Oxygen reduction at platinum modified gold electrodes

Brussel, Maarten Van; Kokkinidis, G.; Hubin, Annick; Buess‐Herman, C.

doi:10.1016/s0013-4686(03)00529-2

Cited by 94 publications

(89 citation statements)

References 20 publications

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“…Such hollow and porous structures have drawn interest as they can shift plasmon resonances compared with those of solid nanoparticles 5,10 , may provide nanoscale containers for biomedical applications such as diagnostics and drug delivery 11 , are of use as contrast enhancement agents in optical imaging such as optical coherence 12 , photoacoustic tomography 13,14 , and are found to be highly active in catalysis [15][16][17][18][19][20] and electrocatalysis 21,22 . The galvanic replacement reaction is critical in the advanced two-step synthesis of fuel cell electrocatalysts with reduced precious metal loadings, limited to a thin surface layer or even a monolayer on top of less expensive metal nanoparticles [23][24][25][26][27][28][29][30][31][32][33] . The electrocatalysts obtained either via the transmetalation of an underpotentially deposited 23,26,28 or electrodeposited 27,[29][30][31][32][33] monolayer or thin layer of a less precious metal by a precious metal upon immersion into a complex solution of Pt, Pd or Au ions 23,[26][27][28][29][30][31][32]…”

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confidence: 99%

“…The galvanic replacement reaction is critical in the advanced two-step synthesis of fuel cell electrocatalysts with reduced precious metal loadings, limited to a thin surface layer or even a monolayer on top of less expensive metal nanoparticles [23][24][25][26][27][28][29][30][31][32][33] . The electrocatalysts obtained either via the transmetalation of an underpotentially deposited 23,26,28 or electrodeposited 27,[29][30][31][32][33] monolayer or thin layer of a less precious metal by a precious metal upon immersion into a complex solution of Pt, Pd or Au ions 23,[26][27][28][29][30][31][32][33] , or by partial galvanic replacement 24,25 exhibit enhanced activity compared to the most active Pt catalysts [23][24][25][26][27][28][29][30][31][32][33] .…”

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confidence: 99%

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In situ liquid-cell electron microscopy of silver–palladium galvanic replacement reactions on silver nanoparticles

et al. 2014

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Galvanic replacement reactions provide an elegant way of transforming solid nanoparticles into complex hollow morphologies. Conventionally, galvanic replacement is studied by stopping the reaction at different stages and characterizing the products ex situ. In situ observations by liquid-cell electron microscopy can provide insight into mechanisms, rates and possible modifications of galvanic replacement reactions in the native solution environment. Here we use liquid-cell electron microscopy to investigate galvanic replacement reactions between silver nanoparticle templates and aqueous palladium salt solutions. Our in situ observations follow the transformation of the silver nanoparticles into hollow silverpalladium nanostructures. While the silver-palladium nanocages have morphologies similar to those obtained in ex situ control experiments the reaction rates are much higher, indicating that the electron beam strongly affects the galvanic-type process in the liquid-cell. By using scavengers added to the aqueous solution we identify the role of radicals generated via radiolysis by high-energy electrons in modifying galvanic reactions.

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confidence: 99%

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In situ liquid-cell electron microscopy of silver–palladium galvanic replacement reactions on silver nanoparticles

et al. 2014

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“…10) in which sacrificial Cu metal is first applied as a UPD monolayer onto a Pd substrate and Sphere/10 nm/monolayer [35,301] subsequently displaced spontaneously by a Pt monolayer in a PtCl 4 2− solution [270]. This procedure has also been used by other researchers to deposit Pt monolayers onto Au colloids [280,281]. Other sacrificial metal layers such as Pb and Ag can also be used for depositing M 2 monolayers [274] and more specific examples of the UPD are collected in Table 6.…”

Section: Principles and Development Of Electrodepositionmentioning

confidence: 99%

Core–Shell-Structured Low-Platinum Electrocatalysts for Fuel Cell Applications

Wang

Luo

et al. 2018

Electrochem. Energ. Rev.

