Papers by Oumarou SAVADOGO
Batteries, Fuel Cells, and Energy Conversion-Using Multi-Pseudocriteria and Fuzzy Outranking Relation Analysis for Material Selection of Bipolar Plates for PEFCs
Highly corrosion and wear-resistant NiW–SiC–CeO2 composite coating
Canadian Metallurgical Quarterly
ChemInform Abstract: Fermi Level Pinning of Semiconductor Electrodes in Aqueous and Non Aqueous Electrolytes: Influence of the Modification of the Electrode Surface
ChemInform, 1989
The photoelectrochemical behavior of several semiconductors (n‐ and p‐GaAs, n‐ and p‐InP, n‐ and ... more The photoelectrochemical behavior of several semiconductors (n‐ and p‐GaAs, n‐ and p‐InP, n‐ and p‐Si, and n‐GaP) modified with H4SiW12O40·nH2O is studied.
Rare Metals, 2017
Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-d (BSCF) is one of the most active cathode materials and shows si... more Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-d (BSCF) is one of the most active cathode materials and shows significant hydration effect suggesting possible proton conductivity. In this study, the performance of BSCF cathode on a protonconducting BaZr 0.1 Ce 0.7 Y 0.2 O 3-d (BZCY) electrolyte with silver and gold current collectors was determined. The electrochemical characteristics of the symmetrical and anode-supported cell with diluted silver electrode, silver current collector or gold current collector on BSCF electrode were compared. The significant result is that, although the diluted silver electrode itself shows poor operation stability, the silver current collector has strong electrocatalytic contribution to the BSCF cathode performance on the proton-conducting electrolyte, leading to higher cell performance than that with the gold current collector.
Effect of ethylene glycol on morphology, crystallinity, and electrochemical properties of LiFePO4/C in lithium-ion batteries
Journal of Applied Electrochemistry, 2015
Various amounts of ethylene glycol (EG) were used during the preparation of LiFePO4/C composite b... more Various amounts of ethylene glycol (EG) were used during the preparation of LiFePO4/C composite by hydrothermal method. The effects of EG on the structure, morphology, and the electrochemical performance of LiFePO4/C were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, surface area measurement, and electrochemical testing methods. The results showed that the ratio of the EG/water of the reaction medium for the electrode preparation has significant effects on the morphology and the crystallinity of the particles. The results also showed that the LiFePO4/C prepared with the optimized EG/water ratio (7/93) exhibited the best electrochemical performance. In particular, this electrode exhibited the best specific discharge capacity of 168.8 mAh g−1 at 0.1 C rate because of its uniform particle distribution, its large specific surface area, and its best crystallinity which is favorable for high Li-ion diffusion during redox reaction.
Improving the Activity and Stability of PdSn Catalyst for Oxygen Reduction by Heat Treatment
ECS Transactions, 2014
Carbon-supported PdSn catalysts were synthesized (ratio of about Pd:Sn = 1:1) by the NaBH4 reduct... more Carbon-supported PdSn catalysts were synthesized (ratio of about Pd:Sn = 1:1) by the NaBH4 reduction method for the oxygen reduction reaction (ORR) in HClO4 solution. The carbon support surface was previously activated with a sensitizing and activating pre-treatment. The as-prepared PdSn catalyst was then heat treated at 300 ºC in H2/N2 (3vol.% H2). The PdSn catalysts were characterized by SEM/EDX, XRD and TEM before and after the heat treatment. The electrochemical activity towards ORR was examined by cyclic and rotating disk electrode measurements and compared with that of Pd. The ORR catalytic activity of PdSn heat treated catalyst was about 25 and 4 times higher than that of as-prepared and Pd catalyst, respectively. Accelerated stability test (AST) by repetitive potential cycling indicated that PdSn heat treated was very stable in electrochemical environment.
