11 documents found, page 1 of 2
New modified Nafion-bisphosphonic acid composite membranes for enhanced proton ...
Teixeira, Fatima; de Sá, A.I.; Teixeira, António P. S.; Ortiz-Martínez, V. M.; Ortiz, A.; Ortiz, Inmaculada; Rangel, C. M.ABSTRACT: Proton exchange membranes remain a crucial material and a key challenge to fuel cell science and technology. In this work, new Nafion membranes are prepared by a casting method using aryl- or azaheteroaromatic bisphosphonate compounds as dopants. The incorporation of the dopant, considered at 1 wt% loading after previous selection, produces enhanced proton conductivity properties in the new membranes,...
Enhanced proton conductivity of Nafion-azolebisphosphonate membranes for PEM fu...
Teixeira, Fatima; de Sá, A.I.; Teixeira, António P. S.; Rangel, C. M.ABSTRACT: Fuel cells are among the cleaner alternatives of sustainable energy technologies, where their proton exchange membranes continue to be a key component with many challenges and opportunities ahead. In this study, different indazole- and benzotriazolebisphosphonic acids were prepared and incorporated into new Nafion-doped membranes up to a 5 wt% loading. The new membranes were characterised, and their p...
Enhanced proton conductivity of Nafion-azolebisphosphonate membranes for PEM fu...
Teixeira, Fatima; de Sá, A.I.; Teixeira, António P. S.; Rangel, C. M.ABSTRACT: Fuel cells are among the cleaner alternatives of sustainable energy technologies, where their proton exchange membranes continue to be a key component with many challenges and opportunities ahead. In this study, different indazole- and benzotriazolebisphosphonic acids were prepared and incorporated into new Nafion-doped membranes up to a 5 wt% loading. The new membranes were characterised, and their p...
Characterization and electrochemical behaviour of nanostructured calcium samari...
Barrocas, B.; Sério, S.; Rovisco, A.; Nunes, Y.; de Sá, A.I.; Pereira, M. I. da Silva; Jorge, M. E. MeloCa1-xSmxMnO3(0 . x . 0.4) films were successfully fabricated on Indium Tin Oxide (ITO) coated quartzglass substrates by radio frequency magnetron sputtering technique (RF- magnetron sputtering) fromcompacted nanosized powder targets, and subsequent annealing at 800.C in air, for 6 h. X-ray diffrac-tion shows a pure typical perovskite phase for x . 0.1. Scanning electron microscopy and atomic forcemicroscopy rev...
Enhancing Pt electrocatalytic activity by surface functionalization of carbon s...
Capelo, Anabela; Esteves, M. Alexandra; de Sá, A.I.; Rangel, C. M.Preliminary results are presented for Pt deposited on 4-aminobenzenesulphonic acid-functionalized carbon, Pt/C_ABSA. Vulcan XC-72R was functionalized with the objective of influencing the dispersion of catalyst nanoparticles and to decrease the resistance of three phase boundaries, by introducing sulphonic groups. Electrochemical characterization of the supported catalyst was done in a 0.5 M sulphuric acid solu...
Electrochemical behaviour of ionic liquid functionalized carbon supported Pt-Ru...
Esteves, M. Alexandra; de Sá, A.I.; Rangel, C. M.Ionic liquid (IL) functionalized carbon supported nanocatalysts, including platinum-ruthenium catalysts, have been under investigation to achieve better catalytic performance on polymer electrolyte membrane fuel cells. Ionic liquids have particular physical properties, which usually improve the stabillity and dispersion of metal nanosized particles, providing an increase of the electrochemical active surface ar...
Enhancing Pt electrocatalytic activity by surface functionalization of carbon s...
Capelo, Anabela; Esteves, M. Alexandra; de Sá, A.I.; Rangel, C. M.Preliminary results are presented for Pt deposited on 4-aminobenzenesulphonic acid-functionalized carbon, Pt/C_ABSA. Vulcan XC-72R was functionalized with the objective of influencing the dispersion of catalyst nanoparticles and to decrease the resistance of three phase boundaries, by introducing sulphonic groups. Electrochemical characterization of the supported catalyst was done in a 0.5 M sulphuric acid solu...
Dielectric properties of Al-Nb amorphous mixed oxides
Di Franco, F.; Santamaria, M.; Di Quarto, F.; La Mantia, F.; de Sá, A.I.; Rangel, C. M.An impedance study of amorphous thin oxide films grown on sputtered Al-Nb alloys is presented. The characterization of the electronic properties of mixed amorphous oxide on the basis of the theory of amorphous semiconductor Schottky barrier has been carried out for anodic film on Al-92at.%Nb in a very detailed manner. The semiconductor to insulator transition of formed oxides as a function of the alloy composit...
Electronic properties of Al-Nb mixed oxide as a function of their composition
Di Quarto, F.; Santamaria, M.; Gentile, M. L.; de Sá, A.I.; Skeldon, P.; Thompson, G. E.; Rangel, C. M.
Electronic properties of Al-Nb mixed oxide as a function of their composition
Di Quarto, F.; Santamaria, M.; Gentile, M. L.; de Sá, A.I.; Skeldon, P.; Thompson, G. E.; Rangel, C. M.