Preparation method of high-performance superlow-palladium-capacity anode electrocatalyst Pd-CoP/C of direct formic acid fuel cell

A technology of fuel cells and electrocatalysts, which is applied to battery electrodes, circuits, electrical components, etc., can solve problems limited to the research stage, reduce the utilization rate of precious metals, and limited catalytic activity, and achieve simple processing methods, excellent electrochemical performance, Simple operation effect

Inactive Publication Date: 2015-03-11

CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI

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AI-Extracted Technical Summary

Problems solved by technology

However, the above preparation methods have their own shortcomings. For example, the preparation of Pd-M (M=Pt, Ir, Sn, Au, Co, etc.) can improve the activity of the catalyst to a certain extent, but the dissolution and aggregation of M in the battery environment is fatal. At the same time, Pd, Pt, Au, etc., as noble metals, cannot be widely developed and applied, and the current technical level is limited to the research stage; although non-metallic phosphorus doping can improve the stability...

Abstract

The invention relates to a preparation method of a high-performance superlow-palladium-capacity anode electrocatalyst Pd-CoP/C of a direct formic acid fuel cell and belongs to the technical field of fuel cells. The preparation method comprises the following steps: dispersing a carrier and cobalt chloride hexahydrate in water, drying to obtain a first compound carrier by distillation after ultrasonic dispersing and stirring; mixing and grinding the first compound carrier and hydrated sodium hypophosphite for one-hour reaction, and washing and drying the reactant to obtain a second compound carrier; dispersing the second compound carrier in glycol, adding hexachloropalladate, and performing ultrasonic dispersing and stirring to obtain a first turbid liquid; stirring the first turbid liquid at the room temperature, and regulating the pH value with sodium hydroxide to obtain a second turbid liquid; performing microwave radiation on the second turbid liquid, and obtaining a supported palladium catalyst. The palladium-based catalyst prepared by the method has extremely high catalytic activity and relatively high stability to formic acid electro-oxidation. Meanwhile, the capacity of the precious metal palladium can be reduced, and the method is simple to operate, short in preparation period and suitable for mass production.

Application Domain

Cell electrodes

Technology Topic

Formic acidDistillation +13

Image

Examples

Experimental program(7)
Comparison scheme(1)

Example Embodiment

[0047] Example 1

[0048] (1) Add 0.60g of cobalt chloride hexahydrate and 1.6889g of Vulcan XC-72 produced by American Cabot Company to a beaker containing 50mL of secondary water, sonicate for 30min and stir for 60min, then put it in a muffle furnace at 100°C to dry A black mixture is obtained from the moisture, and then 2.016g of the black mixture and 1.32g of hydrated sodium hypophosphite are added to a quartz boat and placed in a tube furnace, and calcined in a nitrogen atmosphere at 800°C for 60 minutes, where the oxygen flow rate is 80cc min -1 ,Tube furnace from room temperature to 5℃min -1 The heating rate was raised to 800°C, and the composite carrier prepared was marked as CoP/C-10% (where 10% represents the mass percentage of CoP in the composite carrier).

[0049] (2) Weigh 190 mg of CoP/C-10% prepared in step (1), add it to a beaker containing 100 mL of ethylene glycol, and add chloropalladic acid containing 10 mg of palladium at the same time, sonicate for 30 minutes and stir for 5 hours, then use hydrogen Adjust the pH value of sodium oxide to 11.0, immediately put the above solution into a 700W microwave oven and irradiate it for 3 minutes to reduce chloropalladic acid into palladium nanoparticles. The prepared catalyst is labeled Pd-CoP/C-10%, where palladium is The mass percentage in the catalyst is 5%.

[0050] (3) Add 50μL of Aldrich's 5% Nafion solution to the beaker containing 950μL of ethanol solution, then add 5mg of the Pd-CoP/C-10% catalyst prepared in step (2) to it, and ultrasonically disperse 30min, get the mixed solution; take 5μL of the above solution and drop it on the glassy carbon electrode, and dry it at room temperature to get the thin film electrode; Hg/Hg 2 Cl 2 A three-electrode system with the electrode as the reference electrode and the Pt sheet as the counter electrode. Cyclic voltammetry was tested in 0.5 mol/L sulfuric acid and 0.5 mol/L formic acid solution deoxygenated by nitrogen. The scanning speed was 50 mV/s. See results figure 1 , figure 1 Is the cyclic voltammetry curve of the catalyst in formic acid solution, where the curve Pd/C-JM is the cyclic voltammetry curve of the commercial catalyst in formic acid solution provided in Comparative Example 1, which is represented by figure 1 It can be seen that the mass specific activity of the Pd-CoP/C-10% catalyst prepared in Example 1 is 1782.3 mA mg -1 Pd, much higher than the mass specific activity (783.1mA mg) of the commercial Pd/C catalyst (Pd/C-JM) provided in Comparative Example 1. -1 Pd).

