Multichelate-functionalized carbon nanospheres used for immobilizing Pt catalysts for fuel cells

We have developed a covalent/coordinate strategy to immobilize Pt nanocrystals (average diameter 3.5 nm) on multichelate-functionalized carbon nanospheres (CNS). The method involves the covalent grafting of triethylenetetramine onto the CNS' surface and the coordination of well-structured ethylenimine chains to Pt ions or atoms. The Pt-CNSs interface is probed with X-ray photoelectron spectroscopy to elucidate the nature of the chemical binding of ethylenimine to Pt. The Pt particle deposition can be easily controlled; to form separated and uniform Pt nanocrystals, or densely loaded Pt particles, depending on the molar ratio of Pt to amine groups. The Pt particle layer covered carbon exhibits significantly higher activity toward methanol oxidation (0.75 A mg−1 cm−2) than commercial E-TEK 40% Pt loaded carbon with the corresponding data of 0.51 A mg−1 cm−2.