Carbon carrier material for microwave-assisted phosphoric acid treatment oxygen reduction, catalyst, preparation method and application thereof

Abstract

The invention relates to a carbon carrier material for microwave-assisted phosphoric acid treatment and oxygen reduction, a catalyst, a preparation method and application thereof, and the scheme is innovated by the following steps: dipping conductive carbon black (such as ketjen black ECP600JD) and 60-70wt% phosphoric acid solution according to a solid-to-liquid ratio of 1g / (15-18) mL, preheating at 100-250 DEG C in an argon atmosphere, then carrying out a reaction for 10-100 seconds under the assistance of a microwave power of 100-600 W, and carrying out vacuum drying to obtain the carbon carrier material for microwave-assisted phosphoric acid treatment and oxygen reduction. The phosphorus content of the prepared carbon carrier material is 4-6wt%, and the graphitization degree of the carbon carrier material is improved (ID / IG value is 1.15-1.20). And after the platinum-cobalt alloy is further loaded, the particle size of the nanoparticles is uniform, the potential loss is only 3 mV after 5000 accelerated attenuation tests in the proton exchange membrane fuel cell, and the power density attenuation is reduced by 58%. The method has the advantages of quick reaction, low energy consumption, high corrosion resistance and the like, and the stability of the catalyst is remarkably improved.

Description

Technical Field

[0001] The present application relates to the field of fuel cell catalysts, and specifically relates to a carbon support material, a catalyst, a preparation method and an application thereof for microwave-assisted phosphoric acid treatment of oxygen reduction, which are used to improve the stability and corrosion resistance of proton exchange membrane fuel cell (PEMFC) catalysts. Background Art

[0002] Proton exchange membrane fuel cells (PEMFCs) have important application values in the fields of energy transportation, aerospace, etc. due to their advantages such as environmental friendliness and high fuel utilization efficiency. As the core component of PEMFCs, the performance of catalysts is directly affected by the carbon support material. Carbon materials have become common carriers due to their high electrical conductivity and pore structure. However, they are easily corroded in extreme environments such as strong acidity and high potential, resulting in a decrease in the activity of catalysts. The traditional high-temperature calcination method for treating carbon supports has defects such as long treatment time, uneven heating, and insufficient corrosion resistance. Although phosphorus doping can improve the electrical conductivity and corrosion resistance of carbon supports, traditional methods (such as high-temperature calcination) still have problems of uneven treatment and low efficiency, and it is difficult to meet the strict requirements of fuel cells for stability.

[0003] Therefore, it is of great research significance and application value to develop a carbon support material, a catalyst, a preparation method and an application thereof for microwave-assisted phosphoric acid treatment of oxygen reduction, which are used to solve the defects of long treatment time, uneven heating, and insufficient corrosion resistance of carbon supports in the traditional high-temperature calcination method and phosphorus treatment technology, resulting in problems such as a decrease in the stability and activity of catalysts. Summary of the Invention

[0004] The purpose of the present application is to address the above problems existing in the prior art, and provide a carbon support material, a catalyst, a preparation method and an application thereof for microwave-assisted phosphoric acid treatment of oxygen reduction. By microwave-assisted phosphoric acid treatment of the carbon support material, the efficient doping of phosphorus atoms and the improvement of the graphitization degree of the carbon support are realized by using the rapid and uniform heating and non-thermal effect of microwaves, thereby enhancing the corrosion resistance of the carbon support and the stability of the catalyst.

[0005] In order to achieve the above application purpose, the present application adopts the following technical solutions: A carbon support material for microwave-assisted phosphoric acid treatment of oxygen reduction, the carbon support material contains carbon and phosphorus elements, and the weight percentage of the phosphorus element is 4-6 wt%; The I D / I G value of the Raman spectrum of the carbon support material is 1.15-1.20, indicating an improvement in the graphitization degree; The carbon support material is mainly mesoporous, with a specific surface area of 500-600 m 2 / g, and the micropore pore volume ≤ 0.02 cm 3 / g.

