Ana Lilia Ocampo

Influence of the hydrophobic material content in the gas diffusion electrodes on the performance of a PEM fuel cell

In the present study the influence of the hydrophobic material (Teflon, polytetrafluoroethylene) content in the gas diffusion electrodes (anode and cathode) on the performance of a H 2 /O 2 proton exchange membrane fuel cell is reported. The potential-current (E-I) evaluation of the fuel cell indicated that a combination of 10 and 30 wt% of Teflon, respectively, in the cathode and anode gave the best results.

Electrochemical characterization of tungsten carbonyl compound for oxygen reduction reaction

Abstract The results of electrochemical studies carried out on Wx(CO)n electrocatalyst are presented in this article. Wx(CO)n was synthesized from W(CO)6 in xylene at 140°C. The kinetic studies were carried out in 0.5 M H2SO4 solution under a three-electrode configuration. Linear voltametry studies on Wx(CO)n reveal significant catalytic activity of the material for oxygen reduction. Koutecky–Levich analysis of the voltametry data shows that the reaction follows first-order kinetics and the value of the Koutecky–Levich slope indicates a multi-electron charge transfer in the oxygen reduction reaction. The value of Tafel slope is found to be −120 mV / decade from the mass-transfer-corrected Tafel plots. The charge transfer coefficient and exchange current density were found to be 0.66 and 8.4×10 −5 A/cm 2 , respectively.

Synthesis and characterization of osmium carbonyl cluster compounds with molecular oxygen electroreduction capacity

Abstract A transition metal cluster electrocatalyst based on Osx(CO)n was synthesized by pyrolysis of Os3(CO)12 in 1,2-Dichlorobenzene (b.p.≈180°C) under inert atmosphere (N2). The electrocatalytic parameters of the oxygen reduction reaction (ORR) for an Osx(CO)n catalyst were studied with a rotating disk electrode in 0.5 M H 2 SO 4 electrolyte. The diffusion coefficient and solubility of O2 in 0.5 M H 2 SO 4 were calculated. Koutecky–Levich analysis of the linear voltamperometry data showed that the reaction follows first-order kinetics and the value of the Koutecky–Levich slope indicates a multielectron charge transfer during the ORR. The value of the Tafel slope obtained from the mass transfer corrected Tafel plots is 131 mV / decade . The performance of the catalyst in a H2/O2 PEM fuel cell cathode was evaluated and found to be nearly as good as that of Pt.

Simultaneous Au(III) extraction and in-situ formation of polymeric membrane-supported gold nanoparticles: a sustainable process with application in catalysis

A polymeric membrane-supported catalyst with immobilized gold nanoparticles (AuNPs) was prepared through the extraction and in situ reduction of AuIII salts in a one-step strategy. Polymeric inclusion membranes (PIMs) and polymeric nanoporous membranes (PNMs) were tested as different membrane-support systems. Transport experiments indicated that PIMs composed of cellulose triacetate, 2-nitrophenyloctyl ether, and an aliphatic tertiary amine (Adogen 364 or Alamine 336) were the most efficient supports for AuIII extraction. The simultaneous extraction and reduction processes were proven to be the result of a synergic phenomenon in which all the membrane components were involved. Scanning electron microscopy characterization of cross-sectional samples suggested a distribution of AuNPs throughout the membrane. Transmission electron microscopy characterization of the AuNPs indicated average particle sizes of 36.7 and 2.9 nm for the PIMs and PNMs, respectively. AuNPs supported on PIMs allowed for >95.4 % reduction of a 0.05 mmol L-1 4-nitrophenol aqueous solution with 10 mmol L-1 NaBH4 solution within 25 min.

Sintered MoxSy(CO)n and Mox(CO)n: application in oxygen reduction reaction, hydrogen evolution and supercapacitors

Abstract Mox(CO)n and MoxSy(CO)n ectrocatalysts were synthesized following a sintering process in air at 150°C. The catalysts were characterized using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and cyclic as well as linear voltametry measurements. The results indicated that sintered Mox(CO)n possesses catalytic activity for oxygen reduction reaction. Incorporation of sulfur to the carbonyl compound seems to nullify the catalytic activity of the material. These materials are porous in nature and formed in amorphous form or with poor crystallinity. The voltammograms indicated its possible application in supercapacitor electrodes and for hydrogen evolution reaction.

Synthesis and characterization of hybrid membranes based on sulfonated poly(ether ether ketone) (SPEEK) and polysiloxane

AbstractPolymer electrolyte membrane fuel cells (PEMFC) for hydrogen and methanol have attracted the attention of research groups for many years mainly because they are promising candidates for clean and renewable power sources. The most common commercial product used as PEM is Nafion®. However, certain limitations and high production costs stimulate the research of new materials. In this work, new hybrid proton-conducting membranes for PEMFC based on sulfonated poly(ether ether ketone) and an inorganic–organic polysiloxane phase were obtained with the objective of improving its mechanical, thermal, and chemical resistance properties. The hybrid membranes were prepared by dissolving the base polymer in DMSO and adding different amounts of the polysiloxane phase previously obtained from polydimethylsiloxane and a cross-linking agent (tetraethyl orthosilicate or phenyltrimetoxysilane). Membranes were characterized using infrared spectroscopy and thermal analysis. Macroscopic properties as water uptake, ion-...