| Popis: |
This study focused on the selective deposition of Au0 onto (111), (100) faces and (111)/(100) edges of cuboctahedral Pt particles present on the Pt/C(graphite) model system. The Pt–Au/C catalysts were prepared by novel surface redox methods involving the direct reduction (DR) of AuCl 4 − species onto the Pt particles or reducing these species on the Pt–H interface, i.e., the refilling (RE) method. The presence of Au on the Pt particles was verified by means of high-resolution energy dispersive spectroscopy (EDS), and, after treatment at 300 °C in H2, the formation of crystalline Au0 aggregates was verified by X-ray wide-angle diffraction; further treatments at 500 °C in H2 led to a true Pt–Au solid solution. The Monte Carlo simulation methods indicated the selective deposition of Au0 onto the (111)/(100) edges of the Pt cuboctahedral particles when the relative Au concentration varied from 10 to 50 wt% Au. The catalytic conversion of n-heptane on the Pt–Au/C (DR and RE solids) catalysts presented an oscillatory behavior with respect to Pt/C, indicating modification of the active Pt ensembles, driven by the energy released during the exothermic n-C7 dehydrogenation and cracking reactions, which should enhance the Au0 mobility at the Pt particle surface level. |
Full text from SpringerLink