Porous, thick nitrogen-doped carbon encapsulated large PtNi core-shell nanoparticles for oxygen reduction reaction with extreme stability and activity.

We encapsulate large Pt shell/Ni core (PtNi) particles with thick and porous nitrogen-doped carbon (N–C) layers, and demonstrate that the thick N–C layers can protect the PtNi particles from dissolution and migration for an extremely long service life through both steric hindrance and chemical bond; in addition, the well mass transfer performance of the porous N–C, the thin Pt shell, and the promotion effects of N–C and Ni on Pt lead to excellent activity of the composite catalyst (N–C/PtNi). As a result, the N–C/PtNi keeps the high oxygen reduction reaction activity value of 962–1080 mA mg Pt −1 for 60,000 cyclic voltammetry (CV) cycles and still has a high activity of 265 mA mg Pt −1 even after 120,000 CV cycles. Moreover, the N–C/PtNi shows a max power density of 1.24 W cm−2 at cathodic loading of 0.1 mg Pt cm−2 in H 2 –O 2 fuel cell under 200 kPa absolute pressure of O 2 without performance decrease within 60,000 cycles. Other large noble metal-based particles are believed to gain ultrahigh stabilities and higher activities through performing the similar encapsulation. [Display omitted] 1. Porous N–C encapsulates large PtNi particle by steric hindrance and chemical bond. 2. Thick N–C layer encapsulation gives PtNi particles extreme catalytic stability. 3. Porous structure of thick N–C layer improves mass transfer and Pt activity. 4. Thin Pt shell and promotion effects of N–C and Ni on Pt lead to improved activity. 5. The max power density for H 2 –O 2 fuel cell keeps unchanged within 60k cycles. [ABSTRACT FROM AUTHOR]