Carbon-supported high-loading noble metal electrocatalyst, and preparation method and application thereof

Abstract

A preparation method of a carbon-supported high-loading noble metal electrocatalyst, comprising the following steps: (1) pretreatment of the carbon carrier: treating the carbon carrier at 600-1200 DEG C for 30-120 min under an inert atmosphere, then ultrasonic dispersion in an aqueous nitric acid solution, reflux treatment at 60-120 DEG C for 1-6 h, washing with water until the filtrate pH is neutral, and drying; (2) preparation of the carbon-supported high-loading noble metal electrocatalyst: dispersing the treated carbon carrier in a mixed solution of water and a polar solvent, ultrasonic dispersion, sequentially adding a noble metal precursor solution and a reducing agent thereto, stirring for 30-40 min, adding an alkaline solution to adjust the pH to 8-10, reacting at 40-80 DEG C for 1-6 h, washing with water until the filtrate pH is neutral, and drying to obtain the carbon-supported high-loading noble metal electrocatalyst. The present application has mild reaction conditions, simple process, short preparation period, and relatively optimal catalyst performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of proton exchange membrane fuel cells, and specifically relates to a carbon-supported high-load noble metal electrocatalyst and a preparation method and application thereof. Background Art

[0002] With economic development and population growth, the total energy demand worldwide is also increasing. Currently, global energy consumption is still dominated by fossil fuels, and the large-scale consumption of fossil fuels has caused serious environmental problems. Fuel cells are a clean energy technology that can directly convert the chemical energy in fuels into electrical energy. They have the advantages of high energy conversion efficiency, cleanness and environmental protection, and can be widely used in aviation, aerospace, navigation, rail transportation, backup power supply and other fields. The catalysts used in hydrogen fuel cells are generally carbon-supported precious metal nanoparticles. Unlike the carbon-supported precious metals used in traditional industrial catalysis, precious metal electrocatalysts for fuel cells require a high precious metal loading (typically 20-60 wt%) and a small and uniform precious metal particle size distribution (2-5 nm) to ensure high precious metal utilization.

[0003] Chinese patent CN109216716A discloses a method for preparing a high-Pt-loaded Pt / C catalyst for fuel cells. The method uses chloroplatinic acid and chloroplatinates as platinum precursors, sodium carbonate and formic acid as reducing agents, and ethylene glycol as a protective agent. The reaction is carried out in a nitrogen atmosphere-protected water bath, and the resulting high-loaded Pt / C catalyst is purified. This method is simple, easy to scale up, and highly reproducible. However, the electrochemical active area of ​​the resulting electrocatalyst is only 44.1-47.3 m 2 / g Pt , indicating that the utilization rate of Pt is low and agglomeration of Pt particles may occur.

[0004] In 2020, Yuxin Li et al. (Yuxin Li, et al. Journal of Energy Chemistry, 2020, 47, 139-145) dissolved H2PtCl6 in ethylene glycol to prepare Pt colloid, adjusted the pH to 9 with NaOH, and subjected it to a microwave reaction at 160 °C to obtain a 61 wt% loaded Pt / C electrocatalyst with an average particle size of 3.9 nm and a mass specific activity of 297 mA / mg. Pt The preparation process of this study requires the use of high temperatures, resulting in energy waste. At the same time, the catalyst needs to undergo post-processing processes such as HCL sedimentation, hot water washing and air passivation after preparation. The process flow is complex and the preparation cycle is long.

[0005] The preparation method mentioned in the above study suffers from agglomeration of precious metal particles when preparing high-load carbon-supported precious metal catalysts, making it difficult to obtain a uniform particle distribution. Oswald ripening is prone to occur during electrochemical testing, resulting in reduced activity. The process flow is complex, the reaction conditions are not mild enough, the preparation cycle is long, and scale-up is difficult. At the same time, the activity and durability of the electrocatalyst are low. Summary of the Invention

[0006] To address the shortcomings of the prior art, the present invention provides a method for preparing a carbon-supported, high-precious metal electrocatalyst. This method allows for a uniformly dispersed carbon-supported, high-precious metal electrocatalyst to be obtained in a single step. Post-reaction purification requires only water washing, resulting in a simple process flow. The resulting electrocatalyst exhibits high catalytic activity in the oxygen reduction reaction. The present invention also provides a carbon-supported, high-precious metal electrocatalyst obtained using this preparation method and applications of the catalyst.

