example 3 in the present application in an acid medium; Figure 7 This is a comparison chart of CV curves of the commercial Pt / C catalyst in this application and the catalyst of Example 1 in an acid medium; Figure 8 This is a comparison chart of CV curves of the commercial Pt / C catalyst in this application and the catalyst of Example 2 in an acid medium; Fig. 9 This is a comparison chart of CV curves of the commercial Pt / C catalyst in this application and the catalyst of Example 3 in an acid medium; Fig.10 This is a comparison diagram of the electrochemical active area of ​​the catalyst of Example 1 before and after treatment calculated by the present application; Fig.11 This is a comparison diagram of the steady-state polarization curves and power density curves of the catalyst before treatment and the catalyst after treatment in the hydrogen-oxygen fuel cell in Application Examples 1-2 of this application. DETAILED DESCRIPTION

[0021] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0023] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0024] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0026] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0027] Carbon-supported platinum-based catalysts enhance the ORR activity of the PEMFC cathode by alloying platinum with transition metals (such as cobalt and nickel), but this type of catalyst is not stable enough in an acidic environment, which affects its practical application in PEMFC. For example, high temperature, high voltage and acidic environment can easily cause the dissolution of transition metals, resulting in the destruction of the catalyst structure and the attenuation of activity; the presence of transition metals on the catalyst surface will reduce the electrochemical active area of ​​the catalyst, affecting its performance in actual energy conversion devices.

[0028] In the prior art, there are schemes for changing the surface state of the catalyst by acid treatment or heat treatment in a reducing atmosphere. However, on the one hand, the time and conditions of the acid leaching treatment are often difficult to control accurately, and excessive acid treatment may lead to a decrease in catalyst performance. On the other hand, the reducing ability of hydrogen at high temperature is limited, and the purification effect on the catalyst surface is insufficient. If a better post-treatment effect is to be achieved, the requirements for equipment are often high.

[0029] In order to solve the above-mentioned technical problems, the present application embodiment provides a post-treatment method of a carbon-supported platinum-based catalyst, which utilizes the synergistic effect of three treatment processes: air etching treatment, acid treatment, and reducing atmosphere treatment, so that the catalyst surface is fully purified, and the post-treated catalyst presents a core-shell structure, the surface of the nanoparticles is wrapped with a uniform layer of platinum skin (shell), and the inside of the nanoparticles is an alloy (core). The post-treated carbon-supported platinum-based catalyst is suitable for ORR reaction in an acidic medium, and the ORR electrocatalytic activity is significantly improved. The catalyst has been successfully applied to the cathode of a proton membrane fuel cell. The results show that the use of a post-treated carbon-supported platinum-based catalyst can greatly improve battery performance, which is of great significance for reducing production costs and promoting large-scale commercial applications of fuel cells.

[0030] An embodiment of the present application provides a post-treatment method for a carbon-supported platinum-based catalyst, which first performs air etching on the carbon-supported platinum-based catalyst to remove carbon deposits on the catalyst surface, and then performs acid treatment and reducing atmosphere treatment to induce the oxidized metal on the catalyst surface to alloy again and form a platinum skin. The catalyst obtained after post-treatment presents a core-shell structure, in which the shell on the surface of the nanoparticles is a platinum skin and the core inside is an alloy.

[0031] In the embodiment of the present application, the alloy is a binary or ternary alloy containing a transition metal, preferably platinum iron, platinum copper, platinum nickel, platinum cobalt or platinum cobalt molybdenum. The carbon carrier of the carbon-supported platinum-based catalyst is nanocarbon black, carbon nanotubes or graphitized carbon black, and the platinum loading is 10-80wt%.

[0032] In the embodiment of the present application, the air etching treatment is to place the carbon-supported platinum-based catalyst in a tubular furnace, heat it at a rate of 2-10°C / min, and treat it at 200-500°C in an air atmosphere for 0.5-4h. Preferably, the catalyst is placed in a quartz crucible.

[0033] Removing carbon deposits through air etching can expose more active sites, that is, platinum and transition metals can be better exposed for subsequent alloying treatment.

[0034] In the embodiment of the present application, the acid treatment is to put the carbon-supported platinum-based catalyst that has been treated with air etching into an acidic solution for ultrasonic dispersion, stir at 50-90°C for 0.5-24h, then add deionized water for washing, filter to obtain a filter cake and dry it. The acidic solution refers to an aqueous solution with an acid concentration of 0.01-1.5 mol / L, and the acid is one or a mixture of nitric acid, sulfuric acid, hydrochloric acid, perchloric acid, and acetic acid, preferably nitric acid or perchloric acid, and the stirring time is preferably 4-16h.

