Catalytic activity of dendrimer encapsulated Pt nanoparticles anchored onto carbon towards oxygen reduction reaction in polymer electrolyte fuel cells

摘要

Pt nanoparticles are encapsulated in the fourth-generation hydroxyl-terminated poly (amidoamine) (PAMAM) dendrimer (G4-OH) and anchored onto carbon to realize a novel cathode catalyst for polymer electrolyte fuel cells (PEFCs). Extensive physical and electrochemical characterizations confirm that Pt/G4-0H-C catalyst exhibits significant enhancement of catalytic activity towards oxygen reduction reaction (ORR). The mass activities (Amgpr~(-1)) at 0.9 V vs. RHE for Pt/G4-OH-CI and Pt/G4-OH-Cll, both prepared by different routes, are enhanced by 3.6 and 2.6 times, respectively, in relation to Pt/C catalyst. Dendrimer template studied here provides size-controlled preparation of Pt-based catalyst and facilitates uniform dispersion and loading of the catalyst onto carbon support. It is noteworthy that a PEFC comprising Pt/G4-0H-C catalyst with a Pt loading of ~0.1 mg cm~(-2) delivers a power density of 712 mWcm~(-2) at 0.6 V with H2 and O2 feeds. By contrast, the PEFC using Pt/C with a Pt loading of ~0.2 mg cm~(-2) delivers a power density of only 370mWcm~(-2) while operating under similar conditions.