[0007] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0008] (1) Pretreatment of carbon carrier:

[0009] The carbon support is treated at 600-1200°C for 30-120 minutes under an inert atmosphere, then ultrasonically dispersed in a nitric acid aqueous solution, refluxed at 60-120°C for 1-6 hours, washed with water until the pH of the filtrate is neutral, and dried;

[0010] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0011] The treated carbon support is dispersed in a mixed solution of water and a polar solvent, ultrasonically dispersed, and a noble metal precursor solution and a reducing agent are added thereto in sequence, stirred for 30-40 minutes, and an alkaline solution is added to adjust the pH to 8-10. The mixture is reacted at 40-80°C for 1-6 hours, washed with water until the pH of the filtrate is neutral, and dried to obtain a carbon-supported high-load noble metal electrocatalyst.

[0012] Preferably, the polar solvent is at least one of methanol, ethanol, ethylene glycol, propanol, isopropanol, propylene glycol, glycerol, formamide, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, and hexamethylphosphoramide.

[0013] Preferably, the addition ratio of the carbon support, the mixed solution of water and polar solvent, and the noble metal precursor is 1 g: (100-120) mL: (4-10) mmol; the molar ratio of the noble metal precursor to the reducing agent is 1: (2-18); the concentration of the noble metal precursor solution is 20-1000 mmol / L; the ratio of the carbon support to the nitric acid aqueous solution is (0.005-0.05) g: 1 mL; and the mass concentration of the nitric acid aqueous solution is 126-504 mg / L.

[0014] Preferably, in the mixed solution of water and polar solvent, the volume ratio of water to polar solvent is 1:(0.1-1).

[0015] Preferably, the reducing agent is at least one of sodium borohydride, potassium borohydride, hydrazine hydrate, formaldehyde, ethylene glycol, hydrocyanic acid, hydrogen sulfide, and nitrous acid.

[0016] Preferably, the noble metal is at least one of platinum, rhodium, palladium, gold or silver.

[0017] Preferably, the precious metal precursor is at least one of chloroplatinic acid, chloroplatinous acid, potassium chloroplatinate, potassium chloroplatinite, sodium chloroplatinite, sodium chloroplatinite, ammonium chloroplatinate, ammonium chloroplatinite, rhodium trichloride, chlororhodic acid, potassium chlororhodate, sodium chlororhodate, ammonium chlororhodate, palladium dichloride, potassium chloropalladate, sodium chloropalladate, ammonium chloropalladate, potassium chloropalladate, sodium chloropalladate, ammonium chloropalladate, gold trichloride, chloroauric acid, sodium chloroaurate, potassium chloroaurate, ammonium chloroaurate or silver nitrate.

[0018] Preferably, the carbon support is at least one of carbon black EC600JD, carbon black EC300JD, carbon black VXC-72, carbon black BP2000, activated carbon, carbon nanotubes, carbon fibers, graphene, fullerene, or foamed carbon.

[0019] Preferably, the concentration of the alkaline solution is 0.01-8 mol / L, and the alkaline solution is an aqueous solution of potassium hydroxide, sodium hydroxide, lithium hydroxide, calcium hydroxide, ammonia water, sodium carbonate, sodium bicarbonate, sodium oxalate, sodium phosphate, or potassium carbonate.

[0020] Preferably, the inert atmosphere of the present invention is argon, helium or neon.

[0021] The carbon-supported high-load noble metal electrocatalyst prepared by the above preparation method.

[0022] The application of the carbon-supported high-load noble metal electrocatalyst in proton exchange membrane fuel cells.

[0023] Advantages of the present invention:

[0024] 1) The present invention has mild reaction conditions (40-80°C), avoiding high temperature and high pressure reaction conditions, simple process, short preparation cycle (carbon support pretreatment to catalyst posttreatment can be completed within one day), and easy scale-up;

[0025] 2) The present invention can obtain carbon-supported noble metal nanoparticle electrocatalysts with uniform dispersion and uniform particle size, and has excellent catalyst performance;

[0026] 3) The present invention can be used to prepare a variety of carbon-supported metal and alloy catalysts, including Pt, Pd, Rh, Au, and Ag, with strong universality. This preparation method provides a new design idea for the preparation of proton exchange membrane fuel cell electrocatalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a transmission electron microscopy image of the electrocatalyst in Example 1;

[0028] Figure 2 is the thermogravimetric curve of the electrocatalyst in Example 1;

[0029] Figure 3 is the polarization curve of the electrocatalyst in the oxygen reduction reaction in Example 1;

[0030] Figure 4 is a transmission electron microscopy image of the electrocatalyst in Example 2;

[0031] Figure 5 TEM image of the electrocatalyst prepared using an untreated carbon support in Comparative Example 1;

[0032] Figure 6 TEM images of different volume ratios of water to polar solvent in Comparative Example 2;

[0033] Figure 7 Transmission electron microscopy images of electrocatalysts prepared with different noble metal precursor concentrations in Comparative Example 3;