[0035] In the embodiment of the present application, the reducing atmosphere treatment is to grind the catalyst that has been treated with air etching and acid into powder and place it in a reducing atmosphere, heat it to 150-550°C at a rate of 1-15°C / min, and then keep it warm for 0.5-3h. The reducing atmosphere is a hydrogen-argon mixed gas, the volume fraction of hydrogen is 0.5%-15%, and the treatment temperature is preferably 250-500°C.

[0036] The catalyst surface can be fully purified by acid treatment and reducing atmosphere treatment, inducing the oxidized metal on the catalyst surface to alloy again and form a platinum skin, so that the carbon-supported platinum-based catalyst forms a core-shell structure.

[0037] Acid treatment forms a platinum-rich skeleton on the catalyst, but the catalyst surface is uneven and has holes, and the core-shell structure is not completely formed. Reducing atmosphere treatment can further rearrange the atoms on the metal surface, so that a uniform and smooth platinum skin exists on the catalyst surface. In this way, the catalytic activity, stability, mass transfer and conductivity of the catalyst are improved, and the enrichment of platinum on the catalyst surface can reduce the platinum loading and reduce the preparation cost.

[0038] The post-treatment method provided in the embodiment of the present application can process 0.05-1g of carbon-supported platinum-based catalyst in a single batch. The catalyst treated by the post-treatment method provided in the embodiment of the present application can increase the half-wave potential by 12mV in an acidic environment, increase the specific mass activity by 2.1 times, and increase the peak power density by 0.36W cm in actual fuel cell operation. -2 .

[0039] The carbon-supported refractory metal-terminated platinum-cobalt and its preparation method and application provided by the present invention are described below in conjunction with specific embodiments.

[0040] Example 1 This embodiment provides a post-treatment method for a carbon black-supported platinum-cobalt (PtCo / C) catalyst, and the specific steps are as follows: S1, put a small quartz crucible containing 50 mg of PtCo / C catalyst into a tube furnace, heat it to 230° C. at 5° C. / min in an air atmosphere, and keep it warm for 0.5 h to complete the air etching treatment.

[0041] S2, placing the catalyst treated in step S1 into a 0.1M perchloric acid aqueous solution at 60°C, dispersing it evenly with ultrasound, stirring it magnetically and keeping it warm for 10 hours, then washing it with deionized water for 3 times and filtering it with suction, and drying the obtained filter cake in an oven at 60°C to complete the acid treatment.

[0042] S3, the dried solid obtained in step S2 is put into a mortar and ground into powder, and then placed in a small quartz crucible and placed in a hydrogen furnace at 5% H 2The temperature was raised to 400°C at a rate of 10°C / min in a mixed atmosphere of +95% Ar and then kept at that temperature for 2h to complete the reducing atmosphere treatment to obtain a post-treated PtCo / C catalyst.

[0043] X-ray diffraction (XRD) was used to characterize the PtCo / C catalyst before and after treatment. The XRD spectra obtained are shown in Figure 1 As shown in the figure, the treated catalyst showed more significant Pt 3 The unique (110) and (001) superlattice characteristic peaks of Co indicate that a stable long-range ordered atomic arrangement structure, i.e., a platinum-rich structure on the catalyst surface, has been formed after post-treatment. 3 In the ordered structure of Co, the electronic effect of Co can further optimize the electronic state of Pt through the long-range ordered structure, making the d-band center closer to the ideal position, thereby improving the catalytic activity.

[0044] Transmission electron microscopy (TEM) was used to characterize the PtCo / C catalyst before and after treatment. The TEM images are shown in Figure 2 As shown, it can be seen that the post-treatment did not change the particle size of the nanoparticles or cause agglomeration. The dark platinum-cobalt nanoparticles were evenly distributed on the carbon support, and the particle size of the nanoparticles before and after treatment was similar.

