Composition-Controlled PtCo Alloy Nanocubes with Tuned Electrocatalytic Activity for Oxygen Reduction

Choi, Sang‐Il; Lee, Su‐Un; Kim, Woo Youn; Choi, Ran; Hong, Kootak; Nam, Ki-Min; Han, Sang Woo; Park, Joon-Taik

doi:10.1021/am301824w

Cited by 109 publications

(85 citation statements)

References 54 publications

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“…Considering the fact that XPS measurement of the core level is very useful to evaluate D-band shifts because of its high correlation with the valence band XPS, [34] the XPS results unambiguously indicate that the D-band centers of the Pt/NC catalysts downshifted compared to that of the Pt/C. As the oxygen binding energy (E OB ) [35,36] the XPS results are in good agreement with those of the electrochemical measurements.…”

Section: Resultssupporting

confidence: 64%

“…ECSA values of the catalysts were calculated by integrating the charges in the H UPD region of the CVs. [36] Furthermore, the ORR current density of the Pt/NC 2.0 catalyst at 0.9 V after the durability test decreased by only 9 % (from 3.05 to 2.79 mA cm This indicates that enhanced stability could also be achieved by incorporating nitrogen into the Pt/C catalyst. It has been reported that the nitrogen functionalities on the support usually improve the stability of the supported catalyst particles because of the strong interaction between the support and particles.…”

Section: Resultsmentioning

confidence: 95%

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Nitrogen‐Doped Pt/C Electrocatalysts with Enhanced Activity and Stability toward the Oxygen Reduction Reaction

et al. 2013

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Recently, nitrogen‐doped carbon materials have proved to be effective catalytic platforms for the oxygen reduction reaction (ORR). Despite the recent synthetic advances for the preparation of nitrogen‐incorporated carbon materials, the low‐temperature and water‐based synthesis of nitrogen‐doped carbon materials has rarely been explored due to the difficulties in nitrogen‐doping under such mild conditions. Here, nitrogen‐doped Pt/C (Pt/NC) catalysts are prepared using a facile, low‐temperature, aqueous‐phase method. Hydrazine treatment of a Pt/C catalyst successfully yields Pt/NC with controlled nitrogen content. The as‐prepared Pt/NC catalysts exhibit enhanced electrocatalytic activity and stability toward ORR in comparison to nitrogen‐free Pt/C, and their ORR activities are highly dependent on the level of nitrogen‐doping. The Pt/NC catalyst containing 2.0 at % nitrogen results in the largest improvement of ORR activity.

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Section: Resultssupporting

confidence: 64%

Section: Resultsmentioning

confidence: 95%

Nitrogen‐Doped Pt/C Electrocatalysts with Enhanced Activity and Stability toward the Oxygen Reduction Reaction

et al. 2013

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“…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][15][16] shape (or size), [17][18][19][20][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.…”

mentioning

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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“…To address these issues, great efforts have been devoted to constructing Pt‐based alloys by introducing a non‐precious metal (M) . Compared with pure Pt, the PtM alloys usually exhibit a higher catalytic activity and stability, and their enhanced performance is generally attributed to the synergetic effects of electronic (Pt d ‐band vacancy) and geometric (Pt lattice strain) structure modulation, which can alter Pt d ‐band center …”

Section: Introductionmentioning

confidence: 99%

Methanol Oxidation Reaction Performance on Graphene‐Supported PtAg Alloy Nanocatalyst: Contrastive Study of Electronic and Geometric Effects Induced from Ag Doping

et al. 2018

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In Pt‐based alloy catalyst, the electrocatalytic performance is highly related to the Pt d‐band center, whose position can be modulated by the synergetic interaction of electronic and geometric effects. In this study, graphene‐supported PtAg (PtAg/graphene) alloy nanocatalyst was prepared by a facile galvanic replacement reaction. Due to the introduction of Ag component, the PtAg/graphene exhibits a higher specific/mass activity (1.48 mA cm–2, 580 mA mgPt–1) and better CO tolerance (CO stripping potential: 0.45 V vs. Ag/AgCl) than those of commercial Pt/C catalyst (0.86 mA cm–2, 270 mA mgPt–1, 0.50 V vs. Ag/AgCl) when being applied for catalyzing methanol oxidation reaction (MOR). On the basis of component and structure characterization, the PtAg alloy catalyst model was constructed, and first‐principles density function theory calculation was applied to study the relative influence of electronic and geometric effects on the Pt d‐band center and CO binding energy, respectively. It is found that the electronic effect, i. e. the charge transfer from Ag to Pt, is the decisive factor to enhance the electrocatalytic performance of PtAg alloy towards MOR.

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Composition-Controlled PtCo Alloy Nanocubes with Tuned Electrocatalytic Activity for Oxygen Reduction

Cited by 109 publications

References 54 publications

Nitrogen‐Doped Pt/C Electrocatalysts with Enhanced Activity and Stability toward the Oxygen Reduction Reaction

Nitrogen‐Doped Pt/C Electrocatalysts with Enhanced Activity and Stability toward the Oxygen Reduction Reaction

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

Methanol Oxidation Reaction Performance on Graphene‐Supported PtAg Alloy Nanocatalyst: Contrastive Study of Electronic and Geometric Effects Induced from Ag Doping

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Composition-Controlled PtCo Alloy Nanocubes with Tuned Electrocatalytic Activity for Oxygen Reduction

Cited by 109 publications

References 54 publications

Nitrogen‐Doped Pt/C Electrocatalysts with Enhanced Activity and Stability toward the Oxygen Reduction Reaction

Nitrogen‐Doped Pt/C Electrocatalysts with Enhanced Activity and Stability toward the Oxygen Reduction Reaction

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

Methanol Oxidation Reaction Performance on Graphene‐Supported PtAg Alloy Nanocatalyst: Contrastive Study of Electronic and Geometric Effects Induced from Ag Doping

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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