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Pt-based catalysts are the most efficient catalysts for low-temperature fuel cells. However, commercialization is impeded by prohibitively high costs and scarcity. One of the most effective strategies to reduce Pt loading is to deposit a monolayer or a few layers of Pt over other metal cores to form core-shell-structured electrocatalysts. In core-shell-structured electrocatalysts, the compositions of the core can be divided into five classes: single-precious metallic cores represented by Pd, Ru, and Au; singlenon-precious metallic cores represented by Cu, Ni, Co, and Fe; alloy cores containing 3d, 4d or 5d metals; and carbide and nitride cores. Of these, researchers have found that carbide and nitride cores can yield tremendous advantages over alloy cores in terms of cost and promotional activities of Pt shells. In addition, desirable shells with reasonable thicknesses and compositions have been recognized to play a dominant role in electrocatalytic performances. And recently, researchers have also found that the catalytic activity of core-shell-structured catalysts is dependent on the binding energy of the adsorbents, which is determined by the d-band center of Pt. The shifting of this d-band center in turn is mainly affected by strain and electronic effects, which can be adjusted by adjusting core compositions and shell thicknesses of catalysts. In the development of these core-shell structures, optimal synthesis methods are of primary concern because they directly determine the practical application potential of the resulting electrocatalysts. And in this article, the principles behind core-shell-structured low-Pt electrocatalysts and the developmental progresses of various synthesis methods along with the traits of each type of core and its effects on Pt shell catalytic activities are discussed. In addition, perspectives on this type of catalyst are discussed and future research directions are proposed.

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“…The high values (theoretical value: 120 mV dec −1 [35]) are most likely due to the same effects that are described above. The shift in the Tafel slope due to the transition from the low to the high current density regime is commonly observed, and can be explained by different effects: (i) A change of the charge-transfer coefficient [37,38], (ii) different reactant adsorption mechanisms (Temkin vs. Langmuir mechanism for low and high current regimes, respectively) [35,39], (iii) a change in surface coverage with oxygen-containing species [40], and (iv) further porosity related diffusion effects [41,42]. …”

Section: Oxygen Reduction Activitymentioning

confidence: 99%

Improved stability of mesoporous carbon fuel cell catalyst support through incorporation of TiO2

Bauer

Song

Ignaszak

et al. 2010

Electrochimica Acta

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The electrochemical stability of Pt deposited on mesoporous carbon, which was either applied in its unmodified state or coated with 20 wt% TiO 2 , was investigated by cyclic voltammetry in N 2 purged 0.5 M sulfuric acid. XRD analysis revealed that TiO 2 was present in the anatase phase. The mean Pt particle diameter was ∼6 and ∼4 nm for mesoporous carbon with and without TiO 2 , respectively. Pt supported on TiO 2 modified substrates was more stable than Pt supported on conventional mesoporous carbon when subjected to 1000 cycles in the potential range from 0.05 to 1.25 V vs. RHE. This was evident from the observation that the support with TiO 2 retained ∼53% of the electrochemically active surface area relative to the state observed after 100 cycles, whereas ∼33% of the active area remained in the case without TiO 2 . The oxygen reduction mass activity was identical for both fresh samples (i.e., 18 A g −1 Pt). After 1000 cycles the mass activity decreased to 10 A g −1 Pt for the case without TiO 2 , whereas with TiO 2 the deactivation was minor; i.e., the mass activity after 1000 cycles was 17 A g .

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Oxygen reduction at platinum modified gold electrodes

Cited by 94 publications

References 20 publications

In situ liquid-cell electron microscopy of silver–palladium galvanic replacement reactions on silver nanoparticles

In situ liquid-cell electron microscopy of silver–palladium galvanic replacement reactions on silver nanoparticles

Core–Shell-Structured Low-Platinum Electrocatalysts for Fuel Cell Applications

Improved stability of mesoporous carbon fuel cell catalyst support through incorporation of TiO2

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