Atomically Dispersed Ni-N Sites Assist Pt Ni Nanocages with Pt Skin to Synergistically Enhance Oxygen Reduction Activity and Stability.

Currently, the rarity and high cost of platinum (Pt)-based electrocatalysts seriously limit their commercial application in fuel cells cathode. Decorating Pt with atomically dispersed metal-nitrogen sites possibly offers an effective pathway to synergy tailor their catalytic activity and stability. Here active and stable oxygen reduction reaction (ORR) electrocatalysts (Pt Ni@Ni-N -C) by in situ loading Pt Ni nanocages with Pt skin on single-atom nickel-nitrogen (Ni-N ) embedded carbon supports are designed and constructed. The Pt Ni@Ni-N -C exhibits excellent mass activity (MA) of 1.92 A mg and specific activity of 2.65 mA cm , together with superior durability of 10 mV decay in half-wave potential and only 2.1% loss in MA after 30 000 cycles. Theoretical calculations demonstrate that Ni-N sites significant redistribute of electrons and make them transfer from both the adjacent carbon and Pt atoms to the Ni-N . The resultant electron accumulation region successfully anchored Pt Ni, that not only improves structural stability of the Pt Ni, but importantly makes the surface Pt more positive to weaken the adsorption of *OH to enhance ORR activity. This strategy lays the groundwork for the development of super effective and durable Pt-based ORR catalysts.