Photoélectrochimie de GaAs(n): mécanisme de réduction de l'hexacyanoferrate (III) à une électrode de GaAs(n) en milieu aqueux
Bulletin de la Société Chimique de France, 1983
Donnees sur le mecanisme de la reduction du titre. Mise en evidence de l'influence de la pres... more Donnees sur le mecanisme de la reduction du titre. Mise en evidence de l'influence de la presence des etats de surface sur les caracteristiques I-V par l'apparition d'un courant supplementaire. La diminution du courant cathodique sous eclairement, en presence d'ions hexacyanoferrate (II) a pu etre interpretee par un mecanisme d'oxydation par les porteurs p par l'intermediaire de la bande de valence
Investigation of some new palladium alloys catalysts for the oxygen reduction reaction in an acid medium
Active palladium-based alloys catalysts without platinum for the Oxygen Reduction Reaction (ORR) ... more Active palladium-based alloys catalysts without platinum for the Oxygen Reduction Reaction (ORR) in an acid medium were shown for the first time. The catalysts were fabricated by sputtering method on a glassy carbon support and their electrochemical characteristics for the ORR were determined at 300C in sulphuric acid. with and without methanol. It was demonstrated that the base voltammograms (CVs) of Pd-Co alloys did not show significant change in the shape or size during the whole measurements procedure . Furthermore the Pd-Co alloy CV were found to be completely different from those of Pd and Co alone and they never changed to become more Pd-like or Co-like. The Pd-Co alloy catalysts are stable under the applied experimental conditions and no leaching out of the alloying Co atoms takes place. It was further demonstrated that an improvement of, at least, 250 mV in ORR over-voltage could be obtained if a Pd-Co28% catalyst is used instead of Pt for PEFC or acid Solid Polymer Electrolyser Applications. When compared to platinum, a significant improvement of the ORR was obtained on non-optimised Pd-alloys in an acid medium containing methanol. The interesting properties of the Pd-alloys for the ORR were attributed to an appropriate electronic stabilisation of the alloying element atom in the alloy which may prevent its corrosion and which allows the enhancement of its catalytic activity due to a bi-functional and/or co-catalytic behaviour of the alloying element.
International Journal of Hydrogen Energy, 1995
The electro-catalytic activity for the hydrogen evolution reaction (h.e.r.) in an alkaline electr... more The electro-catalytic activity for the hydrogen evolution reaction (h.e.r.) in an alkaline electrolyte on palladium dispersed in carbon electrodes (Pd(C)), which were electro-activated with and without SiW,,O:, (STA), was investigated. The best h.e.r. performances were observed on Pd(C) electroactivated with STA. These electrodes were characterized by X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The improved h.e.r. electro-catalytic activity observed on Pd(C) electro-activated with STA was attributed both to surface chemical composition and to the increased active surface area of these electrodes,.
Development of Molten Carbonate Fuel Cell Based on Lignin Fuel Consumption (MC-LFC): Correlation Between Modeling and Experimental Results
Journal of New Materials for Electrochemical Systems
A new type of high efficiency with a low-cost solar cell having the structure of a μc-SiC/polycry... more A new type of high efficiency with a low-cost solar cell having the structure of a μc-SiC/polycrystalline silicon heterojunction
Hydrogen Cathodes in Acid Medium: Electrodeposited Nickel with H4SiW12O40
Canadian Metallurgical Quarterly, 1990
AbstractNickel was electrodeposited from baths containing different concentrations of H4SiW12O40.... more AbstractNickel was electrodeposited from baths containing different concentrations of H4SiW12O40. The influence of the SiW12O404− concentration on the electro catalytic properties of these deposits and its effects on the hydrogen evolution reaction (h.e.r.) were investigated. Improvement in the overpotential (η) and in the exchange current density (i 0), is shown to depend on the concentration of SiW12O440, while the electrocatalytic properties of the electrodeposited nickel depend on its deposition current density. It is also shown that the electrode characteristics for the h.e.r. change when Sn and Pb impurities are present in the nickel. The best electrocatalytic properties for the h.e.r. are obtained with electrodes electrodeposited with 8 g/l of SiW12O404−. Resume L'electrodeposition de nickel a partir de bains acides avec ou sans H4SiW12O404− a ete effectuee. L'influence de la concentration de SiW12O404− sur les proprietes electrocatalytiques de la reaction de degagement d'hydrogene a ces electrodes...
Improved Schottky Barrier on n-Sb\u3csub\u3e2\u3c/sub\u3eS\u3csub\u3e3\u3c/sub\u3e Films Chemically Deposited with Silicotungstic Acid
Journal of New Materials for Electrochemical Systems
The electrochemical corrosion and mechanical properties of direct current and pulsed reverse curr... more The electrochemical corrosion and mechanical properties of direct current and pulsed reverse current electrodeposited nickel and nickel-tungsten were investigated by using cyclic polarization measurement and nano-indentation techniques. Direct and pulsed reverse current electrodeposited nickel-tungsten coatings revealed a significant higher resistance to pitting corrosion when compared to direct and pulsed reverse current deposited nickel. Furthermore, pulsed reverse current electrodeposited nickel-tungsten displayed the most noble corrosion potential and higher corrosion resistance compared to direct current electrodeposited nickel-tungsten. This was attributed to the more nano- crystalline structure of the pulsed-reverse current deposited coatings when compared to that of the direct current electrodeposited nickel-tungsten. The average modulus for both direct and pulsed reverse current deposited nickel-tungsten were found to be similar but the average hardness of direct current de...