[0034] Figure 8 Thermogravimetric curves of the electrocatalysts prepared with different amounts of reducing agent added in Comparative Example 4;

[0035] Figure 9 Transmission electron microscopy images of the electrocatalysts prepared at different reaction pH values ​​in Comparative Example 5;

[0036] Figure 10 Polarization curves of the electrocatalysts prepared at different reaction temperatures in comparative example 6 in the oxygen reduction reaction;

[0037] Figure 11 This is a transmission electron micrograph of the electrocatalyst obtained by adjusting the pH and adding a reducing agent in Comparative Example 7. DETAILED DESCRIPTION

[0038] Example 1

[0039] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0040] (1) Pretreatment of carbon carrier:

[0041] 5 g of carbon black EC-600 was used as a carbon support and treated at 850 °C for 60 min under argon atmosphere. Then, it was ultrasonically dispersed in 500 mL of 378 mg / L nitric acid aqueous solution and refluxed at 90 °C for 3 h. The filtrate was washed with water until the pH of the filtrate was neutral and dried at 80 °C.

[0042] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0043] Take 500 mL of a mixed solution of water and glycerol, wherein the volume ratio of water to glycerol is 1:0.1, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 40 mL of a 500 mmol / L H2PtCl6 aqueous solution and 7.04 g (235 mmol) of formaldehyde thereto in sequence, stir for 30 min, add a 2 mol / L KOH aqueous solution to adjust the pH to 8, react at 40 ° C for 4 h, wash with water until the pH of the filtrate is neutral, and dry at 80 ° C to obtain a carbon-supported high-load precious metal electrocatalyst Pt / C.

[0044] The electrocatalyst obtained in Example 1 was subjected to transmission electron microscopy, and the results are shown in FIG. Figure 1 ,Depend on Figure 1 It was found that the Pt particles in the prepared carbon-supported Pt / C electrocatalyst were uniformly supported on the surface of the carbon support;

[0045] The electrocatalyst obtained in Example 1 was subjected to thermogravimetric analysis in the temperature range of 100-700°C in air. Figure 2 ,Depend on Figure 2 The Pt loading in the carbon-supported Pt / C electrocatalyst was 58.5 wt%;

[0046] The electrochemical performance was determined by the standard three-electrode method. The carbon-supported noble metal electrocatalyst prepared in Example 1 was made into a thin film working electrode. The test conditions were: in an oxygen-saturated 0.1 mol / L HClO4 aqueous solution at 25°C, a potential sweep test was performed at a voltage of 0-1.2 V (vs RHE). The polarization curve in the redox state was shown in FIG. Figure 3 , the oxygen reduction activity is higher than that of commercial Pt / C (Pt / C JM), due to Figure 3 The calculated mass specific activity of the electrocatalyst at 0.9 V is 252 mA / mg Pt -1 , which can reach 1.4 times that of commercial Pt / C catalyst.

[0047] Example 2

[0048] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0049] (1) Pretreatment of carbon carrier:

[0050] 5 g of carbon black EC-600 was used as a carbon support and treated at 850 °C for 60 min under argon atmosphere. Then, it was ultrasonically dispersed in 500 mL of 378 mg / L nitric acid aqueous solution and refluxed at 90 °C for 3 h. The filtrate was washed with water until the pH of the filtrate was neutral and dried at 80 °C.

[0051] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0052] Take 500 mL of a mixed solution of water and glycerol, wherein the volume ratio of water to glycerol is 1:0.1, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 53 mL of a 500 mmol / L H2PtCl6 aqueous solution and 7.04 g (235 mmol) of formaldehyde thereto in sequence, stir for 30 min, add 2 mol / L KOH aqueous solution to adjust the pH to 8, react at 40 ° C for 4 h, wash with water until the pH of the filtrate is neutral, and dry at 80 ° C to obtain a carbon-supported high-load precious metal electrocatalyst Pt / C.

[0053] The electrocatalyst obtained in Example 2 was subjected to transmission electron microscopy, and the results are shown in FIG. Figure 4 ,Depend on Figure 4 It was found that the Pt particles in the prepared carbon-supported Pt / C electrocatalyst with a higher loading were uniformly supported on the surface of the carbon support, with an average particle size of 4.7 nm.

[0054] Example 3

[0055] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0056] (1) Pretreatment of carbon carrier:

[0057] 5 g of carbon black EC-600 was used as a carbon support and treated at 900 °C for 60 min under argon atmosphere. It was then ultrasonically dispersed in 500 mL of a 378 mg / L aqueous nitric acid solution and refluxed at 90 °C for 3 h. The filtrate was washed with water until the pH value was neutral and dried at 80 °C.

