Catalytic reduction of oxygen and hydrogen peroxide by nanoporous gold

Zeis, Roswitha; Tang, Lei; Sieradzki, Karl; Snyder, Joshua; Erlebacher, Jonah

doi:10.1016/j.jcat.2007.10.017

Cited by 236 publications

(178 citation statements)

References 21 publications

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“…Also, a doubling of the current density was observed at the np-Au electrodes. As described previously, 42 such observations are a result of oxygen reduction proceeding at planar and np-Au via different mechanisms due to the catalytic effect of defect sites present in np-Au. Oxygen reduction at np-Au electrodes proceeds via a four electron process that takes place in two steps.…”

Section: Methodsmentioning

confidence: 61%

“…Any subsequent reduction to water that may take place at planar Au occurs too slowly to be observed under the experimental conditions employed. 42 Direct comparisons between planar and np-Au systems for (a) adsorption of mixed monolayers of redox active thiols and (b) oxygen reduction are not valid due to the significant influence the electrode morphologies, in terms of defect site densities, have on the observed response. Comparisons of current densities at planar and np-Au systems for diffusion-controlled redox reactions, as a reliable method to determine the electrochemically addressable surface areas (A real ), are not valid as the overlapping diffusion zones at np-Au limit the current response.…”

Section: Methodsmentioning

confidence: 99%

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Characterization of Nanoporous Gold Electrodes for Bioelectrochemical Applications

Scanlon¹,

Salaj-Kośla²,

Belochapkine³

et al. 2011

Langmuir

101

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ABSTRACT. The high surface areas of nanostructured electrodes can provide for significantly enhanced surface loadings of electroactive materials. The fabrication and characterisation of nanoporous gold (np-Au) substrates as electrodes for bioelectrochemical applications is described.Robust np-Au electrodes were prepared by sputtering a gold-silver alloy onto a glass support and subsequent de-alloying of the silver component. Alloy layers were prepared with either a uniform or non-uniform distribution of silver and, post de-alloying, showed clear differences in morphology on characterisation with scanning electron microscopy. Redox reactions under kinetic control, in particular measurement of the charge required to strip a gold oxide layer, provided the most accurate measurements of the total electrochemically addressable electrode surface area, A real .Values of A real up to 28 times that of the geometric electrode surface area, A geo , were obtained. For diffusion controlled reactions overlapping diffusion zones between adjacent nanopores established limiting semi-infinite linear diffusion fields where the maximum current density was dependent on A geo . The importance of measuring the surface area available for the immobilisation was determined 2 using the redox protein, cyt c. The area accessible to modification by a biological macromolecule, A macro , such as cyt c was reduced by up to 40 % compared to A real , demonstrating that the confines of some nanopores were inaccessible to large macromolecules due to steric hindrances. Preliminary studies on the preparation of np-Au electrodes modified with osmium redox polymer hydrogels and Myrothecium verrucaria bilirubin oxidase (MvBOD) as a biocathode were performed; current densities of 500 A cm -2 were obtained in unstirred solutions.

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Section: Methodsmentioning

confidence: 61%

Section: Methodsmentioning

confidence: 99%

Characterization of Nanoporous Gold Electrodes for Bioelectrochemical Applications

Scanlon¹,

Salaj-Kośla²,

Belochapkine³

et al. 2011

Langmuir

101

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“…6a,b,c). This structure is similar to a metal foam [48,49] or to hierarchically sponge-like macro-/mesoporous titania [50].…”

Section: Ex Situ Surface Morphology and Effective Surface Area Measurmentioning

confidence: 79%

Evolution of self-sustained kinetic oscillations in the catalytic oxidation of propane over a nickel foil

