Pt-Au@Pt core-shell structure fuel cell cathode catalyst and preparation method thereof

A fuel cell cathode, core-shell structure technology, applied in battery electrodes, chemical instruments and methods, physical/chemical process catalysts, etc., can solve the problems of low coverage, low catalytic activity, low Pt coverage on the catalyst surface, etc. The effect of improving quality and activity, enriching resources, and solving the problem of catalyst resources

Inactive Publication Date: 2013-05-08

WUHAN UNIV

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Problems solved by technology

In addition, although the method of underpotential deposition of Cu monolayer on the surface of Au nanoparticles and then Pt replacement can make Pt uniformly dispersed on the Au surface, but the research shows that ...

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Abstract

The invention discloses a Pt-Au@Pt core-shell structure fuel cell cathode catalyst and a preparation method thereof. The Pt-Au@Pt core-shell structure fuel cell cathode catalyst consists of a conductive carrier and Pt-Au@Pt core-shell structure nanoparticles. The preparation method comprises the following steps of: reducing a gold compound by using sodium borohydride to obtain Au nanoparticles, and loading the Au particles on the surface of a carbon carrier to obtain Au/C; and putting Au/C in a platinum compound water solution to obtain loaded-type Pt/Au alloy nanoparticles after Pt is subjected to spontaneous reductive deposition on the Au surface, depositing a Cu atom monolayer on the surface of the Pt-Au alloy nanoparticles by using an underpotential deposition method and then displacing the Cu atom monolayer with Pt to obtain the Pt-Au@Pt core-shell structure fuel cell cathode catalyst. The catalyst prepared by using the preparation method disclosed by the invention is high in catalytic activity and stability and low in cost relative to a pure Pt catalyst; and the preparation method is simple and convenient, mild in condition and easy to operate and can be used for solving the problem that a core-shell structure catalyst prepared by using a conventional chemical reduction method is high in Pt agglomeration degree on the surface and a catalyst prepared by using a single underpotential deposition method is low in Pt coverage degree on the surface.

Application Domain

Cell electrodesMetal/metal-oxides/metal-hydroxide catalysts

Technology Topic

Gold CompoundsAlloy nanoparticle +7

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Examples

Experimental program(4)
Effect test(1)

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[0033] The preparation method includes the steps: 1) In the mixed solution of the gold compound and sodium citrate, sodium borohydride is added to reduce the gold compound to obtain Au nanoparticles. Then the Au particles are loaded on the surface of the carbon support to obtain carbon-supported Au, which is recorded as Au/C.

[0034] 2) Place Au/C in an aqueous solution of platinum compound without adding a reducing agent to allow Pt to be spontaneously reduced on the Au surface. After centrifugation and drying, the supported Pt-Au alloy nanoparticles are obtained, where the reduction temperature is 20-100 ℃, the concentration of platinum compound is 10 -5 mol/L ~10 -2 mol/L.

[0035] 3) Coating the Pt-Au alloy nanoparticles obtained by spontaneous reduction on the surface of the electrode, and obtaining a Cu atomic layer through the method of under-potential deposition, and the Cu prepared by this method is called UPD Cu. The electrode is immersed in the replacement solution to make Pt replace the Cu atomic layer to obtain a Pt-AuPt core-shell structured nanocatalyst.

[0036]

Example Embodiment

[0037] Example 1

[0038] 1) Pt-AuPt/C core-shell structure catalyst Pt 0.2 AuPt 0.15 /C preparation