[0058] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0059] Take 500 mL of a mixed solution of water and ethanol, wherein the volume ratio of water to ethanol is 1:0.2, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 94 mL of a 500 mmol / L H2PdCl6 aqueous solution and 7.04 g (235 mmol) of formaldehyde thereto in sequence, stir for 30 min, add a 2 mol / L KOH aqueous solution to adjust the pH to 8, react at 40 ° C for 4 h, wash with water until the pH of the filtrate is neutral, and dry at 80 ° C to obtain a carbon-supported high-load precious metal electrocatalyst Pd / C.

[0060] Example 4

[0061] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0062] (1) Pretreatment of carbon carrier:

[0063] 5 g of carbon black EC-600 was used as a carbon support and treated at 850 °C for 60 min under argon atmosphere. It was then ultrasonically dispersed in 800 mL of a 378 mg / L aqueous nitric acid solution and refluxed at 90 °C for 3 h. The filtrate was washed with water until the pH value was neutral and dried at 80 °C.

[0064] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0065] Take 500 mL of a mixed solution of water and N,N-dimethylformamide, wherein the volume ratio of water to N,N-dimethylformamide is 1:0.1, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 40 mL of a 500 mmol / L H2PtCl6 aqueous solution and 10.56 g (352 mmol) of formaldehyde thereto in sequence, stir for 30 min, add a 2 mol / L KOH aqueous solution to adjust the pH to 8, react at 40 ° C for 4 h, wash with water until the pH of the filtrate is neutral, and dry at 80 ° C to obtain a carbon-supported high-load precious metal electrocatalyst Pt / C.

[0066] Example 5

[0067] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0068] (1) Pretreatment of carbon carrier:

[0069] 5 g of carbon black EC-600 was used as a carbon support and treated at 850 °C for 60 min under a helium atmosphere. It was then ultrasonically dispersed in 500 mL of a 378 mg / L aqueous nitric acid solution and refluxed at 90 °C for 3 h. The filtrate was washed with water until the pH of the filtrate was neutral and dried at 80 °C.

[0070] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0071] Take 500 mL of a mixed solution of water and isopropanol, wherein the volume ratio of water to isopropanol is 1:0.3, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 40 mL of a 500 mmol / L H2PtCl6 aqueous solution and 7.68 g (226 mmol) of hydrogen sulfide thereto in sequence, stir for 30 min, add 2 mol / L ammonia water to adjust the pH to 8, react at 40 ° C for 4 h, wash with water until the pH of the filtrate is neutral, and dry at 80 ° C to obtain a carbon-supported high-load precious metal electrocatalyst Pt / C.

[0072] Example 6

[0073] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0074] (1) Pretreatment of carbon carrier:

[0075] 5 g of carbon black EC-600 was used as a carbon support and treated at 850 °C for 60 min under argon atmosphere. It was then ultrasonically dispersed in 500 mL of a 378 mg / L aqueous nitric acid solution and refluxed at 80 °C for 3 h. The filtrate was washed with water until the pH value was neutral and dried at 80 °C.

[0076] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0077] Take 500 mL of a mixed solution of water and glycerol, wherein the volume ratio of water to glycerol is 1:0.1, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 40 mL of a 500 mmol / L H2PtCl6 aqueous solution and 6.04 g (97 mmol) of ethylene glycol thereto in sequence, stir for 30 min, add a 4 mol / L KOH aqueous solution to adjust the pH to 9, react at 70 ° C for 4 h, wash with water until the pH of the filtrate is neutral, and dry at 80 ° C to obtain a carbon-supported high-load precious metal electrocatalyst Pt / C.

[0078] Example 7

[0079] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0080] (1) Pretreatment of carbon carrier:

[0081] 5 g of carbon black EC-600 was used as a carbon support and treated at 850 °C for 60 min under argon atmosphere. It was then ultrasonically dispersed in 500 mL of a 504 mg / L aqueous nitric acid solution and refluxed at 90 °C for 3 h. The filtrate was washed with water until the pH of the filtrate was neutral and dried at 80 °C.

[0082] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0083] Take 500 mL of a mixed solution of water and glycerol, wherein the volume ratio of water to glycerol is 1:0.1, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 40 mL of a 500 mmol / L H2PtCl6 aqueous solution and 7.04 g (235 mmol) of formaldehyde thereto in sequence, stir for 30 min, add a 2 mol / L KOH aqueous solution to adjust the pH to 8, react at 40 ° C for 4 h, wash with water until the pH of the filtrate is neutral, and dry at 80 ° C to obtain a carbon-supported high-load precious metal electrocatalyst Pt / C.

