Gram-scale synthesis of active and durable oxygen reduction reaction PtFe or PtNi catalyst using commercial polystyrene

Abstract

PEMFC, that can convert hydrogen to energy in mild operating condition of 80oC, is key technology of green energy. Large amount of Pt is used in cathode due to its high overpotential. Alloying Pt with transition metal and encapsulating the alloy nanoparticle to prevent metal leaching strategies have reported high activity and durability with reduced Pt usage. However, the synthesis scale was too small or too complex. Thus, this research used commercial polystyrene and impregnated Pt through ball mill to synthesize carbon encapsulating nanoparticle electrocatalyst in gram scale. The Pt deposited on the support existed as 2~3nm cluster or larger alloy nanoparticles with high dispersion. By testing half cell activity with various contents of Fe, Ni and Pt, maximum mass activity was found to be 0.82 A/mgPt and 0.57 A/mgPt for PtFe/cPS and PtNi/cPS. After 10 000 cycles, both PtFe/cPS and PtNi/cPS retained over 70% of initial activity, confirming the enhanced durability by encapsulation. The performance was lacking at single cell, but by enhancing single cell activity through reducing the support particle size, the research would contribute to commercialization of fuel cell.