[0039] In the mixed solution of chloroauric acid and sodium citrate, add sodium borohydride to reduce the chloroauric acid, stir evenly, after the solution turns purple-red, add the conductive carrier, after immersing for 36 hours at room temperature, centrifugation and vacuum drying to obtain the carbon carrier Au, namely Au/C;. Put Au/C at a concentration of 10 -4 mol/L ~10 -3 mol/L potassium chloroplatinate aqueous solution, stir for 24 hours at 25°C to obtain Pt 0.2 Au/C alloy. Pt 0.2 The Au/C alloy is coated on the surface of the electrode, the electrode potential is controlled, and Cu is deposited at a constant potential under the Cu under-potential deposition potential to obtain an electrode of Cu atomic layer. The electrode with UPD Cu monolayer is immersed in the replacement liquid potassium chloroplatinate solution for 30 minutes, so that Pt replaces the Cu atoms on the electrode surface, and a Pt atomic layer is formed on the electrode surface to obtain Pt 0.2 AuPt 0.15 /C core-shell structure nano catalyst, the total mass of Pt and Au metal is about 22wt% of the catalyst. The resulting catalyst Pt 0.2 AuPt 0.15 The particle size range of /C is 2~5nm.

[0040] 2) Test Pt-AuPt/C core-shell structure catalyst Pt 0.2 AuPt 0.15 /C cathode performance and stability

[0041] Contain Pt on the surface 0.2 AuPt 0.15 The electrode of the /C catalyst is inserted into the electrolyte as a working electrode. Test the catalyst Pt separately with a three-electrode system 0.2 AuPt 0.15 /C and Pt/C electrochemical performance, the specific test is as follows: use 0.1mol/L perchloric acid as electrolyte, 27°C water bath temperature control, large platinum plate as counter electrode, saturated calomel electrode as reference For ratio electrode, place the reference electrode in the salt bridge, and insert the other end of the salt bridge into the electrolytic cell and approach the working electrode through the tip of the capillary. Test Pt at 50mV/s scanning speed in Ar saturated electrolyte 0.2 AuPt 0.15 /C and Pt/C hydrogen absorption and desorption characteristic curve, in O 2 5mV/s scanning speed in saturated electrolyte, electrode speed 1600rpm test catalyst Pt 0.2 AuPt 0.15 The catalytic activity of /C and Pt/C on oxygen reduction reaction. The test results show that the area activity of Pt/C is 0.14 mA/cm at 0.9V (vs reversible hydrogen electrode) 2 , The mass activity is 100 mA/mg, Pt 0.2 AuPt 0.15 /C area activity 0.66 mA/cm 2 , The mass activity is 680 mA/mg, compared with Pt/C, Pt 0.1 AuPt 0.17 The area activity of /C is increased by nearly 5 times, and the mass activity is increased by nearly 7 times.

[0042] In O 2 Sweep 10,000 cycles of cyclic voltammetry in the potential range of 0.6V-1.1V (vs reversible hydrogen electrode) in saturated electrolyte to test the stability of the catalyst. The test results show that: Pt 0.2 AuPt 0.15 After 10,000 cycles of cyclic voltammetry, the electrochemical active area of the /C catalyst hardly decays, and the half-wave potential of the polarization curve of the oxygen reduction reaction is almost the same as the half-wave potential of the polarization curve of the initial oxygen reduction reaction. figure 1 with figure 2 Shown, indicating that Pt 0.2 AuPt 0.15 The catalytic activity of /C hardly decays; while the electrochemical active area of the Pt/C catalyst decays to 48% of the initial after 10,000 cycles of cyclic voltammetry, the half-wave potential of the oxygen reduction reaction polarization curve shifts negatively by 34mV, such as image 3 with Figure 4 As shown, the activity of Pt/C is greatly attenuated.

[0043] The chloroauric acid used in this embodiment can be replaced by potassium chloroauric acid, the potassium chloroplatinite used can be replaced by potassium chloroplatinate, chloroplatinic acid, sodium chloroplatinite, and sodium chloroplatinite. The conductive carbon black used can be replaced by activated carbon, For carbon nanotube replacement, the replacement liquid potassium chloroplatinite solution used can be replaced by potassium chloroplatinate solution, sodium chloroplatinate solution, chloroplatinic acid solution, sodium chloroplatinite solution without affecting the obtained catalyst Pt 0.2 AuPt 0.15 /C performance.