[0045] See also Figure 3 As shown, the left figure (A) shows the ordered L1 of metal nanoparticles in the treated PtCo / C catalyst 2 Superlattice structure, the right picture (B) is the HAADF-STEM image of the treated PtCo / C catalyst product. It can be seen that platinum atoms occupy the face-centered position of the cubic lattice, and cobalt atoms are regularly distributed at the top corners (as shown by the atomic-level contrast lines). On the one hand, this long-range ordered atomic arrangement can significantly optimize the electronic structure of platinum through the ligand effect: the electron extraction effect of cobalt atoms on platinum can weaken the adsorption strength of oxygen intermediates (*O, *OH), thereby reducing the activation energy of the rate-determining step (OO bond cleavage) of the oxygen reduction reaction. On the other hand, the platinum skin structure with a surface thickness of about 0.6nm (3-4 atomic layers of the surface without cobalt exposure) can improve the catalytic stability through dual mechanisms: (1) The geometric effect inhibits the dissolution of cobalt in an acidic environment and avoids the collapse of active sites; (2) The strong interaction between the surface platinum atoms and the carrier carbon can effectively anchor the nanoparticles and inhibit Ostwald ripening under high temperature and high pressure conditions. This "core-shell synergistic" structure can effectively improve the activity of fuel cells and extend battery life.

[0046] Example 2 Example 2 provides a post-treatment method for a carbon black-supported platinum copper (PtCu / C) catalyst, the specific steps of which are as follows: S1, placing a small quartz crucible containing 50 mg of PtCu / C catalyst into a tube furnace, heating to 230° C. at 5° C. / min in an air atmosphere, and keeping the temperature for 0.5 h to complete the air etching treatment.

[0047] S2, placing the catalyst treated in step S1 into a 0.1M perchloric acid aqueous solution at 60°C, dispersing it evenly with ultrasound, stirring it magnetically and keeping it warm for 10 hours, then washing it with deionized water for 3 times and filtering it, and placing the obtained filter cake in an oven and drying it at 60°C to complete the acid treatment.

[0048] S3, the dried solid obtained in step S2 is put into a mortar and ground into powder, and then placed in a small quartz crucible and placed in a hydrogen furnace at 5% H 2 The temperature was raised to 400°C at a rate of 10°C / min in a mixed atmosphere of +95% Ar and then kept at that temperature for 2h to complete the reducing atmosphere treatment to obtain a post-treated PtCo / C catalyst.

[0049] Example 3 Example 3 provides a post-treatment method for a carbon black-supported platinum-cobalt-copper (PtCoCu / C) catalyst, the specific steps of which are as follows: S1, placing a small quartz crucible containing 50 mg of PtCoCu / C catalyst into a tube furnace, heating to 230° C. at 5° C. / min in an air atmosphere, and keeping the temperature for 0.5 h to complete the air etching treatment.

[0050] S2, placing the catalyst treated in step S1 into a 0.1M perchloric acid aqueous solution at 60°C, dispersing it evenly with ultrasound, stirring it magnetically and keeping it warm for 10 hours, then washing it with deionized water for 3 times and filtering it with suction, and drying the obtained filter cake in an oven at 60°C to complete the acid treatment.

[0051] S3, the dried solid obtained in step S2 is put into a mortar and ground into powder, and then placed in a small quartz crucible and placed in a hydrogen furnace at 5% H 2 The temperature was raised to 400°C at a rate of 10°C / min in a mixed atmosphere of +95% Ar and then kept at that temperature for 2h to complete the reducing atmosphere treatment to obtain a post-treated PtCo / C catalyst.

[0052] Comparative Example 1 Comparative Example 1 provides a post-treatment method for a graphitized carbon black-supported platinum-cobalt (PtCo / C) catalyst. The difference between Comparative Example 1 and Example 1 is that only air etching treatment is performed, that is, only step S1 is included, and steps S2-S3 are omitted. The other contents are substantially the same as those in Example 1 and will not be repeated here.

[0053] Comparative Example 2 Comparative Example 2 provides a post-treatment method for a graphitized carbon black-supported platinum-cobalt (PtCo / C) catalyst, which only performs air etching treatment and reducing atmosphere treatment, that is, only includes steps S1 and S3, without step S2, and the other contents are substantially the same as those in Example 1, which will not be repeated here.

[0054] The rotating disk polarization curves of commercial platinum-carbon (Pt / C) catalyst (Johnson Matthey, 20%wt. platinum), catalysts of Examples 1-3 and Comparative Examples 1-2 in acid medium were tested respectively. 2 ) saturated 0.1M HClO 4 , the scanning rate was 10 mV / s, the scanning voltage range was 0.05-0.1 V (vs. RHE), and the rotation speed was rpm=1600.