[0006] Further, the carbon support material is prepared by microwave-assisted phosphoric acid treatment of conductive carbon black, and the conductive carbon black is one of Ketjen black ECP300J, Ketjen black ECP600JD, XC72R or CABOT BP2000.

[0007] A preparation method of the carbon support material for microwave-assisted phosphoric acid treatment of oxygen reduction as described above, comprising the following steps: S1. Mix and impregnate the conductive carbon black with a phosphoric acid solution to obtain a pretreated material; S2. Perform microwave irradiation treatment on the pretreated material under an inert atmosphere to obtain a phosphorus-doped carbon support material.

[0008] Further, in step S1, the conductive carbon black is evenly placed in a quartz boat, and 60-70 wt% H 3 PO 4 solution is added dropwise, controlling the solid-liquid ratio to be 1 g / (15-18) mL, and impregnating for 1-2 h.

[0009] Further, in step S1, the impregnated material is transferred to a tubular furnace, heated to 100-250 °C at a heating rate of 5 °C / min in an argon atmosphere, held for 1-3 h, and naturally cooled.

[0010] Further, in step S2, the pretreated material is transferred to a microwave reaction vessel, treated at a microwave power of 100-600 W for 10-100 s under an argon flow rate of 300-500 SCCM; after cooling to room temperature, it is washed with pure water until neutral, filtered by suction, dried under vacuum and ground to obtain the carbon support material.

[0011] A catalyst based on the carbon support material for microwave-assisted phosphoric acid treatment of oxygen reduction as described above, the catalyst comprising the above carbon support material, platinum and cobalt, wherein the mass ratio of the carbon support material, platinum acetylacetonate and cobalt acetylacetonate is 5:4:4, and the particle size of the platinum-cobalt alloy nanoparticles is 2.5-3.5 nm.

[0012] Further, preparation of the precursor: Dissolve the carbon support material, platinum acetylacetonate and cobalt acetylacetonate in acetone, and perform rotary evaporation at 50-60 °C and 80-100 r / min for 0.5-1 h to obtain a precursor powder; High-temperature thermal reduction: Place the precursor powder in a tubular furnace, and heat it to 800-900 °C at a heating rate of 5 °C / min in a hydrogen / argon mixed gas atmosphere, and hold for 1 h; Annealing treatment: Cool down to 600-700 °C at a cooling rate of 5 °C / min, and hold for 5-6 h to obtain the catalyst.

[0013] Further, the volume ratio of hydrogen to argon in the hydrogen / argon mixed gas is 1:9.

[0014] The application of the above catalyst, where the catalyst is used in a proton exchange membrane fuel cell.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. Significantly improved efficiency: The microwave-assisted treatment time is short (seconds to minutes), the heating is uniform, and the energy consumption is lower than that of the traditional high-temperature calcination method.

[0016] 2. Optimized structural performance: The phosphorus doping is uniform (P content 5.63 wt%), the graphitization degree of the carbon support is increased (the I D / I G value drops from 1.25 to 1.20), the surface defects are reduced, and the corrosion resistance is significantly enhanced (the oxidation current density is reduced and the cumulative oxidation charge is decreased).

[0017] 3. Enhanced catalytic performance: The particle size of the supported PtCo alloy nanoparticles is more uniform (3 nm vs 4 nm), without agglomeration. When used as a catalyst in a proton exchange membrane fuel cell, the rated power density is significantly increased. After 5000 cycles of accelerated degradation testing, the potential loss and power density loss are small, showing high catalytic activity and stability.

[0018] 4. Strong process applicability: Low cost, simple operation, suitable for industrial production, and can be extended to other carbon materials (such as the carbon support materials C72R and BP2000 for microwave-assisted phosphoric acid treatment of oxygen reduction) and catalyst systems (such as PtFe and PtNi alloys). Description of the Drawings

