284 research outputs found
Quantifying electrochemical promotion of induced bipolar Pt particles supported on YSZ
Electrochemical promotion (EP) of CO oxidation is shown for the first time on induced bipolar Pt particles supported on yttria-stabilized zirconia (YSZ). These Pt particles are formed by sputter deposition of high-purity Pt metal followed by sintering. Conditions were chosen to stay below the percolation threshold of Pt particles. In-plane polarization of Pt particles results in a bipolar system and leads to the formation of a large number of galvanic cells partially or completely polarized. We have defined an equivalent number of active cells (n cell) which has been estimated from the oxygen evolution reaction as a function of the applied current on the two feed electrodes. The CO oxidation rate is measured under high vacuum conditions as a function of applied current. The use of isotopically labeled oxygen allows the discrimination of the faradaic process (16O from YSZ) from the non-faradaic process (18O from18O2) and to determine the faradaic efficiency (Î) and the rate enhancement (Ï) parameters in this bipolar system. These results mark an important step in the realization of electrochemical promotion on highly dispersed catalysts. © 2010
Investigation of the Pt/YSZ interface at low oxygen partial pressure by solid electrochemical mass spectroscopy under high vacuum conditions
The Pt/YSZ interface was investigated at low oxygen partial pressure under high vacuum (HV) conditions at 400 A degrees C. Two different electrochemical techniques were coupled to mass spectrometric gas analysis using a new solid electrochemical mass spectrometric monitoring device. Under cathodic polarization, the lack of oxygen in the gas phase induces the reduction of the YSZ solid electrolyte which acts as oxygen source for the formation of O2- ions migrating to the anode. Under anodic polarization, both platinum oxidation and oxygen evolution reaction are identified. PtO (x) is formed at both the Pt/YSZ and the Pt/gas interface according to two different mechanisms. At the Pt/YSZ interface, PtO (x) formation is an electrochemical process following a parabolic growth law, while the presence of PtO (x) at the Pt/gas interface is related to the diffusion of PtO (x) formed at the triple phase boundary towards the Pt/gas interface. It is proposed that the side oxygen evolution reaction stabilizes thermodynamically the PtO (x) diffusion toward the gas exposed interface during the anodic polarization
Optimization of Ti/Ta2O5âSnO2 electrodes and reaction parameters for electrocatalytic oxidation of methylene blue
Electrodeposited lead dioxide coatings
Lead dioxide coatings on inert substrates such as titanium and carbon now offer new opportunities for a material known for 150 years. It is now recognised that electrodeposition allows the preparation of stable coatings with different phase structures and a wide range of surface morphologies. In addition, substantial modification to the physical properties and catalytic activities of the coatings are possible through doping and the fabrication of nanostructured deposits or composites. In addition to applications as a cheap anode material in electrochemical technology, lead dioxide coatings provide unique possibilities for probing the dependence of catalytic activity on layer composition and structure (critical review, 256 references)
Preparation and characterization of Ti/SnO2-Sb electrode by Pechini's method for phenol oxidation
Electro-oxidation of cyanide on active and non-active anodes: Designing the electrocatalytic response of cobalt spinels
[EN] The feasibility of the electrochemical technologies for wastewater treatment greatly relies on the design of
efficient but inexpensive electrocatalysts. It is generally accepted that the so-called Âżnon-activeÂż anodes (like the
boron-doped diamond (BDD) or SnO2-based anodes), producing highly oxidizing hydroxyl radicals, are the most
promising candidates for pollutants abatement. In this work, the electrocatalytic performance of various cobalt
oxides, pure and doped with Cu or Au, for CNÂż oxidation has been studied and compared with that of conventional
graphite, BDD, SnO2-Sb and SnO2-Sb-Pt. The metal oxide electrodes were prepared by thermal decomposition
of the salt precursors onto Ti. For the M-doped Co3O4 electrodes, the nominal M/Co ratios were Cu/
Co=0.07Âż1.00; and Au/Co=0.05Âż0.20. The electrodes were characterized by different techniques (XRD, SEM,
EDX, XPS) and their electrocatalytic response was studied by cyclic voltammetry and galvanostatic electrolysis in
a H-type cell in aqueous 0.1M NaOH. The obtained results show that the nature of the dopant plays a key role on
the electrocatalytic behavior of cobalt spinels. Thus, while Cu catalyzes the CNÂż electro-oxidation, Au declines
it. This is explained by the fact that, unlike Au (which segregates as Au-rich particles), Cu is effectively incorporated
into the spinel structure by forming a solid solution (CuxCo3-xO4). In this solid solution, atomic scale
Cu(spinel)-CNÂż specific interactions occur to catalyze the reaction, whereas in segregated Au particles the oxidation
is hindered probably by a too-strong adsorption of cyanide and/or its inaccessibility to oxide active sites.
Electrolysis runs have revealed that ÂżactiveÂż over-saturated Cu-doped spinels (Cu/Co=1.00) exhibit higher
current efficiencies than conventional graphite and Âżnon-activeÂż BDD and SnO2-based anodes. Hence, we hereby
demonstrate that an inexpensive ÂżactiveÂż electrocatalyst can show even higher efficiency than the most powerful
BDD anode. These results highlight the significance of anode design in the application of the electrochemical
technique for wastewater treatment.Financial support from the Spanish Ministerio de Economia y Competitividad and FEDER funds (MAT2016-76595-R, IJCI-2014-20012) is gratefully acknowledgedBerenguer, R.; Quijada, C.; La Rosa-Toro, A.; MorallĂłn, E. (2019). Electro-oxidation of cyanide on active and non-active anodes: Designing the electrocatalytic response of cobalt spinels. Separation and Purification Technology. 208:42-50. https://doi.org/10.1016/j.seppur.2018.05.024S425020
InfluĂȘncia da temperatura de calcinação na resistĂȘncia Ă corrosĂŁo do eletrodo de Ti/SnO2-Sb para eletrooxidação de fenĂłis em meio de cloreto
Influence of Supporting Electrolytes on RO 16 Dye Electrochemical Oxidation Using Boron Doped Diamond Electrodes
Structural analyses of RuO2âTiO2/Ti and IrO2âRuO2âTiO2/Ti anodes used in industrial chlor-alkali membrane processes
Insight on the fundamentals of advanced oxidation processes. Role and review of the determination methods of reactive oxygen species
Advanced oxidation processes (AOPs) have known increased application to treat wastewaters containing recalcitrant compounds that are hardly degraded by conventional technologies. AOPs are characterized by the formation of strong oxidants such as hydroxyl radicals, superoxide anions, hydroperoxyl radicals and singlet oxygen, which react with the contaminant, contributing to its degradation. This paper provides an overview of the determination methods of reactive oxygen species, ROS, in the application of AOPs; the methods developed in the available literature for the detection and quantification of ROS are reviewed as a first step in the assessment and detailed description of the mechanisms involved in the oxidation reactions, focusing on the critical analysis of the main strengths and weaknesses presented by the probe molecules employed in the evaluated studies.This research was supported by the Ministry of Economy and Competitiveness (MINECO/SPAIN) and European Regional Development Fund (ERDF) under the project CTQ2011-25262
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