Platinum redispersion on metal oxides in low temperature fuel cellsElectronic supplementary information (ESI) available. See DOI: 10.1039/c2cp43248j

We have analyzed the aptitude of several metal oxide supports (TiO 2 , SnO 2 , NbO 2 , ZrO 2 , SiO 2 , Ta 2 O 5 and Nb 2 O 5 ) to redisperse platinum under electrochemical conditions pertinent to the Proton Exchange Membrane Fuel Cell (PEMFC) cathode. The redispersion on oxide supports in air has been studied in detail; however, due to different operating conditions it is not straightforward to link the chemical and the electrochemical environment. The largest differences reflect in (1) the oxidation state of the surface (the oxygen species coverage), (2) temperature and (3) the possibility of platinum dissolution at high potentials and the interference of redispersion with normal working potential of the PEMFC cathode. We have calculated the PtO x ( x = 0, 1, 2) adsorption energies on different metal oxides' surface terminations as well as inside the metal oxides' bulk, and we have concluded that NbO 2 might be a good support for platinum redispersion at PEMFC cathodes. The potential interval for platinum redispersion in low temperature Fuel Cells has been determined, as well as the ability of several metal-oxides to redisperse platinum.