Modification of platinum surfaces by spontaneous deposition: Methanol oxidation electrocatalysis

MacDonald, J.P.; Gualtieri, B.; Runga, N.; Téliz, Erika; Zinola, C.F.

doi:10.1016/j.ijhydene.2008.09.008

Cited by 27 publications

(11 citation statements)

References 54 publications

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“…Such an effect has been noted for the electrooxidation of methanol using various electrode materials: initially Pt anodes − and then more complex alloys − and nanoparticles. − Surface studies on Pt anodes showed that Pt is poisoned by adsorbed CO, which is formed as an intermediate during the electrooxidation process. ,− Combining Pt with a second metal improved the anode behavior, and systems utilizing the bimetallic RuPt anode proved to be particularly effective. − This effect has been attributed to the “bi-functional mechanism” initially proposed by Watanabe and Motoo, in which Pt sites are responsible for the binding and dehydrogenation of methanol while Ru sites activate water through formation of Ru–oxo intermediates, which are then involved in conversion of surface-bound CO to CO 2 . − …”

Section: Introductionmentioning

confidence: 93%

Iron and Ruthenium Heterobimetallic Carbonyl Complexes as Electrocatalysts for Alcohol Oxidation: Electrochemical and Mechanistic Studies

2011

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Carbonyl-containing Ru and Fe heterobimetallic complexes were prepared and tested as electrocatalysts for the oxidation of methanol and ethanol. GC analysis of the electrolyte solution during bulk electrolysis indicated that CpRu(CO)(μ-I)(μ-dppm)PtI2 (1), CpFe(CO)(μ-I)(μ-dppm)PtI2 (2), and CpRu(CO)(μ-I)(μ-dppm)PdI2 (3) were catalysts for the electrooxidation of methanol and ethanol, while CpFe(CO)(μ-I)(μ-dppm)PdI2 (4), CpRu(CO)I(μ-dppm)AuI (5), and CpFe(CO)I(μ-dppm)AuI (6) did not function as catalysts. The oxidation of methanol resulted in two- and four-electron oxidation to formaldehyde and formic acid, respectively, followed by condensation with unreacted methanol to yield dimethoxymethane and methyl formate as the observed products. The oxidation of ethanol afforded 1,1′-diethoxyethane as a result of two-electron oxidation to acetaldehyde and condensation with excess ethanol. FTIR analysis of the headspace gases during the electrochemical oxidation of methanol indicated formation of CO2. Isotopic labeling experiments demonstrated that the CO2 resulted from oxidation of the CO ligand instead of complete oxidation of CH3OH.

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Section: Introductionmentioning

confidence: 93%

Iron and Ruthenium Heterobimetallic Carbonyl Complexes as Electrocatalysts for Alcohol Oxidation: Electrochemical and Mechanistic Studies

2011

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“…The nature of the Ru species formed on Pt by spontaneous deposition was determined using commercial Pt/C [32] and only oxidized Ru species (RuO 2 and RuO x H y ) were found. Considering that the atomic hydrogen is not adsorbed on the Ru species [7], the Pt coverage (θ) in the Pt-Ru(Cu)/C electrocatalyst can be estimated according to the following equation [33]:…”

Section: Charge Of Cu Electrodeposition In the Synthesis Sequence Imentioning

confidence: 99%

Effects of the Electrodeposition Time in the Synthesis of Carbon-Supported Pt(Cu) and Pt-Ru(Cu) Core-Shell Electrocatalysts for Polymer Electrolye Fuel Cells

et al. 2016

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Pt(Cu)/C and Pt-Ru(Cu)/C electrocatalysts with core-shell structure supported on Vulcan Carbon XC72R have been synthesized by potentiostatic deposition of Cu nanoparticles on the support, galvanic exchange with Pt and spontaneous deposition of Ru species. The duration of the electrodeposition time of the different species has been modified and the obtained electrocatalysts have been characterized using electrochemical and structural techniques. The High Resolution Transmission Electron Microscopy (HRTEM), Fast Fourier Transform (FFT) and Energy Dispersive X-ray (EDX) microanalyses allowed the determining of the effects of the electrodeposition time on the nanoparticle size and composition. The best conditions identified from Cyclic Voltammetry (CV) corresponded to onset potentials for CO and methanol oxidation on Pt-Ru(Cu)/C of 0.41 and 0.32 V vs. the Reversible Hydrogen Electrode (RHE), respectively, which were smaller by about 0.05 V than those determined for Ru-decorated commercial Pt/C. The CO oxidation peak potentials were about 0.1 V smaller when compared to commercial Pt/C and Pt-Ru/C. The positive effect of Cu was related to its electronic effect on the Pt shells and also to the generation of new active sites for CO oxidation. The synthesis conditions to obtain the best performance for CO and methanol oxidation on the core-shell Pt-Ru(Cu)/C electrocatalysts were identified. When compared to previous results in literature for methanol, ethanol and formic acid oxidation on Pt(Cu)/C catalysts, the present results suggest an additional positive effect of the deposited Ru species due to the introduction of the bifunctional mechanism for CO oxidation.