[0044]

Example Embodiment

[0045] Example 2

[0046] 1) Pt-AuPt/C core-shell structure catalyst Pt 0.1 AuPt 0.17 /C preparation

[0047] In the mixed solution of chloroauric acid and sodium citrate, add sodium borohydride to reduce the chloroauric acid, stir evenly, after the solution turns purple-red, add the conductive carrier, after immersing at room temperature for 48 hours, centrifugation and vacuum drying to obtain the carbon carrier Au, namely Au/C; put Au/C at a concentration of 10 -5 mol/L ~10 -4 mol/L potassium chloroplatinate aqueous solution, stirred at 30°C for 12 hours to obtain Pt 0.1 Au/C alloy. Pt 0.1 The Au/C alloy is coated on the surface of the electrode, the electrode potential is controlled, and Cu is deposited at a constant potential under the Cu under-potential deposition potential to obtain an electrode of Cu atomic layer. The electrode with UPD Cu monolayer is soaked in the replacement liquid potassium chloroplatinate solution for 15 minutes, so that Pt replaces the Cu atoms on the electrode surface, and the Pt atomic layer is formed on the electrode surface to obtain Pt 0.1 AuPt 0.17 /C core-shell structure nano catalyst, the total mass of Pt and Au metal is about 20wt% of the catalyst. The resulting catalyst Pt 0.1 AuPt 0.17 The particle size range of /C is 2~5nm.

[0048] 2) Test Pt-AuPt/C core-shell structure catalyst Pt 0.1 AuPt 0.17 /C cathode performance

[0049] Contain Pt on the surface 0.1 AuPt 0.17 The electrode of the /C catalyst is inserted into the electrolyte as a working electrode. Test the catalyst Pt separately with a three-electrode system 0.1 AuPt 0.17 And Pt/C electrochemical performance, the specific test is as follows: use 0.1mol/L perchloric acid as electrolyte, 27°C water bath temperature control, large platinum plate as counter electrode, saturated calomel electrode as reference electrode , Place the reference electrode in the salt bridge, insert the other end of the salt bridge into the electrolytic cell and approach the working electrode through the tip of the capillary. Test Pt at 50mV/s scanning speed in Ar saturated electrolyte 0.1 AuPt 0.17 /C and Pt/C hydrogen absorption and desorption characteristic curve, in O 2 5mV/s scanning speed in saturated electrolyte, electrode speed 1600rpm test catalyst Pt 0.1 AuPt 0.17 The catalytic activity of /C and Pt/C on oxygen reduction reaction. The test results show that the area activity of Pt/C is 0.14 mA/cm at 0.9V (vs reversible hydrogen electrode) 2 , The mass activity is 100 mA/mg, Pt 0.1 AuPt 0.17 /C area activity 0.62 mA/cm 2 , The mass activity is 560 mA/mg, compared with Pt/C, Pt 0.1 AuPt 0.17 The area activity of /C is increased by 4-5 times, and the mass activity is increased by nearly 6 times.

[0050] The chloroauric acid used in this embodiment can be replaced by potassium chloroauric acid, the potassium chloroplatinite used can be replaced by potassium chloroplatinate, chloroplatinic acid, sodium chloroplatinite, and sodium chloroplatinite. The conductive carbon black used can be replaced by activated carbon, For carbon nanotube replacement, the replacement liquid potassium chloroplatinite solution used can be replaced by potassium chloroplatinate solution, sodium chloroplatinate solution, chloroplatinic acid solution, sodium chloroplatinite solution without affecting the obtained catalyst Pt 0.1 AuPt 0.17 /C performance.

[0051]

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PUM

Property	Measurement	Unit
Particle size range	2.0 ~ 5.0	nm
tensile		MPa
Particle size		Pa
strength	10

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AI-Extracted Technical Summary

Problems solved by technology

Abstract

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Example Embodiment

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Example Embodiment

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Description & Claims & Application Information

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