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. (C) 2021 Elsevier Ltd. All rights reserved.