Ordered CoPt oxygen reduction catalyst with high performance and durability

Abstract

A high-performance and durable polymer electrolyte membrane fuel cell cathode catalyst composed of an ordered L1 0 –CoPt core and a thin Pt shell was designed and prepared. Under practical fuel cell membrane electrode assembly testing conditions, the cathode catalyst showed an outstanding initial mass activity of 0.6 A/mg Pt , which satisfies the U.S. Department of Energy performance target while also meeting the durability target of less than 40% loss in mass activity after 30,000 accelerated stress test voltage cycles. The high structural stability of the L1 0 –CoPt@Pt-shell catalyst was confirmed by postmortem materials characterization, and the origin of this robustness was revealed by density functional theory calculations, where the barriers for diffusion of Co atoms were observed to be significantly increased in the ordered intermetallic core. • An intermetallic ORR catalyst was prepared through a scalable impregnation method • Mass activity of 0.6 A/mg Pt and high durability were achieved in fuel cell testing • H 2 /air power density of 0.87 W/cm 2 at 0.67 V was achieved with only 0.1 mgPt/cm 2 • Order-dependent energetics of vacancy-mediated diffusion were evaluated using DFT Fuel cells with high power density and high durability could contribute to the realization of net zero carbon emissions in the transportation sector. The catalyst reported here, which uses atomic-level ordering to stabilize Co within the intermetallic CoPt lattice, achieves higher Co retention and better durability compared with conventional CoPt catalysts. The origins of this high durability were investigated using density functional theory calculations, which revealed significantly higher barriers for Co diffusion in ordered catalysts compared with disordered ones. This new intermetallic catalyst is a promising candidate for deployment in transportation and other clean-energy fuel cell applications. An oxygen reduction reaction catalyst composed of core-shell CoPt nanoparticles possessing an ordered Co–Pt core and Pt shell shows excellent performance and durability in fuel cell testing.