Effect of Particle Size of Platinum and Platinum-Cobalt Catalysts on Stability Against Load Cycling

Matsutani, Koichi; Hayakawa, Katsuichiro; Tada, Tomofumi

doi:10.1595/147106710x523698

Cited by 70 publications

(61 citation statements)

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“…• C, 23,26,34 we intend to clarify the effect of crystal structure on the ORR activity and durability for the Pt 3 Co alloy catalysts with the nearly identical size distribution. To suppress the excessive agglomeration of particles (< ca.…”

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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“…The recent work by Matsutani et al reported particle size effects of the Pt and PtCo catalyst performance in MEAs and suggested that the MEAs with cathodes containing 4-5 nm Pt particles and 7-8 nm PtCo particles were the most stable. These two sizes were the largest of the catalyst particles studied [30]. These catalysts were found to be more stable when heat treated to a higher temperature.…”

Section: Introductionmentioning

confidence: 90%

Effect of Particle Size and Operating Conditions on Pt3Co PEMFC Cathode Catalyst Durability

et al. 2015

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Abstract:The initial performance and decay trends of polymer electrolyte membrane fuel cells (PEMFC) cathodes with Pt3Co catalysts of three mean particle sizes (4.9 nm, 8.1 nm, and 14.8 nm) with identical Pt loadings are compared. Even though the cathode based on 4.9 nm catalyst exhibited the highest initial electrochemical surface area (ECA) and mass activity, the cathode based on 8.1 nm catalyst showed better initial performance at high currents. Owing to the low mass activity of the large particles, the initial performance of the 14.8 nm Pt3Co-based electrode was the lowest. The performance decay rate of the electrodes with the smallest Pt3Co particle size was the highest and that of the largest Pt3Co particle size was lowest. Interestingly, with increasing number of decay cycles (0.6 to 1.0 V, 50 mV/s), the relative improvement in performance of the cathode based on 8.1 nm Pt3Co over the 4.9 nm Pt3Co increased, owing to better stability of the 8.1 nm catalyst. The electron OPEN ACCESSCatalysts 2015, 5 927 microprobe analysis (EMPA) of the decayed membrane-electrode assembly (MEA) showed that the amount of Co in the membrane was lower for the larger particles, and the platinum loss into the membrane also decreased with increasing particle size. This suggests that the higher initial performance at high currents with 8.1 nm Pt3Co could be due to lower contamination of the ionomer in the electrode. Furthermore, lower loss of Co from the catalyst with increased particle size could be one of the factors contributing to the stability of ECA and mass activity of electrodes with larger cathode catalyst particles. To delineate the impact of particle size and alloy effects, these results are compared with prior work from our research group on size effects of pure platinum catalysts. The impact of PEMFC operating conditions, including upper potential, relative humidity, and temperature on the alloy catalyst decay trends, along with the EMPA analysis of the decayed MEAs, are reported.

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“…doi:10.1016/j.apcatb.2011.10.007 electrocatalyst durability in PEMFCs, however, fewer studies have been reported. Matsutani et al [25] observed an improved stability of Pt against PEMFC load cycling as the Pt particle size increased from 2-3 nm to 4-5 nm after heat treatment, but detailed mechanism for the stability improvement was not addressed. Based on the literature, a comprehensive investigation with well-defined preparation and evaluation methodologies regarding Pt particle size effect on the activity for ORR and the durability of Pt/C in PEMFCs is yet to be conducted.…”

Section: Introductionmentioning

confidence: 99%

Effect of particle size on the activity and durability of the Pt/C electrocatalyst for proton exchange membrane fuel cells

Zhang

Zhong

et al. 2012

Applied Catalysis B: Environmental

162

110

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a b s t r a c tCarbon supported Pt (Pt/C) with various average particle sizes ranging from sub 3 nm to 6.5 nm were in situ prepared and characterized at the cathode of proton exchange membrane fuel cells (PEMFCs). A clear Pt particle size effect on both the catalytic activity for oxygen reduction reaction (ORR) and the durability of the electrocatalyst was revealed. With the Pt particle size increase, both the surface specific activity and the electrochemical stability of Pt/C improved; however, the mass specific activity of Pt/C is balanced by the electrochemical surface area loss. The reduced occupation of corner and edge atoms on the Pt surface during the Pt particle size increase is believed to weaken the adsorption of the oxygenated species on Pt, and thereafter releases more available active sites for ORR and also renders the Pt surface a stronger resistance against potential cycling. It is therefore proposed that by designing the Pt microstructure with more face atoms on the surface, cathode electrocatalyst with both improved activity and enhanced durability would be developed for PEMFCs.

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Effect of Particle Size of Platinum and Platinum-Cobalt Catalysts on Stability Against Load Cycling

Cited by 70 publications

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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

Effect of Particle Size and Operating Conditions on Pt3Co PEMFC Cathode Catalyst Durability

Effect of particle size on the activity and durability of the Pt/C electrocatalyst for proton exchange membrane fuel cells

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Effect of Particle Size of Platinum and Platinum-Cobalt Catalysts on Stability Against Load Cycling

Cited by 70 publications

References 0 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

Effect of Particle Size and Operating Conditions on Pt3Co PEMFC Cathode Catalyst Durability

Effect of particle size on the activity and durability of the Pt/C electrocatalyst for proton exchange membrane fuel cells

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Product

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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