[0084] Example 8

[0085] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0086] (1) Pretreatment of carbon carrier:

[0087] 5 g of carbon black EC-600 was used as a carbon support and treated at 850 °C for 60 min under argon atmosphere. Then, it was ultrasonically dispersed in 500 mL of 378 mg / L nitric acid aqueous solution and refluxed at 90 °C for 3 h. The filtrate was washed with water until the pH of the filtrate was neutral and dried at 80 °C.

[0088] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0089] Take 500 mL of a mixed solution of water and glycerol, wherein the volume ratio of water to glycerol is 1:0.1, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 40 mL of a 500 mmol / L H2PtCl6 aqueous solution and 7.04 g (235 mmol) of formaldehyde thereto in sequence, stir for 30 min, add a 2 mol / L KOH aqueous solution to adjust the pH to 8, react at 40 ° C for 6 h, wash with water until the pH of the filtrate is neutral, and dry at 80 ° C to obtain a carbon-supported high-load precious metal electrocatalyst Pt / C.

[0090] Example 9

[0091] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0092] (1) Pretreatment of carbon carrier:

[0093] 5 g of carbon black EC-600 was used as a carbon support and treated at 600 °C for 120 min under an argon atmosphere. It was then ultrasonically dispersed in 1000 mL of a 126 mg / L nitric acid aqueous solution and refluxed at 60 °C for 6 h. The filtrate was washed with water until the pH value was neutral and dried at 80 °C.

[0094] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0095] Take 600 mL of a mixed solution of water and dimethyl sulfoxide, wherein the volume ratio of water to dimethyl sulfoxide is 1:1, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 20 mL of a 1000 mmol / L rhodium trichloride aqueous solution and 8.64 g (160 mmol) of potassium borohydride thereto in sequence, stir for 40 minutes, add 8 mol / L KOH aqueous solution to adjust the pH to 10, react at 80°C for 1 hour, wash with water until the pH of the filtrate is neutral, and dry at 80°C to obtain a carbon-supported high-load precious metal electrocatalyst Rh / C.

[0096] Example 10

[0097] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0098] (1) Pretreatment of carbon carrier:

[0099] 5 g of carbon black EC-600 was used as a carbon support and treated at 1200 °C for 30 min under argon atmosphere. Then, it was ultrasonically dispersed in 100 mL of 504 mg / L nitric acid aqueous solution and refluxed at 120 °C for 1 h. The filtrate was washed with water until the pH of the filtrate was neutral and dried at 80 °C.

[0100] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0101] Take 500 mL of a mixed solution of water and acetonitrile, wherein the volume ratio of water to acetonitrile is 1:0.5, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 1000 mL of 20 mmol / L H2AuCl4 aqueous solution and 2.7 g (100 mmol) of hydrocyanic acid thereto in sequence, stir for 40 min, add 0.01 mol / L KOH aqueous solution to adjust the pH to 8, react at 40 ° C for 6 h, wash with water until the pH of the filtrate is neutral, and dry at 80 ° C to obtain a carbon-supported high-load precious metal electrocatalyst Au / C.

[0102] Example 11

[0103] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0104] (1) Pretreatment of carbon carrier:

[0105] 5 g of carbon black EC-600 was used as a carbon support and treated at 600 °C for 120 min under an argon atmosphere. It was then ultrasonically dispersed in 500 mL of a 378 mg / L aqueous nitric acid solution and refluxed at 90 °C for 3 h. The filtrate was washed with water until the pH of the filtrate was neutral and dried at 80 °C.

[0106] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0107] Take 500 mL of a mixed solution of water and hexamethylphosphoramide, wherein the volume ratio of water to hexamethylphosphoramide is 1:0.2, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 40 mL of a 500 mmol / LAgNO3 aqueous solution and 1.88 g (40 mmol) of nitrous acid thereto in sequence, stir for 30 min, add a 2 mol / L KOH aqueous solution to adjust the pH to 8, react at 40 ° C for 4 h, wash with water until the pH of the filtrate is neutral, and dry at 80 ° C to obtain a carbon-supported high-load precious metal electrocatalyst Ag / C.

[0108] The comparison of electrochemical active area and mass specific activity of the electrocatalysts prepared in different embodiments is shown in Table 1.

[0109] Table 1 Electrochemical active area and mass specific activity

[0110] <![CDATA[电化学活性面积(m 2 / g Pt )]]> <![CDATA[质量比活性(mA / mg Pt )]]> Example 1 75.1 252 Example 2 71.5 221 Example 4 74.2 244 Example 5 80.1 270 Example 6 74.3 237 Example 7 77.9 219 Example 8 69.8 210

[0111] Comparative Example 1

[0112] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0113] (1) Pretreatment of carbon carrier:

[0114] 5 g of carbon black EC-600 was used as a carbon support and treated at 850 °C for 60 min under argon atmosphere;

[0115] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0116] Take 500 mL of a mixed solution of water and glycerol, wherein the volume ratio of water to glycerol is 1:0.1, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 40 mL of a 500 mmol / L H2PtCl6 aqueous solution and 7.04 g (235 mmol) of formaldehyde thereto in sequence, stir for 30 min, add a 2 mol / L KOH aqueous solution to adjust the pH to 8, react at 40 ° C for 4 h, wash with water until the pH of the filtrate is neutral, and dry at 80 ° C to obtain a carbon-supported high-load precious metal electrocatalyst Pt / C.

