Preparation and characterization of Co-W alloys as anode materials for methanol fuel cells

Co-W alloys are developed by an electroplating technique using a bath solution which contains triammonium citrate (TAC) and dimethyl sulfoxide (DMSO) under suitable plating conditions. The alloys are characterized by polarization studies in order to determine their prospects as effective anode materials for methanol fuel cells in both acidic and alkaline media. Scanning electron microscopic and X-ray diffraction analysis shows that the coatings are partially amorphous. The alloys exhibit low overvoltage even on prolonged electrolysis, and have good corrosion resistance in acidic and alkaline media. Electrochemical parameters for methanol oxidation depend on the heat treatment, deposition potential and microstructure of the deposit. © 2002 Elsevier Science B.V. All rights reserved

Electrochemical characterization of poly(ethylene oxide)- zinc chloride system and its application in rechargeable batteries

The system PEOnZnCl2 with n=4-16 was studied in view of its potential application in a solid state rechargeable zinc battery. A.c. conductivity and cationic transference number measurements, in the temperature range 20-150ºC, were performed and the electrochemical stability window was established for the polymer electrolyte with n=4 composition. The ionic conductivity, σ, of this film, follows a VTF behaviour, with an activation energy of 3.3 ± 0.2 kJ mol-1 and σ values were found between 2.50x10-7 S cm-1 at 24ºC and 4.81x10-4 S cm-1 at 145ºC. Acceptable zinc ion transference numbers of 0.36 (medium value) and decomposition voltage values between 3.19V (20ºC) and 1.44V (150ºC) were estimated. Cyclic voltammetric studies using Zn/PEO4ZnCl2/Zn cell indicated reversibility of the Zn/Zn2+ couple at the electrode/electrolyte interface. Several cells Zn(-)/PEO4ZnCl2/Nb2O5(+) were assembled and studied at 55ºC, with several discharge current densities. Results of cell’s discharge profiles, capacity values, charge-discharge cycles behaviour and stability are reported

Carbon-supported trimetallic catalysts (PdAuNi/C) for borohydride oxidation reaction

The synthesis of palladium-based trimetallic catalysts via a facile and scalable synthesis procedure was shown to yield highly promising materials for borohydride-based fuel cells, which are attractive for use in compact environments. This, thereby, provides a route to more environmentally friendly energy storage and generation systems. Carbon-supported trimetallic catalysts were herein prepared by three different routes: using a NaBH4-ethylene glycol complex (PdAuNi/CSBEG), a NaBH4-2-propanol complex (PdAuNi/CSBIPA), and a three-step route (PdAuNi/C3-step). Notably, PdAuNi/CSBIPA yielded highly dispersed trimetallic alloy particles, as determined by XRD, EDX, ICP-OES, XPS, and TEM. The activity of the catalysts for borohydride oxidation reaction was assessed by cyclic voltammetry and RDE-based procedures, with results referenced to a Pd/C catalyst. A number of exchanged electrons close to eight was obtained for PdAuNi/C3-step and PdAuNi/CSBIPA (7.4 and 7.1, respectively), while the others, PdAuNi/CSBEG and Pd/CSBIPA, presented lower values, 2.8 and 1.2, respectively. A direct borohydride-peroxide fuel cell employing PdAuNi/CSBIPA catalyst in the anode attained a power density of 47.5 mW cm−2 at room temperature, while the elevation of temperature to 75 °C led to an approximately four-fold increase in power density to 175 mW cm−2. Trimetallic catalysts prepared via this synthesis route have significant potential for future development

Conductivity studies on solid polymer electrolytes

This thematic lecture addresses electrochemical conductivity techniques for the study of solid polymer electrolytes. Types of conductivity are discussed first, followed by an outline of the features, applicability, and validity of DC and AC conductivity measurements. Techniques for the identification of the individual species responsible for conduction are then briefly reviewed.Cette étude aborde des méthodes de mesure de conductivité électrique des électrolytes polymères solides. On considère d'abord la conductivité ionique et électronique, par des mesures en courant continu et en courant alternatif. La détermination des nombres de transport pour qu'on puisse avoir des informations plus complètes sur les espèces responsables de la conduction est examinée ultérieurement

Vine Shoots and Grape Stalks as Carbon Sources for Hydrogen Evolution Reaction Electrocatalyst Supports

Activated bio-based carbons produced from vine shoots (VSAC) and grape stalks (GSAC), which have larger surface area and total pore volume than most of the commercially available activated carbons, are used as supports for palladium nanoparticles (Pd NPs). The prepared materials are characterised by elemental analysis, N2-sorption, X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, and transmission electron microscopy analysis and are then assessed as potential cathodes for the hydrogen evolution reaction (HER) in alkaline media. The electrocatalysts’ performance for HER is evaluated from cathodic polarisation curves at different temperatures and compared to that of Vulcan XC72-supported Pd NPs. Additional chronoamperometry studies helped to assess the electrocatalysts’ activity stability. The novel VSAC-supported Pd electrocatalyst exhibits good HER activity in terms of high current density at low overpotentials, leading to the best performance

Trimetallic carbon-supported catalysts for borohydride oxidation and oxygen reduction in alkaline solutions

ECEE 2019 meeting abstract