Effect of Ru surface composition on the CO tolerance of Ru modified carbon supported Pt catalysts

Crabb, Eleanor M.; Ravikumar, M. K.; Thompsett, David; Hurford, M.; Rose, A. Leema; Russell, Andrea E.

doi:10.1039/b401641f

Cited by 39 publications

(46 citation statements)

References 38 publications

(60 reference statements)

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“…This result is in agreement with the report of Crabb et al [52] who found that the onset potential of carbon monoxide oxidation is lowered with the addition of a small amount of tin to platinum, and small changes in terms of shift potential are observed as quantities of tin are increased. The lower potential observed for CO oxidation with the Pt x -Sn y /C catalysts are in agreement with data reported by Colmati et al [15], although the shape of the profiles is different despite the methodology used for preparation materials being similar.…”

Section: Co Strippingsupporting

confidence: 83%

Platinum–tin/carbon catalysts for ethanol oxidation: Influence of Sn content on the electroactivity and structural characteristics

López-Suárez

Carvalho-Filho

Bueno‐López

et al. 2015

International Journal of Hydrogen Energy

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A series of Pt x -Sn y /C catalysts with different atomic ratios (x:y = 1:1, 2:1, 3:1) and diameters (~4 nm) were easily synthesized by a deposition process using formic acid as the reducing agent.Catalyst structure and chemical composition were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). XRD and SEM showed that the geometric environment was changed with Sn addition to the fcc Pt crystallites by forming a solid solution of Pt-Sn alloy phase for Pt 1 -Sn 1 /C catalyst, while for Pt 3 -Sn 1 /C and Pt 2 -Sn 1 /C, a decrease in Pt 4f binding energy was observed, and from the XPS results was attributed to charge transfer from Sn to Pt.From TEM results, it could be seen that Pt nanoparticles could be easily synthesized, even at a high metal load, without the use of expensive surfactants. The electrochemical behavior of catalysts during ethanol oxidation in acidic media was characterized and monitored in a half-cell test at room temperature by cyclic voltammetry, chronoamperometry, and anode potentiostatic polarization. The amount of Sn added affected the physical-chemical characteristics of the bimetallic catalysts; however, these catalysts did not show differences in the electrocatalytic activity towards ethanol oxidation. The presence or absence of alloy was a function of the Sn content on catalysts for the preparation method used. The behavior presented for Pt x -Sn y /C catalysts can be attributed to the so-called bifunctional mechanism, and to the electronic interaction between Pt and Sn.

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Section: Co Strippingsupporting

confidence: 83%

Platinum–tin/carbon catalysts for ethanol oxidation: Influence of Sn content on the electroactivity and structural characteristics

López-Suárez

Carvalho-Filho

Bueno‐López

et al. 2015

International Journal of Hydrogen Energy

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“…For instance, XRD measurements showed that highly active bimetallic PtRu/Vulcan catalysts, which were prepared by Ru surface modification of Pt particles via surface organometallic chemistry (SOMC), do not involve PtRu bulk alloy formation. Instead, EXAFS data indicated the formation of a surface alloy upon electrochemical reduction of the Ru modified catalyst [14]. Core-shell type structures were found even for formally bulk-alloyed nanoparticle catalysts.…”

Section: Introductionmentioning

confidence: 86%

On the Role of Reactant Transport and (Surface) Alloy Formation for the CO Tolerance of Carbon Supported PtRu Polymer Electrolyte Fuel Cell Catalysts

et al. 2006

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The role of atomic scale intermixing for the electrocatalytic activity of bimetallic PtRu anode catalysts in reformate operated polymer electrolyte fuel cells (PEFC) was investigated, exploiting the specific properties of colloid based catalyst synthesis for the selective preparation of alloyed and nonalloyed bimetallic catalysts. Three different carbon supported PtRu catalysts with different degrees of Pt and Ru intermixing, consisting of (i) carbon supported PtRu alloy particles (PtRu/C), (ii) Pt and Ru particles co-deposited on the same carbon support (Pt+Ru/C), and (iii) a mixture of carbon supported Pt and carbon supported Ru (Pt/C+Ru/C) as well as the respective monometallic Pt/C and Ru/C catalysts were prepared and characterized by electron microscopy (TEM), X-ray absorption spectroscopy, and CO stripping. Their performance as PEFC anode catalysts was evaluated by oxidation of a H 2 /2%CO gas mixture (simulated reformate) under fuel cell relevant conditions (elevated temperature, continuous reaction and controlled reactant transport) in a rotating disk electrode (RDE) set-up. The CO tolerance and H 2 oxidation activity of the three catalysts is comparable and distinctly different from that of the monometallic catalysts. The results indicate significant transport of the reactants, CO ad and/or OH ad , between Pt and Ru surface areas and particles for all three catalysts, with only subtle differences from the alloy catalyst to the physical mixture. The high activity and CO tolerance of the bimetallic catalysts, through the formation of bimetallic surfaces, is explained, e.g., by contact formation in nanoparticle agglomerates or by material transport and subsequent surface decoration/surface alloy formation during catalyst preparation, conditioning, and operation. The instability and mobility of the catalysts under these conditions closely resembles concepts in gas phase catalysis.

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“…Other pre-synthesized materials, such as Te wires and TiO 2 , have also been used as hard templates to synthesize core-shell-structured electrocatalysts, such as Au@Pt, Pd@ Pt and Ru@Pt [174][175][176]. Compared with the two-step seedmediated growth method and the one-step method; however, there has been little research into other methods of core-shell-structured electrocatalyst synthesis as a result of their complex processes [177,178].…”

Section: Principles and Development Of Wet Chemical Depositionmentioning

confidence: 99%

“…Ru@Pt core-shell structures, on the other hand, do not appear to have this issue, in which the advanced architecture of the Ru@Pt core-shell structure appears to not only protect Ru cores from dissolving, but also further decreases Pt loading compared with PtRu alloys. Recent experimental and DFT results have demonstrated that Pt monolayers coated on Ru possess substantially enhanced catalytic activities for CO oxidation through a novel pathway of weakly bonded Pt-(OH) ads on the Pt monolayer/Ru nanomaterial originating from compressive strains resulting from the apparent lattice mismatch (2.55%) between Pt and Ru [35,111,132,177,[415][416][417]. And because of these reported performance enhancements, many types of Ru@Pt core-shell-structured electrocatalysts have been synthesized by using different procedures by researchers and have been reported to produce enhanced catalytic activities for MORs [93,95,113,176,305,328,[418][419][420][421][422][423][424].…”

Section: Ru As Corementioning

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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Effect of Ru surface composition on the CO tolerance of Ru modified carbon supported Pt catalysts

Cited by 39 publications

References 38 publications

Platinum–tin/carbon catalysts for ethanol oxidation: Influence of Sn content on the electroactivity and structural characteristics

Platinum–tin/carbon catalysts for ethanol oxidation: Influence of Sn content on the electroactivity and structural characteristics

On the Role of Reactant Transport and (Surface) Alloy Formation for the CO Tolerance of Carbon Supported PtRu Polymer Electrolyte Fuel Cell Catalysts

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

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