[0051] (4) Weigh a certain amount of CoP/C-10% carrier and Pd-CoP/C-10% catalyst prepared in step (1) and step (2) to measure XRD respectively. XRD spectrum such as figure 2 with image 3 Shown. by figure 2 with image 3 It can be seen that the prepared carrier and catalyst are consistent with the standard card.

[0052] (5) Weigh a certain amount of Pd-CoP/C-10% catalyst prepared in step (2) to measure TEM (see Figure 5 ).

[0053] (6) Weigh a certain amount of the Pd-CoP/C-10% catalyst prepared in step (2) to measure XPS (see Figure 4 ).

Example Embodiment

[0064] Example 2

[0065] (1) Add 1.20g of cobalt chloride hexahydrate and 1.5016g of Vulcan XC-72 produced by American Cabot Company to a beaker containing 50mL of secondary water, sonicate for 30min, stir for 60min, and then put it in a muffle furnace at 110°C to dry A black mixture is obtained by moisture, and then 2.157g of the black mixture and 2.64g of hydrated sodium hypophosphite are added to a quartz boat and placed in a tube furnace, and calcined in a nitrogen atmosphere at 800°C for 90 minutes, where the oxygen flow rate is 80cc min -1 ,Tube furnace from room temperature to 5℃min -1 The heating rate was raised to 800°C, and the composite carrier prepared was marked as CoP/C-20% (where 20% represents the mass percentage of CoP in the composite carrier).

[0066] (2) Weigh 190 mg of CoP/C-20% prepared in step (1), add it to a beaker containing 100 mL of ethylene glycol, and add chloropalladic acid containing 10 mg of palladium at the same time, sonicate for 30 minutes and stir for 5 hours, then use hydrogen Adjust the pH value of sodium oxide to 11.0, immediately put the above solution in a 700W microwave oven and irradiate it for 3 minutes to reduce chloropalladic acid to palladium nanoparticles. The prepared catalyst is labeled Pd-CoP/C-20%, where palladium is The mass percentage in the catalyst is 5%.

[0067] (3) Add 50 μL of Aldrich's 5% Nafion solution produced by Aldrich to a beaker containing 950 μL of ethanol solution, and then add 5 mg of Pd-CoP/C-20% catalyst prepared in step (2) to it, and ultrasonically disperse 30min, get the mixed solution; take 5μL of the above mixed solution and drop it on the glassy carbon electrode, and dry it at room temperature to get the thin film electrode; use Hg/Hg 2 Cl 2 A three-electrode system with the electrode as the reference electrode and the Pt sheet as the counter electrode. Cyclic voltammetry was tested in 0.5 mol/L sulfuric acid and 0.5 mol/L formic acid solution deoxygenated by nitrogen. The scanning speed was 50 mV/s. See results figure 1 , figure 1 Is the cyclic voltammetry curve of the catalyst in formic acid solution, where the curve Pd/C-JM is the cyclic voltammetry curve of the commercial catalyst in formic acid solution provided in Comparative Example 1, which is represented by figure 1 It can be seen that the mass specific activity of the Pd-CoP/C-20% catalyst prepared in Example 2 is 2076.1 mA mg -1 Pd, much higher than the mass specific activity (783.1mA mg) of the commercial Pd/C catalyst (Pd/C-JM) provided in Comparative Example 1. -1 Pd).

[0068] (4) Weigh a certain amount of CoP/C-20% carrier and Pd-CoP/C-20% catalyst prepared in step (1) and step (2) to measure XRD (see figure 2 and image 3 ).

[0069] (5) Weigh a certain amount of Pd-CoP/C-20% catalyst prepared in step (2) to measure TEM (see Image 6 ).

[0070] (6) Weigh a certain amount of the Pd-CoP/C-20% catalyst prepared in step (2) to measure XPS (see Figure 4 ).

Example Embodiment

[0071] Example 3

[0072] (1) Add 1.20g of cobalt chloride hexahydrate and 0.876g of Vulcan XC-72 produced by American Cabot Company to a beaker containing 50mL of secondary water, sonicate for 30min and stir for 60min, then put it in a muffle furnace at 120°C to dry The black mixture is obtained by moisture, and then 1.5313g of the black mixture and 2.64g of hydrated sodium hypophosphite are added to a quartz boat and placed in a tube furnace, and calcined in a nitrogen atmosphere at 800°C for 120 minutes, where the oxygen flow rate is 80cc min -1 ,Tube furnace from room temperature to 5℃min -1 The heating rate was raised to 800°C, and the composite carrier prepared was marked as CoP/C-30% (where 30% represents the mass percentage of CoP in the composite carrier).

