Electrochemical and Chemical Treatment Methods for Enhancement of Oxygen Reduction Reaction Activity of Pt Shell-Pd Core Structured Catalyst

Aoki, Naoya; Inoue, Hideo; Shirai, Akira; Higuchi, Shunya; Matsui, Yoshihiko; Doi, Takayuki; Inaba, Masaaki

doi:10.1016/j.electacta.2017.05.054

Cited by 25 publications

(30 citation statements)

References 36 publications

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“…The electrochemical surface area (ECSA) of the Pt/Pd/C catalyst was determined from total charge for the wave of hydrogen desorption on the CV (0.05−0.4 V) using a conversion factor of 210 μC cm −2 -Pt. 29,53,54 LSV was measured from 0.05 to 1.2 V in 0.1 mol dm −3 HClO 4 under an O 2 atmosphere at a disk rotation rate of 1600 rpm. The scan rate of LSVs was fixed at 10 mV s −1 .…”

Section: Methodsmentioning

confidence: 99%

“…We developed a pretreatment method using electrochemical oxidation/ reduction cycles to enhance ORR mass activity of the Pt/ Pd/C catalyst, while minimizing ECSA decay. 29 Hereafter, this protocol for the electrochemical pretreatment is referred to as HAP. This HAP was used to elevate the activity of the ORR of the Pt/Pd/C catalyst in this study.…”

Section: = × −mentioning

confidence: 99%

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Creation of a Highly Active Pt/Pd/C Core–Shell-Structured Catalyst by Synergistic Combination of Intrinsically High Activity and Surface Decoration with Melamine or Tetra-(tert-butyl)-tetraazaporphyrin

et al. 2020

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A Pt/Pd/C core−shell-structured catalyst with an extraordinarily high activity of 3625 A g −1 -Pt at 0.9 V versus a reversible hydrogen electrode (RHE) for the oxygen reduction reaction (ORR) was created by a synergistic combination of intrinsically high activity and surface decoration with melamine or tetra-(tert-butyl)-tetraazaporphyrin (tBuTAP). The intrinsically highly active Pt/Pd/C catalyst with an ORR mass activity of ca. 1000 A g −1 -Pt at 0.9 V versus RHE was synthesized by a direct displacement reaction method, and the activity was activated to ca. 1500 A g −1 -Pt via a high activation protocol (HAP) (a rectangular potential cycling of 0.05−1.0 V vs an RHE conducted in 0.1 mol dm −3 HClO 4 under an Ar atmosphere at 80 °C). The ORR activities of the Pt/Pd/C catalysts were further increased by surface decoration with melamine or tBuTAP, and the mass activity of ORR of the catalyst activated by an HAP was enhanced to 3625 A g −1 -Pt at 0.9 V versus RHE via the melamine decoration, which is about 11-fold that of a reference Pt/C catalyst (320 A g −1 -Pt). Cyclic voltammograms, linear sweep voltammograms, and CO stripping voltammograms indicated that the surface decoration further destabilized the OH species (OH ad ) adsorbed on the Pt shell and suppressed the formation of oxide on the Pt shell, which could explain the extraordinary enhancement of ORR activity. We present guidelines for creating Pt-based catalysts with extraordinarily high activity for the ORR by the synergistic combination of the intrinsically active Pt-based catalyst [improvement from the inside of Pt nanoparticles (NPs)] and surface decoration (improvement from the outside of Pt NPs).

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Section: Methodsmentioning

confidence: 99%

Section: = × −mentioning

confidence: 99%

Creation of a Highly Active Pt/Pd/C Core–Shell-Structured Catalyst by Synergistic Combination of Intrinsically High Activity and Surface Decoration with Melamine or Tetra-(tert-butyl)-tetraazaporphyrin

et al. 2020

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“…Especially, the reduction of the amount of Pt catalyst is important because it accounts for about 46% of the system cost. In previous research, Pt alloying catalysts [ 4 , 5 , 6 , 7 , 8 ] and Pt core-shell structural catalysts [ 9 , 10 , 11 , 12 , 13 ] were studied. Furthermore, research is being conducted on new catalysts to completely replace Pt catalysts [ 14 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of the Catalyst Layer Structure Formed by Inkjet Coating Printer on PEFC Performance