[0055] See also Figure 4 As shown, it is a comparison diagram of the rotating disk polarization curves of the commercial Pt / C catalyst, Example 1 and Comparative Examples 1-2 in an acid medium (polarization curve after iR compensation). Among them, the half-wave potential of the catalyst obtained after treatment is sorted from large to small as follows: Example 1 after treatment> Comparative Example 2 after treatment> Comparative Example 1 after treatment> Commercial Pt / C. The catalyst of Example 1 is post-treated, and the half-wave potential is increased by 12mV. The treated sample in Comparative Example 1 is reduced by 5mV relative to the half-wave potential before treatment, and the treated sample in Comparative Example 2 has no significant change relative to the half-wave potential before treatment. This is because, Comparative Example 1 does not perform step S2-S3 treatment, the catalyst surface fails to be fully purified, and the oxidized metal on the catalyst surface fails to be induced to alloy again and form a platinum skin, so that the carbon-supported platinum-based catalyst fails to form a complete core-shell structure, resulting in its performance not being able to be better improved. The platinum-based catalyst that is not acid-washed in Comparative Example 2 will have problems such as residual impurities, metal poisoning, poor interface contact and microstructural defects, resulting in its performance not being able to be better improved after hydrogen calcination.

[0056] See also Figure 5 The figure shows the comparison of the rotating disk polarization curves in acid medium of the commercial Pt / C catalyst and the catalyst of Example 2. The half-wave potential of the catalyst obtained after the treatment of Example 2 is increased by 9 mV compared with that before the treatment.

[0057] See also Figure 6 The figure shows the comparison of the rotating disk polarization curves in acid medium of the commercial Pt / C catalyst and the catalyst of Example 3. The half-wave potential of the catalyst obtained after the treatment of Example 3 is increased by 4 mV compared with that before the treatment.

[0058] In nitrogen (N 2 ) saturated 0.1M HClO 4In the experiment, the commercial Pt / C catalyst and the catalysts of Examples 1-3 were subjected to cyclic voltammetry (CV) tests at 0.05-0.1 V (vs. RHE) at a scan rate of 50 mA / s to calculate the electrochemically active surface area (ECSA). The CV curves of the catalysts in the acid medium obtained by the test are shown in FIG. Figures 7 to 9 It can be seen that the hydrogen adsorption / desorption peak area of ​​the catalyst obtained by post-treatment is significantly increased compared with that before treatment and the commercial Pt / C catalyst, indicating that after post-treatment, the number of platinum atoms participating in the electrocatalytic reaction in the carbon-supported platinum-based catalyst is significantly increased.

[0059] use Figure 4 The platinum mass specific activity obtained by normalizing the current value at 0.9 V of the polarization curve by the platinum loading is Figure 7 The electrochemical active area of ​​the catalyst in Example 1 before and after treatment was calculated by calculating the hydrogen adsorption / desorption peak area in Fig.10 The mass specific activity of the catalyst obtained after treatment increased from 0.56A mg Pt -1 Increased to 1.19A mg Pt -1 , which is 2.1 times higher than that before treatment and 10 times higher than that of commercial Pt / C catalyst; the electrochemical active area of ​​the catalyst after treatment is increased from 25.1m 2 g Pt -1 Increased to 74.6m 2 g Pt -1 , which is 2.97 times higher than that of commercial Pt / C catalyst.

[0060] Application Example 1 Application Example 1 provides an application of the post-treated PtCo / C catalyst in Example 1 in a hydrogen-oxygen fuel cell. The specific steps are: dispersing catalyst powder (the catalyst powder is a post-treated PtCo / C catalyst or a commercial Pt / C catalyst with a platinum loading of 60 wt%) and 5 wt% Nafion solution into isopropanol-water (V 异丙醇 :V 水 =9:1) mixed solvent to obtain a mixture, and then the mixture was placed in ice water for ultrasonic treatment for more than 1 hour, and after uniform dispersion, a catalytic ink was obtained. The prepared catalytic ink was sprayed onto a Nafion membrane (Nafion NC700) with a thickness of 15 μm using a pneumatic spray pen, and heated at 80°C to evaporate the solvent to obtain an effective area of ​​5 cm 2 The catalyst coated membrane (CCM) was prepared by post-treatment of the homemade PtCo / C catalyst for the cathode side, with a cathode platinum loading of 0.3 mg / cm 2; A commercial Pt / C catalyst with a Pt loading of 60 wt% was used on the anode side, and the anode Pt loading was 0.2 mg / cm 2 The thickness of the carbon paper was 235 μm. Thus, a complete membrane electrode (MEA) was obtained. Finally, a single cell test was performed using a fuel cell test equipment (Scribner 850e). The cell temperature was maintained at 80 °C, the relative humidity was 100%, and the back pressure was set to 2 bar. 2 / O 2 Flow rate: 0.5 / 2 L min -1 The steady-state polarization curves were collected under the conditions and the power density curves were calculated.

