Highly durable cathode catalysts using polystyrene-based nanoparticles with ultralow Pt loading for proton exchange membrane fuel cell

Abstract

Developing a highly efficient and stable catalyst for oxygen reduction reactions (ORR) is one of the major challenges for the commercialization of proton exchange membrane fuel cells (PEMFCs). Herein, we developed durable ORR catalysts using an ultralow amount of platinum (~1 wt%) with three different sizes of polystyrene-based nanoparticles. All the synthesized catalysts exhibited more than 20 times higher mass activity toward ORR than commercial Pt/C catalysts in a conventional three-electrode system. In single cell tests, the catalyst with the smallest diameter of support (~100 nm) showed an initial maximum power density of 1146 mW cm-2 under H2-O2 flow even though the loading amounts of platinum at cathode were only 0.01 mgPt cm-2. Furthermore, the catalyst was extraordinarily durable, exhibiting a maximum power density of 1120 mW cm-2 after 30,000 cycles. Platinum in the catalyst was highly dispersed in the form of nanoparticles and sub-nano clusters, and these were encapsulated by thin carbon layer. The unique structures of Pt3Fe@C and sub-nano sized Pt@C were the origin of high activity and durability. The catalyst will be highly applicable in the real PEMFC market and greatly contribute to the commercialization of fuel cells by reducing the amount of platinum usage.