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Abstract: The catalytic performance of Co/Al2O3 catalysts promoted with small amounts noble metals (Pt, Pd, Ru, Ir) for steam reforming of ethanol (SRE) has been investigated. The catalysts were characterized by the energy dispersive X-ray, X-ray diffraction, BET surface area, X-ray absorption fine structure and temperature reduction programmed techniques. The results showed that the promoting effect of noble metals included a marked decrease of the reduction temperatures of both Co3O4 and cobalt surface species interacting with the support due to the hydrogen spillover effect, leading to a significant increase of the reducibilities of the promoted catalysts. The better catalytic performance for the ethanol steam reforming at 400°C was obtained for the CoRu/Al2O3 catalyst, which presented an effluent gaseous mixture with the highest H2 selectivity and the reasonable low CO formation. [Copyright &y& Elsevier]

This work reports the results of a systematic study on the effect of Co as substituent for Ni on several physical and electrochemical properties of LaNi4.7−xSn0.3Cox metal hydride alloys, where 0≤x≤0.7. These included the unit cell lattice parameters measured using X-ray diffraction (XRD) and the electronic properties obtained using X-ray absorption spectroscopy (XAS). In general, the presence of cobalt in the alloys causes a decrease on the hydrogen equilibrium pressure and on the rate of capacity decay, and an increase in the cycle life and on the alloy activation time. A negligible effect of Co is observed in the maximum charge storage capacity and on the catalytic activity with respect to the hydrogen oxidation reaction (HOR). [Copyright &y& Elsevier]

Abstract: In this paper we report the electrosynthesis of PVA-protected PtCo films (PVA=poly(vinylalcohol)) and their activities towards the oxygen reduction reaction (ORR). PtCo electrodeposits were potentiostatically obtained in the presence and absence of PVA at distinct potentials. The film morphology and composition were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), which revealed that the use of PVA in the electrodeposition of PtCo films was decisive to achieve better film composition control. Cyclic voltammetry for PVA-protected PtCo films showed that the electrochemical surface area is dependent on the electrodeposition potentials and suggested different adsorption strengths of oxygen-containing species. Films produced in the presence of PVA presented the following activity order towards ORR as a function of the electrodeposition potential (vs. Ag/AgCl): −0.9V>−0.8V>−1.0V>−0.7V. In contrast, PtCo films electrodeposited in the absence of PVA displayed very similar activities regardless of the electrodeposition potential. The simplicity of the electrodeposition method combined with its effectiveness enabled the production of “model electrodes” for investigating the fundamental aspects of the reactions taking place in the fuel cell cathodes. [Copyright &y& Elsevier]