[0061] Application Example 2 The difference between Application Example 2 and Application Example 1 is that the PtCo / C catalyst that has not been post-treated is used in a hydrogen-oxygen fuel cell. The rest is the same as Application Example 1 and will not be described again.

[0062] The comparison of the polarization curve and power density curve of the catalyst in the hydrogen-oxygen fuel cell is shown in Fig.11 As shown in Figure 2, the peak power density of the fuel cell reached 1.70 W cm when the post-treated catalyst was used as the cathode of the fuel cell. -2 , which is 0.36 W cm- -2 , indicating that after using the post-treated catalyst, the peak power density of the fuel cell is significantly increased. This can greatly improve the output capacity and energy conversion efficiency of the fuel cell, extend the service life of the battery, and effectively reduce production costs.

[0063] In summary, the present application provides a post-treatment method for a carbon-supported platinum-based catalyst, which first performs air etching on the carbon-supported platinum-based catalyst to remove carbon deposits on the catalyst surface, and then performs acid treatment and reducing atmosphere treatment to induce the oxidized metal on the catalyst surface to alloy again and form a platinum skin. The catalyst obtained after post-treatment presents a core-shell structure, in which the shell on the surface of the nanoparticles is a platinum skin and the core inside is an alloy. After post-treatment, the half-wave potential of the PtCo / C catalyst in Example 1 in an acidic environment is increased by 12mV, the specific mass activity is increased by 2.1 times, and the peak power density is increased by 0.36W cm in actual fuel cell operation. -2 .

[0064] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A post-treatment method for a carbon-supported platinum-based catalyst, characterized in that: The carbon-supported platinum-based catalyst is first subjected to air etching treatment to remove carbon deposits on the catalyst surface, and then subjected to acid treatment and reducing atmosphere treatment to induce the oxidized metal on the catalyst surface to alloy again and form a platinum skin. The catalyst obtained after post-treatment presents a core-shell structure, wherein the shell on the surface of the nanoparticle is a platinum skin and the core inside is an alloy; the alloy is a binary or ternary alloy containing a transition metal; and the platinum loading in the carbon-supported platinum-based catalyst is 10-80wt%.

2. The post-treatment method of the carbon-supported platinum-based catalyst according to claim 1, characterized in that: The carbon carrier of the carbon-supported platinum-based catalyst is nanocarbon black, carbon nanotube or graphitized carbon black.

3. The post-treatment method of the carbon-supported platinum-based catalyst according to claim 1, characterized in that: The alloy contains one or two of platinum, manganese, iron, copper, nickel, zinc, cobalt and molybdenum.

4. The post-treatment method of the carbon-supported platinum-based catalyst according to claim 1, characterized in that: The air etching treatment refers to placing the carbon-supported platinum-based catalyst in an air atmosphere at 200-500° C. for 0.5-4 hours.

5. The post-treatment method of the carbon-supported platinum-based catalyst according to claim 1, characterized in that: The acid treatment refers to placing the carbon-supported platinum-based catalyst that has been treated with air etching into an acidic solution for uniform ultrasonic dispersion, stirring at 50-90° C. for 0.5-24 hours, then adding deionized water for washing, filtering to obtain a filter cake and drying it.

6. The post-treatment method of the carbon-supported platinum-based catalyst according to claim 1, characterized in that: The reducing atmosphere treatment refers to grinding the catalyst treated with air etching and acid into powder and placing it in a reducing atmosphere, heating it to 150-550° C. at a rate of 1-15° C. / min, and then keeping it warm for 0.5-3 hours.

7. The post-treatment method of the carbon-supported platinum-based catalyst according to claim 4, characterized in that: The equipment used for the air etching is a tube furnace.

8. The post-treatment method of the carbon-supported platinum-based catalyst according to claim 5, characterized in that: The acidic solution refers to an aqueous solution with an acid concentration of 0.01-1.5 mol / L, wherein the acid is one or more of nitric acid, sulfuric acid, hydrochloric acid, perchloric acid, and acetic acid.

9. The post-treatment method of the carbon-supported platinum-based catalyst according to claim 8, characterized in that: In the acid treatment, nitric acid or perchloric acid is used as the acid, and the stirring time is 4-16 hours.

10. The post-treatment method of carbon-supported platinum-based catalyst according to claim 6, characterized in that: The reducing atmosphere is a hydrogen-argon mixed gas, wherein the volume fraction of hydrogen is 0.5%-15%.

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