Electronic properties of Pt-Ti nanoalloys and the effect on reactivity for use in PEMFCs

Theoretical investigations of Pt-Ti nanoparticles are presented using density functional theory (DFT) to study clusters up to sizes of 1.7 nm (201 atoms). Several compositions have been studied for varying sizes, and a projected density of states analysis has been performed. Changes in d-band properties have been correlated with differences in OH and CO binding energies with relation to changes in composition. It was found that a Pt-rich Pt-Ti alloy shows promise for potential use in a PEMFC with the alloy resulting in a downshift in d-center, compared to pure Pt clusters, which correlates with a weakening of the OH and CO adsorption energies. Furthermore, it was observed that varying the size of the cluster gives rise to changes in the d-band center with larger clusters typically having a more negative d-band center, although values obtained are not as negative as the d-band center for bulk Pt Ti reported in the literature.