RESUMO
Proton exchange membrane fuel cell is one of the most promising zero-emission power sources for automotive or stationary applications. However, their cost and lifetime remain the two major key issues for a widespread commercialization. Consequently, much attention has been devoted to optimizing the membrane/electrode assembly that constitute the fuel cell core. The electrodes consist of carbon black supporting Pt nanoparticles and Nafion as the ionomer binder. Although the ionomer plays a crucial role as ionic conductor through the electrode, little is known about its distribution inside the electrode. Here we report the three-dimensional morphology of the Nafion thin layer surrounding the carbon particles, which is imaged using electron tomography. The analyses reveal that doubling the amount of Nafion in the electrode leads to a twofold increase in its degree of coverage of the carbon, while the thickness of the layer, around 7 nm, is unchanged.
RESUMO
Laser ablation of a bulk Pd target in DIW, acetone or ethanol was carried out for the production of nanoparticles colloidal solutions. The size distribution of the nanoparticles follows log-normal function for all three liquids, with a median diameter of 3, 1.1 and 1.5 nm and standard deviation of 0.65, 1 and 1, respectively. Amorphous carbon is found on the nanoparticles synthesized in the hydrocarbons (acetone or ethanol). In DIW pure Pd nanoparticles were generated while ablation in acetone or ethanol lead to the synthesis of palladium hydride (PdHx) nanoparticles. These nanoparticles can be used in hydrogen storage applications.
