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

Abstract 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 mgPt-1 for 60,000 cyclic voltammetry (CV) cycles and still has a high activity of 265 mA mgPt-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 mgPt cm-2 in H2-O2 fuel cell under 200 kPa absolute pressure of O2 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.