[0019] Figure 1 is the P 2 p spectrum of P-ECP600JD-MW according to Example 1 of the present invention and ECP600JD of Comparative Example 1; Figure 2 is the Raman spectrum of P-ECP600JD-MW according to Example 1 of the present invention and ECP600JD of Comparative Example 1; Figure 3 is the LSV (linear sweep voltammetry) graph of P-ECP600JD-MW according to Example 1 of the present invention and ECP600JD of Comparative Example 1; Figure 4 is the graph of the change in the cumulative oxidation charge during the 50-cycle cyclic voltammetry test of P-ECP600JD-MW according to Example 1 of the present invention and ECP600JD of Comparative Example 1; Figure 5 is the N 2 adsorption / desorption isotherm graph of P-ECP600JD-MW according to Example 1 of the present invention and ECP600JD of Comparative Example 1; Figure 6 is the pore size distribution diagram obtained from the desorption curve of P-ECP600JD-MW according to Embodiment 1 of the present invention and ECP600JD of Comparative Example 1; Figure 7 is the TEM image and particle size distribution diagram of P-EC600-PtCo according to Embodiment 2 of the present invention; Figure 8 is the diagram of the change in potential and power density of P-EC600-PtCo according to Embodiment 2 of the present invention before and after the accelerated degradation test; Figure 9 is the TEM image and its particle size distribution diagram of EC600-PtCo of Comparative Example 2 of the present invention; Figure 10 is the comparison diagram of the change in potential and power density of P-EC600-PtCo according to Embodiment 2 of the present invention and EC600-PtCo of Comparative Example 2 before the accelerated degradation test; Figure 11 is the diagram of the change in potential and power density of EC600-PtCo of Comparative Example 2 of the present invention before and after the accelerated degradation test. Detailed implementation manners

[0020] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application belong to the scope of protection of the present application.

[0021] Embodiment 1 The preparation method of the carbon carrier material for oxygen reduction treated by microwave-assisted phosphoric acid includes the following steps: Step 1: Place the carbon black evenly in a quartz boat, and dropwise add H 3 PO 4 solution, impregnate for a period of time, place it in a tube furnace, heat at a certain heating rate to reach the temperature condition for a certain time, and then cool naturally.

[0022] In Step 1, the conductive carbon black is Ketjenblack ECP300J, Ketjenblack ECP600JD, XC72R, or CABOT BP2000, etc. In this patent, Ketjenblack ECP600JD is taken as an example.

[0023] In Step 1, the weight percentage of the H 3 PO 4 solution is 60-70 wt%, and the solid-liquid ratio of the mixture of ECP600JD and H 3 PO 4 solution is 1 g / 17 mL.

[0024] In Step 1, the impregnation time of carbon black with the H 3 PO 4 solution is 1 - 2 h.

[0025] In Step 1, the impregnated material is placed in a reactor. Under argon conditions, the heating rate in a sand bath is 5 °C / min, and it is heated to 100 - 250 °C and allowed to evaporate naturally. The heating time at 100 - 250 °C is 1 - 3 h.

[0026] Step 2: Transfer the prepared material to a microwave reaction vessel and react under an argon atmosphere and a certain microwave power. After rapid microwave reaction, it is cooled to room temperature. Add pure water to wash until neutral, and then perform suction filtration. After vacuum drying, it is ground and stored to obtain P - ECP600JD - MW.

[0027] In Step 2, the argon flow rate during microwave reaction is 300 - 500 SCCM.

[0028] In Step 2, the set power during microwave reaction is 100 - 600 W, and the microwave reaction time is 10 - 100 s.

[0029] In order to verify whether the carbon support material of Example 1 (such as P - ECP600JD - MW) is successfully doped with phosphorus (P) element after microwave - assisted phosphoric acid treatment and determine its elemental composition ratio. In this example, EDS (a technique for qualitative and quantitative analysis of elements by detecting the energy and intensity of characteristic X - rays generated when a sample is excited by an electron beam) is used for analysis. Table 1 is the quantitative table of each element of P - ECP600JD - MW analyzed by EDS energy spectrum, where the weight percentage of C is 94.37 wt%, and the weight percentage of P is 5.63 wt%, indicating that P atoms are incorporated into the carbon support after microwave - assisted phosphoric acid treatment.

[0030] Table 1

[0031] It can be seen that Table 1 provides qualitative and quantitative evidence of phosphorus doping through EDS analysis.