Effect of pulse reverse current waveform on tribological and mechanical properties of electrodeposited nickel–tungsten alloys on brass substrate
Tribology - Materials, Surfaces & Interfaces
Capacité d'interface et potentiel de bandes plates de CdIn2Se4 et CdCr2Se4
Resultats des mesures des capacites d'interface CdIn 2 Se 4 -electrolyte et CdCr 2 Se 4 -elec... more Resultats des mesures des capacites d'interface CdIn 2 Se 4 -electrolyte et CdCr 2 Se 4 -electrolyte. La variation de ces capacites en fonction du potentiel d'electrode est bien representee par le modele de Mott-Schottky. Les valeurs des potentiels de bandes plates obtenues pour les composes de type n sont de: -0,64 V(ecs), a pH 9,2 pour CdIn 2 Se 4 et de −1,00V(ecs) a pH 9,2 pour CdCr 2 Se 4 . On donne quelques donnees numeriques
Enhanced activity and durability of novel activated carbon-supported PdSn heat-treated cathode catalyst for polymer electrolyte fuel cells
Electrochimica Acta, 2016
Abstract Novel carbon-supported PdSn electrocatalysts for ORR in PEFCs were synthesized by NaBH 4... more Abstract Novel carbon-supported PdSn electrocatalysts for ORR in PEFCs were synthesized by NaBH 4 reduction method with and without carbon activation pre-treatment (i.e., Sn sensitization and Pd activation) followed by heat treatment at 300 °C in a H 2 /N 2 mixture and compared with Pd. The catalysts were characterized by EDX, XRD, TEM/SAED and XPS. The electrocatalytic activity for ORR was tested in acid medium using cyclic voltammetry, rotating disc electrode and chronoamperometry. For the first time, these catalysts were tested in a single H 2 /O 2 PEM fuel cell. Rotating disc electrode studies indicated that the new catalysts PdSn-3H and PdSn-2H exhibited, respectively, 10 and 4 times higher ORR activity than Pd catalyst, as well as higher methanol and ethanol tolerance. ORR proceeded through a 4-electron reduction pathway on both heat-treated catalysts. The new catalysts also exhibited improved electrochemical durability under potential cycling (600 cycles from −0.2 to 1.0 V) and constant potential (-0.55 V, 40 h). The observed high activity and durability of these catalysts may be attributed to: i) their specific alloying composition at their surface; ii) the graphitization degree of the carbon support and/or, iii) the presence of intermetallic compounds. H 2 /O 2 single fuel cell based on PdSn-2H cathode operating at 60 °C exhibited the highest ORR mass activity (1.36 A mg Pd −1 at 0.6 V) among the previous results obtained in the literature on PdSnPt, Pd-based and Pd catalysts.
241: Perinatal factors associated with moderate to severe neurological injury at two years of age following periviable delivery
American Journal of Obstetrics and Gynecology, 2016
distribution of gestational age and 64 percent to decreases in gestational age-specific mortality... more distribution of gestational age and 64 percent to decreases in gestational age-specific mortality (Table). Patterns were not explained by births and deaths missing gestational age data. CONCLUSION: Both improvement in the preterm birth rates and survival at preterm gestation resulted in the recent declines in the US infant mortality rate. Possible explanations include improvements in antenatal care such as appropriate use of progestins to prolong gestation, antenatal corticosteroids to enhance pulmonary maturation, maternal-fetal transfer to appropriate levels of care and general improvements in neonatal care.
Corrosion behaviour of steel in the presence of rare earth salts: synergistic effect
Corrosion Engineering, Science and Technology, 2015
In this work, the inhibition behaviour of rare earth (RE) salts (Y(NO3)3.6H2O, CeCl3.7H2O) in con... more In this work, the inhibition behaviour of rare earth (RE) salts (Y(NO3)3.6H2O, CeCl3.7H2O) in conjunction with metasilicates (Na2SiO3.5H2O) for carbon steel A37 and in aerated 3%NaCl solutions has been investigated. Corrosion inhibition power evaluation and surface layer characterisation have been carried out by electrochemical measurements (potentiodynamic polarisation and impedance) followed by X-ray photoelectron spectroscopy. It was demonstrated that the binary RE/ improved the protective role of oxide/hydroxide films formed on the steel. Electrochemical tests showed that the cathodic and anodic reactions were both inhibited to some extent, leading to a decreased rate of the global corrosion process. The maximum protective inhibition against corrosion attack was evident when an RE/ ion mixture was added. Surface analysis revealed the diverse nature of inhibitor coverage on the steel.
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Papers by Oumarou SAVADOGO