Browsing by Author "Pereira, M. F. R."
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- Catalizadores de Pt-Ru soportados sobre materiales de carbono mesoporosos para celdas de combustible de electrolito poliméricoPublication . Figueiredo, J. L.; Mahata, N.; Pereira, M. F. R.; Rangel, C. M.; Pastor, E.; Calderon, J. C.; Calvillo, L.; Lázaro, M. J.
- Influence of catalyst support characteristics and functionalization on the catalytic activity of Pt-Ru for PEM fuel cellsPublication . Calderon, J. C.; Figueiredo, J. L.; Mahata, N.; Pereira, M. F. R.; Fernandes, Vitor; Rangel, C. M.; Calvillo, L.; Lázaro, M. J.; Pastor, E.Pt-Ru electrocatalysts supported on carbon xerogels and ordered mesoporous carbons were synthesized by reduction with formate ions (SFM method). Chemical and heat treatments were applied to modified the surface chemistry of original carbon supports. Physical characterization of the catalysts was performed using X-ray dispersive energy (EDX) and X-ray diffraction (XRD) techniques, while the electrochemical activity towards methanol oxidation was studied by cyclic voltammetry (CV). Pt-Ru catalysts with nominal metal content (20 wt.%) and atomic ratios (Pt:Ru 1:1) were successfully synthesized on the different supports. Higher methanol oxidation current densities were obtained for those supports with a higher content of surface oxygen groups. Gas diffusion electrode and membrane-electrode-assembly preparation allowed an in-house built of a direct methanol fuel monocell for the evaluation of the catalysts performance. Polarization curves were measured confirming the results obtained in a three electrodes electrochemical cell by CV. Normalized power curves per weight of Pt are discussed in terms of the significant impact on noble metal loading and attained cell maximum power, in comparison with results obtained with a commercial catalyst
- Influence of catalyst support characteristics and functionalization on the catalytic activity of Pt-Ru for PEM fuel cellsPublication . Calderon, J. C.; Figueiredo, J. L.; Mahata, N.; Pereira, M. F. R.; Fernandes, Vitor; Rangel, C. M.; Calvillo, L.; Lázaro, M. J.; Pastor, E.Pt-Ru electrocatalysts supported on carbon xerogels and ordered mesoporous carbons were synthesized by reduction with formate ions (SFM method). Chemical and heat treatments were applied to modified the surface chemistry of original carbon supports. Physical characterization of the catalysts was performed using X-ray dispersive energy (EDX) and X-ray diffraction (XRD) techniques, while the electrochemical activity towards methanol oxidation was studied by cyclic voltammetry (CV). Pt-Ru catalysts with nominal metal content (20 wt.%) and atomic ratios (Pt:Ru 1:1) were successfully synthesized on the different supports. Higher methanol oxidation current densities were obtained for those supports with a higher content of surface oxygen groups. Gas diffusion electrode and membrane-electrode-assembly preparation allowed an in-house built of a direct methanol fuel monocell for the evaluation of the catalysts performance. Polarization curves were measured confirming the results obtained in a three electrodes electrochemical cell by CV. Normalized power curves per weight of Pt are discussed in terms of the significant impact on noble metal loading and attained cell maximum power, in comparison with results obtained with a commercial catalyst.
- Influence of the support characteristics and their functionalization on the catalytic activity of Pt-Ru catalysts for PEM fuel cellsPublication . Calderon, J. C.; Figueiredo, J. L.; Mahata, N.; Pereira, M. F. R.; Fernandes, Vitor; Rangel, C. M.; Pastor, E.; Calvillo, L.; Lázaro, M. J.
- Pt-Ru Catalysts supported on mesoporous carbons for polymer electrolyte membrane fuel cellsPublication . Calderon, J. C.; Figueiredo, J. L.; Mahata, N.; Pereira, M. F. R.; Fernandes, Vitor; Rangel, C. M.; Pastor, E.; Calvillo, L.; Lázaro, M. J.Pt-Ru electrocatalysts supported on xerogels and CMK-3 ordered mesoporous carbons were synthesized by reduction with formate ions (SFM method). Some of the carbon supports were chemically treated with HNO3 in order to generate oxygen groups on the surface, while other supports were heat treated. Physical characterization of the catalyst was obtained using X-ray dispersive energy (EDX) and X-ray diffraction (XRD) techniques. Results showed that Pt-Ru catalysts with similar metal content (20%) and atomic ratios (Pt:Ru 1:1) were obtained. The electrochemical activity was studied by cyclic voltammetry and chronoamperometry. Higher methanol oxidation current densities were found for catalyst deposited on chemically treated supports. Electrode preparation and MEA assembly allowed an in-house built direct methanol fuel to be fitted with the synthesized catalysts and supports in order to assess their performance. Cell and reactants were conditioned by a direct methanol test station. Polarisation curves were measured and confirmed data obtained by voltammetry, regarding the effect of heat treatment of the carbon support. Normalised power curves per weight of catalyst are discussed in terms of the significant impact on noble metal loading and attained cell maximum power, in comparison with results obtained with a commercial catalyst.