Temperature-dependence of oxygen reduction activity at a platinum electrode in an acidic electrolyte solution investigated with a channel flow double electrode

Wakabayashi, Noriaki; Takeichi, Masayuki; Itagaki, Masayuki; Uchida, Hiroyuki; Watanabe, Masahiro

doi:10.1016/j.jelechem.2004.08.013

Cited by 185 publications

(218 citation statements)

References 29 publications

(56 reference statements)

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“…45 Because the contribution of the two-electron-reduction of O 2 to generate H 2 O 2 to the overall reaction was small enough to be neglected, as shown later, we calculated an apparent rate constant k app (per unit active area, shown in Eq. 1) 37 to compare the area-specific activity for the ORR measured at temperatures from 30 to 80…”

Section: Resultsmentioning

confidence: 99%

Oxygen Reduction Activity and Durability of Ordered and Disordered Pt₃Co Alloy Nanoparticle Catalysts at Practical Temperatures of Polymer Electrolyte Fuel Cells

Yano¹,

Arima²,

Watanabe³

et al. 2017

J. Electrochem. Soc.

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We have succeeded in preparing ordered-and disordered-Pt 3 Co nanoparticles supported on carbon black (CB), with the nearly identical particle size distribution, by the nanocapsule method with heat-treatment at high temperatures. The temperature dependences of the oxygen reduction reaction (ORR) activities at two kinds of Pt 3 Co/CB catalysts were examined in O 2 -saturated 0.1 M HClO 4 solution by the multi-channel flow double electrode (M-CFDE) technique. For the ordered-Pt 3 Co/CB, the apparent rate constant k app (per unit active area) for the ORR increased with elevation of the temperature up to 65 • C and stabilized at nearly the same value as that for commercial c-Pt/CB at 80 • C, due to a severe dealloying of the Co component in the hot acid solution. In contrast, the k app values at the disordered-Pt 3 Co/CB were higher than those of the ordered-Pt 3 Co/CB over the whole temperature range from 30 • C to 80 • C. The disordered-Pt 3 Co/CB also exhibited higher stability than the ordered-Pt 3 Co/CB for both an accelerated durability test (ADT, by standard potential step cycles between 0.6 V and 1. The polymer electrolyte fuel cell (PEFC) is anticipated to be one of the most promising, clean, and energy-efficient power sources for fuel cell vehicles (FCVs) and stationary cogeneration systems (FCCGs). In 2014, a strategic roadmap for hydrogen and fuel cells was formulated by the Ministry of Economy, Trade, and Industry (METI) of Japan and was revised in 2016.1 For the large scale commercialization of both FCVs and FC-CGs in its Phase 1, it is necessary to reduce the system cost while maintaining the performance and durability. At the present stage, however, the use of substantial amounts of costly Pt cathode catalysts supported on carbon (Pt/C) is unavoidable to decrease the large overpotential for the oxygen reduction reaction (ORR). Hence, the development of the cathode catalysts having both high activity for the ORR and high durability is quite important. To improve the ORR activity, Pt-based catalysts alloyed with non-precious metal such as Fe, 2-6 Co, 2,4,7-11 and Ni, 2-13 have been investigated intensively. For nano-sized Pt-M alloy catalysts (Pt-M/C), the kinetically-controlled area-specific activity j k for the ORR was enhanced by ca. 2∼7 times compared to that of pure Pt. The enhancement factor has been found to depend on various properties of alloy nanoparticles, e.g., composition, 4,14-16 shape (or size), 17-21 and crystal structure. [22][23][24][25][26][27][28][29] For example, the values of j k for Pt-Co alloys showed a maximum at the atomic ratio of Pt/Co = 3. 4,5,14 It has been reported that the electronic structure of the Pt skin layer formed on Pt-M alloys could change with the composition of the underlying alloy, reaching a maximum at the optimum alloy composition or alloying metal species M. 24,[30][31][32] Because the surface is not perfectly covered with uniform Pt skin layer, j k often decreases appreciably by dealloying of M during the operation of PEFCs or electrochemical measurements...

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Section: Resultsmentioning

confidence: 99%

Oxygen Reduction Activity and Durability of Ordered and Disordered Pt₃Co Alloy Nanoparticle Catalysts at Practical Temperatures of Polymer Electrolyte Fuel Cells

Yano¹,

Arima²,

Watanabe³

et al. 2017

J. Electrochem. Soc.

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“…, we evaluated the kinetically-controlled current I k at a given potential. 22,23 By extrapolating the plots of I ¹1 (inverse of the observed current) vs U m ¹1/3 to U m ¹1/3 = 0 (infinite mass transport rate), the value of the I k was calculated. The kineticallycontrolled mass activity MA k (I k divided by the initially loaded mass of Pt, m Pt ) at 0.85 V and area-specific activity j k (MA k divided by the ECA) were calculated.…”