[0032] Preferably, in order to further confirm the incorporation of P and study the structural state, XPS analysis (an analytical technique for determining the chemical state and electronic structure of elements by measuring the energy of photoelectrons emitted when surface atoms of a sample are excited by X - rays) is performed on P - ECP600JD - MW. Figure 1 For the P 2 of P - ECP600JD - MW in Example 1 and ECP600JD in Comparative Example 1 p spectra, from Figure 1It can be seen that the C—P peak appears at the binding energy of 133.8 eV in P-ECP600JD-MW, proving that the P atoms are successfully doped into the carbon support after microwave-assisted phosphoric acid treatment.

[0033] Preferably, in order to further analyze the characteristic changes of P-ECP600JD-MW, Figure 2 are the Raman spectra of P-ECP600JD-MW in Example 1 and ECP600JD in Comparative Example 1. The D peak and G peak appear at about 1338 cm -1 and 1580 cm -1 respectively. The I D / I G value of P-ECP600JD-MW is 1.20.

[0034] In order to evaluate the corrosion resistance of P-ECP600JD-MW in a strong oxidation environment, linear voltammetry tests were carried out. Figure 3 are the LSV (linear sweep voltammetry, potential range 1.0 - 1.5 V simulating the high potential working conditions of a proton exchange membrane fuel cell (PEMFC), the lower the oxidation current density, the less easily the material is oxidized) diagrams of P-ECP600JD-MW in Example 1 and ECP600JD in Comparative Example 1. The potential range of the linear sweep voltammetry test is 1.0 - 1.5 V and the scan rate is 1 mV / s. It can be seen from Figure 3 that P-ECP600JD-MW shows a lower oxidation current density.

[0035] Figure 4 are the diagrams of the change in the cumulative oxidation charge of P-ECP600JD-MW in Example 1 and ECP600JD in Comparative Example 1 during 50 cyclic voltammetry tests. The potential range of the cyclic voltammetry test is 1.0 - 1.5 V and the scan rate is 50 mV / s. The charge in the figure is obtained by integrating the oxidation peak of the cyclic voltammetry curve and calculating the cumulative oxidation charge at 1.25 V to describe the cumulative charge amount of the carbon support during the electrooxidation process. It can be seen from Figure 4 that the cumulative oxidation charge of P-ECP600JD-MW is lower.

[0036] In order to further explore the pore structure of the carbon support material and the microwave treatment mechanism, and to elaborate on the change in the pore structure of the carbon support and its influence on the performance, the following content is presented: Figure 5 and Figure 6 respectively show the N 2 adsorption / desorption isotherms and the pore size distribution diagrams obtained from the desorption curves of P-ECP600JD-MW in Example 1 and ECP600JD in Comparative Example 1. According to the classification of IUPAC, Figure 5The adsorption and desorption isotherm presents a Langmuir type Ⅳ, and an obvious hysteresis loop appears in the relative pressure range of P / P 0 from 0.4 to 1.0, which is caused by the capillary effect leading to the condensation of nitrogen in the mesopores, indicating that P-ECP600JD-MW has a uniform mesoporous structure. Table 2 shows the pore structure parameters of the samples. The specific surface area of P-ECP600JD-MW is 583.7 m 2 / g, the micropore volume is 0.016 cm 3 / g, and the mesopore volume is 1.6 cm 3 / g. Figure 6 It shows that the number of micropores is small after microwave-assisted phosphoric acid treatment, indicating that the micropores have collapsed.

[0037] Table 2

[0038] Among them, the specific surface area is calculated by the nitrogen adsorption method (BET theory), which reflects the total surface area of the material (including micropores, mesopores, and macropores). The micropore volume (pore diameter < 2nm) is calculated by the HK method or the t-plot method, which reflects the proportion of the micropore volume. The mesopore volume (pore diameter 2 - 50nm) is calculated by the BJH method (desorption curve), which reflects the proportion of the mesopore volume.

[0039] Comparative Example 1 A preparation method of a carbon support material without microwave-assisted phosphoric acid treatment for oxygen reduction. The conductive carbon black used is the same as that in Example 1. The difference is that the phosphoric acid impregnation and microwave reaction in Steps 1 and 2 are not carried out, that is, the pure ECP600JD without microwave-assisted phosphoric acid treatment is obtained. The material obtained in Comparative Example 1 is simply referred to as "ECP600JD".