[0117] The transmission electron microscopy of the electrocatalyst obtained in Comparative Example 1 is shown in Table 1. Figure 5 As shown in Table 1, the carbon carrier is not treated by the oxidizing acid, and the surface hydrophilicity is not good, and the effect of supporting the noble metal particles is not good, and the particle agglomeration occurs. Figure 5 As shown in Table 1, the carbon carrier is not treated by the oxidizing acid, and the surface hydrophilicity is not good, and the effect of supporting the noble metal particles is not good, and the particle agglomeration occurs.

[0118] Comparative Example 2

[0119] A preparation method of a carbon-supported high-loading noble metal electrocatalyst, comprising the following steps:

[0120] (1) Pretreatment of the carbon carrier:

[0121] 5g of carbon black EC-600 is taken as the carbon carrier, treated at 850℃ for 60min under argon atmosphere, then ultrasonically dispersed in 500mL of 378mg / L nitric acid aqueous solution, treated by reflux at 90℃ for 3h, washed with water until the pH of the filtrate is neutral, and dried at 80℃;

[0122] (2) Preparation of the carbon-supported high-loading noble metal electrocatalyst:

[0123] A mixed solution of water and glycerol 500mL is taken, wherein the volume ratio of water to glycerol is 1:2, the carbon carrier obtained in step (1) is dispersed therein, ultrasonically dispersed, 40mL of 500mmol / L H2PtCl6 aqueous solution and 7.04g (235mmol) of formaldehyde are sequentially added thereto, stirred for 30min, 2mol / L KOH aqueous solution is added to adjust the pH to 8, reacted at 40℃ for 4h, washed with water until the pH of the filtrate is neutral, and dried at 80℃ to obtain the carbon-supported high-loading noble metal electrocatalyst Pt / C.

[0124] The transmission electron microscopy of the electrocatalyst obtained in Comparative Example 2 is shown in Table 1. Figure 6 As shown in Table 1, the carbon carrier is not treated by the oxidizing acid, and the surface hydrophilicity is not good, and the effect of supporting the noble metal particles is not good, and the particle agglomeration occurs. Figure 6 As shown in Table 1, the carbon carrier is not treated by the oxidizing acid, and the surface hydrophilicity is not good, and the effect of supporting the noble metal particles is not good, and the particle agglomeration occurs.

[0125] Comparative Example 3

[0126] A preparation method of a carbon-supported high-loading noble metal electrocatalyst, comprising the following steps:

[0127] (1) Pretreatment of the carbon carrier:

[0128] 5g of carbon black EC-600 is taken as the carbon carrier, treated at 850℃ for 60min under argon atmosphere, then ultrasonically dispersed in 500mL of 378mg / L nitric acid aqueous solution, treated by reflux at 90℃ for 3h, washed with water until the pH of the filtrate is neutral, and dried at 80℃;

[0129] (2) Preparation of the carbon-supported high-loading noble metal electrocatalyst:

[0130] Take 500 mL of a mixed solution of water and glycerol, wherein the volume ratio of water to glycerol is 1:0.1, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 10 mL of 2000 mmol / L H2PtCl6 aqueous solution and 7.04 g (235 mmol) of formaldehyde thereto in sequence, stir for 30 min, add 2 mol / L KOH aqueous solution to adjust the pH to 8, react at 40 ° C for 4 h, wash with water until the pH of the filtrate is neutral, and dry at 80 ° C to obtain a carbon-supported high-load precious metal electrocatalyst Pt / C.

[0131] The electrocatalyst obtained in Comparative Example 3 was subjected to transmission electron microscopy, and the results are shown in FIG. Figure 7 ,Depend on Figure 7 It was found that when the total molar amount of Pt remained unchanged, increasing the concentration of the noble metal precursor would reduce the uniformity of the obtained metal particles and result in the appearance of large particles.

[0132] Comparative Example 4

[0133] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0134] (1) Pretreatment of carbon carrier:

[0135] 5 g of carbon black EC-600 was used as a carbon support and treated at 850 °C for 60 min under argon atmosphere. Then, it was ultrasonically dispersed in 500 mL of 378 mg / L nitric acid aqueous solution and refluxed at 90 °C for 3 h. The filtrate was washed with water until the pH of the filtrate was neutral and dried at 80 °C.