Tamaki

Sugiura

2021

Polymers

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In this study, we investigated the influence of the Catalyst-Layer (CL) structure on Polymer Electrolyte Fuel Cell (PEFC) performance using an inkjet coating printer, and we especially focused on the CL thickness and the electrode area. In order to evaluate the influence of CL thickness, we prepared four Membrane Electrode Assemblies (MEAs), which have one, four, five and six CLs, respectively, and evaluated it by an overpotential analysis. As a result, the overpotentials of an activation and a diffusion increased with the increase of thickness of CL. From Energy Dispersive X-ray spectroscopy (EDX) analysis, because platinum twines most ionomers and precipitates, the CL separates into a layer of platinum with a big grain aggregate ionomer and the mixing layer of platinum and ionomer during the catalyst ink drying process. Consequently, the activation overpotential increased because the three-phase interface was not able to be formed sufficiently. The gas diffusivity of the multilayer catalyst electrode was worse than that of a single layer MEA. The influence of the electrode area was examined by two MEAs with 1 and 9 cm2 of electrode area. As a result, the diffusion overpotential of 9 cm2 MEA was worse than 1 cm2 MEA. The generated condensate was multiplied and moved to the downstream side, and thereafter it caused the flooding/plugging phenomena.

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“…Currently, PEFCs are already commercialized for low-temperature working conditions, especially in small-scale transportation systems such as fuel cell vehicles (FCVs) and residential cogeneration systems. − However, several problems remain unsolved, preventing the large-scale use of PEFCs. One major obstacle to the commercialization of FCVs is the high cost of Pt cathode catalysts used for the oxygen reduction reaction (ORR), resulting in inefficient reaction kinetics and degradation effects under the strong acidic conditions. − Therefore, high performance, high durability, and less expensive catalysts are expected to widen the use of PEFC devices.…”

Section: Introductionmentioning

confidence: 99%

Effect of Temperature on Oxygen Reduction Reaction Kinetics for Pd Core–Pt Shell Catalyst with Different Core Size

Liu

Uchiyama

Yamamoto

et al. 2020

ACS Appl. Energy Mater.

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The oxygen reduction reaction (ORR) activity and the coverage of oxide species over a Pd core−Pt shell catalyst on carbon support (Pt/Pd/C) with various Pd core sizes (2.3, 4.3, and 8.0 nm) were investigated in the temperature range from 25 to 60 °C and compared with a Pt/C catalyst (TEC10V30E, Tanaka Kikinzoku Kogyo). The apparent rate constant (k app ) of Pt/Pd/C increased with increasing core size at 25 °C. However, k app of Pt/Pd/C started to decrease at 50−60 °C, while that of Pt/C behaved according to the general Arrhenius equation. Eventually, the 2.3 nm core showed the highest k app at 60 °C, and the 8.0 nm core was almost the same as that of Pt/C. According to the electrochemical measurements, the coverage of oxide species on Pt/Pd/C was quite smaller than that of Pt/C. However, it increased dramatically with increasing temperature from 25 to 60 °C. Among the Pt/Pd/C, the 8.0 nm core showed the most obvious oxide coverage increase at 60 °C, which was almost identical to that of Pt/C. In contrast, the 2.3 nm core showed the lowest oxide coverage at 60 °C, which was expected to be the cause of the largest k app . Operando X-ray absorption spectroscopy indicated that the Pt−Pt bond length in Pt/Pd/C was shorter than that in the Pt/C at 25 °C due to compressive surface strain from the Pd core, which is the reason why Pt/Pd/C has higher activity than Pt/C. On the other hand, as Pd has a thermal expansion coefficient higher than that of Pt, Pt/Pd/C showed a Pt−Pt bond length larger than that of Pt/C at 60 °C. A longer Pt−Pt bond length extension was observed at 60 °C in the 8.0 nm core compared to that in the other catalysts.

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Electrochemical and Chemical Treatment Methods for Enhancement of Oxygen Reduction Reaction Activity of Pt Shell-Pd Core Structured Catalyst

Cited by 25 publications

References 36 publications

Creation of a Highly Active Pt/Pd/C Core–Shell-Structured Catalyst by Synergistic Combination of Intrinsically High Activity and Surface Decoration with Melamine or Tetra-(tert-butyl)-tetraazaporphyrin

Creation of a Highly Active Pt/Pd/C Core–Shell-Structured Catalyst by Synergistic Combination of Intrinsically High Activity and Surface Decoration with Melamine or Tetra-(tert-butyl)-tetraazaporphyrin

Influence of the Catalyst Layer Structure Formed by Inkjet Coating Printer on PEFC Performance

Effect of Temperature on Oxygen Reduction Reaction Kinetics for Pd Core–Pt Shell Catalyst with Different Core Size

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