Coordination of palladium on carbon fibrils as determined by XAFS spectroscopy

To investigate the anchoring of precious metals onto carbon fibrils Pd/C-fibril samples were investigated in both the precursor and the reduced state by X-ray absorption fine structure (XAFS) spectroscopy. Analysis of the XAFS data of the freshly prepared catalyst showed a palladium-tetraamine complex in interaction with carbon. The proposed model involves [Pd(NH3)(4)](2+) coordinated to the carbon fibril surface, most probably stabilised by the carboxylic groups (through O-H bridging and charge balance) and the pi-electron system of the support. After in situ reduction, analysis pointed to small palladium particles of ca. 15 Angstrom present On the fibrils with a significant Pd-C interaction.