[0040] Preferably, in order to confirm that the ECP600JD in Comparative Example 1 does not contain P itself, XPS analysis (an analytical technique that determines the chemical state and electronic structure of elements by measuring the energy of photoelectrons emitted when atoms on the sample surface are excited by X-rays) was carried out on ECP600JD. Figure 1 For the P 2 p spectrograms of P-ECP600JD-MW in Example 1 and ECP600JD in Comparative Example 1, it can be seen from Figure 1 that there are obviously no peaks related to the P structure on the curve of ECP600JD, indicating that ECP600JD itself does not contain P, further proving that the carbon support after microwave-assisted phosphoric acid treatment has successfully doped P atoms.

[0041] Combining the results of Example 1 and Comparative Example 1, it can be seen that during the process of microwave-assisted phosphoric acid treatment of the oxygen reduction carbon support material, microwave energy realizes rapid bulk heating through dielectric loss and ionic conduction, prompting the decomposition of phosphoric acid to release active phosphorus substances. The microwave non-thermal effect can reduce the doping energy barrier of phosphorus atoms and promote the bonding of phosphorus atoms with carbon defect sites. This indicates that microwave-assisted phosphoric acid treatment of the oxygen reduction carbon support material introduces controllable phosphorus doping sites.

[0042] Preferably, in order to further analyze the characteristic changes of ECP600JD obtained in Comparative Example 1, Figure 2 are the Raman spectra of P-ECP600JD-MW in Example 1 and ECP600JD in Comparative Example 1. The D peak and G peak appear at 1338 cm -1 and 1580 cm -1 respectively. The I D / I G value of ECP600JD is 1.25. Comparing with the I D / I G value of 1.20 of P-ECP600JD-MW in Example 1, it can be seen that after microwave-assisted phosphoric acid treatment, the I D / I G value decreases, indicating that the graphitization degree of the carbon support material after treatment has been improved to a certain extent and the surface defects are reduced.

[0043] In order to evaluate the corrosion resistance of ECP600JD in a strong oxidation environment, linear voltammetry tests were carried out. Figure 3 are the LSV (linear sweep voltammetry) diagrams of P-ECP600JD-MW in Example 1 and ECP600JD in Comparative Example 1. The potential range of the linear sweep voltammetry test is 1.0 - 1.5 V and the scan rate is 1 mV / s. As can be seen from Figure 3 , ECP600JD shows a higher oxidation current density than P-ECP600JD-MW. Combining with the LSV analysis results of Example 1, it shows that P-ECP600JD-MW is less likely to be oxidized, thus improving its corrosion resistance.

[0044] Figure 4Charge change diagram of cumulative oxidation charge during 50 - cycle voltammetry test for P - ECP600JD - MW in Example 1 and ECP600JD in Comparative Example 1. The potential range of the cyclic voltammetry test is 1.0 - 1.5 V, and the scanning rate is 50 mV / s. The charge in the figure is obtained by integrating the oxidation peak of the cyclic voltammetry curve and calculating the cumulative oxidation charge at 1.25 V to describe the cumulative charge amount of the carbon support during the electro - oxidation process. By comparing with the cumulative oxidation charge of Example 1, it can be seen that the cumulative oxidation charge of P - ECP600JD in Example 1 is significantly lower than that of ECP600JD in Comparative Example 1, indicating that microwave - assisted phosphoric acid treatment significantly reduces the degree of oxidative corrosion of the carbon support.

[0045] In summary, combined with the EDS energy spectrum analysis results in Table 1, during the process of microwave - assisted phosphoric acid treatment of oxygen - reduction carbon support materials, the phosphorus atoms generated by the promotion of decomposition in the microwave reaction bond with the carbon defect sites while enhancing the graphitization degree of the carbon support, optimizing the structure and performance of the carbon support.