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“…MOR measurements revealed a maximum catalytic activity for Ru coverages about 0.10–0.40 on Ru-modified Pt (111) surfaces . The modified surfaces were mainly analyzed by Auger electron spectroscopy (AES), ,, scanning tunneling microscopy (STM), ,,, and X-ray photoelectron spectroscopy (XPS). ,, Ru nanodeposits of 2–5 nm were detected as a result of the deposition step. ,,, XPS measurements showed the existence of Ru oxides as the main compounds in the modified electrocatalyst, ,,, which could be subject to further partial or complete reduction through a potential treatment , or remain on the electrocatalyst surface as nonreducible oxides. , …”

Section: Introductionmentioning

confidence: 99%

“…The spontaneous deposition has been mainly employed to modify the Pt low-index monocrystal surfaces to improve the MOR performance. − ,,− The deposition step has been typically performed using RuCl 3 as metal precursor and HClO 4 as acidic electrolyte, since sulfate/bisulfate anions are strongly adsorbed on Pt sites causing the inhibition of the process . MOR measurements revealed a maximum catalytic activity for Ru coverages about 0.10–0.40 on Ru-modified Pt (111) surfaces .…”

Section: Introductionmentioning

confidence: 99%

Structural Characterization of Ru-Modified Carbon-Supported Pt Nanoparticles Using Spontaneous Deposition with CO Oxidation Activity

et al. 2012

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The modification of carbon-supported Pt nanoparticles, high performance (HP) 20% Pt on Vulcan XC-72 carbon black (Pt/C electrocatalyst), by spontaneous deposition of Ru species is examined employing electrochemical and structural techniques. Thin-layer electrodes were prepared by applying aqueous catalyst inks of Pt/C on glassy carbon (GC) disks. Ru deposition was carried out by immersion of the prepared electrode in deaerated RuCl 3 / HClO 4 solutions. The subsequent cyclic voltammetry experiments of the modified electrocatalysts (Ru(Pt)/C) were performed in 0.5 M H 2 SO 4 to determine the Ru coverage and the electroactive surface. CO stripping voltammetry showed the promotional effect of Ru(Pt)/C for the CO oxidation compared to Pt/C. The structural characterization of the modified electrocatalysts was performed by transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analyses, fast Fourier transform (FFT), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). TEM observations revealed no appreciable signals of Ru agglomerates, and EDX confirmed the regular incorporation of Ru species to the nanoparticles. XRD analyses showed the characteristic profile of the Pt face-centered cubic (FCC) structure and the absence of crystalline Ru or Ru oxides. The application of the Williamson−Hall models indicated that Ru incorporation did not significantly affect the internal strain of the Pt nanoparticles, the increase of the crystallite size being attributed to an epitaxial growth of the Ru deposit. XPS measurements reported the presence of nonreducible RuO 2 and hydrous RuO 2 (RuO x H y ) as the main Ru species in Ru(Pt)/C, the hydrous species justifying the promotional effect for the CO oxidation.

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Modification of platinum surfaces by spontaneous deposition: Methanol oxidation electrocatalysis

Cited by 27 publications

References 54 publications

Iron and Ruthenium Heterobimetallic Carbonyl Complexes as Electrocatalysts for Alcohol Oxidation: Electrochemical and Mechanistic Studies

Iron and Ruthenium Heterobimetallic Carbonyl Complexes as Electrocatalysts for Alcohol Oxidation: Electrochemical and Mechanistic Studies

Effects of the Electrodeposition Time in the Synthesis of Carbon-Supported Pt(Cu) and Pt-Ru(Cu) Core-Shell Electrocatalysts for Polymer Electrolye Fuel Cells

Structural Characterization of Ru-Modified Carbon-Supported Pt Nanoparticles Using Spontaneous Deposition with CO Oxidation Activity

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