[0136] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0137] Take 500 mL of a mixed solution of water and glycerol, wherein the volume ratio of water to glycerol is 1:0.1, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 40 mL of a 500 mmol / L H2PtCl6 aqueous solution and 0.6 g (20 mmol) of formaldehyde thereto in sequence, stir for 30 min, add a 2 mol / L KOH aqueous solution to adjust the pH to 8, react at 40 ° C for 4 h, wash with water until the pH of the filtrate is neutral, and dry at 80 ° C to obtain a carbon-supported high-load precious metal electrocatalyst Pt / C.

[0138] The electrocatalyst obtained in Comparative Example 4 was subjected to thermogravimetric analysis, and the results are shown in FIG. Figure 8 ,Depend on Figure 8 It was found that reducing the amount of reducing agent significantly reduced the loading of precious metals to only 32 wt%, indicating that part of the precious metal precursors were not effectively reduced.

[0139] Comparative Example 5

[0140] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0141] (1) Pretreatment of carbon carrier:

[0142] 5 g of carbon black EC-600 was used as a carbon support and treated at 850 °C for 60 min under argon atmosphere. Then, it was ultrasonically dispersed in 500 mL of 378 mg / L nitric acid aqueous solution and refluxed at 90 °C for 3 h. The filtrate was washed with water until the pH of the filtrate was neutral and dried at 80 °C.

[0143] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0144] Take 500 mL of a mixed solution of water and glycerol, wherein the volume ratio of water to glycerol is 1:0.1, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 40 mL of a 500 mmol / L H2PtCl6 aqueous solution and 7.04 g (235 mmol) of formaldehyde thereto in sequence, stir for 30 min, add a 2 mol / L KOH aqueous solution to make the pH of the system reach 6, react at 40°C for 4 h, wash with water until the pH of the filtrate is neutral, and dry at 80°C to obtain a carbon-supported high-load precious metal electrocatalyst Pt / C.

[0145] The electrocatalyst obtained in Comparative Example 5 was subjected to transmission electron microscopy, and the results are shown in FIG. Figure 9 ,Depend on Figure 9 It was found that when the pH was not adjusted to alkaline, the surface particles of the prepared electrocatalyst were in an amorphous form and agglomerated.

[0146] Comparative Example 6

[0147] A method for preparing a carbon-supported high-load noble metal electrocatalyst comprises the following steps:

[0148] (1) Pretreatment of carbon carrier:

[0149] 5 g of carbon black EC-600 was used as a carbon support and treated at 850 °C for 60 min under argon atmosphere. Then, it was ultrasonically dispersed in 500 mL of 378 mg / L nitric acid aqueous solution and refluxed at 90 °C for 3 h. The filtrate was washed with water until the pH of the filtrate was neutral and dried at 80 °C.

[0150] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0151] Take 500 mL of a mixed solution of water and glycerol, wherein the volume ratio of water to glycerol is 1:0.1, disperse the carbon support obtained in step (1) therein, and ultrasonically disperse it. Then, add 40 mL of a 500 mmol / L H2PtCl6 aqueous solution and 7.04 g (235 mmol) of formaldehyde thereto in sequence, stir for 30 min, add a 2 mol / L KOH aqueous solution to adjust the pH to 8, react at 20°C for 4 h, wash with water until the pH of the filtrate is neutral, and dry at 80°C to obtain a carbon-supported high-load precious metal electrocatalyst Pt / C.

[0152] The electrochemical performance was determined by the standard three-electrode method. The Pt / C electrocatalyst prepared in Comparative Example 6 was made into a thin film working electrode. The test conditions were: in an oxygen-saturated 0.1 mol / L HClO4 aqueous solution at 25 °C, a potential sweep test was performed at a voltage of 0-1.2 V (vs RHE). The polarization curve in the redox state was shown in FIG. Figure 10 ,Depend on Figure 10 It was found that lowering the reaction temperature was not conducive to the formation of uniform Pt particle dispersion, and the oxygen reduction electrocatalytic activity was poor, with a mass specific activity of only 131 mA / mg. Pt .

[0153] Comparative Example 7

[0154] (1) Pretreatment of carbon carrier:

[0155] 5 g of carbon black EC-600 was used as a carbon support and treated at 850 °C for 60 min under argon atmosphere. Then, it was ultrasonically dispersed in 500 mL of 378 mg / L nitric acid aqueous solution and refluxed at 90 °C for 3 h. The filtrate was washed with water until the pH of the filtrate was neutral and dried at 80 °C.