Section: Characterization Of Pt 2al -Pt-m/c Catalystsmentioning

confidence: 99%

Oxygen Reduction Reaction Activity of Carbon-Supported Pt-Fe, Pt-Co, and Pt-Ni Alloys with Stabilized Pt-Skin Layers

et al. 2016

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We have prepared carbon-supported Pt-M (M = Fe, Co, and Ni) alloy nanoparticles with uniform size and composition as cathode catalysts for polymer electrolyte fuel cells. In order to protect the underlying Pt-M alloy from dealloying and maintain high mass activity for the oxygen reduction reaction (ORR), two atomic layers of Ptskin (Pt 2AL ) were formed on the Pt-M nanopartcicles. By means of various types of analysis, including X-ray diffraction (XRD), inductively coupled plasma mass analysis (ICP-MS), thermogravimetry (TG), and transmission electron microscopy (TEM), the formation of monodisperse Pt 2AL -Pt-M/C was confirmed. The kinetically-controlled ORR activities (mass activity, MA k , and area-specific activity, j k ) for the ORR at Nafion ® -coated Pt 2AL -Pt-M/C catalysts in O 2 -saturated 0.1 M HClO 4 solution were evaluated by the use of a multi-channel flow double electrode cell at 65°C. It was found that the initial value of MA k at Pt 2AL -PtNi/C was the highest, i.e., 3.3 times higher than that at a commercial catalyst, carbon-supported Pt (c-Pt/C). In contrast, the Pt 2AL -PtCo/C catalyst exhibited superior durability, so that dealloying was almost entirely suppressed, together with a great mitigation of the particle agglomeration after applying 10 4 cycles of potential steps between 0.6 V and 1.0 V.

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“…1a, where O 2 diffuses through thin (nm scale) ionomer or solution film to obtain large O 2 flux/limiting current. Conversely, hydrodynamic methods such as channel flow dual electrode (CFDE), 7,8 rotating disk electrode and rotating ring disk electrodes (RDE or RRDE) 9 methods operate on the principle of controllable limiting currents and fall under the second classification. In these cases, O 2 diffusion to catalyst surface may be modeled as illustrated in Fig.…”

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confidence: 99%

“…Furthermore, the potential, temperature, pressure, electrolyte type, acid grade, and concentration at which the SA is reported vary between groups making comparison non-trivial. We have collected/extracted and presented ORR SA values for poly-Pt reported in the literature 4,7,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] along with key measurement parameters in Fig. 2.…”

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Oxygen Reduction Reaction Measurements on Platinum Electrocatalysts Utilizing Rotating Disk Electrode Technique

Shinozaki

Zack

Richards

et al. 2015

J. Electrochem. Soc.

290

340

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The rotating disk electrode (RDE) technique is being extensively used as a screening tool to estimate the activity of novel PEMFC electrocatalysts synthesized in lab-scale (mg) quantities. Discrepancies in measured activity attributable to glassware and electrolyte impurity levels, as well as conditioning, protocols and corrections are prevalent in the literature. The electrochemical response to a broad spectrum of commercially sourced perchloric acid and the effect of acid molarity on impurity levels and solution resistance were also assessed. Our findings reveal that an area specific activity (SA) exceeding 2.0 mA/cm 2 (20 mV/s, 25 • C, 100 kPa, 0.1 M HClO 4 ) for polished poly-Pt is an indicator of impurity levels that do not impede the accurate measurement of the ORR activity of Pt based catalysts. After exploring various conditioning protocols to approach maximum utilization of the electrochemical area (ECA) and peak ORR activity without introducing catalyst degradation, an investigation of measurement protocols for ECA and ORR activity was conducted. Down-selected protocols were based on the criteria of reproducibility, duration of experiments, impurity effects and magnitude of pseudo-capacitive background correction. Statistical reproducibility of ORR activity for poly-Pt and Pt supported on high surface area carbon was demonstrated.

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Temperature-dependence of oxygen reduction activity at a platinum electrode in an acidic electrolyte solution investigated with a channel flow double electrode

Cited by 185 publications

References 29 publications

Oxygen Reduction Activity and Durability of Ordered and Disordered Pt₃Co Alloy Nanoparticle Catalysts at Practical Temperatures of Polymer Electrolyte Fuel Cells

Oxygen Reduction Activity and Durability of Ordered and Disordered Pt₃Co Alloy Nanoparticle Catalysts at Practical Temperatures of Polymer Electrolyte Fuel Cells

Oxygen Reduction Reaction Activity of Carbon-Supported Pt-Fe, Pt-Co, and Pt-Ni Alloys with Stabilized Pt-Skin Layers

Oxygen Reduction Reaction Measurements on Platinum Electrocatalysts Utilizing Rotating Disk Electrode Technique

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Temperature-dependence of oxygen reduction activity at a platinum electrode in an acidic electrolyte solution investigated with a channel flow double electrode

Cited by 185 publications

References 29 publications

Oxygen Reduction Activity and Durability of Ordered and Disordered Pt3Co Alloy Nanoparticle Catalysts at Practical Temperatures of Polymer Electrolyte Fuel Cells

Oxygen Reduction Activity and Durability of Ordered and Disordered Pt3Co Alloy Nanoparticle Catalysts at Practical Temperatures of Polymer Electrolyte Fuel Cells

Oxygen Reduction Reaction Activity of Carbon-Supported Pt-Fe, Pt-Co, and Pt-Ni Alloys with Stabilized Pt-Skin Layers

Oxygen Reduction Reaction Measurements on Platinum Electrocatalysts Utilizing Rotating Disk Electrode Technique

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Oxygen Reduction Activity and Durability of Ordered and Disordered Pt₃Co Alloy Nanoparticle Catalysts at Practical Temperatures of Polymer Electrolyte Fuel Cells

Oxygen Reduction Activity and Durability of Ordered and Disordered Pt₃Co Alloy Nanoparticle Catalysts at Practical Temperatures of Polymer Electrolyte Fuel Cells