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Preparation of a platinum electrocatalyst by coaxial pulse arc plasma deposition

View Article: PubMed Central - PubMed

ABSTRACT

We have developed a new method of preparing Pt electrocatalysts through a dry process. By coaxial pulse arc plasma deposition (CAPD), highly ionized metal plasma can be generated from a target rod without any discharged gases, and Pt nanoparticles can be deposited on a carbon support. The small-sized Pt nanoparticles are distributed over the entire carbon surface. From transmission electron microscopy (TEM), the average size of the deposited Pt nanoparticles is estimated to be 2.5 nm, and their size distribution is narrow. Our electrocatalyst shows considerably improved catalytic activity and stability toward methanol oxidation reaction (MOR) compared with commercially available Pt catalysts such as Pt black and Pt/carbon (PtC). Inspired by its very high efficiency toward MOR, we also measured the catalytic performance for oxygen reduction reaction (ORR). Our PtC catalyst shows a better performance with half-wave potential of 0.87 V, which is higher than those of commercially available Pt catalysts. The higher performance is also supported by a right-shifted onset potential. Our preparation is simple and could be applied to other metallic nanocrystals as a novel platform in catalysis, fuel cells and biosensors.

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(a) ORR polarization curves of a RDE modified with PtC-CAPD, PtC-5% and PtC-20%. The plots were obtained in O2-saturated KOH (0.1 M) at a rotation rate of 1600 rpm with a scan rate of 10 mV s−1. (b) ORR polarization curves of PtC-CAPD at different rotation rates (from 100 rpm to 2000 rpm) in O2-saturated KOH (0.1 M) with a scan rate of 10 mV s−1. (c) The Koutecky–Levich (K–L) plots of PtC-CAPD at various potentials. RHE stands for reversible hydrogen electrode.
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Figure 5: (a) ORR polarization curves of a RDE modified with PtC-CAPD, PtC-5% and PtC-20%. The plots were obtained in O2-saturated KOH (0.1 M) at a rotation rate of 1600 rpm with a scan rate of 10 mV s−1. (b) ORR polarization curves of PtC-CAPD at different rotation rates (from 100 rpm to 2000 rpm) in O2-saturated KOH (0.1 M) with a scan rate of 10 mV s−1. (c) The Koutecky–Levich (K–L) plots of PtC-CAPD at various potentials. RHE stands for reversible hydrogen electrode.

Mentions: Inspired by its very high efficiency toward MOR, the catalytic performance toward ORR was analyzed in order to get more evidence for practical application in fuel cell technology. The sluggish oxygen reduction and the low efficiency of catalysts are usually the two main problems for fuel cell applications. Here, our Pt catalyst was evaluated and compared with other carbon-supported Pt catalysts (PtC-5% and PtC-20%). The typical polarization plots of each sample are displayed in figure 5(a). All samples show the oxygen reduction activity and the diffusion-controlled current plateaus. Compared to the two commercially available PtCs, our catalyst shows a better performance with a half-wave potential of 0.87 V, which is 0.09 and 0.03 V more positive than those of PtC-5% and PtC-20% catalysts, respectively. The higher performance was also supported by the higher onset potential. To determine the ORR electron-transfer pathway, the polarization curves of PtC were recorded at different rotation rates. An increase of the limiting diffusion current densities as a function of the rotation rate was obtained (figure 5(b)). The corresponding Koutecky–Levich (K–L) plots are shown in figure 5(c); the electron transfer number of 3.88 suggests that our PtC sample catalyzes the ORR mainly through a four-electron process [45, 46].


Preparation of a platinum electrocatalyst by coaxial pulse arc plasma deposition
(a) ORR polarization curves of a RDE modified with PtC-CAPD, PtC-5% and PtC-20%. The plots were obtained in O2-saturated KOH (0.1 M) at a rotation rate of 1600 rpm with a scan rate of 10 mV s−1. (b) ORR polarization curves of PtC-CAPD at different rotation rates (from 100 rpm to 2000 rpm) in O2-saturated KOH (0.1 M) with a scan rate of 10 mV s−1. (c) The Koutecky–Levich (K–L) plots of PtC-CAPD at various potentials. RHE stands for reversible hydrogen electrode.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 5: (a) ORR polarization curves of a RDE modified with PtC-CAPD, PtC-5% and PtC-20%. The plots were obtained in O2-saturated KOH (0.1 M) at a rotation rate of 1600 rpm with a scan rate of 10 mV s−1. (b) ORR polarization curves of PtC-CAPD at different rotation rates (from 100 rpm to 2000 rpm) in O2-saturated KOH (0.1 M) with a scan rate of 10 mV s−1. (c) The Koutecky–Levich (K–L) plots of PtC-CAPD at various potentials. RHE stands for reversible hydrogen electrode.
Mentions: Inspired by its very high efficiency toward MOR, the catalytic performance toward ORR was analyzed in order to get more evidence for practical application in fuel cell technology. The sluggish oxygen reduction and the low efficiency of catalysts are usually the two main problems for fuel cell applications. Here, our Pt catalyst was evaluated and compared with other carbon-supported Pt catalysts (PtC-5% and PtC-20%). The typical polarization plots of each sample are displayed in figure 5(a). All samples show the oxygen reduction activity and the diffusion-controlled current plateaus. Compared to the two commercially available PtCs, our catalyst shows a better performance with a half-wave potential of 0.87 V, which is 0.09 and 0.03 V more positive than those of PtC-5% and PtC-20% catalysts, respectively. The higher performance was also supported by the higher onset potential. To determine the ORR electron-transfer pathway, the polarization curves of PtC were recorded at different rotation rates. An increase of the limiting diffusion current densities as a function of the rotation rate was obtained (figure 5(b)). The corresponding Koutecky–Levich (K–L) plots are shown in figure 5(c); the electron transfer number of 3.88 suggests that our PtC sample catalyzes the ORR mainly through a four-electron process [45, 46].

View Article: PubMed Central - PubMed

ABSTRACT

We have developed a new method of preparing Pt electrocatalysts through a dry process. By coaxial pulse arc plasma deposition (CAPD), highly ionized metal plasma can be generated from a target rod without any discharged gases, and Pt nanoparticles can be deposited on a carbon support. The small-sized Pt nanoparticles are distributed over the entire carbon surface. From transmission electron microscopy (TEM), the average size of the deposited Pt nanoparticles is estimated to be 2.5 nm, and their size distribution is narrow. Our electrocatalyst shows considerably improved catalytic activity and stability toward methanol oxidation reaction (MOR) compared with commercially available Pt catalysts such as Pt black and Pt/carbon (PtC). Inspired by its very high efficiency toward MOR, we also measured the catalytic performance for oxygen reduction reaction (ORR). Our PtC catalyst shows a better performance with half-wave potential of 0.87 V, which is higher than those of commercially available Pt catalysts. The higher performance is also supported by a right-shifted onset potential. Our preparation is simple and could be applied to other metallic nanocrystals as a novel platform in catalysis, fuel cells and biosensors.

No MeSH data available.