[0046] In order to further explore the pore structure and microwave treatment mechanism of the carbon support material, and to elaborate on the changes in the pore structure of the carbon support and its influence on performance, the following content is proposed: Figure 5 and Figure 6 respectively show the N 2 adsorption / desorption isotherms and pore size distribution diagrams obtained from the desorption curves of the carbon materials of Example 1 and Comparative Example 1. According to the IUPAC classification, Figure 5 the adsorption - desorption isotherm shows a Langmuir type Ⅳ, with an obvious hysteresis loop appearing in the relative pressure range of P / P 0 from 0.4 to 1.0, which is caused by the capillary effect resulting in the condensation of nitrogen in the mesopores, indicating that ECP600JD has a uniform mesoporous structure. Table 2 shows the pore structure parameters of the samples. By comparing with the pore structure parameters of Example 1, it can be seen that the specific surface area decreases from 1337.1 m 2 / g to 583.7 m 2 / g after microwave - assisted phosphoric acid treatment, and the micropore volume decreases from 0.035 cm 3 / g to 0.016 cm 3 / g. Figure 6 This further confirms the reduction in the number of micropores after microwave - assisted phosphoric acid treatment, and the collapse of micropores. Combining the results of Raman spectra, LSV diagrams, and oxidation charge quantity changes of Example 1 and Comparative Example 1, microwave - assisted phosphoric acid treatment effectively reduces the surface defects of the carbon material, improving the densification and corrosion resistance of the material.

[0047] Example 2 Based on Example 1, the catalyst was further prepared on the basis of Example 1, specifically including the following steps: Step 3: Carbon black (the carbon support material of Example 1, such as P-ECP600JD-MW), platinum acetylacetonate, and cobalt acetylacetonate were placed in acetone and mixed evenly to obtain a precursor solution. Then, the precursor solution was rotary evaporated to obtain a precursor powder. Then, under certain conditions, the precursor powder was placed in a tubular furnace for high-temperature thermal reduction, and finally, after cooling to the annealing temperature, annealing treatment was carried out to obtain an alloy catalyst based on a microwave-assisted phosphoric acid-treated carbon support, abbreviated as P-EC600-PtCo; In Step 3, the conductive carbon black was P-ECP600JD-MW; In Step 3, the mass ratio of conductive carbon black, platinum acetylacetonate, and cobalt acetylacetonate was 5:4:4; In Step 3, the conditions for rotary evaporation of the precursor solution were: at a rotation speed of 80 - 100 r / min, and a rotary evaporation time of 0.5 - 1 h at 50 - 60 °C; In Step 3, the conditions for high-temperature thermal reduction in the tubular furnace were: under a mixed gas condition, the heating rate was 5 °C / min, heated to 800 - 900 °C, and the heating time at 800 - 900 °C was 1 h; In Step 3, the conditions for annealing treatment in the tubular furnace were: under a mixed gas condition, the cooling rate was 5 °C / min, cooled to 600 - 700 °C, and the annealing time at 600 - 700 °C was 5 - 6 h; In Step 3, the mixed gas was a mixed gas of hydrogen and argon, and the volume ratio of hydrogen to argon was 1:9.

[0048] In order to characterize the microscopic morphology of P-EC600-PtCo, transmission electron microscopy (TEM) tests were carried out, Figure 7 Figure 19 is the TEM image of P-EC600-PtCo and its particle size distribution diagram (inset). Figure 7 It shows that the alloy nanoparticles in the P-EC600-PtCo catalyst are evenly distributed, without obvious agglomeration, and the particle size is stable at about 3 nm.

[0049] In order to further verify the durability and stability of P-EC600-PtCo, performance tests under a membrane electrode assembly (MEA) were carried out, that is, used in a proton exchange membrane fuel cell and then performance tests were carried out. Figure 8 、 10 Figures 28 and 11 show the fuel cell performance and the performance before and after 5000 cycles of accelerated degradation (test potential 0.6 - 1.2 V) tests.

[0050] Figure 8Figure showing the changes in potential and power density of P-EC600-PtCo before and after the accelerated degradation test. As shown by Figure 8 and Table 3 (Summary table of potential losses of fuel cells before and after the accelerated degradation test), at a current density of 0.8 mA / cm 2 , the potential of P-EC600-PtCo is 722 mV. After 5000 cycles of accelerated degradation test, the potential is 719 mV, only decreasing by 3 mV.