[0073] (2) Weigh 190 mg of CoP/C-30% prepared in step (1), add it to a beaker containing 100 mL of ethylene glycol, and add chloropalladic acid containing 10 mg of palladium at the same time, sonicate for 30 minutes and stir for 5 hours, then use hydrogen Adjust the pH value of sodium oxide to 11.0, immediately put the above solution in a 700W microwave oven and irradiate it for 3 minutes to reduce chloropalladic acid to palladium nanoparticles. The prepared catalyst is labeled Pd-CoP/C-30%, where palladium is The mass percentage in the catalyst is 5%.

[0074] (3) Add 50μL of Aldrich's 5% Nafion solution produced by Aldrich to a beaker containing 950μL of ethanol solution, and then add 5mg of the Pd-CoP/C-30% catalyst prepared in step (2) to it, and ultrasonically disperse 30min, get the mixed solution; take 5μL of the above mixed solution and drop it on the glassy carbon electrode, and dry it at room temperature to get the thin film electrode; use Hg/Hg 2 Cl 2 A three-electrode system with the electrode as the reference electrode and the Pt sheet as the counter electrode. Cyclic voltammetry was tested in 0.5 mol/L sulfuric acid and 0.5 mol/L formic acid solution deoxygenated by nitrogen. The scanning speed was 50 mV/s. See results figure 1 , figure 1 Is the cyclic voltammetry curve of the catalyst in formic acid solution, where the curve Pd/C-JM is the cyclic voltammetry curve of the commercial catalyst in formic acid solution provided in Comparative Example 1, which is represented by figure 1 It can be seen that the mass specific activity of the Pd-CoP/C-30% catalyst prepared in Example 3 is 2757.5 mA mg -1 Pd, much higher than the mass specific activity (783.1mA mg) of the commercial Pd/C catalyst (Pd/C-JM) provided in Comparative Example 1. -1 Pd).

[0075] (4) Weigh a certain amount of CoP/C-30% carrier and Pd-CoP/C-30% catalyst prepared in step (1) and step (2) to measure XRD (see figure 2 and image 3 ).

[0076] (5) Weigh a certain amount of Pd-CoP/C-30% catalyst prepared in step (2) to measure TEM (see Figure 7 ).

[0077] (6) Weigh a certain amount of the Pd-CoP/C-30% catalyst prepared in step (2) to measure XPS (see Figure 4 ).

[0078] (7) Weigh a certain amount of Pd-CoP/C-30% catalyst prepared in step (2) and add deionized water, Isopropanol solution and disperse it uniformly through ultrasound and stirring, where The mass fraction in the catalyst is 15%. The uniformly dispersed slurry is sprayed directly on the anode carbon paper TGP-H-060 (10wt% PTFE) with a sprayer. The Pd loading in the Pd-CoP/C-30% catalyst is 0.3mg cm -2 , Prepared as anode electrode.

[0079] (8) Take a certain amount of Vulcan XC-72 carbon powder and add deionized water and isopropanol to it in sequence and make it uniformly dispersed by ultrasonic and stirring. Then add a 20% PTFE solution and disperse it evenly. The uniform slurry is manually scraped onto the cathode carbon paper TGP-H-030 (20wt% PTFE), and the Vulcan XC-72 carbon powder loading is 2mg cm -2 , Dried under natural conditions to form a microporous layer. The carbon paper and the microporous layer constitute the gas diffusion layer.

[0080] (9) Weigh a certain amount of Pt black catalyst and add deionized water, Isopropanol solution and disperse it uniformly through ultrasound and stirring, where The mass fraction in the catalyst is 10%, and the uniformly dispersed slurry is sprayed on the gas diffusion layer prepared in step (8) with a sprayer. The Pt black catalyst loading is 4 mg cm -2 , Prepared as a cathode electrode.

[0081] (10) The anode prepared in step (7), The 115 membrane and the cathode prepared in step (9) are hot pressed in a hot press at 130° C. and 3 MPa for 120 seconds to obtain a membrane electrode.

[0082] The membrane electrode was installed in an active direct formic acid fuel cell, and its polarization and discharge performance were tested at 60°C. The formic acid concentration was 3M. The test results are as follows Picture 11 with Picture 12 As shown in the Pd-CoP/C-30% curve. Picture 11 The middle Pd-CoP/C-30% curve is the voltage and power curve of the membrane electrode prepared in this example when it is discharged with 3M formic acid solution at 60°C. The abscissa in the figure is the discharge current density, and the ordinate is the discharge voltage. , The secondary ordinate is the power density. Picture 12 The middle Pd-CoP/C-30% curve is the voltage curve tested when the membrane electrode prepared in this example is discharged with 3M formic acid solution at a constant voltage of 0.35V at 60°C for a long time. The abscissa in the figure is the discharge time. The ordinate is the discharge current density.

PUM

Property	Measurement	Unit
Maximum power density	149.0	mwcm-2

Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

Excellent electrochemical performance
Easy to handle

Preparation method of high-performance superlow-palladium-capacity anode electrocatalyst Pd-CoP/C of direct formic acid fuel cell

AI-Extracted Technical Summary

Problems solved by technology

Abstract

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Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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