Preparation and Structural Analysis of Carbon-Supported Co Core/Pt Shell Electrocatalysts Using Electroless Deposition Methods

Beard, Kevin D.; Borrelli, David C.; Cramer, Alison M.; Blom, Douglas A.; Zee, J. W. Van; Monnier, John R.

doi:10.1021/nn900214g

Cited by 86 publications

(74 citation statements)

References 83 publications

(95 reference statements)

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“…The extent of this effect depends on the size of the particle as well as its constituting elements and thus probably requires increased attention from the experimental side. On the other hand, Fe-Pt and Co-Pt nanoparticles with a Pt-enriched surface may be of use for catalytic purposes [76,77] taking advantage of their magnetism as another degree of freedom for further manipulation. Indeed, such bimetallic core-shell structures receive increased attention as they provide new opportunities to optimize their functional properties [78,79].…”

Section: Discussionmentioning

confidence: 99%

Competition between ordering, twinning, and segregation in binary magnetic 3d‐5d nanoparticles: A supercomputing perspective

Gruner

Entel

2011

Int J of Quantum Chemistry

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ABSTRACT:The benefit of massively parallel supercomputers for technologically relevant applications in the field of materials science is demonstrated at the example of first-principles total energy calculations of magnetic binary transition metal nanoparticles containing up to 1415 3d and 5d transition metal atoms. The simulations, which take into account structural optimizations without symmetry constraints, reveal the size-dependent evolution of the energetic order of single crystalline and multiply twinned Fe-Pt nanoparticles up to 4 nm in diameter, which are discussed as promising building blocks for future ultra-high density data recording media. Although at small diameters, multiply twinned morphologies are preferred, we can show that an energetic crossover to a single crystalline, ordered arrangement can be expected at diameters around four nanometers. The comparison with Co-Pt indicates that the contributions of the interfaces in multiply twinned structures are of similar importance as the surface and cannot be neglected especially for small particle sizes. The results imply that for Co-Pt particles segregation of Pt to the surface and the formation of a Pt-depleted subsurface layer is also dominant for nanometer-sized single crystalline particles and may help to stabilize particles with partial L1 0 order, whereas for Fe-Pt multiple twinning is the most important equilibrium mechanism for small particle sizes. Hybrid combinations of the most favorable ordering motifs, that is, L1 0 -type ordering in the particle core in combination with segregation in the outer shells, may thus lead to highly stable morphologies, which could dominate the growth process.

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Section: Discussionmentioning

confidence: 99%

Competition between ordering, twinning, and segregation in binary magnetic 3d‐5d nanoparticles: A supercomputing perspective

Gruner

Entel

2011

Int J of Quantum Chemistry

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“…Here, "large" Co cores (> 10 nm) tend to cause aggregated Pt depositions (e.g., non-continuous 3D Pt structures), whereas "small" Co cores (< 6 nm) tend to provide layer-by-layer growth, implying that the catalytic activity of Co@Pt differs with differing core sizes. And because non-continuous Pt shells lead to the quick corrosion of Co in 0.3 M H 2 SO 4 [472], the thickness of the shell greatly affects the catalytic activity of core-shell Co@Pt samples, with the monolayer Pt shell over Co core yielding the highest ORR activity [472].…”

Section: Co As Corementioning

confidence: 99%

“…And because of this, parts of the Pt atoms will exhibit similar characteristics to pure Pt, which limits Pt catalytic activity. In addition, non-continuous Pt shells will lead to the corrosion of the 3d metal cores [462,464,472]. 2.…”

Section: Merits and Demerits Of Non-noble Monometallic Coresmentioning

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 formation of alloy phase in the Pt-Co/C samples is not an expected result of the electroless deposition process. Platinum was intended to deposit as a shell over the cobalt seed particles as prior studies have shown for transition metals [17,[21][22][23]39], particularly on cobalt [20]. It is possible that the substitution of cobalt into the platinum lattice to form a Pt-Co alloy structure may be due to the simultaneous action of GD with ED, particularly the rapid ED kinetics resulting from the high initial Representative HAADF-STEM images of the samples with the lowest (Sample A) and highest (Sample D) loadings of Pt are shown in Figure 9.…”

Section: Xrd Haadf-stem and Xeds Characterization Of Pt-co/c Catalystsmentioning

confidence: 99%

“…The electroless developer bath used for the deposition of platinum was based on previous work by Beard et al [20][21][22], with the modification of substituting citrate for ethylenediamine (EN) as a stabilizing and chelating agent for Pt 4+ [23]. For the ED experiments, the aqueous bath was maintained at pH 10 and chloroplatinic acid (H 2 PtCl 6 ) used as the Pt source (existing as [PtCl 6 ] 2´c omplex in basic solution) and dimethylamine borane ((CH 3 ) 2 NH¨BH 3 , DMAB) as the reducing agent.…”

Section: Electroless Deposition Of Ptmentioning

confidence: 99%

Synthesis and Electrochemical Evaluation of Carbon Supported Pt-Co Bimetallic Catalysts Prepared by Electroless Deposition and Modified Charge Enhanced Dry Impregnation

et al. 2016

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Carbon-supported bimetallic Pt-Co cathode catalysts have been previously identified as higher activity alternatives to conventional Pt/C catalysts for fuel cells. In this work, a series of Pt-Co/C catalysts were synthesized using electroless deposition (ED) of Pt on a Co/C catalyst prepared by modified charge enhanced dry impregnation. X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM) characterization of the base catalyst showed highly dispersed particles. A basic ED bath containing PtCl 6 2´a s the Pt precursor, dimethylamine borane as reducing agent, and ethylenediamine as stabilizing agent successfully targeted deposition of Pt on Co particles. Simultaneous action of galvanic displacement and ED resulted in Pt-Co alloy formation observed in XRD and energy dispersive X-ray spectroscopy (XEDS) mapping. In addition, fast deposition kinetics resulted in hollow shell Pt-Co alloy particles while particles with Pt-rich shell and Co-rich cores formed with controlled Pt deposition. Electrochemical evaluation of the Pt-Co/C catalysts showed lower active surface but much higher mass and surface activities for oxygen reduction reaction compared to a commercial Pt/C fuel cell catalyst.

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Preparation and Structural Analysis of Carbon-Supported Co Core/Pt Shell Electrocatalysts Using Electroless Deposition Methods

Cited by 86 publications

References 83 publications

Competition between ordering, twinning, and segregation in binary magnetic 3d‐5d nanoparticles: A supercomputing perspective

Competition between ordering, twinning, and segregation in binary magnetic 3d‐5d nanoparticles: A supercomputing perspective

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

Synthesis and Electrochemical Evaluation of Carbon Supported Pt-Co Bimetallic Catalysts Prepared by Electroless Deposition and Modified Charge Enhanced Dry Impregnation

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