Каичев

Teschner

Saraev

et al. 2016

Journal of Catalysis

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The evolution of self-sustained reaction-rate oscillations in the catalytic oxidation of propane over a nickel foil has been studied in situ using X-ray photoelectron spectroscopy coupled with on line mass spectrometry and gas chromatography. Changes in the effective surface area and in the catalyst morphology under reaction conditions have been examined by scanning electron microscopy and a krypton adsorption technique. It is shown that the regular kinetic oscillations arise under oxygen-lean conditions. CO, CO 2 , H 2 , H 2 O, and propylene are detected as products.The conversion of propane oscillates in a range from 1% to 23%. During the half-periods with high activity, the main reaction pathway is the partial oxidation of propane: selectivity toward CO achieves 98%. In contrast, during the half-periods with low activity, the reaction proceeds through three competitive pathways: the partial oxidation of propane, the total oxidation of propane, and the dehydrogenation of propane to propylene. The driving force for the selfsustained kinetic oscillations is the periodic reoxidation of nickel. According to the Ni2p and O1s core-level spectra measured in situ, the high-active catalyst surface is represented by metallic nickel, whereas during the inactive half-periods the catalyst surface is covered with a thick layer of NiO. The intensity of O1s spectra follows the oscillations of O 2 in the gas phase during the oxidation of propane. It is found that during the induction period before the regular oscillations appear, a rough and porous structure develops because of strong reconstruction of the catalyst surface. The thickness of the reconstructed layer is approximately 10-20 µm. This process is accompanied with at least an 80-fold increase in the effective surface area compared with a clean, non-treated nickel foil, which undoubtedly leads to a drastic increase in the number of active sites. We believe that it is the main reason for the induction period always being  Corresponding author.E-mail address: vvk@catalysis.ru (V.V. Kaichev) 2 observed before the appearance of self-sustained oscillations in the catalytic oxidation of light hydrocarbons over catalysts with a low specific surface area (single crystals, foils, or wires).Moreover, without such reconstruction, the oscillations cannot arise due to low activity of such catalysts.

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“…[29,30] Zeis et al have demonstrated the high electrocatalytic activity of nanoporous Au for the reduction of O 2 and H 2 O 2 . [31] Ohsaka and co-workers have carried out several studies on O 2 reduction on Au electrodeposited onto various substrates. [32][33][34][35][36][37][38] The resulting electrodes possessed different morphology and thus different activity in the ORR, with AuNPs with Au(100)-like crystal structure showing the highest activity.…”

Section: Introductionmentioning

confidence: 99%

Shape‐Dependent Electrocatalysis: Oxygen Reduction on Carbon‐Supported Gold Nanoparticles

et al. 2014

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Cubic, octahedral and quasi‐spherical (two different particle sizes) Au nanoparticles are synthesised and dispersed in a carbon‐black powder. The size and morphology of the Au nanocatalysts is confirmed by transmission electron microscopy and X‐ray diffraction. Au nanospheres are approximately 5 and 30 nm in diameter, whereas the size of Au octahedra and nanocubes is approximately 40–45 nm. The electrocatalytic activity of these carbon‐supported particles towards the oxygen reduction reaction (ORR) is studied in 0.5 M H2SO4 and 0.1 M KOH solutions by using the rotating‐disk‐electrode method. The specific activity (SA) for O2 reduction is measured, and the highest SA is observed for Au nanocubes supported on carbon. The highest mass activities are found for the smallest Au nanoparticles. Tafel analysis suggests that the mechanism of the ORR on shape‐controlled Au/C catalysts is the same as on bulk Au.

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Catalytic reduction of oxygen and hydrogen peroxide by nanoporous gold

Cited by 236 publications

References 21 publications

Characterization of Nanoporous Gold Electrodes for Bioelectrochemical Applications

Characterization of Nanoporous Gold Electrodes for Bioelectrochemical Applications

Evolution of self-sustained kinetic oscillations in the catalytic oxidation of propane over a nickel foil

Shape‐Dependent Electrocatalysis: Oxygen Reduction on Carbon‐Supported Gold Nanoparticles

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