[0156] (2) Preparation of carbon-supported high-load noble metal electrocatalysts:

[0157] Take 500 mL of a mixed solution of water and glycerol, wherein the volume ratio of water to glycerol is 1:0.1, disperse the carbon support obtained in step (1) therein, ultrasonically disperse, and sequentially add 40 mL of a 500 mmol / L H2PtCl6 aqueous solution, add a 2 mol / L KOH aqueous solution to adjust the pH to 8, then add 7.04 g (235 mmol) of formaldehyde, stir for 30 minutes, react at 40°C for 4 hours, wash with water until the pH of the filtrate is neutral, and dry at 80°C to obtain a carbon-supported high-load precious metal electrocatalyst Pt / C.

[0158] The transmission electron microscopy of the electrocatalyst obtained in Comparative Example 7 shows that in the Pt / C catalyst obtained by adding a reducing agent after adjusting the pH value, the particle size of the Pt particles is significantly increased and agglomerates are generated.

Claims

1. A method for preparing a carbon-supported high-load noble metal electrocatalyst, characterized in that: The following steps are involved: (1) Pretreatment of carbon carrier: The carbon support is treated at 600-1200°C for 30-120 minutes under an inert atmosphere, then ultrasonically dispersed in a nitric acid aqueous solution, refluxed at 60-120°C for 1-6 hours, washed with water until the pH of the filtrate is neutral, and dried; (2) Preparation of carbon-supported high-load noble metal electrocatalysts: The treated carbon support is dispersed in a mixed solution of water and a polar solvent, and ultrasonically dispersed. A noble metal precursor solution and a reducing agent are added thereto in sequence, and stirred for 30-40 minutes. An alkaline solution is added to adjust the pH to 8-10, and the mixture is reacted at 40-80°C for 1-6 hours. The mixture is washed with water until the pH of the filtrate is neutral, and dried to obtain a carbon-supported high-load noble metal electrocatalyst. The carbon support, the mixed solution of water and polar solvent, and the noble metal precursor are added in a ratio of 1 g: (100-120) mL: (4-10) mmol; the molar ratio of the noble metal precursor to the reducing agent is 1: (2-18); the concentration of the noble metal precursor solution is 20-1000 mmol / L; the ratio of the carbon support to the nitric acid aqueous solution is (0.005-0.05) g: 1 mL; and the mass concentration of the nitric acid aqueous solution is 126-504 mg / L. In the mixed solution of water and polar solvent, the volume ratio of water to polar solvent is 1:(0.1-1).

2. The method for preparing a carbon-supported high-load noble metal electrocatalyst according to claim 1, characterized in that: The polar solvent is at least one of methanol, ethanol, ethylene glycol, propanol, isopropanol, propylene glycol, glycerol, formamide, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, and hexamethylphosphoramide.

3. The method for preparing a carbon-supported high-load noble metal electrocatalyst according to claim 2, characterized in that: The reducing agent is at least one of sodium borohydride, potassium borohydride, hydrazine hydrate, formaldehyde, ethylene glycol, hydrocyanic acid, hydrogen sulfide, and nitrous acid.

4. The method for preparing a carbon-supported high-load noble metal electrocatalyst according to claim 3, characterized in that: The precious metal precursor is at least one of chloroplatinic acid, chloroplatinous acid, potassium chloroplatinate, potassium chloroplatinite, sodium chloroplatinate, sodium chloroplatinite, ammonium chloroplatinate, ammonium chloroplatinite, rhodium trichloride, chlororhodic acid, potassium chlororhodate, sodium chlororhodate, ammonium chlororhodate, palladium dichloride, potassium chloropalladate, sodium chloropalladate, ammonium chloropalladate, potassium chloropalladate, sodium chloropalladate, ammonium chloropalladate, gold trichloride, chloroauric acid, sodium chloroaurate, potassium chloroaurate, ammonium chloroaurate or silver nitrate.

5. The method for preparing a carbon-supported high-load noble metal electrocatalyst according to claim 4, characterized in that: The carbon carrier is at least one of carbon black EC600JD, carbon black EC300JD, carbon black VXC-72, carbon black BP2000, activated carbon, carbon nanotubes, carbon fibers, graphene, fullerene or foamed carbon.

6. The method for preparing a carbon-supported high-load noble metal electrocatalyst according to claim 5, characterized in that: The concentration of the alkaline solution is 0.01-8 mol / L, and the alkaline solution is an aqueous solution of potassium hydroxide, sodium hydroxide, lithium hydroxide, calcium hydroxide, ammonia water, sodium carbonate, sodium bicarbonate, sodium oxalate, sodium phosphate, or potassium carbonate.

7. A carbon-supported high-load noble metal electrocatalyst prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the carbon-supported high-load noble metal electrocatalyst according to claim 7 in a proton exchange membrane fuel cell.

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