Harnessing Controlled Dealloying–Support Coupling for Ultrastable PtNi Catalysts in PEMFC Applications

ABSTRACT Platinum–transition metal (PtM) alloys are among the most promising oxygen reduction reaction (ORR) catalysts, yet their practical deployment in proton‐exchange membrane fuel cells (PEMFCs) is hindered by transition‐metal dissolution, particle coarsening, and insufficient durability. Moreover, conventional alloying or intermetallic ordering strategies often aggravate these issues by inducing severe nanoparticle aggregation and instability. Here we report a controllable alloying–dealloying strategy to construct PtNi nanoparticles confined in an N‐doped carbon framework (Pt 1 Ni 1‐x @Ni x _NC). Ammonia‐assisted dealloying produces a Pt‐rich shell with an alloyed core, while the N‐doped carbon anchors the released Ni atoms form Ni–N/C moieties, thereby suppressing agglomeration and strengthening metal–support interactions. This coordination–support coupling optimizes Pt 5d orbital occupation, weakens oxygen adsorption, and accelerates ORR kinetics. Consequently, Pt 1 Ni 1‐x @Ni x _NC exhibits a half‐wave potential of 0.932 V and an ultrahigh mass activity of 2.028 A mgPt −1 , which is 8.75‐fold higher than commercial Pt/C and among the best values reported to date for PtNi‐based catalysts. Remarkably, it shows only a 6 mV half‐wave potential loss after 30,000 cycles, demonstrating exceptional durability. In PEMFCs, the fuel cell delivers 975 mW cm −2 peak power density and retains 91.9% of initial performance, underscoring a generalizable approach for designing durable, high‐performance low‐PGM catalysts for next generation PEMFCs.