Highly durable fuel cell electrocatalyst with low-loading Pt-Co nanoparticles dispersed over single-atom Pt-Co-N-graphene nanofiber

The limited durability of Pt electrocatalysis toward cathodic O2 reduction reaction remains challenging, yet it is crucial for the development of proton exchange membrane fuel cells. Here, we present a rational design of a robust catalyst consisting of PtCo nanoparticles supported on Pt-Co-N-graphene nanofiber prepared through electrospun Co metal-organic framework. The catalyst delivers unprecedented mass activity of 2.48 A·mgPt−1 and retains 80% of initial value after 60,000 accelerated stress test cycles. Operando X-ray absorption spectroscopies show that the electronic configurations of Pt sites in PtCo and Co sites in Co-N4 in the hybrid catalyst are modified toward high catalytic activities. Density functional theory shows that the enhanced curvature of the substrate induced by the morphology engineering lowers the reaction thermodynamic barrier on Co-N4 sites, favoring the formation of H2O and suppressing that of H2O2. This result, along with the strong affinity of PtCo nanoparticles to the Pt-Co-N-graphene fiber, endows the catalyst with exceptional durability.