Increase of catalyst utilization in polymer electrolyte membrane fuel cells by shape-selected Pt nanoparticles
By Dixon, D.; Melke, J.; Botros, M.; Rathore, J.; Ehrenberg, H. & Roth, C.
Published in International Journal of Hydrogen Energy
2013
Abstract
In the present work, we succeeded in supporting predominantly cuboctahedral Pt nanoparticles onto high surface area carbons while maintaining their shape. These novel catalysts were applied in a realistic fuel cell set-up for the first time and showed remarkable fuel cell performance. A 95% fraction of cuboctahedral Pt nanoparticles was synthesized using tetradecyltrimethylammonium bromide (TTAB) as a stabilizer. Transmission electron micrographs of the synthesized samples demonstrated the presence of monodispersed cuboctahedral particles of 12Â nm in size. Cyclic voltammetry (CV) studies of the unsupported cuboctahedral nanoparticles revealed the presence of Pt (110) and (100) facets. The shape-selected Pt nanoparticles were let to absorb onto Vulcan carbon by a simple dispersing procedure to obtain supported shape-selected Pt nanoparticles. Only by this gentle adsorption step of the surfactant-stabilized nanoparticles on the carbonaceous support material, the nanoparticles retained their shape. Finally an MEA was fabricated using the supported shape-selected nanoparticles and tested in a realistic H2-PEM fuel cell environment. In terms of Pt utilization, shape-selected Pt particles were found to be more effective by a factor of four in weight compared to the commercial catalyst.