[0051] Table 3

[0052] As shown by Figure 8 and Table 4 (Summary table of rated power density losses of fuel cells before and after the accelerated degradation test), at a voltage of 0.67 V, the rated power density of P-EC600-PtCo is 857 mW / cm 2 . After 5000 cycles of accelerated degradation test, the rated power density is 789 mW / cm 2 , with a decrease of 68 mW / cm 2 .

[0053] Table 4

[0054] Based on the above test results, it can be seen that the platinum-cobalt catalyst with ECP600JD treated by microwave-assisted phosphoric acid as the carrier has high catalytic activity and stability.

[0055] Comparative Example 2 Based on Comparative Example 1, a catalyst was prepared on the basis of Comparative Example 1. The steps for preparing the catalyst were the same as those in Example 2, except that: the conductive carbon black used was ECP600JD of Comparative Example 1, and the obtained material was an alloy catalyst with a carbon carrier not treated by microwave-assisted phosphoric acid. The material obtained in Comparative Example 2 was simply designated as EC600-PtCo.

[0056] In order to characterize the microscopic morphology of EC600-PtCo, transmission electron microscopy (TEM) tests were carried out. Figure 9 The TEM image of EC600-PtCo and the particle size distribution diagram (inset) are shown. It can be seen from Figure 9 that the size distribution of EC600-PtCo alloy particles is relatively uneven, there are many relatively large particles, and some particles show agglomeration phenomena. The average particle size of the nanoparticles is about 4 nm. Comparing with the TEM image and the particle size distribution results of Example 2, it can be seen that the particle size distribution of P-EC600-PtCo is more concentrated, the particle size is smaller, and the particle size distribution is more uniform, indicating that the utilization rate of Pt has increased.

[0057] To further verify the durability and stability of EC600-PtCo, performance tests were conducted under a membrane electrode assembly (MEA), that is, for a proton exchange membrane fuel cell, and then performance tests were carried out.

[0058] Figure 10 Figure for the comparison of potential and power density changes of P-EC600-PtCo and EC600-PtCo before the accelerated degradation test. From Figure 10 it can be seen that both the potential and the rated power density of P-EC600-PtCo are higher than those of EC600-PtCo, indicating that the platinum-cobalt catalyst after microwave-assisted phosphoric acid treatment of the carbon support has high catalytic activity.

[0059] Figure 11 Figure for the potential and power density changes of EC600-PtCo before and after the accelerated degradation test. As Figure 11 , and Table 3 (Summary table of potential losses of fuel cells before and after accelerated degradation test) show, for EC600-PtCo at a current density of 0.8 mA / cm 2 , the potential is 721 mV. After 5000 cycles of accelerated degradation test, the potential is 691 mV, a decrease of 30 mV. Comparing with the potential loss of Example 1, it can be seen that after microwave-assisted phosphoric acid treatment of the catalyst carbon support, the stability of the catalyst has been significantly improved.

[0060] As Figure 11 , and Table 4 (Summary table of rated power density losses of fuel cells before and after accelerated degradation test) show, for EC600-PtCo at a voltage of 0.67 V, the rated power density is 805 mW / cm 2 . After 5000 cycles of accelerated degradation test, the power density is 643 mW / cm 2 , and the battery performance has decayed by 162 mW / cm 2 . Comparing with the rated power density of Example 1, it can be known that by using the carbon support treated with microwave-assisted phosphoric acid, the rated power density can be increased from 805 mW / cm 2 to 857 mW / cm 2 , with an increase of 6.5%; and, by using the carbon support treated with microwave-assisted phosphoric acid, the stability of the catalyst can be improved.

[0061] Based on the above test results, it can be known that the platinum-cobalt catalyst with ECP600JD treated by microwave-assisted phosphoric acid as the support can still maintain high catalytic activity and durability under the harsh environment of high-potential accelerated degradation test.

[0062] The parts not detailed in this application are prior art, so they are not elaborated in this application.

[0063] It will be understood that the term "a" should be construed as "at least one" or "one or more". That is, in one embodiment, the number of an element may be one, while in other embodiments, the number of the element may be multiple. The term "a" should not be construed as a limitation on the number.

[0064] Although many professional terms are used herein, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present application; any interpretation of them as any additional limitation is contrary to the spirit of the present application.

[0065] The present application is not limited to the above-described best mode. Anyone can derive other various forms of products under the inspiration of the present application. However, no matter what changes are made in its shape or structure, as long as it has a technical solution that is the same as or similar to that of the present application, it falls within the protection scope of the present application.

Claims

1. A carbon support material for oxygen reduction by microwave-assisted phosphoric acid treatment, characterized in that: The carbon carrier material comprises carbon and phosphorus, wherein the weight percentage of phosphorus is 4-6wt%; Raman spectrum of the carbon support material I D / I G The value is 1.15-1.20 to indicate an increase in the degree of graphitization; The carbon carrier material is mainly mesoporous and has a specific surface area of ​​500-600 m 2 / g, micropore volume ≤ 0.02 cm 3 / g.

2. The carbon support material according to claim 1, characterized in that The carbon carrier material is prepared by treating conductive carbon black with microwave-assisted phosphoric acid, and the conductive carbon black is one of Ketjen Black ECP300J, Ketjen Black ECP600JD, XC72R or CABOTBP2000.

3. A method for preparing a carbon carrier material for oxygen reduction by microwave-assisted phosphoric acid treatment according to claim 1 or 2, characterized in that: The following steps are involved: S1, mixing and impregnating the conductive carbon black with a phosphoric acid solution to obtain a pretreated material; S2. The pretreated material is subjected to microwave irradiation treatment under an inert atmosphere to obtain a phosphorus-doped carbon support material.

4. The preparation method according to claim 3, characterized in that: In step S1, the conductive carbon black is evenly placed in a quartz boat, and a 60-70 wt% H3PO4 solution is added dropwise to control the solid-liquid ratio to 1 g / (15-18) mL, and the mixture is immersed for 1-2 h.

5. The preparation method according to claim 4, characterized in that: In step S1, the impregnated material is transferred to a tube furnace, heated to 100-250 °C at a heating rate of 5 °C / min in an argon atmosphere, kept at this temperature for 1-3 h, and cooled naturally.

6. The preparation method according to claim 3, characterized in that: In step S2, the pretreated material is transferred to a microwave reaction vessel and treated with a microwave power of 100-600 W for 10-100 s at an argon flow rate of 300-500 SCCM; after cooling to room temperature, it is washed with pure water until neutral, filtered, vacuum dried and ground to obtain the carbon carrier material.

7. A catalyst for the microwave-assisted phosphoric acid treatment oxygen reduction of a carbon support material according to any one of claims 1 to 2, characterized in that: The catalyst comprises the carbon support material according to any one of claims 1 to 2, platinum and cobalt, wherein the mass ratio of the carbon support material, platinum acetylacetonate and cobalt acetylacetonate is 5:4:4, and the particle size of the platinum-cobalt alloy nanoparticles is 2.5-3.5 nm.

8. A method for preparing the catalyst according to claim 7, characterized in that: The following steps are involved: Precursor preparation: dissolve the carbon support material, platinum acetylacetonate and cobalt acetylacetonate in acetone, and perform rotary evaporation at 50-60°C and 80-100 r / min for 0.5-1 h to obtain a precursor powder; High temperature thermal reduction: Place the precursor powder in a tube furnace, heat to 800-900 °C at a heating rate of 5 °C / min in a hydrogen / argon mixed gas atmosphere, and keep warm for 1 h; Annealing treatment: cooling the temperature down to 600-700°C at a rate of 5°C / min, and keeping the temperature for 5-6 hours to obtain the catalyst.

9. The preparation method according to claim 8, characterized in that: The volume ratio of hydrogen to argon in the hydrogen / argon mixed gas is 1:

9.

10. Use of the catalyst according to claim 7, characterized in that: The catalyst is used in a proton exchange membrane fuel cell.

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